Atropine test and circulatory arrest in the fossa posterior assessed by transcranial Doppler

Objective: To evaluate whether a negative atropine test (i.e., increase in heart rate of less than 3 % after intravenous administration of 3 mg atropi ne) correctly predicts circulatory arrest in the fossa posterior during cra niocaudal herniation in patients with primary supratentorial lesions. Materials and methods: Prospective, observational clinical study. Setting: Two surgical intensive care units in a university hospital. Patients: In 45 consecutive patients with suspected brain death, an atropin e test (AT) and a transcranial Doppler sonography were performed simultaneo usly and, if necessary, repeatedly. Measurements and results: Forty-four patients fulfilled the typical criteri a of a supratentorial and infra- tentorial circulatory arrest as the atropi ne test became negative. In one patient, who had undergone a decompressive craniectomy for uncontrollable intracranial pressure 4 h prior to the AT te sting, we found a negative AT in the presence of an antegrade supratentoria l and infratentorial flow. Conclusion: A negative atropine test indicates a circulatory arrest in the fossa posterior in patients with primary supratentorial lesions and cranioc audal herniation. In patients with brain-stem lesions, however, a negative atropine test does not unequivocally indicate a circulatory arrest.