Monitoring of pulse pressure variation using a new smartphone application (Capstesia) versus stroke volume variation using an uncalibrated pulse wave analysis monitor: a clinical decision making study during major abdominal surgery

Pulse pressure variation (PPV) and stroke volume variation (SVV) can be used to assess fluid status in the operating room but usually require dedicated advanced hemodynamic monitors. Recently, a smartphone application (Capstesia™), which automatically calculates PPV from a picture of the invasive arterial pressure waveform from any monitor screen (PPV_CAP), has been developed. The purpose of this study was to compare PPV_CAP with SVV from an uncalibrated pulse wave analysis monitor (SVV_PC). In 40 patients undergoing major abdominal surgery, we compared PPV_CAP with SVV_PC at post-induction, pre-incision, post-incision, end of surgery, and during every hypotensive episode (mean arterial pressure < 65 mmHg). We classified PPV_CAP and SVV_PC into three categories reflecting the thresholds used for the decision to administer fluids: no fluid administration (PPV and SVV < 9%), gray zone (PPV and SVV 9–13%), and fluid administration (PPV and SVV > 13%). The agreement between SVV_PC and PPV_CAP for these three categories was measured by the number of concordant paired measurements divided by the total number of paired measurements and Cohen’s kappa coefficient. In the 549 pairs of PPV–SVV data obtained, the overall agreement of PPV_CAP with SVV_PC was 79%, and the kappa coefficient was moderate (0.55). The highest agreement and kappa coefficient value were observed after the induction of anesthesia before surgical incision. PPV_CAP and SVV_PC would have resulted in completely opposite clinical decisions regarding fluid administration in 1% of the cases. In this clinical decision making study in patients undergoing major abdominal surgery, we observed a moderate agreement between PPV_CAP and SVV_PC with regard to categories used to guide fluid administration.

Trial Registration: Clinical Trials.gov (NCT03137901).