Critical Care Practice Questions

Q: Brain death is indicated by suppression of all reflexes except which of the following?

Patellar tendon reflex. The diagnosis of brain death requires the irreversible loss of all functions of the entire brain, including the brainstem [3]. The underlying medical concept is that **brain death is a clinical diagnosis** based on the absence of cerebral and brainstem functions, while the **spinal cord may remain intact.** **1. Why the Patellar Tendon Reflex is correct:** The patellar tendon reflex (knee-jerk) is a **monosynaptic spinal reflex**. Its circuit involves the peripheral nerves and the spinal cord segments (L2-L4), bypassing the brain entirely. Since the spinal cord can remain viable even when the brain is dead, spinal reflexes (including deep tendon reflexes, plantar flexion, or the "Lazarus sign") can still be elicited and do not preclude a diagnosis of brain death. **2. Why the other options are incorrect:** * **Oculovestibular reflex (Caloric testing):** This is a brainstem reflex involving the vestibular nuclei (pons/medulla) and the cranial nerves III and VI [1], [2]. Its absence is a mandatory criterion for brain death. * **Corneal reflex:** This reflex tests the integrity of the trigeminal nerve (afferent) and the facial nerve (efferent), mediated through the pons [1], [2]. * **Pharyngeal (Gag) reflex:** This is a lower brainstem reflex involving the glossopharyngeal and vagus nerves (medulla) [1], [2]. **Clinical Pearls for NEET-PG:** * **Prerequisites for Brain Death Testing:** Normothermia (>36°C), systolic BP ≥100 mmHg, and exclusion of drug intoxication or neuromuscular blocking agents [2]. * **The Apnea Test:** This is the definitive clinical test. A positive result (supporting brain death) is a $PCO_2$ >60 mmHg or >20 mmHg above baseline in the absence of respiratory effort [2]. * **Confirmatory Tests (if clinical exam is inconclusive):** Cerebral angiography (gold standard showing "no flow"), EEG (isoelectric/flat), or Transcranial Doppler.

Q: Which of the following is FALSE regarding ARDS?

Hypercapnia. In ARDS (Acute Respiratory Distress Syndrome), the primary pathophysiological hallmark is **Type 1 Respiratory Failure**, which is characterized by profound hypoxemia without an initial increase in $CO_2$ [1]. **Why Hypercapnia is the Correct (False) Statement:** Early and middle stages of ARDS are typically associated with **hypocapnia** (low $PaCO_2$) rather than hypercapnia. This occurs because hypoxemia stimulates the peripheral chemoreceptors, leading to compensatory tachypnea and hyperventilation, which "washes out" carbon dioxide [2]. Hypercapnia is generally a late-stage finding indicating respiratory muscle fatigue or a massive increase in dead space, but it is not a defining or characteristic feature of ARDS itself. **Analysis of Other Options:** * **Hypoxemia:** This is the cardinal feature of ARDS. It results from right-to-left intrapulmonary shunting due to collapsed or fluid-filled alveoli [1]. * **Pulmonary Edema:** ARDS is defined by non-cardiogenic pulmonary edema caused by increased alveolar-capillary permeability (leaky endothelium), leading to protein-rich fluid accumulation in the alveoli [1]. * **Decreased Tidal Volume:** Due to the accumulation of fluid and inflammatory debris, the lungs become stiff (decreased compliance), often referred to as "Baby Lung." This leads to a reduction in effective tidal volume and necessitates a lung-protective ventilation strategy [1]. **NEET-PG High-Yield Pearls:** * **Berlin Criteria:** Acute onset (within 1 week), bilateral opacities on imaging, $PaO_2/FiO_2$ ratio $\leq 300$ mmHg, and edema not fully explained by heart failure [1]. * **Management:** Low tidal volume ventilation (6 mL/kg) is the gold standard to prevent Volutrauma. * **Prone Positioning:** Indicated if $PaO_2/FiO_2 < 150$ to improve V/Q matching.

Q: Which of the following intravenous fluids, if given during resuscitation of cardiac arrest, is most likely to worsen the patient's outcome?

5% Dextrose. Explanation: The correct answer is **5% Dextrose**. During cardiac arrest, the brain undergoes global ischemia. If dextrose-containing fluids are administered, the body cannot metabolize the glucose aerobically due to lack of oxygen. This leads to **anaerobic glycolysis**, resulting in the excessive production of **lactic acid** within the brain tissue (cerebral intracellular acidosis). This acidosis exacerbates neuronal injury, increases the risk of cerebral edema, and significantly worsens neurological outcomes post-resuscitation. Furthermore, hyperglycemia itself is associated with poorer outcomes in critically ill patients. **Analysis of Incorrect Options:** * **Ringer’s Lactate (RL):** This is an isotonic crystalloid and is generally considered a safe fluid for volume expansion during resuscitation, although Normal Saline (0.9% NaCl) is often preferred in the immediate arrest phase. * **Colloids:** While not the first-line choice due to cost and potential renal side effects, they do not cause the specific metabolic neurotoxicity associated with dextrose. * **Whole Blood Transfusion:** While rarely used in the acute "code" setting (unless the arrest is due to hemorrhagic shock), it provides oxygen-carrying capacity and does not inherently worsen neurological outcomes like glucose does. **Clinical Pearls for NEET-PG:** * **Rule of Thumb:** Never use dextrose-containing fluids (D5, D10, DNS) during cardiac arrest or acute stroke unless documented **hypoglycemia** is present. * **Preferred Fluid:** Isotonic crystalloids (Normal Saline or Ringer's Lactate) are the fluids of choice for volume expansion during ACLS [1]. * **Post-Resuscitation Care:** Maintain blood glucose levels between **140–180 mg/dL**; both hypoglycemia and severe hyperglycemia must be avoided to protect the brain.

Q: Acute Lung Injury (ALI) is characterized by all of the following except?

PaO2/FiO2 < 200 mm Hg. The diagnosis of Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrome (ARDS) was historically defined by the **American-European Consensus Conference (AECC)** criteria. [1] This question tests the specific physiological threshold that distinguishes ALI from ARDS. **1. Why Option A is the correct answer:** According to the AECC criteria, the defining difference between ALI and ARDS is the severity of hypoxemia measured by the **PaO2/FiO2 ratio**: * **ALI:** PaO2/FiO2 ratio **≤ 300 mm Hg**. * **ARDS:** PaO2/FiO2 ratio **≤ 200 mm Hg**. Therefore, a ratio < 200 mm Hg characterizes ARDS, not specifically ALI (though ARDS is the most severe form of ALI). **2. Analysis of incorrect options:** * **Option B (Bilateral infiltrates):** Both ALI and ARDS require the presence of bilateral pulmonary infiltrates on frontal chest radiograph, representing non-cardiogenic pulmonary edema. [1] * **Options C & D (PCWP < 18 mm Hg / Normal LA pressure):** A hallmark of ALI/ARDS is that the edema is **non-cardiogenic**. To rule out left heart failure, the Pulmonary Capillary Wedge Pressure (PCWP) must be < 18 mm Hg, or there must be no clinical evidence of elevated Left Atrial (LA) pressure. [1] **Clinical Pearls for NEET-PG:** * **Berlin Definition (2012):** Note that modern clinical practice has replaced the term "ALI" with the Berlin Definition, which categorizes ARDS into **Mild** (P/F 200–300), **Moderate** (P/F 100–200), and **Severe** (P/F < 100). [1] * **Key Trigger:** Sepsis is the most common cause of ARDS. * **Management:** The mainstay of treatment is **Low Tidal Volume Ventilation** (6 mL/kg) to prevent volutrauma.

Question 1

Which of the following drugs is not recommended in septic shock?

Accepted Answer

Rituximab

Answer

Normal saline

Answer

Activated protein C

Answer

Steroids

Question 2

Brain death is indicated by suppression of all reflexes except which of the following?

Accepted Answer

Patellar tendon reflex

Answer

Oculovestibular reflex

Answer

Corneal reflex

Answer

Pharyngeal reflex

Question 3

All are true of septic shock, except?

Accepted Answer

Caused by gram-positive bacteria

Answer

Tachycardia

Answer

Warm skin

Answer

Decreased cardiac output

Question 4

Which of the following is FALSE regarding ARDS?

Accepted Answer

Hypercapnia

Answer

Hypoxemia

Answer

Pulmonary edema

Answer

Decreased tidal volume

Question 5

In gram-negative septicemia, what are the early findings preceding shock?

Accepted Answer

Increased cardiac output, decreased total peripheral resistance

Answer

Increased cardiac output, increased total peripheral resistance

Answer

Increased cardiac output, transient total peripheral resistance

Question 6

Hypovolemic shock is seen in all except?

Accepted Answer

Starvation

Answer

Hemorrhage

Answer

Vomiting

Answer

Diarrhoea

Question 7

Which of the following intravenous fluids, if given during resuscitation of cardiac arrest, is most likely to worsen the patient's outcome?

Accepted Answer

5% Dextrose

Answer

Ringer's lactate

Answer

Colloids

Answer

Whole blood transfusion

Question 8

Synthetic oxygen carrier is made up of which of the following elements?

Accepted Answer

Fluorine

Answer

Iron

Answer

Bronze

Answer

Molybdenum

Question 9

A patient on a ventilator presents with bilateral crepitations in all lung fields. What is the likely finding on chest X-ray?

Accepted Answer

Noncardiogenic pulmonary edema

Answer

Cardiogenic pulmonary edema

Answer

Neurogenic pulmonary edema

Answer

Chemical pneumonitis

Question 10

Acute Lung Injury (ALI) is characterized by all of the following except?

Accepted Answer

PaO2/FiO2 < 200 mm Hg

Answer

Bilateral interstitial infiltrates

Answer

Pulmonary capillary wedge pressure (PCWP) < 18 mm Hg

Answer

Normal Left atrial pressure

Critical Care — MCQs

Critical Care — MCQs

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