"Jonathan Swift said, "Argument is the worst sort of conversation." For the most part, this makes good sense. However, too often medical education is a onesided, passive process. Medical students and residents attend innumerable lectures during which information is "downloaded." Residents are rarely exposed to two or more subspecialists in the same room discussing management, much less disagreeing. They often express discomfort when confronted with professional dissension, unable to grasp the possibility that a single universal Truth does not exist. Moreover, the Herculean task of bringing multiple subspecialists together in a single room for a patient discussion is a huge barrier to providing this type of dialectic in medical education.
Fortunately, many of these problems were solved at The Children's Memorial Hospital, Chicago, Illinois, by the institution of Firm Rounds in 1993. This concept was imported from Children's Hospital Medical Center of Cincinnati by Marty Myers, MD, when he became chairman of the Department of Pediatrics. Each week, members of the Department of Pediatrics convene to discuss a single case in-depth, with at least one representative from each subspecialty in attendance. This has become the premier teaching conference of our department, as much for the discussants as far the residents and medical students in the authence. Over the years, the conference has evolved to include radiologists, pathologists, and pediatric surgeons. Although not the original intent, many patient care decisions and new diagnoses have been made as a result of this "meeting of the minds." The name "Firm Rounds" refers to the British system in which a dedicated group of physicians care for patients as part of a "firm."
This month, Pediatric Annals introduces a new feature, "Firm Rounds at The Children's Memorial Hospital, Chicago. " Although most of the badinage and verbal repartee has been omitted (unfortunately), what's included is a concise reporting of a case and the ensuing discussion. It is hoped that these case discussions will stir some debate within your own practice and be educationally valuable. As Bertolt Brecht has said, "The world of knowledge takes a crazy turn, when teachers themselves are taught to learn."
A 14-month-old boy was transferred from an outside hospital for an apparent life-threatening event. On the day of admission, shortly after eating, he vomited several times and appeared to stop breathing. His limbs became stiff and his eyes rolled upward. He was unresponsive to verbal stimuli and became blue around the lips. The entire event lasted approximately 2 minutes. He remained sleepy for approximately 90 minutes after the event. A review of systems was otherwise negative.
Birth History: He was a 6pound, 11-ounce product of a full-term vaginal delivery without any perinatal complications.
Medical History: He was hospitalized at 3 weeks of age with a respiratory syncytial virus upper respiratory tract infection.
Diet: He breast feeds 4 to 5 times each day for approximately 15 to 20 minutes and eats a widely varied toddler diet. In addition, he drinks approximately 6 to 12 ounces of water and 4 to 6 ounces of apple juice daily.
Family History: Normal.
Physical Examination: His vital signs were unremarkable. His weight was 8.6 kg, length 71.5 cm, and head circumference 43 cm, all less than the 5th percentile. His weight-to-height ratio was in the 25th percentile. Previous growth points were unavailable. He looked well and the results of his physical examination were entirely unremarkable.
Robert Listernick, MD, moderator: What is your definition of an apparent life-threatening event?
Oren Lakser, MD, pediatric pulmonologist: Essentially any event during which a parent or caretaker is frightened and feels that a child is in imminent danger of dying. This would include episodes when a child stops breathing, turns color, or apparently chokes. Similar to sudden infant death syndrome (SIDS), the peak age is approximately 2 months, but usually during the first 6 months of life.
Dr. Listernick: What are some of the conditions associated with apparent life-threatening events?
Dr. Lakser: Often what the parents report as abnormal actually isn't abnormal by our definitions. In normal infants, periodic breathing and up to 20 seconds of "apnea" are considered normal. Some infants occasionally choke during eating. Although this is entirely normal, parents who have not seen it before may become scared. Of course, infants who have recurrent choking episodes associated with feedings may have H-type tracheoesophageal fistulae, laryngeal clefts, or swallowing abnormalities.
Following this, there are a host of pathologic entities that have been associated with recurrent apparent life-threatening events, including gastroesophageal reflux, seizures, sepsis, cardiac dysrhythmias, vascular rings, airway abnormalities, and others.
Dr. Listernick: My sense is that a good history and physical examination will detect most of the diagnoses on this list, obviating the need for an extensive evaluation. For all the children who are admitted to this hospital with a diagnosis of an apparent life-threatening event, 99% go home with a diagnosis of either gastroesophageal reflux or a "choking episode."
What is the relationship between gastroesophageal reflux and apnea?
Dr. Lakser: If you review the literature, most studies suggest that gastroesophageal reflux is often found in patients who have apparent life-threatening events. However, simultaneous polysomnography and pH probe results generally fail to show a temporal relationship between the two. We don't necessarily understand the entire physiology of how it happens, and just because there's a 15-rninute time lag between the apnea and when the reflux seems to register doesn't necessarily mean they're not associated. Despite this, the correlation between reflux and true apnea is tenuous at best.
Dr. Listernick: How do you decide whether a child has had a seizure?
Kent Kelley, MD, pediatric epileptologist: An accurate history will give the answer 95% of the time. Historical characteristics suggestive of seizures include sudden onset, stereotypical nature, repetitive events, localized motor asymmetry, and a change in level of interaction or consciousness. Although generalized convulsions can occur in this age group, particularly in the form of febrile seizures, the predominant seizure types in children younger man 1 year are going to be partial seizures and infantile spasms. If this child had a true generalized convulsion, you would have expected tonic stiffening followed perhaps by some bilateral repetitive movements. Now that we're able to witness more seizures than ever before with the aid of video electroencephalogram (EEG) monitoring, we realize that they're more complicated than we used to think by description.
Dr. Listernick: Does the history of a "post-ictal" period help?
Dr. Kelley: Unfortunately, many episodes that are described as post-ictal wind up not being associated with an ictal event. Here, you have a child who vomited, stopped breathing for a period of time, and then was "out of it." Thaf s not very specific for a seizure.
Dr. Listernick: Should an EEG be part of the evaluation of a child with an apparent lifethreatening event?
Dr. Kelley: It really depends on the history. A 6-month-old infant with either stereotypical or repetitive events or a hypomotor seizure with cyanosis should definitely undergo an EEG. Although I would probably recommend an EEG for this child if no other etiology were discovered, I would expect it to be normal.
Dr. Listernick: If a seizure were a diagnostic consideration in this child, what evaluation would he have had if he had come to our emergency room?
Dr. Karen Sheehan, pediatric emergency room physician: This child is conoerning in that he may be failing to thrive. Our clinical pathway would dictate that the healthy child older than 6 months who is developmentally normal and who has completely normal physical and neurological examinations would require no further evaluation in the emergency room. Rather, he would be referred to see our epileptologists within 1 week. Many studies have shown that the likelihood of finding any metabolic abnormalities or mass lesions on neuroimaging if all these conditions are met is extremely low. Of course, if follow-up of the patient is not assured, the evaluation might change.
Dr. Kelley: If the history were suspicious for a seizure, we would see him, repeat a history and examination, and perform an EEG. Interestingly, more than 25% of children who have been screened by our emergency room as a first-time seizure have not had seizures by our evaluation. This highlights how difficult it is to obtain an accurate history. Because a normal EEG doesn't preclude the existence of seizures, close follow-up is of extreme importance.
Dr. Listernick: This child was actually seen at an outside emergency room initially and felt to have had a seizure. They found that his serum total calcium was 6.3mg/dL.
Dr. Douglas Nordli, pediatric epileptologist: I just want to reinforce the role of the task force recommendations. The idea is to liberate physicians from feeling the need to do unnecessary testing. However, we should always try to learn from each test case. In this case, the child's potentially poor weight gain and growth as evidenced by his growth parameters should have been a red flag.
Dr. Listernick: Now that we know he is hypocalcemic, what did his apparent life-threatening event represent?
Dr. Kelley: He may have had muscular tetany with carpopedal spasm, laryngospasm, and upper airway obstruction or a true seizure.
Dr. Listernick: Why is this child hypocalcemic?
Dr. Richard Conn, pediatric nephrologist: The differential diagnosis would include primary hypoparathyroidism, possibly associated with DiGeorge syndrome, hypomagnesemia, vitamin D deficiency, and kidney failure.
Dr. Listernick: Is DiGeorge syndrome likely to present at 14 months of age?
Dr. Cohn: There is a spectrum of disease, including variable degrees of immunodeficiency, cardiac defects, dysmorphic features, and parathyroid function.
Dr. Listernick: What accounts for the hypocalcemia sometimes seen in kidney failure?
Dr. Cohn: Generally, if s due to a combination of phosphate retention related to altered kidney function and decreased proximal renal tubular production of 1,25 dihydroxy vitamin D.
Dr. Listernick: How should mis child be evaluated?
Dr. Cohn: An ionized calcium should be performed to verify true hypocalcemia. If confirmed, testing should include at least electrolytes, blood urea nitrogen (BUN), creatinine, phosphorus, alkaline phosphatase, parathyroid hormone, and vitamin D levels.
Dr. Listernick: It's important to point out that this child presents with a naturally occurring diagnostic challenge. If a patient is hypocalcemic, ifs essential to obtain the relevant laboratory tests (parathyroid hormone and vitamin D levels) before therapy is instituted. The same is true when faced with a hypoglycemic child; all the essential laboratory evaluation ideally should be obtained before the correction of the hypoglycemia.
The electrolytes were normal, BUN was 6 mg/dL, creatinine was 0.4 mg/dL, ionized calcium was 0.72 mM/L (normal: 1.08-1.34 mM/L), albumin was 4.1 g/dL, phosphorus 4.1 mg/dL, alkaline phosphatase was 765 IU /L, and the magnesium was normal.
Dr. Cohn: Our initial impression was that this child had vitamin D deficiency. X-rays of the wrists and knees displayed widened, frayed metaphyses characteristic of rickets.
Dr. Listernick: Why are there no signs of rickets on the physical examination?
Dr. Cohn: I actually thought that this child had mild thickening of the wrists and the knees. To see tibial bowing, the child has to be growing; for the past 4 to 6 months, I suspect that this child did not grow well.
Dr. Listernick: How do we confirm vitamin D deficiency?
Dr. Cohn: You would measure circulating levels of 25-hydroxy vitamin D and 1,25 dihydroxy vitamin D. This child's 25hydroxy vitamin D level was very low and his 1,25 dihydroxy vitamin D level was normal. The latter is normal because the kidneys are avidly converting what little 25-hydroxy vitamin D is circulating into active 1,25 dihydroxy vitamin D under the stimulus of parathyroid hormone.
Dr. Listernick: So why is mis child vitamin D deficient if he has been receiving adequate amounts of breast milk?
Dr. Cohn: Essentially, every nutrient required by infants during the first 6 months of life is present in breast milk save for vitamin D. If the infant spends a lot of time outside and is light skinned, there will be sufficient exposure to ultraviolet light so as to synthesize enough vitamin D. However, there has been a recent resurgence of reports of vitamin D-deficient rickets in exclusively breastfed African American infants. This mother's vitamin D levels were normal, further proof that vitamin D deficiency may occur in the infant independent of the status of maternal stores.
Dr. Listernick: What is the American Academy of Pediatrics' (AAP' s) recommendation regarding breastfeeding and vitamin D?
Sharon Robinson, MD, chief pediatric resident: The only recommendation that I can find is mat vitamin D supplementation should be considered in infants who lack sun exposure, or in infants whose mothers don't have a lot of dietary vitamin D.
Dr. Cohn: A great deal of consideration has been given to rewriting this, because ifs now believed that vitamin D should always be supplemented in exclusively breastfed infants.
Dr. Listernick: Although we don't have his growth chart, he's clearly below the fifth percentile in weight. I wouldn't be surprised if he was receiving a hypocaloric diet, despite the dietary history. Ifs difficult to assess the adequacy of the breastfeeding. In addition, he was clearly iron deficient, with a hemoglobin of 9 g/dL and a mean corpuscular volume of 61.
Dr. Robinson: The AAP clearly recommends the introduction of iron-containing solid foods during the second 6 months of life in all breastfeeding infants.
Dr. Listernick: Given this child's presumed poor weight gain, iron deficiency anemia, and vitamin D deficiency, is there any reason to think that he may have a malabsorption syndrome?
Dr. Karen Emerick, pediatric gastroenterologist: Vitamin D malabsorption may be part of a more generalized fat malabsorption in association with either liver parenchymal disease, biliary tract disease, or pancreatic insufficiency. Fat is malabsorbed in liver diseases due to inadequate delivery to the intestines of bile salts, which are needed to emulsify and digest fat. Inadequate cellular bile acid transport may occur in familial cholestatic syndromes or conditions that lead to obstruction of bile flow. Lack of pancreatic enzymes, as in cystic fibrosis, similarly affects fat digestion. Given that this patient did not have hepatomegaly or evidence of cholestasis, fat malabsorption based on liver disease seemed unlikely. Pancreatic insufficiency was theoretically possible, but I would first determine whether the infant received adequate calories and vitamin D in his diet before I suspected malabsorption.
Dr. Listemick: A sweat test was normal. What about the possibility of celiac disease?
Dr. Emerick: Generally, children with celiac disease are ill appearing and wasted; they often have bloated abdomens and signs of both carbohydrate and fat malabsorption, including hypoalburninemia.
Dr. Listernick: Just to be clear, we don't have any points on his growth chart, so we really can't make any definitive statements about his nutritional status other than the fact that his weight-toheight ratio was normal and mat we had a normal serum albumin. Finally, whaf s the treatment of this child's hypocalcemia and vitamin D-deficient rickets?
Dr. Cohn: Vitamin D. We administered Drisdol® (ergocalciferol), which is vitamin D that is not hydroxylated at either the 1 or the 25 position, at a daily dose of 4,000 U. In addition, he will receive 250 mg of elemental calcium four times daily for approximately 1 month.