Lippincott's Anesthesia Review: 1001 Questions and Answers
Chapter 19. Critical Care
David Stahl, Daniel Johnson, and Edward Bittner
1. A 78-year-old otherwise-healthy woman arrives in the postanesthesia care unit after an urgent cystoscopy and ureteral stent placement for an impacted ureteral stone. In the operating room, there were no complications and only minimal blood loss. One hour later, she is febrile to 102.3°F, tachycardic with a heart rate of 117 bpm, and hypotensive with a noninvasive blood pressure of 73/42 mm Hg. Blood cultures are drawn and broad-spectrum antibiotics are initiated. A central venous catheter is placed, and the central venous pressure is measured at 2 mm Hg. The best next step in the management of her shock is
A. Start dobutamine for increased inotropy
B. Fluid resuscitation to restore adequate preload
C. Blood transfusion to a goal hemoglobin concentration of 12 g/dL
D. Initiate nitroglycerin infusion to off-load the right ventricle
2. Shock is most accurately defined as
A. Inadequate tissue perfusion to meet the oxygen demand of end organs
B. Hypotension not responsive to intravenous fluid administration
C. An irreversible process of multisystem organ failure
D. Decreased blood flow resulting from inadequate cardiac output
3. A 73-year-old man with a history of chronic obstructive pulmonary disease (COPD) on home oxygen was initially admitted to the medical floor for a COPD exacerbation. Over the past few hours, he has developed altered mental status and hypotension. He is transferred to the ICU, intubated, and vasopressors are started to support his blood pressure. A pulmonary artery catheter is placed via the right internal jugular vein. Initial readings reveal central venous pressure = 23 mm Hg, positive airway pressure = 34/15 mm Hg, pulmonary capillary wedge pressure = 4 mm Hg, and CO = 1.9 L/min. The most likely diagnosis is
A. Hypovolemic shock from inadequate fluid resuscitation
B. Septic shock from pneumonia
C. Anaphylactic shock from medications given during intubation
D. Cardiogenic shock from right-ventricular failure
4. A 54-year-old man is postoperative day 1 after a pancreaticoduodenectomy for pancreatic cancer, complicated by a small intraoperative bile leak. He is febrile to 39.5°C, rigorous, and hypotensive with a blood pressure of 71/32 mm Hg. He is admitted to the ICU. Laboratory work reveals a leukocytosis with bandemia. Despite 4 L of intravenous crystalloid, he remains hypotensive. The most accurate diagnosis for his condition is
A. Postoperative infection
C. Severe sepsis
D. Septic shock
5. Dopamine acts on all of the following receptors, except
6. All of the following may be caused by β-agonist effects of vasopressors, except
A. Increased inotropy
C. Inhibition of renin secretion
D. Uterine relaxation
7. You are called to the ER to assist in the intubation and management of a 26-year-old man who sustained significant closed head injury during a motorcycle collision. Following uneventful intubation, you accompany the patient and neurosurgery team to the CT scanner where you see a large subarachnoid hemorrhage with effacement of the sulci and 9-mm midline shift. While preparations are made to proceed directly to the operating room, the neurosurgeon asks if you can increase the patient’s mean arterial blood pressure (MAP) from 70 to 90 mm Hg to improve cerebral perfusion. The best vasopressor to accomplish this increase in MAP is
8. Acute renal failure is defined as
A. Urine output of less than 0.5 mL/kg/hr or increase in serum creatinine by 50% in 24 hours
B. Urine output of less than 1 mL/kg/hr or increase in serum creatinine by 100% in 24 hours
C. Urine output of less than 1 mL/kg/hr or increase in serum creatinine by 200% in 24 hours
D. Urine output of less than 0.25 mL/kg/hr or increase in serum creatinine by 50% in 24 hours
9. A 28-year-old man is admitted to the intensive care unit after a motorcycle collision from which he suffers multiple injuries including traumatic aortic injury requiring open repair, multiple long-bone fractures, and a closed head injury. On arrival, his blood pressure is maintained on a norepinephrine infusion. His urine output has been <5 mL/hr for the past 8 hours despite adequate fluid resuscitation and a renal ultrasound study that was normal. His pH on arterial blood gas analysis is 6.9 with a base deficit of 16 and a potassium of 5.4 mEq/L. The decision is made to institute renal replacement therapy for recalcitrant acidosis. The best course of action is
A. Institution of continuous renal replacement therapy (CRRT) as it has been shown to improve mortality at 30 days when compared to intermittent hemodialysis (IHD)
B. Institution of IHD as it has been shown to improve in-hospital mortality when compared to CRRT
C. Institution of IHD as it has been shown to more effectively clear acidosis
D. Institution of CRRT as it has been shown to be more hemodynamically stable than IHD
10. Delirium as defined by the DSM-IV includes which of the following major tenants?
A. Decreased attention and altered cognition
B. Agitation and pulling at lines
C. Altered mental status and dementia
D. Chronic perceptual disturbances and depressed mood
11. Delirium in the ICU setting is
A. A relatively benign condition
B. Associated with increased mortality
C. Associated with a decreased risk of eventual development of dementia
D. Often successfully treated with benzodiazepines
12. An 88-year-old man is admitted to the intensive care unit after a right-hip hemiarthroplasty to repair an intertrochanteric femur fracture sustained during a fall from standing. On postoperative day 1, he is confused and intermittently agitated with a disorganized thought process. His nurse completed the CAM-ICU screen and reports that the result was positive. The next steps in the management should include all of the following, except
A. Continually reorienting the patient to his surroundings
B. Minimizing sedatives if possible
C. Removing all opioids from his pain regimen
D. Optimizing sleep health by minimizing nighttime wakeups and encouraging daily wakefulness
13. All of the following conditions are associated with delirium in the ICU, except
A. Advanced age
B. Orthopedic surgery
D. Sleep deprivation
14. Which of the following is a benefit of enteral nutrition when compared to parenteral nutrition?
A. Decreased cost
B. Decreased length of mechanical ventilation
C. Decreased rates of infection
D. All of the above are benefits of enteral nutrition
15. Enteral nutrition should be initially avoided in a
A. 54-year-old man who presents with acute alcoholic pancreatitis
B. 23-year-old G1P0 with hyperemesis gravidarum
C. 76-year-old woman with a full-thickness esophageal perforation
D. 34-year-old woman hospitalized with an acute exacerbation of ulcerative colitis
16. A 36-year-old G3, now P3, after a normal spontaneous vaginal delivery is complicated by postpartum hemorrhage. Her vitals are checked, and she is noted to be tachycardic with a HR of 132 bpm and hypotensive with a BP of 76/35 mm Hg. The rapid response team is called. As a result of calling the rapid response team, which of the following outcomes can most reasonably be expected?
A. She is less likely to have a cardiopulmonary arrest on the postpartum floor
B. She is less likely to have a cardiopulmonary arrest in the hospital
C. She is less likely to be transferred to an ICU
D. She is more likely to survive to hospital discharge
17. The most significant risk of intensive insulin therapy (goal blood glucose 80–100 mg/dL) when compared to moderate glucose control (goal blood glucose <180 mg/dL) is
A. Myocardial infarction
C. Patient dissatisfaction
18. A 54-year-old man is admitted to the intensive care unit for monitoring after a complicated left colectomy for diverticulitis. He has a history of type 2 diabetes mellitus on metformin. On arrival to the ICU, his blood glucose on an arterial blood gas is 254 mg/dL. One hour later, it is 435 mg/dL. The next appropriate step in his management is
A. Recheck blood glucose in 1 hour
B. Restart home metformin
C. Start IV insulin therapy with a goal glucose <180 mg/dL
D. Start IV insulin therapy with a goal glucose <120 mg/dL
19. A 93-year-old woman is admitted to the ICU with a leaking 7.8-cm abdominal aortic aneurysm. A multidisciplinary discussion is initiated between the patient, family, bedside nurse, ICU team, and surgery team to decide on the next course of action. Select the answer which best identifies the ethical principle at hand in each quote:
A. Autonomy—patient: “I accept that refusing an operation means I will likely die soon, but I want to die at home with my family around me if at all possible”
B. Beneficence—ICU attending: “I worry that if you have this operation it will be unlikely that you will ever return to living at home without significant assistance”
C. Nonmaleficence—surgeon: “The best chance of you surviving is to have the aneurysm repaired”
D. Justice—patient’s daughter: “Is there another way to do the operation that is less risky?”
20. An 86-year-old man with end-stage congestive heart failure and chronic obstructive pulmonary disease is admitted to the intensive care unit after a fall down one flight of stairs from which he sustains a large subarachnoid hemorrhage. After lengthy discussion with the family, including the patient’s wife who has been previously designated his health-care proxy, a decision is made to change goals of care to comfort measures alone. The patient is started on a morphine infusion for pain and to control dyspnea; he is extubated and the family is present at the bedside. About an hour later, the patient’s daughter emerges from the room, and tearfully asks, “How much longer can this go on? Can’t you do something to speed up the process?” You correctly reply
A. “We can add additional sedation which will make him pass more quickly”
B. “I can give him a bolus of morphine to stop him from breathing”
C. “We can increase the rate of the morphine infusion if he appears to be in pain”
D. “We can give him a strong muscle relaxant called rocuronium, which will stop him from breathing”
21. An 89-year-old woman is postoperative day 23 from an open repair of a thoracoabdominal aortic aneurysm. She is bacteremic for a second time, and continues to require vasopressor support, mechanical ventilation, and continuous renal replacement therapy. After the most recent of many multidisciplinary family meetings, the decision is made to withdraw life-sustaining treatment and focus on comfort measures alone. As you are discussing with the bedside nurse the logistics of removing vasopressor support, a nursing student asks, “Isn’t that going to kill her?” The most correct response is
A. “Since our goal is not to end her life, it is not technically killing her”
B. “As long as her heart beats after we turn off the medications, it is not euthanasia”
C. “As long as the family has given us permission it is OK”
D. “Stopping these treatments simply discontinues our prolongation of her natural death”
22. A 45-year-old construction worker falls from a three-story building suffers multiple traumatic injuries including a partial amputation of his left leg, resulting in substantial hemorrhage. He is admitted to the intensive care unit directly from the emergency room having received 4 U of packed red blood cells and 2 U of fresh-frozen plasma. Following further resuscitation and operative repair of his left leg, his serum creatinine is noted to be 2.13 mg/dL, and urine output is 0.3 mL/kg/h. The most likely etiology of his renal failure is
A. Prerenal failure from hypotension
B. Prerenal failure from thromboembolic disease
C. Intrinsic renal failure from rhabdomyolysis
D. Postrenal failure from ureteral obstruction
23. A 28-year-old woman with a history of Hodgkin lymphoma and external beam radiation is admitted to the intensive care unit after repair of an esophageal perforation. She is maintained strictly NPO. Addition of dextrose to her maintenance intravenous fluids will most likely
A. Fail to suppress protein catabolism
B. Improve her blood glucose control
C. Increase her insulin requirement
D. Improve her cardiac metabolic balance
24. Which of the following tissues does not rely on glucose metabolism in the setting of starvation?
A. Neural tissue
B. Cardiac tissue
C. Renal medullary tissue
25. Which of the following parenteral nutrition orders would be least likely to precipitate hypercarbic respiratory failure in a patient with severe chronic obstructive pulmonary disease?
A. Protein = 40 g/L, dextrose = 125 g/L, fat = 0 g/L
B. Protein = 30 g/L, dextrose = 150 g/L, fat = 0 g/L
C. Protein = 50 g/L, dextrose = 60 g/L, fat = 50 g/L
D. Protein = 50 g/L, dextrose = 100 g/L, fat = 25 g/L
26. A 25-year-old man is admitted to the intensive care unit after exploratory laparotomy and repair of multiple bowel injuries from several gunshot wounds. Several hours after admission, the respiratory therapist calls to alert you that his peak airway pressures have increased significantly. The bedside nurse also reports an increase in his vasopressor requirement, and a decrease in urine output. On examination, his abdomen is tense, with a midline dressing intact, and clear breath sounds bilaterally. The most likely diagnosis is
A. Acute myocardial infarction leading to pulmonary edema
B. Hypovolemia from inadequate fluid resuscitation
C. Hemorrhage from an unrecognized injury
D. Abdominal compartment syndrome from bowel edema or hemorrhage
27. One of the feared adverse effects of reinstituting nutrition in a malnourished patient is refeeding syndrome. The most common electrolyte abnormality seen in refeeding syndrome is
A. Hypophosphatemia from an increase in intracellular movement of phosphate
B. Hypokalemia from extracellular buffering of alkalosis
C. Hypomagnesemia from renal losses
D. Hyponatremia from excess free water retention by the kidney
28. A 59-year-old man with acute chronic pancreatitis complicated by pseudocyst and necrotizing pancreatitis has been receiving total parenteral nutrition (TPN) for 3 weeks. An error in the ordering system prevents the pharmacy from receiving his order in time to make that day’s supply. If his TPN is abruptly discontinued, he is at highest risk for
29. Acute respiratory distress syndrome (ARDS) patients’ plateau pressures should be maintained at or below
A. 50 cm H2O
B. 60 cm H2O
C. 40 cm H2O
D. 30 cm H2O
30. Helium–oxygen mixtures can be useful therapies for patients with upper airway obstruction. Compared with air, helium–oxygen mixtures have lower
C. Oxygen content
D. Nitrous oxide content
31. In assist-control ventilation (ACV)
A. Breaths triggered by the ventilator result in the full preset tidal volume being delivered, while breaths triggered by the patient are unsupported by the ventilator
B. All breaths result in the full preset tidal volume being delivered, regardless of whether they are initiated by the ventilator or by the patient
C. All breaths must be initiated by the patient
D. The patient is incapable of triggering breaths
32. A 78-year-old man is admitted from the surgical floor to the intensive care unit for respiratory distress. He is postoperative day 1 from open reduction and internal fixation of a right femoral shaft fracture sustained during a motor vehicle collision. His heart rate is 118 bpm, blood pressure is 104/62 mm Hg, SpO2 is 68% on a non-rebreathing mask at 15 L/min of oxygen, and respirations are 42/min. On examination, he is unresponsive to commands and to sternal rub. The ICU team is deciding whether to initiate noninvasive positive-pressure ventilation (NIPPV) or to perform endotracheal intubation. NIPPV is contraindicated because
A. The patient’s neurologic examination suggests that he is incapable of protecting his airway
B. NIPPV is incapable of improving significantly low oxygen saturations
C. The patient is claustrophobic
D. The patient has certainly suffered a pulmonary embolism (PE), and NIPPV is not helpful in this situation
33. In the first several days following traumatic brain injury requiring mechanical ventilation, an optimal regimen for anxiolysis includes
A. Diazepam bolus every hour
B. Lorazepam infusion
C. Hydromorphone infusion
D. Propofol infusion
34. In pressure-support ventilation (PSV), inspiration ends (and expiration begins) when
A. A preset tidal volume has been achieved
B. A preset airway pressure has been achieved
C. Flow decreases to a preset level
D. A preset amount of time has passed
35. A patient can be diagnosed with acute respiratory distress syndrome (ARDS) if he or she has an acute onset of illness, bilateral infiltrates on chest X-ray, lack of evidence of left heart failure, and a PaO2/FIO2 (P/F) ratio of less than or equal to
A. 500 mm Hg
B. 400 mm Hg
C. 350 mm Hg
D. 200 mm Hg
36. A 25-year-old woman has been in the ICU for 6 days after sustaining multiple life-threatening traumatic injuries. She is suffering from septic shock and acute respiratory distress syndrome (ARDS). On examination, she is dyssynchronous with the ventilator, coughing, grimacing in pain, and tearful. SpO2 is 88% on a FIO2 of 100%, and the BP is 108/58 mm Hg on a low-dose infusion of norepinephrine. The most appropriate plan for management of the patient’s pain, anxiety, and ventilator dyssynchrony is
A. Hydromorphone PRN and a continuous infusion of cisatracurium
B. Fentanyl infusion and a continuous infusion of cisatracurium
C. Midazolam and fentanyl infusions
D. Lorazepam PRN
37. A patient is at greatest risk for requiring endotracheal intubation and mechanical ventilation if the SpO2 is 91% while breathing
A. Room air
B. 4 L/min of oxygen via nasal cannula
C. 15 L/min of oxygen via a non-rebreathing mask with reservoir bag
D. Noninvasive positive-pressure ventilation with an FIO2 of 35%
38. Weaning from mechanical ventilation is expedited by
A. Daily spontaneous breathing trials
B. Synchronized intermittent mandatory ventilation (SIMV)
C. Administration of bronchodilating medications around the clock
D. Daily bronchoscopy
39. Synchronized intermittent mandatory ventilation (SIMV) was an improvement on intermittent mandatory ventilation (IMV) because it
A. Can provide full ventilation support to an apneic patient
B. Can utilize volume-preset or pressure-preset ventilation
C. Allows the patient to breathe spontaneously
D. Reduces the likelihood of breath stacking and volutrauma
40. Tracheostomy should be considered to reduce the risk of subglottic stenosis after an endotracheal tube has been in place for
A. 5 days
B. 10 days
C. 2 to 3 weeks
D. 8 to 10 weeks
41. A 45-year-old alcoholic male was admitted to the medical floor with severe pancreatitis. On hospital day 5, his respiratory status significantly deteriorates and he is transferred to the ICU. The SpO2 is 89% on a non-rebreather mask at 15 L/min oxygen. Upon arrival in the ICU, he is sedated and intubated. Initial ventilator settings should include a set tidal volume of
A. 2 mL/kg
B. 6 mL/kg
C. 10 mL/kg
D. 14 mL/kg
42. A 20-year-old trauma patient requires a large dose infusion of propofol while intubated in the ICU. When the propofol is reduced to attempt a spontaneous breathing trial, the patient thrashes wildly and tries to pull out his arterial and central venous lines. A titratable agent that could prove useful for management of this patient’s agitation while not depressing his respiratory drive is
C. Nitrous oxide
D. Fentanyl transdermal patch
43. For pressure-preset ventilation (also known as “pressure-control ventilation”), the independent variable and dependent variable, respectively, are
A. Tidal volume and FIO2
B. Tidal volume and frequency
C. SpO2 and airway pressure
D. Airway pressure and tidal volume
44. A mechanically ventilated, 70-kg patient has an arterial blood gas of pH = 7.06, PCO2 = 83 mm Hg, and PO2 = 140 mm Hg on volume control ventilation (tidal volume = 450 mL, respiratory rate = 8, FIO2 = 50%, and positive end-expiratory pressure [PEEP] = 8 cm H2O). The most appropriate next step in the management is
A. Increase PEEP
B. Increase FIO2
C. Increase the respiratory rate
D. Administer sodium bicarbonate
45. The primary benefit of positive end-expiratory pressure (PEEP) during mechanical ventilation is
A. Improved elimination of CO2
B. Improved venous return and cardiac output
C. Prevention and reversal of alveolar collapse (atelectasis)
D. Reduction in peak inspiratory pressure
46. A patient with a chronic obstructive pulmonary disease exacerbation has an initial arterial blood gas (ABG) with pH = 7.05, PCO2 = 95 mm Hg, and PO2 = 54 mm Hg on 6 L of oxygen via nasal cannula. The patient is awake, alert, and in moderate respiratory distress with significant wheezing. Bronchodilators and continuous positive airway pressure (CPAP) 10 cm H2O via face mask with FIO2 of 50% are initiated. One hour later, the ABG is pH = 7.10, PCO2 = 90 mm Hg, and PO2 = 92 mm Hg. The patient remains awake and alert and is now in less distress. The most appropriate next step in the management is
A. Increasing the FIO2
B. Increasing CPAP to 15 cm H2O
C. Changing the mode to bi-level positive airway pressure (BiPAP)
D. Stopping CPAP and delivering oxygen via high-flow nasal cannula
47. An ICU patient with severe acute respiratory distress syndrome (ARDS) remains dyssynchronous with the ventilator despite administration of high-dose propofol and fentanyl infusions and changes in the mode of ventilation. The patient’s gas exchange has deteriorated over the course of the day, and hypotension requiring vasopressor support has developed in the setting of increasing the propofol dose. The next best step is to
A. Increase propofol
B. Change to pressure-support ventilation
C. Aggressively diurese the patient
D. Administer a nondepolarizing neuromuscular-blocking agent
48. A 35-year-old man is receiving care in the ICU after sustaining an 80% total body surface area burn from a house fire 5 weeks ago. The surgical team wishes to transition from large dressing changes in the operating room to smaller dressing changes in the ICU. The patient’s analgesic regimen consists of extended-release morphine 60 mg by mouth every 12 hours and hydromorphone 2 to 4 mg IV every 2 hours PRN for breakthrough pain. The most appropriate agent for providing sedation and analgesia during the dressing changes in the ICU is
A. Oral gabapentin
B. Oral clonidine
C. Intravenous morphine
D. Intravenous ketamine
49. A 30-year-old man is admitted to the ICU intubated after a 14-hour spine surgery in the prone position. When he emerges from anesthesia, he bites down on his endotracheal tube, tries frantically to breathe, and panics when he is unable to draw a breath. The nurse boluses propofol and achieves adequate sedation. Five minutes later, the SpO2 rapidly falls from 99% to 65% and the patient appears cyanotic. Pink froth is seen in the endotracheal tube. This complication could have been avoided by
A. Placing a bite block between the patient’s teeth
B. Administration of less IV fluid during the spine surgery
C. Omitting the propofol bolus
D. Positioning the patient in reverse Trendelenburg
50. Effective treatment for carboxyhemoglobinemia includes
A. Sodium nitrite
B. Ventilation with 100% oxygen
C. Ventilation with air
D. Sodium thiosulfate
CHAPTER 19 ANSWERS
1. B. The patient has clinical evidence of shock for which the most common cause is sepsis (likely urosepsis in this case). Primary treatment of vasodilatory shock consists of repleting intravascular volume until adequate preload can be restored, followed by, vasopressor support to maintain adequate end-organ perfusion. The patient’s history as otherwise healthy does not rule out cardiogenic shock but makes it less likely, particularly in the setting of fever. Institution of dobutamine for increased inotropy may be useful in cardiogenic shock but is unlikely to improve vasodilatory shock where cardiac output is typically already elevated. Nitroglycerin infusion can be useful in cases of cardiogenic shock secondary to right-ventricular failure, but in such a case, an elevated central venous pressure would be expected. Finally, while blood transfusion may be indicated to increase oxygen-carrying capacity and oxygen delivery in certain shock states, there is no evidence for a goal hemoglobin concentration of 12 g/dL. Fluid resuscitation should begin with crystalloid until more data can be gathered on the patient’s condition.
2. A. Shock is a common state in the intensive care unit which has many causes. The common result is inadequate tissue perfusion to end organs, resulting in an imbalance between oxygen supply and demand. If treated early, shock is reversible. However, if untreated, shock can progress to irreversible multisystem organ failure and death. While hypotension is a common component of shock, lack of fluid responsiveness is not a part of the definition, nor is inadequate cardiac output.
3. D. In medically complex patients, the etiology of shock can be difficult to diagnose. While by history, one could presume this patient has hypovolemic, septic, or anaphylactic shock, the pulmonary artery catheter indicates elevated right-sided filling pressures with relatively low left-sided pressures, and hypotension, which are consistent with right-ventricular failure and cardiogenic shock.
4. D. The American College of Chest Physicians/Society of Critical Care Medicine (ACCP/SCCM) Consensus Conference Definitions for sepsis would classify this patient as having septic shock. The consensus definition for sepsis is a confirmed or suspected infection plus two of the SIRS criteria (temperature <36°C or >38°C, heart rate >90 bpm, respiratory rate >20 breaths/min or PaCO2<32 mm Hg, leukocyte count <4,000 cells/L or >12,000 cells/L). Severe sepsis is defined as sepsis together with dysfunction of at least one organ system. Septic shock is defined as sepsis plus hypotension (systolic blood pressure <90 mm Hg) despite fluid resuscitation. This patient has a suspected infection, meets at least two of the SIRS criteria, and remains hypotensive despite fluid resuscitation, making the most correct answer septic shock.
5. C. Dopamine has direct agonist action on α1, β1, and DA1 receptors, as well as indirect agonism of α1 and β1 receptors via release of endogenous norepinephrine. DA1 effects are predominately seen in low doses of dopamine and cause renal arteriole dilation. β1 effects are seen at moderate doses of dopamine and increase myocardial contractility and heart rate. Increased myocardial work and oxygen demand resulting from the agonist actions of dopamine can lead to myocardial ischemia. α1 Effects are seen at high doses of dopamine and lead to increased systemic vascular resistance.
6. C. Agents that act on β receptors have effects on a wide variety of organs. β1 activation causes an increase in inotropy and chronotropy as well as stimulation of renin secretion. β2 agonism results in bronchodilation as well as dilation of other smooth muscles, including the uterus.
7. B. Phenylephrine acts directly on α1 receptors to increase systemic vascular resistance, arterial blood pressure, and cerebral blood flow. Phenylephrine does not cross the blood-brain barrier and therefore does not affect the cerebral vasculature, making it the vasopressor of choice in brain-injured patients.
8. A. There are many definitions of acute renal failure (or acute kidney injury). The most consistent definition is a urine output of less than 0.5 mL/kg/hr or a 50% increase in serum creatinine over 24 hours. Both the Acute Dialysis Quality Initiative (ADQI) criteria (also known as the RIFLE criteria) and the Acute Kidney Injury Network (AKIN) criteria include these in the first stage of acute kidney injury.
9. D. CRRT has not been shown to be more efficacious or improve mortality in ICU patients when compared to IHD; however, CRRT is associated with less hypotension presumably because of smaller intravascular fluid shifts when compared to IHD. In this patient who has a persistent vasopressor requirement, CRRT will likely provide more hemodynamic stability, while enabling clearance of both his acidosis and hyperkalemia.
10. A. Delirium is defined by the DSM-IV as an alteration of consciousness with (1) decreased ability to focus or sustain attention associated, (2) a disturbance in cognition or perception not accounted for by baseline dementia. Agitation and pulling at lines may be signs of hyperactive delirium but are not diagnostic of delirium. Dementia is a chronic condition that is diagnostically separate from delirium, which is an acute condition. Depressed mood is not part of the definition of delirium, although flat affect may be seen in hypoactive delirium.
11. B. While previously thought of as a relatively benign condition or a mere inconvenience to ICU providers, delirium has been associated with prolonged mechanical ventilation, prolonged ICU and hospital stay, and increased mortality. Delirium is also associated with eventual development of dementia. Risk of delirium is increased when benzodiazepines are used for sedation.
12. C. While opioids may indeed contribute to delirium, inadequate pain control is also associated with delirium. It may be beneficial to optimize pain control with other nonopioid adjuncts such as acetaminophen, but removal of all opioids may not be practical or helpful. Encouraging sleep health, reorienting the patient to his surroundings, and minimizing sedatives are all important treatments for delirium.
13. B. Advanced age, sepsis, and sleep deprivation have all be associated with delirium. Orthopedic surgery has not been independently associated with delirium. Other conditions associated with delirium include baseline cognitive impairment, increasing severity of illness, multisystem organ failure, immobilization, pain, mechanical ventilation, and use of sedatives (especially benzodiazepines).
14. D. Enteral nutrition is less expensive, easier to administer, and maintains normal enteric physiology and flora better than parenteral nutrition. Enteral nutrition is also associated with lower rates of infection, and more recently has been shown to decrease the length of mechanical ventilation and hospital stay (even in a subset of patients who have limited enteral intake).
15. C. While previous concerns have been raised about enteral feeding in a number of disease states, more recent evidence demonstrates the benefits outweigh the risks in cases of acute pancreatitis, hyperemesis gravidarum, and inflammatory bowel disease, as well as cases of enteric fistulas, short-bowel syndrome, and bone marrow or other chemotherapy patients. Patients with an esophageal perforation are managed without enteral nutrition in the acute setting.
16. A. The institution of multidisciplinary rapid response teams were in reaction to the high number of cardiopulmonary arrests seen in the in-hospital setting. Despite this intervention, there are no data to demonstrate decreased incidence of cardiopulmonary arrest in the hospital, prevention of ICU admission, or decreased mortality. However, patients evaluated by the rapid response team are more likely to be moved to the ICU sooner, and therefore less likely to have a cardiopulmonary arrest outside of the ICU, such as on the postpartum floor.
17. D. Initial studies of intensive insulin therapy (goal blood glucose approximately 80–100 mg/dL) suggested decreased ICU mortality. Unfortunately, subsequent trials have failed to reproduce the benefit of decreased mortality and have demonstrated substantial increases in rates of hypoglycemia. While myocardial infarction and seizure may be presentations of hypoglycemia, the more likely underlying cause in the case of intensive insulin therapy is hypoglycemia.
18. C. The patient has a rapidly increasing blood glucose level that warrants control immediately. Restarting home metformin, while reasonable, is unlikely to have an acute effect on his hyperglycemia. IV insulin therapy is indicated in this patient. While earlier studies demonstrated a mortality benefit to intensive insulin therapy, subsequent data have shown an increased risk of hypoglycemia and failed to show a mortality benefit. It would be most reasonable to start IV insulin with a goal blood glucose of <180 mg/dL.
19. A. End-of-life discussions should protect a patient’s right to die with dignity. Understanding the ethical principals at play can help guide balanced solutions. Autonomy recognizes the right of the individual (in this case, the patient) to self-determination. In this case, accepting refusal of treatment with a rational understanding respects the patient’s autonomy. Beneficence is the principle of taking the action that best serves the patient’s interest. The ICU attending, while expressing beneficence is also expressing nonmaleficence, is the concept of avoiding harm to patients. The surgeon is more clearly expressing the ideal of beneficence. Justice refers to the distribution of scarce resources. The question from the patient’s daughter of doing the procedure in a less-risky manner is more likely reflective of beneficence and nonmaleficence.
20. C. The goal of medications at the end of life should be the treatment of specific symptoms, not the direct hastening of death. In this case, treating pain or dyspnea with morphine is quite appropriate. The principle of the “double effect,” that is, two consequences caused by a single action, is also appropriate at the end of life. In this instance, morphine may have the desired effect of treating pain (following the ethical principle of beneficence) but may also hasten death (following the ethical principle of nonmaleficence). It is not ethically appropriate to add sedation to hasten death, or to bolus morphine or a paralytic to stop breathing.
21. D. It is important to communicate to family members and providers that withdrawal of life-sustaining treatment is no different from having a patient (or family member) refuse life-sustaining treatment in the first place, and respects the principle of autonomy. Furthermore, withdrawal of life-sustaining treatment is not active euthanasia but rather cessation of the prolongation of natural death. This is true regardless of the physiologic consequences. Whereas, medications at the end of life are often given with the understanding of the “double effect” principle, namely that medications given to alleviate pain and suffering may also speed death; withdrawal of life-sustaining treatment does not have a specific goal other than to respect the patient and family member’s autonomy, or to cease medically futile care.
22. A. In this vignette, the patient’s massive hemorrhage likely leads to prerenal failure from both hypotension and hypovolemia. Evaluation of the urine would likely reveal an elevated specific gravity and a fractional excretion of sodium of <1%. Thromboembolic disease is possible, particularly with long-bone fractures, although much more rare. Rhabdomyolysis is also possible due to muscle injury but less likely. Finally, while urine output does not rule out obstruction, there is no mention of an injury that would increase suspicion of renal-outflow obstruction.
23. A. Addition of dextrose to intravenous fluids during acute illness does not suppress protein catabolism. Even the addition of adequate calories may not entirely prevent protein catabolism in a critically ill patient. The amount of dextrose in standard maintenance fluids is unlikely to improve her glucose control or substantially alter her insulin requirements. The heart preferentially relies on fatty acid metabolism, which is likely unchanged in the setting of additional IV dextrose.
24. B. Within approximately 24 hours of the onset of fasting, glycogen supplies are depleted and gluconeogenesis becomes increasingly important. Neural tissue, renal medullary tissue, and erythrocytes continue to utilize glucose, sparing tissue proteins, while other cells preferentially utilize fatty acids such as cardiac myocytes.
25. C. The respiratory quotient (RQ) is defined as the ratio of the amount of carbon dioxide produced relative to the amount of oxygen consumed (VCO2/VO2). The RQ changes with the type of caloric intake. Carbohydrates have an RQ of 1, whereas proteins have an RQ of 0.8 to 0.9, and lipids have an RQ closer to 0.7. Given that a higher RQ reflects greater CO2 production, and therefore, increased need for CO2 elimination, the parenteral nutrition with the least calories from carbohydrates will be least likely to precipitate hypercarbic respiratory failure.
26. D. While all of these diagnoses are important to exclude, the most critical in this case is abdominal compartment syndrome. The increase in peak airway pressures, worsening hypotension, and decreased urine output in the setting of recent abdominal surgery with a tense abdomen raise concern for abdominal compartment syndrome. Bladder pressure can be measured as an indicator of intra-abdominal pressure. Myocardial infarction is unlikely in a 25-year-old, and clear lung sounds make pulmonary edema also unlikely. Hypovolemia and hemorrhage are also both possible, but intra-abdominal compartment syndrome should be ruled out first.
27. A. Hypophosphatemia is commonly seen in critically ill patients. As a part of the refeeding syndrome, there is increased synthesis of intracellular adenosine triphosphate, resulting in increased intracellular transport of phosphates. Hypokalemia may also be seen in refeeding syndrome but is related to intracellular transport and secondary effects of endogenous and exogenous insulin. Hypomagnesemia may also occur in refeeding syndrome. Hyponatremia is not commonly associated with refeeding syndrome.
28. C. Given the patient’s long-term TPN use, he is at highest risk for hypoglycemia, as his constant source of glucose has been acutely removed. If TPN is to be discontinued, then it should be slowly tapered over a period of hours. If TPN is to be abruptly discontinued, then it should be replaced with a dextrose-containing fluid. Patients who receive insulin in their TPN are also at risk of hyperglycemia.
29. D. Multiple studies have shown a mortality benefit when patients with ARDS are ventilated with tidal volumes of 6 mL/kg ideal body weight and have plateau pressures maintained at or below 30 cm H2O.
30. A. Helium-oxygen mixtures have a lower density than air, which promotes improved laminar gas flow across obstructed airways. The mixtures have a similar viscosity to air. Helium-oxygen mixtures do not have oxygen content lower than 21% (the oxygen content of air). Neither the mixtures nor the air contains nitrous oxide.
31. B. The essence of ACV is that all breaths receive the full preset tidal volume regardless of whether the breaths are initiated by the ventilator or by the patient. With ACV if the ventilator is set at Vt = 500 mL, the frequency is set at 10 breaths/min, and the patient exhibits no respiratory effort, the ventilator will deliver 500 mL breaths 10 times per minute. If that same patient makes 8 respiratory efforts in addition to the 10 mandatory breaths, the ventilator will deliver 500 mL breaths 18 times per minute. Choice A is not correct because in assist-control mode, all breaths are fully supported. Choice C is not correct because in assist control, if the patient makes no respiratory effort, the ventilator will provide breaths at the preset frequency. Choice D is not correct because assist control does allow patients to trigger breaths.
32. A. Unresponsive patients are poor candidates for NIPPV because of the risk of regurgitation and aspiration of stomach contents. When considering NIPPV, one must consider whether the patient will be able to protect the airway. Choice B is incorrect because NIPPV can, in fact, improve significantly low oxygen saturation, particularly in cases of chronic obstructive pulmonary disease exacerbations or congestive heart failure. Choice C is incorrect because the question does not mention claustrophobia. While it is difficult for patients with claustrophobia to tolerate NIPPV, modern devices that fit over the nose alone have alleviated this problem to some degree. Choice D is incorrect because it is not certain that the patient has suffered a PE. The clinical scenario is suggestive of PE (trauma, long-bone fracture, status postsurgery), but patients with postoperative pulmonary edema and other etiologies of respiratory failure can present in a similar way.
33. D. Propofol infusion is an excellent choice for anxiolysis in mechanically ventilated patients after acute brain injury because of its favorable pharmacokinetics and pharmacodynamics. The ICU team can stop the propofol infusion frequently and reevaluate the patient’s neurologic exam. Choice A is incorrect because hourly boluses of diazepam would result in accumulation of the drug and interfere with neurologic examinations. Choice B is incorrect because a lorazepam infusion is also likely to interfere with neurologic examination. Choice C is incorrect because the question is about anxiolysis, not analgesia.
34. C. In PSV, inspiration is triggered by a patient’s respiratory effort. A continuous airway pressure is maintained by gas flow that decreases throughout inspiration. When flow decreases to a preset fraction of the peak flow (usually 25% of peak flow), gas flow into the inspiratory limb ends and expiration begins. Choice A describes volume-preset ventilation, often called “volume control.” Choice B is incorrect because in PSV, a preset airway pressure is maintained throughout inspiration. Choice D is incorrect because in PSV, decrease in flow (not a preset time) determines the length of inspiration.
35. D. The American-European Consensus Conference (AECC) on ARDS defined ARDS as (1) acute onset and (2) P/F ≤200 mm Hg, bilateral infiltrates on chest X-ray, and a pulmonary artery occlusion (wedge) pressure ≤18 mm Hg or clinical absence of left-atrial hypertension. The pulmonary process was defined at Acute Lung Injury if the above criteria were met but the P/F was 201 to 300 mm Hg. In 2012, the ARDS Definition Task Force removed Acute Lung Injury from the definition and replaced it with the categories mild, moderate, and severe ARDS defined by P/F ratios of 201 to 300, 101 to 200, or ≤100, respectively. The new definition is known as the Berlin definition of ARDS. Only choice D has a P/F ratio low enough to be called ARDS by the AECC or the Berlin definition.
36. C. The combination of an opioid with a benzodiazepine addresses both pain and anxiety and is effective in helping many ARDS patients achieve synchrony with the ventilator. While they can have a significant effect on hemodynamics, both fentanyl and midazolam (in modest doses) are relatively well tolerated by the septic patient suffering from hypotension requiring vasopressors. Choices A and B are incorrect because they involve neuromuscular blockade without any amnestic/anxiolytic agent. Choice D is incorrect because the patient appears to be in pain and lorazepam lacks analgesic properties. Additionally, cough suppression is a quality of opioids that are lacking in benzodiazepines.
37. C. The non-rebreathing mask with reservoir bag can deliver an FIO2 of nearly 100% when oxygen flow is 15 L/min or greater. An SpO2 of 91% on an FIO2 of 100% should alert the clinician to the likely need for endotracheal intubation and mechanical ventilation. Choice A is clearly incorrect as the FIO2 is only 21%. Choice B is incorrect because the FIO2 is only 35% and can be further increased. Choice D is incorrect assuming that other variables are safe and stable (PaCO2, mental status, ability to protect airway). Many chronic obstructive pulmonary disease patients in the ICU benefit from short-term support from noninvasive positive-pressure ventilation and do quite well with SpO2 readings in the low 90s.
38. A. Many studies have sought to determine the factors that result in the fastest time to weaning from mechanical ventilation. The daily spontaneous breathing trial has emerged as a simple maneuver that consistently results in fewer days on mechanical ventilation. Choice B is incorrect because SIMV has not been shown to reduce days on mechanical ventilation. Choice C is not correct because blanket administration of bronchodilating medications has not been shown to expedite weaning from the ventilator. Choice D is not correct because unnecessary bronchoscopy exposes the patient to the risks of the procedure without benefit.
39. D. Choices A, B, and C describe features that are common to both IMV and SIMV. SIMV allows a patient’s respiratory effort to initiate mandatory ventilator-supported breaths; while in IMV, the mandatory breaths are delivered on a preset schedule without regard for the patient’s spontaneous breaths. Therefore, ventilation with IMV has a higher risk of breath stacking and volutrauma, as a patient can take a large spontaneous breath just prior to the ventilator delivering a mandatory breath.
40. C. The risk of subglottic tracheal stenosis increases after an endotracheal tube has been in place for 2 to 3 weeks. There is a trend toward performing early tracheostomy, which may facilitate weaning from the ventilator. Waiting 8 to 10 weeks to perform tracheostomy on an intubated patient would put the patient at undue risk for tracheal stenosis.
41. B. This severe pancreatitis patient is at high risk for acute respiratory distress syndrome (ARDS). When compared with the tidal volume of 12 mL/kg, 6 mL/kg was shown to reduce mortality in patients with ARDS. Choice A is incorrect because 2 mL/kg is not larger than anatomic dead space, so it would lead to progressive respiratory acidosis and hypoxia. Choices C and D are incorrect because these tidal volumes are too large for a patient at risk for ARDS.
42. B. Dexmedetomidine is a titratable, intravenous α2-receptor agonist with sedative and anxiolytic effects. Compared with propofol, benzodiazepines, and barbiturates, it causes less respiratory depression. This makes the drug well suited for cases in which the patient oscillates between apnea/unresponsiveness on large doses of propofol or benzodiazepines, and extreme agitation on lower doses. Young trauma patients being weaned from mechanical ventilation often tolerate the endotracheal tube very poorly, and some benefit from dexmedetomidine in the period leading up to extubation. Choice A is incorrect because methadone, with its complex pharmacokinetic profile, is difficult to titrate over a short period of time and would not provide direct anxiolysis. Choice C is incorrect because nitrous oxide is an impractical agent for use in the ICU. Choice D is incorrect because a transdermal fentanyl patch would be difficult to titrate over a short period of time and would not provide direct anxiolysis.
43. D. With mechanical ventilation, the “independent variable” is manipulated or “set” by the operator, while the dependent variable results from the system and cannot be “set” by the operator. In pressure-preset ventilation, the inspiratory airway pressure is set to a desired value, and thus is an independent variable. The tidal volume is not set; rather, it results from a combination of variables within the system, including the set inspiratory airway pressure, lung compliance, chest-wall resistance, and the set inspiratory time. Thus, tidal volume is a dependent variable. In volume-preset ventilation, or “volume control ventilation,” the opposite is true; the independent variable is tidal volume, and the dependent variable is airway pressure. Choice A is incorrect because tidal volume is not an independent variable and FIO2 is not a dependent variable. Choice B is incorrect because tidal volume is not an independent variable and frequency is not a dependent variable. Choice C is incorrect because SpO2 is never an independent variable and airway pressure is not a dependent variable in pressure-preset ventilation.
44. C. This is a case of nearly pure respiratory acidosis. The pH is very low as a result of a significantly elevated PCO2. The management of a respiratory acidosis consists of increasing the minute ventilation by increasing either respiratory rate (choice C) or tidal volume (not given as an answer choice). Choices A and B are incorrect because neither would result in an increased minute ventilation. Choice D is incorrect because giving bicarbonate will temporarily increase the pH, but will not address the underlying problem of inadequate elimination of CO2.
45. C. PEEP helps to expand collapsed alveoli, which improves ventilation/perfusion matching by reducing shunt. Choice A is incorrect because PEEP does not directly impact ventilation, which determines the elimination of CO2. Choice B is incorrect because PEEP typically reduces venous return, which in turn reduces the cardiac output. Choice D is incorrect because in general, the peak inspiratory pressure will increase when PEEP is added.
46. C. The patient is tolerating CPAP well, and oxygenation has improved, but ventilation remains inadequate. By changing modes to BiPAP, inspiratory pressure will be added, which will likely increase ventilation and improve the hypercarbic respiratory acidosis. Choices A, B, and C are incorrect because the patient’s arterial oxygen level is adequate, and increasing the FIO2 or CPAP would cause an increase in PaO2.
47. D. In cases of severe ARDS and ventilator dyssynchrony refractory to high-dose sedatives and opioids, neuromuscular blockade is appropriate. The risk of polymyoneuropathy of critical illness is increased by the use of neuromuscular-blocking agents, but the immediate risks of hypoxemia and hypoventilation are more pressing. Choice A is incorrect because the patient is already on high-dose propofol with adverse effect (worsening hypotension). Choice B is incorrect because the patient is already failing on full ventilator support. A change to pressure-support ventilation would almost certainly result in worsened oxygenation. While diuresis has a role in the care of patients with refractory hypoxemia, choice C is incorrect because the patient is hypotensive. Adding hypovolemia to a distributive shock patient could result in hemodynamic collapse.
48. D. Ketamine is an N-methyl-D-aspartate antagonist with dissociative and analgesic effects. It also has sympathomimetic effects, so it will often cause an increase in heart rate and blood pressure. It has minimal effect on respiratory drive. This combination of qualities makes it well suited for procedural sedation in ICU patients, especially for those patients who have developed tolerance to opioids and GABAergic agents. Choices A and B are clearly incorrect because oral medications are impractical for procedural sedation in the ICU. Choice C is incorrect because the patient is already on large doses of hydromorphone and morphine, is likely to have developed tolerance to opioids, and therefore, is unlikely to have a significant response to additional morphine administration.
49. A. This patient is suffering from negative-pressure pulmonary edema resulting from the patient’s strong respiratory effort, which generates a large negative intrathoracic pressure in the setting of an occluded airway. In this setting, the large negative pressure in the alveoli pulls fluid from pulmonary capillaries into the airspaces. This can result in the immediate onset of severe pulmonary edema, shunt, and hypoxia. A bite block prevents occlusion of the endotracheal tube.
50. B. The half-life of carboxyhemoglobin is reduced significantly by ventilation with 100% oxygen. Choices A and D are treatments for cyanide poisoning. Ventilation with air would greatly prolong the time to resolution of carboxyhemoglobinemia.