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NBME 22 Answers

nbme22/Block 4/Question#4

A 24-year-old man who is comatose is admitted to ...

25 mL/cm H2O

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His tidal volume was 500 mL. End-expiratory was +5 cm and end-inspiratory was +25. We were supposed to use the difference in airway pressure, and not the end-inspiratory pleural pressure (+20).

Compliance = ΔV/ΔP = 500 / 20 = 25 mL/cm H2O

some-zheimers  Great explanation. In general, also a great idea to pay attention to the units. I studied Physics in undergrad and have got one or two questions based purely on following the units, when the formula slips. +3  
endochondral1  is that equation in FA? +  
redvelvet  yes @endochondral1, at page 651 in 2019FA +  




How do you know that respiratory system compliance is 25 ml/cm h2o?

alwaysanonymous  His tidal volume was 500 mL. End-expiratory was +5 cm and end-inspiratory was +25. We were supposed to use the difference in airway pressure, and not the end-inspiratory pleural pressure (+20). Compliance = ΔV/ΔP = 500 / 20 = 25 mL/cm H2O +2