The impact of red blood cell storage duration on tissue oxygenation in cardiac surgery

Objective

Although storage alters red blood cells, several recent, randomized trials found no differences in clinical outcomes between patients transfused with red blood cells stored for shorter versus longer periods of time. The objective of this study was to see whether storage impairs the in vivo ability of erythrocytes to traverse the microcirculation and deliver oxygen at the tissue level.

B-type natriuretic peptide predicts cardiac morbidity and mortality after major surgery

BACKGROUND: The objective of this study was to determine whether measurement of B-type natriuretic peptide (BNP) concentration before operation could be used to predict perioperative cardiac morbidity. METHODS: A prospective derivation study was performed in high-risk patients undergoing major non-cardiac surgery, with a subsequent validation study. A venous blood sample was taken the day before surgery for measurement of plasma BNP concentration. Screening for cardiac events (non-fatal myocardial infarction and cardiac death) was performed using clinical criteria, cardiac troponin I analysis and serial electrocardiography. RESULTS: Forty-one patients were recruited to the derivation cohort and 149 to the validation cohort. In the derivation cohort, the median (interquartile range) BNP concentration in the 11 patients who had a postoperative cardiac event was 210 (165-380) pg/ml, compared with 34.5 (14-70) pg/ml in those with no cardiac complications (P < 0.001). In the validation cohort, the median BNP concentration in the 15 patients who had a cardiac event was 351 (127-1034) pg/ml, compared with 30.5 (11-79.5) pg/ml in the remainder (P < 0.001). BNP concentration remained a significant outcome predictor in multivariable analysis (P < 0.001). Using receiver-operator curve analysis it was calculated that a BNP concentration of 108.5 pg/ml best predicted the likelihood of cardiac events, with a sensitivity and specificity of 87 per cent each. CONCLUSION: Preoperative serum BNP concentration predicted postoperative cardiac events in patients undergoing major non-cardiac surgery independently of other risk factors.     

Vasoactive-inotropic score and the prediction of morbidity and mortality after cardiac surgery

Background

The vasoactive-inotropic score (VIS) predicts mortality and morbidity after paediatric cardiac surgery. Here we examined whether VIS also predicted outcome in adults after cardiac surgery, and compared predictive capability between VIS and three widely used scoring systems.

Methylene blue reduces mortality and morbidity in vasoplegic patients after cardiac surgery

BACKGROUND: The discovery of nitric oxide as mediator in cardiac postoperative vasoplegia encourages the use of inhibitory drugs such as methylene blue. This drug has been used with favorable results in isolated cases. The purpose of this article is to analyze the incidence of the postoperative vasoplegic syndrome, to consider its prognosis, and to evaluate the effect of intravenous methylene blue on mortality. METHODS: Cardiac surgery patients were consecutively included. Vasoplegic syndrome was defined by the presence of the following five criteria: (1) hypotension, (2) low filling pressures, (3) high or normal cardiac index, (4) low peripheral resistance, and (5) vasopressor requirements. Those with vasoplegia were randomized to receive 1.5 mg/Kg of methylene blue or a placebo. A p value less than 0.05 was considered significant. RESULTS: Six hundred thirty eight cardiac surgery patients were consecutively included in this study. Fifty-six of these patients fulfilled vasoplegia criteria (8.8%) resulting in higher mortality (10.7% or 6 of 56 patients vs 3.6% or 21 of 582 patients; p value = 0.02). Those treated with methylene blue showed morbidity and mortality reductions (0% versus 21.4% or 6 of 28 patients; p value = 0.01). The duration of the vasoplegic syndrome was shorter in those patients treated with the drug, lasting less than 6 hours in all patients. Patients in the control group showed a slower recovery, lasting more than 48 hours in 8 patients (p value = 0.0007). CONCLUSIONS: Vasoplegic postoperative syndrome was seen in 8.8% of all patients. Outcome in patients with vasoplegia was worse with increased morbidity and mortality. The use of methylene blue reduced the high mortality in this population.     

The cardiac anesthesia risk evaluation score: a clinically useful predictor of mortality and morbidity after cardiac surgery

BACKGROUND: The Cardiac Anesthesia Risk Evaluation (CARE) score is a simple risk classification for cardiac surgical patients. It is based on clinical judgment and three clinical variables: comorbid conditions categorized as controlled or uncontrolled, surgical complexity, and urgency of the procedure. This study compared the CARE score with the Parsonnet, Tuman, and Tu multifactorial risk indexes for prediction of mortality and morbidity after cardiac surgery. METHODS: In this prospective study, 3,548 cardiac surgical patients from one institution were risk stratified by two investigators using the CARE score and the three tested multifactorial risk indexes. All patients were also given a CARE score by their attending cardiac anesthesiologist. The first 2,000 patients served as a reference group to determine discrimination of each classification with receiver operating characteristic curves. The following 1,548 patients were used to evaluate calibration using the Pearson chi-square goodness-of-fit test. RESULTS: The areas under the receiver operating characteristic curves for mortality and morbidity were 0.801 and 0.721, respectively, with the CARE score rating by the investigators; 0.786 and 0.710, respectively, with the CARE score rating by the attending anesthesiologists (n = 8); 0.808 and 0.726, respectively, with the Parsonnet index; 0.782 and 0.697, respectively, with the Tuman index; 0.770 and 0.724 with the Tu index, respectively. All risk models had acceptable calibration in predicting mortality and morbidity, except for the Parsonnet classification, which failed calibration for morbidity (P = 0.026). CONCLUSIONS: The CARE score performs as well as multifactorial risk indexes for outcome prediction in cardiac surgery. Cardiac anesthesiologists can integrate this score in their practice and predict patient outcome with acceptable accuracy.     

Cardiac mortality and morbidity after vascular surgery

To determine the clinical, hemodynamic and pathological features that contribute to major cardiac complications after vascular surgery, six patients with early postoperative cardiogenic shock (group 1) were analysed retrospectively and compared to nine patients without complications (group 2) who were carefully analysed prospectively. Four group 1 patients had elective repair of an abdominal aortic aneurysm, one had repair of a false iliac artery aneurysm and one had a femoropopliteal graft inserted. Four group 2 patients had elective repair of an abdominal aortic aneurysm and five had aortobifemoral reconstruction. The Goldman multifactorial index was similar in both groups and indicated an expected death rate of 2% and a morbidity rate of 5%. In group 1, the earliest sign of cardiovascular compromise was an elevated pulmonary wedge pressure during operation. Postoperatively, electrocardiographic evidence of myocardial ischemia was present in all six patients and preceded cardiogenic shock. Autopsy of the four patients who died demonstrated triple-vessel disease in all but recent occlusion in only one patient. There was evidence of extensive subendocardial infarction in all four. Angiography of the two survivors in group 1 also demonstrated triple-vessel disease. The authors conclude that by using ordinary clinical methods it is difficult to identify patients likely to have major complications postoperatively. Elevated pulmonary wedge pressures or electrocardiographic evidence of myocardial ischemia may be early warning signs of impending cardiac catastrophe and should be treated aggressively. The underlying pathophysiology appears to be perioperative stress in a setting of severe triple-vessel coronary artery disease.     

Tranexamic acid reduces blood loss and transfusion in reoperative cardiac surgery

Purpose

The objective of this study was to assess the effect of tranexamic acid (TA), a synthetic antifibrinolytic, on blood loss and the need for transfusion of blood products following repeat cardiac valve surgery.

Methods

After ethics committee approval, 41 patients scheduled for reoperative valve replacement were enrolled in this randomized, double blind, placebo controlled study. Patients were randomized to receive TA (10 g in 500 ml NSaline) or placebo (NSaline) as an iv bolus over 30 min. after anaesthesia induction and prior to skin incision. Intraoperative blood loss was assessed by estimating blood volume on drapes, weighing surgical sponges, and measuring suction bottle returns. Postoperative blood loss was measured from mediastmal chest tube drainage following surgery. Blood products were transfused according to a standardized protocol.

Results

Patient demographics were similar for age, sex, cardiopulmonary bypass pump time, cross clamp time, surgical time, preoperative haemoglobin, coagulation profile, and the number of valves replaced during surgery. Tranexamic acid administration reduced intraoperative blood loss [median (range)] from 1656 (575–6270) to 720 ml (355–5616) (P < 0.01) and postoperative blood loss from I 170 (180–4025) to 538 ml (135–1465) (Intent to Treat n=41, P < 0.01). The total red blood cells transfused (median, range) was reduced from 1500 (0–9300) ml to 480 (0–2850) ml (P < 0.01) in the TA group. In hospital complications and mortality rates were not reduced in the TA group.

Conclusion

Tranexamic acid reduced blood loss and the need for blood product transfusion and appears to be an effective treatment for patients undergoing reoperative cardiac valvular surgery.     

Universal leukocyte reduction of transfused red cells does not provide benefit to patients undergoing cardiac surgery

OBJECTIVE: A policy of universal leukocyte reduction of the blood supply in Finland was implemented at the beginning of 2003. The aim of the present evaluation was to determine the potential role of leukocyte-reduced red blood cells in decreasing postoperative infections. DESIGN: A retrospective cohort study. SETTING: A major university clinic. PARTICIPANTS: Consecutive patients undergoing cardiac surgery during the years 2002 and 2003. INTERVENTIONS: Transfused patients received either buffy-coat-depleted red blood cells before leukocyte reduction (n = 782) or leukocyte-reduced red blood cells after leukocyte reduction (n = 632). MEASUREMENTS AND MAIN RESULTS: The evaluated outcome parameters were culture-proven postoperative infections, 90-day mortality, and length of stay in the intensive care unit. The percentage of patients transfused with red blood cells (56% v 53%, p = 0.16) and amounts of transfused red blood cells (4.3 +/- 6.7 [3.0] units v 4.3 +/- 6.6 [2.0] units, means +/- standard deviation [median], p = 0.48) were comparable between the study groups (buffy-coat-depleted group and leukocyte-reduced group, respectively). The 90-day mortality (6.6% v 6.3%, p = 0.28), the length of intensive care stay (3.6 +/- 4.7 [2.0] days v 4.3 +/- 7.1 [2.0] days, p = 0.34), and the number of patients with culture-proven infections (8.8% v 10.9%, p = 0.19) were unchanged after universal leukocyte reduction. In multivariate comparisons, the leukocyte reduction was not associated with culture-proven postoperative infections and 90-day mortality. CONCLUSION: No beneficial effect of the universal leukocyte reduction in cardiac surgery was found for culture-positive infection rates, 90-day mortality, or length of intensive care stay.     

Is obesity a predictor of mortality,morbidity and readmission after cardiac surgery?

INTRODUCTION: Obesity has been described as a risk factor for the development of coronary artery disease, but it has not been determined whether obesity is associated with adverse outcomes after cardiac surgery. Therefore, we analyzed a large cohort of patients who had undergone cardiac surgery to determine whether obesity is a predictor of mortality, morbidity or early readmission to hospital. METHODS: At the London Health Sciences Centre, an academic tertiary care centre, we prospectively entered data from the cardiac surgical database from July 1999 to April 2002. We collected data on 1310 consecutive, unselected patients who underwent cardiac surgery during that time. We assessed the degree of obesity using the body mass index (BMI), and we prospectively documented the occurrence of 10 major complications after surgery. They included stroke, reoperation for bleeding, life-threatening cardiac arrest or arrhythmia, new renal failure requiring dialysis, septicemia, mediastinitis, sternal dehiscence, respiratory failure, postoperative myocardial infarction and low cardiac output necessitating intra-aortic balloon pump use. Univariable and multivariable analyses were conducted to determine the factors associated with and predictive of postoperative death and major complications. RESULTS: An increased BMI did not increase the risk of early postoperative death. Furthermore, increased BMI was not a predictor of a patient experiencing any of the major complications, except sternal dehiscence. An increased BMI was associated with a higher likelihood of readmission to hospital within 30 days of discharge. CONCLUSION: Obesity was not associated with adverse outcomes after cardiac operations, aside from the increased risks of sternal dehiscence and early hospital readmission.     

Impact of aspirin use on morbidity and mortality in massively transfused cardiac surgery patients: a propensity score matched cohort study

Purpose

Aspirin may prevent organ dysfunction in critically ill patients and mitigate transfusion associated acute lung injury. We hypothesized that aspirin use might be associated with decreased morbidity and mortality in massively transfused cardiac surgery patients.

Methods

A single center retrospective cohort study was performed using data from an 8.5-year period (2006–2014). Massive transfusion was defined as receiving at least 2400 ml (8 units) of red blood cell units intraoperatively. A propensity score model was created to account for the likelihood of receiving aspirin and matched pairs were identified using global optimal matching. The primary endpoint, in-hospital mortality, was compared between aspirin users and non-users. Secondary outcomes including: ICU hours, mechanical lung ventilation hours, prolonged mechanical lung ventilation (>24 h), pneumonia, stroke, acute renal failure, atrial fibrillation, deep sternal wound infection, and multiple organ dysfunction syndrome were also compared.

Results

Of 7492 cardiac surgery patients, 452 (6 %) were massively transfused and mortality was 30.6 %. There were 346 patients included in the matched cohort. No significant association was found between preoperative aspirin use and in-hospital mortality; absolute risk reduction with aspirin = 7.5 % (95 % CI ?2.0 to 16.9 %, p = 0.12). Preoperative aspirin use was associated with fewer total mechanical lung ventilation hours (p = 0.02) and less prolonged mechanical lung ventilation; absolute risk reduction = 11.0 % (95 % CI 1.1–20.5 %, p = 0.02).

Conclusions

Preoperative aspirin use is not associated with decreased in-hospital mortality in massively transfused cardiac surgery patients, but may be associated with less mechanical lung ventilation time.