The effect of variable arterial transducer level on the accuracy of pulse contour waveform-derived measurements in critically ill patients

• Published in: Journal of clinical monitoring and computing Vol. 30; no. 5; pp. 569 - 575
• Main Authors: He, Huai-wu, Liu, Da-wei, Long, Yun, Wang, Xiao-ting, Zhao, Mei-ling, Lai, Xiao-li
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.10.2016; Springer Nature B.V
• Subjects: Adult; Aged; Anesthesiology; Arterial Pressure; Arteries - pathology; Blood Pressure; Cardiac Output; Critical Care - methods; Critical Care Medicine; Critical Illness; Female; Health Sciences; Heart Rate; Hemodynamics; Humans; Intensive; Male; Mathematical models; Medicine; Medicine & Public Health; Middle Aged; Monitoring; Monitoring, Physiologic - methods; Original Research; Parameters; Patients; Pressure; Prospective Studies; Pulse; Reproducibility of Results; Shape; Statistics for Life Sciences; Stroke Volume; Systole; Transducers; Critical care; Continuous hemodynamic monitoring; Arterial blood pressure transducer; Phlebostatic axis; Pulse contour waveform-derived measurements
• ISSN: 1387-1307; 1573-2614
• DOI: 10.1007/s10877-015-9756-x

We know that a 10 cm departure from the reference level of pressure transducer position is equal to a 7.5 mmHg change of invasive hemodynamic pressure monitoring in a fluid-filled system. However, the relationship between the site level of a variable arterial pressure transducer and the pulse contour-derived parameters has yet to be established in critically ill patients. Moreover, the related quantitative analysis has never been investigated. Forty-two critically ill patients requiring PiCCO-Plus cardiac output monitoring were prospectively studied. The phlebostatic axis was defined as the zero reference level; the arterial pressure transducer was then vertically adjusted to different positions (+5, +10, +15, +20, −20, −15, −10, −5 cm) of departure from the zero reference site. The pulse contour waveform-derived parameters were recorded at each position. Elevation of the pressure transducer caused significantly positive changes in the continuous cardiac index (+CCI), stroke volume index (+SVI), and stroke volume variation (+SVV), and negative changes in the rate of left ventricular pressure rise during systole (−dP/dtmax), the systemic vascular resistance index (−SVRI), and vice versa. At the 5 cm position, the SVRI changes reached statistical significance with error. At the 10 cm position, the changes in CCI and dP/dtmax reached statistical significance with error, while the change in SVV reached statistical significance at 15 cm. The change rate of CCI was more than 5 % at the 15 cm position and approximately 10 % at the 20 cm position. On average, for every centimeter change of the transducer, there was a corresponding 0.014 L/min/m 2 CCI change and 0.36 % change rate, a 1.41 mmHg/s dP/dtmax change and 0.13 % change rate, and a 25 dyne/s/cm 5 SVRI change and 1.2 % change rate. The variation of arterial transducer position can result in inaccurate measurement of pulse contour waveform-derived parameters, especially when the transducer’s vertical distance is more than 10 cm from the phlebostatic axis. These findings have clinical implications for continuous hemodynamic monitoring.