Preoperative Evaluation and Management Practice Questions

Q: Anesthetic management of a 30-year-old lady with myasthenia gravis includes all of the following except?

Generous doses of opioids. **Explanation:** The anesthetic management of **Myasthenia Gravis (MG)** focuses on minimizing respiratory depression and managing the altered response to neuromuscular blocking agents. **Why "Generous doses of opioids" is the correct (except) option:** Patients with MG have significant bulbar and respiratory muscle weakness. **Opioids** cause dose-dependent respiratory depression and can suppress the cough reflex, leading to a high risk of postoperative respiratory failure and aspiration. Therefore, opioids should be used very cautiously (titrated to effect) or avoided in favor of multimodal analgesia; "generous doses" are contraindicated. **Analysis of other options:** * **Regional Anesthesia (A):** This is often the preferred technique (where applicable) as it avoids the need for systemic neuromuscular blockers and airway manipulation, reducing the risk of a myasthenic crisis. * **Corticosteroids (B):** Many MG patients are on chronic steroid therapy to manage their autoimmune condition. These should be continued perioperatively, and "stress doses" may be required to prevent adrenal insufficiency. * **Dose of Anticholinesterase (C):** Pyridostigmine is often reduced or withheld on the morning of surgery to avoid interactions with muscle relaxants and to minimize vagotonic effects (like excessive secretions/bradycardia), though this is tailored to the patient's severity. **High-Yield NEET-PG Pearls:** 1. **Muscle Relaxant Response:** MG patients are **exquisitely sensitive** to Non-depolarizing Muscle Relaxants (NDMRs) like Vecuronium (use 1/10th dose) and **resistant** to Depolarizing agents (Succinylcholine). 2. **Osserman Classification:** Used to grade the severity of MG. 3. **Predictors of Post-op Ventilation:** Disease duration >6 years, chronic respiratory disease, pyridostigmine dose >750mg/day, and Vital Capacity <2.9L. 4. **Reversal:** Sugammadex is preferred over Neostigmine to avoid cholinergic crisis.

Q: Which is the most potent antiemetic agent used in the preoperative period?

Hyoscine. ### Explanation The correct answer is **Hyoscine (Scopolamine)**. **Why Hyoscine is the Correct Choice:** Hyoscine is a tertiary amine anticholinergic that effectively crosses the blood-brain barrier. It acts primarily on the **muscarinic receptors in the vestibular apparatus** and the nucleus tractus solitarius. Among the options provided, it is the most potent agent for preventing **Postoperative Nausea and Vomiting (PONV)**, particularly when motion sickness or vestibular stimulation is a factor. In clinical practice, it is often administered as a transdermal patch (1.5 mg) preoperatively to provide sustained antiemetic effects for up to 72 hours. **Analysis of Incorrect Options:** * **Glycopyrrolate:** A quaternary ammonium compound that does **not** cross the blood-brain barrier. While it is excellent for reducing secretions (antisialagogue), it has no central antiemetic effect. * **Atropine:** A tertiary amine that crosses the blood-brain barrier but has minimal effect on the vomiting center compared to Hyoscine. It is primarily used to treat bradycardia or as an antisialagogue. * **Metoclopramide:** A dopamine (D2) antagonist. While it has prokinetic and antiemetic properties, its potency in preventing PONV is significantly lower than Hyoscine or 5-HT3 antagonists (like Ondansetron). **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for Motion Sickness:** Hyoscine (Scopolamine). * **Antisialagogue Potency:** Scopolamine > Glycopyrrolate > Atropine. * **Sedative Potency:** Scopolamine > Atropine > Glycopyrrolate (Zero). * **Tachycardia Potency:** Atropine > Glycopyrrolate > Scopolamine. * **Central Anticholinergic Syndrome:** Caused by Atropine/Hyoscine; treated with **Physostigmine** (a tertiary amine acetylcholinesterase inhibitor).

Q: What is the concentration of Potassium in Ringer Lactate solution?

4 mEq/L. **Explanation:** Ringer’s Lactate (RL), also known as Hartmann’s solution, is a balanced salt solution designed to mimic the electrolyte composition of human plasma. It is the fluid of choice for perioperative maintenance and resuscitation in most surgical cases. **Why 4 mEq/L is correct:** The concentration of **Potassium (K⁺) in Ringer’s Lactate is exactly 4 mEq/L**. This concentration is intentionally set to match the normal physiological range of potassium in human extracellular fluid (3.5–5.0 mEq/L). Because it contains potassium, RL should be used with caution in patients with renal failure or pre-existing hyperkalemia. **Analysis of Incorrect Options:** * **A (1 mEq/L) & C (2 mEq/L):** These concentrations are too low to maintain physiological homeostasis and do not reflect the standard formulation of RL. * **D (6 mEq/L):** This concentration exceeds the normal physiological limit. Infusing a fluid with 6 mEq/L of potassium as a primary maintenance fluid could potentially induce iatrogenic hyperkalemia. **High-Yield Clinical Pearls for NEET-PG:** * **Composition of RL (per Liter):** Na⁺ (130–131 mEq), Cl⁻ (109–111 mEq), K⁺ (4 mEq), Ca²⁺ (3 mEq), and Lactate (28 mEq). * **Osmolarity:** RL is slightly hypotonic compared to plasma (approx. 273 mOsm/L). * **Metabolism:** The lactate in RL is converted by the **liver** into bicarbonate, making it useful in treating metabolic acidosis. * **Contraindication:** RL should not be used as a diluent for blood transfusions because the **Calcium** in it can react with the anticoagulant (CPDA) in blood bags, leading to clot formation.

Q: Which of the following statements regarding preoperative modification of drugs is incorrect?

Low-dose aspirin should be stopped 7 days before surgery.. **Explanation:** The correct answer is **B** because the current clinical guidelines recommend that **low-dose aspirin (75–150 mg)** should generally be **continued** throughout the perioperative period, especially in patients with coronary artery disease or drug-eluting stents. The risk of major adverse cardiac events (MACE) from stopping aspirin often outweighs the risk of surgical bleeding. It is only stopped (usually for 7–10 days) in specific "closed-space" surgeries where even minor bleeding is catastrophic, such as intracranial, posterior chamber of the eye, or deep spinal procedures. **Analysis of other options:** * **A. Lithium:** It is traditionally stopped **48–72 hours** before major surgery because it prolongs the action of neuromuscular blocking agents and carries a risk of toxicity due to perioperative dehydration and electrolyte shifts. * **C. Tricyclic Antidepressants (TCAs):** These can be **continued** until the day of surgery. However, the anesthesiologist must be cautious as TCAs increase sympathetic tone, potentially leading to exaggerated responses to indirect-acting sympathomimetics (like ephedrine) and an increased risk of arrhythmias. * **D. Oral Anticoagulants (e.g., Warfarin):** These are typically stopped **4–5 days** prior to surgery to allow the INR to normalize (<1.5). High-risk patients may require "bridging therapy" with Heparin. **High-Yield Clinical Pearls for NEET-PG:** * **Continue:** Beta-blockers, Calcium channel blockers, Statins, and most Antiepileptics. * **Stop on the day of surgery:** ACE inhibitors and ARBs (due to risk of refractory hypotension), and Oral Hypoglycemic Agents (Metformin is stopped 24–48 hours prior to avoid lactic acidosis). * **MAO Inhibitors:** Traditionally stopped 2 weeks prior, but modern practice often allows continuation with strict avoidance of Pethidine (risk of Serotonin Syndrome).

Q: Which of the following statements about Ringer lactate is true?

Lactate concentration is 29 mEq/L. **Explanation:** Ringer’s Lactate (RL), also known as Hartmann’s solution, is a balanced salt solution frequently used in perioperative fluid management. It is designed to be more physiological than Normal Saline (0.9% NaCl) by mimicking the electrolyte composition of human plasma. **1. Why Option D is Correct:** The lactate concentration in Ringer’s Lactate is exactly **28–29 mEq/L**. In the body, this lactate is metabolized by the liver into bicarbonate, which acts as a buffer against metabolic acidosis. This makes RL the fluid of choice for large-volume resuscitation and replacement of extracellular fluid losses. **2. Why the Other Options are Incorrect:** * **Option A (Chloride):** The chloride concentration in RL is **109 mEq/L**, not 111 mEq/L. This lower chloride content (compared to 154 mEq/L in Normal Saline) helps prevent hyperchloremic metabolic acidosis. * **Option B (Sodium):** The sodium concentration is **130–131 mEq/L**. A concentration of 45 mEq/L is seen in hypotonic solutions like 1/3rd Normal Saline. * **Option C (Potassium):** The potassium concentration is **4 mEq/L**, which is similar to normal plasma levels. 5 mEq/L is the upper limit of normal plasma potassium but is not the standard concentration in RL. **High-Yield Clinical Pearls for NEET-PG:** * **Osmolarity:** RL is slightly **hypotonic** (approx. 273 mOsm/L) compared to plasma (285–295 mOsm/L). * **Calcium Content:** RL contains **3 mEq/L of Calcium**. Therefore, it should **not** be administered in the same line as citrated blood products, as the calcium can bind to the citrate anticoagulant and cause clot formation. * **Contraindications:** Avoid RL in patients with severe liver disease (unable to metabolize lactate) or in cases of head injury (due to its slight hypotonicity, which may worsen cerebral edema).

Q: Which of the following is NOT part of routine preoperative preparation?

Erythropoietin. **Explanation:** The goal of routine preoperative preparation is to alleviate patient anxiety, provide sedation, and minimize autonomic reflexes or secretions. **Why Erythropoietin is the correct answer:** Erythropoietin is a glycoprotein hormone that stimulates red blood cell production. It is **not** a routine preoperative medication. Its use is strictly limited to specific clinical scenarios, such as patients with chronic kidney disease or those undergoing major elective surgery with anticipated high blood loss who refuse blood transfusions (e.g., Jehovah’s Witnesses). It requires weeks to be effective and carries risks of hypertension and thromboembolism, making it unsuitable for routine immediate preoperative use. **Why the other options are incorrect:** * **Diazepam & Midazolam (Benzodiazepines):** These are the most common agents used for **pre-anesthetic medication**. They provide anxiolysis and anterograde amnesia. Midazolam is preferred due to its shorter half-life and water solubility (less pain on injection). * **Atropine (Anticholinergic):** While no longer used "universally" for every patient, it remains a standard component of preoperative preparation to reduce salivary and bronchial secretions (antisialagogue effect) and to prevent reflex bradycardia during induction or surgery. **High-Yield NEET-PG Pearls:** * **Ideal time for Pre-medication:** Usually 60–90 minutes before induction. * **Midazolam:** Most common pre-medicant; provides excellent amnesia. * **Glycopyrrolate:** Often preferred over Atropine as an antisialagogue because it does not cross the blood-brain barrier (no central anticholinergic syndrome). * **Aspiration Prophylaxis:** Routine in "at-risk" patients using H2 blockers (Ranitidine) or Proton Pump Inhibitors (Pantoprazole) and prokinetics (Metoclopramide).

Question 1

Anesthetic management of a 30-year-old lady with myasthenia gravis includes all of the following except?

Accepted Answer

Generous doses of opioids

Answer

Regional anesthesia

Answer

Corticosteroids

Answer

Dose of anticholinesterase to be decreased

Question 2

Which of the following is NOT a true anaesthetic implication of obesity?

Accepted Answer

There is a decrease in cardiac output.

Answer

There is a high risk of regurgitation.

Answer

There is an increased risk of perioperative hypoxemia.

Answer

There is a high risk of renal disease.

Question 3

A 58-year-old male factory worker scheduled to undergo a left inguinal hernia repair is noted to have a severe chronic cough. Pulmonary function tests revealed reduction of forced expiratory volume in 1 second (FEV1) and reduction of FEV1/forced vital capacity (FVC) ratio associated with emphysema. Before rescheduling surgery, which of the following would improve residual pulmonary function?

Accepted Answer

Trial of ipratropium bromide bronchodilator therapy

Answer

Cromolyn

Answer

Cough suppressants

Answer

Bilateral carotid body resection

Question 4

Which is the most potent antiemetic agent used in the preoperative period?

Accepted Answer

Hyoscine

Answer

Glycopyrrolate

Answer

Atropine

Answer

Metoclopramide

Question 5

Which drug is used to control secretions during general anesthesia?

Accepted Answer

Glycopyrrolate

Answer

Hyoscine

Answer

Pethidine

Answer

Lorazepam

Question 6

What is the concentration of Potassium in Ringer Lactate solution?

Accepted Answer

4 mEq/L

Answer

1 mEq/L

Answer

2 mEq/L

Answer

6 mEq/L

Question 7

Which of the following statements regarding preoperative modification of drugs is incorrect?

Accepted Answer

Low-dose aspirin should be stopped 7 days before surgery.

Answer

Lithium should be stopped 2-3 days before surgery.

Answer

Tricyclic antidepressants can be continued until the day of operation.

Answer

Oral anticoagulants should be stopped 4 days before surgery.

Question 8

Which of the following patients should have their surgery deferred for further cardiac evaluation?

Accepted Answer

A 55-year-old female patient with Mobitz type 2 heart block rhythm.

Answer

A 60-year-old chronic smoker and diabetic with uncontrolled blood sugar and hypertension (BP=159/100).

Answer

A 70-year-old male patient with congestive heart failure who has a history of dyspnea on exertion.

Answer

A 45-year-old female patient who has shortness of breath while climbing upstairs.

Question 9

Which of the following statements about Ringer lactate is true?

Accepted Answer

Lactate concentration is 29 mEq/L

Answer

Chloride (Cl-) concentration is 111 mEq/L

Answer

Sodium (Na+) concentration is 45 mEq/L

Answer

Potassium (K+) concentration is 5 mEq/L

Question 10

Which of the following is NOT part of routine preoperative preparation?

Accepted Answer

Erythropoietin

Answer

Diazepam

Answer

Midazolam

Answer

Atropine

Preoperative Evaluation and Management — MCQs

Preoperative Evaluation and Management — MCQs

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