Sensitivity and Specificity of Atropine Injection for Testing for Irreversible Loss of Brain Function: Experiences From 394 Examinations

Abstract

Objectives

Testing for brain death/death by neurologic criteria includes proof of irreversible loss of all brain functions. Intravenously administered atropine can serve as a complementary clinical test. This study determines the cut-off value, sensitivity, and specificity of the atropine test and examines implications for the safety of existing scientific guidelines.

Methods

A prospective multicenter observational study included patients who received atropine (2 mg intravenously) as part of an investigation for brain death/death by neurologic criteria. Data from brain death/death by neurologic criteria protocols, vital signs records, and diagnostic reports were collected in order to calculate the sensitivity and specificity of the atropine test per se and in comparison to the standard tests.

Results

The study included 394 examinations in 257 patients (51.6 years, SD 16.3 years, 123 men, and 134 women) with suspected brain death/death by neurologic criteria.

In brain-dead patients, there was no increase in heart rate above 10 bpm (i.e., specificity of 100% of a positive atropine test > 10 bpm). Although of low sensitivity (17%) in proving residual brain function, the atropine test is twice as sensitive in revealing remaining brain functions as mandatory clinical tests (corneal, cough, and pupillary reflex p < 0.05, apnea test and unresponsiveness to pain p < 0.10).

Conclusion

A cut-off value of 10 bpm achieves very good specificity, but only low sensitivity. However, the sensitivity of the atropine test was more than twice as high as that of all mandatory tests. Therefore, we suggest considering the simple atropine test in brain death/death by neurologic criteria diagnostics at least where brain perfusion investigations are not used.