A modified breathing pattern improves the performance of a continuous capnodynamic method for estimation of effective pulmonary blood flow

Abstract

In a previous study a new capnodynamic method for estimation of effective pulmonary blood flow (COEPBF) presented a good trending ability but a poor agreement with a reference cardiac output (CO) measurement at high levels of PEEP. In this study we aimed at evaluating the agreement and trending ability of a modified COEPBF algorithm that uses expiratory instead of inspiratory holds during CO and ventilatory manipulations. COEPBF was evaluated in a porcine model at different PEEP levels, tidal volumes and CO manipulations (N = 8). An ultrasonic flow probe placed around the pulmonary trunk was used for CO measurement. We tested the COEPBF algorithm using a modified breathing pattern that introduces cyclic end-expiratory time pauses. The subsequent changes in mean alveolar fraction of carbon dioxide were integrated into a capnodynamic equation and effective pulmonary blood flow, i.e. non-shunted CO, was calculated continuously breath by breath. The overall agreement between COEPBF and the reference method during all interventions was good with bias (limits of agreement) 0.05 (−1.1 to 1.2) L/min and percentage error of 36 %. The overall trending ability as assessed by the four-quadrant and the polar plot methodology was high with a concordance rate of 93 and 94 % respectively. The mean polar angle was 0.4 (95 % CI −3.7 to 4.5)°. A ventilatory pattern recurrently introducing end-expiratory pauses maintains a good agreement between COEPBF and the reference CO method while preserving its trending ability during CO and ventilatory alterations.

DOI: 10.1007/s10877-016-9891-z

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Cite this paper

@article{Sander2016AMB, title={A modified breathing pattern improves the performance of a continuous capnodynamic method for estimation of effective pulmonary blood flow}, author={Caroline H{\"a}llsj{\"{o} Sander and Th{\'o}rir Svavar Sigmundsson and Magnus Hallb{\"a}ck and Fernando Su{\'a}rez Sipmann and Mats K.E.B. Wallin and Anders Oldner and H{\aa}kan Bj{\"{o}rne}, journal={Journal of Clinical Monitoring and Computing}, year={2016}, volume={31}, pages={717-725} }