A challenge with 5 cmH2O of positive end-expiratory pressure predicts fluid responsiveness in neurosurgery patients with protective ventilation: an observational study

Abstract

Background: Positive end-expiratory pressure (PEEP) increment induces a decrease in Stroke Volume Index (SVI). We hypothesized that the magnitude of SVI reduction due to a 5 cmH2O increase in PEEP could predict fluid responsiveness during low tidal volume ventilation.

Methods: Forty-eight patients completed the study. Heart rate, mean arterial pressure, SVI, pulse pressure variation (PPV) and stroke volume variation (SVV) were recorded before short-time low PEEP (SLPC) challenge (applied additional 5 cmH2O PEEP to patients for 30 seconds), during SLPC and before and after 500 mL fluid loading. Patients whose SVI increased more than 15% after the fluid loading were defined as volume responders.

Results: Twenty-one (44%) patients were volume responder. Decrease percentage in SVI during SLPC was 17.4±3.6% and 9.9±3.1% in responders and non-responders respectively (P<0.001). A strong correlation was found between decrease percentage in SVI during SLPC and increase percentage in SVI after fluid loading (R2=0.680, P<0.001). The area under receiver operating curves generated to predict fluid responsiveness for decrease percentage in SVI during SLPC (0.944, 95% CI: 0.836-0.990) was significantly higher than that for PPV (0.777, 95% CI: 0.634-0.884, P=0.025) and SVV (0.773, 95% CI: 0.630-0.882, P=0.022). Best cut-off values of decrease percentage in SVI during SLPC was -14.2 with 95% sensitivity and 89% specificity.

Conclusions: SVI change percentage during SLPC can predict fluid responsiveness better than PPV and SVV in neurosurgery patients ventilated with low tidal volume.