Anesthetic Equipment and Monitoring Practice Questions

Q: A patient selected for surgery was induced with Thiopentone iv through one of the antecubital veins and complained of severe pain of the whole hand. The next line of management is:

IV lignocaine through same needle. **_IV lignocaine through same needle_** - **Lignocaine** (lidocaine) is a **local anesthetic** that can alleviate the severe pain caused by the extravasation or intra-arterial injection of thiopentone by **vasodilatation** and nerve block. - This immediate intervention helps to mitigate the consequences of thiopentone injection outside the vein or into an artery, which can include **vasoconstriction**, tissue necrosis, and **compartment syndrome**. *Leave it alone* - Ignoring the patient's complaint of severe pain, especially after thiopentone administration, could lead to **severe tissue damage**, including **vasoconstriction**, necrosis, and potential limb loss. - Doing nothing is a **negligent approach** that fails to address a potentially serious complication of intravenous drug administration. *IV ketamine through same needle* - **Ketamine** is a dissociative anesthetic and analgesic, but it is not the primary drug for managing local pain and potential vascular complications from thiopentone extravasation or intra-arterial injection. - Administering ketamine in this scenario would **not address the underlying vascular injury** or tissue irritation caused by thiopentone and might only mask the pain without resolving the issue. *Give IV propofol through same needle* - **Propofol** is an intravenous anesthetic that generally causes less pain on injection than thiopentone and has some vasodilatory properties, but it is not the immediate or primary treatment for managing the severe pain and potential vascular injury caused by thiopentone outside the vein or in an artery. - While it may offer some comfort, propofol does not have the **specific local anesthetic action** or immediate **vasodilatory effect** needed to reverse the harmful effects of thiopentone in this situation.

Q: A 20-year old spontaneous breathing patient undergoing incision and drainage under GA, which of the following is the breathing circuit of choice for spontaneous ventilation?

Mapleson A. ***Mapleson A*** - The **Mapleson A circuit (Magill circuit)** is the most efficient scavenging system for **spontaneous ventilation** due to the fresh gas flow being located near the patient and the APL valve downstream. - This arrangement allows exhaled CO2 to be flushed out easily during expiration with minimal fresh gas flow, preventing rebreathing. *Mapleson C* - The Mapleson C circuit is similar in design to Mapleson B but with a shorter corrugated tube, making it **less efficient for spontaneous ventilation** due to increased rebreathing. - It is often used for **transport** or in resuscitation kits but is not the circuit of choice for routine spontaneous breathing under general anesthesia. *Mapleson D* - Mapleson D circuits, particularly the **Bain circuit** (a coaxial modification), are efficient for both **controlled and spontaneous ventilation**, but they are **most efficient for controlled ventilation**, which is not the primary mode described in the question. - For spontaneous ventilation, it requires a higher fresh gas flow rate (2-3 times minute ventilation) to prevent CO2 rebreathing compared to Mapleson A. *Mapleson B* - The Mapleson B circuit is **less efficient for spontaneous ventilation** due to the fresh gas inlet and APL valve being close to the patient, leading to significant rebreathing of CO2 unless very high fresh gas flows are used. - It is generally considered **inefficient** for both spontaneous and controlled ventilation compared to other Mapleson circuits.

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: A patient on atracurium develops seizures due to accumulation of

Laudanosine. ***Laudanosine*** - **Laudanosine** is a metabolite of atracurium which is known to cross the **blood-brain barrier** and can cause **seizures** and central nervous system excitation, especially in high concentrations or in patients with impaired renal or hepatic function. - Atracurium undergoes **Hofmann elimination** and **ester hydrolysis** to produce laudanosine and other inactive metabolites. *Sulfated Atracurium* - **Atracurium** is not primarily metabolized through sulfation; its primary degradation pathways are **Hofmann elimination** and **ester hydrolysis**. - There is no known direct association between sulfated atracurium and seizure activity. *Hofmann elimination products* - **Hofmann elimination** is one of the main pathways for atracurium degradation, but the *overall products* are numerous, and **laudanosine** is the specific metabolite implicated in seizures. - While laudanosine is a product of Hofmann elimination, this option is too broad and does not pinpoint the neurotoxic metabolite. *Ester hydrolysis products* - **Ester hydrolysis** is another significant pathway for atracurium metabolism, but, similar to Hofmann elimination, it produces various metabolites. - **Laudanosine** is formed via Hofmann elimination; ester hydrolysis primarily produces quaternary acid and alcohol products, which are not directly linked to seizure activity.

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.

Question 1

A patient selected for surgery was induced with Thiopentone iv through one of the antecubital veins and complained of severe pain of the whole hand. The next line of management is:

Accepted Answer

IV lignocaine through same needle

Answer

Leave it alone

Answer

IV ketamine through same needle

Answer

Give IV propofol through same needle

Question 2

A 20-year old spontaneous breathing patient undergoing incision and drainage under GA, which of the following is the breathing circuit of choice for spontaneous ventilation?

Accepted Answer

Mapleson A

Answer

Mapleson C

Answer

Mapleson D

Answer

Mapleson B

Question 3

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 4

As per ISO, color of N2O cylinder is –

Accepted Answer

Blue

Answer

Black

Answer

White

Answer

Red

Question 5

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 6

Depth of anaesthesia can be best assessed by

Accepted Answer

Bispectral index

Answer

ABG analysis

Answer

Pulse oximeter

Answer

End tidal Pco2

Question 7

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

Accepted Answer

Propane

Answer

Acetylene

Answer

Natural gas

Answer

Hydrogen

Question 8

A patient on atracurium develops seizures due to accumulation of

Accepted Answer

Laudanosine

Answer

Sulfated Atracurium

Answer

Hofmann elimination products

Answer

Ester hydrolysis products

Question 9

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 10

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

Anesthetic Equipment and Monitoring — MCQs

Anesthetic Equipment and Monitoring — MCQs

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