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 atropine) correctly predicts circulatory arrest in the fossa posterior during craniocaudal 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 atropine test (AT) and a transcranial Doppler sonography were performed simultaneously and, if necessary, repeatedly. Measurements and results: Forty-four patients fulfilled the typical criteria of a supratentorial and infra- tentorial circulatory arrest as the atropine test became negative. In one patient, who had undergone a decompressive craniectomy for uncontrollable intracranial pressure 4 h prior to the AT testing, we found a negative AT in the presence of an antegrade supratentorial and infratentorial flow. Conclusion: A negative atropine test indicates a circulatory arrest in the fossa posterior in patients with primary supratentorial lesions and craniocaudal herniation. In patients with brain-stem lesions, however, a negative atropine test does not unequivocally indicate a circulatory arrest.