Estimating changes in Stroke Volume by non-invasive pulse-oximetry Pulse Transit Time Measurements

J. ten Bokkel-Andela, Marieke Poterman, Thomas Scheeren, A.F. Kalmar

Research output: Contribution to conferencePosterAcademic

Abstract

Background and Goal of Study: Pulse wave transit time (PTT), the interval between the R-wave peak on an electrocardiogram (ECG) and arrival of the pulse waves in the periphery (e.g. the finger), is reported to be a reliable estimate for stroke volume[1,2]. In this study, the PTT based on ECG and the non-invasive pulse-oximetry signal obtained at the right/left digit finger was calculated and its evolution after administration of a vasopressor or atropine. These values were compared with concomitant changes in stroke volume (ΔSV), as measured by volume-clamp plethysmography (Nexfin). 
Materials and Methods: PTT was measured in 60 patients under standardized propofol/remifentanil anesthesia during ophthalmic surgery. Patients received atropine if heart rate (HR) dropped below 60 bpm and randomly norepinephrine (10µg+0.05 µg.kg-1.min-1) or phenylephrine (100µg + 0.5µg. kg-1.min-1) if mean arterial pressure dropped >20% below normal awake values. After synchronisation of ECG- and Nexfin-derived waveforms, the PTT was determined beat-to-beat from 60 seconds before to 300 seconds after administration of the vasopressor or atropine (=t0 ). The median SV, HR and PTT at each administration were calculated at t0 and at t300 with a window of 30 seconds, and their respective relative changes determined. The relationship between ΔPTT and ΔSV, and between ΔPTT and ΔHR were depicted, and correlation was determined. 
Results and Discussion:ΔHR and ΔPTT correlated only moderately ( R2 = 0.3525, Fig. 1A). However, ΔSV and ΔPTT did not correlate at all ( R2 = 0.0036, fig. 1B).
Conclusion: In this study we induced changes in stroke volume by administration of vasopressors or atropine. Although a moderate correlation was shown between the ΔHR and ΔPTT, our results indicate that the Pulse Transit Time is not suitable to reliably estimate changes in stroke volume measured by Nexfin. 
References: 1. Kim et al, Anesthesia Analgesia 2013;116:94-100 2. Sugo et al., Conf Proc IEEE Eng Med Biol Soc. 2010;2853-6
Original languageEnglish
Pages7AP7-7
Publication statusPublished - 1-Jun-2015
EventEuroanaesthesia 2015 - Berlin, Germany
Duration: 30-May-20152-Jun-2016

Conference

ConferenceEuroanaesthesia 2015
CountryGermany
CityBerlin
Period30/05/201502/06/2016

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