Accuracy of Stop-Cursor Method for Determining Systolic and Pulse Pressure Variation

Abstract

Functional hemodynamic indicators (systolic pressure variation [SPV and SPV%] and pulse pressure variation [PPV%]) are sensitive and specific indicators of fluid responsiveness. It was unknown if these indicators could be accurately measured directly from the bedside monitor. Determine the accuracy of SPV, SPV%, and PPV% measurements by using a stop-cursor method compared with a digitized analog strip (gold standard). A prospective observational study using a convenience sample of 30 adult patients in a medical-surgical intensive care unit who were receiving mechanical ventilation and had no spontaneous breaths during 3 sequential ventilator breaths and had an optimized arterial catheter. The peak and nadir arterial pressure values for a ventilator cycle were simultaneously obtained by using the stop-cursor method on the bedside monitor and a hardcopy strip. The indicators were averaged over 3 breaths, and the difference between methods was calculated. Data were analyzed from 29 patients (1 patient excluded) on assist control ventilation (mean [SD] for tidal volume, 7.5 [2] mL/kg; positive end-expiratory pressure, 7 [4] cm H2O). For SPV, the mean bias was 0.4 (SD, 0.9) mm Hg (95% limits of agreement [LOA], -1.4 to 2.2 mm Hg); for SPV%, 0.3 (SD, 0.9; 95% LOA, -1.5% to 2.1%); for PPV%, 1.0 (SD, 3.3; 95% LOA, -5.5% to 7.5%). In only 1 case (PPV%) was there disagreement on fluid response characterization. Statistically significant small differences in SPV and SPV% were detected. The differences in SPV, SPV%, and PPV% were not clinically significant, suggesting that functional hemodynamic indicators can be obtained accurately with the stop-cursor method.