Abstract:
Objective. Since pulse wave transit time (PWTT) shortens as pulmonary artery pressure (PAP) increases it was suggested as a potential non-invasive surrogate for PAP. The state of tidal lung filling is also known to affect PWTT independently of PAP. The aim of this retrospective analysis was to test whether respiratory gating improved the correlation coefficient between PWTT and PAP.Approach. In each one of five anesthetized and mechanically ventilated pigs two high-fidelity pressure catheters were placed, one directly behind the pulmonary valve, and the second one in a distal branch of the pulmonary artery. PAP was raised using the thromboxane A2 analogue U46619 and animals were ventilated in a pressure controlled mode (I:E ratio 1:2, respiratory rate 12/min, tidal volume of 6 ml kg-1). All signals were recorded using the multi-channel platform PowerLab®. The arrival of the pulse wave at each catheter tip was determined using a MATLAB-based modified hyperbolic tangent algorithm and PWTT calculated as the time interval between these arrivals.Main results. Correlation coefficient for PWTT and mean PAP wasr= 0.932 for thromboxane. This correlation coefficient increased considerably when heart beats either at end-inspiration (r= 0.978) or at end-expiration (r= 0.985) were selected (=respiratory gating).Significance. The estimation of mean PAP from PWTT improved significantly when taking the respiratory cycle into account. Respiratory gating is suggested to improve for the estimation of PAP by PWTT.
摘要:
由于脉搏波传导时间(PWTT)随着肺动脉压(PAP)的增加而缩短,因此建议将其作为PAP的潜在非侵入性替代品。潮气肺充盈的状态也已知独立于PAP影响PWTT。这项回顾性分析的目的是测试呼吸门控是否改善了PWTT和PAP之间的相关系数。在五只麻醉和机械通风的猪中,每只猪放置两个高保真压力导管,一个在肺动脉瓣的正后方,第二个在肺动脉的远端分支。使用血栓烷A2类似物U46619提高PAP,并以压力控制模式(I:E比率1:2,呼吸频率12/min,潮气量6ml/kg)。使用多通道平台PowerLab®记录所有信号。使用基于MATLAB的改进双曲正切算法确定每个导管尖端的脉搏波到达,并将PWTT计算为这些到达之间的时间间隔。血栓素的PWTT和平均PAP的相关系数为r=0.932。当选择吸气末(r=0.978)或呼气末(r=0.985)心跳时(=呼吸门控),该相关系数显着增加。因此,当考虑呼吸周期时,来自PWTT的平均PAP的估计显著改善。建议通过PWTT改善呼吸门控以估计PAP。