The relationship between arterial transducer level and pulse contour waveform-derived measurements

For hemodynamic monitoring, the pressure transducer is suggested to be fixed at the level of the phlebostatic axis in critically ill patients [1,2]. The correction and adjustment of pressure transducer are emphasized in central venous pressure monitoring in clinical practice. The exact position of the transducer is relatively easy to be ignored for invasive arterial blood pressure monitoring [3,4]. Improper position of the transducer may cause inaccurate value and shape of the arterial blood pressure wave, which would result in an invalid PiCCO (Pulsion Medical Systems AG, Munich, Germany) algorithm for pulse contour waveform-derived measurements. This study was conducted as a prospective quantitative evaluation of the relationship between arterial transducer level and pulse contour waveform-derived measurements. In total, 22 patients were enrolled in the 28-bed department of critical care medicine of a university hospital. All of the patients had a femoral artery catheter for PiCCO hemodynamic monitoring. The site of the phlebostatic axis was defined as the zero level (reference level). We moved the arterial pressure transducer up and down at eight different levels (−5 cm, −10 cm, −15 cm, −20 cm, 5 cm, 10 cm, 15 cm, 20 cm). At each level, continuous cardiac index (CCI), rate of left ventricular pressure rise during systole (dP/dtmax), and systemic vascular resistance index (SVRI) were simultaneously recorded. The elevation of pressure transducer caused significantly positive changes in CCI and negative changes in