CLINICAL-EXPERIENCE WITH EPIDURAL COOLING FOR SPINAL-CORD PROTECTION DURING THORACIC AND THORACOABDOMINAL ANEURYSM REPAIR

Purpose: This report summarizes our experience with epidural cooling ( EC) to achieve regional spinal cord hypothermia and thereby decrease t he risk of spinal cord ischemic injury during the course of descending thoracic aneurysm (TA) and thoracoabdominal aneurysm (TAA) repair. Me thods: During the interval July 1993 to Dec. 1995, 70 patients underwe nt TA (n = 9, 13%) or TAA (n = 61) (type I, 24 [34%], type II, 11 [15% ], type III, 26 [37%]) repair using the EC technique. The latter was a ccomplished by continuous infusion of normal saline (4 degrees C) into a T-11-12 epidural catheter; an intrathecal catheter was placed at th e L(3-4) level for monitoring of cerebrospinal fluid temperature (CSFT ) and pressure (CSFT). All operations (one exception, atriofemoral byp ass) were performed with the clamp-and-sew technique, and 50% of patie nts had preservation of intercostal vessels at proximal or distal anas tomoses (30%) or by separate inclusion button (20%). Neurologic outcom e was compared with a published predictive model for the incidence of neurologic deficits after TAA repair and with a matched (Type IV exclu ded) consecutive, control group (n = 55) who underwent TAA repair in t he period 1990 to 1993 before use of EC. Results: EC was successful in all patients, with a 1442 +/- 718 ml mean (range, 200 to 3500 ml) vol ume of infusate; CSFT was reduced to a mean of 24 degrees +/- 3 degree s C during aortic cross-clamping with maintenance of core temperature of 34 degrees +/- 0.8+/- C. Mean CSFP increased from baseline values o f 13 +/- 8 mm Hg to 31 +/- 6 mm Hg during cross-clamp. Seven patients (10%) died within 60 days of surgery, but all survived long enough for evaluation of neurologic deficits. The EC group and control group wer e well-matched with respect to mean age, incidence of acute presentati ons/aortic dissection/aneurysm rupture, TAA type distribution, and aor tic cross-clamp times. Two lower extremity neurologic deficits (2.9%) were observed in the EC patients and 13 (23%) in the control group (p < 0.0001). Observed and predicted deficits in the EC patients were 2.9 % and 20.0% (p = 0.001), and for the control group 23% and 17.8% (p = 0.48). In considering EC and control patients (n = 115), variables ass ociated with postoperative neurologic deficit were prolonged (>60 min) visceral aortic cross-clamp time (relative risk, 4.4; 95% CI, 1.2 to 16.5; p = 0.02) and lack of epidural cooling (relative risk, 9.8; 95% CI, 2 to 48; p = 0.005). Conclusions: EC is a safe and effective techn ique to increase the ischemic tolerance of tile spinal cord during TA or TAA repair. When used in conjunction with a clamp-and-sew technique and a strategy of selective intercostal reanastomosis, EC has signifi cantly reduced the incidence of neurologic deficits after TAA repair.