Smolle Karl-Heinz, Schmid Martin, Prettenthaler Helga, Weger Christian
From the *Department of Internal Medicine and Intensive Care, University Hospital Graz, Graz, Austria; †Institute for Medical Engineering, University of Technology Graz, Graz, Austria; and ‡Department of Orthopaedic Surgery, University Hospital Graz, Graz, Austria.
Anesth Analg. 2015 Dec;121(6):1508-16. doi: 10.1213/ANE.0000000000000965.
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.
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.
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.
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.
在没有动脉置管的重症监护病房（ICU）患者中，无创连续血压监测可能非常有益。CNAP®监测仪（CNSystems Medizintechnik AG）采用容积钳夹法提供无创逐搏血压（BP）估计值，测量校准至肱动脉压力值的手指动脉压力。本研究的目的是在常规临床条件下，比较CNAP监测仪的无创血压估计值与通过桡动脉导管获得的有创血压（IBP）测量值，研究对象为未经挑选的内科ICU患者。
对40例成年患者同时测量IBP和无创CNAP血压（CBP）30分钟。采用考虑重复测量的Bland-Altman分析揭示CBP相对于IBP的准确性和精密度。使用汇总测量方法计算百分比误差并进行互换性检验。使用四象限图和极坐标图进行趋势分析，每个报告的统计计算使用n = 40例患者的样本量。
共分析了7200对CBP和IBP测量值。对于平均动脉压，准确性±精密度为4.6±6.7 mmHg（一致性界限为-8.7至17.8 mmHg），百分比误差为6.77%（95%置信区间[CI]，6.57%-6.97%）。3分钟间隔的趋势分析显示，变化在10%界限内时，一致性率为94.6%（95%CI，94.0%-95.2%；排除区10%），极坐标一致性率为99.50%（95%CI，99.48%-99.52%）。
在常规临床条件下，CNAP设备为未经挑选的内科ICU患者提供了可行的血压估计值。平均动脉压在相对于桡动脉压的准确性以及百分比误差方面符合互换性标准，并根据Critchley预定义标准显示出良好的趋势分析能力。
