Volume assessment with central venous saturation compared to standard measure and bedside ultrasound
Munie S, Kandagatla P, Blyden D, Dereczyk D, and Killu K. Volume assessment with central venous saturation compared to standard measure and bedside ultrasound. Crit Care Med 2019; 47(1).
Crit Care Med
Learning Objectives: Hemodynamic assessment of critically ill patients is an integral daily task of an intensivist. Multiple parameters are evaluated to arrive at volume status of a patient. Central venous oxygen saturation (ScVO2) from central venous catheter is used as a surrogate for the oxygen supply/demand status of tissues and volume status. In this study, we evaluate the correlation of ScVO2 with volume status assessment using the standard clinical measures and the point of care ultrasound. Methods: A prospective, observational study at a surgical intensive care unit of a single academic tertiary center was performed. Patients were assessed for their volume status using standard measures and clinical impression as well as bedside ultrasound. The bedside ultrasound method included evaluating heart, lungs, IVC and internal jugular vein. Volume assessment by standard method included: heart rate, mean arterial pressure, central venous pressure, serum lactate and cardiac output/ index evaluation. ScVO2 values were measured from a blood gas obtained through an internal jugular or subclavian central catheter. Correlation between ScVO2 with the standard measures as well as bedside ultrasound were evaluated by spearman's correlation coefficient. Results: Sixty-one patients were included in the study. Thirty-seven (61%) were male, 39 (64%) were Caucasian and mean age was 59 years±14. ScVO2 threshold of 70% was used to divide hypovolemic and non-hypovolemic patients. The mean ScVO2 in hypovolemic patients was found to be 63.0%±12 and the mean in the non-hypovolemic patients was 75.2%±6.2 There was no correlation between ScVO2 and volume assessment using the standard measure (r=0.23, p=0.08) or point of care ultrasound (r=-0.11, p=0.40). Conclusions: ScVO2 alone should not be used to evaluate the volume status since the correlation with the standard clinical measures and point of care ultrasound to recognize hypovolemia was weak.