ABG Interpretation questions with correct answers

The following blood gas measurements determines how well a patients lungs are being ventilated. - Answer PaCO2 The following blood gas measurements determines the level of tissue oxygenation. - Answer PvO2: Normal value 35 - 45 mmHg. A decreased PvO2 indicates inadequate oxygenation of the tissues most commonly caused by a decreased cardiac output. As cardiac output drops, blood flow to the tissues slows while tissue oxygen uptake remains at the same rate. Therefore, some tissues take more oxygen from the blood than normal, which deprives other tissues of the normal amount of oxygen. When the blood returns from the body to the pulmonary artery, it contains less oxygen that it should and is reflected by a drop in PvO2. A patient using an aerosol mask set at 40% oxygen pH 7.42, PaCO2 36, PaO2 122, HCO3 What is the A-a gradient? PB = 747 - Answer PAO2 = (PB - 47)FiO2 - (PaCO2 * 1.25) A-a Shortcut for PAO2 = (7 * O2%) - (PaCO2 + 10) (700 * 0.40) - (36 + 10) = 234 A-a = 234 - 122 = 112