The aims of this study were to (1) record the changes of (arterial oxygen partial
pressure) PaO2, (arterial carbon dioxide partial pressure) PaCO2, (percentage saturation
of haemoglobin with oxygen in arterial blood) SaO2 and alveolar-arterial (A-a) oxygen
gradiant resulting from bronchoalveolar lavage (BAL) in asthmatic and normal subjects;
(2) measure changes in forced expiratory volume in 1 s (FEV1), vital capacity forced
(FVC) associated with BAL; and (3) assess possible predictive factors for the degree
of hypoxaemia and impairment of spirometry resulting from BAL. Bronchoscopy and BAL
(150 ml) were performed in 24 asthmatics and 15 healthy subjects. Serial arterial
blood samples (radial artery) were obtained in all subjects: T1 and before T2 after
local anaesthesia; T3 at end of bronchoscopy; T4 after BAL and 5 min, 15 min, 1 h,
2 h, 8 h and 24 h (T5-T10) after the procedure, FEV1 and FVC were measured immediately
before and 5 min afer bronchoscopy. Baseline PaO2 was lower in asthmatics (10.2 +/-
0.8 kPa) than in healthy subjects (10.8 +/- 0.8). Both groups showed a significant
decrease in PaO2, and a significant widening in (A-a) oxygen tension gradiant at T3-9,
with respect to T1 (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 significantly after BAL (P < 0.001). In healthy subjects,
FEV1 and FVC decreased significantly (P < 0.001), whereas FEV1/FVC did not. The fall
in FEV1 after BAL was significantly greater in asthmatics (32.4 +/- 10.0%) than in
healthy subjects (17.7 +/- 4.6; P < 0.001). Severity of asthma, basline FEV1 or initial
PaO2 did not predict the degree of hypoxaemia or the fall of FEV1. It is concluded
that BAL causes more severe hypoxaemia and a greater decrease in FEV1 in asthmatics
compared to healthy subjects, strongly supporting the recommendation of special caution
and careful monitoring when BAL is undertaken in asthmatics.