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PVSS13. Validation Of A New, Simple Subclassification Of ASA III Patients Undergoing Peripheral Revascularization Based On Functional Status

Hasan H. Dosluoglu, Leslie DeFranks-Anain, Nader D Nader. 
VA Western NY Healthcare System, SUNY at Buffalo, Buffalo, N.Y.  

OBJECTIVES: American Society of Anesthesiology (ASA) classification remains the most widely used risk stratification system in the world. However, it is not practical in patients undergoing revascularization procedures, since the vast majority is classified as ASA III. Modifications have been attempted to better identify subgroups, but none have been adopted. We hypothesized that ASA III patients could be subdivided into two subgroups, ASA IIIa and ASA IIIb, simply based on their preoperative functional status (> or than 4 METS), which would allow the largest group of vascular surgery patients to be appropriately subgrouped for their predicted postoperative morbidity and mortality.

METHODS: All charts of 482 patients (99% male) who underwent revascularization for disabling claudication or critical limb ischemia between 06/2001-10/2006 were reviewed for demographics, comorbidities, operative/interventional details, postoperative complications, and outcomes (MI/stroke, death). SPSS program was used for statistical analysis. Kaplan-Meier was used for survival, and Cox regression was used for multivariate analysis. Fisher’s exact test was used for group comparisons.

RESULTS: There were 35 patients in ASA II (7%), 371 patients (77%) in ASA III, and 76 patients in ASA IV (16%). ASA III patients were evenly distributed between ASA IIIA (45%), and ASA IIIB (32%). (Table 1). The age, albumin level, incidence of CAD, DM, cerebrovascular accident, renal insufficiency (Cr>1.5mg/dL), critical limb ischemia (CLI), and length of stay (LOS) were significantly higher in ASA IIIb than IIIa patients (Table 1). There were significantly more MI and death in IIIb patients than IIIa, with similar rates between IIIa vs. II and IIIb vs. IV (Table 2). The overall survival rates were significantly different in ASA IIIa and IIIb groups, IIIa being close to ASA II and IIIb close to ASA IV (Table 3, Figure 1). Cox regression analysis showed albumin <3g/dL, CLI, CAD, and renal insufficiency correlated with poor survival.

CONCLUSIONS: Functional status assessment is an integral part of routine preoperative anesthesia evaluation, and we found this to be very reliable in predicting not only postoperative morbidity and mortality, but overall survival in ASA III patients undergoing peripheral revascularization. This simple modification allows ASA III patients (80% of vascular patients) to be unbundled into two very distinct subgroups, which will potentially lead to a more appropriate preoperative risk assessment.

Figure 1. Overall Survival by Kaplan-Meier Analysis