Anesthetic Equipment and Monitoring Practice Questions

Q: As per ISO, color of N2O cylinder is –

Blue. ***Blue*** - According to **ISO standards**, the medical gas cylinder for **Nitrous Oxide (N2O)** is uniformly identified by a **blue body**. - This color coding helps in immediate visual recognition to ensure the correct gas is used in medical settings, preventing administration errors. *Black* - A **black cylinder** typically indicates **Nitrogen (N2)** according to ISO standards for medical gases. - Using a black cylinder for nitrous oxide would be a severe error, leading to the administration of the wrong gas. *White* - A **white cylinder** is commonly used for **Oxygen (O2)** as per ISO conventions for medical gas cylinders. - Administering oxygen instead of nitrous oxide would, while not directly harmful, prevent the intended anesthetic or analgesic effect. *Red* - A **red cylinder** is generally used for **Medical Air** in some regions, though it can vary based on local regulations. - In many settings, red can also denote **flammable gases** or **fire-fighting equipment**, making it unsuitable for nitrous oxide.

Q: Depth of anaesthesia can be best assessed by

Bispectral index. ***Bispectral index*** - The **Bispectral Index (BIS)** monitor processes **electroencephalogram (EEG)** signals to provide a numerical value (0-100) indicating the **level of consciousness** and hypnotic depth during anesthesia. - A lower BIS value (typically 40-60) indicates a deeper anesthetic state, helping clinicians avoid **awareness during surgery** and guide anesthetic agent delivery. *ABG analysis* - **Arterial Blood Gas (ABG)** analysis measures parameters like pH, PCO2, PO2, and bicarbonate, reflecting the patient's **acid-base balance** and **oxygenation**. - While important for overall physiological status, ABG analysis does not directly assess the **depth of anesthesia** or the patient's level of consciousness. *Pulse oximeter* - A **pulse oximeter** measures **oxygen saturation (SpO2)** and heart rate, reflecting the adequacy of oxygen delivery. - It does not provide information about the **depth of consciousness** or the hypnotic effect of anesthetic agents. *End tidal Pco2* - **End-tidal PCO2 (EtCO2)** monitors the partial pressure of carbon dioxide at the end of exhalation, providing an indication of **ventilation** and CO2 elimination. - While EtCO2 is crucial for managing ventilation during anesthesia, it does not directly reflect the **depth of anesthesia** or the patient's neurological state.

Q: In medical applications, the best fuel gas when used with oxygen is:

Propane. ***Propane*** - **Propane** is the preferred fuel gas for medical applications when used with oxygen due to its **clean-burning properties** and **controlled flame temperature**. - It produces a **consistent, high-temperature flame** suitable for various medical procedures, including cauterization and sterilization, with minimal residue. *Acetylene* - **Acetylene** burns at a very high temperature but produces a significant amount of **soot and carbon deposits**, making it less suitable for precise medical applications. - Its high reactivity and **instability** also pose safety concerns in a clinical environment. *Natural gas* - **Natural gas** is a clean-burning fuel but has a **lower flame temperature** compared to propane, which may not be sufficient for certain high-temperature medical procedures requiring rapid heating. - It also requires a **continuous supply line**, which can be less flexible than portable propane tanks in a medical setting. *Hydrogen* - **Hydrogen** burns extremely cleanly and at a high temperature, but its **highly flammable nature** and the potential for **explosions** make it very dangerous for routine medical use. - The necessary safety precautions and specialized equipment for handling hydrogen are typically too complex and risky for standard clinical applications.

Q: All of the following cause a decrease in pulse oximeter readings except:

CarboxyHb. ***CarboxyHb*** - **Carboxyhemoglobin (COHb)** absorbs light similarly to oxyhemoglobin at 660 nm, causing the pulse oximeter to **overestimate oxygen saturation** rather than decrease the reading. - The pulse oximeter cannot differentiate between oxyhemoglobin and carboxyhemoglobin, leading to a falsely elevated or normal SpO2 reading despite **tissue hypoxia**. *MetHb* - **Methemoglobin (MetHb)** absorbs light equally at both 660 nm and 940 nm, causing the pulse oximeter reading to trend towards **85% regardless of the true arterial oxygen saturation**. - High levels of MetHb can lead to an artificially low or inaccurate SpO2 reading, reflecting a **functional hypoxemia**. *Hb-S, Hb-F* - **Hemoglobin S (HbS)** and **Hemoglobin F (HbF)**, when present in significant concentrations, can **interfere with accurate pulse oximetry readings**. - While not universally causing a direct decrease, their altered light absorption properties can lead to **inaccurate and often lower SpO2 values** compared to actual arterial oxygen content, particularly HbS which can aggregate. *Sulf-Hb* - **Sulfhemoglobin (SulfHb)** is a very rare form of hemoglobin that absorbs light uniquely at wavelengths measured by pulse oximeters, causing a **significant decrease in SpO2 readings**. - Sulfhemoglobinemia typically results in an SpO2 reading between **80-85%**, regardless of the actual oxygen saturation, similar to methemoglobin but with slightly different spectral properties.

Q: In anesthesia, fitting of wrong gas cylinder to the anesthesia machine can be prevented by:

Pin index system. ***Pin index system*** - The **pin index safety system** is a safety feature on anesthetic machines that ensures the correct gas cylinder is connected to the corresponding gas inlet. Each gas cylinder type has a unique pin configuration that only matches the specific yoke for that gas. - This system **prevents accidental connection** of a wrong gas cylinder, which could have serious patient safety implications. *Yoke assembly* - The **yoke assembly** is the component that holds the gas cylinder in place on the anesthesia machine. - While it's part of the connection, it's the **pin index system within the yoke** that provides the safety mechanism, not the yoke assembly itself. *Gas analyser* - A **gas analyzer** is used to measure the concentration of gases being delivered to the patient or exhaled by the patient during anesthesia. - It functions as a **monitoring device** and does not prevent the initial incorrect connection of a gas cylinder. *Bodok seal* - A **Bodok seal** is a type of washer often made of neoprene or nylon that provides a tight seal between the gas cylinder and the yoke assembly. - Its primary function is to **prevent gas leaks**, not to ensure that the correct type of gas cylinder is connected.

Q: Which of the following is NOT a rebreathing system used in anesthesia?

Mapleson F. ***Mapleson F*** - This system is known as the **Jackson-Rees modification** of the Mapleson T-piece and is a **non-rebreathing system** used primarily in pediatric anesthesia. - It features an **open-ended reservoir bag** attached to the expiratory limb, allowing for manual ventilation without rebreathing of expired gases if fresh gas flow is adequate. *Circle system* - The **circle system** is a common **rebreathing system** in anesthesia characterized by unidirectional valves and a CO2 absorber, allowing rebreathing of expired gases after CO2 removal. - It utilizes a **low fresh gas flow** to conserve anesthetic agents and moisture, making it a more economical and environmentally friendly choice. *To & fro system* - The **to & fro system** is an older type of **rebreathing system** that uses a soda lime canister placed directly in the breathing circuit, allowing exhaled gases to pass back and forth through it. - While effective for CO2 absorption, it is less commonly used now due to problems with heat buildup, airway resistance, and potential for caustic dust aspiration. *Water's system* - The **Water's system**, also known as the Waters-Dale system, is a type of **closed-circuit rebreathing system** that was also used for CO2 absorption. - It features a canister of CO2 absorbent placed close to the patient, enabling rebreathing of anesthetic gases.

Q: A 40–year female has to undergo incisional hernia surgery under general anaesthesia. She complains of awareness during her past cesarean section. Which of the following monitoring techniques can be used to prevent such awareness ?

Bispectral index monitoring. ***Bispectral index monitoring*** - **Bispectral Index (BIS) monitoring** is a technology that processes electroencephalogram (EEG) signals to provide a numerical value (0-100) indicating the patient's **level of consciousness or depth of anesthesia**. - A lower BIS value (typically 40-60) indicates a suitable depth of anesthesia for surgery, helping to prevent **intraoperative awareness**, especially in patients with a history of it. *Color doppler* - **Color Doppler** is an imaging technique used to visualize blood flow in vessels and assess the speed and direction of flow. - It is primarily used to diagnose conditions like **deep venous thrombosis**, *arterial stenosis*, or to evaluate blood flow to organs, and has no direct role in monitoring depth of anesthesia. *Transesophageal echocardiography* - **Transesophageal echocardiography (TEE)** is an invasive imaging technique that uses ultrasound from a probe inserted into the esophagus to provide detailed images of the heart. - TEE is critical for assessing **cardiac function**, *valvular heart disease*, or *aortic dissection* during surgery, but it does not monitor brain activity or the depth of anesthesia. *Pulse plethysmography* - **Pulse plethysmography** is a non-invasive method that measures changes in blood volume in a part of the body, often used to determine **heart rate** and assess peripheral perfusion. - While it is a component of pulse oximetry, it does not provide information about the **depth of anesthesia** or brain activity.

Q: Which nerve is used for monitoring anesthesia during surgery?

Ulnar. ***Ulnar*** - The **ulnar nerve** is commonly used for monitoring the depth of neuromuscular blockade during anesthesia due to its accessibility and predictable motor response. - Stimulation typically occurs at the wrist, and muscle contractions (twitches) in the **adductor pollicis muscle** are observed or measured. *Facial* - While the **facial nerve** can be used, it's generally reserved for procedures specifically involving the head and neck, as it can be less accessible and its responses may vary. - Monitoring the facial nerve often involves observing muscle contractions around the eye (**orbicularis oculi**) or mouth. *Radial* - The **radial nerve** is less commonly used for routine neuromuscular monitoring because its motor responses can be more variable and less easily isolated than the ulnar nerve. - Its stimulation can lead to complex movements, making quantitative assessment difficult. *Median* - Similar to the radial nerve, the **median nerve** is not the primary choice for routine neuromuscular monitoring due to potential for more diffuse muscle responses compared to the ulnar nerve. - Monitoring the median nerve would involve observing flexion of the fingers and thumb, which can be less precise for blockade assessment.

Question 1

True statement regarding pin index:

Accepted Answer

Oxygen cylinders have pins at positions 2 and 5, while nitrous oxide cylinders have pins at positions 3 and 5

Answer

Pin index safety system prevents misconnection of gas cylinders by using specific pin arrangements unique to each medical gas

Answer

Pin index system only applies to large H-size cylinders and is not used for smaller E-size portable cylinders

Answer

Pin index system is standardized internationally and mandated by regulatory bodies for all medical gas cylinders

Question 2

As per ISO, color of N2O cylinder is –

Accepted Answer

Blue

Answer

Black

Answer

White

Answer

Red

Question 3

What is defined as recovery index of the neuromuscular blocker (NMB):-

Accepted Answer

It is time interval between 25% and 75% twitch height of the NMB

Answer

It is time interval between 25% and 50% height of the NMB

Answer

It is time interval to reach 100% of twitch height of the NMB

Answer

It is time interval between 50% and 75% twitch height of the NMB

Question 4

Depth of anaesthesia can be best assessed by

Accepted Answer

Bispectral index

Answer

ABG analysis

Answer

Pulse oximeter

Answer

End tidal Pco2

Question 5

In medical applications, the best fuel gas when used with oxygen is:

Accepted Answer

Propane

Answer

Acetylene

Answer

Natural gas

Answer

Hydrogen

Question 6

All of the following cause a decrease in pulse oximeter readings except:

Accepted Answer

CarboxyHb

Answer

MetHb

Answer

Hb-S, Hb-F

Answer

Sulf-Hb

Question 7

In anesthesia, fitting of wrong gas cylinder to the anesthesia machine can be prevented by:

Accepted Answer

Pin index system

Answer

Yoke assembly

Answer

Gas analyser

Answer

Bodok seal

Question 8

Which of the following is NOT a rebreathing system used in anesthesia?

Accepted Answer

Mapleson F

Answer

Circle system

Answer

To & fro system

Answer

Water's system

Question 9

A 40–year female has to undergo incisional hernia surgery under general anaesthesia. She complains of awareness during her past cesarean section. Which of the following monitoring techniques can be used to prevent such awareness ?

Accepted Answer

Bispectral index monitoring

Answer

Color doppler

Answer

Transesophageal echocardiography

Answer

Pulse plethysmography

Question 10

Which nerve is used for monitoring anesthesia during surgery?

Accepted Answer

Ulnar

Answer

Facial

Answer

Radial

Answer

Median

Anesthetic Equipment and Monitoring — MCQs

Anesthetic Equipment and Monitoring — MCQs

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