Accuracy and precision of continuous, non‐invasive blood pressure devices: a systematic review and meta‐analyses

INTRODUCTION: Reliable continuous non-invasive blood pressure monitoring technology should support clinicians to maintain blood pressure within appropriate limits peri-operatively. Previous studies have shown conflicting results regarding measurement accuracy. METHODS: This systematic review and six meta-analyses evaluated the accuracy and precision of non-invasive continuous arterial blood pressure measurement technologies (volume clamp technology, applanation tonometry and photoplethysmography) compared with invasive arterial measurement in adults. We analysed pooled bias (mean difference between non-invasive and invasive measurement), standard deviation and limits of agreement. In each meta-analysis, mean arterial pressure (MAP), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were analysed separately. Acceptability was defined according to Association for the Advancement of Medical Instrumentation® (AAMI) criteria. RESULTS: Sixty-five studies were included: two meta-analyses for volume clamp technology (ClearSight™, CNAP™); three meta-analyses for applanation tonometry (T-Line™, Vasotrac™ and N-CAT™); and one meta-analysis for photoplethysmography technology. For volume clamp technologies, none met AAMI criteria for bias and SD in relation to MAP, SBP and DBP. T-Line, Vasotrac and N-CAT met the AAMI criteria for bias for MAP (2.53 mmHg, 0.36 mmHg, -0.37 mmHg), SBP (-0.07 mmHg, 1.20 mmHg, -3.68 mmHg) and DBP (3.09 mmHg, 1.09 mmHg, 0.84 mmHg), respectively. In terms of standard deviation, only N-CAT (MAP 6.97 mmHg, SBP 7.14, mmHg, DBP 6.55 mmHg) met AAMI criteria for all blood pressure parameters. Photoplethysmography technology met AAMI criteria for bias (MAP -0.09 mmHg, SBP 0.49 mmHg, DBP -0.26 mmHg) and standard deviation (MAP 6.86 mmHg, DBP 6.38 mmHg). DISCUSSION: Overall, the AAMI criteria for bias and SD were not fulfilled for most of the devices tested and wide limits of agreement are of concern. One applanation tonometry device (N-CAT) shows promise. Clinicians should be aware of the lack of interchangeability with invasive blood pressure management.