Is It Possible to Define a Clinically Useful Safe Period of DHCA?
This requires having the ability to prospectively determine, in an individual patient, the duration of DHCA that results in morbidity equal to or less than that of the alternative perfusion strategy with continuous CPB. This is a daunting task, and it is easy to argue that we are not even close. Several factors contribute to this: lack of data, difficulty with outcome measures, and biologic variability. Despite some commendable efforts, the data gap is wide. Two clinical studies from outstanding groups have attempted to characterize the relationship between the duration of DHCA and CNS morbidity. Both studies are convincing in demonstrating the general relationship between CNS damage and increasing duration of DHCA. However, these studies, the best we have in our literature, simply underscore the limitations that exist in trying to go beyond this general relationship. In the study by Gaynor and colleagues 2 in this issue of the Journal, continuous electroencephalographic monitoring is
