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Accuracy and Precision of Helium Dilution Technique and Body Plethysmography in Measuring Lung Volumes

1973; Taylor & Francis; Volume: 32; Issue: 3 Linguagem: Inglês

10.3109/00365517309082471

1502-7686

Carl G. Schaanning, A Gulsvik,

Respiratory Support and Mechanisms

Lung volumes were measured concurrently by means of a closed helium dilution technique (HDT) and body plethysmography in 10 healthy subjects and in 10 patients with hyperinflation due to obstructive lung disease. Two sets of duplicate measurements were performed in each subject and with each method. The plethysmographic method yielded a higher FRC than the gas dilution method, with a mean difference of 0.3 liters in healthy subjects and 0.5 liters in obstructed patients. Interposed VC maneuvers during the gas wash-in did not influence this difference in the healthy subjects but reduced it in the obstructed patients. The standard deviation of a single FRC determination was virtually equal in both methods, about 0.15 and 0.20 liters in healthy and obstructed subjects, respectively. For practical purposes, a difference between two duplicate FRC measurements exceeding 10% can be considered significant (p=0.05). A volume determination by means of plethysmography required only one-third of the time necessary for the HDT.