IEEE Trans Biomed Eng. 2021 Jul;68(7):2067-2075. doi: 10.1109/TBME.2020.3020358. Epub 2021 Jun 17.
A miniaturized accelerometer can be incorporated in temporary pacemaker leads which are routinely attached to the epicardium during cardiac surgery and provide continuous monitoring of cardiac motion during and following surgery. We tested if such a sensor could be used to assess volume status, which is essential in hemodynamically unstable patients.
An accelerometer was attached to the epicardium of 9 pigs and recordings performed during baseline, fluid loading, and phlebotomy in a closed chest condition. Alterations in left ventricular (LV) preload alter myocardial tension which affects the frequency of myocardial acceleration associated with the first heart sound ( f). The accuracy of f as an estimate of preload was evaluated using sonomicrometry measured end-diastolic volume (EDV[Formula: see text]). Standard clinical estimates of global end-diastolic volume using pulse index continuous cardiac output (PiCCO) measurements (GEDV[Formula: see text]) and pulmonary artery occlusion pressure (PAOP) were obtained for comparison. The diagnostic accuracy of identifying fluid responsiveness was analyzed for f, stroke volume variation (SVV[Formula: see text]), pulse pressure variation (PPV[Formula: see text]), GEDV[Formula: see text], and PAOP.
Changes in f correlated well to changes in EDV[Formula: see text] ( r=0.81, 95%CI: [0.68, 0.89]), as did GEDV[Formula: see text] ( r=0.59, 95%CI: [0.36, 0.76]) and PAOP ( r=0.36, 95%CI: [0.01, 0.73]). The diagnostic accuracy [95%CI] in identifying fluid responsiveness was 0.79 [0.66, 0.94] for f, 0.72 [0.57, 0.86] for SVV[Formula: see text], and 0.63 (0.44, 0.82) for PAOP.
An epicardially placed accelerometer can assess changes in preload in real-time.
This novel method can facilitate continuous monitoring of the volemic status in open-heart surgery patients and help guiding fluid resuscitation.
微型加速度计可以整合到临时起搏器导线上，这些导线通常在心脏手术期间附着于心外膜，并在手术期间和之后提供心脏运动的连续监测。我们测试了这种传感器是否可用于评估血容量状态，这对血流动力学不稳定的患者至关重要。
将加速度计附着于 9 头猪的心外膜上，并在闭合胸腔条件下进行基线、液体负荷和抽血时的记录。左心室（LV）前负荷的变化改变心肌张力，从而影响与第一心音（f）相关的心肌加速度频率。使用超声心动描记术测量的舒张末期容积（EDV[公式：见正文]）评估 f 作为前负荷估计值的准确性。使用脉搏指数连续心输出量（PiCCO）测量（GEDV[公式：见正文]）和肺动脉闭塞压（PAOP）获得了用于比较的标准临床估计的整体舒张末期容积。分析了 f、每搏量变异（SVV[公式：见正文]）、脉压变异（PPV[公式：见正文]）、GEDV[公式：见正文]和 PAOP 识别液体反应性的诊断准确性。
f 的变化与 EDV[公式：见正文]的变化密切相关（r=0.81，95%CI：[0.68, 0.89]），GEDV[公式：见正文]（r=0.59，95%CI：[0.36, 0.76]）和 PAOP（r=0.36，95%CI：[0.01, 0.73]）也是如此。f 识别液体反应性的诊断准确性为 0.79[0.66, 0.94]，SVV[公式：见正文]为 0.72[0.57, 0.86]，PAOP 为 0.63（0.44, 0.82）。
附着于心外膜的加速度计可以实时评估前负荷的变化。
这种新方法可以促进心脏直视手术患者血容量状态的连续监测，并有助于指导液体复苏。
