Clinical Characteristics of Preoperative Hypoalbuminemia Predict Outcome of Cardiovascular Surgery

Abstract

Objective: To define the clinical characteristics and outcome of preoperative hypoalbuminemia in adult cardiovascular surgery. Study: Inception cohort. Setting: Adult cardiovascular intensive care unit (CVICU). Patients: Admissions to CVICU between January 1 and December 31, 1993. Intervention: Preoperative hypoalbuminemia (serum albumin ≤3.5 g/dL) was classified by the presence of malnutrition cachexia (body mass index of ≤20 kg/m²), liver insufficiency (serum bilirubin ≥2.0 mg/dL), history of congestive heart failure, or hypoalbuminemia alone. Demographics, chronic diseases, systemic hemodynamics, and laboratory data were obtained at preoperative and later on admission and during the stay in the CVICU. Outcome measures: Postoperative organ dysfunction, nosocomial infections, length of mechanical ventilation, hospitalization and death. Results: A total of 2,743 patients (91%) of 3,025 patients who were admitted to the CVICU were enrolled in the study. Preoperative hypoalbuminemia was found in 325 patients (12%): hypoalbuminemia and cachexia in 21 patients (6%), hypoalbuminemia and liver insufficiency in 26 patients (8%), hypoalbuminemia and history of congestive heart failure in 102 patients (31%), and hypoalbuminemia alone in 176 patients (54%). Clinical features of preoperative hypoalbuminemia were age ≥75 years, female gender, left ventricular ejection fraction ≤35%, hematocrit ≤34%, serum creatinine ≥1.9 mg/dL, systemic oxygen delivery ≤350 mL/min · m², acute stressful conditions (eg, infective endocarditis, acute myocardial infarction, or emergency surgery) and chronic obstructive pulmonary airway disease. Redo operations, combined valve and coronary artery bypass graft, mitral valve replacement, and thoracic aortic surgery were the commonest types of surgery performed in these patients. All types of hypoalbuminemia except for malnutrition cachexia increased the likelihood of postoperative organ dysfunction (cardiac, pulmonary, renal, hepatic, and neurologic), gastrointestinal bleeding, nosocomial infections, length of mechanical ventilation, stay in the CVICU, and hospital death. Cachectic hypoalbuminemia increased the requirement for postoperative parenteral nutrition and prolonged the length of stay in hospital. Conclusion: Preoperative hypoalbuminemia was attributed to malnutrition cachexia, liver insufficiency or congestive heart failure in <50% of cardiac patients undergoing cardiovascular surgery. All types of hypoalbuminemia except for malnutrition cachexia increased the likelihood of postoperative organ dysfunction, nosocomial infections, prolonged mechanical ventilation, and death. The morbidity and mortality attributed to hypoalbuminemia could be explained by the underlying clinical characteristics rather than malnutrition cachexia in cardiac patients. (journal of Parenteral and Enteral Nutrition 21:81-90, 1997)