The pediatric airway : More questions than answers

This one is for all of you who love the pediatric airway & related syndromes.



These are visuals of a child we anesthetized for ocular surgery.

Take a closer look at the pictures and see if you can figure out what syndrome this is.

I'll throw in a hint: Take a good look at those ears!

Pulmonary Hypertension in Children

Pulmonary Hypertension (PHT) is more common in children than in adults. It is defined as an elevation in the pulmonary artery to at least half of the systemic pressure. PHT occurs as a result of many disease processes of childhood, including sickle cell, cystic fibrosis, bronchopulmonary dysplasia, chronic pneumonia as well as several congenital heart lesions which produce left to right shunts.
Children with PHT are at risk for acute decompensation during the perioperative period. The morbidity rate for these kids is eight times that of normal children. They respond to episodes of hypoxemia with prolonged and exaggerated hypoxia, sometimes only responding to long periods of hyperventilation, and pulmonary vasodilators.

For children with the most severe disease - those with pulmonary artery pressures that are equivalent to or higher than systemic pressure. Extreme caution should be used during the perioperative period and practitioners that are familiar with this disorder and the treatment of complications including cardiac arrest should manage them.

Rae Brown, M.D.

Managing Infants and Children With Congenital Heart Disease

Managing Infants and Children with Congenital Heart Disease

In order to successfully manage an infant with congenital heart disease,
whether for cardiac or noncardiac surgery, there are essential questions
that the clinician must answer.

1. What are the flow characteristics of blood in the infant’s heart?
Where does the deoxygenated blood come from and where does
it go?
Example: In patients with Truncus Arteriosus, blood returns from the
body to the right atrium and then leaves the heart through a large
common vessel that feeds the pulmonary and the systemic
circulation.

2. Which ventricle is the most affected? Which ventricle supplies blood
flow to the pulmonary circulation? Which to the systemic
circulation?
Example: Patients with hypoplastic left heart do not have an
effective left ventricle. In these cases, the right ventricle pumps
blood to the systemic and the pulmonary circulation.

3. Is the pulmonary blood flow normal? Is the pulmonary resistance
elevated?
Example: Infants with a large VSD will have significant increases in
pulmonary blood flow producing a clinical picture of pulmonary
congestion.

4. Are there abnormal communications between the pulmonary
circulation and the systemic circulation?
Example: Infants with ASDs have an abnormal communication
between the right and the left side of the heart. The predominant
flow of blood is usually left to right unless pulmonary vascular
resistance is significantly elevated.

5. Are the valves normal? Are they competent as valves? Do they
obstruct the flow of blood?
Example: Congenital aortic stenosis obstructs the flow of blood out
of the left heart.

6. Is there a normal rhythm?
Example: Infants with WPW can develop supraventricular
tachycardia producing failure if it is allowed to continue.

Further characterization of congenital heart disease can be
accomplished by clinically placing the lesion in one of four categories:
1. Cyanotic with normal blood flow,  2. Cyanotic with decreased
pulmonary blood flow, 3. Acyanotic with increased pulmonary blood
flow, and,  4. Acyanotic with obstructed pulmonary blood flow.

Examples of these categories:

Cyanotic with normal pulmonary blood flow: Single ventricle lesion and
double outlet right ventricle after a Fontan procedure; Transposition of
the great vessels (TGA) after a atrial septectomy

Cyanotic with decreased pulmonary blood flow: Tetralogy of Fallot
after a BT shunt; TGA after BTS

Acyanotic with increased pulmonary blood flow: ASD, VSD, PDA,
Aorto-Pulmonary Window

Acyanotic with obstructed pulmonary blood flow: Pulmonic stenosis,
Aortic stenosis, Hypoplastic left heart syndrome, Coarctation of the
aorta.

Infants with congenital heart disease suffer from abnormal anatomic
variations as well as the usual issues that characterize the transition from
fetal to neonatal life. Their metabolism demands a high heart rate, the left
ventricle has immature muscle elements and there are anatomic
communications that, while physiologically established, are not
anatomically complete – PFO, PDA.
With this as background, the management of infants with congenital
disease, repaired or not must give consideration to the conditions that are
present during the operative procedure; conditions that relate to the
anesthetics that are being given as well as the conditions that are
created by the surgeon and the surgical procedure.
A reasonable example of how complex the management becomes
relates to the patient who was born with a double outlet right ventricle
and has been repaired with a Fontan procedure.  This surgical procedure,
the Fontan, was developed in the early 1970’s and has been modified
many times since the original description. It is used for many patients with
single ventricle physiology, including hypoplastic left heart syndrome. In
this procedure venous blood is returned to the pulmonary circulation
through a conduit that has no pumping function. Usually, the SVC and the
 IVC are connected to the right pulmonary artery, the IVC through a baffle
created through the right atrial wall. A small defect is left in the baffle to
decompress the right heart and this produces some systemic
desaturation.
Patients that have had a Fontan are dependent on the central venous
pressure for filling of the pulmonary circulation and are every sensitive to
elevations in pulmonary vascular resistance. Increased intraabdominal
pressure, produced by laparoscopy, can reduce venous return as can
increased ventilating pressures.  Hypoxemia and hypercarbia can elevate
pulmonary vascular resistance. Either of these will reduce blood flow to
the right side of the heart and subsequently cardiac output. As an aside,
cannulation of the right internal jugular vein is contraindicated because of
the risk of thrombosis.
Thus, evaluation of the anatomical conditions as well as the physiological
conditions that have been created by palliative procedures must be
considered in managing these infants. Communication with the patient’s
cardiologist prior to taking a child to the operating room aids
immeasurably in defining the clinical conditions that the anesthesia care
provider will be presented with. By understanding the anatomy and the
physiology, the astute clinician can plan for common eventualities and
avoid most disasters.
Rae Brown, M.D.

What Do We Learn From Children?

Children teach me important lessons almost every day.

Unconditional love - I rarely see children that don't love their parents. They cling to them because they are familiar and trusted.

Curiosity - Three year olds are invariably curious about the hospital environment. They are always happy to listen to their heart beating and to investigate any of the medical utensils that you have in your pocket. Lately, I have found that the iPhone is an excellent toy for children.

Resilience - I have seen infants and children with some of the most horrific injuries survive and flourish. It is  testament to our species' ability to  survive that the brain and body of these young ones can regenerate after significant injury.

Honesty - Little kids will tell you the truth about things that others may not want you to know. It is refreshing when your patient can come clean about the house habits. Of note is that they routinely lose this ability at about age eleven - for many it does not return.

Children teach us many lessons in our day to day interactions with them. Their innate ability to force us to consider what we are doing and how we present ourselves is remarkable. Thankfully innocence has a way of allowing adults an out when we recognize that we have let them down in some way or have failed them. I enjoy interacting with kids every day in part because I can learn so much about life from them.

Rae Brown, M.D.

The Medical Management of Infants and Children

Children are usually healthy when they come to the operating room for a surgical procedure. As a tertiary care center, however, we see a disproportionate number of children with chronic disease. These superimposed processes will affect the conduct of the surgical procedure and the anesthetic management of the child including the way that the child views you as a provider, the amount of stress that the parents feel, and sometimes even the developmental level of the child. An understanding of the natural history of some of the common diseases that affect infants and children is important for the practitioner that sees children as a part of their practice.

             As a general rule, if a child is not growing they are ill. Growth along a standard curve will determine whether caloric expenditure is being met by intake. Chronic, untreated illness increases work and thus caloric expenditure.  As examples, if a child has congenital heart disease, diabetes or asthma and if the child is not following some growth curve, then the therapy is not completely effective. (EG. For children with congenital heart disease, a lack of growth usually relates to cardiac failure or profound hypoxemia) Thus, an early signal to the practitioner that a child is ill is the lack of linear growth.

I would like for you to consider a few of the most common childhood diseases that we encounter. I will briefly discuss the natural history of these processes and the part that the disease plays in the perioperative management of an individual patient.

The child with congenital heart disease

Consider a child with Tetralogy of Fallot. These children present with an over riding aorta, VSD, RVH and infundibular hyperplasia. Because of these anatomic abnormalities any increase in pulmonary vascular resistance may lead to decreased pulmonary blood flow and increased cyanosis. For these children, control of the flow of blood back and forth through the VSD is an important determinant of general health. In these children any hypoxemia will produce an increase in pulmonary vascular resistance. Concomitant increased autonomic tone can lead to infundibular spasm, further reducing pulmonary blood flow – a so-called “tet spell”. Tet spells represent episodes of profound hypoxemia and can be treated by increasing the systemic vascular resistance so that blood is preferentially shunted left to right through the VSD increasing blood flow to the lungs. Neosynephrine is the drug of choice to increase systemic vascular resistance.

Growth of infants with TOF reflects the balance of hypoxemia and myocardial failure. Pulmonary blood flow that is luxuriant will increase lung water and the work of breathing. Unusual restriction of pulmonary flow will produce profound hypoxemia.

Current practice is to band the pulmonary artery soon after birth to restrict blood flow from the VSD and diminish the risk of failure. An infant that comes to the operating room before a definitive repair can be evaluated by determining the resting respiratory rate and whether the child is meeting growth goals.

The child that has had a Fontan procedure for palliation of hypoplastic left heart or other congenital cardiac anomalies represents a special case for the pediatric anesthesia practitioner. These children are dependent on the passive filling of the right heart in order to maintain cardiac output. Reduction of the filling pressure whether by dehydration or by an increase in pressure in the abdomen, such as during laparoscopy, will reduce the cardiac output dramatically. Most of these infants utilize the right ventricle for systemic and pulmonary blood flow.

The child that has pulmonary artery hypertension also represents a significant management problem for the anesthesiologist. PAH is common in children with untreated congenital heart disease in which the flow of blood left to right across an intracardiac defect is allowed to proceed unabated over time. Progressive remodeling of pulmonary artery vasculature with increases in the number and size of arteriolar smooth muscle results in increases in the pressure required to push blood through the pulmonary circuit. In these children, hypotension during induction or during the surgical procedure can

Apnea of Prematurity

            Apnea, defined as cessation of respiratory airflow, is common in premature infants prior to 36 weeks post conceptual age.  For a variety of reasons, infants that undergo surgery and anesthesia are at increased risk. Apnea associated with desaturation and/or bradycardia may be life threatening to these infants.

            Risk factors for apnea include hypothermia, use of narcotics, airway obstruction and hypoxemia. Anemia, GE reflux and hypoglycemia have also been associated with an increased incidence. Chronically ill infants may be chronically treated with theophylline or caffeine to prevent apnea

            The anesthetic for a premature infant should, ideally, be designed around their immature respiratory center and the probability of postoperative apnea. Short acting inhalational anesthetic agents, regional anesthesia rather than narcotics and increased attention to maintenance of normothermia, normoglycemia and a normal hematocrit reduce the probability of apnea. Treatment of at risk infants with methyl-xanthines such as caffeine or theophylline is extremely effective in reducing the incidence of apnea. Caffeine is available as a sodium benzoate derivative. Administration of 20 mg/kg as a slow bolus will provide several days of protection against apnea. 

The infant that has a history of severe apnea and has undergone a substantial operative procedure requiring blood replacement should probably remain ventilated postoperatively until homeostasis is attained. Likewise, neonates less than 2500 grams that are cold or metabolically unstable should remain intubated after the surgical procedure.

Infants less than 52 weeks post conceptual age should be monitored after general anesthesia for at least 12 hours.

             

Asthma

 Fifteen percent of children in the US will wheeze at some point during their development. Children from families that smoke and children that have been infected with the respiratory syncitial virus as infants are at increased risk. Usually mild and treatable with beta-adrenergic inhalers asthma may be significant, especially if the family fails to reduce the load of bronchial irritants in the home. Children from homes in which cigarettes or other tobacco products are used are at an especially high risk. Inhaled steroids and combination therapy – inhaled bronchodilators and steroids -  for children with chronic rather than episodic disease is considered a standard. Systemic steroids are contraindicated unless bronchospasm is very severe because of the impact on bone growth.

The child with significant asthma represents a problem for the anesthesiologist because of the irritability of their airways and the dramatic bronchospastic response to foreign body placement or the use of irritating gases such as desflurane. Sevoflurane has profound bronchodilatory properties and is the mainstay for maintenance of anesthesia. For children that are unresponsive to more conservative measures aminophylline is still available as is epinephrine.

Obstructive sleep apnea

OSA presents in obese children and may be ameliorated by airway surgery, including tonsillectomy. Many of these children are hypoxemic at night and the worst will have elevated pulmonary artery pressures leading to right heart failure. These children are very sensitive to narcotics after surgical procedures. It is important to note that, given the widespread obesity that is now seen in the pediatric population, the number of children that have OSA greatly exceeds the number that have been diagnosed. Children with a BMI over 35 are at high risk. If the same child has hypertension it really clinches the diagnosis.

Obstructive sleep apnea is a problem because of the sensitivity of these patients to narcotics and other sedatives. A common, and sometimes lethal, combination of a fentanyl patch for postoperative pain control and promethazine to control nausea will produce excessive somnolence. For this reason, the ambulatory treatment of these patients must be reserved for patients with home support that is impeccable.

Retrolental Fibroplasia

 RLF continues to be a common clinical entity despite our knowledge of the pathophysiology, because of the large number of very premature infants that are resuscitated. It is a response of the native vasculature of the retina to extreme changes in arterial oxygen levels. Hypoxia followed by relative hyperoxia produces neovascularization of the retina and may produce subsequent blindness. Untreated neovascularization will produce retinal detachment if untreated. This entity can be treated with cold probe and laser. The utilization of high levels of oxygen during anesthetics and surgical procedures in the premature is contraindicated if it can be avoided.

Bronchopulmonary Dysplasia

The resuscitation of infants less than 25 weeks of gestation, despite the use of prenatal steroid compounds to mature the lungs of the fetus and exogenous surfactant for postnatal use, has produced a whole new generation of infants with chronic lung disease. Because the final development of alveoli off of terminal bronchioles doesn’t begin until after thirty weeks, the effect of chronic ventilation and high levels of inhaled oxygen used in the treatment of respiratory distress syndrome is a serious inflammatory response, which resolves with fibrosis – Bronchopulmonary Dysplasia (BPD).

Many of these infants have well-established pulmonary hypertension that is exacerbated by events that surround a surgical procedure. Pain, hypoxemia, cold stress, or acidosis will aggravate the already increased pulmonary artery pressures and escalate V/Q mismatch producing profound hypoxemia. Because the right heart is under continuous stress, situations such as this with low levels of arterial oxygen and high PA pressures, produce right heart failure, which is, of course, the most common cause of left heart failure.

Infants with BPD vary in the amount of support that they require after the acute insult. Some go home on nasal cannula oxygen and diuretics. Many will leave the hospital accommodated to arterial carbon dioxide levels significantly above the norm; some greater than 60. For these infants, the balance of intravascular volume sufficient to support the cardiac output and grow but not so much that pulmonary interstitial water is increased is critical. For some the balance is so tenuous that postoperative ventilation is the only appropriate method of management for any surgical procedure more extensive that PE tubes.

Seizure disorders

 Children that have chronic seizure disorders are routinely placed on anticonvulsants and most are monitored for the therapeutic level of the drug. Efficacy of the regimen can be assessed by asking about the most recent level and the last time that the child had a seizure. For children that have seizures, which are particularly difficult to control, some provision for assuring the administration of the drug during the NPO period must be made.

 Most of the anticonvulsants have an impact on the metabolism of anesthetic drugs. Many will accelerate metabolism via cytochrome P450 reducing the beta half-life of action. Muscle relaxants are especially prone to this activity.

Valproic acid is commonly used for control of complex partial seizures. Massive bleeding associated with the inhibition of platelet function has been reported.

Sickle Cell Anemia

            Sickle cell anemia is still common in the United States. Predominately present in African Americans, it is also seen in Asians, Hispanics and people from the Indian subcontinent. It is the most common inherited genetic disorder in African Americans and the prevalence is about 1 in 400 live births in that population. An understanding of the pathophysiology over the last twenty years has reduced the number of children that present with severe sequelae such as stroke, pulmonary infarction and septic shock. The use of hydroxurea to produce myelosuppression and increase the production of Hgb F has been effective in cutting the number of painful crises in most children by one-half. 

            Red blood cells sickle in affected children when they are subjected to acidosis, hypoxia, or cold stress. Even the placement of a tourniquet for the surgical procedure can put the child at risk. Red blood cells that have an abnormal configuration do not carry oxygen efficiently and will be rapidly eliminated from the circulation by the microvasculature, or the spleen. Most children that are homozygous for S hemoglobin will have infarcted their spleen by the time that they are four years old. After this they are at increased risk for bacteremia and septic shock. Currently children that have good pediatric care receive pneumococcal vaccine early in their lives. Many of these children are also on prophylactic antibiotics.

            Children with sickle cell disease may present with a history of stroke or multiple episodes of lung infarction. These children may be on a hypertransfusion protocol in order to reduce their risk of a crisis. Those children that have not had any of these events and have been followed closely by knowledgeable clinicians have been shown to tolerate surgical procedures that are of short or intermediate duration, without tourniquets, with simple transfusion to a hematocrit of ten. For complicated patients, in addition to making every effort to avoid a sickle crisis, the level of Hgb S should be reduced to a level below 20% by exchange transfusion.

Sickle cell disease and the other hemoglobinopathies that afflict children and adolescents produce acute and chronic pain and represent a management dilemma for pediatricians and hematologists. Issues related to narcotic addiction, pseudo-addiction and tolerance are often encountered. Acute, severe pain, the presence of chronic disease, inevitable disagreements about the need for narcotics between patient and practitioners, and the lack of available resources for psychological and social support interact to reduce the possibility of successful long-term management.

Painful crises in patients with SS disease begin early in life, sometimes in infancy. The inability of a preverbal infant or child to communicate pain should not be taken as evidence that pain is not present. On the other hand, the natural history of painful crisis in children with sickle cell is variable. A substantial number of patients will have few hospitalizations for painful crisis while a few will require intensive medical therapy to prevent painful crisis and remain functional.

Frequently, patients with sickle cell refer themselves to an emergency room for treatment of a painful crisis. Because these healthcare providers do not know them, they may question the need for aggressive treatment. The anxiety that surrounds the possibility of lack of treatment accelerates the desire to be treated. In adolescents, faced with the possibility of not being treated at some point in the future, drug-seeking behavior – pseudo addiction  - becomes a part of their life. In part because of this circumstance, ER treatment of painful crisis should be discouraged or an accepted method for tracking the patient (database demonstrating history of past hospitalizations) should be established. Many states now track narcotic compounds that are prescribed. This too will assist as it provides some reassurance to the health care provider.  A comprehensive program to provide psychological and social support for these patients and their families will provide them a measure of  confidence that they are being heard.

Commonly, when care is not coordinated, or when the patient doesn’t avail themselves of comprehensive services, no health care provider can feel that they understand the patterns of illness for a given patient. When this happens, and the patient presents with painful crisis, physicians may believe that the patient falls within a group of chronic drug seeking individuals that may divert narcotics. Subsequently, the desire for narcotics increases and the cycle of pseudo addiction begins.

If the patterns of pain are known and if there is ongoing support, there is the opportunity to reduce drug-seeking behavior and decrease or shorten hospitalizations for painful crises. This should be one goal of a comprehensive program and, to some extent, the ongoing treatment of the patient may need to be contingent on close follow up and involvement with all of the resources that are available for support.

Cystic Fibrosis

            CF is the most common heritable disease in the Caucasian population with an incidence of 1: 3500 live births. It is an autosomal recessive trait that produces abnormalities in the CFTR gene. Though there are many permutations of this abnormality, in patients with the classic form of the disease, the abnormality affects the protein that acts as a chloride channel at mucosal surfaces.  Under normal conditions, as chloride exits a mucosal cell, water follows and mucous is thinned. In the patient with CF, mucous is thick and reduces mucociliary transport – a primary method for carrying debris out of the lungs. In addition, though it is thought of as primarily a pulmonary disease, evidence of the disorder can be found in the gut, liver, the exocrine pancreas and the skin. For the anesthesiologist, however, it is the pulmonary complications that are most problematic. Current therapy for pulmonary CF includes bronchodilators, inhaled antibiotics and adjuvants used to break up the tenacious secretions that inhabit the airway. Of note, many adolescents with CF are substantially underweight and this affects their ability to mount a substantial stress response.

Patients with cystic fibrosis may have pulmonary hypertension and heart failure, diabetes, anemia, GE reflux, malabsorption as well as abnormalities of the sweat glands. It is important to determine the severity of these secondary processes, as they will play a large role in morbidity and mortality associated with a surgical procedure.  

 All an eagle would really like, is a teapot

The Safety of Our Children

I am often amazed at the lack of insight that people have about the safety of their children. I understand that it is difficult to police them all of the time and I know that I see a disproportionate number of injuries as I take care of the children in the operating room. Still, some of the injuries occur with a frequency that suggests a fundamental lack of knowledge about the possibilities for substantial damage in activities that adults encourage or turn a blind eye to. Let me give you some examples of some of the injuries that we see regularly:

1. Running with sticks - There seems to be a magnetic attraction between children and sticks. Running with sharp objects appears to be a right of childhood. After seeing many eye injuries over the last twenty five years, I think that this activity should cease. Being blind in one eye is a terrible price to pay for the lack of adult supervision.

2. ATVs - I have spoken about this before. Still a bad idea.

3. Trampolines - The American Academy of Pediatrics agrees with me on this. Trampolines are dangerous, even with a spotter. Broken limbs and broken necks happen too often when parents don't recognize the potential harm.

4. Guns - Let's be clear: Guns harm more than they protect. Children find them and play with them. Innocent people get shot, kids inadvertently harm themselves or their friends, suicides are easier to accomplish. If you have a gun in your home, plan on a bad outcome related to it...it is a matter of time.

5. Lack of supervision - I have seen many mangled children in my professional life. Most of these injuries were accompanied by the lack of adult supervision - dog maulings, drownings, burns. Needless injury that changed the life of a child forever because someone didn't think that anything could happen.

We owe it to our children to recognize the dangers in life and to make a reasonable effort to avert injury.

Rae Brown, MD

The Children That We Are Seeing Now

Every day we are seeing children that are massively overweight. Everyday we encounter kids with the diseases of late middle age - diabetes, hypertension, hyperlipidemia. Everyday we see sleep disordered breathing, and the attendant problems with behavior and learning.

I may be wrong, but I see a public health crisis growing in front of us that is bigger than cancer and AIDS; a generation of super overweight adults that will have the chronic diseases that accompany obesity and will have had them since childhood. In terms of healthcare finance, this is the bomb that will wreck our treasury. In terms of worker productivity, this is the glue that will cause the economic machine to grind to a halt. In terms of our ability to be identified as a world leader, this is a major factor that can spell our demise.

Of course, there is a fix to this, but I don't think that anyone is interested in hearing it yet. The folks in Northern Europe have it right, though. They ride their bicycles everywhere. Don't see many of the super overweight there. We must become a country addicted to movement, just as we have become addicted to fast food. If we do not, I predict a rough road ahead through the first half of the 21st century.

I really feel sorry for the kids that I take care of that have massive weight problems at a young age. I know the life that they face and the disability that will prevent them from living it fully. We often speak about the amazing things that the future holds for us but if we don't fix this problem, for many, there will be naught but a dark future.

Rae Brown, M.D.

Recognizing a Sick Baby

Infants are funny. When they are awake, they are usually upset about something - hunger, a wet diaper - something. When they are asleep, they are peaceful. Healthy babies have lots of muscle tone, look toward voices, and respond when touched. Infants that are healthy have warm extremities and are pink. If you press on a toe the red color, capillary refill, returns almost immediately. In a word, healthy babies look and act healthy.

Sick babies are different. They have an abnormal breathing pattern with respiratory pauses. Tone is diminished and they may have a prolonged capillary refill. Sometimes infants that are septic will grunt when they breathe, creating auto peep. They may guard their abdomen if touched and their color may be grey rather than pink and rosy.

Some mistakenly think that a baby that is not fussing about something is a "good" baby. Many times these infants are tightly swaddled and the lack of racket is perceived as a positive thing. Sometimes these babies are very sick, as opposed to very good and you can't make that diagnosis if you don't look at the baby.

So, if there is any question in your mind about a baby, pull the blankets off and look at the breathing pattern, the tone, and the skin color. Feel the extremities, press on a toe. Pick the baby up and look at them. Sick babies look sick. They will tell you if there is a problem...but you have to look.

Rae Brown, MD

Postoperative Management of Infants after Major Abdominal Surgery

Infants with intra-abdominal pathology often come to the operating room for repair or resection. Some of these infants have concurrent acute lung disease, often related to lack of surfactant production. This surfactant deficiency is associated with prematurity but is exacerbated by the  metabolic acidosis caused by the primary surgical disease process. Because of the lung disease, clinicians that are caring for the infant in the postoperative period may be hesitant to continue the fluid resuscitation that begins in the operating room. Many times, the lack of continued volume expansion is associated with the development of severe acidosis and hemodynamic instability. The response to this is often the use of vasoconstricting agents to increase the blood pressure and , in fact, this makes the clinical situation worse. In almost all of these cases the infant will fare better with judicious volume expansion than with fluid restriction, as this treats the primary problem, loss of intravascular volume into the bowel wall. Intravascular monitoring and determination of continued urinary output is usually required to determine whether appropriate volumes are being given.

The volume of fluid that is given to these infants is important. The quality of the fluid that is administered is equally important and consideration must be given to the defects in renal function that are present in the newborn. Infants have difficulty clearing free water, sodium and chloride. Saline, with an excess of sodium and chloride relative to the infant's serum levels will rapidly produce high levels of sodium and chloride, sometimes resulting in a secondary acidosis. This secondary acidosis - hyperchloremic metabolic acidosis - is a common cause of refractory disturbances in patients that are being resuscitated.

So, for infants that have had intra-abdominal catastrophes, the volume resuscitation must continue through transport and into the postoperative period. The use of saline as the sole IV solution for this resuscitation will produce a secondary acidosis and exacerbate the primary disease process. Solutions such as ringers lactate are more hypotonic and can be applied to the situation without the development of secondary metabolic disturbances.  

Preoperative Behavioral Stress in Children

Up to 60% of children between the ages of 1 and 10 that undergo outpatient surgery exhibit behavioral changes in the ensuing two weeks. These behaviors, like bed wetting, night terrors, and insomnia can, in large measure be predicted and to some extent ameliorated by the actions of clinicians during the preoperative period.

Important to the process is recognizing children at risk. Some of the characteristics that are associated with increased preoperative stress include:

1. Age - Children between the ages of  1 and 4 are especially frightened about the prospect of leaving their parents.
2. Prior surgical history - Children that have chronic diseases an/or have had multiple surgical procedures often have more anxiety than those for which the whole experience is new.
3. Temperament - Some children are timid, frighten easily and require more parental support for their age than other children. There is  nothing wrong with having a temperament that is different. It is just an observation. We are all different, thankfully.
4. Anxious Parents - Children sense their parents anxieties

Once a  clinician has identified a child at high risk for stress prior to the surgical procedure, and one senses these things while talking to the child - remember - always talk to the child - then make a decision about the pharmacological support that the child will need during the preoperative period and explain to the parents your assessment of the child's level of discomfort and what your approach will be. I try to explain every step in the process if I can . I find that parents appreciate candor and a gentle approach. It speaks to the comfort level that a clinician has and that, in turn reduces their level of anxiety.

Rae

Pain: What is it?

Pain is a private event that occurs within the nervous system, usually in response to injury. The perception of pain, which occurs at the cortical level of the brain is unpleasant, usually eliciting a withdrawal response. There is a profound emotional component to pain that is both an immediate response to injury and an amplifier of the response. From an evolutionary perspective, pain protects from danger and identifies injuries that we may not be able to see. There are peripheral receptors that fire in response to injury sending signals to long neurons in the spinal cord. These neurons end in the thalamus. From there secondary neurons radiate to the cortex, bringing the signal of injury to our consciousness.

This multi level anatomical mechanism is important in the treatment of pain because the signal that is generated in the periphery can be suppressed or down regulated along its path. 

As an example, if you talk to a child, or distract them in some way before a painful procedure, the emotional  response to the perceived injury will be attenuated and the intensity of the pain can be suppressed or eliminated. If you scratch a child’s leg while someone is putting in an IV, the intensity of the pain can be reduced. The combination of oral versed and a topical anesthetic with a funny face or a cute toy will reduce much of the pain that accompanies modern hospital care for children.

The anatomy and the physiology of the human body that produces, transmits, and perceives the signal allows us to treat pain in a sophisticated manner. When you see a child having trouble, think about all the levels at which the astute clinician can attack the problem.

Rae Brown, M.D., FAAP

                                                      

Rae's Sure Fire Plan...

So here is the rest of my eight point comprehensive plan:


4. Make it alright for people to die - We have a problem with death here in the United States. We overwhelmingly reject it, even when it is for the best. The human body can be sustained long after the patient is gone, and often is. Sometimes this leads to pain that can never be adequately treated and existence that is not life. I am not suggesting that we need to have death panels, but I do believe that physicians should be able to have intelligent discussions with patients and families about the quality of life of the patient and be able to act on these conversations without fear of criminal prosecution.

5. Increase the use of mid level providers - One of the biggest problems that we have here in America is that there are not enough mid level providers. I work with some every day and they are wonderful. Most are careful, committed clinicians with focused skills that provide good service. Here is the rub. We have allowed discussions about who should be paid what to reduce the effectiveness of the use of mid level providers, in some instances. There is room for both - physicians and clinicians that are supervised by physicians; the combination is the best approach because it expands the quantity and quality of care that can be provided. It is difficult to become a physician. The training is long and the requirements for practice are many. It is easier to become a mid level provider. The training is not as long and the requirements are not as arduous. Both have a place in the care of Americans.

6. Change the liability equation - We must change the way we deal with incompetent doctors and with bad outcomes. Many times there is no relationship between the two. Some very fine physicians that care deeply for each and every patient have had bad outcomes with patients. The public is sometimes lead to believe that physicians and nurses are all incompetent and should be punished for bad outcomes. I reject that notion, largely because I  live in the healthcare world and I see people working very hard everyday to make people's lives better. When bad outcomes do happen, maybe we should have a professional panel made up of experts that could determine if there was "fault" on the part of the system that was taking care of the patient. Subsequently, ongoing costs of rehabilitation or care could be assigned to the patient without having an adversarial confrontation.
We must change this because it is a substantial part of the economic equation. The adversarial system raises costs!

7.  Tax things that make people sick - The costs of cigarettes to our economy is far in excess of the amount of tax that is received, both at the federal and the state level. Cigarettes provide us with excess lung disease, heart disease, and cancer. The equation that defines the cost of these diseases can be calculated. That number should be the basis for the tax on cigarettes - the real cost of cigarettes to the economy - and my guess is that is in excess of $10 per pack.

8. Outlaw handguns - I am sorry NRA. From the perspective of a health care provider, this is a no brainer. I have never taken care of a patient that had been injured with a gun that was happy about it. I have never encountered a child that had shot themselves with a parent's weapon that was better for it. I have seen many people that were shot with their guns and most wished they hadn't had them.


So there it is, my "Sure Fire" Plan. Guaranteed to reduce the cost of healthcare for everyone so that we can afford adequate care for all.

Rae Brown, MD

Rae's Sure Fire Plan to Reduce the Cost of Healthcare

Our current expenditure for healthcare in the United States is staggering, but as I have said before, it pales in comparison to that amount that we spend to kill and maim. Some money spent for healthcare is appropriate; healthy workers are more productive and pay more taxes. The system can be much more efficient, however, and  as an insider I have some suggestions that would reduce the cost substantially without affecting quality and without "rationing". This posting will take a while...stay with me!

These are the eights parts to the surefire plan:

1. Focus on wellness - We need to get up and move as a nation. It is almost a national emergency that we don't expend any more energy than we do. This trend shows in increases in weight, diabetes, hypertension, and a variety of other chronic diseases including some forms of cancer. In addition, the AAP has recognized that the number of children that are obese is rising and as one might expect, so has the incidence of diabetes, hypertension and lipid disorders. These children will be sickly adults for a long time and we will pay that bill.
We need an extra hour of school for physical education, more biking and walking trails, incentives to walk or bike to work. In short anything which will incrementally increase the average expenditure of energy by Americans. This is the most important thing to reduce the cost of being sick: don't get sick!

2. Reduce the cost of drugs for patients with public healthcare options. - The federal government could negotiate the purchase of 5 billion simvastatin tablets to treat abnormalities in cholesterol. Since one drug in this class is nearly as good as any other, getting this drug from the government for 5 cents a pill would save Part D of Medicare billions of dollars. Walmart has it right, they have a group of about 100 drugs that treat 99% of patients very well and they sell them to you for $4 a month. By the way, they make a profit.

3. Make the electronic medical record part of the national infrastructure. Our lack of ability to diagnose and treat patients because we don't have the data that we need about trends in their conditions, what hasn't worked for them in the past, what family history is germane to their management, and even what their allergies are has a staggering cost. We miss labs, double order, can't find charts,  basically fly blind in bad weather with the sickest of patients.
A national medical record system will improve the quality of care that we can provide tremendously because it will allow clinicians that are intelligent and well trained to do what they should be able to do - make professional judgements about  the patients medical condition based on evidence without having to guess. Sure, privacy is important, but I am confident that the government that brought you the National Security Agency can figure out how to encrypt my PSA.

More tomorrow...Let me hear from you.

Rae Brown, MD

Sedation for Diagnostic and Therapeutic Procedures

Modern medical diagnostic procedures, such as MRI, have improved our ability to diagnose and manage disease processes in children. These procedures often require a child to be immobile for a prolonged period.  It would be uncommon for an infant or a small child to remain immobile for 30 - 90 minutes unless they are very ill. Because of this, many children, including infants, require sedation for these procedures.

There are risks in sedating children for a diagnostic procedure that are independent of the risks of the procedure itself. Some infants require deep sedation or general anesthesia in order to obtain the conditions that allow for  the best possible result. Sedation for children, even young children, is sometimes not managed by anesthesiologists, the professionals that are trained to do this.

In fact, what you call the person that is managing the sedation is not nearly so important as whether or not they have the skills to deal with an obstructed airway - which is common in the deeply sedated patients. So, if you are a parent, ask.

If you have an interest in issues relating to pediatric sedation, go to wildcatanesthesia.com where you will find, under the subspecialty tag, a comprehensive manual of pediatric sedation prepared by Carrie Makin, RN, BSN and myself.

Rae

The Traumatized Child

My colleagues and I are often faced with the task of taking care of children that have been traumatized. Sometimes a broken child reflects a lack of supervision on the part of an adult. Sometimes the adult is injured with the child. Many times the injury occurs because some adult believes that nothing bad can ever happen - this school of thought appears to be quite common.
Some of the most devastating injuries that I have seen in children have occurred when a child is riding or driving an ATV,  it flips and pins them. Many times these "accidents" are in the field far from medical care and this is a common cause of severe injury and death in the state of Kentucky. When parents see the result of the damage that has occurred, many are incredulous. "It looks so easy and safe on TV."
 Please believe me when I say that as parents, our role is to protect our children until they can protect themselves. Children cannot be expected to make rational decisions about all terrain vehicles, motorcycles, or guns. A four or five year old that is killed or seriously injured because of the lack of supervision of an adult in not an act of God, it is an act of men and women that are not thoughtful. Unfortunately the child is the injured party.

Rae Brown

Important Skills for a Pediatric Anesthesiologist

There are skills intrinsic to the management of children that must be acquired by residents prior to independent practice. These skills, once they have been learned, will make the difference between the enjoyment and dread of the care of children. I have listed many, but not all of these skills below. Use this list as a take off point for discussion with the attending in the operating room.

1. The ability to do a mask induction on an infant or child – A part of learning this skill set is losing the anxiety, which often attends anesthetizing someone without an IV. Some of learning this skill is dealing with something small. This is not difficult. Place the mask on the face. Use a non-pungent potent agent in oxygen. Keep your fingers on the mandible and out of the airway. When the infant is still, put an oral airway in to prevent obstruction by the tongue. Allow the infant to breathe spontaneously if an IV is being placed. Control ventilation if you are trying to attain sufficient depth of anesthesia to place an endotracheal tube without muscle relaxants. A shoulder role sufficient to place the infant’s airway in the sniffing position can be very helpful. Be gentle. It’s a baby.

2. The ability to establish rapid intravascular access – Look in places where there are veins – the saphenous, the cubital fossa, the dorsum of the hand. Look for the best vein before you poke the kid. Retract the skin before the cannula goes through. Use a small catheter for a small vein.  Go slowly.

3. The ability to assess volume loss in infants – Think about how long it has been since the infant had anything to drink. We say NPO after five am, but in reality it may have been twelve hours or more since the baby had any fluids. When was the last wet diaper? Is the baby perky or somnolent? Are the mucous membranes wet? Remember that potent inhalational agents severely depress the myocardium and this especially reduces cardiac output in dehydrated infants. Be very careful.

4. The ability to talk to parents – Try to think about what you would feel like if your baby had to go to the operating room and you were putting the baby’s safety in the hands of a complete stranger. Then sit down and calmly talk to the parents about their child and their worries. Play with the baby. Establish rapport. Talk to the parents about your or your attending’s wealth of experience. Be calm.

5. The ability to assess the airway of an infant – All infants have tough airways because of the small mouth, large tongue and large occiput problem. But some have a small chin, a small mouth or a very large tongue. These children can be a real problem if you don’t recognize this until the muscle relaxants are given.  A good rule of thumb is to look up any syndrome that you are unfamiliar with before it becomes a Wednesday Morning Conference.

6. The ability to recognize a sick child – Sick kids look sick. They are listless, somnolent and glassy eyed. They may be mottled or have cold extremities. Their skin will often have a doughy consistency.
   These infants and children respond poorly to the administration of potent anesthetic agents. Extreme caution should be exercised in the conduct of this child’s care. In other words low doses administered slowly. Often these children are dehydrated. It makes sense to assess the need for rehydration in a sick child prior to administering an anesthetic.

7. The ability to manage the pain of surgery in an infant – Infants and children suffer after painful procedures to the same extent as adults. There are many ways to safely control the pain of surgery without added risk. Become familiar with simple blocks that effectively ablate pain after common procedures in children. Discuss the pharmacokinetics and pharmacodynamics of analgesics in infants and older children.

8. The ability to recognize common postoperative problems of infants and children – Laryngospasm, croup and apnea are the three most common life threatening postoperative problems in infants. These can all be predicted with a remarkable degree of certainty by the clinical situation. Laryngospsm rarely occurs in patients with dry airways in which a non-pungent agent has been used. Sevoflurane is very forgiving. In a patient that is somnolent, has a wet airway or has been exposed to Desfluane, the risk of airway obstruction is great after removal of an endotracheal tube.
   Croup is an inflammatory response secondary to a superimposed infectious process or the placement of a large endotracheal tube in a small airway. Croup is tolerated well by children older than three and not at all by infants. This scenario of airway obstruction and respiratory failure can be eliminated by using a small endotracheal tube and leak testing after every intubation in children less than three. Get your attending to demonstrate a leak test if you are uncertain.
   Apnea and/or periodic breathing are uncommon in infants greater than three kgs and fairly common in infants less than 1500 Gms. Be on the look out!

9. The ability to resuscitate a newborn infant in the delivery room – The ability to oxygenate and ventilate the depressed newborn is key to improving survival. In this regard the effective use of the bag-valve-mask can be life saving. It is uncommon for newborn infants to fail to respond to adequate delivery of 100% Oxygen. If this fails consider long-standing acidosis, volume depletion secondary to blood loss, or a central nervous system catastrophe. 

10. The ability to recognize and treat common life threatening problems in newborns – The common life threatening problems in the delivery room include diaphragmatic hernias, severe meconium aspiration, gastroschisis and omphalocoele. Fortunately, with the use of preterm Echo, it is rare for these diagnoses to be made in the delivery room. Because the diagnosis is not in doubt, plans can be made for airway management and other emergent care before the delivery.
    Meconium aspiration represents the end result of stress and hypoxia in a just delivered infant. Aspirated meconium may produce severe airway obstruction and air trapping sometimes leading to respiratory compromise and death. Meconium can be suctioned out of the airway prior to the first breath. This procedure is probably warranted if an infant has had a long hypoxic period or has a large amount of thick meconium in the amniotic fluid. Infants that are vigorous at birth or have thin, non-particulate “pea-soup” meconium do not require direct laryngoscopy before the first breath.

Continued: what do parents need to know?

More about the information that parents should have before their child has a surgical procedure:

Question: Is this facility capable of managing the patient if the unexpected happens?

Largely because of the drive to cut cost, but also because of pressure applied by surgeons and others to do every known case, many facilities are not staffed or equipped to manage infants  and older children that have complex chronic disease. Case in point is the child that has pyloric stenosis. Many small rural medical centers are pressured to take care of these infants without the resources, personnel or equipment, to do so. For most children that are healthy and older than three or four simple surgical procedures can be managed in almost any accredited medical center or ambulatory facility. For the young and the sick, this is not true. Parents have to ask the specific question " Is this facility prepared to manage my child if there is an untoward event?" Is there a resuscitation plan for children? How many children do you take care of? Be skeptical of the answers if they don't pass the "sniff"test!

Question: What are the risks of Anesthesia for my child?

After a child is three years old and if the child is healthy the risks of general anesthesia approach those of healthy adults. Over the last twenty years the mortality statistics for anesthetized patients has dropped tremendously. This is because of better training, better technology, and enforcing high standards. So thirty years ago the risk of death for a healthy person was about 1: 100,000 and in 2009 the risks are greater than 1: 2,000,000. Yes we do have a good health system.
For  infants and sick children, the risks are greater, and the statistics will vary with the acuity level of the patient. But this is the issue, the mortality statistics for infants vary with the training and experience of the person that is taking care of them. In my mind, this is not a guarantee of an outcome, but it does suggest that little ones should be taken care of by those that have the specific training to do what needs to be done. Most children's hospitals and academic medical centers have fellowship trained pediatric anesthesiologists. It makes a difference and if your child is less than two years old or has serious co-morbid conditions, then as a parent you should ask about the training and experience of the people that present themselves to you.


Rae Brown MD

Questions that parents should ask when their children have an operation

The lack of information about what Pediatric Anesthesiologists do and how one defines quality frightens many parents. Moms and Dads often say " I am more scared about the anesthesia than the surgery." It is part of my job to explain the risks and benefits and, to the best of my ability, allay some of the anxiety and fear. In this posting, I hope to give some guidance about what parents should want to know before their child goes off with a stranger to the operating room? This may take a couple of postings so put your seat belt on!

1. What experience and training does the practitioner have in the management of infants and children?

Most board certified anesthesiologists have received significant pediatric training during their residencies. After going into practice some develop a niche in managing children; millions of tonsillectomies and hernia repairs are managed by general anesthesiologists safely every year. The overwhelming majority of these practitioners provide high quality and safe care.
Infants, especially newborns, the premature and children with chronic disease require specialized training and should be cared for in centers that have the resources to provide the ancillary support that is required. For these patients, there is a difference in outcomes and parents of these kids should inquire about the training and experience of the person that will be managing the child's care.

2. Specifically how are Pediatric Anesthesiologists trained?

 Most have five years of graduate training in anesthesiology after medical school including a fellowship in the management of the sickest children. Some have substantially more training - some are board certified in Pediatrics, many have substantial additional training in critical care. Is this necessary? Maybe not, but the more training and experience that a physician has the greater the likelihood that they can " land this baby in bad weather", and for some of the sickest infants, the weather is more like landing in a hurricane.

So parents should feel at ease asking about the experience level of the anesthesia practitioner, especially if their child is chronically ill or premature. In the same way that they should investigate the credentials of  a surgeon, parents have a responsibility to ascertain that the person that will manage their most treasured possession meets or exceeds all suitable standards.

More about this in my next posting

Rae

Universal Health Care in the United States

I am a physician and I think that everyone should have the best healthcare that we as a country can provide. I recognize that personal responsibility would have to be a part of the equation - with taxes on sugar, fat, . cigarettes and alcohol. But it is beyond me why we can spend a trillion dollars in Iraq and cannot provide universal healthcare for our citizens. Let's be clear about this, the United States is the only industrialized country that doesn't have healthcare for all. In this regard we are the pariahs.

Healthcare is certainly an industry, providing jobs and creating value. When we spend money on medical research or on making people more productive it is an entirely positive thing - the exact opposite of the military industrial complex. When we teach people to be nurse and doctors and technicians, we are creating stable employment opportunities within our economy. As we try to turn the United States from a boom and bust economy to one with steady stable growth, we could do worse than expand the healthcare industry, in a controlled fashion so that every child, every working person and every elderly person could get the same physical and mental health support that is availed of our congressmen and women.

I think that every physician in the United States probably has ten ideas to make healthcare more effective and efficient, reducing costs so that more care could be provided to those that have little or none now. I also know that providing this care will ultimately mean that I will pay more to the government, and I am fine with this. You see, I take care of people every day that wait until a disease process is virtually untreatable to come to the attention of the healthcare system. Many times this is because of the costs involved and the lack of a stable , affordable insurance product for those that are involved in self employment and small business. These are not welfare cheats...these are the working middle class. That everyone else in the industrialized world has recognized this and that we haven't  makes me sick and it is time for all of us to step up and think about the common good.

Rae Brown, MD

Pyloric Stenosis

They talk about the stroke belt, an area in the southeastern United States where many develop hypertension and diabetes. This is thought to be because of the historically large amount of cholesterol containing fried foods. Well, we live in a pyloric stenosis belt and I don't think it is because of what babies eat.

Pyloric stenosis represents hypertrophy of a muscular band at the outlet of the stomach. These patients, usually boys, begin to vomit during their first two months of life. Because of the obstruction to outflow from the stomach, these babies become dehydrated and develop a metabolic alkalosis. Most are diagnosed within the first week after they begin to vomit. This reduces the amount of dehydration, but the infants inevitably need substantial IV fluids before coming to the hospital.

The surgical treatment of patients with pyloric stenosis is straight forward. the anesthetic management is not. Infants still die in the United States because of attempts to manage cases in medical centers that have little to no experience with newborns. This is usually because a surgeon feels that they can take care of a child but doesn't consider the other health care professionals involved in the babies management. This case should only be done in centers that have substantial experience with babies and especially anesthesiologists that take care of infants as a regular part of their practice.

I have written several things on the Infant with Pyloric Stenosis. You can find them at Wildcat Anesthesia.com in the Pediatric Anesthesia Subsection.

Rae Brown, MD

Talking to Parents

I have said this many times, but I think it is worth repeating. Sit down when you go to talk to parents. Take your time and get to know them and their child - your patient. It reduces their anxiety and when that happens the child's anxieties may be diminished. Parents also respond well to clinicians that can engage children. I find that the best way to do that is to sit at eye level with the child and talk to them in a soft voice. It really doesn't matter what you say - hence my questions to three year olds about their explanations of complex economic concepts...like credit default swaps. In my mind the three year olds give more intelligent answers than the pundits.
Rae Brown, MD

Mediastinal Masses

Sanjay,
Thanks for looking at the Blog. I hope that you will encourage your friends to post questions and topics that they might be interested in talking about.
Your suggestion that muscle relaxants are not used comes from the experience that decompensation often occurs when patients are paralyzed. The reason is likely multifactorial, but an increase in the mean intrathoracic pressure associated with positive pressure ventilation discourages the return of intravascular volume to the right side of the heart. In the scenario of a large mass that may encapsulate the pericardium, the patient's ability to maintain cardiac output is limited. In addition, the dynamic forces that maintain a patent airway in the spontaneously ventilating patient are eliminated in a patient that is paralyzed, sometimes producing significant intrathoracic airway obstruction.
Given these issues, what do we need to know about these patients before we put them to sleep?

First Topic: How do we really manage patients with mediastinal masses?

Mediastinal masses are common in pediatric anesthesia practice. Many practitioners fear patients that present with a mediastinal mass because of the risk of cardiovascular collapse and inability to ventilate that has been reported. There is a lot of folklore that has been written about the evaluation and management of these patients. The question is what do people really do? Let me hear from you.

What you must know about malignant hyperthermia.

Everything That You Must Know About Malignant Hyperthermia
Rae Brown, M.D.

Malignant hyperthermia is a pharmacogenetic disease process. The manifestations of the disease occur when predisposed individuals are exposed to a small number of drugs. Most of these “triggering agents” are general anesthetics. Succinylcholine and all of the potent inhalational agents have been implicated – including xenon.
MH occurs because of a defect in the calcium sensitive ryanidine receptor - RYR1. This receptor is found in all skeletal muscle, smooth muscle, neurons, and in B-lymphocytes. In skeletal muscle, the RYR forms the footplate between the transverse tubules and the sarcoplasmic reticulum. Calcium homeostasis is mediated through these receptors and defects can produce massive outpouring of calcium during excitation contraction coupling. Because skeletal muscle contains a large percentage of the intracellular calcium in the body, failure of regulation creates exaggerated contraction, a hypermetabolic state, with an elevated temperature and subsequent severe acidosis. This is the clinical picture that is called malignant hyperthermia.
A specific point mutation in the RYR1 has been associated with MH. However, only about a third of the patients with MH will demonstrate this specific point mutation. RYR1 is a very large protein, the largest known receptor in the body. It is likely that other point mutations will be found that produce the same clinical effect.
There is one very sensitive test for malignant hyperthermia – the caffeine halothane contraction test. This test will be positive in more that 97% of patients that have true MH and is 78% specific. This includes patients with known point mutations in the RYR1 protein that are known to be associated with MH as well as those that do not. For this reason, the CHCT is the only test that is available that is reliable/specific/sensitive. Molecular genetics testing will demonstrate the point mutation that is known in the RYR1, but will miss the other 65% of patients. Molecular testing is appropriate for relatives of a proband that has had molecular genetic testing that is positive. Otherwise, it should not be used as a screening test.
The CHCT is difficult to perform and can only be performed on fresh muscle. There are currently only five centers in North America that are certified to do this test. The number of centers is kept to a minimum in order to improve the specificity of the test. The center that is closest to Lexington is in Winston-Salem, NC. Because the multiple fascicles that are required to perform the test, it would be uncommon for a child under 40 kg/ten years old to present for testing.
MH may randomly present associated with any disease process. In the past, an association between strabismus and MH was shown to represent a statistical error caused by the increased likelihood that these patients would present for surgery. There are very few disease processes that are now recognized as being tightly linked to MH. In the future, this number may decrease further as we understand more about the genetic basis for the disease. Presently central core disease, hypokalemic periodic paralysis, and King-Denborough Syndrome, a combination of facial dysmorphic features with MH, are the only disease processes that seem to manifest the hypermetabolic state with exposure to anesthetics. For these patients, at present, all should be managed with nontriggering techniques.
The association between muscular dystrophy and the hyperkalemic cardiac arrests associated with the administration of succinylcholine represent an entirely separate pathophysiology, but can be equally as deadly. The presence of a large number of cases of cardiac arrest in infant boys, later found to have muscular dystrophy, is the primary reason that succinylcoline is not routinely used in the United States.
Malignant hyperthermia presents as a profound hypermetabolic response. Early indicators include tachycardia, rapid increases in end tidal carbon dioxide despite seemingly adequate ventilation, and rigidity. Despite its name MH rarely presents with an elevation in temperature as the first and/or only manifestation of a crisis. Continued exposure to the causative agent, however, will accelerate the disease process and early reversion to nontriggers as the primary anesthetic is a key to the resuscitation of the patient.
Immediate treatment with dantrolene can be life saving. This medication should be prepared and given quickly after a presumptive diagnosis is made. Dantrolene inhibits the release of calcium from the sarcoplasmic reticulum of skeletal muscle. This is accomplished by limiting the activation of the RYR. Though dantrolene does not act at the neuromuscular junction it will produce profound muscle weakness. Patients treated during the preoperative period with prophylactic dantrolene have aspirated because of this effect and there is no evidence that use of the drug prior to an exposure to a triggering agent is better than after exposure.
There are several keys to successful resuscitation of patients with MH:
1. Vigilance allows the savvy clinician to recognize the clinical scenario early in its course. Good anesthesiologists are suspicious and will note the association of tachycardia, increasing carbon dioxide, and possibly rigidity for what it is.
2. Early elimination of triggers and administration of dantrolene is very important. Dantrolene is difficult to prepare and extra hands are always necessary. It will require more than one person to prepare dantrolene alone. Currently, a bolus of 2.5 mg/kg as a first dose is recommended, with subsequent boluses of 2.5 mg/kg, administered until the patient is stabilized.
3. Secondary cooling of the patient is important, but should not prevent or slow the preparation and administration of dantrolene. Time and resources are often wasted running for ice and getting rafts, when the primary drug for resuscitation sits unopened.
4. If there are sufficient resources to prepare dantrolene and provide the resources to cool the patient, then this can be done with cool IV fluids or saline lavage of the bladder or stomach.
5. Further treatment is symptomatic and includes response to acidosis, arrhythmias, electrolyte disturbances, and excess myoglobin production caused by muscle destruction with subsequent acute renal failure.
6. Patients that manifest and are treated for MH should be monitored and treated in an intensive care setting postoperatively. It is recommended that patients be treated with dantrolene for 24 hours after metabolic stability returns. The MHAUS recommends a dose of 1 mg/kg every 4 to 6 hours. In addition, because of the risk of recrudescence of MH, patients should be monitored for at least 24 hours after the last dose of dantrolene is given.
Patients that have had an episode of MH, with first degree relatives that have had a clinical incident strongly suggestive of MH, those with a positive CHCT, or who have had molecular genetic testing demonstrating the point defect in RYR1 that has been tied to MH, should subsequently have nontriggering anesthetics. This can be accomplished with virtually any agent normally used by the anesthetist, with the exception of succinylcholine and potent inhalational agents. Patients have been successfully anesthetized as out patients, for labor and delivery, and with regional anesthesia.
Neuroleptic malignant syndrome is a rare, but life threatening idiosyncratic response to a neuroleptic medication. Though the clinical picture emulates MH with rigidity, fever, and autonomic dysfunction, NMS is mediated through the blockade of dopaminergic pathways within the central nervous system. Drugs such as haloperidol, thorazine and resperidone can produce the picture of NMS as well as phenergan, droperidol, and metaclopramide. Treatment with dantrolene is not specifically indicated, but withdrawal of neuroleptics and symptomatic management of rigidity (levodopa/carbodopa), respiratory failure or renal failure is necessary.
Masseter muscle rigidity, also called masseter spasm, is usually associated with the administration of succinylcholine. It has been suggested that this may be an early sign of MH. Masseter spasm with associated elevations in carbon dioxide or fever should be treated as MH
MHAUS, The Malignant Hyperthermia Society of the United States, has an excellent web site, which provides up to date information about testing, diagnosis and treatment.
Rae Brown, MD
Department of Anesthesiology
University of Kentucky Medical Center
Kentucky Children’s Hospital

How do we know that we have the endotracheal tube in the center of the trachea

How Do We Know That the Endotracheal Tube Has Been Positioned Correctly in the Trachea?

The correct placement of the endotracheal tube ( ETT) in the trachea is one of many important issues that face the anesthesia care provider daily. The practitioner that manages the care of infants, the issue becomes even more critical. The distance between the laryngeal inlet and the carina is short. In children up to one year of age this distance varies from 5 to 9 cm.
The tolerance for one lung ventilation in infants is limited as the FRC is small relative to the utilization of O2. Our ability to determine placement by listening to breath sounds is limited by the small size and the rounded configuration of the infant chest. Generalized transmission of sound is the norm and unless there is essentially no background noise, a truly accurate assessment rarely occurs.
Many authors have created formulas to determine the placement of the tip of an ETT in the mid trachea of a child. Most, if not all of these formulas apply to children that are more than two years of age. (Age in years/2 + 12; or weight in kg/5 +12) and are not useful for infants. The gold standard, of course, would be direct visual placement of the tip of the ETT in the exact mid trachea as measured via radiograph or bronchoscope. Practically speaking, visualizing the lines on the ETT as it passes through the cords represents a reasonable approximation of the gold standard. However, a view of the glottic inlet that is partially obstructed may inhibit this method to some extent.
A reasonable method for initial placement of the tip of the ETT in infants is the 7-8-9 rule. This rule adds 6 cm. to the infants weight in kg. (A 1000 gram infant would have their ETT taped at 7cm at the lip.) In a recent study utilizing this technique, 25% of infants up to 3 Kg in the nursery at Rainbow Babies and Children’s Hospital required adjustments in the initial placement. In addition, there was substantial variability between the percentages of correct placements with 2. 5 and 3.0 endotracheal tubes. In a recent study published in Anesthesia and Analgesia three methods of positioning were compared – Pulling the tube back from the rt. mainstem while listening, placing the prescribed marks at the level of the vocal cords, or by palpating the ETT in the suprasternal notch. In each the position was validated using fiberoptic bronchoscopy. In this study the visualization of marks at the level of the cords was nearly universally associated with correct placement and there were no associated endobronchial intubations in this group when the head was flexed. Similarly, there were no inadvertent extubations with extension.
So, this is what I think that we can learn.
1. The distance between the cords and the carina in infants less than one year of age is short and variable depending on variables such as the post conceptual age at the time of delivery, the nutritional and growth state of the child after delivery, and the presence of aberrations of growth such as dwarfism.
2. The best method for determining the placement of the tip of the ETT in a clinical situation is to watch the marks on the as they go through the cords and verify your effort using the 7-8-9-rule.
3. A major source of variability is the size of the ETT that is going through the larynx – smaller than is appropriate for the size of the larynx will leave the tube high, and larger than appropriate will risk endobronchial intubation. In some infants that have subglottic stenosis the ETT that would seem appropriate for the size of the child will be inappropriate for the size of the airway.
4. There are rules, and there are rules but airway catastrophes are by far the leading cause of morbidity in small children. No matter what rule you have learned be suspicious of the airway in every infant and vigilant for changes in any ventilatory parameter.

Rae Brown, MD
Professor of Anesthesiology and Pediatrics
University of Kentucky Medical Center