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Effects of Perioperative Central Neuraxial Analgesia on Outcome After Coronary Artery Bypass Surgery: A Meta Analysis.Liu SS, Block BM, Wu CL. Anesthesiology 2004; 101: 153-161.An Epidural Hematoma in an Adolescent Patient After Cardiac Surgery (Case Report).Rosen DA, Hawkinberry DW, Rosen KR, et al. Anesth Analg 2004; 98:966-969.Reviewer: Mark A. Chaney, MD
Use of regional anesthetic techniques in patients undergoing cardiac surgery, while seemingly increasing in popularity, remains extremely controversial, prompting numerous Editorials by recognized experts in the field of cardiac anesthesia.1-4 All cardiac anesthesiologists should be aware of two recent publications that may help one assess the risk:benefit ratio when contemplating utilizing regional anesthetic techniques in patients undergoing cardiac surgery. In the first, a meta-analysis by Liu and associates published in Anesthesiology assessed effects of perioperative central neuraxial analgesia on outcome after coronary artery bypass surgery. These authors, via MEDLINE and other databases, searched for randomized controlled trials in patients undergoing coronary artery bypass surgery with cardiopulmonary bypass. Fifteen trials enrolling 1,178 patients were included for thoracic epidural anesthesia analysis and seventeen trials enrolling 668 patients were included for intrathecal analysis. Thoracic epidural techniques did not affect incidences of mortality or myocardial infarction yet reduced risk of dysrhythmias (atrial fibrillation and tachycardia), reduced risk of pulmonary complications (pneumonia and atelectasis), reduced time to tracheal extubation, and reduced analog pain scores. Intrathecal techniques did not affect incidences of mortality, myocardial infarction, dysrhythmias, or time to tracheal extubation and only modestly decreased systemic morphine utilization and pain scores (while increasing incidence of pruritus). These authors conclude that central neuraxial analgesia does not affect rates of mortality or myocardial infarction following coronary artery bypass grafting yet is associated with improvements in faster time until tracheal extubation, decreased pulmonary complications and cardiac dysrhythmias, and reduced pain scores. However, the authors also note the majority of potential clinical benefits offered by central neuraxial analgesia (earlier extubation, decreased dysrhythmias, enhanced analgesia) may be reduced and/or eliminated with changing cardiac anesthesia practice using fast-track techniques, use of beta adrenergic blockers or amiodarone, and/or use of NSAIDs or COX-2 inhibitors. These authors also note that the risk of spinal hematoma due to central neuraxial analgesia in patients undergoing full anticoagulation for cardiopulmonary bypass remains uncertain. In the second, the first ever case report of an epidural hematoma associated with a thoracic epidural catheter inserted in a patient prior to cardiac surgery was published in Anesthesia and Analgesia. This 18-year-old male had a thoracic (T9-10) epidural catheter uneventfully inserted following induction of general anesthesia (patient had intense fear of needles) immediately prior to initiation of cardiopulmonary bypass for aortic valve replacement surgery. Three hours elapsed from instrumentation to systemic heparinization. The entire intraoperative course and immediate postoperative course were uneventful (tracheally extubated soon after surgery, ambulating without difficulty on the first postoperative day). Forty-nine hours following surgery, intravenous heparin therapy was initiated (prosthetic valve thrombopro-phylaxis). Fifty-three hours following surgery, alteplase (thrombolytic drug) was used to flush a dysfunctional intravenous catheter. Within two hours of intravenous alteplase administration, the patient reported intense back pain while ambulating. At this point, the epidural catheter was removed. The activated partial thromboplastin time assessed at this time (during catheter removal) was 87.4 seconds (normal range 24.8 - 37.3 seconds). The patient was also thrombocytopenic at this time. Upon catheter removal, the patient experienced sudden onset of numbness and weakness distal to T9. Intravenous heparin was discontinued, a computed tomographic scan was inconclusive, requiring a magnetic resonance imaging scan, which revealed an epidural hematoma. Five hours from the onset of neurologic symptoms, the patient underwent surgical evacuation of the hematoma (which extended from the T8 to T11 levels). Intraoperatively, intravenous methylprednisolone (30 mg/kg) was administered, followed by an infusion (5.4 mg/kg/hr) which was continued for 72 hours. Twenty-four hours postlaminectomy, the patient demonstrated mild residual lower extremity motor and sensory deficits. Six weeks later, his neurological examination had returned to normal. The authors note the factors affecting coagulation in this patient (heparin, alteplase, thrombocytopenia) that likely led to hematoma formation and theorize that removing the catheter may have increased bleeding, further compounding the problem. Use of regional anesthetic techniques in patients undergoing cardiac surgery remains extremely controversial. One of the main reasons such controversy exists (and likely will continue for some time) is that the numerous clinical investigations regarding this topic are suboptionally designed and utilize a wide array of disparate techniques preventing clinically useful conclusions all can agree on.1-6 The recent publications by Liu and associates (meta analysis regarding clinical outcome) and Rosen and associates (first case report of epidural hematoma), while not able to definitively settle all issues, help to shed additional light on this controversial topic. References:
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