A systematic review of pulse pressure variation and stroke volume variation to predict fluid responsiveness during cardiac and thoracic surgery

This systematic review aims to summarize the published data on the reliability of pulse pressure variation (PPV) and stroke volume variation (SVV) to predict fluid responsiveness in an open-chest setting during cardio-thoracic surgery. The analysis included studies reporting receiver operating characteristics or correlation coefficients between PPV/SVV and change in any hemodynamic variables after a fluid challenge test in open-chest conditions. The literature search included seven studies. Increase in cardiac index and stroke volume index after a fluid challenge were the most adopted end-point variables. PPV and SVV showed similar area under the receiver operating characteristic curve values but high heterogeneity among studies. Cardiac and thoracic studies did not differ between PPV/SVV pooled area under the receiver operating characteristic curve. Studies exploring correlation between dynamic indices and end-point variable increase after fluid challenge showed conflicting results. The great heterogeneity between studies was due to small sample size and differences among protocol designs (different monitor devices, mechanical ventilation settings, fluid challenge methodologies, surgical incisions, and end-point variables). PPV and SVV seem to be inaccurate in predicting fluid responsiveness in an open-chest setting during cardio-thoracic surgery. Given the high heterogeneity of published data, more studies are needed to define the role of PPV/SVV in this context.