High thoracic epidural anesthesia in cardiac surgery: risk factors for arterial hypotension.

There is an interest in the use of high thoracic epidural anesthesia in cardiac surgery, because experimental and clinical studies have suggested that central neuroaxial blockade attenuates the response to surgical stress and improves myocardial metabolism and perioperative analgesia-thus enabling earlier extubation and a smoother postoperative course. Matters of major concern in the adoption of high thoracic epidural anesthesia in cardiac surgery are neurologic injury secondary to neuroaxial hematoma and hypotension secondary to sympatholysis. The risk associated with possible neuraxial hematoma caused by high thoracic epidural anesthesia has been thoroughly investigated and largely discounted, but scant attention has been devoted to the onset of hypotensive episodes in the same setting. We analyzed the hypotensive episodes that occurred in a series of 144 patients who underwent on-pump cardiac surgery procedures. Among the patient variables that we tested in a multivariate logistic-regression model, only female sex was found to be significantly correlated with hypotension. In order to decrease the incidence and severity of hypotensive episodes resulting from anesthetic blockade, anesthesiologists need to monitor, with special care, women patients who are under high thoracic epidural anesthesia. Further studies are needed in order to determine why women undergoing open heart surgery under high thoracic epidural anesthesia are at a relatively greater risk of hypotension.