Fast induction and recovery is seen in?
Which of the following is NOT a contraindication for spinal anaesthesia?
In which context can helium replace nitrogen as a diluent gas in oxygen mixtures?
Which of the following cannot be given by epidural anaesthesia?
What is the most reliable indicator to prevent esophageal intubation?
Stages of anesthesia were established by
Ayre's T-piece is which type of circuit
What is a significant disadvantage of ketamine?
Which of the following local anesthetics has the highest maximum concentration allowed for epidural block?
The inducing agent of choice in shock -
NEET-PG 2012 - Anesthesiology NEET-PG Practice Questions and MCQs
Question 11: Fast induction and recovery is seen in?
- A. N2O (Correct Answer)
- B. Methoxyflurane
- C. Ether
- D. Halothane
Explanation: ***N2O*** - **Nitrous oxide (N2O)** has a very **low blood-gas partition coefficient**, meaning it rapidly equilibrates between the alveolar gas and blood. - This rapid equilibration leads to a **fast onset of anesthetic action** (induction) and quick elimination from the body (recovery). *methoxyflurane* - **Methoxyflurane** has a **high blood-gas partition coefficient**, which means it has high solubility in blood. - This high solubility leads to **slow induction and prolonged recovery** as more anesthetic needs to be dissolved and then eliminated from the blood. *ether* - **Diethyl ether** also has a relatively **high blood-gas partition coefficient**, resulting in slow induction and recovery. - Its high solubility in blood and tissues means it takes longer to achieve and then dissipate its anesthetic effect. *halothane* - **Halothane** has a **moderate blood-gas partition coefficient**, leading to a slower induction and recovery compared to N2O. - While faster than methoxyflurane or ether, its solubility is still significant enough to delay its onset and offset.
Question 12: Which of the following is NOT a contraindication for spinal anaesthesia?
- A. Raised intracranial tension
- B. Bleeding disorder
- C. Hypertension (Correct Answer)
- D. Infection at injection site
Explanation: ***Hypertension*** - While **severe uncontrolled hypertension** may necessitate blood pressure stabilization before surgery, **mild to moderate hypertension** is not an absolute contraindication for spinal anesthesia. - In fact, spinal anesthesia can sometimes be beneficial in hypertensive patients due to its **vasodilatory effects**, which may help lower blood pressure. *Bleeding disorder* - A **bleeding disorder** (e.g., thrombocytopenia, coagulopathy) is a **major contraindication** due to the high risk of **epidural or spinal hematoma** formation. - A hematoma can lead to **spinal cord compression** and irreversible neurological damage. *Raised intracranial tension* - **Raised intracranial tension (ICT)** is a **strict contraindication** because the drop in cerebrospinal fluid (CSF) pressure during spinal anesthesia can worsen the pressure gradient across the foramen magnum. - This can precipitate **herniation of the brainstem** and lead to catastrophic neurological injury or death. *Infection at injection site* - The presence of an **infection at the injection site** is an absolute contraindication as it poses a significant risk of introducing bacteria into the **subarachnoid space**. - This can lead to serious complications such as **meningitis** or a **spinal abscess**.
Question 13: In which context can helium replace nitrogen as a diluent gas in oxygen mixtures?
- A. Argon
- B. Xenon
- C. Helium
- D. None of the options (Correct Answer)
Explanation: **None of the options** - This question implies that helium might replace *another noble gas* as a diluent, but the correct application is for helium to replace **nitrogen** in oxygen mixtures, particularly in **diving applications**. This question likely has a flaw in its premise if expecting one of the noble gases listed to be the 'replacement' for nitrogen, as helium *is* the replacement. - Helium is used instead of nitrogen in diving gases (**trimix, heliox**) for deep dives because it is less narcotic than nitrogen under pressure, reducing the risk of **nitrogen narcosis**. *Argon* - **Argon** is denser than nitrogen and has a higher narcotic potential at depth, making it unsuitable as a replacement for nitrogen in diving gases. - It is sometimes used during **dry suit inflation** for insulation due to its low thermal conductivity, but not as a breathing gas diluent. *Xenon* - **Xenon** is a potent anesthetic agent, even at atmospheric pressure, due to its high lipid solubility. - Its use as a diluent would cause severe **narcosis** and render a diver unconscious, making it entirely inappropriate for diving mixtures. *Helium* - While helium is indeed the gas that replaces nitrogen as a diluent in oxygen mixtures for deep diving, it being listed as an option here suggests a misunderstanding of the question's phrasing. The question is asking for **in which context** helium can replace nitrogen, not asking to identify helium itself as the replacement. - Given the other options are noble gases that *cannot* replace nitrogen in this context, "None of the options" is the most accurate answer if the question implies picking from the provided list for a replacement *for helium* or a suitable *alternative* to helium, which isn't the case here.
Question 14: Which of the following cannot be given by epidural anaesthesia?
- A. Morphine
- B. Remifentanil (Correct Answer)
- C. Alfentanil
- D. Fentanyl
Explanation: ***Remifentanil*** - **Remifentanil** is specifically designed for **intravenous administration** and is rapidly metabolized by plasma esterases, making it unsuitable for epidural use. - Due to its short half-life and rapid metabolism, epidural administration would provide inconsistent and fleeting analgesia, and its breakdown products are not inert in the epidural space, potentially causing **neurotoxicity**. *Morphine* - **Morphine** is a commonly used opioid for **epidural analgesia** due to its hydrophilicity, allowing for prolonged action in the cerebrospinal fluid. - It provides effective **postoperative pain relief** and has a relatively slow onset but long duration of action when administered epidurally. *Alfentanil* - **Alfentanil** is a synthetic opioid that has been used for **epidural analgesia**, though less commonly than fentanyl or sufentanil, sometimes in conjunction with local anesthetics. - It has a faster onset and shorter duration of action compared to morphine, but still provides effective **analgesia** when administered epidurally. *Fentanyl* - **Fentanyl** is a widely used lipophilic opioid for **epidural analgesia**, often combined with local anesthetics, for both surgical and obstetric pain. - Its lipophilicity allows for rapid absorption and a relatively quick onset of action, providing effective **segmental analgesia**.
Question 15: What is the most reliable indicator to prevent esophageal intubation?
- A. Oxygen saturation on pulse oximeter
- B. Direct visualization of passing tube beneath vocal cords
- C. Auscultation over chest
- D. Measurement of CO2 in exhaled air (EtCO2). (Correct Answer)
Explanation: ***Measurement of CO2 in exhaled air (EtCO2)*** - The presence of **carbon dioxide** in exhaled air confirms tracheal intubation as the esophagus does not contain CO2. - This method provides a **real-time**, objective assessment of tube placement that is highly reliable because even small amounts of CO2 are detected. *Oxygen saturation on pulse oximeter* - This indicator measures **oxygenation**, which can remain adequate for several minutes after esophageal intubation due to pre-oxygenation. - A **delayed drop in saturation** might indicate esophageal intubation, but it's not immediate and therefore not the most reliable early indicator. *Direct visualization of passing tube beneath vocal cords* - While helpful, **direct visualization** can sometimes be misleading due to difficult airways or poor visibility, where the tube might appear to pass correctly but enter the esophagus. - This method is **operator-dependent** and its reliability can vary based on the intubator's experience and the patient's anatomy. *Auscultation over chest* - **Auscultation** can detect breath sounds; however, sounds can be transmitted from the stomach or surrounding tissues, leading to false positives. - It is also very difficult to reliably distinguish between **esophageal and tracheal sounds**, especially in noisy environments or with inexperienced personnel, making it less reliable than EtCO2.
Question 16: Stages of anesthesia were established by
- A. Diethyl ether (Correct Answer)
- B. Nitrous oxide
- C. Halothane
- D. Chloroform
Explanation: ***Diethyl ether** - The classic stages of anesthesia (analgesia, excitement, surgical anesthesia, medullary depression) were originally described in relation to the administration of **diethyl ether**. - Its slow onset and prolonged half-life allowed for the clear observation and definition of these distinct stages. *Nitrous oxide* - This gaseous anesthetic has a rapid onset and offset, making it difficult to clearly delineate all four classical stages with its use. - It is often used as an adjunct to other anesthetics rather than as a sole agent for prolonged surgical anesthesia. *Halothane* - Halothane is a potent volatile anesthetic that became popular after ether, but its use also does not typically involve the clear, step-wise progression through all four anesthetic stages as seen with ether. - It was one of the first widely used inhaled anesthetics that largely replaced ether due to better patient control and fewer side effects. *Chloroform* - Chloroform was another early anesthetic but was associated with significant cardiac and hepatic toxicity, leading to its limited use and eventual discontinuation. - While it induced anesthesia, the clear staging of anesthetic depth was primarily established and standardized using diethyl ether.
Question 17: Ayre's T-piece is which type of circuit
- A. Type A
- B. Type B
- C. Type E (Correct Answer)
- D. Type D
Explanation: ***Type E*** - The **Ayre's T-piece** is classified as a **Type E breathing circuit** according to the classification of Mapleson circuits. - It is a modification of the Mapleson A circuit, widely used in pediatric anesthesia due to its high efficiency and low resistance. *Type A* - **Mapleson A circuits** have the fresh gas flow (FGF) inlet near the patient and a reservoir bag at the circuit's most distal end. - While very efficient for spontaneous ventilation, they are not the same as an Ayre's T-piece. *Type B* - **Mapleson B circuits** have the fresh gas flow inlet and the reservoir bag near the patient, with the expiratory valve further away. - This configuration is generally inefficient for both spontaneous and controlled ventilation. *Type D* - **Mapleson D circuits** have the fresh gas flow inlet near the patient and the expiratory valve close to the reservoir bag, which is distal to the patient. - These circuits are commonly used for controlled ventilation, but are not the Ayre's T-piece.
Question 18: What is a significant disadvantage of ketamine?
- A. Increased heart rate
- B. Increased ICT
- C. Delirium (Correct Answer)
- D. All of the options
Explanation: ***Delirium*** - Ketamine is known to cause **emergence phenomena**, which include **vivid dreams, hallucinations**, and **delirium**, particularly during recovery from anesthesia. - This psychotomimetic effect can be distressing for patients and may necessitate the co-administration of a **benzodiazepine** to mitigate these symptoms. *Increased heart rate* - While ketamine does cause an **increase in heart rate** and **blood pressure** due to sympathetic stimulation, this is often considered a disadvantage but not the *most significant* when compared to the unique cognitive side effects. - This effect can be beneficial in patients with **hemodynamic instability**, but can be problematic in those with **cardiovascular disease**. *Increased ICT* - It is often considered a contraindication in patients with **elevated intracranial pressure (ICP)** as it can potentially increase **cerebral blood flow** and thus ICP. - However, recent studies suggest that in adequately ventilated patients, the effect on ICP may be less pronounced than previously thought, making delirium a more consistent and prominent disadvantage for many patients. *All of the options* - While ketamine can cause an **increased heart rate** and potentially affect **intracranial pressure**, **delirium** and other emergence phenomena are often highlighted as a unique and significant disadvantage because they are highly distressing and difficult to manage. - The psychotomimetic effects are a hallmark side effect that often governs its cautious use without concurrent medication.
Question 19: Which of the following local anesthetics has the highest maximum concentration allowed for epidural block?
- A. Chlorprocaine (Correct Answer)
- B. Lidocaine
- C. Ropivacaine
- D. Bupivacaine
Explanation: ***Chlorprocaine*** - **Chlorprocaine** is an ester-type local anesthetic that can be safely used in higher concentrations for epidural blocks up to **3%**, due to its rapid hydrolysis by plasma pseudocholinesterase, leading to a very short half-life and reduced systemic toxicity. - Its rapid metabolism minimizes the risk of accumulation and systemic toxicity, making it a suitable choice when a dense block is needed and a short duration of action is acceptable. *Lidocaine* - **Lidocaine** is an amide-type local anesthetic commonly used in epidural blocks, but its maximum concentration for this application is typically limited to **2%** to avoid systemic toxicity. - Higher concentrations of lidocaine are associated with an increased risk of neurological and cardiovascular adverse effects. *Ropivacaine* - **Ropivacaine** is an amide-type local anesthetic that is less cardiotoxic than bupivacaine, with common concentrations for epidural use ranging from **0.2% to 1%**. - Its maximum concentration is significantly lower than chlorprocaine due to its longer duration of action and potential for systemic toxicity at higher doses. *Bupivacaine* - **Bupivacaine** is a potent amide-type local anesthetic with a high risk of cardiotoxicity, and its maximum concentration for epidural use is generally restricted to **0.5%** or even less for continuous infusions. - Using concentrations above this limit significantly increases the risk of severe cardiovascular complications, including arrhythmias and cardiac arrest.
Question 20: The inducing agent of choice in shock -
- A. Isoflurane
- B. Ketamine (Correct Answer)
- C. Desflurane
- D. Thiopentone
Explanation: **Ketamine** * **Ketamine** is preferred in shock due to its sympathomimetic properties, which maintain or increase blood pressure and heart rate, thus preserving **cardiovascular stability**. * It also has minimal respiratory depression and bronchodilatory effects, making it safer for patients with compromised respiratory function. * The cardiovascular stimulating effects of ketamine helps maintain haemodynamic stability in shocked patients. It maintains cerebral autoregulation and perfusion of vital organs. *Isoflurane* * **Isoflurane** is an inhaled anesthetic that typically causes **dose-dependent myocardial depression** and **vasodilation**, which can worsen hypotension in a shock state. * It can significantly decrease systemic vascular resistance, thereby exacerbating the already compromised cardiovascular status of a shock patient. *Desflurane* * **Desflurane** is an inhaled anesthetic known for its rapid onset and offset but can cause a **significant increase in heart rate and blood pressure** upon rapid concentration changes, which may be detrimental in an unstable patient. * Like isoflurane, it also causes dose-dependent peripheral vasodilation and myocardial depression, which can worsen hypotension in patients in shock. *Thiopentone* * **Thiopentone** is a barbiturate that causes significant **myocardial depression** and **peripheral vasodilation**, leading to a substantial drop in blood pressure. * Its use in shock would further compromise cardiovascular stability and is generally contraindicated due to its potent hemodynamic depressant effects.