Objectives Congestion is associated with worse outcomes in critically ill surgical patients but can be difficult to quantify noninvasively. We hypothesised that plasma volume status (PVS), estimated preoperatively using a validated formula that enumerates percentage change from ideal plasma volume (PV), would provide incremental prognostic utility after coronary artery bypass graft (CABG) surgery.
Methods In this retrospective cohort study, patients who underwent CABG surgery (1999–2010) were identified from a prospectively collected database. Actual ([1-haematocrit] x [a+(b x weight [kg])]) and ideal (c x weight [kg]) PV were obtained from equations where a, b and c are sex-dependent constants. Calculated PVS was then derived (100% x [(actual−ideal)/ideal]).
Results In 1887 patients (mean age 67±10 years; 79% male; median European System for Cardiac Operative Risk Evaluation [EuroSCORE] 4), mean PVS was −8.2±9%. While 8% of subjects had clinical evidence of congestion, a relatively increased PV (PVS >0%) was estimated in 17% and correlated with lower serum sodium, higher EuroSCORE and a diagnosis of diabetes mellitus. A PVS≥5.6% was optimally prognostic and associated with greater mortality (HR: 2.31, p=0.009), independently of, and incremental to, EuroSCORE, New York Heart Association class and serum sodium. A PVS≥5.6% also independently predicted longer intensive care (β: 0.65, p=0.007) and hospital (β: 2.01, p=0.006) stays, and greater postoperative renal (OR: 1.61, p=0.008) and arrhythmic (OR: 1.29, p=0.03) complications.
Conclusions Higher PVS values, calculated simply from weight and haematocrit, are associated with worse inpatient outcomes after CABG. PVS could help refine risk stratification and further investigations are warranted to evaluate the potential clinical utility of PVS-guided management in patients undergoing CABG.
- coronary artery disease surgery
- heart failure
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Contributors AM wrote the first draft of the manuscript. AM, MFB, AK and DOO performed the statistical analyses. DOO conceived the study and is a guarantor. All authors were involved in data acquisition and revision of the manuscript for important intellectual content.
Funding Dr Maznyczka (FS/16/74/32573), Dr Okonko (FS/14/77/30913) and Dr Barakat (FS/14/77/30913) are supported by the British Heart Foundation. Drs Okonko and Barakat are supported by the NIHR Biomedical Research Center at Guy’s and St Thomas' NHS Foundation Trust and King’s College London.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All data relevant to the study are included in the article.
Patient consent for publication Not required.