Gas exchange — Flashcards

Flashcard 181: The alveolar gas equation states that the alveolar Po2 (PAo2) equals:_____

Answer: PAO2 = PIO2 – (PaCO2 / R)

Extra: PIO2 = inspired PO2; PaCO2 = arterial PCO2; R = respiratory quotient (usually 0.8).

Flashcard 182: Why must fetal hemoglobin have a much higher O2 binding affinity than HbA? _____

Answer: Drives O2 diffusion across placenta from mother to fetus

Flashcard 183: Blood in the umbilical vein has a O2 saturation of approximately _____%

Answer: 80

Flashcard 184: Carboxyhemoglobin causes _____ O2-binding capacity

Answer: decreased

Flashcard 185: Patients with cyanide poisoning have a _____ of the venous-arterial PO2 gradient

Answer: narrowing

Flashcard 186: The partial pressure of a gas (Px) in humidified tracheal air is equal to _____

Answer: (PB - PH2O) * F

Flashcard 187: How does normal aging change the A-a gradient?_____

Answer: Increased A-a gradient

Flashcard 188: Interstitial restrictive lung diseases are characterized by _____ A-a gradients

Answer: increased

Flashcard 189: What cause of hypoxemia is not greatly helped by supplemental O2?_____

Answer: Right-to-left shunt

Flashcard 190: Which zone of the lung has the highest Pao2? _____

Answer: Zone 1