# Pediatric Critical Care Review Hasan Pappas

1. Match the metabolic abnormalities listed (A-D) with the specific corresponding disorder below: Metabolic Lactic Acidosis Ketosis Hyperammonemia Acidemia A. - - +++ - B. ++ + + - C. + + - - D. +++ + - +++ ____ Organic acidemia ____ Maple syrup urine disease ____ Urea cycle defect ____ Congenital lactic acidosis Click here for answer 2. All of the following statements regarding hyperammonemia in infants are true except: A. In children, cytotoxic cerebral edema and increased intracranial pressure may occur B. Its toxicity is reversible C. Ammonia is normally detoxified in astrocytes by glutamate dehydrogenase and glutamine synthetase D. The pronounced depletion of adenosine triphosphate in the brain reticular activating system accounts for the altered level of consciousness E. There is an active urea cycle within the brain Click here for answer 3. A newborn baby girl was a product of a full-term spontaneous vaginal delivery after an uneventful pregnancy and is noted to have recurrent intractable clonic and myoclonic seizures that have been resistant to therapy. The baby has been breast fed only twice and has been afebrile. Sepsis workup has been negative so far. Arterial blood gases, blood glucose and blood ammonia and serum urine ketones have all been within normal limits. At this juncture, one should think about: A. Ornithine transcarbamylase (OTL) deficiency B. Methylmalonic acidemia C. Non-ketotic hyperglycinemia D. Maple syrup urine disease E. Congenital lactic acidosis Click here for answer 4. All of the following statements are accepted hypotheses of hepatic encephalopathy except: A. Synergistic effects of accumulation of toxins with coma producing potential B. The false transmitter hypothesis C. The neural inhibition of gamma-aminobutyric acid D. Professor Mertz revelation Click here for answer 5. All of the following statements are true regarding the neuropathology of metabolic encephalopathy except: A. Infarction is usually present with hypoglycemia B. Hypoglycemia causes superficial cortical layer necrosis C. Proliferation of the protoplasmic astrocyte (Alzheimer type II astrocyte) occurs D. Degenerative changes of cortical layers 5 and 6 develops Click here for answer 6. Match the following therapeutic interventions with the corresponding disorder it is intended for: A. Arginine hydrochloride B. Biotin C. Vitamin B12 D. Thiamine E. Riboflavin ____ Multiple carboxylase deficiency ____ Hyperammonemia due to urea cycle defects ____ Methylmalonic acidemia ____ Maple syrup urine disease ____ Multiple Acyl-COA dehydrogenase deficiency Click here for answer 7. A 13-year-old female with a history of chronic adrenal insufficiency presents to the Pediatric ICU with a BP of 60/30 mmHg and a heart rate of 125/min. All of the following suggest adrenocortical insufficiency except: A. Hyperkalemia B. Hyponatremia C. Hyperglycemia D. Hypercalcemia E. Anemia Click here for answer 8. Diabetic ketoacidosis is associated with insulin deficiency with elevation of all of the following hormones except: A. Growth hormone B. Glucagon C. Somatostatin D. Epinephrine E. Glucocorticoids Click here for answer 9. Match the following answers with their correct descriptions: pH PCO2 PaO2 HCO3 A. 7.38 66 45 35 B. 7.04 18 120 5 C. 7.25 15 124 7 D. 7.15 78 60 26 E. 7.35 80 35 35 1.____ A 16-year-old female with new onset diabetic ketoacidosis 2. ____ A 12-year-old with cerebral palsy having severe scoliosis and excessive emesis due to bowel obstruction 3. ____ A 15-year-old male presenting with paresis after eating strawberry jam that is over 1 year old 4. ____ A 16-year-old female who recently separated from her boyfriend and came to the ER with nausea, vomiting, tinnitus, abdominal pain, and agitation Click here for answer 10. All of the following statements regarding the rapid ACTH stimulation test are true except: A. A blunted cortisol response can be due to primary or secondary adrenocortical insufficiency B. This test is only a screening procedure C. A normal response eliminates the possibility of primary adrenocortical insufficiency D. A normal response eliminates the possibility of secondary adrenocortical insufficiency Click here for answer 11. In sick euthyroid syndrome, all of the following statements are true except: A. There is a decrease in serum T3 levels B. 30-50% have low T4 levels C. There is a high TSH level D. There is an increase in reverse T3 level Click here for answer Answers 1. B, C, A, D Slight elevation of ammonia is noted with organic acidemias, however, this is usually minimal compared to the significant hyperammonemia that is noted with urea cycle defects. Maple syrup urine disease (a disorder of branched chain amino: lencine, isolencine, and valine) is characterized by metabolic acidosis and ketosis and significant hypoglycemia. The level of lactic acid will be significantly elevated with congenital lactic acidosis. (Fuhrman BP, et al. Pediatric Critical Care, 2nd Edition; pp 820-825) 2. E Urea cycle is present and is active only within the liver. In the brain there is no urea cycle that can detoxify ammonia. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1299-1302) 3. C In a newborn who develops significant seizures within the first 24 hours after birth, prior to having consumed a significant amount of protein in the diet and who does not have significant metabolic acidosis or elevation of ammonia levels, one has to think about non-ketotic hyperglycinemia. OTL deficiency is an x-linked disorder of ureacyte and is usually associated with significant elevation of blood ammonia levels. Methylmalmic acidemia, propionic acidemia, and isovolemic acidemia are organic acid disorders and are usually characterized by high anion gap metabolic acidosis. Maple syrup urine disease is discussed Question #1, and is a disorder of branched chain amino acids due to defective branched chain ketoacid dehydrogenase. Management of glucose and pH is most important in these patients. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1299-1302) 4. D All other responses are appropriate. The accepted hypotheses include: 1) The synergistic neurotoxin hypothesis which states that hepatic encephalopathy (HE) results from the synergistic accumulation of toxins, including ammonia, mercaptans, and short chain fatty acids. 2) The false neurotransmitter hypothesis states the Octopamine acts as a false neurotransmitter and is taken up and released by neurones that normally store norepinephrine and dopamine. 3) The neural inhibitory hypothesis implicates GABA in the pathogenesis of HE. (Jones, EA. The neurobiology of hepatic encephalopathy. Hepatology, 1984; Vol. 4:1235) 5. A Hypoglycemia produces selective necrosis of the superficial cortical layers sparing the non-neuronal elements (unless hypoglycemia is profound and prolonged). Infarction is usually abent even after severe hypoglycemia. In Reye’s syndrome, nonspecific cytotoxic cerebral edema is seen with swelling of astrocyte foot processes. The hallmark of hepatic encephalopathy is proliferation and enlargement of the so-called Alzheimer –Type astrocyte which is basically protoplasmic astrocytes. Longstanding heparin encephalopathy has been shown to be associated with degenervation changes in layer 5 and 6t of the cerebral cortex. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition, pp 792-794) 6. B, A, C, D, E These are some of the co-factors that have been shown to be helpful in the various metabolic disorders. (Batshaw M. Treatment of ureacycle disorders. Enzyme, 1987; Vol. 38/242. Fuhrman BP, et al. Pediatric Critical Care, 2nd Edition; pp 820-825) 7. C With adrenocortical insufficiency, hypotension is associated with low levels of stress hormones. Thus, hypoglycemia is more of a possibility than hyperglycemia. (DiAeage AM, Levine LS. Nelson’s Textbook of Pediatrics, 15th Edition; pp 1613-1617. Kaplan SA. Clinical Pediatric Endocrinology, 1990; pp 181-223) 8. C Diabetic ketoacidosis in the pediatric patient is a potentially life-threatening event. Ketosis and hyperglycemia result from an imbalance of glucagon and insulin levels with an increase in catecholamines, growth hormones and glucocorticoids. An increase in somatostatin is not associated with diabetic ketoacidosis, but it down regulates the production and release of glucagon and growth hormones. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1261-1270. Kaplan SA. Clinical Pediatric Endocrinology, 1990; pp 127-164) 9. B, A, D, C Diabetic ketoacidosis or any acute metabolic acidosis state will decrease PCO2 by 1.0 to 1.5 mmHg for each millimole change in bicarbonate concentration. In severe scoliosis, there is retraction of the chest wall causing chronic alveolar hypoventilation, with the development of chronic respiratory acidosis. A bicarbonate rise of 4 mmol will occur with a rise in 10 mmHg of PCO2. Here both pH and bicarbonate concentrations are higher than expected for the level of PCO2 elevation suggesting a mixed acid base disorder – metabolic acidosis superimposed or chronic respiratory acidosis. Botulism will cause rapid onset of respiratory failure causing pure respiratory acidosis. In acute respiratory acidosis, the pH will fall by approximately 0.08 unit for each 10 mmHg of PCO2. Plasma bicarbonate will increase 1 mmol/liter for each increase of 10 mmHg in PCO2. Salicylate intoxication causes acute metabolic acidosis. It also stimulates the respiratory center causing coincident respiratory alkalosis. A decrease in PCO2 is out of proportion to the fall in plasma bicarbonate which is suggestive of mixed acid-base disorder - metabolic acidosis and respiratory alkalosis. (Kaplan SA. Clinical Pediatric Endocrinology, 1990; pp 181-234. Rogers MC et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 351-363) 10. D The rapid ACTH stimulation test is only a screening test that should be verified by a more definitive test when the patient’s condition stabilizes. An abnormal response may be due to either primary or secondary adrenocortical insufficiency. A false negative result has been reported in patients with early ACTH deficiency. (Kaplan SA. Clinical Pediatric Endocrinology, 1990; pp 181-234. Furhman BP et al. Pediatric Critical Care, 2nd Edition; pp 826-843) 11. C Nearly all critically ill patients have decreased serum levels of T3 and 50% have a decrease in the level of T4 concentration with normal or low TSH. The reduction in T3 levels results from a decrease in deiodinase activity that occurs in critical illness. This is reflected in the increase in serum level of T3 that occurs during critical illness. This enzyme is responsible for the degradation reverse of T3, explaining the increase in serum levels of reverse T3 that occurs in critical illness. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1290-1297. Wilson D, et al. Serum free thyroxine values in term, premature and sick infants. J Ped, 1982; Vol 101, p 113)