Abstract
The influence of drugs must be excluded before making a diagnosis of brain death. No standard guidelines currently exist for evaluating drug influence, however. We studied 29 drugs influencing brain death diagnosis. The therapeutic range is known in 41% of these drugs. They have potential metabolites in 55%. The duration of efficacy is known in 72%. We term the time during which plasma concentration decreases to one tenth “decilife.” To estimate drug influence elimination time, we propose 3 calculation times: H-time (sum of efficacy duration and elimination half-life), D-time (sum of efficacy duration and decilife), and F-time (4 times the elimination half-life). Plasma drug concentration was measured in 10 cases. We then compared efficacy duration, half-life, and the 3 calculated times. H-time is the most adequate among the 3 calculated times if both efficacy duration and half-life are known. F-time is useful if only the half-life is known. If drug substances have potential metabolites, elimination time should be estimated longer. If neuromuscular blocking agents have been administered, examination with a bedside peripheral nerve stimulator is required. Adequate recovery of neuromuscular function requires the return of the train-of-4 ratio to more than 0.90. We have thus proposed practical guidelines to exclude drug influence before brain death is diagnosed.
