e51CHAPTER 136 Board Review Questions Rationale Child A has hypovolemia due to gastroenteritis Child A has nor mal compensatory responses without evidence of end organ dys function Child B has an abno[.]
CHAPTER 136 Board Review Questions Rationale Child A has hypovolemia due to gastroenteritis Child A has normal compensatory responses without evidence of end-organ dysfunction Child B has an abnormal neurologic exam and a widening pulse pressure Child B is in compensated hypovolemic shock Compensated shock should be initially treated with rapid volume administration, whereas patients with hypovolemia can be safely treated with oral rehydration per WHO recommendations A 5-year-old child with acute lymphoblastic leukemia and neutropenia presents to the pediatric intensive care unit with evidence of septic shock Data suggest that children who receive ,40 mL/kg of intravenous fluids and are still in shock at the end of the first hour have worse outcomes than those who receive 40 mL/kg and are still in shock at the end of the first hour Therefore what is your goal? A Obtain a Scvo2 from the indwelling central catheter, place an arterial line and obtain a serum lactate, and then titrate fluid resuscitation until you see the Scvo2 and lactate improve to normal ranges B Treat with 20 mL/kg of crystalloid in #15 min, and then reevaluate for evidence of fluid response C Treat with 60 mL/kg of crystalloid fluid resuscitation within the first hour D Treat with 60 mL/kg of crystalloid and colloid as indicated within the first hour Preferred response: B Rationale Although data suggest that early, rapid fluid resuscitation improves mortality, there are accumulating data that suggest that fluid overload worsens mortality Therefore the goal in fluid resuscitation is to give just what the patient requires If the patient shows evidence of sustained response to fluid administration and resolution of shock, no further fluid boluses should be administered If the patient shows refractory shock, fluid resuscitation should be continued for up to a total of 60 mL/kg in the first hour After the first hour, if there is evidence of sustained shock, careful evaluation should be used to determine the indication for vasoactive/inotropic support with or without further fluid resuscitation You are working in the CICU and you receive a phone call from an outside provider in an emergency department caring for a 17-day-old newborn who weighs 3.2 kg and presented in shock The patient is a full-term infant born to a G2P2 female who did not receive prenatal care The patient was born at home and delivered by a midwife Delivery was uncomplicated The mother reports poor feeding for the last 24 hours, and this morning the newborn was found to be less responsive In the ED, the patient presents with the following vital signs: temperature, 36.7°C; heart rate, 185 beats per minute; blood pressure, 52/28 mm Hg; respiratory rate, 74 per minute The patient appears gray and is unresponsive What you recommend? A Ceftriaxone, 20 mL/kg intravenous bolus of crystalloid, and transfer to the PICU B Orotracheal intubation, ceftriaxone, 20 mL/kg intravenous bolus of crystalloid, and transfer to the PICU C Orotracheal intubation, ampicillin and gentamicin, 10 mL/kg intravenous bolus of crystalloid, continuous infusion of prostaglandin E1, and transfer to the PICU D Orotracheal intubation, ampicillin and gentamicin, 10 mL/kg intravenous bolus of crystalloid, echocardiogram, and transfer to the PICU Preferred response: C e51 Rationale Newborns (,28 days) presenting in shock should be suspected for sepsis and a ductal-dependent congenital heart disease Therefore fluid resuscitation should be provided, but it should start with a lower volume and then be reevaluated for responsiveness Ceftriaxone may be okay for newborns, but risks in the newborn period make ampicillin and gentamicin a better empiric choice Empirically starting a continuous infusion of prostaglandin E1 (PGE1) at 0.05 to 0.1 mg/kg/min may be lifesaving and should be started prior to obtaining the echocardiogram PGE1 may cause apnea, but in an unresponsive infant presenting in shock, early intubation is indicated You are caring for a 5-year-old female with acute viral myocarditis She is sedated, mechanically ventilated, and treated with a continuous infusion of epinephrine at mg/kg/min Her vital signs are as follows: temperature, 36.8°C; heart rate, 140 beats per min; blood pressure, 75/45 mm Hg; central venous pressure (CVP), 12 cm H2O Her serum lactate level is rising Echocardiogram shows that her right atrium is adequately filled, systolic ventricular function is depressed bilaterally with a left ventricular shortening fraction of 18% by M-mode The septum is midline The next best step in the management of this patient is to: A Call your extracorporeal life support team because she is failing medical management of heart failure B Deepen her sedation and start to cool her to reduce metabolic demand C Treat with a pulmonary vasodilator because you are concerned that her CVP suggests right ventricular failure D Treat with a vasodilator because you are concerned that her cardiac output is reduced to high systemic vascular resistance Preferred response: A Rationale Vasodilators may be indicated in a hypertensive patient with evidence of shock and low systolic function However, this patient is hypotensive, suggesting that peripheral vasodilation may not be indicated Although the patient’s CVP is greater than 10 cm H2O and the echo suggests low right ventricular systolic function, the septum remains midline, which suggests that reduction of pulmonary vascular resistance will not substantially increase cardiac output Although reduction of metabolic demand is a reasonable next step, deepening sedation carries the risk of worsening myocardial function Consideration of extracorporeal support is a reasonable next step in this patient with evidence of adequate right ventricular preload, low systolic function, and refractory shock despite high inotropic therapy Chapter 35: Pediatric Cardiopulmonary Bypass When blood comes into contact with the cardiopulmonary bypass circuitry, these foreign surfaces will not which of the following? A Activate inflammatory response B Cause hemolysis C Disrupt hemostasis D Shift the oxyhemoglobin curve leftward Preferred response: D Rationale It is well documented that nonendothelial blood contact activates the systemic inflammatory response and causes hemolysis and e52 S E C T I O N XV Pediatric Critical Care: Board Review Questions coagulopathy Oxyhemoglobin shifts are caused by changes in blood pH, temperature, pco2, and 2,3-DPG Which of the following is an effective strategy to protect the immature myocardium during ischemic arrest? A Increase the cardiac membrane resting potential B Keep the myocardium warm C Perfuse the coronaries with a hypotonic solution D Prevent intracellular calcium accumulation Preferred response: D Rationale Calcium shifting at the cellular membrane is an energy-dependent process, and minimizing intracellular calcium accumulation will help to prevent ATP depletion Decreasing the cardiac membrane resting potential to achieve diastolic arrest is the goal of depolarizing cardioplegia Delivering a cold cardioplegia solution will minimize metabolic demands and prolong the myocardial tolerance to ischemia An isotonic or hypertonic cardioplegia solution is desired to reduce intracellular water accumulation and edema During the aortic cross clamp, which of the following perfusion techniques would be the most effective in reducing collateral blood flow to the heart and improving operative visibility? A Administer more heparin and raise the activated coagulation time (ACT) B Decrease arterial flow and patient temperature C Increase the mean arterial pressure and cardiac index D Transfuse an isotonic crystalloid solution and reduce viscosity Preferred response: B Rationale Patients with pulmonary blood flow restrictions (e.g., tetralogy of Fallot, pulmonary atresia) can develop major aortopulmonary collateral arteries, and these collaterals can flood the heart during the aortic cross-clamp period if cardiopulmonary bypass flow is maintained This excessive blood return not only obscures the surgical site but may also warm the cold arrested myocardium or wash out cardioplegia from the coronary arteries Hypothermia and perfusion flow rate reduction can attenuate this collateral flow while maintaining adequate oxygenation delivery to the patient Which of the following factors does not increase the incidence of acute kidney injury (AKI) during cardiopulmonary bypass? A Deep hypothermic circulatory arrest (DHCA) B Hypotension C Pulsatile perfusion flow D Younger age Preferred response: C Rationale The kidneys perceive nonpulsatile flow or a decrease in arterial flow as hypovolemia, and the resultant neurohormonal cascade is thought to trigger the AKI complex Since most perioperative risk factors such as younger age and the incidence of higher surgical complexity are nonmodifiable, therapeutic strategies have focused on optimally managing perfusion flow rate, arterial pressure, and hematocrit Chapter 36: Critical Care After Surgery for Congenital Cardiac Disease A 10-month-old girl (8 kg) is recovering from surgery to repair a ventricular septal defect She has been taking her usual diet of breast milk and age-appropriate food since postoperative day On postoperative day 3, while extubated and still requiring oxygen via nasal cannula, a chest radiograph showed a moderately sized right pleural effusion A pigtail catheter was placed in the right pleural space and yielded 150 ml of white effluent containing 2000 WBCs (95% lymphocytes) and elevated triglycerides (410 mg/dL) The pleural catheter drains another 100 ml over the following day and follow up chest radiograph obtained on postoperative day shows a small residual effusion The MOST appropriate next step in the management of this patient is to: A Begin a diet with medium-chain triglycerides (MCT) as the source of fat B Begin an intravenous infusion of octreotide C Continue current management and follow chest tube output D Discontinue enteral nutrition and begin total parenteral nutrition E Perform a lymphangiogram in preparation for lymphatic embolization or thoracic duct ligation Preferred response: A Rationale This patient developed chylothorax following cardiac surgery With drainage of 12.5 mL/kg over 24 hours, this chylothorax would be classified in the “low volume” category The initial management of low volume chylothoraces is centered on a diet low in long-chain triglycerides, where the source of fat is in the form of medium-chain triglycerides (MCT) This is often sufficient to resolve the chylothorax within days If persistent, additional treatments may be started sequentially; these include enteral fasting with total parenteral nutrition, octreotide, and thoracic duct embolization or surgical ligation A 5-day-old child born with d-transposition of the great arteries is recovering in the cardiac ICU following an arterial switch operation Approximately twelve hours after successful separation from cardiopulmonary bypass, the patient is noted to have frequent premature ventricular contractions (PVCs) She is receiving mechanical ventilation and an infusion of epinephrine (0.05 mg/kg/min) The vital signs are heart rate, 170 beats per minute; respiratory rate, 28 per minute; blood pressure 55/30 mm Hg (mean 41 mm Hg), central venous pressure, 14 mm Hg; left atrial pressure, 17 mm Hg Electrolytes are normal, but an arterial blood gas shows a mild metabolic acidosis (7.34/38/123/-3/99%) and a lactate of 3.2 mmol/L The MOST appropriate next step in the management of this patient is to: A Administer a 10 mL/kg intravenous bolus of 5% albumin B Obtain a STAT chest radiograph C Obtain a STAT echocardiogram D Start a furosemide infusion at 0.1 mg/kg/h E Start a vasopressin infusion at 0.3 mU/kg/min Preferred response: C CHAPTER 136 Board Review Questions Rationale This patient is tachycardic, hypotensive, has a disproportionate elevation of the left atrial pressure, an elevated blood lactate, and new onset of frequent ventricular ectopy Although it would be tempting to ascribe these findings to the vagaries of a post-cardiopulmonary bypass low cardiac output state, they are much more likely to be the manifestation of poor coronary blood flow Therefore, it is imperative that a surgical issue, such as a coronary reimplantation kink or tamponade be ruled out A STAT echocardiogram should be obtained to evaluate function, rule out tamponade, and ascertain adequate coronary blood flow If the coronary buttons cannot be well visualized by echocardiogram, emergent cardiac catheterization should be performed A fluid bolus would not be indicated in this patent with an already elevated left atrial pressure Although a furosemide infusion is often initiated in the postoperative period, it would not address the primary concern of myocardial ischemia Vasopressin would cause an increase in systemic vascular resistance, but it would not be a fruitful therapy if the patient indeed has a kink of the left coronary button A chest radiograph would have been useful to rule out a new pulmonary process or pleural effusions, but would be low yield in this situation A 6-day-old child is returned to the cardiac intensive care unit after a stage I palliation (Norwood procedure) for hypoplastic left heart syndrome He remains endotracheally intubated and has an open sternum Heart rate is 180 beats/min and blood pressure is 55/28 mm Hg while on epinephrine (0.05 µg/kg/ min) and milrinone (0.5 µg/kg/min) He is being ventilated with a tidal volume of mL/kg, PEEP of cm H2O, rate of 26 breaths/min, and Fio2 of 0.4 An arterial blood gas analysis shows severe metabolic acidosis (pH 7.16, Paco2 40 mm Hg, Pao2 78 mm Hg, Sao2 94%, base deficit, 13) What is the next best step to manage this condition? A Decrease the Fio2 to 0.21 B Decrease the milrinone dose to 0.3 µg/kg/min C Increase the epinephrine dose to 0.08 µg/kg/min D Increase the respiratory rate to 30 breaths/min Preferred response: A Rationale The patient has classic signs of an unbalanced circulation following the Norwood procedure, with excess pulmonary blood flow and decreased systemic perfusion (high Qp:Qs) This is a serious emergency and requires prompt action Decreasing the Fio2 to room air can be accomplished rapidly and will help balance the Qp:Qs In some cases, carbon dioxide may need to be added to the inspired gas or subatmospheric Fio2 to help reduce excessive pulmonary blood flow Decreasing the dose of milrinone would not be a reasonable strategy for this patient, who can in fact benefit from additional afterload reduction to increase systemic blood flow and help balance the Qp:Qs For the same reason, increasing the dose of epinephrine could be detrimental as it will likely increase the systemic vascular resistance and increase pulmonary blood flow Increasing the respiratory rate to 30 breaths/ would lower the Paco2, and although this will help compensate the acidosis, it will also lower pulmonary vascular resistance and adversely contribute to the already increased pulmonary blood flow e53 A 6-month-old child with history of tricuspid atresia returns to the cardiac intensive care unit intubated following a bidirectional Glenn anastomosis She is hemodynamically stable and in sinus rhythm but has significant hypoxemia (Sao2 of 65%) despite being offered a Fio2 of 1.0 through the ventilator The hypoxemia persists despite adequate sedation and intravascular volume expansion with packed red blood cells to increase the hematocrit to 40% Of the following, which intervention is least likely to meaningfully improve the arterial oxygen saturation in this patient? A Controlled hypoventilation (permissive hypercapnia) B Head elevation (30 degrees) C Inhaled nitric oxide D Intravenous milrinone and epinephrine Preferred response: C Rationale Following the bidirectional Glenn anastomosis, arterial oxygen saturation should be in the 80% to 85% range; however, stabilization to this level can take a number of days Persistent hypoxemia (Sao2 ,70%) can be secondary to a low cardiac output state (low Svo2), low pulmonary blood flow, or lung disease Treatment is directed at improving contractility, increasing superior vena cava venous return, reducing afterload, and ensuring the patient has a normal rhythm and hematocrit Increased pulmonary vascular resistance is an uncommon cause, and inhaled nitric oxide (NO) is not generally beneficial in these patients This finding is not surprising because pulmonary artery (PA) pressure and resistance and vascular tone are not high enough following this surgery to see a demonstrable benefit from NO Controlled hypoventilation targeting hypercapnia promotes increased cerebral blood flow and, consequently, increased blood flow through the superior vena cava (SVC)-PA anastomosis Persistent profound hypoxemia should be investigated in the catheterization laboratory to evaluate hemodynamics, look for residual anatomic defects limiting pulmonary flow, such as SVC or PA stenosis or a restrictive atrial septal defect (ASD), and coil any significant venous decompressing collaterals (e.g., azygous vein), if present Following a Fontan operation for palliation of the hypoplastic left heart syndrome, which of the following postoperative strategies is commonly used? A Early extubation whenever the patient is able to assume spontaneous breathing B Forced diuresis to lower the central venous pressure C High doses of dopamine and epinephrine to increase systemic vascular resistance and blood pressure D Mechanical ventilation with high levels of positive end- expiratory pressure to optimize lung inflation and increase pulmonary blood flow Preferred response: A Rationale Following a Fontan operation, liberation from positive pressure ventilation should be accomplished as soon as the patient is able to assume spontaneous breathing, provided there is no significant lung disease or atelectasis For this reason, prolonged sedation and paralysis generally are not indicated High doses of vasoactive drugs should be avoided because they increase the afterload to the systemic right ventricle Lowering the central venous pressure is not indicated because pulmonary blood flow is largely dependent e54 S E C T I O N XV Pediatric Critical Care: Board Review Questions on systemic venous return A high level of positive end-expiratory pressure should be avoided in these patients because it increases intrathoracic pressure, reduces venous return, and consequently reduces pulmonary blood flow Which of the following is true for a patient with tetralogy of Fallot? A A residual ventricular septal defect (VSD) promotes left-toright shunt and augments pulmonary blood flow B Epinephrine is the drug of choice in the postoperative period because it increases cardiac output and contractility of the poorly compliant right ventricle C Patients usually require high right atrial pressure postoperatively because of the hypertrophic and poorly compliant right ventricle D The presence of an atrial level communication is undesirable because it can lead to hypoxemia and decreased preload to the left ventricle Preferred response: C Rationale The poorly compliant right ventricle requires high right-sided filling pressures (right atrial pressure) Use of vasodilators should be avoided during a hypercyanotic spell, because lowering systemic vascular resistance will increase the right-to-left shunt and worsen hypoxemia and acidosis An atrial level communication is highly desirable in patients with significant right ventricular diastolic dysfunction, because it allows for a right-to-left atrial level shunt that ensures adequate left ventricular preload (although it causes arterial oxygen desaturation) Milrinone is the drug of choice in the postoperative period because of its lusitropic effects A residual ventricular septal defect (VSD) is deleterious, particularly in the setting of a persistent right ventricular outflow tract obstruction Chapter 37: Cardiac Transplantation A 5-year-old patient with dilated cardiomyopathy presents to the cardiac ICU with severe decompensated congestive heart failure Which one of the following therapeutic options would be the most successful bridge to transplant? A Enalapril B Extracorporeal membrane oxygenation (ECMO) C Furosemide D Mechanical ventilation E Ventricular assist device Preferred response: E Rationale While all options could be used to treat congestive heart failure, use of a ventricular assist device has been shown to improve waitlist mortality and improve posttransplant outcomes Mechanical ventilator support and ECMO are risk factors for increased waitlist and posttransplant mortality Which of the following would be the strongest contraindication to isolated heart transplantation in a neonate? A Common pulmonary vein atresia B Dextrocardia C Discontinuous pulmonary arteries D Double aortic arch E Total anomalous pulmonary venous return Preferred response: A Rationale Isolated heart transplantation in the presence of pulmonary vein atresia would be technically difficult to perform, especially in a neonate All other conditions presented could be overcome with good surgical planning In a 2-month-old infant with hypoplastic left heart syndrome who has undergone a Stage I reconstruction, the strongest indication for heart transplantation would be which of the following: A Aortic arch obstruction with right ventricular dysfunction B Marked cyanosis C Protein losing enteropathy D Restrictive atrial septal defect E Severe tricuspid valve regurgitation Preferred response: E Rationale Significant tricuspid valve regurgitation is a risk factor for failure of single ventricle palliation with poor outcomes Aortic arch obstruction and restrictive atrial septal defect require intervention Should that be unsuccessful, then transplantation could be considered Protein losing enteropathy is generally not a complication of a stage I reconstruction, and cyanosis alone is not an indication for transplantation You admit a 12-year-old from the operating room following heart transplantation The nurse is concerned about an episode of hypotension and asks which value on the monitor most likely indicates the presence of ventricular diastolic dysfunction You answer that it is which of the following: A Cardiac index 3.3 L/min/m2 B CVP 22 mm Hg C Heart rate 115 bpm D NIRS 65% E PA pressure 32/15 mm Hg Preferred response: B Rationale Diastolic dysfunction of the right ventricle is common after heart transplantation Central venous pressure (CVP) represents the end-diastolic pressure of the right ventricle in the setting of normal tricuspid valve function Therefore, elevation of the CVP postcardiac surgery indicates the presence of ventricular diastolic dysfunction The other parameters listed have values that are normal or near normal following heart transplantation The major cause of death in adolescents after heart transplant is which of the following? A Dysrhythmia B Noncompliance C Renal failure D Thromboembolism Preferred response: B Rationale Currently the major cause of death in the adolescent heart transplant recipient is noncompliance with the medical regimen CHAPTER 136 Board Review Questions e55 The preferred anticoagulant for patients in the intensive care unit who have myocardial dysfunction and are awaiting a heart transplant is which of the following? A Aspirin B Coumadin C Heparin D Lovenox Preferred response: C the transplanted heart reflect a significant shift to the left of the pressure/volume curve Diastolic dysfunction can be demonstrated from the early transplant period Diastolic dysfunction is a significant impairment to early allograft function, limiting cardiac output Diastolic dysfunction emphasizes the importance of heart rate and early sinus node function The capability of temporary pacing in the early perioperative period is mandatory Rationale Increased perioperative mortality for heart transplantation is associated with which of the following? A Mitral valve insufficiency B Tricuspid valve insufficiency C Pulmonary arterial pressure ,15 mm Hg D Pulmonary vascular resistance (PVR) Wood units Preferred response: D All patients waiting for heart transplantation should be managed with systemic anticoagulation Heparin is preferred, but warfarin is acceptable in a stable patient who is receiving inotropic support We add a word of caution regarding the use of low-molecularweight heparin for prophylaxis: Enoxaparin cannot be easily reversed in a patient who must go to the operating room emergently because a donor heart has been identified Cardiovascular surgeons prefer using heparin for prophylactic anticoagulation First-line medication for management of hypotension in the potential heart donor is which of the following? A Dobutamine B Dopamine C Epinephrine D Vasopressin Preferred response: D Rationale A catecholamine surge causing unnatural circulatory physiology that rapidly evolves is associated with brain death, making management of the donor difficult This intense sympathomimetic outflow initially causes vasoconstriction resulting in tachycardia, hypertension, and increased myocardial oxygen demand The result can be a direct injury to the myocardium in the potentially transplantable heart Myocardial structural damage that includes myocytolysis, contraction band necrosis, subendocardial hemorrhage, edema formation, and interstitial mononuclear infiltration is seen This initial sympathetic outflow is followed by a loss of sympathetic tone, resulting in marked vasodilation and hypotension The hypotension and cardiovascular collapse are related to decreased systemic vascular resistance rather than primary myocardial dysfunction Vasopressin is now the first-line blood pressure support medication because it treats diabetes insipidus in addition to supporting blood pressure Vasopressin infusion of less than 2.5 units/hour usually is sufficient to increase mean arterial blood pressure and not cause end-organ injury Cardiac output in the heart immediately after transplantation is impaired primarily by which of the following? A Arch obstruction B Diastolic dysfunction C Mitral valve insufficiency D Tricuspid valve insufficiency Preferred response: B Rationale The major changes in the physiology of the transplanted heart are related to autonomic denervation, including diastolic dysfunction and an exaggerated response to exogenously administered catecholamines The transplanted heart also must adapt to a new environment related to the recipient’s lung function and elevated pulmonary vascular resistance (PVR) Hemodynamics of Rationale High PVR in the recipient increases perioperative morbidity and mortality and can affect late survival All potential heart recipients undergo cardiac catheterization prior to heart transplantation to document the anatomy of systemic and pulmonary venous connections, determine pulmonary artery size and distribution, and calculate PVR The upper limit of PVR associated with successful orthotopic heart transplantation is not known Criteria developed from the adult heart transplant experience indicate that a PVR greater than Wood units or a transpulmonary gradient (pulmonary artery mean pressure – left atrial mean pressure) greater than 15 mm Hg is associated with increased perioperative mortality The transpulmonary gradient is the most useful number for estimating PVR because measurement of cardiac output in the catheterization laboratory can be flawed In children the PVR index, which is determined by dividing transpulmonary gradient by cardiac index, is more useful because children come in all sizes A PVR index less than index units is associated with low perioperative mortality 10 Hyperglycemia following heart transplantation is most likely related to which of the following? A Antithymocyte globulin B Basiliximab C Furosemide D Tacrolimus Preferred response: D Rationale Hyperglycemia is common after heart transplantation with tacrolimus-based immune suppression The combination of decreased insulin production from islet cells caused by tacrolimus and decreased peripheral utilization related to high-dose corticosteroids results in nonketotic hyperglycemia Insulin is initially mandatory in management but often can be discontinued if the tacrolimus dose is reduced and the corticosteroid portion of maintenance immune suppression is discontinued 11 Diastolic dysfunction in a patient after heart transplantation most commonly will manifest as which of the following changes following a normal saline solution fluid challenge? A An increase in right atrial pressure by mm Hg B An increase in left atrial pressure by mm Hg C No change in right atrial pressure D No change in stroke volume Preferred response: B ... duct ligation Preferred response: A Rationale This patient developed chylothorax following cardiac surgery With drainage of 12.5 mL/kg over 24 hours, this chylothorax would be classified in the... the source of fat is in the form of medium-chain triglycerides (MCT) This is often sufficient to resolve the chylothorax within days If persistent, additional treatments may be started sequentially;... beneficial in these patients This finding is not surprising because pulmonary artery (PA) pressure and resistance and vascular tone are not high enough following this surgery to see a demonstrable