RT Journal Article
SR Electronic
T1 Pulmonary gas exchange response following allergen challenge in patients with allergic asthma
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 1176
OP 1183
DO 10.1183/09031936.93.05101176
VO 5
IS 10
A1 L Lagerstrand
A1 K Larsson
A1 E Ihre
A1 O Zetterstrom
A1 G Hedenstierna
YR 1992
UL http://erj.ersjournals.com/content/5/10/1176.abstract
AB Pulmonary gas exchange was studied in 8 patients with allergic asthma before and after allergen challenge. Ventilation-perfusion relationships were assessed by the multiple inert gas elimination technique and forced expiratory flow by conventional spirometry. Measurements were made before, 7-8 minutes, and 0.5, 2.5 and 5 hours after challenge. During baseline conditions all patients showed normal forced expiratory flow (FEV1 3.9 +/- 0.77 (SD) l) and gas exchange expressed as the dispersion of pulmonary blood flow, log SDQ (0.35 +/- 0.08), (one of the common descriptors of ventilation-perfusion (VA/Q) inequality). Immediately after challenge there were significant decreases in FEV1 (to 2.3 +/- 0.75 l) and arterial PO2 (from 13.1 +/- 0.9 to 9.5 +/- 1.2 kPa). The developed ventilation-perfusion inequalities were similar to those found in other asthma studies, i.e. mainly a broad (log SDQ increased to 0.73 +/- 0.30) and sometimes bimodal distribution of the perfusion. Thirty minutes after challenge FEV1 significantly improved to 3.2 +/- 1.18 l while log SDQ remained high (0.71 +/- 0.32). Two and a half hours after challenge log SDQ was reduced and almost normalized to 0.38 +/- 0.07. Five patients developed a late phase reaction with decreasing flow rates after 5 hours. Three of these patients also showed increased log SDQ. There was no clear relationship between gas exchange mismatch and reduced forced expiratory flow. The results support the hypothesis that reduced expiratory flow and gas exchange impairment are caused by different pathophysiological mechanisms.