Question

A 37-year-old woman is on a volume cycled ventilator on a day when the barometric pressure is 745 mm Hg. The patient is receiving an FiO2 of 0.50. The following clinical data are obtained:

Hb: 11 g%

PaO2 60 torr (SaO2 = 90%)

PVO2 35 torr (SVO2 = 65%)

PaCO2 38 torr

Cardiac Output 38 torr

Based on this information, calculate the patient's

Total Oxygen Delivery

Arterial-venous oxygen content difference

Intrapulmonary shunting

Oxygen consumption

Oxygen extraction ratio

Answer 1

1. Total oxygen delivery: ( Hgb × 1.36 × SaO2) + ( 0.0031 × PaO2)
= (11×1.36×90) + (0.0031×60) = 1346.4 + 0.186 = 1346.586
Ans: 13.6 ml O2 / 100 ml
2. Arterial venous oxygen content difference (Ca-vO2) : CaO2 - CvO2
CaO2 = (Hb ×1.36) (SaO2)/100 + (PaO2×0.0031) = (11×1.36) (90/100) + (60×0.0031) = (14.96)(0.9) + 0.186 = 13. 464 + 0.186 = 13.65
CvO2 = (Hb×1.36) (SvO2)/100 + (PvO2 × 0.0031) = (11×1.36)(65/100) + (35×0.0031) = (14.96)(0.65) + 0.1085 = 9.724 + 0.1085 = 9.8325
Ca-vO2: CaO2 - CvO2= 13.65 – 9.8325 = 3.8175
Ans: 3.8 ml/ dl
3. Oxygen consumption (VO2) = CO × Ca - vO2 × 10 = 38 × 3.8× 10 = 1.4 ml/min
4. Oxygen extraction ratio = VO2 / DO2 = (SaO2-SvO2) / SaO2 = (90-65) / 90 = 25/90= 0.27