| Objective Real-time measurement of respiratory variation in pulse oximeter plethys-mograph waveform amplitude (dPOP) is useful in assessing fluid loading responsive-ness.This study investigated the influence of the depth of tidal volume (Vt) on dPOP.Methods Prospective study in50surgery patients under general anesthesia, adopts theprinciple of self control, each patient has both the same anesthesia and interventional method.At a rate of10mL·kg-1·h-1for intravenous infusion of lactated ringer solution. Fast inducedfor endotracheal intubation. All patients were ventilated in a volume of8mL/kg at afrequency of12cycles/min, expiratory of1:2and PEEP of0. Anesthesia was maintained withcontinous inhalation anesthesia of isoflurane and remifentanil at a rate of2～8ng/L in orderto keep a CSI index between40and60.Waiting for three minutes when monitoring indexsmooth.Vt was varied (6,9,12mL/kg body weight) in random order. Each Vt maintained3minutes. Recorded the hemodynamic and respiratory dynamics index after intervention. Pulseoximeter plethysmographic wave and end tidal CO2wave were monitored by Photoelecticmonitor. HR、SBP、DBP、MAP、CI、SVI and SVV were recorded by NICOM. Results39cases of the50were included in the study.The CI and SVI of the12mL/kg were higher thanthat in the6mL/kg with statistically significant difference (P＜0.05). SVV、dPOP、Ppeak andPplat of the12mL/kg were higher than the6mL/kg with statistical significance (P＜0.05).SVV、dPOP、Ppeak and Pplat of the9mL/kg were higher than that in the6mL/kg withstatistical significance (P＜0.05). SVV、dPOP、Ppeak and Pplat of the12mL/kg were higherthan that in the9mL/kg with statistical significance (P＜0.05).There were a significant relationship between dPOP and SVV (r=0.684, r=0.817, r=0.699; P＜0.05). The samerelationship between dPOP and Vt (r=0.428, r=0.638, r=0.543; P＜0.05). Conclusions Asan non-invasive prediction of fluid loading responsiveness, depth of Vt were significantlyrelated with it.Larger or smaller Vt will lead to wrong results. |
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