Here is a sample of the answers for Chapter 12 of the Egan’s Workbook. For rest of the answers, check out our **Workbook Helper**. We have both the 10th and 11th Edition available.

**1.** Formula: PAO2 = (PB – PH2O) FiO2 – (PaCO2 ÷ 0.8) Solution: PAO2 = 713 × 0.21) 40 ÷ 0.8 or 149.73 – 50, Answer: PAO2 = 99.73 mm Hg (~100)

**2.** Formula: A-a gradient = PAO2 PaO2 Solution: A-a gradient = 100 – 90

Answer: A-a gradient = 10 mm Hg

**3.** Formula: PAo2 = (PB – PH2O) FiO2 – PaCO2; (FiO2 is ≥0.6)

Solution: PAO2 = 713 × 0.6 – 40 or 428 – 40 = 377.8 mm Hg

Answer: ~388 mm Hg

**4.** Formula: A-a gradient = PAO2 – PaO2

Solution: A-a gradient = 388 – 90

Answer: A-a gradient = 298 mm Hg

**5.** Patient A is perfusing well because he has a PAO2 of 99.7

PO2 of 90

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