BRONCHOALVEOLAR LAVAGE CAUSES DECREASE IN PAO2, INCREASE IN (A-A) GRADIENT VALUE AND BRONCHOCONSTRICTION IN ASTHMATICS

The aims of this study were to (1) record the changes of (arterial oxy gen partial pressure) PaO2, (arterial carbon dioxide partial pressure) PaCO2, (percentage saturation of haemoglobin with oxygen in arterial blood) SaO(2) and alveolar-arterial (A-a) oxygen gradiant resulting fr om bronchoalveolar lavage (BAL) in asthmatic and normal subjects; (2) measure changes in forced expiratory volume in 1s (FEV1), vital capaci ty forced (FVC) associated with BAL; and (3) assess possible predictiv e factors for the degree of hypoxaemia and impairment of spirometry re sulting from BAL. Bronchoscopy and BAL (150 ml) were performed in 24 a sthmatics and 15 healthy subjects. Serial arterial blood samples (radi al artery) were obtained in all subjects: T-1 and before T-2 after loc al anaesthesia; T-3 at end of bronchoscopy; T-4 after BAL and 5 min, 1 5 min, 1 h, 2 h, 8 h and 24 h (T-5-T-10) after the procedure, FEV1 and FVC were measured immediately before and 5 min after bronchoscopy. Ba seline PaO2 was lower in asthmatics (10.2 +/- 0.8 kPa) than in healthy subjects (10.8 +/- 0.8). Both groups showed a significant decease in PaO2, and a significant widening in (A-a) oxygen tension gradiant at T 3-9, with respect to T-1 (P<0.05). PaO2 reached a significantly lower value in asthmatics (7.1 +/- 0.6 kPa) than in HS (7.7 +/- 0.5; P<0.05) . In asthmatics, FEV1, FVC and the ratio FEV1/FVC decreased significan tly after BAL (P<0.001). In healthy subjects, FEV1 and FVC decreased s ignificantly (P<0.001), whereas FEV1/FVC did not. The fall in FEV1 aft er BAL was significantly greater in asthmatics (32.4 +/- 10.0%) than i n healthy subjects (17.7 +/- 4.6; P<0.001). Severity of asthma, baslin e FEV1 or initial PaO2 did not predict the degree of hypoxaemia or the fall of FEV1. It is concluded that BAL causes mon severe hypoxaemia a nd a greater decrease in FEV1 in asthmatics compared to healthy subjec ts, strongly supporting the recommendation of special caution and care ful monitoring when BAL is undertaken in asthmatics.