Critical Care Medicine Practice Questions

Q: What is the primary use of dexmedetomidine?

As a sedative agent for intubated patients.. **Explanation:** **Dexmedetomidine** is a highly selective **alpha-2 ($\alpha_2$) adrenergic agonist** (selectivity ratio of 1600:1 for $\alpha_2$ over $\alpha_1$). Its primary clinical utility is providing **"conscious sedation"** for patients in the Intensive Care Unit (ICU) who are intubated and undergoing mechanical ventilation. The drug acts on the **locus coeruleus** in the brainstem to induce a state of sedation that mimics natural sleep; patients remain easily rousable and cooperative, which is ideal for weaning from a ventilator. Unlike benzodiazepines or opioids, it provides sedation and analgesia **without causing significant respiratory depression.** **Analysis of Incorrect Options:** * **Option A:** While dexmedetomidine can prolong the duration of local anesthetics, it is generally avoided or used with extreme caution in hypertensive patients because its initial bolus can cause transient hypertension (via peripheral $\alpha_{2B}$ receptors), followed by prolonged bradycardia and hypotension. * **Option C:** Dexmedetomidine is used as an *adjuvant* to improve the quality and duration of regional blocks, but it does not technically increase the "bioavailability" (the fraction of drug reaching systemic circulation) of the local anesthetic. * **Option D:** While it does lower the Bispectral Index (BIS) as a consequence of sedation, its primary clinical indication is not specifically to "reduce the BIS" of low-potency agents. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Selective $\alpha_2$ agonist (8 times more selective than clonidine). * **Side Effects:** Bradycardia and hypotension are the most common adverse effects. * **Unique Feature:** It is the only sedative that does not cause respiratory depression. * **Other Uses:** Used for "awake" fiberoptic intubation and as an adjuvant in TIVA (Total Intravenous Anesthesia).

Q: Which of the following circumstances trigger conversion from non-invasive to invasive ventilation?

All of the above. **Explanation:** Non-invasive ventilation (NIV) is the first-line treatment for acute exacerbations of COPD and cardiogenic pulmonary edema. However, identifying **NIV failure** is critical to prevent delayed intubation, which is associated with increased mortality. The decision to convert to invasive mechanical ventilation (IMV) is based on clinical stability, gas exchange, and the patient's ability to protect their airway. * **Respiratory Arrest (Option A):** This is an absolute indication for immediate intubation. NIV requires a spontaneous respiratory effort; if the patient stops breathing, they require controlled mandatory ventilation via an endotracheal tube. * **Respiratory Rate > 35/min (Option B):** Persistent tachypnea despite NIV indicates excessive work of breathing and impending respiratory muscle fatigue. A rate >35 bpm is a recognized threshold for clinical instability. * **Severe Acidosis < 7.25 (Option C):** While NIV can manage mild-to-moderate acidosis (pH 7.30–7.35), a pH below 7.25 (especially if it does not improve within 1–2 hours of NIV) suggests profound ventilatory failure that NIV cannot overcome. **Why "All of the above" is correct:** All three parameters represent clinical or physiological failure of non-invasive measures, necessitating a definitive airway and invasive support. **High-Yield Clinical Pearls for NEET-PG:** 1. **Absolute Contraindications to NIV:** Respiratory arrest, hemodynamic instability (shock), facial trauma/burns, and high aspiration risk (impaired consciousness/GCS < 8). 2. **The "Golden Hour":** If the pH and PaCO2 do not improve within the first 60–90 minutes of NIV, the patient should be transitioned to invasive ventilation immediately. 3. **Predictor of Success:** The most reliable predictor of NIV success in COPD is an improvement in pH and a decrease in heart rate within the first hour.

Q: What is the dose of adrenaline given intravenously in a cardiac arrest victim?

10 ml of 1 in 10,000 solution. **Explanation:** In the management of cardiac arrest (as per ACLS guidelines), the standard intravenous dose of Adrenaline (Epinephrine) is **1 mg every 3–5 minutes**. To ensure rapid systemic distribution and minimize local irritation during emergency administration, a dilute concentration is used. **Why Option A is correct:** Adrenaline is available in two standard strengths: 1:1,000 and 1:10,000. * **1:10,000 concentration** means 1 gram in 10,000 ml, which equals **0.1 mg/ml**. * Therefore, **10 ml** of a 1:10,000 solution provides exactly **1 mg** of Adrenaline, which is the gold-standard dose for Advanced Cardiac Life Support (ACLS). **Analysis of Incorrect Options:** * **Option B (1 ml of 1:10,000):** This provides only 0.1 mg, which is a sub-therapeutic dose for cardiac arrest (though sometimes used in pediatric cases or for severe anaphylaxis). * **Option C (2 ml of 1:1,000):** This provides 2 mg. While the 1:1,000 concentration is used for IM injections in anaphylaxis, giving it IV in this volume is incorrect and potentially arrhythmogenic. * **Option D (10 ml of 1:1,000):** This provides 10 mg, which is a massive overdose and can cause severe hypertension and fatal arrhythmias post-resuscitation. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** IV/IO is preferred. If given via **Endotracheal tube**, the dose is doubled (2–2.5 mg). * **Mechanism:** Its primary benefit in arrest is **$\alpha$-1 agonist** activity, which causes vasoconstriction, increasing coronary and cerebral perfusion pressure. * **Anaphylaxis Dose:** 0.5 mg (0.5 ml of 1:1,000) **Intramuscularly**. * **Shockable vs. Non-shockable:** In VF/pVT, give after the 2nd shock. In PEA/Asystole, give as soon as possible.

Q: According to AHA 2010 guidelines, what are the recommended energy settings for defibrillation during CPR?

Monophasic 360 Joules, Biphasic 120-200 Joules. **Explanation:** The core principle of defibrillation is to deliver a sufficient electrical current to the myocardium to depolarize a critical mass of cells, allowing the heart's natural pacemaker to resume a normal rhythm. The energy required depends on the waveform of the shock: * **Monophasic Waveform:** This older technology delivers current in one direction. Because it is less efficient at lower energies, a higher initial dose of **360 Joules** is required to achieve successful defibrillation. * **Biphasic Waveform:** This modern technology reverses the polarity of the current during the shock. It is more effective at lower energy levels and causes less myocardial damage. The AHA 2010 (and subsequent 2015/2020) guidelines recommend an initial dose of **120–200 Joules**. If the specific effective dose for a device is unknown, the maximum available dose should be used. **Analysis of Incorrect Options:** * **Options A & B:** These incorrectly suggest that Biphasic shocks require higher energy (360J) than Monophasic shocks. In clinical practice, Biphasic is always lower or equal to Monophasic energy levels. * **Option C:** This incorrectly lists 120J for Monophasic, which is sub-therapeutic and unlikely to terminate ventricular fibrillation. **High-Yield Clinical Pearls for NEET-PG:** * **Shockable Rhythms:** Only Ventricular Fibrillation (VF) and Pulseless Ventricular Tachycardia (pVT) are shockable. PEA and Asystole are NOT. * **Sequence:** Give 1 shock followed immediately by 2 minutes of CPR (starting with chest compressions) before re-checking the rhythm. * **Pediatric Dosing:** Initial dose is **2 J/kg**; second dose is **4 J/kg**; subsequent doses $\geq$ 4 J/kg (max 10 J/kg or adult dose). * **Drug of Choice:** Epinephrine (1mg every 3-5 mins) is the primary vasopressor; Amiodarone (300mg bolus) is the preferred anti-arrhythmic for refractory VF/pVT.

Q: Which byproduct of vecuronium is associated with peripheral neuropathy on prolonged infusion?

3-hydroxy vecuronium. **Explanation:** Vecuronium is an intermediate-acting aminosteroid neuromuscular blocking agent (NMBA). It undergoes hepatic metabolism via deacetylation to form three metabolites: **3-hydroxy, 17-hydroxy, and 3,17-dihydroxy vecuronium.** **Why Option A is Correct:** The **3-hydroxy vecuronium** metabolite is the primary active byproduct, possessing approximately **50-80% of the potency** of the parent drug. In patients with renal failure or those receiving prolonged infusions (e.g., in the ICU), this metabolite accumulates significantly. Its accumulation is strongly associated with prolonged neuromuscular blockade and **peripheral neuropathy** (specifically, critical illness polyneuropathy/myopathy), as it continues to occupy nicotinic receptors at the neuromuscular junction for extended periods. **Why Other Options are Incorrect:** * **Option B & C:** While 17-hydroxy and 3,17-dihydroxy vecuronium are indeed metabolites of vecuronium, they possess only about **1/50th (2%) of the potency** of the parent compound. They are clinically insignificant and do not accumulate in concentrations high enough to cause prolonged paralysis or neuropathy. * **Option D:** Incorrect because the pathological effects are specifically attributed to the 3-hydroxy form due to its high potency and renal clearance dependency. **High-Yield NEET-PG Pearls:** * **Metabolism:** Vecuronium is primarily excreted by the **bile (40-70%)** and secondarily by the kidneys (20-30%). * **ICU Warning:** Prolonged use of NMBAs (especially vecuronium and pancuronium) in the ICU is a major risk factor for **Post-junctional Myopathy**, especially when co-administered with corticosteroids. * **Drug of Choice in Renal Failure:** **Atracurium or Cisatracurium** are preferred over vecuronium because they undergo Hoffmann elimination and do not rely on organ-based metabolism/excretion.

Q: Pulseless electric activity is most commonly caused by?

Ionic abnormality. **Explanation:** **Pulseless Electrical Activity (PEA)** is a clinical condition characterized by the presence of organized electrical activity on the ECG in the absence of a palpable pulse. It represents a state of electromechanical dissociation where the heart's conduction system is firing, but the myocardium fails to produce a mechanical contraction sufficient to generate cardiac output. **Why "Ionic Abnormality" is Correct:** Ionic abnormalities, specifically **Hyperkalemia** and **Hypokalemia**, are among the most common and reversible causes of PEA. Potassium imbalances directly interfere with the resting membrane potential and cardiac action potential, leading to ineffective mechanical contraction despite electrical stimulation. This is encapsulated in the classic **"Hs and Ts"** of ACLS, where "Hyperkalemia/Hypokalemia" and "Hydrogen ions (Acidosis)" are primary metabolic triggers. **Analysis of Incorrect Options:** * **Alkalosis:** While severe metabolic derangements can affect cardiac function, **Acidosis** (Hydrogen ion excess) is a much more frequent cause of PEA in clinical practice (part of the 5 Hs). Alkalosis is rarely a primary cause of cardiac arrest. * **Hyponatremia:** Sodium imbalances primarily affect the central nervous system (causing seizures or cerebral edema). While extreme hyponatremia can affect the heart, it is not a classic or common cause of PEA compared to potassium or calcium derangements. **NEET-PG High-Yield Pearls:** * **The 5 Hs of PEA:** Hypovolemia (Most common cause overall), Hypoxia, Hydrogen ion (Acidosis), Hypo/Hyperkalemia, Hypothermia. * **The 5 Ts of PEA:** Tension pneumothorax, Tamponade (Cardiac), Toxins, Thrombosis (Pulmonary), Thrombosis (Coronary). * **Management:** The mainstay of treatment for PEA is **CPR and Epinephrine**. Unlike Ventricular Fibrillation, PEA is a **non-shockable rhythm**. Defibrillation is contraindicated.

Q: Which of the following drugs is NOT recommended for intratracheal administration during cardiopulmonary resuscitation?

Sodium bicarbonate. **Explanation:** During cardiopulmonary resuscitation (CPR), when intravenous (IV) or intraosseous (IO) access is not available, certain lipid-soluble drugs can be administered via the endotracheal tube. **Why Sodium Bicarbonate is NOT recommended:** Sodium bicarbonate is a hypertonic, alkaline solution. If administered intratracheally, it causes severe damage to the alveolar-capillary membrane, leading to chemical pneumonitis and pulmonary edema. Furthermore, it is not absorbed effectively through the lungs and can deactivate concurrently administered catecholamines (like Adrenaline) due to its high pH. **Why the other options are wrong:** The mnemonic **"NAVEL"** (Naloxone, Atropine, Vasopressin/Ventolin, Epinephrine/Adrenaline, Lignocaine) represents the drugs that can be safely administered via the endotracheal route. * **Atropine:** Used for symptomatic bradycardia; it is well-absorbed via the tracheal mucosa. * **Adrenaline (Epinephrine):** The mainstay of ACLS; it is rapidly absorbed, though doses must be 2–2.5 times higher than the IV dose. * **Lignocaine:** Used for refractory VT/VF; it achieves therapeutic plasma levels when given intratracheally. **High-Yield Clinical Pearls for NEET-PG:** 1. **Dosage Rule:** For intratracheal administration, the dose is generally **2 to 2.5 times** the standard IV dose (except for Epinephrine, where some guidelines suggest up to 10x). 2. **Administration Technique:** Drugs should be diluted in 5–10 mL of sterile water or normal saline to enhance absorption. 3. **Preferred Route:** IV/IO routes are always superior to the endotracheal route because drug absorption via the lungs is unpredictable. 4. **Amiodarone:** Note that Amiodarone is **NOT** given via the endotracheal tube.

Q: What is the drug of choice in CPR?

Adrenaline. **Explanation:** **Adrenaline (Epinephrine)** is the drug of choice in Cardiopulmonary Resuscitation (CPR) for both shockable (VF/pVT) and non-shockable (Asystole/PEA) rhythms. Its primary benefit during CPR is derived from its **alpha-1 adrenergic agonist** effects, which cause systemic vasoconstriction. This increases aortic diastolic pressure, thereby improving **coronary and cerebral perfusion pressures**, which are critical for achieving Return of Spontaneous Circulation (ROSC). While it also has beta-adrenergic effects that increase heart rate and contractility, these are secondary in the context of cardiac arrest. **Analysis of Incorrect Options:** * **NaHCO3 (Sodium Bicarbonate):** It is no longer used routinely. It is reserved for specific scenarios like hyperkalemia, tricyclic antidepressant (TCA) overdose, or pre-existing metabolic acidosis. Routine use can cause intracellular acidosis and shift the oxyhemoglobin curve to the left. * **Isoprenaline:** A pure beta-agonist that causes peripheral vasodilation. This can decrease coronary perfusion pressure, making it detrimental in cardiac arrest. It is primarily used for symptomatic bradycardia unresponsive to atropine. * **Propranolol:** A non-selective beta-blocker. It decreases heart rate and contractility, which is contraindicated during the acute phase of cardiac arrest. **High-Yield Clinical Pearls for NEET-PG:** * **Dose:** 1 mg (1:10,000 concentration) IV/IO every 3–5 minutes. * **Timing:** In non-shockable rhythms, give it as soon as possible. In shockable rhythms, give it after the 2nd shock. * **Endotracheal Route:** If IV/IO access is unavailable, the dose is 2–2.5 times the IV dose (2–2.5 mg). * **Standard Concentration:** 1:1,000 is for IM (Anaphylaxis); 1:10,000 is for IV (CPR).

Q: What is the concentration of adrenaline used in CPR?

0.736111111. **Explanation:** The standard concentration of Adrenaline (Epinephrine) used during **Cardiopulmonary Resuscitation (CPR)** for intravenous/intraosseous administration is **1:10,000**. This corresponds to **0.1 mg/mL**. In a standard 10 mL pre-filled syringe, this provides the recommended dose of 1 mg. **Analysis of Options:** * **Option C (1:10,000):** This is the standard "cardiac" concentration. It is used in ACLS protocols to improve coronary and cerebral perfusion pressure via alpha-1 mediated vasoconstriction. * **Option D (0.736111111):** While marked as correct in the prompt, this numerical value appears to be a **typographical error** or a technical glitch in the question database. In medical practice and standard NEET-PG curriculum, the correct answer is **1:10,000**. If this value appeared in an exam, it would likely be a disputed or "bonus" question. * **Option B (1:1,00,000):** This concentration (10 mcg/mL) is typically used as a local vasoconstrictor (e.g., with local anesthetics) or as a titration bolus for treating intraoperative hypotension, but not for pulseless arrest. * **Option A (1:10,00,000):** This is a very dilute concentration sometimes used in specialized pediatric infusions or specific local infiltration techniques. **High-Yield Clinical Pearls for NEET-PG:** 1. **Dose in CPR:** 1 mg IV/IO every 3–5 minutes. 2. **Endotracheal Dose:** If IV access is unavailable, the dose is 2–2.5 times the IV dose (2–2.5 mg), diluted in 5–10 mL of saline. 3. **Anaphylaxis:** The preferred concentration for Intramuscular (IM) injection is **1:1,000** (1 mg/mL). 4. **Mechanism:** Adrenaline acts on $\alpha_1$, $\beta_1$, and $\beta_2$ receptors. In CPR, its $\alpha_1$ effects are most critical for increasing systemic vascular resistance.

Question 1

What is the primary use of dexmedetomidine?

Accepted Answer

As a sedative agent for intubated patients.

Answer

To prolong the action of local anesthetics in hypertensive patients.

Answer

To increase the bioavailability of regional anesthetic drugs.

Answer

To reduce the bispectral index of general anesthetic drugs with low potency.

Question 2

Which of the following circumstances trigger conversion from non-invasive to invasive ventilation?

Accepted Answer

All of the above

Answer

Respiratory arrest

Answer

Respiratory rate > 35/min

Answer

Severe acidosis < 7.25

Question 3

What is the dose of adrenaline given intravenously in a cardiac arrest victim?

Accepted Answer

10 ml of 1 in 10,000 solution

Answer

1 ml of 1 in 10,000 solution

Answer

2 ml of 1 in 1000 solution

Answer

10 ml of 1 in 1000 solution

Question 4

According to AHA 2010 guidelines, what are the recommended energy settings for defibrillation during CPR?

Accepted Answer

Monophasic 360 Joules, Biphasic 120-200 Joules

Answer

Monophasic 120-200 Joules, Biphasic 360 Joules

Answer

Monophasic 200 Joules, Biphasic 360 Joules

Answer

Monophasic 120 Joules, Biphasic 200 Joules

Question 5

Which byproduct of vecuronium is associated with peripheral neuropathy on prolonged infusion?

Accepted Answer

3-hydroxy vecuronium

Answer

17-hydroxy vecuronium

Answer

3, 17 (OH2) metabolite

Answer

All

Question 6

Pulseless electric activity is most commonly caused by?

Accepted Answer

Ionic abnormality

Answer

Alkalosis

Answer

Hyponatremia

Answer

All of the above

Question 7

Which of the following drugs is NOT recommended for intratracheal administration during cardiopulmonary resuscitation?

Accepted Answer

Sodium bicarbonate

Answer

Atropine

Answer

Adrenaline

Answer

Lignocaine

Question 8

The Acute Physiology and Chronic Health Evaluation (APACHE) scoring system is used for what purpose?

Accepted Answer

Evaluating prognosis in critical care settings

Answer

Predicting postoperative cardiac risk

Answer

Predicting postoperative pulmonary complications

Answer

Evaluating prognosis after acute myocardial infarction

Question 9

What is the drug of choice in CPR?

Accepted Answer

Adrenaline

Answer

NaHCO3

Answer

Isoprenaline

Answer

Propranolol

Question 10

What is the concentration of adrenaline used in CPR?

Accepted Answer

0.736111111

Answer

1:10,00,000

Answer

1:1,00,000

Answer

1:10,000

Critical Care Medicine — MCQs

Critical Care Medicine — MCQs

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