Lactic acidosis after cardiac surgery is associated with adverse outcome.

BACKGROUND: The accurate identification of patients who have the potential to further deteriorate after cardiac surgery is difficult. Elevated serum lactate level after cardiac surgery is an indicator of systemic hypoperfusion and tissue hypoxia. The aim of this study was to investigate the effect of increased serum lactate on outcome after on-pump coronary artery bypass grafting. METHODS: Serum lactate level was measured in 776 patients within half an hour after surgery. Lactate level was less than or equal to 2 mmol/L in 534 patients (low lactate group) and more than 2 mmol/L in 242 patients (high lactate group). Continuous variables were analyzed with the Student t test. The chi 2 test and Fisher exact test were used to compare categorical variables. RESULTS: Demographic characteristics and details of surgery were similar in both groups. Increased cross-clamp and cardiopulmonary bypass times and highly positive fluid balance at the end of surgery were associated with a significant rise in postoperative lactate levels, which leads to increased need for intraaortic balloon pump support (odds ration [OR], 5.9, P =.006), increased likelihood of >24 h intensive care unit stay (OR, 3.4, P =.0001), greater need for red blood cell transfusion (OR, 1.6, P =.002), increased length of hospital stay, and higher mortality rates (OR, 5.6, P =.04). CONCLUSIONS: This study has demonstrated that elevated blood lactate level is associated with adverse outcome, and monitoring the blood lactate level during and after cardiac surgery is a valuable tool in identifying the patients who have the potential to deteriorate.

Highly positive intraoperative fluid balance during cardiac surgery is associated with adverse outcome.

UNLABELLED: Hemodilution and increase in capillary permeability occurring with cardiopulmonary bypass (CPB) impose a risk for tissue edema and blood transfusion that may result in an increased complication rate after coronary artery bypass grafting (CABG). Of the 1280 consecutive patients undergoing isolated on-pump CABG, total fluid balance at the end of the operation was less than or equal to 500 mL in 1155 (Group 1) and more than 500 mL in 125 (Group 2). During CPB, blood was added to the reservoir only when the hematocrit fell to 17% or less and crystalloid solution only when the pump flow index fell below 2.0 L/min/m2. Anesthetic, surgical, and postoperative management and diagnoses were the same in all patients, and a single surgical and anesthesia team performed all operations. No patient was excluded from the study. RESULTS: Hypertension, diabetes, chronic obstructive pulmonary disease, New York Heart Association (NYHA) Class III-IV, use of angiotensin converting enzyme (ACE) inhibitors, chronic renal failure, and female gender were the significant preoperative risk factors for increased volume replacement during CPB. The groups were similar in body mass index, preoperative hematocrit values, total fluid balance in the intensive care unit (ICU), and total chest tube output. However, red blood cells' transfusion rate, readmission rate to the ICU and length of hospital stay were significantly higher in Group 2 patients. Multiple logistic regression revealed that age > 70 years (p < 0.001, Odds Ratio (OR): 2, 95% CI: 1.4-2.8), and total fluid balance > 500 mL at the end of the operation (p < 0.01, OR: 2.2, 95% CI: 1.5-3.2) were the predictors of increased length of stay. For transfusion of red blood cells, age > 70 years (p < 0.0001, OR: 2.3, 95% CI: 1.6-3.3), and total fluid balance > 500 mL at the end of the operation (p < 0.001, OR: 2, 95% CI: 1.3-2.9) were the only significant risk factors. This study suggests that intraoperative volume overload increases blood transfusion and length of hospital stay in patients undergoing CABG.

Coronary artery bypass surgery in patients with severe left ventricular dysfunction.

OBJECTIVE: The role of coronary artery bypass grafting (CABG) in patients with severe left ventricular dysfunction was evaluated. METHODS: Two hundred and twelve patients (152 men, 60 women; age 35 to 82, mean 55) with ejection fraction (EF) of less than 30% underwent CABG between January 1996 and February 2001 by a single surgeon (SA). They compromised of 12% of 1759 patients operated on in this period. EF ranged from 17% to 30% (mean 25%). Preoperatively 68% had congestive heart failure and 72% had severe angina (CCS 3 or 4). A left main lesion was found in 26% of the cases. The mean number of grafts was 3.18 per patient. The left internal mammary artery (LIMA) was used on 107 patients (50.4%). Preoperative intraaortic balloon pump (IABP) was used on 32 patients (15%). Endarterectomy was performed on 53 patients (25%). The patients were followed for up to 58 months (mean 28.7). RESULTS: Twelve patients died in hospital (5.6%). Survival was 94%, 87%, 80% and 73% at 1, 2, 3 and 4 years respectively. Among the preoperative variables survival was negatively affected by chronic renal failure, older age, congestive heart failure, elevated pulmonary artery pressure and recent myocardial infarction, by means of multivariate analysis. Preoperative IABP support improved the operative mortality significantly (P=0.002). Use of LIMA did not have any influence on survival. CONCLUSION: CABG on patients with poor left ventricular function: (1). Can be performed with an acceptable mortality. (2). Mid term results are encouraging. (3). Preoperative IABP support improves the chance of survival.