Lateral position test and quantitative lung scan in the preoperative evaluation for lung resection

The postpneumonectomy FEV1 was predicted in 24 patients with severe chronic obstructive pulmonary disease (FEV1 less than or equal to 2.0 L) and a lung mass using the quantitative lung scan (QLS) and lateral position test (LPT). Although a good correlation (r = .72, p = 0.0006) was found between the FEV1 predicted by QLS and LPT, there was more than 10 percent difference between the result in 59 percent of the subjects. A subgroup of these patients performed multiple (two to five) LPTs, and the results were calculated blindly to assess variability. The variation seen was 14 times greater than in previously reported normal subjects. Calculations suggest that as many as 37 tracings would be needed on each patient to obtain an acceptably low measurement error. Whereas there was a good overall correlation between the predicted postpneumonectomy FEV1 using both methods, the variability found with LPT would suggest extreme caution in its use.