Critical Care — MCQs

Critical Care Indian Medical PG Practice Questions and MCQs

Question 141: In an ICU setting, patients suffering from which respiratory pathology are at risk of CO2 narcosis?

A. Pneumonia
B. Asthma
C. Emphysema (Correct Answer)
D. Bronchiectasis

Explanation: ***Emphysema*** - Patients with **emphysema** often have chronic **CO2 retention** due to impaired gas exchange and reduced expiratory airflow, making them susceptible to CO2 narcosis with supplemental oxygen [4]. - Their **respiratory drive** is primarily cued by hypoxic stimulation, and increasing oxygen can suppress this drive, leading to further CO2 accumulation [1], [4]. *Pneumonia* - While pneumonia can cause respiratory distress, it typically leads to **hypoxemia** rather than hypercapnia in early stages, as ventilation-perfusion mismatch is the primary issue [3]. - Patients with pneumonia are not inherently predisposed to **CO2 narcosis** unless there is severe underlying lung disease or muscle fatigue. *Asthma* - Acute asthma exacerbations mainly cause **bronchoconstriction** and **air trapping**, leading to hypoxemia. Hypercapnia only occurs in severe, life-threatening asthma with significant respiratory muscle fatigue or impending respiratory failure [2]. - Patients with asthma are generally not at chronic risk of **CO2 narcosis** unless in an acute, severe episode and over-oxygenated. *Bronchiectasis* - Bronchiectasis involves **permanent dilation of bronchi** due to chronic infection and inflammation, leading to impaired mucociliary clearance and recurrent infections. - While it can cause chronic respiratory symptoms and hypoxemia, it typically does not directly lead to **CO2 retention** to the extent seen in advanced COPD, unless there is significant co-existing lung parenchymal damage.

Question 142: Which of the following conditions is MOST likely to lead to obstructive shock?

A. Pericardial tamponade (Correct Answer)
B. Pulmonary embolism
C. Tension pneumothorax
D. None of the options

Explanation: ***Pericardial tamponade*** - **Pericardial tamponade** causes obstructive shock by compressing the heart, leading to impaired ventricular filling and reduced cardiac output. - The accumulation of fluid in the **pericardial sac** prevents the ventricles from adequately expanding during diastole. *Pulmonary embolism* - A **pulmonary embolism** obstructs blood flow from the right ventricle into the pulmonary circulation, increasing afterload and potentially causing right heart failure and reduced cardiac output. - While it can lead to obstructive shock, the direct compression of the heart is not the primary mechanism of obstruction as seen in pericardial tamponade. *Tension pneumothorax* - A **tension pneumothorax** causes obstructive shock by increasing intrathoracic pressure, which compresses the great veins and heart, impairing venous return and cardiac filling. - This condition primarily affects the ability of the heart to fill rather than directly impeding its ejection ability.

Question 143: Which of the following is not included in the APACHE II scoring system?

A. Acute physiology score
B. Age
C. Gender (Correct Answer)
D. Chronic health evaluation

Explanation: ***Gender*** - The **APACHE II (Acute Physiology And Chronic Health Evaluation II)** scoring system does not include gender as a variable. - It focuses on physiological parameters, age, and chronic health status to predict mortality risk in critically ill patients. *Acute physiology score* - The **acute physiology score** is a major component of the APACHE II system, assessing deviations from normal ranges for vital signs and laboratory values. - It includes 12 physiological variables such as heart rate, mean arterial pressure, temperature, and Glasgow Coma Scale (GCS). [1] *Age* - **Age** is an important component of the APACHE II score, as older patients generally have a higher risk of mortality. - Points are assigned based on age categories, with increasing points for older age groups. [1] *Chronic health evaluation* - The chronic health evaluation assesses the presence of significant **pre-existing chronic diseases**, which can impact patient outcomes. - Conditions like cirrhosis, COPD, and immunocompromised states add points to the overall score. [1]

Question 144: 12 yr old Child admitted to ICU with blunt trauma and femur fracture- Pao2 60% despite 100%o2 and rebreather mask, CXR shows lung fields clear but the patient remains confused. What is most likely the diagnosis?

A. Fat embolism syndrome. (Correct Answer)
B. Hypovolaemic shock.
C. Pulmonary embolism.
D. Pulmonary contusion.

Explanation: ***Fat embolism syndrome*** - A **femur fracture** is a classic risk factor for fat embolism syndrome, which causes hypoxemia, neurological dysfunction (confusion), and a normal chest X-ray in its early stages [1]. - The severe **hypoxemia (PaO2 60% despite 100% O2)** that is unresponsive to oxygen therapy is characteristic, along with the patient's altered mental status [1]. *Hypovolaemic shock* - While blunt trauma and a femur fracture can lead to hypovolemic shock, the primary symptoms would be **hypotension** and **tachycardia**, not profound hypoxemia with clear lung fields. - Hypovolemic shock typically causes **generalized tissue hypoperfusion**, not selective neurological symptoms and respiratory failure in the context of a normal chest X-ray. *Pulmonary embolism* - A pulmonary embolism can cause hypoxemia and confusion, but it is less likely immediately after blunt trauma unless there's a predisposing condition, and a **clear chest X-ray** makes it less probable compared to fat embolism syndrome. - Furthermore, the sudden and severe presentation of hypoxemia and neurological changes following a long bone fracture is more characteristic of fat embolism syndrome. *Pulmonary contusion* - Pulmonary contusion would likely be visible on a **chest X-ray** as infiltrates or consolidation and would typically present with symptoms of direct lung injury, such as cough or hemoptysis, which are not mentioned. - While it can cause hypoxemia, a **clear chest X-ray** makes pulmonary contusion an unlikely diagnosis in this scenario.

Question 145: Given the ABG values: pH = 7.24, PO2 = 80, PaCO2 = 36, Na = 131, HCO3 = 14, Cl = 90, BE = -13, Glucose = 135, what does this suggest about the patient's acid-base status?

A. Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis (Correct Answer)
D. Metabolic alkalosis

Explanation: ***Metabolic acidosis*** - The **pH of 7.24** indicates acidosis [2], and the **low HCO3 (14 mEq/L)**, along with a **negative base excess (-13)**, points to a primary metabolic problem [1]. - The PaCO2 (36 mmHg) is within normal limits, suggesting that respiratory compensation is not the primary driver of the acidosis [4]. *Respiratory acidosis* - This would be characterized by a **low pH** with a **high PaCO2**, which is not seen here (PaCO2 is normal at 36 mmHg) [2]. - The primary problem lies in the **bicarbonate level**, not the carbon dioxide level. *Respiratory alkalosis* - This would present with a **high pH** and a **low PaCO2**. - The patient's pH is low (7.24), and the PaCO2 is within normal range, ruling out respiratory alkalosis. *Metabolic alkalosis* - This would be characterized by a **high pH** and a **high HCO3**, which is the opposite of the given values (low pH and low HCO3) [3]. - The base excess would be positive in metabolic alkalosis, not negative.

Question 146: Blood transfusion associated acute lung injury occurs due to -

A. Nosocomial infections
B. Auto-immune disorder
C. Genetic susceptibility
D. HLA-mediated reaction (Correct Answer)

Explanation: ***HLA-mediated reaction*** - Transfusion-related acute lung injury (TRALI) is primarily caused by **antibodies** in the donor plasma (usually anti-HLA or anti-HNA antibodies) reacting with the recipient's **neutrophils** [1]. - This interaction leads to neutrophil activation and sequestration in the pulmonary vasculature, causing **endothelial damage** and increased capillary permeability [1]. *Nosocomial infections* - Nosocomial infections are **hospital-acquired infections** and are not a direct cause of TRALI. - While infections can lead to lung injury, the mechanism of TRALI is distinct and immunologically mediated by donor antibodies. *Auto-immune disorder* - An autoimmune disorder involves the body's immune system attacking its own tissues, which is not the primary mechanism of TRALI. - TRALI is an **alloimmune reaction** where donor antibodies react with host antigens, rather than a pre-existing autoimmune condition. *Genetic susceptibility* - While genetic factors might sometimes play a role in an individual's general inflammatory response or susceptibility to certain conditions, they are **not the direct or primary cause** of TRALI. - The acute lung injury in TRALI is triggered by specific **antibody-antigen interactions** during the transfusion.

Question 147: What is the most common arrhythmia in ICU patients?

A. Atrial flutter
B. Atrial fibrillation (Correct Answer)
C. Atrial Tachycardia
D. Supraventricular Tachycardia

Explanation: ***Atrial fibrillation*** - **Atrial fibrillation (AF)** is the most prevalent arrhythmia in the general population [1], and its incidence is significantly higher in critically ill patients due to various stressors. - Factors like **sepsis**, **hypoxemia**, **electrolyte imbalances**, **myocardial ischemia**, and **inflammatory states** common in the ICU are known triggers for new-onset AF. *Atrial flutter* - While atrial flutter is a common arrhythmia, its overall incidence in the ICU setting is **less frequent than atrial fibrillation**. - It often involves a **re-entrant circuit** in the right atrium [2], leading to characteristic "sawtooth" waves on ECG. *Atrial Tachycardia* - Atrial tachycardia is a form of **supraventricular tachycardia (SVT)** that originates in the atria but is **less common** than AF in the ICU [2]. - It often presents as a **regular, narrow-complex tachycardia** with discrete P waves. *Supraventricular Tachycardia* - This is a broad term encompassing arrhythmias that originate **above the ventricles** [3], including AF, atrial flutter, and atrial tachycardia. - While SVT as a category is common, **atrial fibrillation is the single most frequent specific arrhythmia** within this group in the ICU.

Question 148: Extremities are warm in which type of shock

A. Hypovolemic shock
B. Neurogenic shock (Correct Answer)
C. Anaphylactic shock
D. Cardiogenic shock

Explanation: ***Neurogenic shock*** - This type of shock is caused by a loss of **sympathetic tone**, leading to widespread **vasodilation** and a relative hypovolemia, resulting in warm, flushed extremities. - The decreased systemic vascular resistance causes **blood pooling** in the periphery rather than being shunted to vital organs, contributing to the warm skin. *Hypovolemic shock* - Characterized by **decreased blood volume**, leading to activation of the sympathetic nervous system and **vasoconstriction** to shunt blood to vital organs. - This results in **cold, clammy extremities** due to reduced peripheral perfusion. *Anaphylactic shock* - An acute, life-threatening hypersensitivity reaction involving massive release of inflammatory mediators, causing widespread **vasodilation** and increased vascular permeability. - While it can cause flushing and warmth initially due to vasodilation, it often leads to significant fluid shifts and can present with both warm and then cool, clammy skin as shock progresses. *Cardiogenic shock* - Caused by **severe cardiac pump failure**, leading to decreased cardiac output and poor tissue perfusion. - The body's compensatory mechanisms, including sympathetic activation, cause **peripheral vasoconstriction**, leading to **cold, clammy extremities**.

Question 149: Which of the following statements is false regarding the declaration of brain stem death in a hospital?

A. Presence of neurologist is not required
B. Drug overdose should be ruled out
C. All of the above (Correct Answer)
D. Patient must be in coma

Explanation: ***All of the above*** - This option indicates that all the preceding statements are false. Let's analyze why each individual statement is indeed false in the context of brain stem death declaration [1]. - This implies there is a misunderstanding regarding each aspect of brain stem death criteria, which often requires specific conditions like a neurologist's involvement (though not always strictly mandatory in all protocols), ruling out drug overdose, and the patient being in a coma. *Presence of neurologist is not required* - This statement is false because while it's not universally mandated that a neurologist be one of the two certifying doctors, one of them must be a **senior physician (consultant)** and both must be experienced in brain stem death diagnosis. - In many settings, especially for complex cases or where local protocols specify, a neurologist or neurosurgeon's involvement is highly recommended or required to confirm brain stem death. *Drug overdose should be ruled out* - This statement is false because the absence of drugs that could **mimic brain stem death (e.g., sedatives, muscle relaxants)** is a crucial precondition for testing [3]. - It is essential to ensure that the patient's neurological state is not confounded by reversible causes like drug intoxication before proceeding with brain stem death tests [3]. *Patient must be in coma* - This statement is false because while a patient declared brain stem dead will indeed be in a coma, the criteria for **brain stem death** specifically focus on the irreversible cessation of brainstem function [1], not merely a comatose state [2]. - A coma is a precondition for assessing brain stem death, but the declaration itself requires specific tests demonstrating the absence of **brainstem reflexes** [4] and **apnea** [3], confirming the permanent loss of brainstem activity.

Question 150: Decreased CVP is seen in

A. PEEP
B. Bacterial sepsis (Correct Answer)
C. Heart failure
D. Pneumothorax

Explanation: ***Bacterial sepsis*** - In **sepsis**, widespread **vasodilation** and increased capillary permeability lead to significant fluid redistribution out of the intravascular space [3]. - This results in a decrease in **venous return** and thus a lower **central venous pressure (CVP)** due to relative hypovolemia [2]. *Pneumothorax* - A **pneumothorax** causes increased intrathoracic pressure, compressing the great veins and heart. - This leads to **reduced venous return** and typically an *increase* in CVP, or at least a minimal change, due to obstructed outflow from the right atrium, not a decrease [2]. *PEEP* - **Positive end-expiratory pressure (PEEP)** increases intrathoracic pressure, which impedes venous return to the right atrium [2]. - This elevated pressure can artificially *increase* the measured CVP reading, and it does not typically cause a decrease in intrinsic CVP [2]. *Heart failure* - In **heart failure**, particularly right-sided heart failure or biventricular failure, the heart's pumping efficiency is reduced [1]. - This leads to **venous congestion** and an *increase* in CVP due to fluid overload and the inability of the right ventricle to effectively pump blood forward [2].

Practice by Chapter

Shock Syndromes and Management

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Acute Respiratory Distress Syndrome

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Mechanical Ventilation Principles

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Hemodynamic Monitoring

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Nutrition in Critical Illness

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Sedation and Analgesia in ICU

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Multi-organ Dysfunction Syndrome

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Acid-Base and Electrolyte Disturbances

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Toxicologic Emergencies

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Neurological Emergencies in ICU

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Renal Replacement Therapy

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End-of-Life Care in ICU

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