Postoperative Care Practice Questions

Q: What oxygen concentration should be supplemented in all post-operative patients?

30-35%. **Explanation:** In the immediate postoperative period, patients are at high risk for **postoperative hypoxemia** due to several factors: residual effects of anesthetic agents (causing respiratory depression), splinting due to pain, and ventilation-perfusion (V/Q) mismatch caused by atelectasis. **Why 30-35% is the Correct Answer:** Standard practice in the Post-Anesthesia Care Unit (PACU) is to provide supplemental oxygen to maintain an arterial oxygen saturation ($SaO_2$) above 94%. An inspired oxygen concentration ($FiO_2$) of **30-35%** is generally sufficient to prevent hypoxemia in most healthy patients without causing complications. This is typically achieved using a simple face mask (5-6 L/min) or nasal prongs (2-4 L/min). **Analysis of Incorrect Options:** * **A & B (40-60%):** These concentrations are unnecessarily high for routine cases. High $FiO_2$ levels can lead to **absorption atelectasis** (where high oxygen replaces nitrogen in the alveoli, causing them to collapse) and can mask hypoventilation by maintaining saturation despite rising $CO_2$ levels. * **D (20-25%):** Room air is 21%. Providing only 20-25% oxygen offers little to no margin of safety against the physiological shunts and decreased Functional Residual Capacity (FRC) common after surgery. **High-Yield Clinical Pearls for NEET-PG:** * **Diffusion Hypoxia:** Specifically seen after Nitrous Oxide ($N_2O$) use; $N_2O$ rushes out of the blood into the alveoli, diluting oxygen. This is prevented by giving **100% $O_2$ for 5-10 minutes** at the end of surgery. * **Target Saturation:** In patients with COPD or chronic hypercapnia, the target $SaO_2$ is lower (88-92%) to avoid suppressing the hypoxic respiratory drive. * **Most common cause of early post-op hypoxemia:** Atelectasis and decreased FRC.

Q: Peri-operative respiratory failure is most commonly associated with which type?

Type 3. **Explanation:** Respiratory failure is classified into four types based on the underlying pathophysiology. In the peri-operative setting, **Type 3 Respiratory Failure** is the most characteristic and common form. **Why Type 3 is Correct:** Type 3 respiratory failure is specifically defined as **Peri-operative Respiratory Failure**. It is primarily caused by **atelectasis** (collapse of alveoli). During surgery, factors such as general anesthesia, use of muscle relaxants, upper abdominal incisions, and pain lead to a decrease in Functional Residual Capacity (FRC). This causes the small airways to close, especially in dependent lung zones, leading to ventilation-perfusion (V/Q) mismatch and hypoxemia. **Analysis of Incorrect Options:** * **Type 1 (Hypoxemic):** Characterized by $PaO_2 45$ mmHg. It is caused by pump failure (e.g., COPD, neuromuscular disorders, or opioid overdose). * **Type 4 (Shock):** This occurs in patients who are intubated and ventilated during the resuscitation of shock (hypovolemic, septic, or cardiogenic) to reduce the metabolic demand of breathing muscles. **High-Yield Clinical Pearls for NEET-PG:** * **Management of Type 3:** Best managed with incentive spirometry, early mobilization, adequate analgesia (to prevent splinting), and PEEP (Positive End-Expiratory Pressure). * **Risk Factors:** Upper abdominal and thoracic surgeries carry the highest risk due to diaphragmatic dysfunction. * **Key Distinction:** Remember the "Rule of 4": Type 1 (Oxygenation), Type 2 (Ventilation), Type 3 (Atelectasis/Peri-operative), Type 4 (Shock/Hypoperfusion).

Q: Post-anesthetic nausea and vomiting is uncommon with which of the following agents?

Propofol. **Explanation:** **Propofol** is the correct answer because it possesses unique **anti-emetic properties**. Unlike most anesthetic agents, propofol directly modulates the chemoreceptor trigger zone (CTZ) and decreases dopaminergic activity in the area postrema. It is considered the drug of choice for Total Intravenous Anesthesia (TIVA) specifically to reduce the incidence of Postoperative Nausea and Vomiting (PONV). **Analysis of Incorrect Options:** * **Halothane (Option B):** Inhalational agents (volatile anesthetics) are a primary risk factor for PONV. They trigger the vomiting center during the emergence phase of anesthesia. * **Fentanyl & Sufentanil (Options C & D):** These are potent opioids. Opioids are notorious for causing nausea and vomiting by increasing the sensitivity of the vestibular apparatus, delaying gastric emptying, and directly stimulating the CTZ in the medulla. **Clinical Pearls for NEET-PG:** * **Gold Standard for PONV Prophylaxis:** Propofol (TIVA) is the most effective anesthetic strategy to prevent PONV. * **Apfel Score:** A high-yield clinical tool used to predict PONV risk. Key risk factors include: Female gender, non-smoker status, history of motion sickness/PONV, and postoperative opioid use. * **Emetic Potential:** Nitrous oxide ($N_2O$) and Etomidate are also associated with a high incidence of PONV compared to Propofol. * **Management:** The first-line treatment for established PONV often includes 5-HT3 receptor antagonists (e.g., Ondansetron) or Dexamethasone.

Question 1

What oxygen concentration should be supplemented in all post-operative patients?

Accepted Answer

30-35%

Answer

50-60%

Answer

40-45%

Answer

20-25%

Question 2

Peri-operative respiratory failure is most commonly associated with which type?

Accepted Answer

Type 3

Answer

Type 1

Answer

Type 2

Answer

Type 4

Question 3

Which of the following is consistent with return of muscle tone adequate to protect the airway from aspiration after reversal from anesthesia?

Accepted Answer

Five seconds sustained head lift

Answer

TOF ratio of 0.7

Answer

No fade detectable on Double Burst Tetanic Stimulation

Answer

Return of normal resting minute ventilation

Question 4

What is a cause of postoperative hypertension?

Accepted Answer

All of the above

Answer

Pre-operative hypertension

Answer

Inadequate analgesia

Answer

Phaeochromocytoma

Question 5

Post-anesthetic nausea and vomiting is uncommon with which of the following agents?

Accepted Answer

Propofol

Answer

Halothane

Answer

Fentanyl

Answer

Sufentanil

Postoperative Care — MCQs

Postoperative Care — MCQs

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