Complex blunt aortic injury or repair: beneficial effects of cardiopulmonary bypass use

Abstract

Objective: To compare the outcomes and associated morbidity in patients with blunt aortic injury (BAI) repaired using cardiopulmonary bypass versus no bypass. Special consideration is given to the influence of bypass in the outcome of complex injuries or repair circumstances.

Summary background data: There are conflicting data concerning the utility of bypass techniques in the operative management of BAI, and controversy over the subject persists. During the last decade, surgeons at the authors' institution have undergone a change in philosophy concerning management of these injuries and began almost exclusively using cardiopulmonary bypass for the repair in 1996. This project explores the effects of this change in the management of BAI.

Methods: The records of all patients with BAI admitted to a level 1 trauma center over a period of 12 years were reviewed for demographics, injury characteristics, operative technique, and outcome. The bypass group was compared to the no bypass group with respect to morbidity and mortality. Those with a complex injury or repair (CI/R) were examined as a subgroup. CI/R was defined as the presence of an injury with extension proximal to the subclavian artery, involvement of branch vessels, or requirement of maneuvers interfering with anastomosis construction, such as cardiac massage.

Results: From January 1, 1990, to December 31, 2001, 91 patients were admitted to Wake Forest University Baptist Medical Center with BAI. Sixty-five of these underwent operative repair. Sixty (32 no bypass, 28 bypass) survived to the immediate postoperative period. Injury Severity Score was similar (33 no bypass, 31 bypass, P =.48), as was admission base deficit (-9.2 m Eq/L no bypass vs. -7.0 mEq/L B, P =.13). Paraplegia occurred in four (12%) of the no bypass group as opposed to 0 of the bypass group (P =.05). No patient in the bypass group experienced complications related to heparinization, and two (7%) experienced bypass-related complications (cerebral edema, femoral vein laceration). Mean clamp time for the entire group was 27 minutes. Examination of the 10 patients with CI/R who survived the operating room showed markedly longer clamp times (59 minutes vs. 22 minutes, P <.0001) and a higher rate of paraplegia/paresis (30% vs. 2%, P =.01) as compared to those without CI/R. Logistic regression demonstrated a significant relationship between increasing clamp time and the CI/R classification (P =.007). All three (100%) of the CI/R patients repaired via clamp-and-sew technique developed paraplegia, while none of the seven CI/R patients repaired on bypass developed neurologic changes (P =.008).

Conclusions: With the use of cardiopulmonary bypass in the repair of BAI, the incidence of paraplegia/paresis has fallen. While patients with typical injuries and uncomplicated repair can expect good results with either technique, cardiopulmonary bypass provides significant advantages in the repair of those with CI/R. With the use of bypass, no CI/R patient developed paraplegia, while all CI/R patients experienced paraplegia before bypass use. Although others have reported the importance of clamp time, in this series clamp time appeared largely to be a surrogate variable for complexity of injury.

Figure 1. Distribution of clamp times* in complex injury/repair (CI/R) patients and non-CI/R patients. Includes those not repaired using deep hypothermic circulatory arrest without cross-clamp.