Background:
Most general cases do not involve the need for cardiac arrest to achieve surgical hemostasis; therefore many anesthesiologists never use adenosine during intraoperative management. Nonetheless, it is important to be aware of its use for surgical emergencies.
Case Description:
48 year old healthy Caucasian female presented with a sudden onset headache while at dinner the night prior. On admission, CT scan demonstrated subarachnoid hemorrhage from a ruptured supraclinoid aneurysm. Vitals were stable and there were no gross neurologic deficits. She was taken to the OR urgently for craniotomy and aneurysm clipping. She was induced with propofol 150 mg over 5 minutes, fentanyl 100 mcg and rocuronium 50 mg, and intubated with a video-mac and 7.0 ETT. Arterial and central lines were placed, and surgery began uncomplicated. About 2 hours into the case, the surgeon requested burst suppression in anticipation of clipping the aneurysm, therefore propofol 100 mg was bolused. During the dissection, brisk arterial bleeding was noted to arise from the area of the aneurysm resulting in significant blood loss and an inordinate amount of brain swelling. A temporary clip was placed over the proximal right supraclinoid internal carotid artery, but bleeding continued at a rapid pace. Adenosine 6 mg rapid IV push was administered twice, 5 minutes apart. Eventually, the aneurysm was secured with a titanium clip. Due to brain edema, a decompressive craniectomy was performed and an external ventricular drain was placed. She was transported to CT and then to ICU with stable vital signs. She was discharged home on POD #26 with left upper and lower extremity without movement to noxious stimuli. Nearly 4 months later, the patient returned for an uncomplicated right cranioplasty. At this time her neurologic exam had made a great improvement with only some residual left upper extremity weakness.
Discussion:
Anesthesia goals and objectives for intracranial aneurysm surgery should include having blood available, preventing aneurysm rupture/hypertension, avoiding factors that promote cerebral ischemia/vasospasm, and proper neuromuscular relaxation.
Temporary clip application cuts off blood supply to a region of the brain and induces ischemia. This is usually well tolerated for a short amount of time, but it can be difficult to predict the duration. Therefore, many prefer the use of pharmacologic neuroprotection, such as propofol burst suppression, prior to clipping. However, when occlusion/clipping of the parent artery is difficult, or when inadvertent aneurysmal rupture occurs, the emergent administration of adenosine can be used to produce flow arrest that can facilitate clip ligation.
Adenosine, commonly dosed at 0.3-0.4 mg/kg ideal body weight, results in a decrease in atrial and ventricular electrical activity. This results in bradycardia, atrioventricular nodal blockade, and sinus pause. This subsequently produces a rapid and profound decrease in systemic and cerebral perfusion pressure for about 45 seconds, which decreases aneurysm neck turgor and facilitates clip ligation.
Adenosine has several possible side effects, namely bronchospasm, AV conduction block, coronary vascular steal, increased blood levels if co-administered with nimodipine, and allergy.
