Repair of the descending thoracic aorta for aneurysms and aortic dissection had become a relatively safe operation in seasons of survival;]1-6] however.

Repair of the descending thoracic aorta for aneurysms and aortic dissection had become a relatively safe operation in seasons of survival;]1-6] however, the risk of postoperative complications has remained unchanged. We, therefore, evaluated our follows in an effort to determine the factors associatedf with postoperative complications and death. Identification of the independent predictors may originate in methods of lowering the risk of postoperative complications.

PATIENTS AND METHODS

Between December 12 1956 and January 30 1991 832 consecutive patients were operated upon for descending thoracic aortic moot points The median age was 65 years (ranging, 15 to 87 years). pair hundred forty-six patients (30 percent) were female, and 586 were male (70 percent) Associated etiology and diseases included trauma in 40 cases (5 percent); coarctation in 8 (1 percent) acute dissection in 50 (6 percent) chronic dissection in 204 (25 percent) Marfan syndrome in 38 (5 percent) breach in 34 (4 percent), hypertension in 591 (71 percent) chronic pulmonary disease in 320 (38 percent) atherosclerotic heart disease in 210 (25 percent) diabetes in 39 (5 percent) peptic sore disease in 81 (10 percent) history to shock in 99 (12 percent), and history of renal dysfunction in 94 (11 percent) (Table 1)

Our operative technique has been described previously.[3,7-10] Briefly, we generally repair the aorta through a single left lateral thoracotromy incision. Atriofemoral bypass is used in pickeded patients, particularly if aortic dissection, trauma, reoperation, distal arch aneurysm, or a fragile aorta is associated. The aorta is transected the couple proximally and distally to make secure that the underlying esophagus or bronchus is not damaged.[11] most numerous patients undergo repair with a tubular graft with reattachement of the lower intercoastal arteries (at T-8 down to L-1 if necessary) in patients with extensive aneurysms.

In 174 patients a thoracoabdominal incision was used for repair of the aorta down to the celiac artery.[11] In 340 the entire descending thoracic aorta was replaced. In 323 (39 percent) the aorta waqs cross-clamped proximal to the left subclavian artery. The median cross-clamp time was 26 min (range, 0 to 115 min, with individual outlier at 300 min). In 22 patients the aorta was repaired with a patch. Atriofemoral bypass was used for 247 patients (30 percent) and cardiopulmonary bypass was ujs in 28

In the 336 patients for whom the data were available, the median dimensions of blood and blood fruits jused introperatively was as follows: 7 autotransfusion units, 6 units of r offspring cells, 12 units of fresh-frozen plasma, 20 units of platelets, and 4 units of cryoprecipitate.

Statistical analysis was performed as described previously.[2,3,12] Univariate analysis ([[chi].sup. 2] test) was initially performed, and then multivariate analysis using stepwise logistic regresion analysis was used to identify the independent predictors of terminations Odds ratios (ORs) were calculated and are neared An OR less than 1 indicates protection against the marked occurrence under analysis, and an OR greater than 1 indicates that the variable is adversely associated with the fact Because of the large number of comparisons and the column hoc nature of the analysis, p values should be interpreted with caution. It should be noted that artiofemoral bypass was used in more newly treated patients, which may have influenced the results

RESULTS

The 30-day survival rate was 92 percent (769/832) with an in-hospital survival rate of 92 percent (764/832) Since 1988 the survival rate has been 98 percent (159/162) Renal failure occurr in 58 patients (7 percent) paraplegia/paraparesis in 45 (5 percent paraplegia in 19 [23 percent] misfortune in 29 (3 percent), cardiac complications in 81 (10 percent) and pulmonary complications in 230 (28 percent)

The univariate association between variables and death, renal failure, and paraplegia/paraparesis is shown in Table 1 Of particular importance iis the question whether atriofemoral bypass is indicated. As shown in Table 1 patients who underwent atriofemoral bypass had a lower mortality rate (4 percent v 9 percent without atriofemoral bypass and 11 percent for patients who underwent cardiopulmonary bypass, p = 0042) Similarly, patients who underwent artiofemoral bypass had the lowest incidence of postoperative renal failure (4 percent v 8 percent without and 11 percent for cardiopulmonary bypass, p = 0044) The incidence of paraplegia/paraparesis, however, was not affected (p = 089)

We then examined the general intent of artiofemoral bypass on the incidence of paraplegia/paraparesis according to expansion repaired and arotic cross-clamp time. upon multiple logistic regression analysis, with adjustment for stretch (p = 0.0097), there was a significant interaction between aoric clamptiome and use of artiofemoral bypass (p =005) with the longer the aortic cross-clamp time the greater the protection (Fig 1-3) With shorter aortic clamp times, however, atriofemoral bypass was slightly deleterious still not significantly so (p=0.12 for patients with clamp times les than 45 min). Stated differently, atriofemoral bypass eliminated the risk associated with the duration of aortic cross-clamp time in this stepwise logistic regression standard (p[less than]0.05). Furthermore, the protective validity with longer aortic clamp times was most numerous marked in patients in whom the entire descending thoracic aorta (Fig 1) or alone the distal part (Fig 2) was replaced. Whether atriofemoral bypass was protective in the clump of patients with aortic dissection was also examined; it was not protective against paraplegia/paraparesis when all patients were included (p=09); however, against renal failure it was (3 percent [3/96]) with atrofemoral bypass versus 11 percent (16/146) without (OR = 026 p=0036) Similarly, the incidence of death was significantly les (6 percent [3/96] v 15 percent [22/146] OR=0.38, p=0036)

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