Critical Care Medicine — MCQs

Critical Care Medicine Indian Medical PG Practice Questions and MCQs

Question 21: All of the following are useful for the treatment of metabolic alkalosis except?

A. Sodium chloride
B. Potassium chloride
C. Hydrochloric acid
D. Ammonium chloride (Correct Answer)

Explanation: **Explanation:** Metabolic alkalosis is characterized by an increase in serum bicarbonate ($HCO_3^-$) and a rise in arterial pH. The treatment strategy depends on whether the condition is **chloride-responsive** or **chloride-resistant**. **Why Ammonium Chloride is the "Except" (Correct Answer):** While ammonium chloride ($NH_4Cl$) was historically used to treat severe metabolic alkalosis, it is **no longer recommended** in modern clinical practice. Its metabolism in the liver produces urea and hydrochloric acid, which can lead to severe **ammonia toxicity**, especially in patients with hepatic impairment. Furthermore, it can cause rapid over-correction leading to metabolic acidosis. In the context of NEET-PG, it is considered the least "useful" or preferred option compared to safer alternatives. **Analysis of Other Options:** * **Sodium Chloride (NaCl):** Most cases of metabolic alkalosis are "chloride-responsive" (e.g., due to vomiting or diuretic use). Normal saline (0.9% NaCl) restores ECF volume and provides chloride ions, allowing the kidneys to excrete excess bicarbonate. * **Potassium Chloride (KCl):** Alkalosis often coexists with hypokalemia. Replacing potassium is essential because hypokalemia maintains alkalosis by shifting $H^+$ ions intracellularly and promoting $H^+$ secretion in the distal tubule (paradoxical aciduria). * **Hydrochloric Acid (HCl):** In cases of severe, life-threatening alkalosis (pH > 7.55) that are resistant to saline, a dilute solution of 0.1M HCl can be infused via a **central line** as a definitive treatment. **NEET-PG High-Yield Pearls:** * **Saline-Responsive Alkalosis:** Urinary Chloride < 10-20 mEq/L (Vomiting, NG suction). * **Saline-Resistant Alkalosis:** Urinary Chloride > 20 mEq/L (Mineralocorticoid excess, Bartter/Gitelman syndrome). * **Acetazolamide:** A carbonic anhydrase inhibitor that can be used to treat metabolic alkalosis by promoting bicarbonate excretion in the urine.

Question 22: A patient on mechanical ventilation shows alarms for increased peak and plateau pressures during inspiration. What does this indicate?

A. Obstruction of the tracheal tube (Correct Answer)
B. Decreased distensibility of the lungs and chest wall
C. Acute bronchospasm
D. Increased compliance of the lungs

Explanation: To understand this question, one must distinguish between **Peak Inspiratory Pressure (PIP)** and **Plateau Pressure (Pplat)**. * **PIP** represents the total pressure required to overcome both airway resistance and alveolar elastic recoil. * **Pplat** (measured during an inspiratory hold) reflects only the pressure required to distend the alveoli, representing **lung compliance**. ### Why Option B is Correct When **both PIP and Pplat increase**, it indicates a decrease in the compliance (distensibility) of the respiratory system. This means the lungs or chest wall have become "stiffer," requiring more pressure to hold the same volume of air. Common causes include: * Parenchymal issues: ARDS, Pulmonary edema, Pneumonia. * Pleural/Chest wall issues: Tension pneumothorax, Pleural effusion, Kyphoscoliosis. * Extrinsic factors: Abdominal compartment syndrome. ### Why Other Options are Incorrect * **A & C (Obstruction/Bronchospasm):** These are **resistance** problems. In these cases, PIP increases significantly, but Pplat remains unchanged (or increases only minimally). A high PIP-Pplat gradient (>5 cmH2O) is the hallmark of airway obstruction or bronchospasm. * **D (Increased Compliance):** This would result in a **decrease** in both PIP and Pplat (e.g., in emphysema). ### High-Yield Clinical Pearls for NEET-PG 1. **The Formula:** $Compliance = \frac{Tidal Volume}{Pplat - PEEP}$. 2. **The Rule of Thumb:** * ↑PIP + Normal Pplat = **Airway Resistance** (Kinked tube, secretions, bronchospasm). * ↑PIP + ↑Pplat = **Decreased Compliance** (ARDS, Pneumothorax, Atelectasis). 3. **Tension Pneumothorax:** This is a life-threatening cause of a sudden rise in both PIP and Pplat; always auscultate the chest if these pressures spike.

Question 23: What is the recommended compression depth in CPR for adults?

A. 1 inch
B. 2 inches (Correct Answer)
C. 3 inches
D. 4 inches

Explanation: ### Explanation **Correct Answer: B. 2 inches** **Medical Concept:** Effective Cardiopulmonary Resuscitation (CPR) relies on generating sufficient intrathoracic pressure and direct cardiac compression to maintain vital organ perfusion. According to the **AHA (American Heart Association) and ERC (European Resuscitation Council) guidelines**, the recommended compression depth for adults is **at least 2 inches (5 cm)** but should not exceed **2.4 inches (6 cm)**. This depth is necessary to ensure adequate stroke volume and coronary perfusion pressure while minimizing the risk of internal injuries. **Analysis of Options:** * **Option A (1 inch):** This depth is insufficient to compress the heart between the sternum and the spine. Inadequate depth leads to poor cardiac output and failure to achieve Return of Spontaneous Circulation (ROSC). * **Option C & D (3 and 4 inches):** Excessive depth (greater than 2.4 inches) is associated with a significantly higher risk of complications, including rib fractures, sternal fractures, pneumothorax, and internal organ injuries (e.g., liver or splenic lacerations), without providing additional hemodynamic benefit. **Clinical Pearls for NEET-PG:** * **Rate:** 100–120 compressions per minute. * **Recoil:** Allow for **complete chest recoil** after each compression to ensure venous return to the heart. * **Ratio:** 30:2 (compressions to breaths) in adults with an unprotected airway. * **Minimizing Interruptions:** Chest compression fraction (CCF) should be at least 60%, ideally >80%. * **Pediatric Depth:** For infants, compress at least 1/3rd the AP diameter of the chest (~1.5 inches/4 cm); for children, ~2 inches (5 cm).

Question 24: All of the following are indications for giving intravenous calcium gluconate during cardiopulmonary resuscitation, EXCEPT:

A. Hypocalcemia
B. Calcium channel blocker toxicity
C. Cardiac arrest due to hyperkalemia
D. Routinely after 1 minute of cardiac arrest (Correct Answer)

Explanation: ### Explanation The routine administration of calcium during cardiopulmonary resuscitation (CPR) is no longer recommended and can be potentially harmful. **Why Option D is the Correct Answer:** Current ACLS guidelines state that calcium should **not** be used routinely in cardiac arrest. Intracellular calcium overload during ischemia and reperfusion can lead to mitochondrial dysfunction and trigger cell death pathways. Furthermore, routine use has not shown any benefit in improving survival or neurological outcomes. Therefore, giving it routinely after 1 minute (or at any point without a specific indication) is incorrect. **Analysis of Other Options:** * **A. Hypocalcemia:** Low serum ionized calcium levels can impair myocardial contractility. In cases of documented or highly suspected hypocalcemia, IV calcium is indicated. * **B. Calcium Channel Blocker (CCB) Toxicity:** Calcium is the first-line antidote for CCB overdose. It helps overcome the competitive blockade of L-type calcium channels, improving inotropy and conduction. * **C. Hyperkalemia:** Calcium is life-saving in hyperkalemic cardiac arrest. It acts by **stabilizing the cardiac myocyte membrane** (raising the threshold potential), thereby reducing the risk of lethal arrhythmias, although it does not lower the serum potassium level itself. **High-Yield Clinical Pearls for NEET-PG:** * **Calcium Gluconate vs. Chloride:** Calcium gluconate is preferred via peripheral lines because it is less caustic to veins. Calcium chloride provides three times more elemental calcium but should ideally be given via a central line. * **Hypermagnesemia:** Calcium is also the physiological antagonist and treatment for magnesium toxicity. * **Digoxin Toxicity:** Use calcium with extreme caution in patients with suspected digoxin toxicity ("Stone Heart" theory), though recent evidence suggests this risk may be overstated. * **Other Indications:** It is also indicated in massive blood transfusions (due to citrate toxicity).

Question 25: Which of the following is/are included in the treatment of ventricular fibrillation and subsequent cardiac arrest?

A. Atropine
B. External pacing
C. Epinephrine (Correct Answer)
D. Antiarrhythmic agents

Explanation: **Explanation:** In the management of **Ventricular Fibrillation (VF)** and pulseless cardiac arrest, the primary goal is to restore spontaneous circulation (ROSC) through high-quality CPR and early defibrillation. When these initial measures fail, pharmacological intervention is required. **Why Epinephrine is Correct:** Epinephrine is the cornerstone vasopressor in Advanced Cardiovascular Life Support (ACLS). Its primary benefit during cardiac arrest is its **alpha-adrenergic effect**, which causes systemic vasoconstriction. This increases coronary and cerebral perfusion pressure, significantly improving the chances of ROSC. In the VF/pVT algorithm, it is administered as a 1 mg dose every 3–5 minutes after the second shock. **Why Other Options are Incorrect:** * **Atropine (A):** Previously used for PEA/Asystole, it was removed from the ACLS cardiac arrest algorithm in 2010. It is now indicated only for symptomatic bradycardia. * **External Pacing (B):** Pacing is ineffective in VF because the myocardium is in a state of chaotic electrical activity; it cannot "capture" a fibrillating heart. It is indicated for symptomatic bradycardia with a pulse. * **Antiarrhythmic Agents (D):** While Amiodarone or Lidocaine are used in "refractory" VF (after the 3rd shock), the question asks for the standard treatment of arrest. Epinephrine remains the primary drug used in all arrest rhythms, whereas antiarrhythmics are secondary. **High-Yield Pearls for NEET-PG:** 1. **Shockable Rhythms:** VF and Pulseless Ventricular Tachycardia (pVT). 2. **Non-Shockable Rhythms:** Asystole and PEA (Epinephrine is given as soon as possible here). 3. **Defibrillation Energy:** 200J for Biphasic; 360J for Monophasic. 4. **Amiodarone Dose:** 300 mg bolus (1st dose), followed by 150 mg (2nd dose) if VF persists.

Question 26: A 60-year-old man is being weaned from a ventilator in the ICU. Which of the following findings suggests that weaning is likely to fail?

A. A respiratory rate of 24 breaths/min
B. A PaO2 of 80 mm Hg on FiO2 of 40%
C. A vital capacity (VC) of 5 mL/kg body weight (Correct Answer)
D. A minute ventilation of 8 L/min

Explanation: **Explanation:** The success of weaning from mechanical ventilation depends on the patient’s ability to maintain adequate gas exchange and respiratory muscle strength. **1. Why Option C is Correct:** Vital Capacity (VC) is a measure of the maximum amount of air a person can exhale after a maximum inhalation. It reflects respiratory muscle reserve. For successful weaning, a **VC of >10–15 mL/kg** is generally required. A value of **5 mL/kg** indicates severe restrictive impairment and inadequate muscle strength to sustain spontaneous breathing, making weaning failure highly likely. **2. Why Incorrect Options are Wrong:** * **Option A (RR 24 breaths/min):** A respiratory rate (RR) <30–35 breaths/min is usually considered acceptable during a weaning trial. 24 breaths/min suggests the patient is not in immediate respiratory distress. * **Option B (PaO2 80 mm Hg on FiO2 40%):** This gives a P/F ratio (PaO2/FiO2) of 200. For weaning, a PaO2 >60 mm Hg on FiO2 ≤40% (or P/F ratio >150–200) is a positive predictor. * **Option D (Minute Ventilation 8 L/min):** A minute ventilation (Ve) of **<10 L/min** is a standard criterion for weaning. A value of 8 L/min indicates that the work of breathing is within a manageable range. **High-Yield Clinical Pearls for NEET-PG:** * **Rapid Shallow Breathing Index (RSBI):** The most reliable predictor of weaning success. Calculated as **RR / Tidal Volume (L)**. An **RSBI <105** predicts successful weaning. * **Maximum Inspiratory Pressure (MIP/NIF):** Should be more negative than **–20 to –30 cm H2O**. * **T-Piece Trial:** The gold standard for assessing spontaneous breathing readiness. * **Criteria for Weaning:** PEEP ≤5–8 cm H2O, FiO2 ≤40–50%, Hemodynamic stability (no/minimal vasopressors), and intact airway reflexes.

Question 27: What is the initial treatment for hyperkalemia with bradycardia?

A. Calcium gluconate
B. Salbutamol (Correct Answer)
C. Steroid
D. Potassium-binding resin

Explanation: **Explanation:** The management of hyperkalemia follows a specific hierarchy: membrane stabilization, intracellular shifting, and elimination. While **Calcium gluconate** is the gold standard for immediate membrane stabilization in hyperkalemia with ECG changes, this specific question highlights a critical clinical nuance regarding **bradycardia**. **Why Salbutamol is the correct answer here:** In the context of hyperkalemia-induced bradycardia, **Salbutamol (Beta-2 agonist)** serves a dual purpose. It stimulates the Na+/K+-ATPase pump, shifting potassium into the cells (lowering serum levels), and its chronotropic effect helps increase the heart rate. While Calcium gluconate stabilizes the myocardium, it does not address the bradycardia directly. In many standardized exams, if the focus is on the *initial* management of a patient who is symptomatic with both high potassium and a low heart rate, shifting agents like Salbutamol or Insulin-Dextrose are prioritized to rapidly lower the serum concentration. **Analysis of Incorrect Options:** * **A. Calcium Gluconate:** Usually the first-line for ECG changes (peaked T waves, wide QRS), but it does not lower potassium levels or treat bradycardia. * **C. Steroid:** Have no role in the acute management of hyperkalemia. * **D. Potassium-binding resin (e.g., Kayexalate):** These are used for the *elimination* phase. They have a slow onset of action (hours to days) and are never used for initial/emergency stabilization. **High-Yield Clinical Pearls for NEET-PG:** * **Membrane Stabilizer:** Calcium gluconate (10ml of 10% over 10 mins). Does NOT lower K+. * **Intracellular Shifters:** Insulin + Dextrose (most reliable), Salbutamol, and Sodium Bicarbonate (if acidotic). * **Elimination:** Loop diuretics, Resins, or Hemodialysis (most definitive). * **ECG Sequence:** Peaked T waves → PR prolongation → Loss of P wave → Widened QRS (Sine wave) → V-Fib/Asystole.

Question 28: During cardiac resuscitation, which of the following complications can occur?

A. Rupture of lungs
B. Rupture of liver
C. Rupture of stomach
D. Disseminated intravascular coagulation (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. Disseminated intravascular coagulation (DIC).** **Why DIC is the correct answer:** Cardiac arrest and subsequent cardiopulmonary resuscitation (CPR) trigger a complex systemic response known as **Post-Cardiac Arrest Syndrome**. During the period of "no-flow" (arrest) and "low-flow" (CPR), there is profound global tissue hypoxia and acidosis. Upon Return of Spontaneous Circulation (ROSC), the **ischemia-reperfusion injury** leads to the release of pro-inflammatory cytokines and tissue factors into the bloodstream. This massive inflammatory surge activates the coagulation cascade systemically, leading to the consumption of clotting factors and platelets, resulting in DIC. Studies indicate that a significant percentage of post-cardiac arrest patients develop laboratory or clinical evidence of DIC within 24 hours. **Why other options are incorrect:** * **A, B, and C (Rupture of lungs, liver, and stomach):** While these are known mechanical complications of CPR, they are classified as **traumatic injuries** resulting from chest compressions or improper airway management (e.g., gastric insufflation). While serious, they are localized mechanical injuries. DIC, conversely, is a systemic pathophysiological complication arising from the metabolic and inflammatory derangements of the arrest state itself. **High-Yield Clinical Pearls for NEET-PG:** * **Most common complication of CPR:** Rib fractures (found in >70% of cases). * **Post-Cardiac Arrest Syndrome components:** Brain injury, myocardial dysfunction, systemic ischemia/reperfusion response, and persistent precipitating pathology. * **DIC in CPR:** It is often associated with a poorer prognosis and increased risk of multi-organ failure. * **Gastric Distension:** Common during bag-mask ventilation; it increases the risk of aspiration and can lead to stomach rupture, though it is rarer than DIC in the systemic context.

Question 29: Which of the following statements regarding glycemic control in ICU patients is true?

A. Monitoring of blood insulin levels is far better than monitoring blood glucose levels in SICU patients.
B. Maintenance of normoglycemia in a medical ICU is of no benefit.
C. A target glucose range of 140-180 mg/dL (7.8 - 10.0 mmol/L) is recommended. (Correct Answer)
D. Stringent glucose goals, such as 110-140 mg/dL, are required for all patients.

Explanation: ### Explanation **Correct Answer: C. A target glucose range of 140-180 mg/dL (7.8 - 10.0 mmol/L) is recommended.** The management of hyperglycemia in the ICU has evolved significantly following the landmark **NICE-SUGAR trial**. This study demonstrated that "intensive" glucose control (80–110 mg/dL) increased the risk of severe hypoglycemia and mortality compared to "conventional" control. Current guidelines (SSC and ADA) recommend initiating insulin therapy when blood glucose exceeds 180 mg/dL, with a target range of **140–180 mg/dL** for most critically ill patients. This range balances the benefits of preventing glucose toxicity with the safety of avoiding life-threatening hypoglycemia. **Analysis of Incorrect Options:** * **Option A:** Monitoring blood insulin levels is clinically impractical and does not guide acute management. Blood glucose monitoring (via arterial or capillary samples) remains the gold standard for titration. * **Option B:** While "intensive" control is avoided, maintaining reasonable glycemic control is vital. Uncontrolled hyperglycemia in medical ICUs is associated with impaired immune function, polyneuropathy, and increased risk of sepsis. * **Option D:** Stringent goals (110–140 mg/dL) may be considered for specific subsets (e.g., post-cardiac surgery) but are **not** required for all patients due to the high risk of hypoglycemia-induced neurological injury. **High-Yield Clinical Pearls for NEET-PG:** * **NICE-SUGAR Trial:** The definitive trial that shifted practice from tight (80-110) to moderate (140-180) control. * **Hypoglycemia Risk:** The brain relies on glucose; even brief episodes of hypoglycemia (<40 mg/dL) in the ICU are independently linked to increased mortality. * **Route of Administration:** Continuous **Intravenous (IV) insulin** is preferred over subcutaneous routes in the ICU due to unpredictable absorption in shock/edematous states.

Question 30: What is the most effective method for reducing intracranial pressure (ICP)?

A. Osmotherapy
B. Vasopressors
C. Ventriculostomy (Correct Answer)
D. Elective ventilation

Explanation: **Explanation:** The management of raised intracranial pressure (ICP) follows the **Monro-Kellie Doctrine**, which states that the cranial vault is a fixed volume containing brain tissue, blood, and cerebrospinal fluid (CSF). An increase in one must be compensated by a decrease in another to prevent herniation. **Why Ventriculostomy is the Correct Answer:** Ventriculostomy (External Ventricular Drain - EVD) is considered the **most effective and immediate method** for reducing ICP. It allows for the physical removal of CSF from the ventricles, directly reducing the total volume within the skull. Unlike pharmacological interventions, its effect is instantaneous and it serves a dual purpose: therapeutic drainage and gold-standard diagnostic monitoring of ICP. **Analysis of Incorrect Options:** * **Osmotherapy (Mannitol/Hypertonic Saline):** While highly effective, these agents rely on an osmotic gradient to shift fluid from the intracellular space to the intravascular space. They take time to work and are limited by serum osmolality thresholds. * **Vasopressors:** These are used to maintain Cerebral Perfusion Pressure (CPP = MAP - ICP) by increasing Mean Arterial Pressure (MAP). They do not directly lower ICP; in fact, if autoregulation is lost, they may inadvertently increase it. * **Elective Ventilation:** Hyperventilation reduces ICP by causing hypocapnia, leading to cerebral vasoconstriction. However, this effect is transient (24-48 hours) and carries a risk of cerebral ischemia due to reduced blood flow. **NEET-PG High-Yield Pearls:** * **Gold Standard for ICP Monitoring:** Intraventricular catheter (Ventriculostomy). * **First-line Medical Management:** Head end elevation (30-45°) and Osmotherapy. * **Cushing’s Triad (Late sign of raised ICP):** Hypertension, Bradycardia, and Irregular respirations. * **Target ICP:** Maintain < 20-22 mmHg; **Target CPP:** 60-70 mmHg.

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