Kubitz J C, Annecke T, Forkl S, Kemming G I, Kronas N, Goetz A E, Reuter D A
Department of Anesthesiology, Insitute for Surgical Research, Ludwig Maximillians University Munich, and Hamburg-Eppendorf University Hospital, Hamburg, Germany.
Br J Anaesth. 2007 May;98(5):591-7. doi: 10.1093/bja/aem062.
Left ventricular stroke volume variation (SVV) or its surrogates are useful tools to assess fluid responsiveness in mechanically ventilated patients. So far it is unknown, how changes in cardiac afterload affect SVV. Therefore, this study compared left ventricular SVV derived by pulse contour analysis with SVV measured using an ultrasonic flow probe and investigated the influence of cardiac afterload on left ventricular SVV.
In 13 anaesthetized, mechanically ventilated pigs [31(SD 6) kg], we compared cardiac output (CO), stroke volume (SV), and SVV determined by pulse contour analysis and by an ultrasonic aortic flow signal (Bland-Altman analysis). After obtaining baseline measurements, cardiac afterload was increased using phenylephrine and decreased using adenosine (both continuously administered). Measurements were performed with a constant tidal volume (12 ml kg-1) without PEEP.
Neither increasing mean arterial pressure (MAP) [from 59 (7) to 116 (19)] nor decreasing MAP [from 63 (7) to 39 (4)] affected CO, SV, and SVV (both methods). Method comparison revealed a bias for SVV of 0.1% [standard error of the mean (SE) 0.8] at baseline, -1.2% (SE 0.8) during decreased and 4.0% (SE 0.7) during increased afterload, the latter being significantly different from the others (P<0.05). Thereby, pulse contour analysis tended to underestimate SVV during decreased afterload and to overestimate SVV during increased afterload. Limits of agreement were approximately 6% for all points of measurement.
Left ventricular SVV is not affected by changes in cardiac afterload. There is a good agreement of pulse contour with flow derived SVV. The agreement decreases, if afterload is extensively augmented.
左心室每搏量变异（SVV）或其替代指标是评估机械通气患者液体反应性的有用工具。目前尚不清楚心脏后负荷的变化如何影响SVV。因此，本研究比较了通过脉搏轮廓分析得出的左心室SVV与使用超声流量探头测量的SVV，并研究了心脏后负荷对左心室SVV的影响。
在13头麻醉、机械通气的猪（体重31（标准差6）kg）中，我们比较了通过脉搏轮廓分析和超声主动脉血流信号测定的心输出量（CO）、每搏量（SV）和SVV（布兰德-奥特曼分析）。在获得基线测量值后，使用去氧肾上腺素增加心脏后负荷，使用腺苷降低心脏后负荷（均持续给药）。在无呼气末正压的情况下以恒定潮气量（12 ml/kg）进行测量。
无论是平均动脉压（MAP）升高[从59（7）升至116（19）]还是降低[从63（7）降至39（4）]，均不影响CO、SV和SVV（两种方法）。方法比较显示，基线时SVV的偏差为0.1%[平均标准误差（SE）0.8]，后负荷降低时为-1.2%（SE 0.8），后负荷增加时为4.0%（SE 0.7），后者与其他两者有显著差异（P<0.05）。因此，脉搏轮廓分析在心脏后负荷降低时往往低估SVV，在心脏后负荷增加时往往高估SVV。所有测量点的一致性界限约为6%。
左心室SVV不受心脏后负荷变化的影响。脉搏轮廓分析与流量衍生的SVV有良好的一致性。如果后负荷大幅增加，一致性会降低。
