RespCARE 203 Practice Worksheet: Humidity, Alveolar Gas, IBW, and Ventilation (Vocabulary Flashcards)

Vocabulary flashcards covering humidity concepts (absolute humidity, water vapor pressure, humidity deficit), the alveolar gas equation and PAO2, respiratory ventilation concepts (FiO2, PB, PaCO2, R), IBW calculations, and basic hypoxemia/hyperventilation concepts referenced in the Practice Worksheet.

Absolute Humidity (AH)

The maximum amount of water vapor air can hold at a given temperature, measured in mg/L; at body temperature it is about 44 mg/L.

Water Vapor Pressure (PH2O) at body temperature

Saturated water vapor pressure at 37°C, approximately 47 torr.

Humidity Deficit

The difference between the humidity needed to saturate inspired air at 37°C (about 44 mg/L at 100% RH) and the actual humidity of the inspired gas.

Alveolar Gas Equation

Equation used to estimate alveolar oxygen tension: PAO2 = FiO2 × (PB − PH2O) − (PaCO2 / R) (in the notes, PB is Pbar, PH2O is 47, R is 0.8).

PAO2 (Alveolar Oxygen Tension)

An estimate of the oxygen partial pressure in the alveoli; used to assess oxygen exchange.

FiO2 (Fraction of Inspired Oxygen)

The fraction or percentage of oxygen in the inspired gas (e.g., 0.21 in room air).

Barometric Pressure (Pbar)

Atmospheric pressure used in the alveolar gas equation; in the notes, Pbar = 800 mmHg.

PaCO2 (Partial Pressure of CO2 in Blood)

The arterial CO2 partial pressure; normal ~40 mmHg, lower values indicate hyperventilation.

Respiratory Quotient (R)

The ratio of CO2 produced to O2 consumed; typically about 0.8 in healthy individuals and used in the alveolar gas equation.

Ideal Body Weight (IBW)

An estimate of healthy body weight based on height and sex; formulas differ for male and female.

IBW for Female

Female: 45.5 + 2.3 × (Height in inches − 60). For 5'6" (66 in), IBW ≈ 59.3 kg.

Tidal Volume (VT)

The volume of air moved per breath; in the notes, 300 mL.

Respiratory Rate (RR)

Breaths per minute; in the scenario, RR = 32.

Minute Ventilation (VE)

Total air moved in or out of the lungs per minute; VE = RR × VT; with RR 32 and VT 0.3 L, VE ≈ 9.6 L/min.

Hypoxemia

Low arterial oxygen; commonly defined as PaO2 < 80 mmHg or SpO2 < 90% depending on context (the patient’s PaO2 of 56 mmHg indicates hypoxemia).

Hyperventilation

Increased ventilation often resulting in low PaCO2; in the notes, RR of 32 with PaCO2 of 32 mmHg indicates hyperventilation.

SpO2 (Peripheral Oxygen Saturation)

O2 saturation measured noninvasively; in the case, SpO2 = 89% on room air indicates hypoxemia.