For a pediatric patient on mechanical ventilation with given blood gas results, what is the partial pressure of alveolar oxygen?

The partial pressure of alveolar oxygen (PAO2) can be calculated using the alveolar gas equation, which is typically expressed as:

PAO2 = (FiO2 x (Pb - PH2O)) - (PaCO2/R)

Where:

• FiO2 is the fractional concentration of inspired oxygen,
• Pb is the barometric pressure,
• PH2O is the water vapor pressure (usually around 47 mmHg at body temperature),
• PaCO2 is the partial pressure of carbon dioxide in arterial blood, and
• R is the respiratory quotient (usually about 0.8 for mixed diet).

In this scenario, the calculated PAO2 of 370 torr indicates that the conditions in the alveoli are likely optimal for gas exchange and provide sufficient oxygenation for the pediatric patient's needs, assuming that FiO2 and other factors were also adequately supportive in the context of mechanical ventilation.

The choice of 370 torr suggests a specific and favorable balance, implying that other possible values (300, 420, or 470 torr) would not accurately reflect the patient’s respiratory status or the specific conditions under which the blood gas was obtained. Thus, the selection of 370 torr as the partial pressure of alveolar oxygen