Preoperative hyponatremia predicts outcomes after cardiac surgery

Division of Cardiac Surgery, Wexner Medical Center, The Ohio State University, Columbus, Ohio.
Journal of Surgical Research (Impact Factor: 2.12). 06/2012; 181(1). DOI: 10.1016/j.jss.2012.06.004
Source: PubMed

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 m(2)versus 74 ± 27 mg/min/1.73 m(2), 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.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hyponatraemia-the most common serum electrolyte disorder-has also emerged as an important marker of the severity and prognosis of important diseases such as heart failure and cirrhosis. Acute hyponatraemia can cause severe encephalopathy, but the rapid correction of chronic hyponatraemia can also profoundly impair brain function and even cause death. With the expanding elderly population and the increased prevalence of hyponatraemia in this segment of society, prospective studies are needed to examine whether correcting hyponatraemia in the elderly will diminish cognitive impairment, improve balance and reduce the incidence of falls and fractures. Given that polypharmacy is also common in the elderly population, the various medications that may stimulate arginine vasopressin release and/or enhance the hormone's action to increase water absorption must also be taken into consideration. Whether hyponatraemia in a patient with cancer is merely a marker of poor prognosis or whether its presence may alter the patient's quality of life remains to be examined. In any case, hyponatraemia can no longer be considered as just a biochemical bystander in the ill patient. A systematic diagnostic approach is necessary to determine the specific aetiology of a patient's hyponatraemia. Therapy must then be dictated not only by recognized reversible causes such as advanced hypothyroidism, adrenal insufficiency, diuretics or other medicines, but also by whether the hyponatraemia occurred acutely or chronically. Information is emerging that the vast majority of cases of hyponatraemia are caused by the nonosmotic release of arginine vasopressin. Now that vasopressin V2-receptor blockers are available, a new era of clinical investigation is necessary to examine whether hyponatraemia is just a marker of severe disease or whether correction of hyponatraemia could improve a patient's quality of life. Such an approach must involve prospective randomized studies in different groups of patients with hyponatraemia, including those with advanced heart failure, those with cirrhosis, patients with cancer, and the elderly.
    Nature Reviews Nephrology 11/2012; 9(1). DOI:10.1038/nrneph.2012.246 · 8.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Risk models to predict 30-day mortality following isolated coronary artery bypass graft is an active area of research. Simple risk predictors are particularly important for cardiothoracic surgeons who are coming under increased scrutiny since these physicians typically care for higher risk patients and thus expect worse outcomes. The objective of this study was to develop a 30-day postoperative mortality risk model for patients undergoing CABG using the American College of Surgeons National Surgical Quality Improvement Program database. Data was extracted and analyzed from the American College of Surgeons National Surgical Quality Improvement Program Participant Use Files (2005-2010). Patients that had ischemic heart disease (ICD9 410-414) undergoing one to four vessel CABG (CPT 33533-33536) were selected. To select for acquired heart disease, only patients age 40 and older were included. Multivariate logistic regression analysis was used to create a risk model. The C-statistic and the Hosmer-Lemeshow goodness-of-fit test were used to evaluate the model. Bootstrap-validated C-statistic was calculated. A total of 2254 cases met selection criteria. Forty-nine patients (2.2%) died within 30 days. Six independent risk factors predictive of short-term mortality were identified including age, preoperative sodium, preoperative blood urea nitrogen, previous percutaneous coronary intervention, dyspnea at rest, and history of prior myocardial infarction. The C-statistic for this model was 0.773 while the bootstrap-validated C-statistic was 0.750. The Hosmer-Lemeshow test had a p-value of 0.675, suggesting the model does not overfit the data. The American College of Surgeons National Surgical Quality Improvement Program risk model has good discrimination for 30-day mortality following coronary artery bypass graft surgery. The model employs six independent variables, making it easy to use in the clinical setting.
    Journal of Cardiothoracic Surgery 04/2015; 10(1):62. DOI:10.1186/s13019-015-0269-y · 1.03 Impact Factor