Anesthetic Equipment and Monitoring Practice Questions

Q: Which artery is most commonly cannulated for invasive blood pressure monitoring?

Radial artery. **Explanation:** **Radial Artery (Correct Answer):** The radial artery is the most common site for invasive blood pressure (IBP) monitoring because it is superficial, easily accessible, and technically simple to cannulate. The primary safety feature of the radial artery is the **dual blood supply** to the hand via the palmar arches. Before cannulation, the **Modified Allen’s Test** is traditionally performed to ensure adequate collateral circulation from the ulnar artery, minimizing the risk of digital ischemia. **Incorrect Options:** * **Femoral Artery:** While commonly used in emergency or low-flow states (shock) due to its large caliber, it carries a higher risk of infection (due to proximity to the groin) and pseudoaneurysm formation. It is generally a second-line choice. * **Carotid Artery:** This is **never** used for routine IBP monitoring. Cannulation or even prolonged compression poses a severe risk of stroke, carotid sinus syncope, or hematoma-induced airway obstruction. * **Ulnar Artery:** Although it provides collateral flow, it is deeper and more difficult to palpate than the radial artery. It is usually avoided unless the radial artery is unavailable, as it is often the dominant supplier to the hand. **High-Yield Clinical Pearls for NEET-PG:** * **Order of preference:** Radial > Dorsalis Pedis > Femoral > Brachial. * **Transducer Level:** For accurate readings, the transducer must be leveled at the **Phlebostatic Axis** (4th intercostal space, mid-axillary line), representing the level of the right atrium. * **Damping:** An "overdamped" wave (slurred) underestimates systolic BP; an "underdamped" wave (ringing) overestimates systolic BP. * **Complication:** The most common complication of arterial cannulation is **thrombosis**, though it is rarely symptomatic due to collateral flow.

Q: Clayton is used in a closed breathing system for what purpose?

As an indicator. In a closed breathing system, carbon dioxide (CO₂) must be removed from the exhaled gases before they are rebreathed. This is achieved using **Soda Lime** or **Barium Lime** canisters. **Why "As an indicator" is correct:** Soda lime contains a pH-sensitive dye known as an **indicator**. As CO₂ is absorbed, it reacts with water to form carbonic acid, which then reacts with the hydroxides in the lime. This process consumes the alkaline reserve, causing the pH to drop. **Clayton Yellow** (also known as Titan Yellow) is one such indicator that changes color (typically from red to yellow) when the absorbent becomes exhausted and the pH falls below a critical level (approx. 12.0). This visual cue alerts the anesthesiologist that the canister needs replacement. **Explanation of Incorrect Options:** * **A. As a hardener:** Silica or Kieselguhr is added to soda lime to increase its hardness and prevent the formation of alkaline dust, which can cause bronchospasm. * **B. As an absorbent:** The primary absorbents are Calcium Hydroxide [Ca(OH)₂], Sodium Hydroxide (NaOH), and Potassium Hydroxide (KOH). * **C. As a softener:** Softeners are not a standard component of CO₂ absorption granules. **High-Yield Clinical Pearls for NEET-PG:** * **Common Indicators:** Ethyl Violet (most common, changes from white to purple), Phenolphthalein (white to pink), and Clayton Yellow (red to yellow). * **Composition of Soda Lime:** 80% Calcium hydroxide, 4% Sodium hydroxide, 1% Potassium hydroxide, and 15% water. * **Mesh Size:** The standard size for granules is **4–8 mesh** to provide a balance between high surface area for absorption and low resistance to gas flow. * **Compound A:** Formed by the degradation of Sevoflurane in dry soda lime.

Q: What does MAC stand for in anesthesiology?

Minimum alveolar concentration. **Explanation:** **1. Why the Correct Answer is Right:** **Minimum Alveolar Concentration (MAC)** is a fundamental concept in inhalational anesthesia. It is defined as the concentration of an anesthetic vapor in the alveoli (at 1 atmosphere) that prevents a **motor response (movement)** to a standard surgical stimulus (like a skin incision) in **50% of patients**. It is essentially the ED50 of inhalational anesthetics, used to compare the potency of different agents. Potency is inversely proportional to MAC (e.g., Halothane has a low MAC and high potency, while Nitrous Oxide has a high MAC and low potency). **2. Why the Incorrect Options are Wrong:** * **B & C (Minimal Analgesic/Anesthetic Concentration):** These are non-standard terms. While MAC relates to anesthesia, the specific physiological measurement is based on the **alveolar** concentration, which reflects the partial pressure of the gas in the brain at equilibrium. * **D (Maximum Alveolar Concentration):** This is incorrect because MAC represents the *minimum* amount required to achieve the desired effect in half the population, not the maximum. **3. High-Yield Clinical Pearls for NEET-PG:** * **MAC-Awake:** The concentration at which 50% of patients will open their eyes to command (usually **0.3–0.5 MAC**). * **MAC-BAR:** The concentration required to **B**lock **A**utonomic **R**esponses to surgical stimulation (usually **1.7–2.0 MAC**). * **Factors Increasing MAC (Requirement increases):** Hyperthermia, hypernatremia, chronic alcohol abuse, and increased central neurotransmitters (e.g., cocaine, MAO inhibitors). * **Factors Decreasing MAC (Requirement decreases):** Hypothermia, hyponatremia, pregnancy, acute alcohol intoxication, old age, and opioids/sedatives. * **Note:** MAC is **not** affected by the duration of anesthesia or the patient's gender.

Q: For central venous pressure monitoring, all are true except?

Pulmonary capillary wedge pressure normally is 10-20 mmHg.. **Explanation:** The correct answer is **C** because the normal range for **Pulmonary Capillary Wedge Pressure (PCWP)** is actually **6–12 mmHg**. A value of 10–20 mmHg would be considered elevated, often indicating left ventricular failure or fluid overload. **Analysis of Options:** * **Option A (True):** The **Right Internal Jugular Vein (IJV)** is the preferred site for CVP monitoring because it offers a straight path to the superior vena cava, has a lower risk of pneumothorax compared to the subclavian vein, and is easily accessible for ultrasound guidance. * **Option B (True):** CVP monitoring is a standard clinical tool used to assess **fluid status** (preload) and right ventricular function, helping guide fluid resuscitation in critically ill patients. * **Option D (True):** When a Swan-Ganz (Pulmonary Artery) catheter enters the pulmonary artery, the pressure waveform changes. The appearance of a **dicrotic notch** (caused by the closure of the pulmonary valve) is the definitive sign that the catheter has moved from the right ventricle into the pulmonary artery. **High-Yield Clinical Pearls for NEET-PG:** * **Zeroing Level:** CVP should be zeroed at the **phlebostatic axis** (4th intercostal space, mid-axillary line). * **CVP Waveforms:** * **'a' wave:** Atrial contraction (absent in Atrial Fibrillation; giant 'a' waves in Tricuspid Stenosis). * **'c' wave:** Ventricular contraction (tricuspid valve bulging into the atrium). * **'v' wave:** Venous filling against a closed tricuspid valve (large 'v' waves in Tricuspid Regurgitation). * **West Zones:** For accurate PCWP readings, the catheter tip must be in **West Zone 3** of the lung, where continuous blood flow exists.

Q: Which of the following is an intermediate acting non-depolarizing neuromuscular blocking agent?

Pancuronium. **Explanation:** The classification of non-depolarizing neuromuscular blocking agents (NMBAs) is primarily based on their duration of action. **Correct Answer: A. Pancuronium** Pancuronium is a long-acting steroid-based NMBA. It typically has a duration of action exceeding 60–90 minutes. It is primarily excreted by the kidneys and is known for its vagolytic effect, which can cause tachycardia. **Analysis of Incorrect Options:** * **B. Vecuronium:** This is an **intermediate-acting** agent (duration 30–45 minutes). It is an analogue of pancuronium but lacks the vagolytic effects and is primarily metabolized by the liver. * **C. Rocuronium:** This is also an **intermediate-acting** agent. It is unique due to its rapid onset of action (60–90 seconds), making it the drug of choice for Rapid Sequence Induction (RSI) when Succinylcholine is contraindicated. * **D. Atracurium:** This is an **intermediate-acting** benzylisoquinolone. It is notable for undergoing **Hofmann elimination** (spontaneous degradation at body temperature and pH), making it safe for patients with renal or hepatic failure. **High-Yield Clinical Pearls for NEET-PG:** * **Long-acting:** Pancuronium, Doxacurium, Pipecuronium. * **Intermediate-acting:** Vecuronium, Rocuronium, Atracurium, Cisatracurium. * **Short-acting:** Mivacurium (metabolized by plasma cholinesterase). * **Ultra-short acting:** Succinylcholine (the only depolarizing agent used clinically). * **Drug of Choice in Renal Failure:** Cisatracurium (least histamine release and undergoes Hofmann elimination). * **Reversal Agent:** Sugammadex is a specific reversal agent for the steroidal NMBAs (Rocuronium > Vecuronium > Pancuronium).

Question 1

What is the formula for transthoracic compliance?

Accepted Answer

C = V / (Alv p - atmospheric pressure)

Answer

C = Vt x RR / PEEP

Answer

C = Vt / (Pplt - PEEP)

Answer

C = Vt / (Pk - Pplt)

Question 2

Which artery is most commonly cannulated for invasive blood pressure monitoring?

Accepted Answer

Radial artery

Answer

Femoral artery

Answer

Carotid artery

Answer

Ulnar artery

Question 3

A patient weighing 80 kg is in shock. Calculate the infusion rate in drops per minute required for a vasopressor. The vial contains 200 mg in 5 ml. The drug is diluted in 250 ml Normal Saline. The recommended dose is microgram/kg/min. Assume 16 drops equal 1 ml.

Accepted Answer

8

Answer

16

Answer

24

Answer

32

Question 4

Clayton is used in a closed breathing system for what purpose?

Accepted Answer

As an indicator

Answer

As a hardener

Answer

As an absorbent

Answer

As a softener

Question 5

What does MAC stand for in anesthesiology?

Accepted Answer

Minimum alveolar concentration

Answer

Minimal analgesic concentration

Answer

Minimal anesthetic concentration

Answer

Maximum alveolar concentration

Question 6

Neostigmine is used for reversing the adverse effect of which of the following anesthetic agents?

Accepted Answer

Dextrocucurium and pancuronium

Answer

Dextrocucurium alone

Answer

Alcuronium alone

Answer

Ketamine complications

Question 7

For central venous pressure monitoring, all are true except?

Accepted Answer

Pulmonary capillary wedge pressure normally is 10-20 mmHg.

Answer

Internal jugular vein is the preferred site.

Answer

Indicated for monitoring fluid status.

Answer

A Swan-Ganz catheter entering the pulmonary artery shows a dicrotic notch.

Question 8

Air embolism is best diagnosed by which of the following?

Accepted Answer

Doppler study

Answer

End tidal CO2

Answer

End tidal N2

Answer

Ultrasound

Question 9

Arrange the following parts of an anesthesia machine in increasing order of pressure system:

Accepted Answer

Flow indicators, Vaporizer mounting devices, Pipeline indicator, Hanger yoke assembly

Answer

Vaporizer mounting devices, Pipeline indicator, Flow indicators, Hanger yoke assembly

Answer

Hanger yoke assembly, Vaporizer mounting devices, Flow indicators, Pipeline indicator

Answer

Flow indicators, Pipeline indicator, Hanger yoke assembly, Vaporizer mounting devices

Question 10

Which of the following is an intermediate acting non-depolarizing neuromuscular blocking agent?

Accepted Answer

Pancuronium

Answer

Vecuronium

Answer

Rocuronium

Answer

Atracurium

Anesthetic Equipment and Monitoring — MCQs

Anesthetic Equipment and Monitoring — MCQs

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