- Paper Report
- Open Access
Atropine test is a useful adjunct to the diagnosis of brain stem death
- Arpan Guha1
© Current Science Ltd 2000
- Published: 6 March 2000
- Atropine test
- brain stem death
It is widely accepted that the absence of cranial nerve reflexes and apnea is synonymous with death, although there may be a cardiac output. Strict criteria for brain stem death tests are in place in most countries, and involve the initial exclusion of any confounding factors such as residual sedation, metabolic derangements and hypothermia. However, laboratory investigations may not form part of the test protocol in many countries. The 'atropine test' was first proposed in 1975 as an adjunct to brain stem tests, and relies on the fact that there is only a contribution from the sympathetic nervous system to the heart rate in brain dead patients. The test is considered positive if the administration of 2-3 mg of atropine fails to increase the heart rate by 3%. This was considered to be helpful in deciding the appropriate timing for further tests, thus avoiding unnecessary investigations when these were demanded by the test protocol.
. Prospective, observational study.
. 45 patients with intracranial hypertension due to primary supratentorial lesions in whom brain death was clinically suspected.
. TCD studies of the cerebral circulation carried out simultaneously to correlate the findings of the 'atropine test'.
. Atropine was injected in a graded manner up to a maximum dose of 3 mg, with the test aborted (positive test) if a tachycardic response from baseline was observed.
. Other treatment modalities and support remained unchanged during this period.
Negative result on first atropine test: 32/45 patients
Positive result on first atropine test: 13/45 patients
TCD in the positive test group: (n = 13) Supratentorial circulatory arrest: 8/13 patients
Flow present but evidence of massive rise in ICP:5/13 patients
Atropine test became negative over 4-12 h in the latter group of patients. Comparison of results of the atropine test with TCD showed a sensitivity of 100% and specificity of 98.6%.
Testing the functional integrity of the brain stem is a widely accepted method of diagnosing death. In most parts of the world, testing is carried out separately by two senior doctors with an interim period between the two tests. The physicians must ensure that there is no residual effect of sedative and muscle relaxant drugs that might have been administered during the course of the patient's stay in hospital.
Metabolic derangements and hypothermia must be absent. Many countries require confirmatory investigations such as EEG and transcranial Doppler in addition to clinical tests.