WHAT THIS PAPER ADDSA validated prediction model for prevention of cerebral hyperperfusion syndrome (CHS) following carotid endarterectomy (CEA) is lacking; however, early recognition of cerebral hyperperfusion (CH) is crucial to prevent this complication. Intra-operative transcranial Doppler (TCD) is the gold standard to predict the risk of CH in CEA patients under general anaesthesia, but this study finds that post-operative TCD 24 h after CEA is more effective at predicting CH and CHS and is excellent at identifying patients NOT at risk of CHS after CEA. This has clinical relevance for cerebral monitoring protocols in centres performing CEA under general anaesthesia.Objectives: Intra-operative transcranial Doppler (TCD) is the gold standard for prediction of cerebral hyperperfusion syndrome (CHS) in patients after carotid endarterectomy (CEA) under general anaesthesia. However, post-operative cerebral perfusion patterns may result in a shift in risk assessment for CHS. This is a study of the predictive value of additional post-operative TCD measurements for prediction of CHS after CEA. Methods: This was a retrospective analysis of prospectively collected data in patients undergoing CEA with available intra-and post-operative TCD measurements between 2011 and 2016. The mean blood flow velocity in the middle cerebral artery (MCAV mean ) was measured pre-operatively, intra-operatively, and postoperatively at two and 24 h. Intra-operative MCAV mean increase was compared with MCAV mean increase two and 24 h post-operatively in relation to CHS. Cerebral hyperperfusion (CH) was defined as MCAV mean increase ! 100%, and CHS as CH with the presence of headache or neurological symptoms. Positive (PPV) and negative predictive values (NPV) of TCD measurements were calculated to predict CHS. Results: Of 257 CEA patients, 25 (9.7%) had CH intra-operatively, 45 (17.5%) 2 h post-operatively, and 34 (13.2%) 24 h post-operatively. Of nine patients (3.5%) who developed CHS, intra-operative CH was diagnosed in two and post-operative CH in eight (after 2 h [n ¼ 5] or after 24 h [n ¼ 6]). This resulted in a PPV of 8%, 11%, and 18%, and a NPV of 97%, 98%, and 99% for intra-operative, 2 h and 24 h post-operative TCD, respectively. Conclusions: TCD measurement of the MCAV mean 24 h after CEA under general anaesthesia is most accurate to identify patients who are not at risk of CHS.

Objectives: Transcranial Doppler (TCD) plays a crucial role in the intraoperative detection of patients at risk for cerebral hyperperfusion (CH) following carotid endarterectomy (CEA) under general anesthesia. However, cerebral perfusion patterns in the postoperative phase may lead to different risk assessment. The aim of this study was to determine the diagnostic value of additional postoperative TCD measurements after CEA for predicting CH and cerebral hyperperfusion syndrome (CHS).Methods: Patients who underwent a CEA with preoperative, intraoperative, and postoperative TCD monitoring between December 2011 and June 2016 were included. In 257 patients the mean velocity (Vmean) was measured preoperatively (V1), preclamping (V2), postdeclamping (V3), and 2 hours (V4) and 24 hours (V5) postoperatively using TCD. The intraoperative Vmean increase ([V3-V2]/V2) was compared to the postoperative increase ([V4-V1]/V1) and ([V5-V1] /V1) in relation to CHS. TCD measured CH was defined as Vmean increase of >100%. CHS was defined as neurologic complaints in the presence of Vmean >100%.Results: Of the included patients, 23 (8.9%) had an intraoperative CH, 44 (17.1%) had CH 2 hours postoperatively, and 31 (12.1%) had CH 24 hours postoperatively. In nine patients (3.5%) CHS was diagnosed; two of these patients had an intraoperative CH and eight had postoperative CH (n ¼ 5, 2 hours; n ¼ 6, 24 hours). This results in a positive predictive value of 8.7% for intraoperative measurement, 11.4% for 2 hours postoperative measurement, and 19% for 24 hours postoperative measurement. Negative predictive values of TCD intraoperative, 2 hours and 24 hours postoperative were, respectively, 97%, 98.5%, and 98.7%.Conclusions: Compared with the gold standard neuromonitoring using intraoperative TCD parameters, this study showed that early (2 and 24 hours) postoperative TCD monitoring after CEA in the awake patient is more accurate in the identification of patients at risk for CH and CHS.