2015, Number 2
Mean systemic pressure measurement and it’s correlation with the pulse pressure variation in critically ill patient
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ABSTRACTThe gradient between mean systemic pressure (PSM) and central venous pressure (CVP) is a major determinant of venous return and the pulse pressure variation (PPV) is a test that discriminates between patients who will or will not respond to volume challenge. The correlation between these variables has not been studied. The aim of this paper is to describe the hemodynamic profile and oxygen metabolism in four groups of patients classified by high or low values of each. In the period between October 2013 to June 2014, 26 PSM measurements were performed by the method of rapid inflation in 25 critically ill adult patients receiving mechanical ventilation in controlled mode. At the same time, hemodynamic profile and oxygen metabolism variables were measured. The median and interquartile range values (IQR) of the PSM were 25.5 mmHg (22-30). The corresponding values for the difference between PSM and CVP (CVP-PSM) were 14 mmHg (11-17); for PPV were 7.5% (5-10). Four sets of measurements were formed using the median as cutoff values: a) high PPV and low PSM-CVP, b) high VPP and high PSM-PVC, c) low PPV and low PSM-CVP, d) low PPV and high PSM-CVP. There was no association between PPV and PSM-CVP. There were no significant differences in hemodynamic profile and metabolic parameters among the four groups. In the post hoc analysis, the group with systemic venous resistance index (IRVeS) high (› 4 mmHg/L.m2) showed a hemodynamic and metabolic profile consistent with hypoperfusion. There were no complications related to the procedure for measuring the PSM by the method of rapid inflation and the values have a good correlation with those calculated by Parkin’s equation. In conclusion, in patients presenting with a low PPV, the gradient PSM-CVP is not correlated with the PPV; it is necessary to increase the sample size and include patients with high PPV to determine whether this correlation can provide information that will characterize groups of patients with different pathophysiological hemodynamic patterns. PSM measurement by rapid inflation method is easy and safe.
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