Water SVP 6.3 kPa at 37°C — FRCA Primary MCQ

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ModeratePhysics & Clinical MeasurementWater SVP 6.3 kPa at 37°CFRCA Primary

Regarding the partial pressure of water vapour in fully saturated gas at 37°C the value is approximately:

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Correct answer: C — 6.3 kPa

Saturated vapour pressure of water at 37°C is 6.3 kPa (47 mmHg). This is important in the alveolar gas equation: PAO2 = FiO2 × (Patm - PH2O) - PaCO2/R. Inspired gas is fully humidified and warmed to body temperature by the time it reaches the carina. The SVP of water increases with temperature.

Reference: Al-Shaikh Stacey 2019 Essentials of Anaesthetic Equipment