The ClearSight System for Postoperative Arterial Blood Pressure Monitoring After Carotid Endarterectomy: A Validation Study

Abstract

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 noninvasive beat-to-beat ClearSight finger BP (BPCS) can replace invasive beat-to-beat radial artery BP (BPRAD) in the postoperative phase.

Methods: This study was a single-center clinical validation study using a prespecified 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) vs. the reference standard (Arbocath 20 G, Hospira, Lake Forest, IL) to investigate if BPCS is a reliable noninvasive 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) mm Hg. 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) mm Hg 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: Noninvasive MAP, but not systolic and diastolic BP, was similar to invasive BPRAD during 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.

Keywords: ClearSight; arterial pressure; blood pressure; carotid endarterectomy; hypertension; noninvasive continuous arterial pressure measurement; postoperative monitoring.

Graphical Abstract

Figure 1.

Study flowchart. Flow of participants through the study. The study time frame is from the first 6 hours postoperative on the recovery unit.

Figure 2.

Bland–Altman plots systolic, diastolic, and mean arterial pressure—BP_CS and BP_RAD and corresponding scatterplots. Left: Bland–Altman plot of all 20-second systolic (a), diastolic (b), and mean arterial pressure (c) data points (n = 36 290). Solid line indicates mean difference (bias) and dashed lines are the upper and lower 95% limits of agreement. Right: Corresponding scatterplots of systolic, diastolic, and mean arterial pressure of BP_CS vs. BP_RAD with lines of identity (solid line is slope, dashed lines is ±5 mm Hg, and dotted lines ±13 mm Hg indicating the AAMI validation borders). Abbreviations: BP, blood pressure; AAMI, Advancement of Medical Instrumentation.

Figure 3.

Bland–Altman plot systolic arterial pressure BP_CS and BP_RAD with over- and undertreatment. Scatter plot with on the y-axis the difference between systolic BP by ClearSight compared to individual systolic threshold of patient (mm Hg). x-axis: the difference between systolic BP by radial artery cannula and individual systolic threshold. All potentially overtreatment when using Clearsight is plotted in upper left quadrant (1), and all potentially undertreatment when using ClearSight is presented in lower right square (4). Abbreviation: BP, blood pressure.