Neuraxial blockade and hematoma in cardiac surgery: estimating the risk of a rare adverse event that has not (yet) occurred.

injury when large doses of heparin are used. There are, however, many potential advantages of epidural and spinal anesthesia and analgesia in cardiac surgery. There is evidence to support improved hemodynamic stability,1–4 intense analgesia,4–8 early tracheal extubation,5,6,9 improved pulmonary function,5,6 enhanced coronary perfusion,9–12 decreased ischemia, improved ventricular function, and improved metabolic profile.1,3 Other advantages may include better pulmonary toilet, early ambulation, shorter ICU stay, and cost reduction. Sympathetic blockade may be particularly useful in minimally invasive cardiac surgery, although the possibility of unscheduled CPB remains a concern. There are those who strongly oppose the use of neuraxial block in these patients because the effects of the combination of neuraxial blockade and highdose heparin have not been adequately studied, and because the possible consequence of paraplegia from spinal hematoma is too severe to justify any potential gain. In contrast, it could be argued that the risk of clinically significant hematoma following CPB is very low when proper precautions are taken, and that cardiac surgery patients should not be denied the benefits of regional blockade. There is limited experience so far to support the latter claim.1–9,14,15 A large number of cardiac surgical procedures are performed every year. Attempts to quantify the potential gain and risks associated with neuraxial blockade therefore have important implications for patients, medical care providers, and planners. The objective of this paper is to use available literature to estimate the risk of clinically significant spinal hematoma after neuraxial blockade in conventional cardiac surgery.