# Pediatric Critical Care Review Hasan Pappas

1. All of the following statements regarding pain neurophysiology are true except: A. A-d fibers are associated with sharp localized pain, whereas C fibers are associated with dull diffuse pain B. Substance P, a peripheral pain transmitter can increase the responsiveness of peripheral nociceptors to pain C. The underlying principle of transcutaneous electrical nerve stimulation (TENS) is such that large diameter peripheral nerves are stimulated, effectively blocking nociceptive information from the periphery D. The neuroanatomic pathways for pain transmission develop at 4 months of age E. Pain may be relieved by altering the patient’s emotional responses to it Click here for answer 2. Which of the following statements is true regarding opioids and opioid receptors: A. The opioids most commonly used in the management of pain are kappa agonists B. The receptor m1 involves respiratory depression and the m2 receptor involves supraspinal analgesia C. m2 receptor stimulation causes tachycardia D. The m2 receptors are more abundant at birth and may account for the increased risk of opioid-induced respiratory depression in infants Click here for answer 3. Match the pain receptor with its anticipated effect or prototype agonist: A. m receptor B. k receptor C. d receptor D. s receptor ____ 1. Dysphoria/hallucinations ____ 2. Inhibition of antidiuretic hormone release ____ 3. Inhibits GI motility ____ 4. Phencyclidine ____ 5. Methadone Click here for answer 4. Match the opioid receptor with its effect: A. Seizures in the newborn B. Catastrophic interaction with MAO inhibitors C. Chest wall and glottic rigidity Click here for answer 5. Which of the following statements is true regarding the commonly used m-agonist drugs: A. Meperidine produces tachycardia B. Morphine causes histamine release C. Fentanyl minimizes hemodynamic effects D. Codeine can only be administered orally E. All of the above Click here for answer 6. Which of the following statements is true regarding fentanyl: A. Fentanyl is less potent than morphine B. Fentanyl is largely devoid of hypnotic and sedative activity C. Sufentanil is less potent than fentanyl D. Fentanyl binds weakly to the plasma protein a-1 acid glycoprotein Click here for answer 7. Which of the following statements is true regarding meperidine: A. Is 10 times more potent than morphine B. Effectively stops shivering at low doses C. The metabolite normeperidine prevents central nervous system excitation D. May be used safely in combination with MAO inhibitors Click here for answer 8. Which of the following statements is true regarding methadone: A. The half life is approximately 19 hours B. Clonidine may be used concomitantly to treat opiate withdrawal C. It has excellent gastrointestinal tract bio-availability D. All of the above Click here for answer 9. Which of the following is true regarding hydromorphone: A. Rapid onset with 4-6 hour duration B. More potent than morphine C. Less sedating than morphine D. All of the above Click here for answer 10. Which of the following is/are true regarding intrathecal and epidural opioid analgesia: A. Morphine will have a greater latency and duration of action than fentanyl B. Hydrophilic agents produce more segmental analgesia with less rostral spread than lipid-soluble agents C. Both light touch and proprioception are preserved D. All of the above Click here for answer 11. All of the following statements are true regarding naloxone except: A. It is an opioid antagonist B. Very small doses may alleviate the respiratory depression effect of opioids without affecting their analgesic effects C. It is rapidly metabolized in the liver D. Produces sedation in patients who have not received opioids E. May induce withdrawal symptoms in chronic opioid abusers Click here for answer 12. All of the following statements regarding ketamine are true except: A. Loss of consciousness is heralded by nystagmus B. Nightmares are more common in children than adults C. Cerebral metabolism and cerebral blood flow increase D. Mean arterial pressure, heart rate and cardiac output increase E. Profound hypotension may occur in patients with depleted catecholamine stores Click here for answer 13. Select whether the following statements are true or false regarding ketamine: ____ It is a ventilatory depressant ____ Laryngeal reflexes are generally lost ____ Increases pulmonary compliance ____ Highly lipid soluble ____ Redistribution explains its short duration of action ____ Reduction in liver blood flow prolongs half life Click here for answer 14. Which of the following statements is/are true regarding local anesthetics: A. There are two types – amides and esters, which are both weak bases B. The non-ionized (base) form crosses the nerve membrane C. Acidosis and hypercapnea increase their toxicity D. Because of the lower Cm (minimum concentration necessary to block a nerve impulse), less local anesthetic is necessary to block pain than produce paralysis E. All of the above Click here for answer 15. Rank the following in order from highest to lowest regarding absorption of anesthetic administration—1=highest, 5=lowest: ____ Distal peripheral ____ Caudal/epidural ____ Brachial plexus ____ Subcutaneous ____ Intercostal/intratracheal Click here for answer 16. All of the following regarding benzodiazepines are true except: A. GABA is the major neuro-inhibitory neuro-transmitter within the brain B. Binding to a sites facilitates binding to b sites which causes hyperpolarization C. Tidal volume is decreased D. Produces preload and afterload reduction E. Midazolam increases coronary sinus blood flow and myocardial oxygen consumption Click here for answer 17. Benzodiazepines can effectively treat anxiety in children. Select whether the following statements are true or false: ____ Midazolam is 4 times more potent than diazepam ____ Midazolam is painful when administered intravenously ____ When midazolam is used > 7 days and acutely stopped, withdrawal symptoms may be present Click here for answer 18. Match the following barbiturate with its associated effect: A. Pentobarbital B. Thiopental ____ 1. Effect terminated by redistribution from the brain to other body compartments ____ 2. Sleep induced in 10-15 minutes Click here for answer 19. Select whether the following statement is true or false: ____ The incident rate of cardiac arrest with anesthesia in children is 1:700 Click here for answer 20. Match the American Society of Anesthesiology physical status classification with the appropriate descriptor: A. Class I B. Class II C. Class III D. Class IV E. Class V ____ 1. Moribund patient with little chance of survival ____ 2. Severe systemic disease ____ 3. No organic, physiologic, biochemical, or psychiatric disturbance ____ 4. Mild-moderate systemic disturbance ____ 5. Severe systemic disorder which is life-threatening and not always correctable by the operative procedure Click here for answer 21. Which of the following drugs stimulate histamine release: A. Morphine B. Protamine C. Barbiturates D. Latex E. All of the above Click here for answer 22. Select whether the following statements are true or false regarding inhalational anesthetics: ____ Most common pediatric inhalational anesthesia involves halothane, enflurane and isoflurane usually in conjunction with and oxygen/nitrous oxide mixture ____ Minute ventilation and inspired concentration determine rate of removal of the agent from the alveolus ____ Nitrous oxide achieves steady state within 5-10 minutes Click here for answer 23. All of the following statements regarding succinylcholine are true except: A. Intragastric, intraocular, and intracranial pressure are increased B. Metabolism is by plasma and hepatic pseudocholinesterase C. Hepatic dysfunction, hypermagnesemia, and pregnancy prolong emergence D. Severe bradycardia may occur E. A decrease in potassium accompanies administration Click here for answer 24. Which of the following statements is/are true regarding non-depolarizing neuromuscular blockers: A. They represent false neurotransmitters B. Residual effects can be characterized by an unsustained response to a tetanic stimulation of 50Hz at 2.5 seconds. C. Hypokalemia, respiratory acidosis, hypermagnesemia, and a decreased body temperature can result in failure to reverse their effects. D. Calcium channel blockers, nitroglycerin and high dose corticosteroids potentiate their neuromuscular blockade E. All of the above Click here for answer Answers 1. D Neuroanatomic pathways are present at birth they do not develop at 4 months of age. All of the other statements are correct. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1548-1550) 2. D The m receptor agonists are the most commonly used opioids for analgesia. The m1 receptor is the subtype that provides supraspinal analgesia. The m2 receptor produces respiratory depression, inhibition of gastrointestinal motility, and spinal analgesia. Furthermore, the m2 receptors cause bradycardia and sedation. Newborns may be sensitive to an age-related receptor phenomenon that leads to opiate induced respiratory depression. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1552-1554) 3. D, B, A, D, A The m2 receptor inhibits gastrointestinal motility. Methadone, morphine, fentanyl and meperidine are agonists for the m receptor. The k receptor inhibits antidiuretic hormone release. The d receptor produces analgesia, respiratory depression, euphoria and physical dependence. The psychotomimetic effects that are observed with some opiates including dysphoria and hallucinations are associated with the s receptor. Phencyclidine is an agonist for the s receptor. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1552-1554; Tables 46.2 and 46.3) 4. B, C, A Neonatal seizures can occur with the use of morphine at commonly prescribed doses. Meperidine is also associated with seizure activity. This, however, can occur in any age group and is related to the buildup of the toxic metabolite normeperidine. The serotonin syndrome occurs following the use of serotomimetic agents of which meperidine is included. When used alone or in combination with monoamine oxidase inhibitors a symptom complex characterized by myoclonus, rigidity, hyperreflexia, shivering, confusion, agitation, restlessness, coma, autonomic instability, low-grade fever, nausea, diarrhea, diaphoresis, flushing, and rarely, rhabdomyolysis and death can occur. The development of chest wall rigidity is a side effect associated with the rapid administration of fentanyl. This effect can be treated with the administration of either a neuromuscular blocker or naloxone. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1554-1559; Bodner RA, et al. Neurology 1995; 45:219-23) 5. E All of the statements regarding the m receptor agonist drugs are true. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1552-1560) 6. B Fentanyl is approximately 100 times more potent than morphine and is largely devoid of hypnotic or sedative activity. Sufentanyl is approximately 10 times more potent than fentanyl. Alfentanil is approximately 10 times less potent than fentanyl. The a-1 acid glycoprotein is an acute phase protein that inhibits platelet aggregation, and phagocytosis, and may help to regulate collagen fiber formation in healing. Fentanyl is tightly bound to alpha-1 glycoprotein. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1557-1558; Fuhrman BP, Pediatric Critical Care, 2nd Edition; p 807; Wilson AS, et al. Anesth Analg 1997; 84: 315-8) 7. B Meperidine is 10 times less potent than morphine. It is unique among the opioids in its ability to stop shivering from amphotericin, blood products, anesthetics and hypothermia. The metabolite normeperidine causes central nervous system excitation and seizures. See response to Question 4 regarding the interaction of meperidine and MAO inhibitors. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1558-1559; Bodner RA, et al. Neurology 1995; 45:219-23) 8. D Methadone has a half-life of approximately 19 hours. Clonidine is useful as an adjunct to treat opioid withdrawal. The bioavailability of methadone from the gastrointestinal tract is excellent. It is estimated at 80-90%. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1559) 9. D Hydromorphone has a rapid onset of action with a 4-6 hour duration. It is 6-7 times more potent than morphine and 10 times more lipid soluble. Its half-life is 3-4 hours. Hydromorphone is far less sedating than morphine and associated with fewer systemic side effects. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 1559) 10. D Lipid solubility affects the transition of opioid analgesics from the aqueous side of the cerebrospinal fluid to the lipid phase of the underlying neuraxis where the receptors are located. Hydrophilic agents like morphine have a greater latency and duration of action than the more lipid soluble agent fentanyl. However, the lipid soluble agents produce more segmental analgesia associated with less rostral spread than the less lipid soluble agonists. Spinal opiates produce analgesia without altering autonomic or neuromuscular function. In addition, both light touch and proprioception are preserved. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1561-1562) 11. D Naloxone is a non-selective, opioid antagonist that works in small doses to alleviate the respiratory depression associated with opioids without affecting the analgesic properties. It is rapidly metabolized in the liver. Naloxone has no effect on the mental status of patients who have not received opioids. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1562-1563) 12. B Vertical or horizontal nystagmus heralds the onset of the loss of consciousness after ketamine administration. Ketamine is an excitatory hallucinogen that produces a coupled increase in both cerebral metabolism and blood flow. This has the effect of raising intracranial pressure. Ketamine also increases mean arterial blood pressure, heart rate and cardiac output through an increase in plasma catecholamine levels. If a patient is catecholamine deficient, profound hypotension or death may occur. Nightmares occur as a side effect in about 10% of adult patients and 5% of pediatric patients. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1563-1564) 13. T, F, T, T, T, T Ketamine is a ventilatory depressant that reduces the ventilatory response to carbon dioxide. Laryngeal reflexes remain intact but this does not preclude the potential for aspiration. Ketamine increases pulmonary compliance by direct action on bronchial smooth muscle and indirectly by increasing plasma catecholamine levels. The drug is highly lipid soluble. Its redistribution rather than biotransformation or elimination is responsible for its short half-life. Reduction in liver blood flow leads to a prolongation of the serum half-life of ketamine. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1563-1564) 14. E The local anesthetics are of two types, amides and esters, which are both weak bases that block nerve conduction at the sodium channel when they are in their ionized form. In order to gain access to the channel, the drug must cross the membrane. It does this in its ionized form. The minimum concentration (Cm) of a local anesthetic is the concentration necessary to block nerve impulse conduction. Unmyelinated nerve fibers carry nociceptive information and have a lower Cm than heavily myelinated fibers. Less local anesthetic is necessary to block the transmission of pain than is necessary to produce muscle paralysis. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1565-1567) 15. 4, 2, 3, 5, 1 The absorption of local anesthetic is dependent on the site of the block. The order of absorption from highest to lowest is intercostal, intrathecal, > caudal/epidural > brachial plexus > distal peripheral > subcutaneous. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 1566) 16. E GABA is the major inhibitory neurotransmitter in the brain. Glycine is an inhibitory neurotransmitter in the spinal cord and brainstem. The GABA receptor has two alpha and two beta subunits. Binding of benzodiazepines to the alpha subunits of the GABA receptor facilitates binding to the beta-receptors and promotes membrane hyperpolarization and resistance to neuronal excitation. The benzodiazepines can blunt or abolish the respiratory responses to hypercarbia and hypoxia. They produce hypoventilation by reducing tidal volume. The benzodiazepines produce minimal cardiac affects. However, they do reduce preload and afterload. They increase, rather than decrease coronary sinus blood flow and myocardial oxygen consumption. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1573-1574) 17. T, F, T Midazolam is 4 times more potent than diazepam and can be painlessly administered. When used for continuous sedation, usually for more than a week, dependence and withdrawal may occur when the drug is stopped. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1574-1576) 18. B, A Recovery from the effects of thiopental and methohexital are a result of drug redistribution and not biotransformation or elimination. Pentobarbital is used to induce sleep. It acts within 10-15 minutes of an intravenous or intramuscular injection and lasts approximately 2-6 hours. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 1576) 19. T The incidence of cardiac arrest associated with anesthesia is 1:600 for infants, 1:700 for children, and 1:2500 for adults, respectively. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 1577) 20. E, C, A, B, D The preoperative assessment of surgical risk or postoperative complications has been classified according to the American Society of Anesthesiologists. The classification ranges from Class 1 to Class 5. As the patient’s physiologic dysfunction worsens; a higher Class is attained. This higher Class has an increased risk of anesthetic related complications and death. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p 1577; Table 46.12) 21. E All of the agents listed stimulate histamine release. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; p1577) 22. T, F, T The inhalational agents mentioned are commonly used in pediatric anesthesia. The rate of delivery of the agent to the alveolus is the function of minute ventilation and inspired concentration, but the rate of removal is dependent upon cardiac output and the solubility of the agent. Nitrous oxide is relatively insoluble and can achieve steady state within 5-10 minutes. Halothane requires 15-20 minutes to achieve steady state. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1579-1583) 23. E Hyperkalemia is associated with the administration of succinylcholine not hypokalemia. All of the other statements are true regarding succinylcholine. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1584-1585) 24. E All of the statements regarding non-depolarizing neuromuscular blockers are true. (Rogers MC, et al. Textbook of Pediatric Intensive Care, 3rd Edition; pp 1584-1587)