Preoperative Evaluation and Management — MCQs

Preoperative Evaluation and Management Indian Medical PG Practice Questions and MCQs

Question 51: Which of the following drugs are commonly used in pre-anaesthetic medication?

A. Diazepam
B. Scopolamine
C. Morphine
D. All of the above (Correct Answer)

Explanation: **Explanation:** Pre-anaesthetic medication refers to the administration of drugs prior to anesthesia to allay anxiety, provide sedation, induce amnesia, and minimize the side effects of anesthetic agents. * **Diazepam (Benzodiazepine):** It is primarily used for its **anxiolytic and sedative** properties. It also provides anterograde amnesia, which helps in reducing the patient’s psychological trauma associated with the surgical environment. * **Scopolamine (Anticholinergic/Antimuscarinic):** Also known as Hyoscine, it is used to **reduce salivary and bronchial secretions** (antisialogogue effect). It is particularly valued in pre-medication for its potent **amnestic and sedative** effects compared to atropine, and it helps prevent vagal bradycardia. * **Morphine (Opioid):** It is used to provide **pre-operative analgesia**, especially in patients with pre-existing pain or those undergoing painful procedures (e.g., regional blocks). It also contributes to sedation and reduces the dose requirement of induction agents. Since all three drugs serve specific, essential roles in preparing a patient for surgery, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Glycopyrrolate** is often preferred over Atropine/Scopolamine as an antisialogogue because it does not cross the blood-brain barrier (no CNS side effects). * **Midazolam** is the most common benzodiazepine used today due to its shorter half-life and superior water solubility. * **H2 Blockers (Ranitidine) or Proton Pump Inhibitors (Pantoprazole)** are often added to pre-medication to reduce gastric volume and acidity (Mendelson’s Syndrome prophylaxis). * **Clonidine/Dexmedetomidine (α2 agonists)** are increasingly used to provide sedation and blunt the sympathetic response to intubation.

Question 52: Which of the following is NOT contained in Ringer's lactate solution?

A. Sodium
B. Potassium
C. Chloride
D. Bicarbonate (Correct Answer)

Explanation: **Explanation:** Ringer’s Lactate (RL), also known as Hartmann’s solution, is a balanced salt solution used for fluid resuscitation. The correct answer is **Bicarbonate** because RL does not contain pre-formed bicarbonate. Instead, it contains **Sodium Lactate**. Once infused, the lactate is metabolized by the liver into bicarbonate, providing a buffering effect against metabolic acidosis. **Breakdown of Options:** * **Sodium (A):** RL contains approximately **130 mEq/L** of Sodium. This is slightly hyponatremic compared to plasma (135–145 mEq/L). * **Potassium (B):** RL contains **4 mEq/L** of Potassium, which mimics physiological plasma levels. * **Chloride (C):** RL contains **109 mEq/L** of Chloride. This is lower than Normal Saline (154 mEq/L), making RL less likely to cause hyperchloremic metabolic acidosis. * **Bicarbonate (D):** Bicarbonate is unstable in plastic bags and can precipitate with calcium. Therefore, lactate is used as a stable precursor. **High-Yield Clinical Pearls for NEET-PG:** 1. **Composition:** Na⁺ (130), Cl⁻ (109), Lactate (28), K⁺ (4), and **Calcium (3)**. 2. **Osmolarity:** RL is slightly **hypotonic** (273 mOsm/L) compared to plasma (285–295 mOsm/L). 3. **Contraindications:** * Avoid in **Traumatic Brain Injury (TBI)** due to hypotonicity (may increase cerebral edema). * Do not co-administer with **blood transfusions** in the same line; the Calcium in RL can bind with the Citrate anticoagulant in blood, leading to clot formation. * Use with caution in severe liver failure (impaired lactate metabolism).

Question 53: Plasma expanders are primarily indicated in which of the following conditions?

A. Severe anemia
B. Severe trauma (Correct Answer)
C. Pulmonary edema
D. Cardiac failure

Explanation: ### Explanation **Correct Answer: B. Severe trauma** **1. Why Severe Trauma is Correct:** Plasma expanders (colloids or crystalloids) are primarily indicated for **acute hypovolemia** to restore intravascular volume and maintain tissue perfusion. In severe trauma, patients often suffer from acute hemorrhage or fluid loss, leading to hypovolemic shock. Plasma expanders increase the oncotic pressure (in the case of colloids) or provide rapid volume replacement (crystalloids), thereby stabilizing hemodynamics and preventing multi-organ failure. **2. Why Other Options are Incorrect:** * **A. Severe Anemia:** The primary deficit here is oxygen-carrying capacity (hemoglobin), not necessarily intravascular volume. The treatment of choice is **Packed Red Blood Cell (PRBC) transfusion**, not plasma expanders, which would further dilute the remaining hemoglobin. * **C. Pulmonary Edema:** This condition is characterized by fluid overload in the lungs. Administering plasma expanders would worsen the hydrostatic pressure and exacerbate the edema. Management involves **diuretics** and fluid restriction. * **D. Cardiac Failure:** In heart failure, the pump is failing, and the patient is often in a state of fluid overload (congestive heart failure). Adding volume with plasma expanders increases preload, which can lead to acute decompensation. **3. High-Yield Clinical Pearls for NEET-PG:** * **Ideal Plasma Expander:** Should be iso-oncotic with plasma, have a long half-life, be non-pyrogenic, and not interfere with blood grouping/cross-matching. * **Dextran Warning:** Dextran-40/70 can interfere with blood cross-matching and may cause acute renal failure or coagulopathy. * **Hydroxyethyl Starch (HES):** Its use is now restricted in critically ill patients due to the risk of renal injury and increased mortality. * **Gelatins:** These have the shortest duration of action among colloids and carry a higher risk of anaphylactoid reactions.

Question 54: Which of the following is contraindicated in renal failure?

A. Pancuronium
B. Pethidine
C. Enflurane
D. Midazolam (Correct Answer)

Explanation: In the context of renal failure, drugs that have active metabolites or primary renal excretion are generally avoided or used with extreme caution. **Why Midazolam is the Correct Answer:** Midazolam is primarily metabolized by the liver into **1-hydroxymidazolam**. In patients with normal renal function, this metabolite is quickly conjugated and excreted. However, in renal failure, 1-hydroxymidazolam and its glucuronide conjugate accumulate. These metabolites possess significant pharmacological activity, leading to **prolonged sedation, delayed emergence, and respiratory depression**. While not "absolute" in all clinical settings, it is considered the most problematic among the options provided for routine use in renal failure. **Analysis of Other Options:** * **Pancuronium:** This is a long-acting neuromuscular blocker that is **80% excreted unchanged by the kidneys**. It is contraindicated in renal failure because it leads to prolonged paralysis. (Note: In many clinical scenarios, both Pancuronium and Midazolam are avoided, but Midazolam's metabolic accumulation is a frequent focus for sedation-related questions). * **Pethidine (Meperidine):** It is metabolized to **normeperidine**, which is excreted renally. Accumulation of normeperidine is highly toxic and can cause **seizures**. It is generally contraindicated in renal failure. * **Enflurane:** It undergoes metabolism to inorganic fluoride ions, which are nephrotoxic. While it is avoided in patients with pre-existing renal disease, it is less commonly used today compared to Sevoflurane or Isoflurane. **NEET-PG High-Yield Pearls:** 1. **Muscle Relaxant of Choice:** **Atracurium or Cisatracurium** (due to Hoffman elimination, which is independent of renal/hepatic function). 2. **Induction Agent of Choice:** **Propofol** or **Etomidate**. 3. **Opioid of Choice:** **Fentanyl** or **Remifentanil** (no active metabolites). 4. **Avoid:** Morphine (accumulation of Morphine-6-glucuronide causes respiratory depression).

Question 55: A patient has an ASA score of 3. What does this score indicate regarding their systemic disease and activity limitations?

A. Mild systemic disease with no limitation of activity.
B. Severe systemic disease that limits activity but is not incapacitating. (Correct Answer)
C. Moribund state with an expected survival of less than 24 hours, even with surgery.
D. Incapacitating systemic disease that poses a threat to life.

Explanation: The **ASA Physical Status Classification System** is a standardized tool used by anesthesiologists to assess a patient's preoperative physical condition and predict perioperative risk. ### **Explanation of the Correct Answer** **ASA Class 3** is defined as a patient with **severe systemic disease** that results in **functional limitations** (i.e., it limits their activity) but is **not incapacitating**. * **Clinical Examples:** Poorly controlled diabetes or hypertension, COPD, morbid obesity (BMI ≥40), history (>3 months) of MI, CVA, TIA, or CAD/stents, stable angina, or end-stage renal disease (ESRD) undergoing regular dialysis. ### **Analysis of Incorrect Options** * **Option A (ASA 2):** Describes mild systemic disease without substantive functional limitations (e.g., well-controlled HTN, mild obesity, or a smoker). * **Option D (ASA 4):** Describes severe systemic disease that is a **constant threat to life** and is incapacitating (e.g., recent <3 months MI/CVA, ongoing cardiac ischemia, or severe valve dysfunction). * **Option C (ASA 5):** Describes a **moribund** patient who is not expected to survive without the operation (e.g., ruptured abdominal aneurysm, massive trauma). ### **High-Yield Clinical Pearls for NEET-PG** * **ASA 1:** A normal, healthy, non-smoking patient with minimal/no alcohol use. * **ASA 6:** A declared brain-dead patient whose organs are being removed for donor purposes. * **The "E" Suffix:** If the surgery is an emergency, the letter 'E' is added to the classification (e.g., ASA 3E). This significantly increases the predicted perioperative mortality compared to the same class in elective cases. * **Pregnancy:** A healthy pregnancy is automatically classified as **ASA 2**.

Question 56: In patients with liver disease, what is the preferred anesthetic agent?

A. Halothane
B. Ether
C. Isoflurane (Correct Answer)
D. None of the above

Explanation: **Explanation:** The primary goal in managing anesthesia for patients with liver disease is to maintain **hepatic blood flow** and **oxygen delivery** while avoiding agents that undergo extensive hepatic metabolism. **Why Isoflurane is the Correct Answer:** Isoflurane is considered the volatile anesthetic of choice for patients with liver dysfunction due to two main reasons: 1. **Minimal Metabolism:** Only about **0.2%** of isoflurane is metabolized by the liver, the lowest among older volatile agents. This minimizes the risk of metabolite-induced hepatotoxicity. 2. **Preservation of Hepatic Blood Flow:** Unlike other agents, isoflurane maintains the **Hepatic Arterial Buffer Response (HABR)**. It causes less reduction in hepatic blood flow and may even increase it by causing vasodilation of the hepatic artery, ensuring adequate oxygen delivery to hepatocytes. **Analysis of Incorrect Options:** * **Halothane:** It is contraindicated in liver disease. It undergoes significant hepatic metabolism (up to 20%) and is notorious for causing **"Halothane Hepatitis"** (Type II) via immune-mediated mechanisms triggered by trifluoroacetylated proteins. It also significantly reduces hepatic blood flow. * **Ether:** It causes significant sympathetic stimulation and reduces hepatic blood flow through vasoconstriction. It is also associated with metabolic disturbances (hyperglycemia) not ideal for liver patients. **NEET-PG High-Yield Pearls:** * **Desflurane** is also safe (0.02% metabolism), but Isoflurane remains the classic textbook answer for its superior preservation of hepatic arterial flow. * **Sevoflurane** is safe but can be metabolized to inorganic fluoride; however, it is not typically associated with hepatotoxicity. * **Atracurium/Cisatracurium** are the preferred muscle relaxants in liver failure as they undergo **Hofmann elimination** (independent of liver/kidney function). * Avoid **Morphine** if possible, as its half-life is significantly prolonged in liver disease.

Question 57: A patient is undergoing preoperative airway assessment. Upon opening the mouth, visibility is limited up to the soft palate. According to the modified Mallampati classification, what is the grade of this airway?

A. Grade I
B. Grade II
C. Grade III (Correct Answer)
D. Grade IV

Explanation: ### Explanation The **Modified Mallampati Classification** is a clinical tool used to predict the ease of endotracheal intubation by assessing the relationship between the size of the tongue and the oral cavity. **Correct Answer: Grade III** In **Grade III**, the clinician can visualize the **soft palate and the base of the uvula**. Since the question states visibility is limited up to the soft palate (implying the faucial pillars and the rest of the uvula are obscured by the tongue), it fits the criteria for Grade III. This grade suggests a potentially difficult airway. **Analysis of Incorrect Options:** * **Grade I (Option A):** Full visibility of the soft palate, fauces, entire uvula, and anterior/posterior tonsillar pillars. * **Grade B (Option II):** Visibility of the soft palate, fauces, and the upper portion (tip) of the uvula. * **Grade D (Option IV):** Only the hard palate is visible. The soft palate is not visible at all. This indicates a very high probability of a difficult intubation. **Clinical Pearls for NEET-PG:** * **Method:** The test is performed with the patient sitting upright, head in a neutral position, mouth opened maximally, and **tongue protruded without phonation** (saying "Ah" can falsely improve the grade). * **Samsoon and Young's Modification:** The original Mallampati had 3 classes; Samsoon and Young added Class IV. * **Predictive Value:** While a high Mallampati score (III or IV) is a good predictor of a difficult glottic view (Cormack-Lehane Grade 3 or 4), it should be used in conjunction with other tests like the **Thyromental Distance (<6 cm)** and **inter-incisor gap (<3 cm)** for better accuracy.

Question 58: A 65-year-old man with a history of myocardial infarction is scheduled for elective cholecystectomy. His weight is 73 kg and height is 6'2". His packed cell volume is 35%. What is the maximal allowable blood loss for the procedure?

A. 600ml
B. 680ml
C. 700ml
D. 780ml (Correct Answer)

Explanation: ### Explanation The **Maximal Allowable Blood Loss (MABL)** is the amount of blood a patient can lose before their hemoglobin/hematocrit falls below a safe threshold, necessitating a blood transfusion. To calculate MABL, use the following formula: **MABL = [EBV × (Hct₀ - Hct_f)] / Hct_avg** 1. **Estimate Blood Volume (EBV):** For an adult male, EBV is approximately **70 ml/kg**. * EBV = 73 kg × 70 ml/kg = **5,110 ml**. 2. **Identify Hematocrit Values:** * Initial Hematocrit (**Hct₀**) = 35% (given). * Minimum acceptable Hematocrit (**Hct_f**): In a 65-year-old with a history of Myocardial Infarction (MI), the target hematocrit is generally **30%** to ensure adequate oxygen delivery to the myocardium. 3. **Calculate Average Hematocrit (Hct_avg):** (35 + 30) / 2 = **32.5%**. 4. **Final Calculation:** * MABL = [5,110 × (35 - 30)] / 32.5 * MABL = [5,110 × 5] / 32.5 = 25,550 / 32.5 ≈ **786 ml**. * The closest option is **780 ml (Option D)**. --- ### Analysis of Incorrect Options * **Options A, B, and C:** These values result from using incorrect EBV constants (e.g., 60 or 65 ml/kg) or assuming a lower "trigger" hematocrit (e.g., 21% or 24%). In a patient with ischemic heart disease, a higher trigger (30%) is mandatory, leading to a lower allowable loss than in a healthy young adult. --- ### High-Yield Clinical Pearls for NEET-PG * **EBV Constants:** Premature (95 ml/kg), Full-term neonate (85 ml/kg), Infant (80 ml/kg), Adult Male (70 ml/kg), Adult Female (65 ml/kg). * **Transfusion Trigger:** While 7 g/dL (Hct 21%) is the standard trigger for healthy patients, **10 g/dL (Hct 30%)** is the threshold for those with significant cardiopulmonary disease or elderly patients. * **Fluid Replacement:** Replace blood loss with crystalloids at a **3:1 ratio** or colloids/blood at a **1:1 ratio**.

Question 59: A nurse is assessing the motor function of an unconscious male client. Which of the following would the nurse plan to use to test the client's peripheral response to pain?

A. Sternal rub
B. Nail bed pressure (Correct Answer)
C. Pressure on the orbital rim
D. Squeezing of the sternocleidomastoid muscle

Explanation: **Explanation:** In the assessment of an unconscious patient, distinguishing between **central** and **peripheral** painful stimuli is crucial for evaluating neurological integrity and the Glasgow Coma Scale (GCS) motor component. **1. Why Nail Bed Pressure is Correct:** To test a **peripheral response**, the stimulus must be applied to a limb. Applying pressure to the nail bed (using a pen or similar object) triggers a spinal reflex or a purposeful withdrawal/localization response. This helps determine if the patient can perceive pain in the extremities and whether the motor pathway from the brain to the peripheral nerves is intact. **2. Analysis of Incorrect Options:** * **A. Sternal Rub:** This is a **central stimulus**. It involves firm pressure on the sternum and is used to assess the brain's overall arousal level rather than peripheral nerve function. * **C. Pressure on the Orbital Rim:** This involves applying pressure to the supraorbital notch. It is a **central stimulus** used to elicit a response from the cranial nerves and the brainstem. * **D. Squeezing the Sternocleidomastoid (Trapezius Squeeze):** Squeezing the trapezius muscle or the sternocleidomastoid is considered a **central stimulus** because it targets the proximal midline structures. **NEET-PG High-Yield Pearls:** * **Central Stimulus:** Used to elicit the "Best Motor Response" in GCS (e.g., Trapezius squeeze, Supraorbital pressure, Sternal rub). * **Peripheral Stimulus:** Used specifically to check for localized nerve injury or spinal cord integrity (e.g., Nail bed pressure). * **Clinical Caution:** Avoid repeated sternal rubs as they can cause bruising and tissue damage. Supraorbital pressure is contraindicated in patients with suspected frontal skull fractures. * **GCS Motor Scoring:** Localization (M5) requires the patient to move a limb toward a central stimulus, whereas Withdrawal (M4) is a flexion response to a peripheral stimulus.

Question 60: Which one of the following drugs has been shown to offer protection from gastric aspiration syndrome in a patient with symptoms of efflux?

A. Ondansetron
B. Metoclopramide (Correct Answer)
C. Sodium citrate
D. Atropine

Explanation: **Explanation:** The primary goal in preventing **Mendelson’s Syndrome (Gastric Aspiration Syndrome)** is to reduce gastric volume and increase gastric pH. **Metoclopramide (Option B)** is the correct answer because it is a **prokinetic agent**. It acts as a dopamine ($D_2$) antagonist and stimulates the release of acetylcholine in the gastrointestinal tract. This increases the Lower Esophageal Sphincter (LES) tone and enhances gastric emptying (gastric motility). By physically clearing the stomach of liquid contents, it directly reduces the volume available for aspiration, offering protection in patients with reflux symptoms. **Analysis of Incorrect Options:** * **Ondansetron (Option A):** A $5-HT_3$ receptor antagonist used primarily as an anti-emetic. While it prevents postoperative nausea and vomiting (PONV), it has no effect on gastric pH, volume, or motility. * **Sodium Citrate (Option C):** This is a non-particulate antacid. While it effectively **increases gastric pH** (making the aspirate less acidic), it actually **increases total gastric volume**. Therefore, it does not "clear" the stomach like a prokinetic. * **Atropine (Option D):** An anticholinergic that actually **decreases** LES tone and delays gastric emptying, potentially increasing the risk of aspiration. **NEET-PG High-Yield Pearls:** * **Mendelson’s Syndrome Criteria:** Gastric volume $> 25\text{ ml}$ ($0.4\text{ ml/kg}$) and pH $< 2.5$. * **Prophylaxis Triad:** H2 blockers (e.g., Ranitidine) to decrease acid production, Metoclopramide to decrease volume, and Sodium Citrate to neutralize existing acid. * **Sodium Citrate** is preferred over particulate antacids (like Magnesium hydroxide) because if aspirated, particulate antacids cause severe foreign-body pneumonitis.

Practice by Chapter

Preoperative Assessment Framework

Practice Questions

ASA Physical Status Classification

Practice Questions

Preoperative Laboratory Testing

Practice Questions

Cardiovascular Evaluation

Practice Questions

Pulmonary Evaluation

Practice Questions

Assessment of the Difficult Airway

Practice Questions

Medication Management

Practice Questions

NPO Guidelines

Practice Questions

Perioperative Anticoagulation Management

Practice Questions

Premedication

Practice Questions

Informed Consent

Practice Questions

Risk Stratification

Practice Questions

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