Critical Care Medicine — MCQs

A 65-year-old patient is on mechanical ventilation for acute respiratory distress syndrome (ARDS). Suddenly, the patient becomes hypotensive, tachycardic, and shows absent breath sounds on the left side with tracheal deviation to the right. What is the most common cause of this in patients receiving mechanical ventilation?

Q44

Which of the following is NOT considered as an indicator of adequate fluid resuscitation?

Q45

Patient of pneumonia on ventilator with wt. 50 kg. RR 14/min, bicarbonate - 18, pH 7.3, pCO2 48 mmHg, pO2 110 mmHg, PEEP 12 cm H2O, tidal volume 420 mL, SpO2 - 100% with FiO2 90%. What is next step in management?

Q46

Which of the following statements given below is incorrect regarding CPR?

Q47

In CPR, number of chest compressions per minute in an adult:

Q48

A patient in shock requires rapid fluid resuscitation. If intravenous (IV) cannulation is not possible, within what time frame should an intraosseous (IO) line be placed?

Q49

A 55-year-old woman was admitted to the intensive care unit with severe lobar pneumonia and septic shock. She remained hypoxemic despite intubation, a high fraction of inspired oxygen, and positive end-expiratory pressure (PEEP). When PEEP was increased further, she paradoxically became more hypoxemic and her blood pressure and central venous hemoglobin saturation fell. What would be your approach?

Q50

A 22-year-old street vendor was found in the park having a seizure. Cops brought him to ER, unaware of any background medical history. He is continuously having seizures for 13 minutes and paramedics are not able to gain intravenous access. You ensure the airway is secure and administer oxygen, however, you are unable to gain intravenous access after two attempts. Blood glucose levels are 80mg%. Which medication would be most suitable to administer at this stage to treat patient's seizure?

Critical Care Medicine Indian Medical PG Practice Questions and MCQs

Question 41: According to the Muir-Barclay formula, which of the following is considered the best colloid for volume replacement?

A. Fresh Frozen Plasma (FFP)
B. Packed Red Blood Cells (PRBC)
C. Dextran 40
D. Albumin (Correct Answer)

Explanation: ### **Explanation: Muir-Barclay Formula and Colloid Replacement** The **Muir-Barclay formula** is a classic calculation used primarily in the management of fluid resuscitation for **burn patients**. It is based on the principle of replacing plasma volume lost due to increased capillary permeability following thermal injury. #### **Why Albumin is the Correct Answer** The formula specifically calculates the volume of **plasma (or a plasma substitute)** required to maintain oncotic pressure and intravascular volume. * **Albumin** is considered the "gold standard" colloid in this context because it is the primary protein responsible for **plasma oncotic pressure**. * The formula divides the post-burn period into six 4-hour or 6-hour intervals, providing a specific volume of colloid (usually **5% Albumin** or reconstituted dried plasma) for each period based on the formula: > **(Total Area of Burn % × Weight in kg) / 2 = Volume (ml) per aliquot.** #### **Analysis of Incorrect Options** * **Fresh Frozen Plasma (FFP):** While FFP contains albumin and clotting factors, it carries risks of transfusion-related acute lung injury (TRALI) and infections. It is reserved for coagulopathies, not routine volume expansion in burns. * **Packed Red Blood Cells (PRBC):** These are used to improve oxygen-carrying capacity in cases of anemia or hemorrhage, not for plasma volume replacement in the acute phase of burn resuscitation. * **Dextran 40:** This is a synthetic colloid. While it expands volume, it can interfere with platelet function and cross-matching, and it lacks the physiological oncotic properties of albumin required by the Muir-Barclay protocol. #### **High-Yield Clinical Pearls for INI-CET** * **Parkland Formula vs. Muir-Barclay:** While Muir-Barclay focuses on **colloids**, the more commonly tested **Parkland Formula** uses **Crystalloids (Ringer’s Lactate)**: $4 \text{ ml} \times \text{Body Weight (kg)} \times \text{TBSA \%}$. * **Rule of Nines:** Always use Wallace’s Rule of Nines to calculate the Total Body Surface Area (TBSA) before applying these formulas. * **End-point of Resuscitation:** Regardless of the formula used, the most reliable indicator of adequate fluid resuscitation is **Urine Output** (Target: $0.5\text{--}1.0 \text{ ml/kg/hr}$ in adults).

Question 42: Patient in hospital was given IVF and patient develops hyperchloremic metabolic acidosis. Which fluid will cause this?

A. RL
B. 5 % dextrose
C. NS (Correct Answer)
D. DNS

Explanation: ***NS*** - **Normal Saline (0.9% NaCl)** contains a **chloride concentration of 154 mEq/L**, which is unphysiologically high (supranormal) compared to plasma (approx. 100 mEq/L). - Rapid infusion leads to the retention of excess chloride and dilution of serum bicarbonate, resulting in a **non-anion gap (hyperchloremic) metabolic acidosis**. *RL* - Ringer's Lactate (RL) is a **buffered solution** because it contains **lactate (28 mEq/L)**, which is metabolized by the liver into bicarbonate. - Because of the bicarbonate precursor (lactate) and a near-physiologic chloride concentration (109 mEq/L), RL tends to **prevent or correct** acidosis, rather than causing it. *DNS* - Dextrose Normal Saline (DNS) still contains the **supranormal chloride concentration** (154 mEq/L) from the normal saline component, posing a similar theoretical risk. - However, it is typically less associated with severe acidosis than pure NS in large volumes, and often the primary differentiating fluid in this context is the **buffered RL**. *5 % dextrose* - **5% Dextrose in Water (D5W)** contains no electrolytes (salt) and is only used to provide free water and small amounts of calories. - Rapid infusion of D5W results in dilution and can cause **hyponatremia** and free water excess, but it cannot precipitate hyperchloremic acidosis.

Question 43: A 65-year-old patient is on mechanical ventilation for acute respiratory distress syndrome (ARDS). Suddenly, the patient becomes hypotensive, tachycardic, and shows absent breath sounds on the left side with tracheal deviation to the right. What is the most common cause of this in patients receiving mechanical ventilation?

A. Barotrauma due to high airway pressure (Correct Answer)
B. Endotracheal tube malposition
C. Oxygen toxicity
D. High tidal volume

Explanation: ### **Explanation** The clinical presentation of sudden **hypotension, tachycardia, absent breath sounds**, and **tracheal deviation** in a ventilated patient is a classic description of a **Tension Pneumothorax**. **1. Why Option A is Correct:** In patients with **ARDS**, the lungs are "stiff" (low compliance), necessitating higher airway pressures to maintain ventilation. **Barotrauma** refers to alveolar rupture caused by high **Peak Inspiratory Pressure (PIP)** or high **Plateau Pressure (>30 cm H₂O)**. This allows air to escape into the pleural space. Under positive pressure ventilation, this air accumulates rapidly, causing a "one-way valve" effect that shifts the mediastinum, compresses the great veins, and leads to obstructive shock (hypotension). **2. Analysis of Incorrect Options:** * **B. Endotracheal tube malposition:** While common (usually right mainstem intubation), it typically causes absent breath sounds on the left but **does not** cause tracheal deviation or sudden hemodynamic collapse unless associated with a secondary pneumothorax. * **C. Oxygen toxicity:** This is a chronic complication of high FiO₂ (>0.6) leading to free radical damage and absorption atelectasis; it does not present with acute surgical emphysema or tension physiology. * **D. High tidal volume:** While high tidal volumes lead to **Volutrauma**, the immediate mechanical cause of a pneumothorax is the resultant high pressure (**Barotrauma**). Barotrauma is the specific term for the complication described. --- ### **High-Yield Clinical Pearls for INI-CET** * **Management:** Tension pneumothorax is a **clinical diagnosis**. Do not wait for a X-ray. Immediate treatment is **Needle Decompression** (traditionally 2nd intercostal space, now preferred in the **5th intercostal space** anterior to the mid-axillary line) followed by an Intercostal Drainage (ICD) tube. * **ARDS Strategy:** To prevent barotrauma, use **Lung Protective Ventilation**: Low tidal volumes (6 mL/kg PBW) and keeping Plateau Pressure **<30 cm H₂O**. * **Early Sign:** A sudden increase in **Peak Airway Pressure** on the ventilator monitor is often the first sign of impending barotrauma.

Question 44: Which of the following is NOT considered as an indicator of adequate fluid resuscitation?

A. Pulse
B. Respiratory rate (Correct Answer)
C. Urine output
D. Blood pressure

Explanation: ***Respiratory rate*** - While an *elevated respiratory rate* can indicate *hypovolemia* or other systemic stress, it is a **less specific** and less direct indicator of the adequacy of *fluid resuscitation* compared to *perfusion parameters*. - Changes in *respiratory rate* can be influenced by many factors such as *pain*, *anxiety*, *metabolic acidosis*, and primary *pulmonary issues*, making it less reliable for guiding *fluid therapy*. *Pulse* - A *decreasing pulse rate* and *improving pulse quality* (becoming stronger and less thready) are good indicators of **improved cardiac output** and *volume status* during *fluid resuscitation*. - A *persistently high* or *weak pulse* suggests ongoing *hypovolemia* or inadequate *fluid replacement*. *Urine output* - *Adequate urine output* (typically >0.5 mL/kg/hr in adults) is a critical indicator of **sufficient renal perfusion** and overall *systemic hydration*. - A *rising urine output* after *fluid administration* signifies that organs are receiving adequate blood flow and *fluid balance* is improving. *Blood pressure* - An *increasing blood pressure*, particularly improvement in *mean arterial pressure*, directly reflects **better systemic perfusion** and resolution of *hypotension* caused by *hypovolemia*. - Normalization of *blood pressure* indicates that the *circulatory volume* is adequate to maintain vital organ function.

Question 45: Patient of pneumonia on ventilator with wt. 50 kg. RR 14/min, bicarbonate - 18, pH 7.3, pCO2 48 mmHg, pO2 110 mmHg, PEEP 12 cm H2O, tidal volume 420 mL, SpO2 - 100% with FiO2 90%. What is next step in management?

A. Increase PEEP
B. Increase tidal volume
C. Decrease fio2 (Correct Answer)
D. Decrease RR

Explanation: **Decrease FiO2** - The patient has an **SpO2 of 100% with a FiO2 of 90%**, indicating **hyperoxia** induced by excessive oxygen delivery. - Decreasing FiO2 is the appropriate next step to prevent **oxygen toxicity** (e.g., absorption atelectasis, free radical damage) while maintaining adequate oxygenation. *Increase PEEP* - The patient's **PaO2 of 110 mmHg** is already well within the normal to high range, suggesting that oxygenation is adequate. - Increasing PEEP would be considered if the patient had **refractory hypoxemia**, not hyperoxia. *Increase tidal volume* - The current tidal volume of **420 mL for a 50 kg patient (8.4 mL/kg)** is already at the higher end of lung-protective ventilation (typically 6-8 mL/kg). - Increasing tidal volume further could lead to **ventilator-induced lung injury** (VILI) due to volutrauma, especially in a patient with pneumonia. *Decrease RR* - The patient has a **pCO2 of 48 mmHg** and a **pH of 7.3**, indicating **respiratory acidosis** (hypoventilation). - Decreasing the respiratory rate would further exacerbate the acidosis by reducing minute ventilation and increasing pCO2, which is inappropriate.

Question 46: Which of the following statements given below is incorrect regarding CPR?

A. Chest compression rate 100-120/min
B. Depth of chest compression up to 5-6 cm
C. Ventilation 22-25/ min (Correct Answer)
D. Allow adequate chest recoil

Explanation: ***Ventilation 22-25/ min*** - A ventilation rate of 22-25 breaths/min is **too high** for CPR, which typically recommends 10-12 breaths/min, corresponding to 2 breaths after every 30 compressions. - Excessive ventilation can lead to **hyperventilation**, increasing intrathoracic pressure and reducing venous return, thus decreasing cardiac output. *Chest compression rate 100-120/min* - The recommended chest compression rate for adults in CPR is **100-120 compressions per minute**, ensuring adequate blood flow to vital organs. - Maintaining this rate is crucial for maximizing the effectiveness of chest compressions by providing sufficient circulation. *Depth of chest compression up to 5-6 cm* - The recommended depth for adult chest compressions is at least 5 cm (2 inches), but no more than **6 cm (2.4 inches)** to prevent injury. - This depth ensures that enough pressure is exerted to circulate blood effectively without causing excessive trauma. *Allow adequate chest recoil* - Complete chest recoil is essential to allow the heart to **fully refill with blood** between compressions. - Leaning on the chest between compressions prevents adequate recoil, which can reduce pulmonary and coronary perfusion and **decrease the effectiveness of CPR**.

Question 47: In CPR, number of chest compressions per minute in an adult:

A. 30-50 per minute
B. 100-120 per minute (Correct Answer)
C. 50-72 per minute
D. 120-200 per minute

Explanation: ***100-120 per minute*** - The **American Heart Association (AHA)** and other international resuscitation guidelines recommend a compression rate of **100 to 120 beats per minute** for adults. - This rate ensures adequate blood flow to vital organs while minimizing rescuer fatigue. *30-50 per minute* - This rate is **too low** and would be ineffective in maintaining adequate cerebral and coronary perfusion during cardiac arrest. - Insufficient compressions per minute significantly **reduce the chances of survival** and positive neurological outcomes. *50-72 per minute* - While better than 30-50, this rate is still **below the recommended range** for effective CPR in adults. - It would likely result in **inadequate blood flow** to the brain and heart, diminishing the effectiveness of resuscitation. *120-200 per minute* - While aiming for higher compression rates might seem beneficial, rates **above 120 per minute** can be counterproductive. - Excessively fast compressions can **reduce chest recoil** and ventricular filling time, actually decreasing cardiac output and perfusion.

Question 48: A patient in shock requires rapid fluid resuscitation. If intravenous (IV) cannulation is not possible, within what time frame should an intraosseous (IO) line be placed?

A. 2.5 minutes
B. 1 minute
C. 2 minutes
D. 1.5 minutes (Correct Answer)

Explanation: ***1.5 minutes*** - The goal for intraosseous (IO) line placement in a patient in shock when IV access is difficult is within **90 seconds** (1.5 minutes) to ensure rapid fluid resuscitation and drug delivery. - This timeframe is crucial for minimizing the duration of inadequate perfusion and improving patient outcomes in critical situations. *2.5 minutes* - This timeframe is generally considered too long for establishing emergency vascular access in a patient in shock. - Delays beyond **90 seconds** can lead to significant morbidity and mortality due to prolonged hypoperfusion. *1 minute* - While a faster placement time is always desirable, **1 minute** may be a challenging target to consistently achieve, especially for less experienced operators or in difficult situations. - The established guideline aims for a balance between speed and realistic attainability. *2 minutes* - This timeframe is still longer than the recommended maximum for IO access in shock. - Every additional second of delay can negatively impact the patient's condition, making **2 minutes** less ideal than the recommended 1.5 minutes.

Question 49: A 55-year-old woman was admitted to the intensive care unit with severe lobar pneumonia and septic shock. She remained hypoxemic despite intubation, a high fraction of inspired oxygen, and positive end-expiratory pressure (PEEP). When PEEP was increased further, she paradoxically became more hypoxemic and her blood pressure and central venous hemoglobin saturation fell. What would be your approach?

A. Increase PEEP further
B. Keep PEEP at the highest and give adrenaline
C. Increase FiO2
D. Initiate dobutamine and reduce PEEP to 5cm H2O (Correct Answer)

Explanation: ***Initiate dobutamine and reduce PEEP to 5cm H2O*** - The patient is experiencing negative hemodynamic effects from **excessive PEEP**, indicated by falling blood pressure and central venous hemoglobin saturation. Reducing PEEP will improve **venous return** and **cardiac output**. - **Dobutamine** is a positive inotrope that will help support cardiac output and improve oxygen delivery to tissues, addressing the shock state. *Increase PEEP further* - Increasing PEEP would worsen the patient's **hemodynamic compromise** by further increasing intrathoracic pressure, reducing venous return, and potentially decreasing cardiac output, leading to more profound shock. *Keep PEEP at the highest and give adrenaline* - Maintaining high PEEP would continue to suppress cardiac output. While **adrenaline** is a potent vasopressor and inotrope, it would be treating the symptoms (hypotension) without addressing the root cause of the hemodynamic instability (excessive PEEP-induced reduced venous return and cardiac output). *Increase FiO2* - The patient is already on a **high fraction of inspired oxygen** and remains hypoxemic, suggesting that the primary problem is not lack of oxygen in the inspired air but rather impaired oxygen delivery due to hemodynamic compromise or significant intrapulmonary shunting. Increasing FiO2 further is unlikely to resolve the issue and may expose the patient to **oxygen toxicity**.

Question 50: A 22-year-old street vendor was found in the park having a seizure. Cops brought him to ER, unaware of any background medical history. He is continuously having seizures for 13 minutes and paramedics are not able to gain intravenous access. You ensure the airway is secure and administer oxygen, however, you are unable to gain intravenous access after two attempts. Blood glucose levels are 80mg%. Which medication would be most suitable to administer at this stage to treat patient's seizure?

A. Sodium Valproate
B. Lorazepam
C. Midazolam (Correct Answer)
D. Levetiracetam

Explanation: .***Midazolam*** - **Midazolam** is a benzodiazepine that can be given via **intramuscular (IM)**, buccal, or intranasal routes, making it ideal when IV access is difficult or impossible. - Its rapid onset of action and efficacy in acute seizure management, particularly in **status epilepticus**, make it the most appropriate choice in this scenario. *Sodium Valproate* - While an effective anticonvulsant, **sodium valproate** is primarily administered **intravenously** in acute settings, which is not feasible here due to lack of IV access. - It also has a slower onset of action compared to benzodiazepines for immediate seizure cessation. *Lorazepam* - **Lorazepam** is a first-line benzodiazepine for status epilepticus but is typically given **intravenously (IV)**. - Although it can be given IM, its absorption is slower and less predictable than IM midazolam, and the question specifies difficulty in gaining IV access after two attempts. *Levetiracetam* - **Levetiracetam** is an effective anticonvulsant for status epilepticus but is generally administered **intravenously**, requiring reliable IV access. - It works more slowly than benzodiazepines and is often used as a second-line agent or adjunct once immediate seizure control is achieved.

Practice by Chapter

Applied Respiratory Physiology

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Mechanical Ventilation Principles

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Ventilator Management Strategies

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Acute Respiratory Distress Syndrome

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Shock: Classification and Management

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Hemodynamic Monitoring in ICU

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Acid-Base Disorders

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Fluid and Electrolyte Management

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Sedation and Analgesia in ICU

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Neurocritical Care

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Renal Replacement Therapy

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Nutrition in Critical Illness

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