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ABA Critical Care practice questions

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Question 1Respiratory disorders and mechanical ventilation

A patient with ARDS is receiving 8 cmH2O PEEP and has a PaO2/FiO2 ratio of 260. According to the Berlin definition, which category applies?

  1. No ARDS because the ratio exceeds 200
  2. Mild ARDS Correct answer.
  3. Severe ARDS
  4. Moderate ARDS

Explanation

The Berlin definition classifies ARDS as mild when PaO2/FiO2 is 200–300, moderate when 100–200, and severe when 100 or less, provided PEEP is at least 5 cmH2O. A ratio of 260 with PEEP 8 therefore meets mild ARDS criteria. The presence of PEEP support and a compatible clinical picture is required for the diagnosis.

Question 2Respiratory disorders and mechanical ventilation

Which initial tidal volume target is recommended for a patient with ARDS who has a predicted body weight of 70 kg?

  1. 840 mL (12 mL/kg)
  2. 420 mL (6 mL/kg) Correct answer.
  3. 700 mL (10 mL/kg)
  4. 280 mL (4 mL/kg)

Explanation

Lung-protective ventilation in ARDS uses tidal volume set to predicted body weight, with an initial target of 6 mL/kg. For a predicted body weight of 70 kg, this equals 420 mL. Volumes as low as 4–5 mL/kg may be used if plateau pressure remains elevated.

Question 3Respiratory disorders and mechanical ventilation

A hemodynamically stable patient with a COPD exacerbation has pH 7.28, PaCO2 68 mm Hg, and persistent respiratory distress despite bronchodilators. Which support is best supported by evidence?

  1. High-flow nasal oxygen alone
  2. Sedation and observation
  3. Noninvasive ventilation Correct answer.
  4. Immediate invasive ventilation

Explanation

Noninvasive ventilation reduces intubation rates and mortality in COPD exacerbations with acute hypercapnic respiratory acidosis when no contraindication is present. The patient is stable enough for a trial, and NIV is the preferred first-line support. Invasive ventilation is reserved for failure or contraindications to NIV.

Question 4Respiratory disorders and mechanical ventilation

In moderate-to-severe ARDS, which prone positioning protocol has been associated with a mortality benefit?

  1. Prone only when P/F falls below 80
  2. Prone for at least 16 h/day Correct answer.
  3. Awake prone positioning for 1 hour
  4. Prone for 2 hours once daily in all patients

Explanation

A landmark trial showed improved survival when patients with moderate-to-severe ARDS were placed prone early and maintained prone for prolonged sessions, approximately 16 hours per day. Short or purely rescue-based prone sessions have not shown the same mortality benefit. Prone positioning should be paired with lung-protective ventilation.

Question 5Respiratory disorders and mechanical ventilation

A patient breathing spontaneously has a respiratory rate of 30/min and a tidal volume of 300 mL. What is the rapid shallow breathing index, and does it favor weaning?

  1. 300, which does not favor weaning
  2. 10, which favors weaning
  3. 90, which favors weaning
  4. 100, which favors weaning Correct answer.

Explanation

The rapid shallow breathing index is respiratory rate divided by tidal volume in liters. Here, 30 divided by 0.300 L equals 100. A value below 105 is generally associated with a higher likelihood of successful weaning.

Question 6Respiratory disorders and mechanical ventilation

For a COPD patient with chronic hypercapnia, which SpO2 target reduces the risk of worsening hypercapnia while maintaining oxygenation?

  1. 98–100%
  2. 88–92% Correct answer.
  3. 85–87%
  4. 94–98%

Explanation

Patients with COPD who are at risk for hypercapnic respiratory failure are generally targeted to an SpO2 of 88–92%. This range provides adequate oxygenation while limiting excessive oxygen administration. Higher oxygen targets can worsen ventilation-perfusion mismatch and increase PaCO2 in susceptible patients.

Question 7Respiratory disorders and mechanical ventilation

A ventilated asthma patient has a set PEEP of 5 cmH2O. During an end-expiratory hold, total PEEP is 12 cmH2O. What is the auto-PEEP?

  1. 5 cmH2O
  2. 17 cmH2O
  3. 12 cmH2O
  4. 7 cmH2O Correct answer.

Explanation

Auto-PEEP is calculated as total PEEP measured during an end-expiratory hold minus the applied set PEEP. Subtracting 5 from 12 gives 7 cmH2O. This indicates incomplete exhalation and dynamic hyperinflation.

Question 8Respiratory disorders and mechanical ventilation

Peak inspiratory pressure is 40 cmH2O and plateau pressure is 22 cmH2O. Which conclusion is most likely?

  1. ARDS with low compliance
  2. Pneumothorax
  3. Decreased chest wall compliance
  4. Increased airway resistance Correct answer.

Explanation

A large peak-to-plateau pressure gradient indicates resistance to airflow rather than reduced lung or chest wall compliance. Plateau pressure reflects alveolar pressure, so a normal plateau makes parenchymal stiffness or pneumothorax less likely. Bronchospasm, secretions, or a narrow endotracheal tube can produce this pattern.

Question 9Respiratory disorders and mechanical ventilation

Which plateau pressure is generally targeted during lung-protective ventilation for ARDS?

  1. ≤30 cmH2O Correct answer.
  2. ≤40 cmH2O
  3. ≤10 cmH2O
  4. ≤20 cmH2O

Explanation

A plateau pressure of 30 cmH2O or less is the usual target because higher alveolar pressures increase the risk of barotrauma and ventilator-induced lung injury. Plateau pressure is used rather than peak pressure to estimate alveolar distending pressure. If the target cannot be met, tidal volume is reduced further.

Question 10Respiratory disorders and mechanical ventilation

In which condition is permissive hypercapnia most concerning?

  1. Severe asthma
  2. ARDS with plateau 28
  3. Raised intracranial pressure Correct answer.
  4. COPD with chronic CO2 retention

Explanation

Permissive hypercapnia raises PaCO2 and can increase cerebral blood flow and intracranial pressure. In patients with raised intracranial pressure, this effect may be harmful, so hypercapnia is avoided when possible. Conditions such as severe asthma often tolerate controlled hypercapnia as part of lung-protective ventilation.

Question 11Respiratory disorders and mechanical ventilation

A patient has a plateau pressure of 30 cmH2O and a PEEP of 12 cmH2O. What is the driving pressure?

  1. 18 cmH2O Correct answer.
  2. 30 cmH2O
  3. 42 cmH2O
  4. 12 cmH2O

Explanation

Driving pressure is plateau pressure minus PEEP. Subtracting 12 from 30 gives 18 cmH2O. A driving pressure above approximately 15 cmH2O has been associated with worse outcomes in ARDS.

Question 12Respiratory disorders and mechanical ventilation

A pressure-time waveform shows a concave dip below baseline during inspiration while the patient is active. Which dyssynchrony is most likely?

  1. Ineffective triggering
  2. Auto-triggering
  3. Flow starvation Correct answer.
  4. Double triggering

Explanation

Flow starvation occurs when the ventilator delivers less flow than the patient demands, producing a negative-pressure deflection or scooped airway pressure curve during inspiration. Increasing inspiratory flow or switching to a flow-responsive mode can improve synchrony. It is distinct from triggering abnormalities.

Question 13Respiratory disorders and mechanical ventilation

A patient ventilated for 5 days develops a new infiltrate, fever, leukocytosis, and purulent secretions. Which action is most appropriate before starting antibiotics?

  1. Stop enteral feeding and observe
  2. Order a chest radiograph only
  3. Culture the lower airway Correct answer.
  4. Perform tracheostomy immediately

Explanation

When ventilator-associated pneumonia is suspected, lower respiratory tract cultures should be obtained to guide antibiotic selection. Antibiotics should then be started promptly rather than delayed for culture results. A chest radiograph supports the diagnosis but does not identify the pathogen.

Question 14Respiratory disorders and mechanical ventilation

Before extubation, a patient has no air leak around the deflated endotracheal tube cuff. What does this finding most suggest?

  1. Laryngeal edema Correct answer.
  2. Diaphragmatic paralysis
  3. Neuromuscular weakness
  4. Low lung compliance

Explanation

An absent cuff leak suggests narrowing of the upper airway, most often from laryngeal edema after prolonged intubation. Corticosteroids may be considered, and extubation should be reassessed carefully. The cuff leak test is not a direct test of muscle strength or lung compliance.

Question 15Respiratory disorders and mechanical ventilation

Which patient is most appropriate for a trial of high-flow nasal cannula?

  1. A patient with copious emesis and no gag reflex
  2. Acute hypoxemic failure on 10 L/min oxygen Correct answer.
  3. A patient with impending respiratory arrest
  4. A patient with facial burns and airway obstruction

Explanation

High-flow nasal cannula is used for acute hypoxemic respiratory failure when the patient is not in imminent danger of arrest and has a protected airway. It provides heated, humidified oxygen with some positive pressure and better comfort than a standard mask. It is not a substitute for emergency airway management.

Question 16Respiratory disorders and mechanical ventilation

Which ARDS patient is most likely to benefit from a lung recruitment maneuver?

  1. Large pneumothorax
  2. Severe emphysema with multiple large bullae
  3. Early diffuse ARDS with derecruitment Correct answer.
  4. Unilateral lobar pneumonia

Explanation

Recruitment maneuvers are most plausible in diffuse ARDS with recruitable lung and evidence of derecruitment. They are less useful and potentially harmful when lung disease is focal or when emphysema or pneumothorax is present. Recruitment should always be followed by adequate PEEP to maintain the recruited lung.

Question 17Respiratory disorders and mechanical ventilation

A patient with morbid obesity has a plateau pressure of 28 cmH2O and a PEEP of 15 cmH2O. Which factor most likely causes plateau pressure to overestimate alveolar distending pressure?

  1. High chest wall elastance Correct answer.
  2. Increased airway resistance
  3. High auto-PEEP
  4. Reduced tidal volume

Explanation

Plateau pressure reflects both alveolar pressure and pleural pressure. Obesity increases chest wall elastance and pleural pressure, so the plateau may overestimate the stress applied to the lung. Airway resistance affects peak pressure more than plateau pressure.

Question 18Respiratory disorders and mechanical ventilation

A ventilated patient has a PaCO2 of 60 mm Hg and a mixed expired CO2 of 20 mm Hg. What is the dead space fraction?

  1. 0.80
  2. 0.50
  3. 0.33
  4. 0.67 Correct answer.

Explanation

The dead space fraction is calculated as (PaCO2 − mixed expired CO2) divided by PaCO2. Here, (60 − 20) / 60 equals 0.67. A high dead space fraction indicates that a large portion of ventilation is not participating in gas exchange.

Question 19Respiratory disorders and mechanical ventilation

A patient with ARDS has a plateau pressure of 32 cmH2O, a PEEP of 15 cmH2O, and a tidal volume of 6 mL/kg predicted body weight. Which change best fits lung-protective ventilation?

  1. Reduce tidal volume to 4–5 mL/kg Correct answer.
  2. Increase inspiratory flow
  3. Increase tidal volume to 8 mL/kg predicted body weight
  4. Increase PEEP to 20 cmH2O

Explanation

The plateau pressure is above the usual 30 cmH2O target, and the driving pressure is 17 cmH2O. When plateau pressure remains elevated despite a tidal volume of 6 mL/kg, the next step is to reduce tidal volume toward 4–5 mL/kg if tolerated. Increasing tidal volume or PEEP would raise distending pressures further.

Question 20Respiratory disorders and mechanical ventilation

A patient with severe ARDS has a PaO2/FiO2 ratio of 70 despite PEEP 18 cmH2O, FiO2 1.0, and prone positioning. Which rescue strategy is most appropriate to evaluate?

  1. Immediate tracheostomy
  2. Routine inhaled nitric oxide as definitive therapy
  3. Venovenous ECMO Correct answer.
  4. Increase tidal volume to 10 mL/kg

Explanation

Refractory severe ARDS with profound hypoxemia despite optimized ventilation, high PEEP, and prone positioning should prompt evaluation for venovenous extracorporeal membrane oxygenation. ECMO is a rescue strategy for patients with potentially reversible respiratory failure and an appropriate overall prognosis. It should be considered before irreversible end-organ injury occurs.

Question 21Cardiovascular disorders and hemodynamic monitoring

Which hemodynamic pattern best characterizes cardiogenic shock?

  1. Low central venous pressure with narrow pulse pressure
  2. Low cardiac index with high wedge pressure Correct answer.
  3. Elevated mixed venous oxygen saturation with reduced extraction
  4. High cardiac index with low systemic vascular resistance

Explanation

Cardiogenic shock results from pump failure, so cardiac output falls and filling pressures rise. A low cardiac index with an elevated pulmonary capillary wedge pressure reflects this pattern. Distributive shock instead shows high cardiac output and low systemic vascular resistance.

Question 22Cardiovascular disorders and hemodynamic monitoring

Central venous pressure is most commonly used to estimate which variable?

  1. Systemic vascular resistance
  2. Coronary perfusion pressure
  3. Right ventricular preload Correct answer.
  4. Left ventricular end-diastolic volume

Explanation

Central venous pressure reflects the pressure in the right atrium and vena cava and is used as an estimate of right ventricular preload. It is influenced by venous return, intrathoracic pressure, and ventricular compliance, so it correlates imperfectly with volume status.

Question 23Cardiovascular disorders and hemodynamic monitoring

An elevated serum lactate in a patient with shock most directly indicates which process?

  1. Reduced oxygen consumption by mitochondria
  2. Tissue hypoperfusion with anaerobic metabolism Correct answer.
  3. Increased hepatic lactate clearance
  4. Compensatory respiratory alkalosis

Explanation

Lactate rises when tissues are poorly perfused and oxygen delivery cannot meet metabolic demand, shifting metabolism toward anaerobic pathways. Lactate is also produced by other mechanisms, but in shock it is primarily a marker of hypoperfusion and illness severity. Trend is more useful than a single value.

Question 24Cardiovascular disorders and hemodynamic monitoring

A high pulse pressure variation on an arterial line in a mechanically ventilated patient suggests which condition?

  1. Volume responsiveness Correct answer.
  2. Reduced ventricular compliance
  3. Excessive vasopressor effect
  4. Aortic stenosis

Explanation

During positive-pressure ventilation, stroke volume varies with changes in preload; a large pulse pressure variation indicates that the heart is operating on the steep portion of the Frank-Starling curve. This suggests that cardiac output may increase with fluid administration. The finding requires a controlled ventilatory pattern and a stable rhythm to be reliable.

Question 25Cardiovascular disorders and hemodynamic monitoring

Which finding is a component of Beck triad in cardiac tamponade?

  1. Hypotension Correct answer.
  2. Bradycardia
  3. Widened pulse pressure
  4. Pulmonary crackles

Explanation

Beck triad consists of hypotension, distended neck veins, and muffled heart sounds. It reflects impaired ventricular filling from pericardial fluid under pressure. Tachycardia, not bradycardia, is typical unless the patient is near arrest.

Question 26Cardiovascular disorders and hemodynamic monitoring

Primary percutaneous coronary intervention is the preferred reperfusion strategy for STEMI when it can be delivered within what time frame from first medical contact?

  1. 12 hours
  2. 90 minutes Correct answer.
  3. 6 hours
  4. 24 hours

Explanation

Primary PCI is preferred when it can be performed within 90 minutes of first medical contact, or within 120 minutes if transfer is required. Fibrinolysis is considered when timely PCI is not available and symptoms are within the appropriate window. The 12-hour figure refers to the overall reperfusion window from symptom onset, not the PCI delay target.

Question 27Cardiovascular disorders and hemodynamic monitoring

A 68-year-old with septic shock has a mean arterial pressure of 58 mmHg after 30 mL/kg of crystalloid. Which vasopressor is first-line?

  1. Vasopressin
  2. Phenylephrine
  3. Dopamine
  4. Norepinephrine Correct answer.

Explanation

Norepinephrine is the first-line vasopressor for septic shock because it raises mean arterial pressure with relatively balanced effects on cardiac output and perfusion. Vasopressin or epinephrine may be added for refractory shock. Dopamine is associated with more arrhythmias and is not preferred.

Question 28Cardiovascular disorders and hemodynamic monitoring

A patient with cardiogenic shock has a cardiac index of 1.6 L/min/m², a pulmonary capillary wedge pressure of 24 mmHg, and a mean arterial pressure of 65 mmHg on norepinephrine. Which agent is most appropriate to add?

  1. Dobutamine Correct answer.
  2. Phenylephrine
  3. Fluid bolus
  4. Vasopressin

Explanation

This patient has low cardiac output with a high filling pressure, indicating pump failure rather than hypovolemia. Dobutamine provides inotropic support and may improve cardiac output in cardiogenic shock. Additional fluid would likely worsen pulmonary congestion.

Question 29Cardiovascular disorders and hemodynamic monitoring

A pulmonary artery catheter shows a mixed venous oxygen saturation of 50% in a patient with septic shock and a hemoglobin of 9 g/dL. Which combination best explains this value?

  1. Methemoglobinemia
  2. Arterial hypoxemia alone
  3. Reduced oxygen consumption with high cardiac output
  4. Increased oxygen consumption or reduced cardiac output Correct answer.

Explanation

Mixed venous oxygen saturation falls when tissues extract a greater fraction of delivered oxygen. This can occur with low cardiac output, anemia, hypoxemia, or increased metabolic demand. In sepsis, a low value usually suggests inadequate oxygen delivery relative to demand.

Question 30Cardiovascular disorders and hemodynamic monitoring

An arterial line waveform shows a narrow, overshooting systolic peak and a systolic pressure that reads higher than a cuff pressure. What is the most likely cause?

  1. Air bubble in the transducer
  2. Underdamped tubing Correct answer.
  3. Overdamped tubing
  4. Kinked catheter

Explanation

Underdamping produces resonance in the pressure tubing, which amplifies the systolic peak and can overestimate systolic pressure. Overdamping, by contrast, flattens the waveform and underestimates systolic pressure. A square-wave test helps confirm the dynamic response.

Question 31Cardiovascular disorders and hemodynamic monitoring

A hypertensive patient with acute cardiogenic pulmonary edema is in respiratory distress with a blood pressure of 210/110 mmHg. Which initial therapy is most appropriate?

  1. Norepinephrine infusion
  2. IV furosemide alone after intubation
  3. Rapid 1 L normal saline bolus
  4. Noninvasive ventilation with nitroglycerin Correct answer.

Explanation

In hypertensive acute cardiogenic pulmonary edema, noninvasive ventilation improves oxygenation and reduces work of breathing while nitroglycerin lowers preload and afterload. This combination can stabilize the patient before diuresis takes effect. Intubation is reserved for failure of noninvasive support or severe hypoxemia.

Question 32Cardiovascular disorders and hemodynamic monitoring

In acute type B aortic dissection, which agent is preferred for initial blood pressure control?

  1. Nitroprusside alone
  2. Esmolol first Correct answer.
  3. Nifedipine
  4. Hydralazine

Explanation

Beta-blockade is started before vasodilators in aortic dissection to reduce the rate of pressure rise and shear stress on the aorta. A vasodilator such as nitroprusside may then be added to control blood pressure. Reflex tachycardia from a vasodilator alone can increase shear stress.

Question 33Cardiovascular disorders and hemodynamic monitoring

Which condition reduces the accuracy of thermodilution cardiac output in a patient with a pulmonary artery catheter?

  1. Fraction of inspired oxygen of 0.40
  2. Severe tricuspid regurgitation Correct answer.
  3. Normal sinus rhythm
  4. Hemoglobin of 12 g/dL

Explanation

Thermodilution relies on a predictable change in blood temperature downstream from the injectate. Severe tricuspid regurgitation causes recirculation and loss of the thermal signal, making the measurement unreliable. Other methods, such as Fick or echocardiography, may be needed.

Question 34Cardiovascular disorders and hemodynamic monitoring

A patient with wide-complex tachycardia at 180 bpm is hypotensive and confused. What is the next step?

  1. Adenosine 6 mg IV push
  2. Synchronized cardioversion Correct answer.
  3. Vagal maneuvers
  4. Amiodarone 150 mg over 10 minutes

Explanation

An unstable patient with a tachyarrhythmia and signs of poor perfusion requires immediate synchronized cardioversion. Adenosine and vagal maneuvers are appropriate for stable narrow-complex tachycardia, not for unstable wide-complex tachycardia. Delay in favor of antiarrhythmic infusion risks cardiovascular collapse.

Question 35Cardiovascular disorders and hemodynamic monitoring

Which statement best describes the role of vasopressin in septic shock?

  1. It is the first-line vasopressor for all patients
  2. Added to reduce norepinephrine need in refractory shock Correct answer.
  3. It increases heart rate more than norepinephrine
  4. It is contraindicated with lactate above 4

Explanation

Vasopressin is typically added to norepinephrine in septic shock when mean arterial pressure remains inadequate or to reduce the norepinephrine dose. It acts through V1 receptors and does not rely on adrenergic pathways. It is not the initial vasopressor for routine septic shock.

Question 36Cardiovascular disorders and hemodynamic monitoring

In a patient with anemia and adequate cardiac output, which change most increases oxygen delivery?

  1. Transfusing packed red blood cells Correct answer.
  2. Increasing FiO2 from 0.5 to 1.0 when SaO2 is 98%
  3. Increasing positive end-expiratory pressure
  4. Reducing hemoglobin further

Explanation

Oxygen delivery is the product of cardiac output and arterial oxygen content, and hemoglobin is the main carrier of oxygen. When saturation is already 98%, increasing FiO2 adds little oxygen content. Transfusing red cells increases hemoglobin and therefore oxygen-carrying capacity.

Question 37Cardiovascular disorders and hemodynamic monitoring

Which hemodynamic finding favors cardiac tamponade over constrictive pericarditis?

  1. Prominent y descent on right atrial pressure tracing
  2. Pericardial knock
  3. Pulsus paradoxus Correct answer.
  4. Equal right and left ventricular diastolic pressures

Explanation

Tamponade impairs diastolic filling and exaggerates the normal inspiratory fall in systolic pressure, producing pulsus paradoxus. Constrictive pericarditis classically shows a prominent y descent and equal diastolic pressures. A pericardial knock is associated with constriction.

Question 38Cardiovascular disorders and hemodynamic monitoring

A patient after an inferior myocardial infarction has hypotension, clear lungs, and a pulmonary artery catheter showing right atrial pressure 18 mmHg, right ventricular end-diastolic pressure 18 mmHg, pulmonary capillary wedge pressure 10 mmHg, and cardiac index 1.8 L/min/m². Which diagnosis is most likely?

  1. Acute mitral regurgitation
  2. Ventricular septal rupture
  3. Cardiac tamponade
  4. Right ventricular infarction Correct answer.

Explanation

Right ventricular infarction produces elevated right-sided filling pressures with a relatively low wedge pressure and reduced cardiac output. Clear lungs and inferior MI make this pattern especially likely. Treatment focuses on maintaining right ventricular preload and avoiding excessive vasodilation.

Question 39Cardiovascular disorders and hemodynamic monitoring

A patient with septic shock has a central venous oxygen saturation of 80%, lactate of 2 mmol/L, and persistent hypotension on norepinephrine. Which interpretation is best?

  1. Oxygen delivery is severely inadequate
  2. Hemoglobin must be transfused to 10 g/dL
  3. Oxygen extraction is impaired or shunting is present Correct answer.
  4. Global tissue hypoxia is ongoing

Explanation

A high central venous oxygen saturation in persistent septic shock can indicate impaired oxygen extraction, microcirculatory shunting, or a hyperdynamic state. It does not rule out ongoing tissue dysoxia, but a low saturation would more directly suggest inadequate delivery relative to demand. Management should integrate perfusion markers rather than target the saturation alone.

Question 40Cardiovascular disorders and hemodynamic monitoring

A patient with severe COPD on mechanical ventilation develops hypotension, a central venous pressure of 18 mmHg, and a pulmonary capillary wedge pressure of 16 mmHg with a low cardiac index. Breath sounds are distant and the expiratory flow waveform does not return to baseline. Which action is most appropriate?

  1. Reduce tidal volume Correct answer.
  2. Give a fluid bolus
  3. Start dobutamine
  4. Increase PEEP

Explanation

The failure of expiratory flow to return to baseline suggests dynamic hyperinflation and auto-PEEP, which raise intrathoracic pressure and impair venous return. Reducing tidal volume and respiratory rate allows more complete exhalation and lowers intrathoracic pressure. Fluid loading or increasing PEEP would likely worsen the hemodynamic compromise.

Question 41Neurologic critical care

A patient with a large right-sided epidural hematoma develops a fixed, dilated right pupil. Which structure is most likely compressed?

  1. Right trigeminal nerve
  2. Right optic nerve
  3. Right oculomotor nerve Correct answer.
  4. Right abducens nerve

Explanation

Uncal herniation shifts the medial temporal lobe over the tentorial edge and compresses the ipsilateral oculomotor nerve. The parasympathetic fibers that run on the surface of the nerve are lost first, producing a dilated, nonreactive pupil before extraocular muscle weakness appears.

Question 42Neurologic critical care

Which agent is recommended as first-line therapy for convulsive status epilepticus?

  1. Oral carbamazepine
  2. Intravenous mannitol
  3. Intravenous lorazepam Correct answer.
  4. Intravenous propofol

Explanation

Benzodiazepines act first because they rapidly enhance GABA-A mediated inhibition, breaking the seizure before neuronal injury accumulates. Lorazepam is favored in most protocols over diazepam because of its longer duration of action.

Question 43Neurologic critical care

A head-injured patient has a brief loss of consciousness, a lucid interval, then rapid deterioration. CT shows a biconvex, lens-shaped collection. What is the diagnosis?

  1. Subdural hematoma
  2. Epidural hematoma Correct answer.
  3. Subarachnoid hemorrhage
  4. Intraparenchymal hemorrhage

Explanation

Epidural blood collects between skull and dura, usually from a torn middle meningeal artery, so it expands quickly and can produce the classic lucid interval. Its biconvex shape is limited by cranial suture lines, where the dura is tightly adherent.

Question 44Neurologic critical care

In a patient with acute transtentorial herniation, which PaCO2 target is used for brief hyperventilation?

  1. 25 to 30 mmHg
  2. 20 to 25 mmHg
  3. 30 to 35 mmHg Correct answer.
  4. 40 to 45 mmHg

Explanation

Lowering PaCO2 to roughly 30 to 35 mmHg constricts cerebral arterioles, reduces cerebral blood volume, and lowers intracranial pressure within minutes. The effect is used only as a temporizing bridge because more aggressive hypocapnia risks cerebral ischemia.

Question 45Neurologic critical care

Which intracranial pressure range is generally considered normal in a resting adult?

  1. 20 to 25 mmHg
  2. 0 to 2 mmHg
  3. 5 to 15 mmHg Correct answer.
  4. 25 to 30 mmHg

Explanation

Normal adult intracranial pressure is approximately 5 to 15 mmHg, and sustained values above about 20 mmHg are generally treated. Pressures in that elevated range after traumatic brain injury are associated with worse neurologic outcomes.

Question 46Neurologic critical care

A patient with a T4 spinal cord injury develops a sudden severe headache, sweating, and blood pressure of 210/110 mmHg. What is the most likely trigger?

  1. Meningitis
  2. Severe anemia
  3. Distended bladder Correct answer.
  4. Hypoglycemia

Explanation

Autonomic dysreflexia occurs with lesions above T6, where a noxious stimulus below the injury produces unopposed sympathetic outflow and paroxysmal hypertension. Bladder distension is the most common trigger, so relieving it and sitting the patient upright are the first steps.

Question 47Neurologic critical care

A patient with traumatic brain injury has a mean arterial pressure of 78 mmHg and an intracranial pressure of 24 mmHg. What is the cerebral perfusion pressure and how should it be interpreted?

  1. 102 mmHg, above the recommended target
  2. 54 mmHg, below the recommended target Correct answer.
  3. 54 mmHg, within the recommended target
  4. 24 mmHg, within the recommended target

Explanation

Cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure, so 78 minus 24 gives 54 mmHg. Guidelines recommend keeping CPP between roughly 60 and 70 mmHg after traumatic brain injury, so this patient needs either ICP reduction or MAP support.

Question 48Neurologic critical care

Which medication improves neurologic outcome when given to patients with aneurysmal subarachnoid hemorrhage?

  1. Dexamethasone
  2. Phenytoin
  3. Mannitol
  4. Nimodipine Correct answer.

Explanation

Nimodipine, a dihydropyridine calcium channel blocker, reduces delayed cerebral ischemia and poor outcomes after aneurysmal subarachnoid hemorrhage. Its benefit is not fully explained by reversal of angiographic vasospasm, and hypotension limits intravenous administration.

Question 49Neurologic critical care

For comatose survivors of cardiac arrest, which targeted temperature strategy is currently recommended?

  1. Hypothermia only if seizures occur
  2. 32 to 37.5°C for at least 24 hours Correct answer.
  3. Immediate rewarming to 37.5°C
  4. Cooling to 28°C for 48 hours

Explanation

Guidelines recommend actively preventing fever and maintaining a constant temperature between 32 and 37.5°C for at least 24 hours in comatose post-arrest patients. Cooling below 32°C has not improved survival or neurologic outcome and increases arrhythmia and coagulopathy risk.

Question 50Neurologic critical care

In a patient with severe traumatic brain injury who has had no seizures, how long is prophylactic anticonvulsant therapy typically continued?

  1. 12 months
  2. Indefinitely
  3. 6 months
  4. 7 days Correct answer.

Explanation

Early post-traumatic seizures cluster in the first week, and prophylaxis for about 7 days lowers their incidence. Continuing beyond that point does not prevent late post-traumatic epilepsy and exposes the patient to drug toxicity.