[Plethysmographic and radiologic measurement of the total lung capacity during acute attack of bronchial asthma].

There is controversy on the behavior of total lung capacity (TLC) during an acute asthma attack because the severe airflow obstruction causes an overestimation of the intrathoracic gas measured by plethysmography. We measured plethysmographic and radiologic TLC (TLCpl, TLCrx) in 17 patients with acute asthma, at admission and 3-5 days later when clinical and spirometric improvement was seen. TLCrx was measured planimetrically from routine chest X-rays in postero-anterior and lateral projection. Patients had a mean age of 32 +/- 15 years (ranging from 8-53) and six were males. FEV1 and FVC increased significantly in the second evaluation (1.36 +/- 0.7 vs 1.99 +/- 0.7 L, and 1.97 +/- 0.9 vs 2.6 +/- 1 L respectively, p less than 0.05), whereas airway resistance decreased (13.4 +/- 5.3 vs 9.8 +/- 3.4 cm H2O/L/s, p less than 0.05). On the other hand, we did not find a significant change in TLCpl (4.4 +/- 1.1 vs 4.6 +/- 1.2 L) nor in TLCrx (4.2 +/- 0.9 vs 4.1 +/- 0.8 L). We found no significant difference between TLCpl and TLCrx.