Background: Adenosine-induced asystole has been used to induce transient systemic hypotension for various vascular procedures. Dose-response characteristics of adenosine-induced ventricular asystole have not been determined.
Methods: During endovascular embolization of cerebral arteriovenous malformations, the authors performed a series of adenosine test injections to establish a dose-response relation in each patient. After an interval of 3-10 min, the dose was escalated by 10-20 mg for each injection to achieve an end point of 20-30 s of stable mean arterial pressure (MAP) reduction to 25-30 mmHg. All patients received constant infusion of nitroprusside (approximately 1 microgram. kg-1. min-1) throughout the procedure.
Results: The authors studied four adult patients (age, 22-44 yr; two patients had two separate procedures) and one pediatric patient (age, 4 yr). Twenty-three adenosine injections resulted in measurable asystole. The adenosine dose was 0. 98 +/- 0.40 mg/kg (mean +/- SD), and the dose range was 0.24-1.76 mg/kg (6-90 mg). The duration of asystole, MAP < 30 mmHg, and MAP < 50 mmHg, were 8 +/- 3 s, 18 +/- 12 s, and 50 +/- 29 s, respectively. The minimum MAP and the MAP for the first 20 s were 16 +/- 3 mmHg and 30 +/- 9 mmHg, respectively. There was a linear relation between adenosine dose and the duration of hypotension with MAP < 30 mmHg and MAP < 50 mmHg.
Conclusions: In the dose range studied, a series of adenosine test injections can be used to determine optimal adenosine dose for induction of transient profound hypotension.