Cardiac surgery and intrathecal/epidural techniques: at the crossroads?

TILIZATION of intrathecal and epidural anesthesia and analgesia techniques in patients undergoing cardiac surgery has increased. 1,2 Potential benefits include improved postoperative analgesia, attenuation of the stress response to surgery, and induction of thoracic cardiac sympathectomy. These potential clinical benefits may reduce perioperative morbidity and mortality. However, substantial controversy persists regarding the risk:benefit ratio of intrathecal and epidural instrumentation in cardiac surgical patients who subsequently receive perioperative anticoagulation. In this issue of the Journal, Jacobsohn and associates 3 present the findings of their small (n = 43), prospective, randomized, blinded, placebo-controlled clinical study investigating the potential clinical benefits of intrathecal morphine in healthy patients undergoing elective cardiac surgery with cardiopulmonary bypass. The intrathecal injection (morphine or placebo) was administered immediately prior to induction of general anesthesia and perioperative care was appropriately standardized. Extubation times were equivalent between the two groups (approximately 40 min). Patients receiving intrathecal morphine exhibited enhanced postoperative analgesia, as evidenced by decreased morphine requirements and decreased visual analogue pain scores. Both groups exhibited substantial pulmonary dysfunction (per spirometry) during the immediate postoperative period yet dysfunction was less pronounced in the patients receiving intrathecal morphine. Postoperative arterial blood gases and atelectasis scores were equivalent between the two groups, as were analgesic satisfaction, hospital satisfaction, and mean hospital length of stay. Thus, intrathecal morphine provided only enhanced postoperative analgesia (yet no enhancement of analgesic satisfaction). Such findings are not new (similar results have been previously published) yet present an opportunity to critically reassess the current use of intrathecal and epidural techniques in patients undergoing cardiac surgery. Use of intrathecal and epidural techniques in patients undergoing cardiac surgery certainly enhances postoperative analgesia, may attenuate the stress response to surgery, and may induce thoracic cardiac sympathectomy. Because of enhanced flexibility (and more potential clinical benefits), most recent clinical investigations have focused on the use of thoracic epidural techniques. Intrathecal morphine was initially used in patients undergoing cardiac surgery in 1980. Since then, numerous clinical investigations (some prospective, randomized, blinded, placebo-controlled) attest to this technique’s ability to induce reliable postoperative analgesia. However, neither intrathecal opioids or local anesthetics reliably attenuate the stress response associated with cardiac surgery or reliably induce perioperative thoracic cardiac sympathectomy. In contrast to intrathecal techniques, the presence of a catheter in the epidural space allows an almost infinite number of possibilities regarding potential drugs and dosing schedules to obtain specific goals. The initial description of thoracic epidural anesthesia and analgesia applied to a cardiac surgical patient occurred in 1954. Numerous clinical investigations (none well-controlled) attest to the ability of thoracic epidural opioids and local anesthetics to reliably induce postoperative analgesia in patients after cardiac surgery. Administration of thoracic epidural local anesthetics (not opioids) has the potential to attenuate the stress response associated with the perioperative period and