A helium dilution test has just been performed on a patient. The following results are obtained:
FRC 5.0 L
VC 4.0 L
ERV 1.5 L
TLC was calculated to be 6.0 L by plethysmography. From this information, a pulmonary function technologist should conclude that the patient
- Had inadequate intrapulmonary mixing of inspired gas, resulting in an erroneous FRC.
- Did not perform the slow vital capacity properly, resulting in too low an FRC by helium dilution.
- Was turned into the helium dilution circuit at a lung volume considerably above FR
- Did not remain in the helium dilution breathing circuit long enough for equilibration.
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