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.

MATERIAL 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 infratentorial 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.