Rapid Sequence Induction — MCQs
A case of trauma comes to the emergency. On examination there is evidence of head injury, BP is 90/60 mmHg, and pulse is 150/min. Which of the following anesthetic agent should be used for induction?
During rapid sequence intubation in a child after taking brief history and clinical examination next step is:
Inhalational agent of choice for induction in children is
What is the primary purpose of Sellick's maneuver?
An induction agent of choice for poor-risk patients with cardiorespiratory disease as well as in situations where preservation of a normal blood pressure is crucial:-
An unconscious child is brought to the casualty. What is the correct sequence of the management?
Child with aspiration risk needs emergency surgery. Best induction sequence is:
A 70 kg young athlete was planned for surgery. During anesthesia, vecuronium was not available, so repeated doses of succinylcholine were given intermittently up to 640 mg. During recovery, the patient was not able to spontaneously respire and move limbs. What is the cause?
Stage 2 block (Phase II block) is seen with:
What is the dose of adrenaline given intravenously in a cardiac arrest victim?
Rapid Sequence Induction Indian Medical PG Practice Questions and MCQs
Question 1: A case of trauma comes to the emergency. On examination there is evidence of head injury, BP is 90/60 mmHg, and pulse is 150/min. Which of the following anesthetic agent should be used for induction?
- A. Halothane
- B. Succinylcholine
- C. Thiopentone (Correct Answer)
- D. Ketamine
Explanation: ***Thiopentone*** - It is a **short-acting barbiturate** that causes **rapid unconsciousness** and **reduces cerebral blood flow** and **intracranial pressure (ICP)**, which is beneficial in head injury. - It also has **cardiovascular-depressant effects** that can help manage hypertension, though in this hypotensive patient, careful titration is needed, but its **ICP-lowering effect** is crucial. *Halothane* - Halothane is a **volatile anesthetic** that can cause **dose-dependent myocardial depression** and a **decrease in blood pressure**, which would worsen the patient's existing hypotension. - It also tends to **increase cerebral blood flow**, which is counterproductive in a patient with a head injury and potential increased ICP. *Succinylcholine* - Succinylcholine is a **neuromuscular blocker** used for **rapid sequence intubation**, not as an anesthetic induction agent. - It can cause a **transient increase in ICP** and **hyperkalemia**, both of which can be detrimental in a trauma patient with head injury. *Ketamine* - Ketamine is a dissociative anesthetic that can **increase heart rate** and **blood pressure**, which could be beneficial in a hypotensive patient. - However, it also tends to **increase cerebral blood flow** and **intracranial pressure (ICP)**, making it less ideal for a patient with a head injury.
Question 2: During rapid sequence intubation in a child after taking brief history and clinical examination next step is:
- A. Administer oxygen (Correct Answer)
- B. Analgesic injection with Fentanyl
- C. Preanaesthetic medication with atropine and lignocaine
- D. IV anesthetic Diazepam/Ketamine
Explanation: ***Administer oxygen*** - Pre-oxygenation with 100% oxygen is critical before **rapid sequence intubation (RSI)** to maximize **oxygen reserves** and extend the safe apnea time. - This step helps prevent **hypoxemia** during the intubation procedure, especially in children who have lower functional residual capacity. *Analgesic injection with Fentanyl* - While fentanyl is often used in RSI for its **analgesic** and **sedative properties**, it typically follows pre-oxygenation and is administered as part of the **induction phase**, often concurrently with a paralytic. - Administering fentanyl alone without prior oxygenation or other induction agents would not be the immediate next step in a structured RSI protocol. *Preanaesthetic medication with atropine and lignocaine* - **Atropine** may be used in children to prevent **bradycardia** during intubation, particularly in infants, but it's not the immediate next step after initial assessment; pre-oxygenation is more critical. - **Lidocaine** can be used to blunt the sympathetic response to intubation or to suppress cough, but it's not universally required and comes after pre-oxygenation and other induction medications. *IV anesthetic Diazepam/Ketamine* - **Diazepam** and **ketamine** are **induction agents** that cause sedation and loss of consciousness, but they are administered after pre-oxygenation and often just before the paralytic agent. - Administering an induction agent without adequate pre-oxygenation would increase the risk of **hypoxemia** during the subsequent apnea.
Question 3: Inhalational agent of choice for induction in children is
- A. Halothane
- B. Sevoflurane (Correct Answer)
- C. Desflurane
- D. Isoflurane
Explanation: ***Sevoflurane*** - **Sevoflurane** is the inhalational agent of choice for children due to its **low pungency**, rapid onset, and pleasant odor. - This makes it well-tolerated and suitable for mask induction without causing irritation or breath-holding. *Halothane* - **Halothane** was previously used but is now largely replaced due to its association with **hepatotoxicity** (halothane hepatitis) and cardiac arrhythmias. - While it has a sweet odor, its safety profile is inferior to newer agents. *Desflurane* - **Desflurane** has a very **pungent odor** and is highly irritating to the airway, making it unsuitable for mask induction, especially in children. - It often causes coughing, breath-holding, and laryngospasm during induction if given via a mask. *Isoflurane* - **Isoflurane** also has a **pungent odor** and can cause airway irritation, leading to coughing and breath-holding, making it less ideal for mask inductions in children. - Its slower onset and irritating properties make it less preferred for pediatric induction compared to sevoflurane.
Question 4: What is the primary purpose of Sellick's maneuver?
- A. Prevention of hypertension
- B. Prevention of alveolar collapse
- C. Prevention of aspiration of gastric contents (Correct Answer)
- D. Prevention of bradycardia
Explanation: ***Prevention of aspiration of gastric contents*** - **Sellick's maneuver**, also known as **cricoid pressure**, involves applying pressure to the cricoid cartilage. - This pressure occludes the **esophagus**, thereby preventing the regurgitation and aspiration of gastric contents into the airway, especially during rapid sequence intubation. *Prevention of alveolar collapse* - **Alveolar collapse** (atelectasis) is typically prevented by maintaining positive end-expiratory pressure (PEEP) or using lung recruitment maneuvers during mechanical ventilation. - Sellick's maneuver has no direct role in maintaining **alveolar patency**. *Prevention of hypertension* - **Hypertension** during intubation can be managed with specific medications like opioids or beta-blockers, or by optimizing anesthetic depth. - Sellick's maneuver does not influence **blood pressure regulation**. *Prevention of bradycardia* - **Bradycardia** can occur during intubation due to vagal stimulation and is often managed with anticholinergic drugs like atropine. - Sellick's maneuver does not affect **heart rate** directly.
Question 5: An induction agent of choice for poor-risk patients with cardiorespiratory disease as well as in situations where preservation of a normal blood pressure is crucial:-
- A. Ketamine
- B. Etomidate (Correct Answer)
- C. Propofol
- D. Thiopentone
Explanation: ***Etomidate*** - Etomidate is preferred in patients with **cardiac disease** or **hemodynamic instability** due to its minimal effects on cardiovascular function. - It maintains **cardiovascular stability**, including myocardial contractility and blood pressure, making it ideal for procedures where maintaining a normal blood pressure is crucial. *Ketamine* - Ketamine often causes a **sympathetic stimulating effect**, leading to increases in heart rate and blood pressure, which may be detrimental in such patients. - It is associated with **tachycardia** and **hypertension**, undesirable in a poor-risk patient with cardiorespiratory disease. *Propofol* - Propofol is a potent **vasodilator** and myocardial depressant, which can lead to significant **hypotension**, especially in volume-depleted or critically ill patients. - Its use can result in a dose-dependent decrease in **arterial blood pressure** and **cardiac output**. *Thiopentone* - Thiopentone can cause **myocardial depression** and significant **hypotension**, especially in patients with compromised cardiovascular function. - It leads to a notable decrease in **vascular tone** and venous return, thus lowering blood pressure.
Question 6: An unconscious child is brought to the casualty. What is the correct sequence of the management?
- A. Circulation, Airway, Breathing
- B. Breathing, Circulation, Airway
- C. Circulation, Breathing, Airway
- D. Airway, Breathing, Circulation (Correct Answer)
Explanation: ***Airway, Breathing, Circulation*** - The **ABC sequence** is the cornerstone of pediatric resuscitation as per **PALS (Pediatric Advanced Life Support) guidelines** - In an unconscious child, a patent **airway** is the absolute first priority - without this, no oxygen can reach the lungs regardless of breathing effort - Once airway patency is ensured, **breathing** must be assessed and supported to provide adequate ventilation and oxygenation - Only after securing airway and breathing should **circulation** be addressed, as effective circulation without oxygenation is futile - This sequence prevents **hypoxic brain injury**, which can occur within 4-6 minutes of oxygen deprivation *Circulation, Airway, Breathing* - This violates the fundamental **ABC principle** of emergency management - Prioritizing **circulation** before establishing a patent **airway** means attempting to circulate deoxygenated blood - Without airway patency, any circulatory support will fail to deliver oxygen to vital organs, leading to **irreversible hypoxic damage** - In pediatric emergencies, respiratory failure is more common than primary cardiac arrest, making airway management even more critical *Breathing, Circulation, Airway* - Attempting to support **breathing** before securing the **airway** is physiologically ineffective - An obstructed airway prevents air entry despite breathing efforts or bag-mask ventilation attempts - This sequence can lead to **gastric distension, aspiration**, and worsening hypoxia - Delays in airway management increase the risk of **cardiac arrest** from prolonged hypoxemia *Circulation, Breathing, Airway* - This sequence dangerously delays **airway management**, the most time-critical intervention - In an unconscious child, airway obstruction from tongue falling back or secretions is common and immediately life-threatening - Without a patent airway, neither breathing support nor circulatory measures can prevent **brain death** from anoxia - Following this sequence contradicts all **international resuscitation guidelines** (PALS, AHA, ERC)
Question 7: Child with aspiration risk needs emergency surgery. Best induction sequence is:
- A. Preoxygenation-ketamine-succinylcholine
- B. Sevoflurane-propofol-succinylcholine
- C. Midazolam-propofol-rocuronium
- D. Preoxygenation-propofol-succinylcholine (Correct Answer)
Explanation: ***Preoxygenation-propofol-succinylcholine*** - This sequence describes a **rapid sequence intubation (RSI)**, which is the preferred method for patients at high risk of aspiration, including children needing emergency surgery with an unknown fasting status. - **Preoxygenation** provides an oxygen reserve during the apneic period, **propofol** offers rapid induction with good hemodynamic stability, and **succinylcholine** provides fast-onset, short-acting neuromuscular blockade, crucial for preventing aspiration. *Preoxygenation-ketamine-succinylcholine* - While preoxygenation and succinylcholine are appropriate for RSI, **ketamine** may not be the optimal choice for a child with aspiration risk due to its potential to increase secretions and maintain laryngeal reflexes, which could complicate intubation. - Ketamine can also cause **emergence delirium** in some children, making it less favorable for a smooth anesthetic course compared to propofol. *Sevoflurane-propofol-succinylcholine* - **Sevoflurane** is an inhaled anesthetic often used for mask induction in children due to its non-pungent odor and rapid onset. However, it is generally **not suitable for RSI** in patients with aspiration risk as it has a slower induction time compared to intravenous agents and can cause coughing or laryngospasm. - Using both sevoflurane and propofol for induction in an RSI scenario is redundant and prolongs the induction phase, increasing aspiration risk. *Midazolam-propofol-rocuronium* - **Midazolam** is a benzodiazepine used for anxiolysis and sedation but has a **slower onset** and longer duration of action compared to propofol for rapid induction. - **Rocuronium** is a non-depolarizing neuromuscular blocker with a slower onset of action than succinylcholine, making it less ideal for RSI where immediate paralysis for intubation is critical to prevent aspiration.
Question 8: A 70 kg young athlete was planned for surgery. During anesthesia, vecuronium was not available, so repeated doses of succinylcholine were given intermittently up to 640 mg. During recovery, the patient was not able to spontaneously respire and move limbs. What is the cause?
- A. Phase II blockade (Correct Answer)
- B. Muscle weakness due to repeated fasciculations
- C. Undiagnosed muscular dystrophy
- D. Pseudocholinesterase deficiency
Explanation: **Phase II blockade** - Prolonged administration of **succinylcholine** (> 30-60 minutes or high cumulative doses) can lead to a shift from Phase I to **Phase II block**. - In Phase II block, the neuromuscular junction exhibits characteristics similar to a **nondepolarizing block**, including fade on train-of-four stimulation and post-tetanic potentiation, leading to prolonged paralysis. *Muscle weakness due to repeated fasciculations* - While succinylcholine initially causes **fasciculations** due to depolarization, prolonged paralysis is not directly explained by muscle weakness from repeated fasciculations alone. - Fasciculations are a transient early effect and do not account for the sustained paralysis seen with high-dose, repeated administration. *Undiagnosed muscular dystrophy* - While certain **neuromuscular disorders** can alter response to muscle relaxants, there is no information in the scenario to suggest pre-existing muscular dystrophy. - Administering a large amount of succinylcholine accounts for the prolonged paralysis without needing to invoke an undiagnosed condition. *Pseudocholinesterase deficiency* - A deficiency in **pseudocholinesterase** would lead to a prolonged initial Phase I block with a typical dose of succinylcholine due to impaired metabolism. - However, the scenario describes **repeated doses** adding up to a very high cumulative amount (640 mg), pushing the patient into a Phase II block even if pseudocholinesterase levels were normal.
Question 9: Stage 2 block (Phase II block) is seen with:
- A. Isoflurane
- B. Enflurane
- C. Suxamethonium (Correct Answer)
- D. Sevoflurane
Explanation: ***Suxamethonium*** - **Suxamethonium** (succinylcholine) is a depolarizing neuromuscular blocker that can cause a **Phase II block** with prolonged or high-dose administration. - Phase II block, also known as **desensitization block**, clinically resembles a non-depolarizing block and can be antagonized by **anticholinesterases**. *Isoflurane* - **Isoflurane** is an inhaled anesthetic that causes muscle relaxation by enhancing the effects of non-depolarizing neuromuscular blockers, but does not directly induce a Phase II block. - It primarily acts on GABA receptors in the CNS to produce anesthesia and has minimal direct effect on **nicotinic acetylcholine receptors** at the neuromuscular junction. *Enflurane* - **Enflurane** is another inhaled anesthetic that, similar to isoflurane, potentiates neuromuscular blockade but does not directly cause a **Phase II block**. - Its effects are primarily on the **central nervous system**, contributing to anesthesia and muscle relaxation through central mechanisms. *Sevoflurane* - **Sevoflurane** is a commonly used inhaled anesthetic that also enhances the effects of neuromuscular blockers but does not cause a unique **Phase II block** itself. - Like other volatile anesthetics, it facilitates muscle relaxation, thereby reducing the dose of neuromuscular blockers required.
Question 10: What is the dose of adrenaline given intravenously in a cardiac arrest victim?
- A. 10 ml of 1 in 10,000 solution (Correct Answer)
- B. 1 ml of 1 in 10,000 solution
- C. 2 ml of 1 in 1000 solution
- D. 10 ml of 1 in 1000 solution
Explanation: **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.
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