Anesthetic Equipment and Monitoring Practice Questions

Q: Amount of water that constitutes soda lime in carbon dioxide absorber is

14-19%. ***14-19%*** - **Soda lime** typically contains **14-19% water** by weight, which acts as a crucial catalyst in the chemical reaction with carbon dioxide. - The presence of water is essential for the **hydration of calcium hydroxide** and the formation of **carbonic acid**, facilitating CO2 absorption. *25-30%* - This percentage of water is **too high** for optimal soda lime function, potentially leading to a slushy consistency or **reduced CO2 absorption efficiency**. - Excess water can also increase the risk of **dusting** and airway irritation. *10-14%* - While closer, this range represents slightly **less than optimal water content**, which could lead to **slower CO2 absorption** rates. - Insufficient water might also decrease the overall **absorbent capacity** of the soda lime. *20-24%* - This water content is **higher than the ideal range** and could negatively impact the performance of soda lime by compromising its granular structure. - It might also contribute to **channeling** within the absorber, reducing efficient CO2 removal.

Q: What causes sudden decreased end tidal CO2 in GA?

Cardiac arrest. ***Cardiac arrest*** - In **cardiac arrest**, there is a sudden cessation of effective **cardiac output**, which leads to a dramatic reduction in pulmonary blood flow. - As a result, **CO2 is not transported to the lungs** for exhalation, causing an abrupt and severe drop in **end-tidal CO2**. *Pulmonary embolism* - A **pulmonary embolism** causes an acute obstruction of pulmonary arterial blood flow, leading to an **increase in alveolar dead space**. - While it can decrease **end-tidal CO2** due to reduced perfusion, the drop is often less sudden and complete than in cardiac arrest, and the primary mechanism is **ventilation-perfusion mismatch**. *Pulmonary hypertension* - **Pulmonary hypertension** involves chronically elevated pressures in the pulmonary arteries, which can lead to **right ventricular dysfunction** and reduced cardiac output over time. - It typically causes a more gradual and chronic reduction in **end-tidal CO2** due to impaired gas exchange, rather than a sudden, precipitous drop. *Malignant hyperthermia* - **Malignant hyperthermia** is characterized by a rapid and severe increase in **metabolic rate** and CO2 production. - This condition typically leads to a **sudden increase in end-tidal CO2** as the body produces more CO2 than can be eliminated, rather than a decrease.

Q: What is the pin index of O2-CO2 (CO2 < 7.5%)?

1,6. ***1,6*** - The pin index system for medical gases helps ensure the correct gas is connected to the appropriate equipment. For **O2-CO2 mixtures with CO2 less than 7.5%**, the pin index is **1,6**. - This specific pin configuration prevents accidental administration of the wrong gas mixture, ensuring patient safety. *2,6* - This pin index configuration is typically associated with **medical air**, which is a mixture of nitrogen and oxygen, not an O2-CO2 mixture. - Using the wrong pin index could lead to connecting a medical air cylinder to an O2-CO2 port, potentially causing inappropriate gas delivery. *3,6* - This pin index configuration is designated for **nitrous oxide**. - Connecting a nitrous oxide cylinder to an O2-CO2 port would be a severe medical error, as these gases have very different clinical applications and effects. *4,6* - This pin index corresponds to **carbon dioxide (CO2)** when it is supplied as a pure gas or in higher concentrations. - While O2-CO2 mixtures contain CO2, the specific pin index 4,6 is not used for mixtures with CO2 less than 7.5%, distinguishing it for pure CO2 applications.

Q: Ideal anaesthetic circuit for spontaneously breathing pediatric patient is:-

Magills circuit. ***Magills circuit*** - This is a **Mapleson A** system, which is the most efficient for spontaneously breathing patients due to its ability to prevent rebreathing and minimize fresh gas flow requirements. - While pediatric patients are often managed with other circuits due to anatomical and physiological considerations, the Magill circuit's design makes it theoretically ideal for spontaneous breathing in any patient. *Bains circuit* - The Bain circuit is a **Mapleson D** system, which is more suited for controlled ventilation rather than spontaneous breathing due to its configuration. - While it offers advantages like warmth and humidification, its efficiency for spontaneous breathing is lower, often requiring higher fresh gas flows to prevent rebreathing. *Jackson rees circuit* - The Jackson Rees modification is a type of **Mapleson F** circuit, which is an adaptation of the Ayre's T-piece. It is commonly used in pediatrics due to its low resistance and suitability for both spontaneous and controlled ventilation. - However, for *spontaneous breathing*, it is less efficient than the Magill circuit in terms of fresh gas flow requirements, as it relies on a high fresh gas flow to flush exhaled gases. *Mapleson D* - The Mapleson D circuit is efficient for **controlled ventilation** due to the position of the fresh gas inlet near the patient and a long expiratory limb with a reservoir bag and APL valve at the machine end. - For spontaneous breathing, it is less efficient than a Mapleson A circuit (like the Magill), as higher fresh gas flows are required to prevent rebreathing of exhaled CO2.

Q: Which of the following is not a cardiovascular monitoring technique

Capnography. ***Capnography*** - **Capnography** is primarily used to monitor **ventilatory status** by measuring the concentration of carbon dioxide in respiratory gases. - While respiratory and cardiovascular systems are interconnected, capnography directly assesses **pulmonary function** and **CO2 elimination**, not intrinsic cardiovascular hemodynamics. *Transesophageal echocardiography* - **Transesophageal echocardiography (TEE)** provides detailed images of the heart's structure and function, including valve function, chamber size, and myocardial contractility. - It is a direct and highly effective method for **cardiovascular assessment** and monitoring during surgical procedures or in critically ill patients. *Pulmonary artery catheterization* - **Pulmonary artery catheterization (PAC)**, also known as Swan-Ganz catheter, directly measures pressures within the right atrium, right ventricle, and pulmonary artery, as well as cardiac output. - This technique provides comprehensive **hemodynamic data** essential for cardiovascular monitoring in critical care settings. *Central venous pressure monitoring* - **Central venous pressure (CVP) monitoring** measures the pressure in the vena cava or right atrium, reflecting the patient's **fluid status** and right ventricular preload. - It is a key parameter for assessing circulatory volume and guiding fluid management in patients with cardiovascular instability.

Q: Capnography is useful for

Determining the appropriate placement of endotracheal. ***Determining the appropriate placement of endotracheal*** - Capnography provides a direct and continuous measurement of **exhaled CO2**, which confirms proper **endotracheal tube (ETT) placement** in the trachea. - The presence of a square-wave capnogram with a distinct end-tidal CO2 (ETCO2) value indicates CO2 detection, confirming the ETT is in the airway and not the esophagus. *Determining Vaporizer malfunction or contamination* - **Anesthetic gas analyzers**, not capnographs, are used to detect vaporizer malfunctions or contamination by measuring the concentration of specific anesthetic agents. - While a capnograph might show changes in CO2 if ventilation is affected by an issue with the vaporizer, it does not directly diagnose the vaporizer problem itself. *Determining circuit hypoxia* - **Oxygen analyzers** in the anesthetic circuit are used to determine the concentration of oxygen, which helps detect circuit hypoxia. - Capnography monitors CO2 levels, and while changes in CO2 might indirectly result from hypoxia, it doesn't directly measure oxygen concentration or alert to hypoxia. *Detecting concentration of oxygen in the anesthetic circuit.* - **Oxygen sensors or galvanic cells**, integrated into the anesthesia machine, are specifically designed to measure the inspired oxygen concentration. - Capnography measures carbon dioxide, not oxygen, and therefore cannot directly assess the oxygen levels within the anesthetic circuit.

Q: Sodalime circuit is not used in anaesthesia with:

Trichloroethylene. ***Trichloroethylene*** - **Trichloroethylene** reacts with **sodalime** to produce **dichloroacetylene**, which is neurotoxic and can cause cranial nerve palsies due to heat generation. - Due to this hazardous interaction, trichloroethylene is strictly contraindicated for use in a **sodalime circuit**. *Enflurane* - While enflurane can undergo some degradation by sodalime at high temperatures to form **Compound A**, this effect is much less significant compared to trichloroethylene. - The level of Compound A formed with enflurane in a sodalime circuit is generally considered clinically insignificant under normal operating conditions. *Methoxyflurane* - **Methoxyflurane** reacts with sodalime to produce **nephrotoxic compounds** like fluoride and oxalic acid, which can cause high-output renal failure. - Despite this, its reaction with sodalime is different from the neurotoxic products formed with trichloroethylene. *Isoflurane* - **Isoflurane** is comparatively stable in the presence of sodalime and shows minimal degradation. - It does not produce significant toxic byproducts when used in a sodalime circuit, making it a safe choice.

Q: What is the PIN index number for nitrous oxide?

3-4. ***3-4*** - The **pin index safety system** is a safety feature on anesthetic gas cylinders and equipment, with **nitrous oxide** specifically corresponding to pins in positions 3 and 4. - This configuration ensures that a nitrous oxide cylinder can only be fitted to equipment designed for nitrous oxide, preventing the accidental administration of the wrong gas. *3-5* - This pin index combination does not correspond to a standard medical gas cylinder, indicating a mismatch in the safety system. - Correct identification of pin indices is crucial for patient safety in anesthesia and respiratory care. *2-5* - This pin index combination is used for **air**, not nitrous oxide. - Each medical gas has a unique pin position to prevent errors in gas delivery. *3-6* - This pin index combination does not correspond to any standard medical gas cylinder, highlighting an incorrect identification within the safety system. - The precise arrangement of pins is a critical safeguard against gas mix-ups. *2-6* - This pin index combination is used for **oxygen**, not nitrous oxide. - The pin index system is a physical safety mechanism designed to prevent the connection of an incorrect gas cylinder to the corresponding gas-specific yoke.

Q: Anaesthetic circuit that prevents rebreathing of CO2 –

Circle system. ***Circle system*** - The **circle system** incorporates a **carbon dioxide absorber** (soda lime or barium hydroxide lime) which chemically removes CO2 from exhaled gases, preventing rebreathing. - It uses both inspiratory and expiratory limbs with one-way valves to ensure unidirectional flow of gases through the CO2 absorber and to the patient. *Ayre's piece* - This is a modification of the **Mapleson F (Jackson-Rees) circuit** and is a non-rebreathing system for pediatric use. - It **prevents rebreathing** by having high fresh gas flow but does not contain a CO2 absorber. *Mapleson D circuit* - The **Mapleson D circuit** prevents rebreathing by using a high fresh gas flow to flush exhaled gases out of the system, not via a CO2 absorber. - It is classified as an **open non-rebreathing system** and effectively prevents CO2 rebreathing if fresh gas flow is sufficient (typically 2-3 times minute ventilation). *Magill's circuit* - The **Magill's circuit** (Mapleson A) is designed to prevent rebreathing at fresh gas flows approximately equal to minute ventilation, but it relies on separating fresh gas flow from exhaled gas, not CO2 absorption. - Rebreathing can occur if the fresh gas flow is not adequate or if there is insufficient emptying of the reservoir bag during expiration.

Question 1

Amount of water that constitutes soda lime in carbon dioxide absorber is

Accepted Answer

14-19%

Answer

25-30%

Answer

10-14%

Answer

20-24%

Question 2

What causes sudden decreased end tidal CO2 in GA?

Accepted Answer

Cardiac arrest

Answer

Pulmonary embolism

Answer

Pulmonary hypertension

Answer

Malignant hyperthermia

Question 3

Bernoulli's theorem explains -

Accepted Answer

Venturi effect in oxygen delivery systems

Answer

Airflow turbulence in stenotic airways

Answer

Vocal cord adduction during inspiration

Answer

Pressure changes in pleural space

Question 4

What is the pin index of O2-CO2 (CO2 < 7.5%)?

Accepted Answer

1,6

Answer

2,6

Answer

3,6

Answer

4,6

Question 5

Ideal anaesthetic circuit for spontaneously breathing pediatric patient is:-

Accepted Answer

Magills circuit

Answer

Bains circuit

Answer

Jackson rees circuit

Answer

Mapleson D

Question 6

Which of the following is not a cardiovascular monitoring technique

Accepted Answer

Capnography

Answer

Transesophageal echocardiography

Answer

Pulmonary artery catheterization

Answer

Central venous pressure monitoring

Question 7

Capnography is useful for

Accepted Answer

Determining the appropriate placement of endotracheal

Answer

Determining Vaporizer malfunction or contamination

Answer

Determining circuit hypoxia

Answer

Detecting concentration of oxygen in the anesthetic circuit.

Question 8

Sodalime circuit is not used in anaesthesia with:

Accepted Answer

Trichloroethylene

Answer

Enflurane

Answer

Methoxyflurane

Answer

Isoflurane

Question 9

What is the PIN index number for nitrous oxide?

Accepted Answer

3-4

Answer

3-5

Answer

2-5

Answer

3-6

Answer

2-6

Question 10

Anaesthetic circuit that prevents rebreathing of CO2 –

Accepted Answer

Circle system

Answer

Ayre's piece

Answer

Mapleson D circuit

Answer

Magill's circuit

Anesthetic Equipment and Monitoring — MCQs

Anesthetic Equipment and Monitoring — MCQs

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