Influence of Perioperative Hemodynamics on spinal cord ischemia in thoracoabdominal aortic repair

Background. The purpose of this study is to investigate the influence of perioperative circulation on spinal cord during the repair of descending thoracic or thoracoabdominal aortic aneurysms. Methods. From October 1999, 92 patients ( aged 66 +/- 13 years; 65 men) underwent the repair of descending thoracic ( n = 30) or thoracoabdominal aortic aneurysm ( Crawford I, 9; II, 14; III, 35; IV, 4). We measured the time duration of hypotension, defined as follows, and evaluated the relationship between the incidence of paraplegia and each duration: T1, systolic arterial pressure less than 80 mm Hg, or mean pressure less than 60 mm Hg during aortic cross-clamping; T2, distal aortic pressure less than 60 mm Hg during aortic cross-clamping; T3, systolic arterial pressure less than 80 mm Hg after coming off bypass; T4, systolic arterial pressure less than 80 mm Hg in the intensive care unit. Results. Hospital mortality was 8% ( 7 patients). Neurologic deficits occurred in 10 patients ( 10.9%). The T1 and T2 periods showed no difference between paraplegia cases ( group P) and normal cases ( group N). The T3 periods in both groups were 54 +/- 52 and 6.6 +/- 18, and the T4 periods were 62 +/- 89 and 2.3 +/- 14, respectively. The T3 and T4 periods in group P were significantly longer than in group N ( p < 0.0001). Multivariate analysis demonstrated that T3 was an independent risk factor for paraplegia. When divided according to body temperature, the T2 period under mild hypothermia was significantly longer in group P than in group N, as well as the T3 and T4 periods. Conclusions. Perioperative hemodynamics stability is of vital importance for spinal cord protection during thoracoabdominal aortic surgery. In particular, the duration of hypotension after coming off bypass was an independent risk factor for paraplegia.