Pressure measurements in closed aneurysmal sac during abdominal aortic aneurysm resection

Purpose: This study determined the relationship between closed aneurysmal s ac pressure (ASP) and mean blood pressure (BP) during open abdominal aortic aneurysm (AAA) resection and evaluated the contribution of inferior mesent eric and lumbar artery blood flow to ASP after proximal and distal clamping . Methods: We measured ASP after proximal and distal clamping by placing an 1 8-gauge needle connected to a BP transducer into the excluded aneurysmal sa c in 25 consecutive patients from April 1999 to August 2000. Simultaneous m easurement of the mean systemic BP was also recorded. The ratio of ASP to m ean BP in relation to the number of actively bleeding lumbar arteries (N-LA ), diameter of the AAA (D-Cm), and volume of the thrombus in the AAA (Vol-T A) were recorded. Results: The mean ASP was 43.32 +/- 15.19 nim Hg, with an ASP to mean BP ra tio of 0.47 +/- 0.15. The N-LA in the closed aneurysmal sac ranged from 0 t o 6 (mean, 3.4 +/- 1.78). The D-Cm as determined by means of computed tomog raphy (CT) scan of the aorta ranged from 5 to 8 cm in its largest anteropos terior/transverse diameter. The average Vol-TA was 6.15 +/- 4.49 mL. Inferi or mesenteric artery blood flow contributed to ASP in three patients (12%). There was no correlation between ASP to mean BP ratios and the N-LA (P = . 127), D-Cm (P = .882), or Vol-TA (P = .252). Conclusion: Closed ASP and ASP ratios are highly variable and do not correl ate with N-LA, D-Cm, or the Vol-TA.