atropine test

 Q: What is the physiological basis of using atropine in establishing brain death?

Answer: The dorsal motor vagal nucleus is in the medulla. Atropine works via this center and provides an assessment of caudal medullary function. This is one of the last functions which gets lost in brain death. Atropine provides a restricted assessment of brainstem function. 

The test is performed by giving 2-3 mg atropine intravenously. The test is considered positive (means brain is dead) if heart rate fails to increase by 3% compared with basal heart rate.

This excludes people with denervation like a previous heart transplant.

#neurology

References:

1. Hüttemann E, Schelenz C, Sakka SG, Reinhart K. Atropine test and circulatory arrest in the fossa posterior assessed by transcranial Doppler. Intensive Care Med. 2000 Apr;26(4):422-5. doi: 10.1007/s001340051176. PMID: 10872134. 

2. Machado C. Diagnosis of brain death. Neurol Int. 2010;2(1):e2. Published 2010 Jun 21. doi:10.4081/ni.2010.e2