Anesthetic Techniques & Equipment Usage Flashcards

During stable mechanical ventilation, ETCO2 drops abruptly from 38 to 18 mmHg and severe hypotension develops. What is the most likely cause?

Answer: Massive pulmonary embolism or sudden low cardiac output

A sudden fall in ETCO2 without a ventilation change reflects reduced pulmonary perfusion, such as from an embolism or cardiovascular collapse.

A capnogram baseline no longer returns to zero during inspiration. What are the most likely causes?

Answer: Exhausted CO2 absorbent or an incompetent unidirectional valve

Inspired CO2 means the patient is rebreathing exhaled gas because of absorbent failure or a valve fault.

A patient given high-dose benzocaine spray has cyanosis and an SpO2 that plateaus near 85% despite 100% oxygen. What is the most likely diagnosis?

Answer: Methemoglobinemia

Methemoglobin absorbs light equally at 660 and 940 nm, which drives the pulse oximetry reading toward about 85%.

How does carboxyhemoglobin affect a standard two-wavelength pulse oximeter reading?

Answer: SpO2 falsely high

Carboxyhemoglobin absorbs 660 nm light much like oxyhemoglobin, so SpO2 overestimates true oxygen saturation.

Which BIS range is generally targeted for adequate general anesthesia?

Answer: 40-60

BIS values of 40-60 are associated with a low probability of awareness without excessive anesthetic depth.

Quantitative neuromuscular monitoring shows a train-of-four ratio of 0.7. What does this indicate?

Answer: Residual neuromuscular blockade; recovery is inadequate

Adequate recovery requires a train-of-four ratio of at least 0.9, so 0.7 shows clinically significant residual weakness.

An underdamped arterial line system will most likely do which of the following?

Answer: Overestimate systolic pressure

Underdamping or resonance causes overshoot, which exaggerates systolic and lowers diastolic readings while mean pressure stays relatively accurate.