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Open Access Highly Accessed Research article

Mixed venous O2 saturation and fluid responsiveness after cardiac or major vascular surgery

Arjan N Kuiper1, Ronald J Trof2 and AB Johan Groeneveld13*

Author Affiliations

1 Departments of Intensive Care, VU University Medical Centre, Amsterdam, The Netherlands

2 Departments of Intensive Care, Medisch Spectrum Twente, Enschede, The Netherlands

3 Departments of Intensive Care, Erasmus Medical Center, Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands

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Journal of Cardiothoracic Surgery 2013, 8:189  doi:10.1186/1749-8090-8-189

Published: 22 September 2013

Abstract

Background

It is unclear if and how SvO2 can serve as an indicator of fluid responsiveness in patients after cardiac or major vascular surgery.

Methods

This was a substudy of a randomized single-blinded clinical trial reported earlier on critically ill patients with clinical hypovolemia after cardiac or major vascular surgery. Colloid fluid loading was done for 90 min, guided by changes in pulmonary artery occlusion pressure (PAOP) or central venous pressure (CVP). Fluid responsiveness was defined as ≥15% increase in cardiac index (CI). Hemodynamics, including transpulmonary dilution-derived global end-diastolic volume index (GEDVI) and global ejection fraction (GEF), were measured and blood samples taken.

Results

Whereas baseline SvO2 (>70% in 68% of patients) did not differ, the SvO2 increased in patients responding to fluid loading (≥15% in CI in n = 26) versus those not responding (n = 11; P = 0.03). The increase in GEDVI was also greater in responders (P = 0.005). The area under the receiver operating characteristic curve for fluid responsiveness of changes in SvO2 was 0.73 (P = 0.007), with an optimal cutoff of 2%, and of those in GEDVI 0.82 (P < 0.001), while the areas did not differ. However, the value of SvO2 increases to reflect CI increases with fluid loading was greatest when GEF was ≤20% (in 53% of patients).

Conclusions

An increase in SvO2 ≥2%, irrespective of a relatively high baseline value, can thus be used as a monitor of fluid responsiveness in clinically hypovolemic patients after cardiac or major vascular surgery, particularly in those with systolic cardiac dysfunction. Fluid responsiveness concurs with increased tissue O2 delivery.

Keywords:
Fluid responsiveness; Mixed venous oxygen saturation; Pulmonary artery catheter; Global end-diastolic volume index; Transpulmonary thermodilution