Effect of Positive end-expiratory pressure on stroke volume variation: an experimental study in dogs

Background : Stroke volume variation (SVV) is reportedly affected by ventilation settings. However, it is unclear whether positive end-expiratory pressure (PEEP) affects SVV independent of the effect of driving pressure. We aimed to investigate the effect of driving pressure and PEEP on SVV under various preload conditions using beagle dogs as the model animal. Methods : Mild and moderate hemorrhage models were created in 9 anesthetized, mechanically ventilated beagle dogs by sequentially removing 10 mL/kg, and then an additional 10 mL/kg of blood, respectively. In all animals, driving pressure was incrementally increased by 4 cmH 2 O, from 5 cmH 2 O to 17 cmH 2 O, under PEEP values of 4, 8, and 12 cmH 2 O. Stroke volume (SV) was measured using the pulse-counter method and the thermodilution method. Results : The driving pressure did not significantly decrease SV under each preload condition and PEEP; however, increased SVV significantly. In contrast, the increased PEEP decreased SV and increased SVV under each preload condition and driving pressure, but these association were not statistically significant. According to multiple regression analysis, an increase in PEEP and decrease in preload significantly decreased SV (P<0.01). In addition, PEEP did not affect SVV, but the increased driving pressure and decreased preload significantly increased SVV. Conclusion: The SV decreased with an increase in PEEP; however, the SVV was not significantly affected by PEEP. Driving pressure had more influence than PEEP on SVV.