P48 RETROSPECTIVE POSTOPERATIVE NEAR INFRARED SPECTROSCOPY MONITORING ANALYSIS TO DETECT POTENTIAL CRITERIA TO IMPROVE POSTOPERATIVE PREDICTION OF UNFAVOURABLE OUTCOME FOLLOWING AORTIC SURGERY

Abstract

Abstract Objective Near Infrared Spectroscopy (NIRS) monitoring has become a frequent practice during aortic surgery. The real impact of NIRS in predicting postoperative outcomes, however is still debated, as many cases of “false negative” with severe cerebral damage despite apparently normal NIRS monitoring during surgical procedure. We applied extended retrospective postoperative NIRS monitoring analysis in order to investigate potential criteria to enhance postoperative unfavorable outcome prediction. Materials and Methods Data of NIRS monitoring of 41 patients undergoing aortic surgery (19 acute dissection) were retrospectively analyzed. Partial circulatory arrest with selective bilateral (21 pts) or unilateral (20 pts) cerebral perfusion (CP) was used in all patients. Double channel (R and L) NIRS value was continuously recorded (every 30 sec) from anaesthetic induction to patient’s transfer to ICU. Postoperatively all data were downloaded in excel format and retrospectively analyzed. Baseline, maximum, and minimum value with percentage drop and R/L channel gap were all analyzed considering 5 different phases of surgery: before extracorporeal circulation (EC); in EC before circulatory arrest and selective cerebral perfusion (CA–SCP); in EC following CA–SCP, following EC. Overall time <25% (in each channel) or with a > 20% gap were also evaluated. Results Overall 661±125 values were recorded for each patient. Baseline value on the Left (61±7) was significantly lower then Right (66±12). Maximum drop did not differed in two channels (Fig 1a) but varied according surgical phases (Fig 1). R/L asymmetry also varied according surgical phases with a peak value during rewarming and not during CA–SCP despite unilateral SCP and complexity of procedure (Figure 2 and 3). Conclusion Extended postoperative analysis of NIRS recorded value shows different trend and behavior according surgical phase and cerebral perfusion strategy. Accurate extended NIRS analysis is therefore mandatory in order to improve knowledge of physiological cerebral perfusion during SCP and early identification of patients at high risk of postoperative cerebral complications.