Faculty Bibliography

Twenty-four patients undergoing abdominal aortic aneurysm (AAA) repair were studied to compare the effects of lumbar epidural anesthesia (LEA) and general anesthesia (GA) on plasma catecholamine levels and hemodynamics before and during infrarenal aortic cross-clamping. Patients received either a high dose of opioid anesthetic (GA group, n = 12), or lumbar epidural anesthesia to T4 sensory level with a light general anesthetic (LEA group, n = 12). Systemic vascular resistance (SVR) and norepinephrine (NE) and epinephrine (E) levels were measured before anesthetic induction (before epidural activation in the LEA group, and before general anesthesia induction in the GA group), 15 min before cross-clamping, and 1,5, and 10 min after cross-clamping. There was a large (P < 0.05) increase in NE and E in the GA group by 15 min before aortic cross-clamping, but NE and E levels in the LEA group did not increase. The GA group had significantly higher levels of NE and E than the LEA group 15 min before cross-clamping and also after clamping. NE levels in the LEA group increased after cross-clamping, and NE levels in the GA group remained constant. E levels remained stable in both groups after cross-clamping. After clamping, SVR increased in both groups, but the increase occurred after 1 min in the GA group and took 5 min to become significant in the LEA group. There was no significant correlation between changes in NE or E and changes in SVR in either group. This study shows that epidural anesthesia to T4 prevents NE and E increases in response to abdominal surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of anesthetic induction and surgical incision on activated clotting time (ACT) was determined in patients undergoing vascular surgery. Patients undergoing carotid endarterectomy (CAE) (n = 50) and abdominal aortic aneurysm repair (AAA) (n = 45) were studied. Patients in the CAE group had cervical plexus block anesthesia, whereas patients in the AAA group had a combination of epidural and general anesthesia. The ACT was measured 1) before induction of anesthesia, 2) 5 min after induction, 3) 5 min after incision, 4) 5 min after heparinization, and 5) at the onset of skin closure. Heparin was reversed with protamine only if the ACT after revascularization was > 200 s. Reversal was considered adequate if the ACT was < 200 s and the surgeon felt that hemostasis was adequate. The ACT decreased by 12.26 +/- 1.23 (mean +/- SE) (P = 0.006) in the CAE group and by 12.47 +/- 1.01 (P = 0.002) in the AAA group with induction of anesthesia. There was a further decrease of 5.06 +/- 0.62 (P = 0.26) in the CAE group and 5.17 +/- 0.83 (P = 0.22) in the AAA group with incision. There was a significant difference in ACT in both groups from postinduction and postincision to skin closure (higher at skin closure). No patient in either group required additional protamine or clotting factors post-operatively, or return to the operating room for excessive bleeding. This study demonstrates that anesthetic induction with cervical block or epidural/general anesthesia decreases ACT.(ABSTRACT TRUNCATED AT 250 WORDS)

The physiologic effects of surgery as well as anesthesia on fluid balance have been discussed. Detailed discussions of some types of surgery and patient populations were included to clarify situations in which fluid management may be unusually difficult. Principles derived from the examination of these situations should make fluid management during the perioperative period easier

The effects of hetastarch and human albumin solutions on perioperative bleeding and coagulation parameters during abdominal aortic aneurysm repair were compared. In two randomized groups of 20 patients, albumin 5% (group 1) or hetastarch 6% (group 2) 1 g/kg was given during surgery. The remaining perioperative fluids consisted of lactated ringers and packed red blood cells. Perioperative coagulation measurements included partial thromboplastin time, prothrombin time, activated clotting time, platelet count, and bleeding time. Estimated blood loss and the total amount of crystalloid and blood infused were also measured. The surgeon, blind to the colloid used, subjectively rated bleeding on a scale of 1 to 10. There was no significant difference between groups for any measured parameter at any time. Measurements of coagulation function were within normal limits for both groups. Hetastarch does not cause clotting disorders in patients undergoing abdominal aortic aneurysm repair, at least if the quantities used in this study are not exceeded.