The ClearSight system for postoperative arterial blood pressure monitoring after carotid endarterectomy: a validation study

Background The majority of postoperative events in patients undergoing carotid endarterectomy(CEA) are of hemodynamic origin, requiring preventive strict postoperative arterial blood pressure(BP) control. This study aimed to assess whether BP monitoring with non-invasive beat-to-beat ClearSight finger BP(BPCS) can replace invasive beat-to-beat radial artery BP(BPRAD) in the postoperative phase. Methods Single-centre clinical validation study using a pre-specified study protocol. In 48 patients with symptomatic carotid artery stenosis, BPCS and BPRAD were monitored ipsilateral in a simultaneous manner during a 6-hour period on the recovery unit following CEA. Primary endpoints were accuracy and precision of BP derived by ClearSight(Edward Lifesciences,Irvine,CA,USA) versus the reference standard(Arbocath 20 G,Hospira,Lake Forest,IL,USA) to investigate if BPCS is a reliable non-invasive alternative for BP-monitoring postoperatively in CEA-patients. Validation was guided by the standard set by the Association for Advancement of Medical Instrumentation(AAMI), considering a BP-monitor adequate when bias(precision) is <5(8)mmHg. Secondary endpoint was percentage under- and overtreatment, defined as exceedance of individual postoperative systolic BP-threshold by BPRAD or BPCS in contrast to BPCS or BPRAD, respectively. Results The bias(precision) of BPCS compared to BPRAD was -10(13.6), 8(7.2) and 4(7.8) mmHg for systolic, diastolic and mean arterial pressure(MAP), respectively. Based on BPCS, undertreatment was 5.6% and overtreatment was 2.4%, however percentages of undertreatment quadrupled for lower systolic BP-thresholds. Conclusions Non-invasive MAP, but not systolic and diastolic BP, was similar to invasive BPRADduring postoperative observation following CEA, based on AAMI-criteria. However, as systolic BP is currently leading in postoperative monitoring to adjust BP-therapy on, BPcs is not a reliable alternative for BPRAD.