Correlation of systolic pressure variation, pulse pressure variation and stroke volume variation in different preload conditions following a single dose mannitol infusion in elective neurosurgical patients
Abstract Background: A Prospective observational study was designed assess the correlation between arterial pressure waveform derived indices and echocardiography derived stroke volume variation (SVV) at different preload conditions in patients undergoing elective craniotomies. Methods: Systolic pressure variation (SPV) and pulse pressure variation (PPV) were calculated from the arterial waveform. SVV was measured from transoesophageal echocardiography. After measuring baseline values for all three parameters, 1 g/kg of mannitol infusion (20%) was given over 15–20 min. Repeated measurements of SPV, PPV, SVV, urine output and peak airway pressure were done at the interval of 15, 30, 60, 90 and 120 min after stopping mannitol infusion. Pearson correlation coefficient (level of significance), and receiver operating characteristics curve were used for statistical analysis. Results: Significant correlation was present between SPV and SVV throughout the study. Significant correlation between SPV and PPV was present only at 90 min and 2 h after mannitol. The predictive effect of SPV and PPV in differentiating a volume loss ≥10 mL/kg was better than SVV. The best cut-off values for SPV, PPV and SVV were 12%, 9% and 20%, respectively. Conclusions: During mechanical ventilation with a tidal volume of 8 mL/kg, SPV correlated significantly with SVV at different preload conditions following mannitol infusion. PPV correlated poorly with SVV. SPV and PPV correlated only in the presence of hypovolaemia.