Principles of Anesthesia Machine cont'd

Question 1

What is vapor pressure?

Answer 1

The pressure that a vapor exerts above the liquid in a closed container.

Question 2

Explain Latent heat of vaporization.

Answer 2

When liquid evaporates, it loses heat.

Question 3

What does it mean when Sevo = 2%? What does this mean for FiO2?

Answer 3

2 parts Sevo per 100 parts of gas. For FiO2, this means that if it is 100% entering the vaporizer, it will be 98% exiting the vaporizer.

Question 4

Which of the volatile agents is not variable bypass?

Answer 4

Desflurane: this gas enters the fresh gas flow. The conc on the dial is the conc entering the FGF.

Question 5

If there was a leak in the bellows while the ventilator is turned on; what would be the effect?

Answer 5

• Higher than expected peak inspiratory pressure (PIP)

- Higher than expected FiO2

Question 6

In ascending bellows, if there is a leak what will happen to the bellows?

Answer 6

They will collapse.

Question 7

What are the units of pulmonary compliance?

Answer 7

mL/cmH2O

Question 8

Pulmonary Compliance Equation:

Answer 8

C = change Volume / change Pressure

Question 9

Examples of compliant lungs:

Answer 9

COPD, smokers

- lungs expand great but deflate slowly (air gets trapped in alveoli)

Question 10

Non-compliant lungs:

Answer 10

Acute respiratory distress syndrome

- hard to get air in but easy to get air out

Question 11

What is the point of PEEP (positive end expiratory pressure)?

Answer 11

To prevent atelectasis.

Question 12

Common uses for CPAP

Answer 12

• sleep apnea patients
• patients who are intubated for prolonged periods
• Intubated patients undergoing lung surgery (can deliver O2 to the operated lung w/o expanding it)
• Preoxygenation in obese patients (APL valve slightly closed during preoxygenation)