Preoperative Evaluation and Management — MCQs
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Which of the following solutions is a colloid?
A 78-year-old hypertensive, mildly asthmatic man receiving chemotherapy for colon cancer presents with symptomatic gallstones. Preoperative laboratory results revealed a hematocrit of 24% and urinalysis with 18 to 25 WBCs and gram-negative bacteria. Intravenous penicillin was administered preoperatively. The abdomen was shaved in the operating room. An open cholecystectomy was performed, and the common bile duct was explored despite a lack of indications. The wound was closed primarily with a Penrose drain exiting a separate stab wound. On postoperative day 3, the patient developed a wound infection. Which of the following changes in the care of this patient could have decreased the chance of a postoperative wound infection?
RBC infusion is not done with which of the following solutions?
A 65-year-old male with a history of acute onset vomiting and weight loss was diagnosed with stomach carcinoma and a Whipple's procedure was planned. Preanesthetic evaluation revealed deranged kidney function. Which inhalational agent is the agent of choice?
All of the following statements are true with relation to anesthesia and obesity except?
A 50-year-old diabetic and hypertensive patient on amlodipine and glimepiride is scheduled for elective AV fistula creation for dialysis due to acute kidney failure. What are the appropriate preoperative orders from an anesthesiologist's perspective?
What is the dose of atropine for premedication per kilogram of body weight?
A 40-year-old male is scheduled for an elective cholecystectomy. As a night duty doctor in the surgical ward, you are asked to advise the patient on when to stop oral intake. How many hours prior to surgery should the patient have their last light meal?
A 55-year-old male patient with hypertension, on ACE inhibitors, and who underwent CABG four years ago, is scheduled for hernia surgery. He has good effort tolerance. Which of the following investigations should be ordered preoperatively?
Preanesthetic medication is used for all except:
Preoperative Evaluation and Management Indian Medical PG Practice Questions and MCQs
Question 21: Which of the following solutions is a colloid?
- A. Normal saline
- B. Albumin (Correct Answer)
- C. Ringer lactate
- D. Dextrose 5%
Explanation: **Explanation:** Intravenous fluids are broadly classified into two categories: **Crystalloids** and **Colloids**, based on their molecular weight and ability to cross the semi-permeable capillary membrane. **Why Albumin is the Correct Answer:** **Albumin** is a natural **colloid**. Colloids contain large, high-molecular-weight molecules (usually >30,000 Daltons) that do not easily cross the healthy capillary endothelium. Because they remain within the intravascular compartment, they exert **oncotic pressure**, effectively drawing fluid into or maintaining fluid within the blood vessels. This makes them highly effective for rapid volume expansion. **Analysis of Incorrect Options:** * **Normal Saline (0.9% NaCl):** An isotonic **crystalloid**. It contains small electrolytes that freely pass through capillary pores into the interstitial space. * **Ringer’s Lactate (RL):** A balanced salt **crystalloid**. Like saline, it distributes throughout the entire extracellular fluid (ECF) compartment. * **Dextrose 5% (D5W):** A hypotonic **crystalloid**. Once the glucose is metabolized, it leaves behind free water which distributes across all body compartments (Intracellular + Extracellular). **High-Yield Clinical Pearls for NEET-PG:** * **Volume Expansion Ratio:** For every 100 mL of blood lost, you need ~300 mL of crystalloid (3:1 ratio) but only ~100 mL of colloid (1:1 ratio) to maintain hemodynamics. * **Synthetic Colloids:** Include Hydroxyethyl Starches (HES), Gelatins, and Dextrans. Note that HES is now restricted due to risks of acute kidney injury (AKI). * **Albumin Concentrations:** Available as 5% (iso-oncotic) and 25% (hyper-oncotic). * **Key Concept:** Crystalloids are the first-line choice for fluid resuscitation; colloids are reserved for specific indications like severe hypoalbuminemia or when crystalloids fail to achieve volume targets.
Question 22: A 78-year-old hypertensive, mildly asthmatic man receiving chemotherapy for colon cancer presents with symptomatic gallstones. Preoperative laboratory results revealed a hematocrit of 24% and urinalysis with 18 to 25 WBCs and gram-negative bacteria. Intravenous penicillin was administered preoperatively. The abdomen was shaved in the operating room. An open cholecystectomy was performed, and the common bile duct was explored despite a lack of indications. The wound was closed primarily with a Penrose drain exiting a separate stab wound. On postoperative day 3, the patient developed a wound infection. Which of the following changes in the care of this patient could have decreased the chance of a postoperative wound infection?
- A. Increasing the length of the preoperative hospital stay to prophylactically treat the asthma with steroids
- B. Treating the urinary infection prior to surgery (Correct Answer)
- C. Shaving the abdomen the night prior to surgery
- D. Continuing the prophylactic antibiotics for 3 postoperative days
Explanation: ### Explanation The correct answer is **B. Treating the urinary infection prior to surgery.** #### Why the Correct Answer is Right Postoperative wound infections (Surgical Site Infections - SSIs) are significantly increased by the presence of a **remote site infection** at the time of surgery. In this patient, the urinalysis (18-25 WBCs and gram-negative bacteria) indicates a symptomatic or asymptomatic urinary tract infection (UTI). Bacteria from the urinary tract can seed the surgical wound via the bloodstream (hematogenous spread), especially during the physiological stress of surgery. Eradicating any pre-existing infection before an elective procedure is a primary preventive measure to reduce SSI risk. #### Why the Incorrect Options are Wrong * **Option A:** Increasing preoperative hospital stay actually **increases** the risk of SSI. Prolonged hospitalization leads to colonization of the patient’s skin and respiratory tract with multidrug-resistant hospital flora (nosocomial pathogens). * **Option C:** Shaving the abdomen the night before surgery is a major risk factor. Shaving causes microscopic skin abrasions that serve as a nidus for bacterial multiplication. If hair removal is necessary, it should be done immediately before surgery using **electric clippers**, not razors. * **Option D:** Prophylactic antibiotics should ideally be discontinued within **24 hours** postoperatively. Extending them for 3 days does not further reduce SSI risk but does increase the risk of antibiotic resistance and *C. difficile* infection. #### NEET-PG High-Yield Pearls * **Timing of Prophylaxis:** Surgical antimicrobial prophylaxis should be administered within **60 minutes before the incision** (120 mins for Vancomycin/Fluoroquinolones). * **Remote Infections:** Elective surgery should be postponed until remote infections (UTI, skin infections, etc.) are fully treated. * **Hair Removal:** Clipping > Shaving. Shaving the night before increases SSI risk by up to 10-fold. * **Wound Classification:** Cholecystectomy with CBD exploration is classified as **Clean-Contaminated** (Class II). The use of a Penrose drain (open drain) also increases infection risk compared to closed-suction drains.
Question 23: RBC infusion is not done with which of the following solutions?
- A. Normal Saline (NS)
- B. 5% Dextrose
- C. Normosal
- D. Ringer's Lactate (RL) (Correct Answer)
Explanation: **Explanation:** The correct answer is **Ringer's Lactate (RL)**. The primary reason RL is contraindicated for co-administration with Packed Red Blood Cells (PRBCs) is its **calcium content**. Ringer’s Lactate contains ionized calcium (approximately 3 mEq/L). Blood products are typically anticoagulated with **Citrate**, which works by chelating calcium to prevent the clotting cascade. When RL is mixed with citrated blood, the calcium in the RL overcomes the anticoagulant effect of the citrate, leading to the formation of **microclots** within the infusion tubing or the blood bag. These clots can cause fatal pulmonary embolism if infused. **Analysis of Options:** * **Normal Saline (0.9% NaCl):** This is the **fluid of choice** for blood transfusion. It is isotonic and contains no calcium, making it safe to use for priming tubing or diluting PRBCs to decrease viscosity. * **5% Dextrose:** While it contains no calcium, it is **avoided** because it is hypotonic once the glucose is metabolized. This causes water to move into the RBCs (osmosis), leading to swelling and **hemolysis**. * **Normosol:** This is a balanced salt solution that is **calcium-free** (it uses magnesium instead). Therefore, it is compatible with blood products and does not cause clotting. **High-Yield Clinical Pearls for NEET-PG:** * **Plasmalyte A** is another calcium-free balanced salt solution that is safe for blood transfusion. * **Citrate Toxicity:** Rapid transfusion of multiple units can lead to hypocalcemia (as citrate binds the patient's endogenous calcium), manifesting as a prolonged QT interval on ECG. * **Ideal Ratio:** If dilution is needed to improve flow rates in emergencies, 0.9% NS is the only standard recommendation.
Question 24: A 65-year-old male with a history of acute onset vomiting and weight loss was diagnosed with stomach carcinoma and a Whipple's procedure was planned. Preanesthetic evaluation revealed deranged kidney function. Which inhalational agent is the agent of choice?
- A. Desflurane (Correct Answer)
- B. Sevoflurane
- C. Halothane
- D. Isoflurane
Explanation: ### Explanation The correct answer is **Desflurane (Option A)**. **Why Desflurane is the Agent of Choice:** In patients with **deranged kidney function** (Renal Failure), the primary goal is to use an anesthetic agent that undergoes minimal metabolism and does not produce nephrotoxic byproducts. * **Minimal Metabolism:** Desflurane is the most stable inhalational agent, with a metabolic rate of only **0.02%**. * **No Toxic Metabolites:** Unlike other agents, it does not produce inorganic fluoride ions in significant quantities, nor does it produce Compound A. Its elimination is almost entirely through the lungs, making it independent of renal clearance and safe for patients with renal impairment. **Why Other Options are Incorrect:** * **B. Sevoflurane:** It undergoes significant metabolism (5–8%) and reacts with carbon dioxide absorbents (like soda lime) to produce **Compound A**, which is nephrotoxic in laboratory animals. It also results in higher serum inorganic fluoride levels, making it less ideal than Desflurane in renal failure. * **C. Halothane:** It has a high metabolic rate (up to 20%) and is primarily associated with hepatotoxicity ("Halothane Hepatitis"). It also sensitizes the myocardium to catecholamines, which is risky in elderly patients. * **D. Isoflurane:** While Isoflurane is also considered safe in renal failure (metabolism rate 0.2%), **Desflurane is superior** due to its even lower metabolic rate and faster recovery profile. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolism of Inhalational Agents (Descending Order):** Halothane (20%) > Sevoflurane (5-8%) > Enflurane (2%) > Isoflurane (0.2%) > Desflurane (0.02%). * **Agent of Choice for Renal Failure:** Desflurane (due to least metabolism) or Isoflurane. * **Agent of Choice for Liver Failure:** Isoflurane (preserves hepatic blood flow). * **Agent of Choice for Day Care Surgery:** Desflurane (fastest recovery due to lowest blood-gas solubility coefficient: 0.42).
Question 25: All of the following statements are true with relation to anesthesia and obesity except?
- A. The induction dose of propofol is given according to lean body weight.
- B. Dose of succinyl choline is increased in obese patients.
- C. There is prolonged effect of vecuronium in obese patients if given according to total body weight.
- D. The maintenance dose of propofol is given according to total body weight. (Correct Answer)
Explanation: In obese patients, drug dosing is complex because physiological changes (increased fat mass, increased blood volume, and altered cardiac output) affect pharmacokinetics. **Explanation of the Correct Answer (Option D):** The statement is **false** because the **maintenance dose** of Propofol (via infusion) should be calculated based on **Lean Body Weight (LBW)**, not Total Body Weight (TBW). Using TBW for maintenance leads to excessive drug accumulation and delayed emergence, as Propofol clearance does not increase linearly with total weight. **Analysis of Other Options:** * **Option A (True):** The **induction dose** of Propofol is based on **LBW**. This is because the initial distribution is to the vessel-rich group (brain), and dosing by TBW would lead to profound hypotension and overdosage. * **Option B (True):** Succinylcholine is an exception. Its dose is based on **TBW**. Obese patients have increased pseudocholinesterase activity and a larger extracellular fluid volume, necessitating a higher dose (approx. 1.5 mg/kg TBW) to ensure excellent intubating conditions. * **Option C (True):** Vecuronium and Rocuronium are relatively hydrophilic. If dosed by TBW, the plasma concentration becomes excessively high, leading to a **prolonged duration of action**. Therefore, they should be dosed based on **Ideal Body Weight (IBW)** or LBW. **High-Yield Clinical Pearls for NEET-PG:** 1. **Dosing Summary:** * **TBW:** Succinylcholine, Dexmedetomidine. * **LBW:** Propofol (Induction & Maintenance), Fentanyl, Remifentanil. * **IBW:** Vecuronium, Rocuronium. 2. **Airway:** Obesity is a predictor of difficult mask ventilation (due to redundant tissue) rather than just difficult intubation. 3. **Pre-oxygenation:** Always perform in the **"Ramped Position"** (Head-Elevated Laryngoscopy Position - HELP) to improve functional residual capacity (FRC) and prolong apnea tolerance.
Question 26: A 50-year-old diabetic and hypertensive patient on amlodipine and glimepiride is scheduled for elective AV fistula creation for dialysis due to acute kidney failure. What are the appropriate preoperative orders from an anesthesiologist's perspective?
- A. Stop amlodipine but continue glimepiride.
- B. Continue amlodipine, stop glimepiride, and switch to insulin a day prior. (Correct Answer)
- C. Stop both amlodipine and glimepiride.
- D. Administer insulin and schedule surgery for one week later.
Explanation: ### Explanation The management of chronic medications in the perioperative period is a high-yield topic for NEET-PG, focusing on maintaining physiological stability while preventing metabolic crises. **1. Why Option B is Correct:** * **Amlodipine (Calcium Channel Blocker):** Antihypertensives (except ACE inhibitors and ARBs) are generally **continued** on the day of surgery to prevent rebound hypertension and intraoperative hemodynamic instability. * **Glimepiride (Sulfonylurea):** Oral hypoglycemic agents (OHAs) carry a high risk of **prolonged hypoglycemia** during the fasting (NPO) period. In patients with renal failure, the half-life of sulfonylureas is further prolonged. Therefore, OHAs are stopped, and the patient is switched to **short-acting insulin**, which allows for precise, "sliding-scale" glycemic control during the perioperative stress response. **2. Analysis of Incorrect Options:** * **Option A:** Stopping amlodipine risks a hypertensive crisis during induction. Continuing glimepiride while NPO is dangerous due to hypoglycemia risk. * **Option C:** Stopping amlodipine is unnecessary and potentially harmful. While glimepiride should be stopped, the patient requires an alternative (insulin) to prevent hyperglycemia/ketoacidosis. * **Option D:** Elective surgery for AV fistula in acute/chronic renal failure is time-sensitive for dialysis access. Delaying by a week is clinically inappropriate if the patient can be stabilized with insulin immediately. **3. Clinical Pearls for NEET-PG:** * **ACEIs/ARBs:** Usually stopped 24 hours prior to avoid "refractory hypotension" under general anesthesia. * **Metformin:** Ideally stopped 24–48 hours prior due to the risk of **lactic acidosis**, especially in patients with renal impairment or those receiving IV contrast. * **Statins & Beta-blockers:** Always **continued** (Beta-blockers reduce perioperative myocardial ischemia). * **SGLT-2 Inhibitors:** Stopped 3–4 days prior to avoid euglycemic ketoacidosis.
Question 27: What is the dose of atropine for premedication per kilogram of body weight?
- A. 10 mg
- B. 0.1 mg
- C. 0.01 mg (Correct Answer)
- D. 0.001 mg
Explanation: ### Explanation **Correct Answer: C. 0.01 mg** **Understanding the Concept:** Atropine is a competitive muscarinic antagonist used in premedication primarily for its **antisialagogue** (reduction of secretions) and **vagolytic** (prevention of bradycardia) effects. In clinical anesthesia, the standard dose for premedication is **0.01 mg/kg to 0.02 mg/kg**. For an average 60 kg adult, this translates to a total dose of approximately 0.6 mg, which is the standard ampoule size. **Analysis of Options:** * **A. 10 mg:** This is a massive overdose. Such a dose would lead to severe "Atropine Toxicity" (central anticholinergic syndrome), characterized by delirium, hyperthermia, and potentially fatal arrhythmias. * **B. 0.1 mg:** While this is a common dose for certain pediatric scenarios, as a per-kilogram dose, it is 10 times the standard requirement for an adult. * **D. 0.001 mg:** This dose is sub-therapeutic. At very low doses (less than 0.4 mg total in adults), atropine can paradoxically cause **bradycardia** due to its central effects or blockade of presynaptic inhibitory M1 receptors. **High-Yield NEET-PG Pearls:** * **Route:** Usually administered Intramuscularly (IM) 30–60 minutes before induction or Intravenously (IV) immediately before induction. * **Drug of Choice:** While atropine is common, **Glycopyrrolate (0.005–0.01 mg/kg)** is often preferred as a premedication because it does not cross the blood-brain barrier (quaternary ammonium) and has a more potent antisialagogue effect. * **Contraindications:** Avoid in patients with **Narrow-angle Glaucoma**, Pyloric stenosis, and Tachyarrhythmias. * **Scopolamine:** Another anticholinergic used for premedication, specifically for its superior sedative and anti-emetic properties.
Question 28: A 40-year-old male is scheduled for an elective cholecystectomy. As a night duty doctor in the surgical ward, you are asked to advise the patient on when to stop oral intake. How many hours prior to surgery should the patient have their last light meal?
- A. 4 hours
- B. 6 hours (Correct Answer)
- C. 8 hours
- D. 12 hours
Explanation: ### Explanation The core objective of preoperative fasting (NPO status) is to reduce the volume and acidity of gastric contents, thereby minimizing the risk of **pulmonary aspiration**—a life-threatening complication during the induction of general anesthesia. **Why 6 hours is the correct answer:** According to the **ASA (American Society of Anesthesiologists) guidelines**, a minimum fasting period of **6 hours** is required after a **light meal** (e.g., toast and clear liquid) or non-human milk. This duration allows for adequate gastric emptying of solid particles. **Analysis of Incorrect Options:** * **4 hours (Option A):** This is the fasting requirement specifically for **breast milk** in infants. It is insufficient for solid food or light meals in adults. * **8 hours (Option C):** This is the recommended fasting period for a **heavy meal** (specifically those containing fried foods, fatty foods, or meat), as fat significantly delays gastric emptying. * **12 hours (Option D):** While "NPO after midnight" was a traditional practice, modern guidelines discourage prolonged fasting to prevent dehydration, hypoglycemia, and patient discomfort. **High-Yield Clinical Pearls for NEET-PG:** * **Clear Liquids:** 2 hours (e.g., water, fruit juices without pulp, carbonated beverages, clear tea, black coffee). * **Breast Milk:** 4 hours. * **Infant Formula:** 6 hours. * **Light Meal/Non-human milk:** 6 hours. * **Heavy Meal (Fatty/Fried):** 8 hours. * **Chewing Gum:** Generally, elective surgery is not delayed for gum chewing if no solids were swallowed, but it is best avoided. * **High-Risk Patients:** Patients with GERD, morbid obesity, or diabetes mellitus (gastroparesis) are often treated as "full stomachs" regardless of fasting time.
Question 29: A 55-year-old male patient with hypertension, on ACE inhibitors, and who underwent CABG four years ago, is scheduled for hernia surgery. He has good effort tolerance. Which of the following investigations should be ordered preoperatively?
- A. Routine preoperative evaluation and clinical assessment
- B. Routine preoperative evaluation, clinical assessment, and stress testing (Correct Answer)
- C. Routine preoperative evaluation, clinical assessment, and angiography to assess patency
- D. Routine preoperative evaluation, clinical assessment, and evaluation of surgical scars
Explanation: **Explanation:** The management of a patient with a history of Coronary Artery Bypass Grafting (CABG) undergoing non-cardiac surgery depends on the **time elapsed since surgery** and the **current clinical status**. **Why Option B is Correct:** According to the ACC/AHA guidelines, if a patient has undergone CABG within the last 5 years and remains asymptomatic with good functional capacity, further testing is usually not required. However, in the context of NEET-PG and standard clinical protocols for high-risk cardiac history (like CABG), a **Stress Test** is the preferred non-invasive investigation to assess current myocardial reserve and silent ischemia before surgery, even if the patient claims good effort tolerance. It bridges the gap between simple clinical assessment and invasive angiography. **Analysis of Incorrect Options:** * **Option A:** Insufficient. While clinical assessment is vital, a history of CABG and hypertension necessitates objective cardiac evaluation beyond just a routine physical exam. * **Option C:** Angiography is an invasive procedure and is not indicated for routine preoperative clearance unless the patient has unstable symptoms or the stress test shows high-risk features. * **Option D:** Evaluation of surgical scars is a minor part of the physical exam and does not provide information regarding the patient’s current physiological or cardiac status. **High-Yield Clinical Pearls for NEET-PG:** 1. **ACE Inhibitors:** Usually withheld 24 hours before surgery to prevent "refractory hypotension" during induction of anesthesia. 2. **Functional Capacity:** Measured in METs (Metabolic Equivalents). >4 METs (climbing two flights of stairs) indicates good functional capacity. 3. **Post-CABG:** If CABG was performed <5 years ago and the patient is asymptomatic, they are generally considered "optimized" for surgery. 4. **Goldman’s Index:** Used for cardiac risk stratification in non-cardiac surgery (JVP/S3 gallop is the most significant predictor).
Question 30: Preanesthetic medication is used for all except:
- A. Decrease anesthetic dose
- B. Decrease blood pressure (Correct Answer)
- C. Prevent aspiration
- D. Produce amnesia for perioperative events
Explanation: **Explanation:** Preanesthetic medication refers to the administration of drugs prior to anesthesia to facilitate a smooth induction, maintain patient safety, and enhance recovery. **Why "Decrease blood pressure" is the correct answer:** The primary goal of premedication is **not** to decrease blood pressure. While some premedications (like opioids or alpha-2 agonists) may cause a slight drop in BP as a side effect, hypotension is generally undesirable before induction as it can compromise organ perfusion during the transition to general anesthesia. Hypertension, if present, should be managed with the patient’s regular antihypertensive regimen rather than acute "premedication." **Analysis of Incorrect Options:** * **A. Decrease anesthetic dose:** Drugs like opioids (Fentanyl) and benzodiazepines (Midazolam) provide synergistic effects, significantly reducing the Minimum Alveolar Concentration (MAC) of inhalational agents and the required dose of intravenous induction agents. * **C. Prevent aspiration:** Prokinetic agents (Metoclopramide) and H2-blockers (Ranitidine) or Proton Pump Inhibitors (Pantoprazole) are used to decrease gastric volume and increase pH, reducing the risk of Mendelson’s syndrome (aspiration pneumonitis). * **D. Produce amnesia:** Benzodiazepines (especially Midazolam) are the gold standard for providing anterograde amnesia, ensuring the patient has no distressing memories of the perioperative period. **High-Yield Clinical Pearls for NEET-PG:** * **Glycopyrrolate:** Preferred over Atropine as an antisialagogue because it does not cross the blood-brain barrier (no central anticholinergic syndrome). * **Mendelson’s Syndrome:** Defined as aspiration of gastric contents >25ml with a pH <2.5. * **Ideal Timing:** Oral premedication is typically given 60–90 minutes before surgery; IM/IV routes are faster. * **Vagal Inhibition:** Anticholinergics are used to prevent reflex bradycardia during intubation or oculocardiac reflex.
Practice by Chapter
Preoperative Assessment Framework
Practice Questions
ASA Physical Status Classification
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Preoperative Laboratory Testing
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Cardiovascular Evaluation
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Pulmonary Evaluation
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Assessment of the Difficult Airway
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Medication Management
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NPO Guidelines
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Perioperative Anticoagulation Management
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Premedication
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Informed Consent
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Risk Stratification
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