ABSTRACT
The severe impairment of cardiovascular function that takes place during an asthmatic attack may in itself be fatal or, if not, the patient may be tipped into death by drugs that have a well-defined and pronounced cardiovascular effect. The reversal of the normal cardiovascular responses to three beta adrenoceptor agonists (isoprenaline, salbutamol, and orciprenaline) has been demonstrated. Newer beta agonists (terbutaline, fenoterol, and salmeterol) have been introduced for the treatment of asthma. The cardiovascular collapse produced by these drugs during hypoxemia was attributed to an effect on beta adrenoceptor because it occurred with isoprenaline, orciprenaline, and salbutamol and was prevented by propranolol. Propranolol was administered in doses that blocked the effects of isoprenaline on heart rate and blood pressure during respiration with room air. Following pretreatment with propranolol, the repeated injection of isoprenaline during respiration with 12% oxygen/88% nitrogen did not produce the abnormal response leading to cardiac asystole and death.
