Weiss B M, Spahn D R, Rahmig H, Rohling R, Pasch T
Department of Anaesthesiology, University Hospital Zürich, Switzerland.
Br J Anaesth. 1996 Mar;76(3):405-11. doi: 10.1093/bja/76.3.405.
Radial artery tonometry provides continuous measurement of non-invasive arterial pressure (CNAP) by a sensor positioned above the radial artery. An inflatable upper arm cuff enables intermittent oscillometric calibration. CNAP was compared with invasive radial artery pressure recordings from the opposite wrist in 22 high-risk surgical patients with an inter-arm oscillometric mean arterial pressure difference < or = 10 mm Hg. Oscillometric, tonometric and invasive digital pressure values, and invasive and CNAP waveforms were obtained by the same instrument (Colin BP-508). Correlation coefficients (r) of invasive vs oscillometric values (n = 481 pairs) were 0.83, 0.90 and 0.92, and mean absolute errors of oscillometry were 7.6, 4.7, and 2.6 mm Hg for systolic, diastolic and mean arterial pressures, respectively. Correlation was poor for systolic (r = 0.80), diastolic (r = 0.77) and mean (r = 0.84) invasive vs CNAP values (n = 1375). Compared with oscillometry, mean absolute errors of 15.2, 10.9 and 9.4 mm Hg for systolic, diastolic and mean CNAP, respectively, were significantly (P < 0.001) higher. Mean prediction errors of CNAP, compared with invasive values, were -5.8 (SD 14.2) mm Hg for systolic, +7.2 (8.3) mm Hg for diastolic and +3.9 (8.8) mm Hg for mean arterial pressure. Individual patient accuracy of CNAP was assessed as good (individual prediction error < or = 5 (8) mm Hg and individual absolute error < or = 10 mm Hg) in seven patients, as acceptable (< or = 10 (12) and < or = 15 mm Hg) in 11 patients, and as inadequate in four of 22 patients. Individual accuracy of oscillometry was good or acceptable in all 22 patients. The trend in CNAP changes (difference between consecutive measurements) was sufficiently accurate during induction of anaesthesia, as only 47 (7.6%), 14 (2.3%) and 27 (4.4%) of 616 systolic, diastolic and mean CNAP values differed by more than 10 mm Hg of invasive pressure trends. We conclude that: intermittent oscillometry provides accurate arterial pressure monitoring; CNAP measurements offer a reliable trend indicator of pressure changes during induction of anaesthesia and may be considered an alternative to invasive pressure measurements, should arterial cannulation be difficult in an awake patient; and accuracy of absolute CNAP values is only moderate and unpredictable, thus radial artery tonometry should not replace invasive monitoring in high-risk patients during major surgical procedures.
通过置于桡动脉上方的传感器，桡动脉张力测量法可连续测量无创动脉压（CNAP）。一个可充气的上臂袖带用于间歇性示波法校准。在22例双臂示波法平均动脉压差值≤10mmHg的高危手术患者中，将CNAP与对侧手腕的有创桡动脉压记录进行比较。示波法、张力测量法和有创数字压力值，以及有创和CNAP波形均由同一台仪器（柯林BP - 508）获取。有创与示波法值（n = 481对）的相关系数（r）分别为0.83、0.90和0.92，示波法测量收缩压、舒张压和平均动脉压的平均绝对误差分别为7.6、4.7和2.6mmHg。有创与CNAP值（n = 1375）的收缩压（r = 0.80）、舒张压（r = 0.77）和平均压（r = 0.84）的相关性较差。与示波法相比，CNAP收缩压、舒张压和平均压的平均绝对误差分别为15.2、10.9和9.4mmHg，显著更高（P < 0.001）。与有创值相比，CNAP的平均预测误差为收缩压-5.8（标准差14.2）mmHg、舒张压+7.2（8.3）mmHg、平均动脉压+3.9（8.8）mmHg。22例患者中有7例的CNAP个体准确性被评估为良好（个体预测误差≤5（8）mmHg且个体绝对误差≤10mmHg），11例为可接受（≤10（12）且≤15mmHg），22例中有4例不充分。22例患者中所有患者的示波法个体准确性均为良好或可接受。在麻醉诱导期间，CNAP变化趋势（连续测量之间的差值）足够准确，因为在616个收缩压、舒张压和平均CNAP值中，只有47个（7.6%）、14个（2.3%）和27个（4.4%）与有创压力趋势的差值超过10mmHg。我们得出结论：间歇性示波法可提供准确的动脉压监测；CNAP测量为麻醉诱导期间的压力变化提供了可靠的趋势指标，并且如果清醒患者进行动脉置管困难，可被视为有创压力测量的替代方法；绝对CNAP值的准确性仅为中等且不可预测，因此在大手术过程中，桡动脉张力测量法不应取代高危患者的有创监测。
