Sun14November1246PM 5
A 35-year-old male is admitted to the critical care unit following an overdose of heroin. He is intubated and is receiving ventilatory support.
Which one of the following total static compliance (lung and chest wall) measurements would you expect in this patient?
(Please select 1 option)
20 ml/cmH2O
100 ml/cmH2O Correct
200 ml/cmH2O
10 ml/cmH2O
1 ml/cmH2O
Explanation
Static lung compliance is the change in volume for any given change in pressure.
Static compliance is measured at a period when there is no gas flow, for example during an inspiratory or expiratory pause.
Compliance =
The units are ml/cmH2O or L/cmH2O
Intrapleural pressure can be measured indirectly using an oesophageal manometer.
Respiratory volumes can be measured at the mouth using a pneumotachograph.
The normal compliance (Cl) of a normal lung is 200 ml/cmH2O.
Total static compliance (Ct) includes the compliance of the chest wall (Ccw) that is also 200 ml/cmH2O.
Summation of elastance = 1/compliance.
Ct = Cl + Ccw
1/Ct = 1/200 + 1/200 =
1/Ct = 0.005 + 0.005 = 0.01
1/Ct = 0.01 by rearranging equation Ct = 1/0.01 = 100ml/cmH2O.
Answer Statistics
1
21%
2
49%
3
26%
4
4%
5
2%
Times answered: 228