The purpose of this study was to assess whether during standard methacholine (Mch) challenge (concentration up to 128 mg·mL-1) healthy supine subjects a) develop tidal expiratory flow limitation (FL) and hyperinflation, and b) whether the onset of tidal FL is associated with dyspnoea. Eight healthy subjects were studied. Dyspnoea was assessed using the Borg scale, FL by the negative expiratory pressure (NEP) method and hyperinflation in terms of decrease in inspiratory capacity (IC). Seven patients became flow limited at Mch doses ranging 4-64 mg·mL-1, with FL encompassing 34-84% of the control tidal volume. In six of them the onset of tidal FL was associated with little or no dyspnoea and a modest degree of hyperinflation (ΔIC <-0.4 L). In one subject, however, onset of FL was associated with a substantial reduction in IC (0.58 L) and moderately severe dyspnoea. In all of these seven subjects FL was transiently reversed after an IC manoeuvre. In conclusion, the results show that a) mo...
Flow limitation and dyspnea in normal supine subjects during methacholine challenge
VOLTA, Carlo Alberto;
1999
Abstract
The purpose of this study was to assess whether during standard methacholine (Mch) challenge (concentration up to 128 mg·mL-1) healthy supine subjects a) develop tidal expiratory flow limitation (FL) and hyperinflation, and b) whether the onset of tidal FL is associated with dyspnoea. Eight healthy subjects were studied. Dyspnoea was assessed using the Borg scale, FL by the negative expiratory pressure (NEP) method and hyperinflation in terms of decrease in inspiratory capacity (IC). Seven patients became flow limited at Mch doses ranging 4-64 mg·mL-1, with FL encompassing 34-84% of the control tidal volume. In six of them the onset of tidal FL was associated with little or no dyspnoea and a modest degree of hyperinflation (ΔIC <-0.4 L). In one subject, however, onset of FL was associated with a substantial reduction in IC (0.58 L) and moderately severe dyspnoea. In all of these seven subjects FL was transiently reversed after an IC manoeuvre. In conclusion, the results show that a) mo...I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
