Continuous Noninvasive Arterial Pressure Monitoring in Obese Patients During Bariatric Surgery: An Evaluation of the Vascular Unloading Technique (Clearsight system)

Abstract

BACKGROUND: Continuous monitoring of arterial pressure is important in severely obese patients who are at particular risk for cardiovascular complications. Innovative technologies for continuous noninvasive arterial pressure monitoring are now available. In this study, we compared noninvasive arterial pressure measurements using the vascular unloading technique (Clearsight system; Edwards Lifesciences Corp, Irvine, CA) with invasive arterial pressure measurements (radial arterial catheter) in severely obese patients during laparoscopic bariatric surgery. METHODS: In 35 severely obese patients (median body mass index, 47 kg/m2), we simultaneously recorded noninvasive and invasive arterial pressure measurements over a period of 45 minutes. We compared noninvasive (test method) and invasive (reference method) arterial pressure measurements (sampling rate 1 Hz = 1/s) using Bland-Altman analysis (accounting for multiple measurements per subject), 4-quadrant plot/concordance analysis (2-minute interval, 5 mm Hg exclusion zone), and error grid analysis (calculating the proportions of measurements in risk zones A–E with A indicating no risk, B low risk, C moderate risk, D significant risk, and E dangerous risk for the patient due to the risk of wrong clinical interventions because of measurement errors). RESULTS: We observed a mean of the differences (±SD, 95% limits of agreement) between the noninvasively and invasively assessed arterial pressure values of 1.1 mm Hg (±7.4 mm Hg, −13.5 to 15.6 mm Hg) for mean arterial pressure (MAP), 6.8 mm Hg (±10.3 mm Hg, −14.4 to 27.9 mm Hg) for systolic arterial pressure, and 0.8 mm Hg (±6.9 mm Hg, −12.9 to 14.4 mm Hg) for diastolic arterial pressure. The 4-quadrant plot concordance rate (ie, the proportion of arterial pressure measurement pairs showing concordant changes to all changes) was 93% (CI, 89%–96%) for MAP, 93% (CI, 89%–97%) for systolic arterial pressure, and 88% (CI, 84%–92%) for diastolic arterial pressure. Error grid analysis showed that the proportions of measurements in risk zones A–E were 89.5%, 10.0%, 0.5%, 0%, and 0% for MAP and 93.7%, 6.0%, 0.3%, 0%, and 0% for systolic arterial pressure, respectively. CONCLUSIONS: During laparoscopic bariatric surgery, the accuracy and precision of the vascular unloading technique (Clearsight system) was good for MAP and diastolic arterial pressure, but only moderate for systolic arterial pressure according to Bland-Altman analysis. The system showed good trending capabilities. In the error grid analysis, >99% of vascular unloading technique–derived arterial pressure measurements were categorized in no- or low-risk zones.

Perioperative non-invasive versus semi-invasive cardiac index monitoring in patients with bariatric surgery – a prospective observational study

“…The validity of non-invasive or semi-invasive CO measurements has been demonstrated in previous studies in different populations including normal-weight patient groups and surgical settings [11,[33][34][35]. In morbidly obese patients undergoing bariatric surgery, 4 prospective observational studies tested the performance of the vascular unloading technique for arterial blood pressure measurements [36][37][38][39]. While the one study did not demonstrate interchangeability between the Nexfin® system and Riva-Rocci/Korotkoff-derived blood pressure measurements in 33 patients [36], the other three studies could show clinically useful trend ability of the arterial pressure values [37][38][39].…”

“…Kurki et al were able to show that cannulation of the radial artery generally reduces the blood flow distal to the puncture site although to varying degrees between individuals [49]. We did not measure arterial pressure on both upper arms at baseline in order to identify potential pressure differences between the left and right arm as conducted in the study of Rogge et al [38]. However, contralateral measurement may have also introduced bias due to differences in vessel architecture.…”

“…In morbidly obese patients undergoing bariatric surgery, 4 prospective observational studies tested the performance of the vascular unloading technique for arterial blood pressure measurements [36][37][38][39]. While the one study did not demonstrate interchangeability between the Nexfin® system and Riva-Rocci/Korotkoff-derived blood pressure measurements in 33 patients [36], the other three studies could show clinically useful trend ability of the arterial pressure values [37][38][39]. Thus far, evidence on non-or semi-invasive CI measurements in the perioperative setting of bariatric surgery is limited to one case series and one prospective observational study [10,40].…”

Validation of noninvasive continuous arterial pressure measurement by ClearSight System™ during induction of anesthesia for cardiovascular surgery

“…First, when we reviewed our preserved data from 18 patients before data analysis, the characteristics of patients were similar to those in previous prospective studies. The exclusion criteria in previous studies included peripheral arterial disease, preoperative atrial fibrillation, and obesity (> BMI 30) [4,7,15,16], and such patients were also not included in our study. Second, when data are collected from the anesthetic record, the time to intubate may not be accurate.…”

Non-invasive measurement of pulse pressure variation using a finger-cuff method in obese patients having laparoscopic bariatric surgery

“…The online version of this article (https ://doi.org/10.1007/s1087 7-020-00614 -8) contains supplementary material, which is available to authorized users. good absolute and trending agreement with invasive AP measurements in obese patients having laparoscopic bariatric surgery [12]. However, the agreement between PPV Finger and PPV derived from an arterial catheter (PPV ART ) in obese patients having laparoscopic bariatric surgery is unknown.…”