Effect Of Dynamic Hemodynamic Parameters In Predicting Fluid Responsiveness During Different Positive End-expiratory Pressure In Prone Position

Objective To investigate the effect of different positive end-expiratory pressures (PEEP) on dynamic hemodynamic parameters in patients lying in prone position during operation under general anesthesia.Methods 60 patients undergoing lumbar vertebra operation were studied. All patients were monitored with Vigileo/FloTrac system. The functional hemodynamic parameters including stroke volume variation (SVV) and pulse pressure variation (PPV), pleth variability index(PVI), etc. under PEEP levels of 0 cmH20,5 cmH20, 10 cmH20,15cmH2O were recorded before and after volume expansion (Hydroxyethyl Starch 6%,7 ml/kg). Fluid responsiveness was defined as an increase in stroke volume index(SVI)≥15%(△SVI≥15%). Responders were defined as patients demonstrating an increase in SVI≥=15% after intravascular volume expansion (VE) and non-responders as patients whose SVI changed< 15%. Receiver operating characteristic (ROC) curves were generated for SVV, PPV and PVI under different PEEP to determine their diagnosis accuracy and thresholds and their correlation.Results In the prone position, SVV, PPV and PVI were increased compared to those in the supine position(P<0.05),but mean arterial pressure(MAP) was decreased(P<0.05) and the changes of heart rate(HR), stroke volume(SV),stroke volume index(SVI), cardiac output(CO), cardiac index(CI) have no significance (P>0.05). In the prone position, along with the elevation of PEEP (0 cmH2O,5 cmH2O,10 cmH2O,15 cmH20), the area under the receiver operating characteristics (ROC) curves of SVV were 0.864,0.759,0.718,0.521, the area under the ROC of PPV were 0.873,0.792,0.705,0.505, and the area under the ROC of PVI were 0.851,0.765,0.709,0.512.Under PEEP=0 cmH2O, the diagnostic thresholds of SVV, PPV, PVI were 10.5,11.5,13.5. Under PEEP=5 cmH2O, the diagnostic thresholds of SVV, PPV, PVI were 11.5,13.5,14.5. Under PEEP=10 cmH20, the diagnostic thresholds of SVV, PPV, PVI were 13.5,14.5,16.5. In the prone position, there was a significant correlation between SVV, PPV, PVI and PEEP(r=0.424、0.561、0.553, P<0.01).Conclusions SVV, PPV and PVI can predict fluid responsiveness similarly under the PEEP(0,5cmH2O,10cmH2O), the diagnostic thresholds of them were increased with the PEEP and their diagnosis accuracy were decreased with the PEEP. But under the PEEP(15cmH2O) SVV, PPV and PVI can’t predict fluid responsiveness accurately. In the prone position, there was a significant positive correlation between SVV. PPV. PVI and PEEP.