Preoperative hyponatremia predicts outcomes after cardiac surgery

Juan A. Crestanello, Gary Phillips, Michael S. Firstenberg, Chittoor Sai-Sudhakar, John Sirak, Robert Higgins, William T. Abraham

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: To study the effect of preoperative hyponatremia (Na <135 mEq/L) on outcomes after cardiac surgery. Methods: From 2002 to 2008, 4370 patients had cardiac surgery at our institution (CABG in 2238, valve in 597, CABG valve in 537, other in 998). The institution electronic medical records, STS database, and Social Security death index data were analyzed. The association of hyponatremia with mortality, hospital length of stay (LOS), and complications was analyzed using regression analysis. Results: Prevalence of hyponatremia was 21%. Patients with preoperative hyponatremia had lower left ventricular ejection fraction (39% ± 17% versus 46% ± 14%, P < 0.001) and glomerular filtration rate (69 ± 32 mg/min/1.73 m2 versus 74 ± 27 mg/min/1.73 m2, P < 0.001) and higher median EuroSCORE (19% versus 9%, P < 0.001), NYHA class 3-4 (77% versus 65%, P < 0.001), prevalence of chronic obstructive pulmonary disease (25% versus 18%, P < 0.001), and arteriopathy (20% versus 13%, P < 0.001). Hyponatremia was associated with increased early mortality (9% versus 4%, P < 0.001), late mortality (24% versus 16%, P < 0.001), and LOS (13 versus 8 d, P < 0.001). Mortality increased with the severity of hyponatremia. After adjusting for baseline and operative variables, hyponatremia was associated with increased hazard of mortality (hazard ratio [HR] 1.31, 95% confidence interval [CI] 1.14-1.52, P < 0.001), risk of early mortality (odds ratio [OR] 1.52, 95% CI 1.09-2.12, P < 0.001), late mortality (HR 1.37, 95% CI 1.16-1.62, P < 0.001), LOS (multiplier 1.26, 95% CI 1.15-1.39, P < 0.001), operative complications (OR 1.30, 95% CI 1.00-1.69, P = 0.051), and dialysis (OR 1.64, 95% CI 1.11-2.44, P = 0.013). Conclusions: Preoperative hyponatremia is common, especially in high-risk patients. It is an independent risk factor for mortality, prolonged hospitalization, and complications after cardiac surgery.

Original languageEnglish (US)
Pages (from-to)60-66
Number of pages7
JournalJournal of Surgical Research
Volume181
Issue number1
DOIs
StatePublished - May 1 2013
Externally publishedYes

Keywords

  • Cardiac surgery
  • Hyponatremia
  • Mortality
  • Outcomes
  • Risk factors
  • Serum sodium

ASJC Scopus subject areas

  • Surgery

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