Adjusting oxygen fraction to avoid hyperoxemia during cardiopulmonary bypass.

Although an adverse influence of hyperoxemia during cardiopulmonary bypass is well documented, there is a wide range of oxygen settings during cardiopulmonary bypass, based mostly on trial and error. The aim of this study was to determine the optimal inspired oxygen fraction during cardiopulmonary bypass. Ninety patients undergoing isolated coronary artery bypass operations were randomly allocated to one of 3 groups of 30 each. In group 1, cardiopulmonary bypass was started with an inspired oxygen fraction of 0.40, increased to 0.60 during rewarming. These settings were 0.40 and 0.50 in group 2, and 0.35 and 0.45 in group 3. Samples for blood gas analysis were collected at defined time periods during the operation. PaO(2) was significantly higher in groups 1 and 2 compared to group 3. All patients in group 1 and 88% of patients in group 2 suffered at least one episode of hyperoxemia during cardiopulmonary bypass, compared to 30% of patients in group 3. The differences were significant, and we concluded that to avoid hyperoxemia, inspired oxygen fraction should be kept at 0.35 during cardiopulmonary bypass and increased to 0.45 during rewarming.

Comparison of antihypertensives after coronary artery surgery.

Hypertension following coronary artery bypass grafting is a common problem that may result in postoperative myocardial infraction or bleeding, Hemodynamic effects were compared in 45 hypertensive coronary bypass patients randomized to receive either diltiazem, nitroglycerin, or sodium nitroprusside. Diltiazem was administered as an intravenous bolus of 0.3 mg.kg-1 within 5 min, followed by infusion of 0.1-0.8 mg.kg-1.h-1 in group 1. Nitroglycerin was infused at a rate of 1-3 microg.kg.h-1 in group 2, and sodium nitroprusside was given at a rate of 1-3 microg.kg-1.min-1 in group 3. Hemodynamic measurements were carried out before infusion (T1) and at 30 min (T2), 2 h (T3), and 12 h (T4) after initiation of treatment in the intensive care unit. Mean arterial pressure decreased significantly in all groups. There were no differences among groups at T1 and T2. At T3, heart rate in group 2 was significantly higher than group 1. At T3 and T4, the double product was highest in group 3 (group 1 vs. 3, p<0.001). These results suggest that the hemodynamic effects of the 3 drugs are similar within the first 30 min. However, after 30 min, diltiazem affords better myocardial performance and more effective control of hypertension.

Fast-track recovery in noncoronary cardiac surgery patients.

OBJECTIVE: Fast-track recovery protocols result in shorter hospital stays and decreased costs in coronary artery bypass grafting (CABG) surgery. However, data based on an objective scoring system are lacking for the impact of these protocols on patients undergoing cardiac surgery other than isolated CABG. METHODS: Between March 1999 and March 2003, 299 consecutive patients who underwent open cardiac surgery other than isolated CABG were analyzed to evaluate the safety and efficacy of fast-track recovery. The parameters evaluated as predictors of mortality, ie, delayed extubation (>360 minutes), intensive care unit (ICU) discharge (>24 hours), increased length of hospital stay (>5 days), and red blood cell transfusion, were determined by regression analysis. Standard perioperative data were collected prospectively for every patient. RESULTS: Seventy-two percent of the patients were extubated within 6 hours, 87% were discharged from the ICU within 24 hours, and 60% were discharged from the hospital within 5 days. No red blood cells were transfused in 67% of the patients. There were no predictors of mortality. The predictors of delayed extubation were preoperative congestive heart failure (P = .005; odds ratio [OR], 4.5; 95% confidence interval [CI], 1.6-12.6) and peripheral vascular disease (P = .02; OR, 6; 95% CI, 1.9-19.4). Factors leading to increased ICU stay were diabetes (P = .05; OR, 3.6; 95% CI, 1-12.6), emergent operation (P = .04; OR, 6.1; 95% CI, 1.1-33.2), red blood cell transfusion (P = .03; OR, 2.9; 95% CI, 1.1-7.8), chest tube drainage >1000 mL (P = .03; OR, 3.4; 95% CI, 1.1-10.2). The predictors of increased length of hospital stay were ICU stay >24 hours (P = .001; OR, 5.9; 95% CI, 2-17), EuroSCORE >5 (P = .05; OR, 1.8; 95% CI, 1-3.2), and chronic obstructive pulmonary disease (P = .003; OR, 3.7; 95% CI, 1.5-8.7). Predictive factors for transfusion of red blood cells were diabetes (P = .04; OR, 2.9; 95% CI, 1.1-8.1), delayed extubation (P = .02; OR, 2.7; 95% CI, 1.4-5.1), increased ICU stay (P = .04; OR, 2.6; 95% CI, 1-6.4), and chest tube drainage >1000 mL (P = .001; OR, 4.3; 95% CI, 2-9.3). CONCLUSIONS: This study confirms the safety and efficacy of the fast-track recovery protocol in patients undergoing open cardiac surgery other than isolated CABG.

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.

Clopidogrel does not increase bleeding and allogenic blood transfusion in coronary artery surgery.

OBJECTIVES: Platelet dysfunction is one of the major reasons of postoperative bleeding following coronary artery surgery. The aim of this study was to evaluate the effects of clopidogrel; a specific and potent irreversible inhibitor of platelet aggregation; on bleeding and use of blood and blood products after coronary artery bypass surgery (CABG). METHODS: Preoperative patient characteristics and perioperative and postoperative data were collected prospectively in 1628 consecutive patients undergoing isolated CABG performed by the same surgical and anesthesia team. Of these, 48 were receiving clopidogrel preoperatively. Of the 1628 patients, 1456 underwent elective and 172 (10.6%) underwent non-elective operation. Thirty-six (2.5%) of the elective patients and 12 (7%) of the non-elective patients were using clopidogrel, preoperatively. Baseline characteristics, chest tube output, and the need for reexploration or for blood and blood product transfusion of clopidogrel recipients and non-recipients were compared. The clopidogrel group had higher prothrombin time level (12.6+/-1.6; 11.5+/-1.7 s, (P=0.013), however comparable aPTT level (32.6+/-4.5 vs. 31.4+/-4.5 s), and platelet count (275,000+/-98,000 vs. 280,000+/-72,000 dl(-1)). RESULTS: The need for reexploration or for blood and blood product transfusion, chest tube output, ICU length of stay (20.1+/-2.9 vs. 21.9+/-13.5 h; P=NS), and hospital length of stay (5.5+/-1.7 vs. 5.4+/-2.1 days; P=NS) were similar in clopidogrel recipients and non-recipients, respectively. Further analysis demonstrated no significant difference in use of homologous blood or fresh frozen plasma, amount of postoperative bleeding and reoperation rates for bleeding as well as length of intensive care unit and hospital stay between the clopidogrel and the control groups both in elective and non-elective patients. CONCLUSIONS: The results of this study suggest that preoperative use of clopidogrel is not associated with increased bleeding and need for surgical exploration as well as risk of blood and blood product transfusion after CABG.