Clinical Trials and Research undertaken into the Buteyko Method and related issues.
Cardiovascular side effects of inhaled salbutamol in hypoxic asthmatic patients Source: Thorax; London; Jul 2001; J Burggraaf; R G J Westendorp; J C C M In't Veen; R C Schoemaker; et al;
Abstract Background-Beta-2 adrenoceptor agonists have been associated with sudden death in asthma patients but the cause and underlying mechanism are unclear. Animal experiments indicate that the combination of hypoxia and beta^sub 2^ agonists may result in detrimental cardiovascular effects. A study was undertaken to investigate the effect of hypoxia on the systemic vascular effects of salbutamol in patients with asthma who are hypoxic by assessing forearm blood flow (FBF) as a measure of peripheral vasodilatation. Methods-Eight men with mild asthma underwent the following treatments: normoxia + placebo (NP), normoxia + salbutamol (NS), hypoxia + placebo (HP), and hypoxia + salbutamol (HS). The period of mask breathing started at t=0 minutes, lasted for 60 minutes, and at 30 minutes 800 (mu)g salbutamol was inhaled. The experiment was completed 30 minutes after the inhalation (t=60 minutes). For the hypoxia treatment the SpO^sub 2^= level was 82%. Differences between treatments were sought using factorial ANOVA on percentage change from the pretreatment value. Results-There were no significant differences in blood pressure and potassium levels between the treatments. After 60 minutes the increase in FBF was 13% (95% CI -12 to 39) more for HP treatment than for NP, 21% (95% Cl -5 to 46) more for NS than for NP, and 32% (95% CI 7 to 58) more for HS than for HP (p=0.016). The inhalation of salbutamol during hypoxia resulted in a significant increase in FBF of 45% (95% CI 20 to 71) compared with NP (p=0.001). Conclusion-Patients with asthma who are hypoxic and inhale beta^sub 2^ agonists have serious systemic vascular side effects which may be an additional explanation for the association between asthma treatment and sudden death. (Thorax 2001;56:567-569) Keywords: asthma; hypoxia; beta^sub 2^ agonists