1. Comparison of total lung capacity (TLC) measured by single-breath (SB) gas dilution, rebreathing (RB) gas dilution, and plethysmography (pleth) as the reference in normal subjects and patients with emphysema.
Comparison of total lung capacity (TLC) measured by single-breath (SB) gas dilution, rebreathing (RB) gas dilution, and plethysmography (pleth) as the reference in normal subjects and patients with emphysema. Bars represent quartiles of FEV1 % predicted as an index of obstruction: quartile 1 = lowest quartile for FEV1 %. P values represent the interaction between FEV1 % (as a continuous measure) and the respective lung volume. P values < .05 indicate that lung volume agreement varies with the degree of obstruction (FEV1 %). TLCSB significantly underestimates lung volume when compared to either RB or pleth. TLCRB does not show significant interaction with FEV1 % in the patients with emphysema, suggesting that the rebreathing technique is minimally affected by airway obstruction. (From Reference 48, with permission.)‏
Gregg L Ruppel Respir Care 2012;57:26-38
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