Postoperative Nausea and Vomiting — MCQs
Postoperative nausea and vomiting are uncommon with
Which of the following is the primary neurotransmitter involved in nausea and vomiting associated with chemotherapy?
A woman must vomit whenever she eats spicy food. Arrange the sequence of events during vomiting. 1. LES is open and UES is closed 2. Strong contractions in the stomach 3. Inspiration against a closed glottis 4. Relaxation of the pyloric sphincter 5. LES opens and UES opens 6. Reverse peristalsis in the small intestine LES: Lower esophageal sphincter UES: Upper esophageal sphincter
The most common type of perioperative shock is
How do 5-HT3 receptor antagonists like ondansetron work to prevent nausea and vomiting?
Which of the following is not a risk factor for postoperative pulmonary complication?
A 56-year-old woman has nausea due to chemotherapy for breast cancer. Droperidol is effective in reducing nausea because it blocks which of the following?
Which Benzodiazepine decreases post-operative nausea & vomiting:-
All of the following drugs increase the risk of postoperative nausea and vomiting after squint surgery in children except?
Which of the following intravenous anaesthetic agent causes decrease in postoperative nausea and vomiting :
Postoperative Nausea and Vomiting Indian Medical PG Practice Questions and MCQs
Question 1: Postoperative nausea and vomiting are uncommon with
- A. Propofol (Correct Answer)
- B. Etomidate
- C. Thiopentone
- D. All of the options
Explanation: ***Propofol*** - **Propofol** is known for its antiemetic properties, which contributes to a lower incidence of **postoperative nausea and vomiting (PONV)**. - Its mechanism involves modulating **dopaminergic activity** in the chemoreceptor trigger zone and possibly direct effects on serotonin receptors. *Etomidate* - While etomidate is a fast-acting induction agent, it does not inherently possess antiemetic properties. - Its use does not significantly reduce the risk of **PONV** compared to other induction agents, and some studies suggest it may even increase the risk slightly. *Thiopentone* - **Thiopentone**, a barbiturate, is typically associated with a higher incidence of **PONV** compared to propofol. - It does not offer any protective effect against nausea and vomiting and can contribute to these side effects in the postoperative period. *All of the options* - This option is incorrect because **etomidate** and **thiopentone** do not share the **antiemetic properties** of propofol. - Only **propofol** is specifically known to reduce the incidence of **PONV**.
Question 2: Which of the following is the primary neurotransmitter involved in nausea and vomiting associated with chemotherapy?
- A. Dopamine
- B. Acetylcholine
- C. GABA
- D. Serotonin (Correct Answer)
Explanation: ***Serotonin*** - **Serotonin (5-HT)**, particularly acting on **5-HT3 receptors**, is a major neurotransmitter mediating chemotherapy-induced nausea and vomiting (CINV). - Chemotherapeutic agents can damage **enterochromaffin cells** in the gastrointestinal tract, leading to the release of serotonin, which then stimulates vagal afferents and the **chemoreceptor trigger zone (CTZ)**. *Dopamine* - **Dopamine (D2 receptors)** plays a role in nausea and vomiting, particularly in the **chemoreceptor trigger zone (CTZ)**. - While dopamine antagonists can be used as antiemetics, **serotonin** is considered the primary neurotransmitter in CINV due to the direct impact of chemotherapy on serotonin release. *Acetylcholine* - **Acetylcholine** is involved in motion sickness and is targeted by **anticholinergic antiemetics (e.g., scopolamine)**. - Its primary role in CINV is less significant compared to serotonin, which has a more direct link to the mechanisms of chemotherapy. *GABA* - **GABA (gamma-aminobutyric acid)** is the main inhibitory neurotransmitter in the brain and can reduce anxiety and modulate vomiting. - While **benzodiazepines**, which enhance GABAergic activity, are used as adjuncts in CINV to reduce **anticipatory nausea** and anxiety, GABA itself is not the primary mediator of the emetic response to chemotherapy.
Question 3: A woman must vomit whenever she eats spicy food. Arrange the sequence of events during vomiting. 1. LES is open and UES is closed 2. Strong contractions in the stomach 3. Inspiration against a closed glottis 4. Relaxation of the pyloric sphincter 5. LES opens and UES opens 6. Reverse peristalsis in the small intestine LES: Lower esophageal sphincter UES: Upper esophageal sphincter
- A. 4,6,2,1,3,5
- B. 4,6,2,5,3,1
- C. 6,4,2,5,1,3
- D. 6,4,2,3,1,5 (Correct Answer)
Explanation: ***6,4,2,3,1,5*** - The correct sequence of vomiting begins with **reverse peristalsis in the small intestine (6)**, which propels intestinal contents retrograde toward the stomach. - The **pyloric sphincter then relaxes (4)**, allowing duodenal contents to enter the stomach and mix with gastric contents. - **Strong stomach contractions (2)** follow, building initial pressure within the gastric lumen. - **Deep inspiration against a closed glottis (3)** is critical—this generates high intra-abdominal and intrathoracic pressure (the essential expulsive force). - The **LES opens while UES remains closed (1)**, allowing gastric contents to move into the esophagus. - Finally, the **UES opens (5)**, permitting expulsion of contents through the mouth. *4,6,2,1,3,5* - Incorrect because **pyloric sphincter relaxation precedes reverse peristalsis**, which is physiologically backwards—intestinal contents must first move toward the stomach before the pylorus can allow them entry. - The positioning of glottis closure late in the sequence misrepresents when intra-abdominal pressure is generated. *4,6,2,5,3,1* - This sequence incorrectly places **both sphincters opening (5) before the critical pressure-generating step (3)**, which would result in premature expulsion without adequate force. - The inspiration against closed glottis must occur before final sphincter opening to create the necessary expulsive pressure. *6,4,2,5,1,3* - This option misorders the final events by having **both sphincters open (5) before adequate pressure generation (3)** and before the sequential LES opening (1). - The glottis closure step is positioned too late—it must precede sphincter opening to generate the high intra-abdominal pressure required for forceful expulsion.
Question 4: The most common type of perioperative shock is
- A. Hypovolemic shock (Correct Answer)
- B. Septic shock
- C. Cardiogenic shock
- D. Neurogenic shock
Explanation: ***Hypovolemic shock*** - This is the most common type of shock encountered in the **perioperative period** due to potential **blood loss** during surgery or fluid shifts. - **Inadequate circulating blood volume** leads to reduced tissue perfusion and oxygen delivery. *Septic shock* - Caused by a severe systemic response to an **infection**, leading to widespread inflammation and vasodilation. - While possible post-operatively, it is not the most common type of shock immediately associated with the surgical procedure itself. *Cardiogenic shock* - Occurs due to **primary cardiac dysfunction**, such as a massive myocardial infarction or severe heart failure, leading to insufficient cardiac output. - Though some patients may have pre-existing cardiac conditions, it is not the most frequent cause of shock following surgery. *Neurogenic shock* - Results from severe injury to the **central nervous system**, typically spinal cord injury, leading to loss of sympathetic tone and profound vasodilation. - This is a less common cause of perioperative shock unless directly related to spinal surgery or severe trauma.
Question 5: How do 5-HT3 receptor antagonists like ondansetron work to prevent nausea and vomiting?
- A. Blocking serotonin receptors in the chemoreceptor trigger zone (Correct Answer)
- B. Inhibiting dopamine release
- C. Decreasing gastric acid secretion
- D. Reducing gastrointestinal motility
Explanation: ***Blocking serotonin receptors in the chemoreceptor trigger zone*** - 5-HT3 receptor antagonists like **ondansetron** work primarily by blocking **serotonin (5-HT3) receptors** found in the **chemoreceptor trigger zone (CTZ)** and on afferent vagal nerves in the gastrointestinal tract. - This action prevents serotonin, a key mediator of nausea and vomiting, from stimulating these receptors and initiating the **emetic reflex**. *Inhibiting dopamine release* - **Dopamine antagonists**, such as metoclopramide or prochlorperazine, act by blocking **D2 dopamine receptors** in the CTZ, which is a different mechanism of action. - While dopamine can contribute to nausea and vomiting, 5-HT3 antagonists do not directly work by inhibiting dopamine release. *Decreasing gastric acid secretion* - Medications that decrease gastric acid secretion, such as **proton pump inhibitors (PPIs)** or **H2 blockers**, are used to treat conditions like GERD or ulcers. - This mechanism is not directly involved in the antiemetic action of 5-HT3 receptor antagonists. *Reducing gastrointestinal motility* - Some antiemetics, like **anticholinergics (e.g., scopolamine)**, can reduce gastrointestinal motility, which may help alleviate nausea. - However, 5-HT3 receptor antagonists primarily exert their antiemetic effect through receptor blockade rather than by significantly altering GI motility.
Question 6: Which of the following is not a risk factor for postoperative pulmonary complication?
- A. Normal BMI (18.5-24.9) (Correct Answer)
- B. Age 25-40 years
- C. Upper abdominal surgery
- D. Patient with 20 pack years of smoking
Explanation: ***Patient with 20 pack years of smoking*** - This is a significant risk factor for postoperative pulmonary complications, as **chronic smoking** impairs lung function and mucociliary clearance. - Patients with a history of **20 pack-years or more** are at a substantially increased risk of developing atelectasis, pneumonia, and respiratory failure after surgery. *Normal BMI (18.5-24.9)* - A **normal BMI** is not considered a risk factor for postoperative pulmonary complications; instead, it is associated with a lower risk compared to obesity or underweight states. - Patients with a normal BMI generally have **better respiratory mechanics** and lung volumes, reducing their susceptibility to pulmonary issues. *Age 25-40 years* - This age range is generally associated with a **lower risk** of postoperative pulmonary complications compared to very young or elderly patients. - Younger adults typically have **better physiological reserves** and healthier lungs, contributing to a reduced incidence of respiratory problems post-surgery. *Upper abdominal surgery* - **Upper abdominal surgery** is a significant risk factor for postoperative pulmonary complications due to its proximity to the diaphragm. - It often leads to **diaphragmatic dysfunction**, reduced lung volumes, and increased pain, all of which predispose patients to atelectasis and pneumonia.
Question 7: A 56-year-old woman has nausea due to chemotherapy for breast cancer. Droperidol is effective in reducing nausea because it blocks which of the following?
- A. Glucocorticoid receptors in the vomiting center
- B. Dopamine receptors in the CTZ (Correct Answer)
- C. ACh receptors in the periphery
- D. 5-HT3 receptors in the CTZ
Explanation: **Dopamine receptors in the CTZ** - Droperidol is a **butyrophenone antipsychotic** that acts as an **antidopaminergic agent**, primarily targeting **D2 dopamine receptors**. - Its antiemetic effect is mainly due to blocking these **dopamine receptors in the chemoreceptor trigger zone (CTZ)**, which is involved in initiating the vomiting reflex. *Glucocorticoid receptors in the vomiting center* - **Glucocorticoids** like dexamethasone are used as antiemetics, but they act via **glucocorticoid receptors**, not through dopamine receptor blockade. - Their mechanism involves inhibiting prostaglandin synthesis and inflammation, reducing the release of serotonin. *ACh receptors in the periphery* - Drugs that block **acetylcholine (ACh) receptors** (e.g., scopolamine) are used for motion sickness, but they are not the primary mechanism of action for droperidol. - **Anticholinergics** typically exert their effects on the vestibular system and peripheral muscarinic receptors. *5-HT 2 receptors in the CTZ* - While some antiemetics (e.g., **ondansetron**) block **serotonin (5-HT3) receptors**, droperidol's primary action is not on **5-HT2 receptors**. - **Serotonin antagonists** are particularly effective for chemotherapy-induced nausea and vomiting as chemotherapy often releases serotonin from enterochromaffin cells.
Question 8: Which Benzodiazepine decreases post-operative nausea & vomiting:-
- A. Midazolam (Correct Answer)
- B. Diazepam
- C. Lorazepam
- D. All of the options
Explanation: ***Midazolam*** - **Midazolam** is a commonly used benzodiazepine in anesthesia that has been shown to have **antiemetic properties** and can decrease the incidence of **postoperative nausea and vomiting (PONV)**. - Its mechanism may involve its sedative and anxiolytic effects, indirectly reducing the triggers for nausea. *Diazepam* - While **diazepam** is a benzodiazepine with sedative and anxiolytic effects, it is not primarily known for reducing PONV. - Its longer duration of action compared to midazolam can also contribute to unwanted **postoperative sedation**. *Lorazepam* - **Lorazepam** is another benzodiazepine used for anxiolysis and sedation but is not a primary agent for the prevention of PONV. - Like diazepam, its prolonged effects can lead to **delayed recovery** and drowsiness, which may not be desirable in the postoperative period. *All of the options* - While all listed drugs are benzodiazepines, only **midazolam** is consistently recognized and utilized for its ability to reduce PONV in the perioperative setting. - The other benzodiazepines do not demonstrate the same consistent benefit in PONV reduction and may have other side effects that limit their utility for this specific purpose.
Question 9: All of the following drugs increase the risk of postoperative nausea and vomiting after squint surgery in children except?
- A. Halothane
- B. Propofol (Correct Answer)
- C. Nitrous Oxide
- D. Opioids
Explanation: ***Propofol*** - Propofol is known to have **antiemetic properties** and is often used to reduce the incidence of postoperative nausea and vomiting (PONV). - Its mechanism involves modulating **GABA-A receptors** and potentially other pathways that suppress emetic responses. *Halothane* - **Inhalational anesthetics** like halothane are a significant risk factor for PONV, particularly in children and following surgeries like squint repair. - They tend to increase PONV by directly stimulating the **chemoreceptor trigger zone** and altering gut motility. *Opioids* - Opioids, commonly used for postoperative pain control, are a well-known cause of **nausea and vomiting**. - They activate **opioid receptors** in the chemoreceptor trigger zone and the gastrointestinal tract, leading to emesis and delayed gastric emptying. *Nitrous Oxide* - The use of **nitrous oxide** as part of a general anesthetic regimen has been consistently associated with an increased risk of PONV. - It is believed to contribute to PONV by increasing the risk of **bowel distension** and stimulating neurotransmitter release involved in emesis.
Question 10: Which of the following intravenous anaesthetic agent causes decrease in postoperative nausea and vomiting :
- A. Propofol (Correct Answer)
- B. Etomidate
- C. Ketamine
- D. Thiopentone
Explanation: ***Propofol*** - **Propofol** has antiemetic properties, which contributes to a reduced incidence of **postoperative nausea and vomiting (PONV)**. - Its mechanism of action in reducing PONV is thought to involve effects on **dopaminergic receptors** and **serotonin pathways** in the brain. *Etomidate* - **Etomidate** is not known to significantly reduce PONV and may even have a neutral effect or slightly increase it compared to propofol. - Its primary advantages include **cardiovascular stability**, which is unrelated to antiemetic effects. *Ketamine* - **Ketamine** is associated with a higher incidence of PONV, especially at higher doses, due to its **psychedelic side effects** and stimulation of the chemoreceptor trigger zone. - It is known for causing **emergence delirium** and does not possess antiemetic properties. *Thiopentone* - **Thiopentone** (Thiopental) does not have any significant antiemetic properties and is not typically used for its effect on PONV. - It was historically used as an induction agent but has largely been replaced by newer drugs like propofol.
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