Impact of arterial extension lines on pulse contour

Impact of arterial extension lines on pulse contour derived stroke volume calculation Vossen R. 1, 2, Heerman J. 1, Allaert S. 1 , Moonen J. 3, Kalmar A. F. 1, 2 1 2 Dept of Anesthesia & Critical Care , Maria Middelares Hospital, Gent, Belgium Department of Anesthesiology, University Hospitals Leuven, Belgium 3 UZ BRUSSEL and Vrije Universiteit Brussel, Brussels, Belgium Background: Pulse contour analysis of arterial pressure signals permits minimally invasive assessment haemodynamic parameters such as stroke volume. The calculation, however, relies on a precise analysis of the waveform, and its accuracy may be vulnerable to artefacts introduced by changes in impedance characteristics due to extension lines. The aim of this study was to assess the impact of dedicated and nondedicated extension lines on the area under the curve of the systolic part of the pressure waveform (AUC), on the systolic (SP) and diastolic (DP) blood pressure and on the Pulsioflex-derived stroke volume (SV). Methods: After ethics committee approval, arterial pressure waveforms and Pulsioflex (Maquet, Rastatt, Germany) output of ten patients under general anaesthesia were recorded. Two types of extension lines were evaluated: a non-dedicated “perfusor” polyethylene line (B. Braun, Melsungen, Germany) of 150 cm, and a dedicated arterial pressure line (150 cm). No extension line Over a period of 10 seconds before and after interposition of the extension line, the AUC determined using dedicated software - and the SV was recorded. The AUC, Diastolic (DP) and systolic (SP) pressure and SV were compared using an unpaired T-test (significance level p<0. 05). Results and Discussion: After interposition of the non-dedicated extension line the mean(SD) DP remained 54(8) mm. Hg, the SP changed from 99(17) to 104(17) mm. Hg, the SV remained 76(11) ml, and the AUC remained 6. 3(2. 1) s. mm. Hg. After interposition of the dedicated extension line, the mean(SD) DP remained 54(8) mm. Hg, the SP changed from 107(11) to 104(13) mm. Hg, the SV changed from 74(12) to 77(20) ml and the AUC changed from 6. 9(1. 8) to 6. 7(1. 7) s. mm. Hg. None of the changes was statistically significant. Conclusion: While the use of extension lines should be limited, the impact on the accuracy of waveform-derived measurement of diastolic and systolic blood pressure, and stroke volume is minimal. extension line Figure 1: Sample of the arterial waveform with the AUC shown in green. The AUC is the time-pressure integral during the systolic phase. The AUC is calculated from the start of the systole to the dicrotic notch (dn).