Key result
The CNAP device provided accurate noninvasive mean arterial pressure estimates compared to invasive radial monitoring, with a percentage error of 6.77% (95% CI 6.57-6.97%).
Why the study?
Does the CNAP device provide accurate continuous noninvasive arterial blood pressure readings compared to invasive radial artery measurements in medical ICU patients?
Observational (n=40)
Does the CNAP device provide accurate continuous noninvasive arterial blood pressure readings compared to invasive radial artery measurements in medical ICU patients?
Effect estimate: percentage error 6.77% (95% CI 6.57-6.97)
The CNAP device provides feasible and accurate noninvasive continuous blood pressure estimates compared to invasive radial arterial pressure in medical ICU patients.
CNAP supports feasible noninvasive BP monitoring in ICU; leaves open larger validation before practice adoption.
BACKGROUND: In cases of intensive care unit (ICU) patients without an arterial line, noninvasive continuous blood pressure monitoring could be very beneficial. The CNAP® monitor (CNSystems Medizintechnik AG) provides noninvasive, beat-to-beat blood pressure (BP) estimates using the volume clamp method to measure finger arterial pressure calibrated to brachial pressure values. The aim of this study was to compare noninvasive BP estimates of the CNAP monitor with invasive blood pressure (IBP) measurements obtained via a radial arterial catheter in unselected medical ICU patients under routine clinical conditions. METHODS: In 40 adult patients, IBP and noninvasive CNAP blood pressure (CBP) were measured simultaneously for 30 minutes. Bland-Altman analysis accounting for repeated measurements revealed accuracy and precision of CBP toward IBP. Percentage errors were calculated using the summary measures method and tested for interchangeability. Trending analysis was assessed using 4-quadrant plots and polar plots, whereby each reported statistical calculation used the sample size of n = 40 patients. RESULTS: A total of 7200 measurement pairs of CBP and IBP were analyzed. For mean arterial pressure, accuracy ± precision resulted in 4.6 ± 6.7 mm Hg (limits of agreement -8.7 to 17.8 mm Hg) with a percentage error of 6.77% (95% confidence interval [CI], 6.57%-6.97%). Trending analysis of 3-minute intervals showed a concordance rate of 94.6% (95% CI, 94.0%-95.2%; exclusion zone 10%) and a polar concordance rate of 99.50% (95% CI, 99.48%-99.52%) for changes lying within 10% limits. CONCLUSIONS: The CNAP device provided feasible estimates of BP in unselected medical ICU patients under routine clinical conditions. Mean arterial pressure met interchangeability criteria for accuracy toward radial arterial pressure, as well as for percentage error, and showed good trending capabilities according to the Critchley predefined criteria.
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Smolle et al. (2015) conducted an observational in Medical intensive care unit patients (n=40). CNAP monitor vs. Invasive radial artery catheter was evaluated on Mean arterial pressure accuracy and precision (percentage error) (percentage error 6.77%, 95% CI 6.57-6.97). The CNAP device provided accurate noninvasive mean arterial pressure estimates compared to invasive radial monitoring, with a percentage error of 6.77% (95% CI 6.57-6.97%).