After appropriate pre-treatment, 32 dogs were given an injection of epinephrine, lmg, iv, to test completeness of adrenergic blockade. Approximately 15 minutes following the test injection when blood pressure and pulse had returned to pre-injection levels, the animals were subjected to obstructive asphyxia by clamping the endotracheal tube at end expiration. When aortic pulse pressure had decreased to zero, the animals were allowed to remain arrested for five minutes after which mechanical ventilation and external cardiac massage were instituted. After 30 seconds of resuscitation, epinephrine, 1 mg, was administered intravenously and resuscitation performed for five minutes or until resumption of spontaneous circulation. According to the type of pretreatment given, the dogs were divided into four groups of eight dogs each. Group A (alpha blocked) received phenoxybenzamine, 70 mg/kg, infused over one hour, which abolished the diastolic response to the test epinephrine injection and depressed the systolic response to less than 20 torr. Group B (beta blocked) received propranolol, 5 mg/kg, infused over 10 minutes which prevented any increase in heart rate following the test injection. Group C (alpha and beta blocked) received both phenoxybenzamine, 70 mg/kg; and propranolol, 5 mg/kg. Group D (control) was not pre-treated. In all dogs successfully resuscitated, rechallenge with epinephrine was performed to establish continuity of adrenergic blockade. Group results were compared in terms of restoration of spontaneous circulation lasting at least one minute. No dogs in Groups A or C were resuscitated. Six out of eight dogs in Group B and seven out of eight dogs in Group D were successfully resuscitated; an incidence of resuscitation significantly different from either Group A or C (p<0.01). There were no differences in the resuscitated dogs in the time for resuscitation or the heart rate, systolic pressure, or diastolic pressure at the time of resuscitation.
|Original language||English (US)|
|Issue number||3 SUPPL|
|State||Published - Jan 1 1979|
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine