Improving cardiopulmonary bypass: does continuous blood gas monitoring have a role to play?

The CDI 500 (Terumo Cardiovascular Systems, Ann Arbor, MI) is an in-line blood gas monitoring device that has been used in clinical practice for over a decade. Few randomized studies have evaluated the value of this device with respect to improved perfusion management. We routinely use automated continuous quality indicator programs to assess perfusion management. The aim of this study is to investigate in a prospective randomized trial the role of in-line blood gas monitoring in the improvement of blood gas management during cardiopulmonary bypass (CPB) utilizing continuous quality indicators. Patients were randomized into two groups (Control, CDI). Patients in the Control group received our standard CPB blood gas management, with intermittent blood gas results. Continuous blood gas measurements from the CDI 500 were recorded at 20-second intervals, with the perfusionist blinded to these measurements. Patients in the CDI group received standard CPB blood gas management, in addition to continuous blood gas measurements visible on the CDI 500, the alarm system activated, and the data recorded. Perfusion management for all cases was guided by institutional protocols. One hundred patients (50 in each group) were included in the study. No significant difference existed between the groups on demographic, surgical, or clinical outcomes. Blood gas levels of patients in the CDI group were able to be maintained in accordance to protocol a greater percentage of the time, e.g., pCO2 management was 2% versus 20% (p = .008); this was most notable for differences between the Control and the CDI group for pCO2 > 45 mmHg (p = .003). Practice variation determined via statistical control charts improved for both pH and pCO2, represented by a decrease in the variation associated with practice. Continuous blood gas monitoring with the CDI 500 results in significantly improved blood gas management as determined by adherence to institutional protocols.

Surgical challenges in rheumatic heart disease in the Australian indigenous population.

BACKGROUND: Acute rheumatic fever, leading to rheumatic heart disease (RHD), is rare in Australia except amongst Aboriginal and Torres Strait Islander people. METHODS: Cardiac surgical procedures performed at Flinders Medical Centre on patients from the Top End of the Northern Territory from 1993 to 2008 were reviewed. This study compared Indigenous and non-Indigenous patients on short term morbidity and long term survival employing logistic regression and Cox proportional hazard models. We also outline the challenges of managing Aboriginal patients, as our unit services vast areas of northern Australia inhabited by Indigenous people. RESULTS: The total number of patients from the Northern Territory was 835. Amongst the Indigenous patients, there were 235 (55.6%) isolated coronary artery bypass graft procedures, 171 (40.4%) patients underwent isolated valvular surgery (91 mitral and 80 aortic), and 17 (4.0%) underwent combined valvular surgery with coronary artery bypass graft surgery. CONCLUSIONS: Aboriginal patients requiring valve surgery are younger and have greater comorbidity than non-Aboriginal people. Short term surgical results are similar to non-Aboriginal people but long term outcomes appear to be inferior. Age and socioeconomic conditions of Indigenous patients need to be considered. Cultural issues should be understood and acknowledged and surgery better focused around surgical units with appropriate infrastructure.

Negative emotions and quality of life six months after cardiac surgery: the dominant role of depression not anxiety symptoms.

The specific syndromal aspects of depression and anxiety have not been explored in relation to changes in health related quality of life (HRQOL) after cardiac surgery. The purpose of this study was to examine the impact of general stress, depression and anxiety on HRQOL after coronary artery bypass graft (CABG) surgery. Utilizing a tripartite conceptual model of depression and anxiety, it was hypothesized that general stress symptoms, rather than unique depressive or anxiogenic symptoms, would be associated with lower HRQOL 6 months after CABG surgery. Elective CABG patients (n=226) completed baseline and postoperative self-report measures of negative emotions and HRQOL, and 193 patients completed these measures at 6-month follow-up. Multiple linear regression analyses and logit link analyses were performed to test the hypothesis. Elevated depression symptoms before and after surgery showed an association with lower and worse HRQOL for vitality and social role functioning and physical and general health. This study adds to previous research by outlining discrete associations between specific HRQOL domains, and is perhaps the first to test a theoretical model of depression and anxiety in relation to cardiac CABG patients' perceptions of HRQOL. These findings encourage further research on negative emotions and HRQOL in cardiac surgery patients and the practical implications of these findings are discussed.

Anxiety and depression as risk factors for mortality after coronary artery bypass surgery.

OBJECTIVE: This retrospective study examined the association between symptoms of depression, anxiety, and mortality risk following coronary artery bypass graft (CABG) surgery. METHODS: We assessed 440 CABG surgery patients' scores on the Depression Anxiety and Stress Scale (DASS) and followed up mortality status for a median of 5 years, 10 months. RESULTS: There were 67 (15%) deaths overall during the follow-up period. Adjusted survival analysis showed that preoperative depressive symptoms were not associated with a significantly higher risk of mortality. Survival analysis with preoperative anxiety adjusted for covariates showed a significantly increased mortality risk [hazard ratio (HR)=1.88 (95% CI=1.12-3.17), P=.02]. CONCLUSION: Preoperative anxiety symptoms were significantly associated with increased mortality risk after adjustment for known mortality risk factors. Future research should further explore the simultaneous role of anxiety and depression on mortality following CABG.

Neuropsychologic and quality-of-life outcomes after coronary artery bypass surgery with and without cardiopulmonary bypass: a prospective randomized trial.

OBJECTIVES: The objective of this study was to compare neuropsychologic and quality-of-life outcomes of patients undergoing off-pump coronary artery bypass surgery to those undergoing coronary artery bypass graft surgery using conventional cardiopulmonary bypass. DESIGN: A prospective randomized trial of coronary artery bypass graft surgery with and without the use of cardiopulmonary bypass. SETTING: A cardiothoracic surgery unit at a tertiary hospital. PARTICIPANTS: Sixty-six patients undergoing coronary artery bypass graft surgery and a control group of 50 participants not undergoing cardiac surgery. INTERVENTIONS: Patients were randomized to receive coronary artery bypass graft surgery with cardiopulmonary bypass or randomized to coronary artery bypass graft surgery without the use of cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: The proportions of neuropsychologic deficits and improvement in quality-of-life were comparable regardless of whether patients were randomized to receive off-pump coronary artery bypass graft surgery or conventional coronary artery graft surgery with cardiopulmonary bypass. CONCLUSIONS: Patients receiving coronary artery bypass grafts without cardiopulmonary bypass did not show fewer cognitive deficits or greater improvement in quality of life.

Assessment of myocardial injury by troponin T in off-pump coronary artery grafting and conventional coronary artery graft surgery.

PURPOSE: The present study was undertaken to assess the degree of myocardial injury, using troponin T (TnT), in off-pump coronary artery surgery (OPCAB) and in a comparable patient group undergoing conventional coronary artery graft surgery (CABG). METHODS: Twenty-seven OPCAB and 27 CABG patients were investigated. Blood samples for TnT were taken at intubation and at 12, 24 and 72 h. Nine patients (five OPCAB, four CABG) underwent 2 h sampling for 12 h for the assessment of the TnT release profile. All patients had an electrocardiogram performed preoperatively and on the mornings of days 1 and 5 postoperatively. RESULTS: The OPCAB group had significantly greater Canadian Heart Classification 3 patients (P = 0.003); however, other demographic data were similar between the two groups. All patients had normal TnT at initial sampling. The mean number of grafts in each group was 1.8 +/- 0.6 for OPCAB and 1.9 +/- 0.3 for CABG (P = NS). There were two new Q wave myocardial infarctions in the CABG group and none in the OPCAB group. These cases were excluded from biochemical analyses. Troponin T release was significantly less in the OPCAB group at 12 and 24 h (P < 0.001 and P = 0.03, respectively). Peak TnT release occurred at 6-8 h in both groups. Troponin T release was significantly lower in the OPCAB group at 2, 4, 6, 8, 10 and 12 h (P = 0.01, P = 0.03, P = 0.02, P = 0.02, P = 0.03 and P = 0.04, respectively). Postoperatively, the OPCAB group required less blood transfusion (P = 0.02). CONCLUSIONS: The OPCAB group demonstrated a significantly reduced TnT release profile compared with the CABG group.

Relationship between elevated preoperative troponin T and adverse outcomes following cardiac surgery.

BACKGROUND: The prognostic value of troponin T (TnT) has been demonstrated in patients following a myocardial infarction. There are limited data regarding the prognostic utility of preoperative TnT in patients undergoing cardiac surgery. The aim of the present study was to determine if elevated preoperative TnT is a predictor of more complex recovery outcomes in the cardiac surgical setting. METHODS: A single preoperative TnT measurement was assessed in 696 patients undergoing isolated coronary artery bypass graft surgery. Elevated preoperative TnT levels were classified as > or =0.2 ng/mL. Preoperative, intraoperative, intensive care and postoperative events were prospectively recorded for all patients, and retrospectively reviewed for the present study. RESULTS: Elevated preoperative TnT levels were detected in 10% (71/696) of patients. Compared to patients with normal TnT levels, elevated preoperative TnT increased the risk of mortality at 30 days (7% vs 1%, P = 0.004, odds ratio (OR) = 6.7) and 2 years (14% vs 3%, P < 0.001, OR = 5.0), and resulted in prolonged intensive care unit (ICU) stays (P < 0.001) and longer postoperative hospitalization (P < 0.001). Elevated preoperative TnT was also associated with an increased need for perioperative and postoperative cardiovascular support, early ischaemic change and postoperative congestive cardiac failure. In multivariate analyses preoperative TnT was a significant independent predictor of 30-day and 2-year mortality, and duration of ICU stay. CONCLUSIONS: Elevated preoperative TnT highlights a subgroup of cardiac surgical patients who are more likely to have a post-operative course with increased morbidity and mortality.

Aortic valve prosthesis-patient mismatch and long-term outcomes: 19-year single-center experience.

BACKGROUND: The clinical effects of prosthesis-patient mismatch (PPM) after aortic valve replacement, with respect to morbidity and survival, remain controversial, particularly in high-risk patient subgroups. METHODS: Patients undergoing aortic valve replacement from January 1992 to December 2010 were classified according to effective orifice area index into severe PPM (effective orifice area index<0.65 cm²/m²), moderate PPM (effective orifice area index 0.65 to 0.85 cm²/m²), and absent PPM (effective orifice area index>0.85 cm²/m²). Analyses examined major morbidity and total all-cause death. RESULTS: Prosthesis-patient mismatch was classified as severe (92 of 1,060; 8.7%), moderate (440 of 1,060; 41.5%), or absent (528 of 1,060; 49.8%). Moderate and severe PPM were unrelated to in-hospital morbidity or mortality. There were 440 deaths (41.5%) at 5.6 years median follow-up (interquartile range, 2.9 to 9.1). Trend toward poorer survival according to PPM group (χ2=5.46; p=0.07) was attenuated further with covariate adjustment. Sensitivity analyses demonstrated discrete mortality effects for moderate PPM in association with concomitant coronary artery bypass grafting, impaired left ventricular function, and older age (significant hazard ratios range, 1.05 to 1.57). Severe PPM also increased mortality risk in association with older age, concomitant coronary artery bypass grafting, and New York Heart Association Class III or IV (significant hazard ratios range, 1.06 to 2.65). CONCLUSIONS: Prosthesis-patient mismatch was not associated with mortality in covariate-adjusted models. However, a discrete mortality risk was attributable to moderate and severe PPM in patients of older age, or those with left ventricular dysfunction, New York Heart Association class III or IV, and concomitant coronary artery bypass grafting.

Female sex as an independent predictor of morbidity and survival after isolated coronary artery bypass grafting.

BACKGROUND: This study sought to determine whether female sex was an independent risk factor for combined in-hospital morbidity, mortality, and long-term survival after coronary artery bypass grafting (CABG). METHODS: Data were collected prospectively for 1,114 (23.5%) women and 3,628 (76.5%) men operated on between January 1, 1996 and December 31, 2004 with median follow-up of 7.9 years (interquartile range 3.55 to 10.5). The combined morbidity end point was defined as in-hospital renal failure, stroke, ventilation for more than 24 hours, deep sternal wound infection, reoperation, myocardial infarction (MI), and mortality less than 30 days after discharge. The long-term all-cause and cardiac mortality outcomes were analyzed using multivariate proportional hazard regression. RESULTS: Females were older, with lower body surface area, and generally had more significant comorbid conditions than did males (p<0.05). Female sex was associated with increased odds of the combined morbidity end point (adjusted odds ratio [OR]=1.29; 95% confidence interval, 1.04 to 1.59, p=0.02). There were 868 deaths (18.3% of total sample) during the follow-up period, and 305 deaths (n=305 [35.1%] of deaths) were deemed to be of cardiac causes. In adjusted survival models, female sex was associated with cardiac mortality (hazard ratio [HR]=1.28; 95% confidence interval, 0.96 to 1.73; p=0.10) but not with all-cause mortality (HR=0.92; 95% confidence interval, 0.77 to 1.11; p=0.38). CONCLUSIONS: Female sex was associated with early combined morbidity and long-term cardiac mortality but not long-term all-cause mortality. A greater proportion of concomitant risk factors characterize female patients undergoing CABG.

Preoperative and intraoperative factors associated with long-term survival in octogenarian cardiac surgery patients.

BACKGROUND: The proportion of octogenarians undergoing cardiac surgery is increasing though few studies have examined the simultaneous impact of preoperative and intraoperative factors on long-term survival in this age group. This study aimed to describe the preoperative clinical and demographic characteristics associated with long-term mortality risk and determine whether intraoperative factors related to surgical and cardiopulmonary bypass techniques impacted upon these. METHODS: Octogenarians undergoing coronary artery bypass grafting (CABG) +/- concomitant valvular procedure between 1992 and 2005 from three institutions were included in this study. The survival data of 606 octogenarians (414 isolated CABG, 192 concomitant valve procedures) were analyzed with multivariable proportional hazard models. RESULTS: There were 271 deaths and 2,675 person years of survival for analysis, and median follow-up was 7.15 years (95% confidence interval 6.47 to 7.82 years). Five-year survival for isolated CABG and concomitant valve procedures was 66.5% and 61.5%, respectively. An increase in mortality risk was attributable to older age, hypercholesterolemia, severely impaired left ventricular function, tobacco smoking history and high creatinine (> or = 0.15 mmol/L). Time spent on cardiopulmonary bypass was the only intraoperative risk factor associated with an increase in mortality risk (hazard ratio 1.01, 95% confidence interval: 1.00 to 1.02; p < 0.001). CONCLUSIONS: This study showed that from the intraoperative parameters examined only time spent on cardiopulmonary bypass was associated with long-term survival. Surgeons may be assisted in patient selection by identifying the factors that influence long-term survival among octogenarians and development of a preoperative risk model specific for this age group.

Survival after isolated coronary artery bypass grafting in patients with severe left ventricular dysfunction.

BACKGROUND: The number of patients with severe left ventricular dysfunction referred for coronary artery bypass graft surgery (CABG) continues to increase. The aim of this study was to document the long-term survival in this group. METHODS: The 30-day mortality and long-term survival outcome of 162 patients with severely depressed left ventricular ejection fraction (LVEF [< or = 30%]) who had consecutive isolated CABG between 1996 and 2005 were compared with 661 patients who had impaired LVEF (31% to 59%) and 1,231 patients with normal LVEF (> or = 60%). RESULTS: The 30-day mortality for patients with severely depressed LVEF was 5.6%. The median survival for deceased patients was 3.4 years (interquartile range, 1.3 to 5.9). The risk of all-cause mortality attributable to severe left ventricular dysfunction was increased twofold compared with having normal LVEF (hazard ratio = 2.28; 95% confidence interval: 1.64 to 3.18; p < 0.001). Among the covariates, older age, emergency surgery, mitral incompetence, smoking history, respiratory disease, diabetes mellitus, cerebrovascular disease, intensive care unit intubation for 24 hours or more, postoperative renal failure, postoperative pleural effusion, and nonuse of left internal mammary artery were detected as significant predictors of increased mortality risk. CONCLUSIONS: The mortality rate among CABG patients with severely depressed LVEF was comparable to that reported in other series. Severe left ventricular dysfunction carried more than a twofold increased mortality risk compared with patients who had an impaired LVEF, adjusted for traditional risk factors. These data suggest that LVEF has an impact on long-term patient survival even after preoperative covariates and postoperative morbidity outcomes are considered.

Outcomes of cardiac surgery in Indigenous Australians.

OBJECTIVE: To describe baseline characteristics, operative events and late mortality among Indigenous Australians undergoing cardiac surgery. DESIGN, SETTING AND PARTICIPANTS: Prospective study of consecutive patients undergoing cardiac surgery at Flinders Medical Centre in Adelaide between January 2000 and December 2005. MAIN OUTCOME MEASURES: Operative (30-day) mortality and late mortality after cardiac surgery. RESULTS: Of 2635 patients undergoing cardiac surgery, 283 (10.7%) were Indigenous. Indigenous patients were substantially younger than non-Indigenous patients (mean, 47 [SD, 14] years v 65 [SD, 12] years; P = 0.001) and were more likely to have diabetes (39.6% v 27.3%; P = 0.001), renal dysfunction (3.2% v 1.2%; P = 0.009), and valvular surgery (53.0% v 23.1%; P < 0.001). There was a non-significant trend toward excess operative mortality in Indigenous patients (Indigenous 2.5% v non-Indigenous 1.3%; hazard ratio [HR], 1.67 [95% CI, 0.74-3.75]). But in the under-55-years age cohort, the difference between the two groups was highly significant (Indigenous 3.3% v non-Indigenous 0.4%; HR, 7.99 [95% CI, 1.66-38.50]), even after adjustment for euroSCORE (the European System for Cardiac Operative Risk Evaluation). Survival at 1 and 5 years was 94.0% and 80.6%, respectively, for Indigenous patients compared with 96.7% and 87.7%, respectively, for non-Indigenous patients. There was an excess in euroSCORE-adjusted mortality in the Indigenous cohort overall (HR, 1.46 [95% CI, 1.03-2.07]) that strengthened when restricted to the under-55-years cohort (HR, 6.9 [95% CI, 1.42-33.5]). CONCLUSION: Indigenous Australians present for cardiac surgery nearly 20 years earlier than non-Indigenous Australians and experience excess age-stratified operative and late mortality.

Neuropsychological function 5 years after cardiac surgery and the effect of psychological distress.

Research has shown conflicting results with regard to the influence of depression and anxiety on neuropsychological performance following coronary artery bypass graft (CABG) surgery. Notably, the independent effects of depression and anxiety have not been examined among CABG candidates in the longer term where it is has been suggested that these patients show marked cognitive deterioration. A neuropsychological test battery and measures of psychological distress were completed by 86 CABG patients and 50 nonsurgical control participants at baseline and 6 months, whereas 75 patients and 36 controls, respectively, completed a 5-year follow-up. In CABG patients, cognitive and affective depressive symptoms were independently associated with lower and worse performance on the Boston Naming Test, Purdue Peg Board, and Digit Symbol Coding 6 months after surgery, whereas at 5-year follow-up an effect for Digit Symbol persisted, and an association was also observed for the Trail Making Test (TMT). On average, CABG patients performed worse on TMT and Digit Symbol at 6 months, whereas at 5-year follow-up their performance was worse on short-term delayed verbal recall. The results among the CABG patients did not show a consistent pattern of association between psychological distress and those neuropsychological domains that were on average significantly lower than a nonsurgical control group. The results here also support the use of nonbiased statistical methodology to document dysfunction among heterogeneous cognitive domains after CABG surgery.

Stroke after coronary artery bypass grafting.

BACKGROUND: Despite the continuing improvements in surgical and cardiopulmonary bypass techniques during cardiac surgery, stroke remains a devastating complication. This study aimed to identify the preoperative and intraoperative risk factors for developing a perioperative stroke in patients undergoing coronary artery bypass graft surgery on cardiopulmonary bypass. METHODS: A total of 4,380 consecutive patients who received isolated coronary artery grafting on cardiopulmonary bypass between 1992 and 2002 were included. The sample contained three cardiopulmonary bypass temperature strategies: hypothermic (< 31 degrees C, n = 1,853), tepid (32-35 degrees C, n = 1,088), and normothermic (> 36 degrees C, n = 1,439). Outcome measures reported include stroke incidence, 30-day mortality, and hospital length of stay. RESULTS: The incidence of stroke was 1.2% (n = 51). Stroke patients were older, were more likely to be diabetic, hypertensive, have creatinine levels greater than 0.12 mmol/L, and have a history of stroke than those who did not have stroke (p < 0.05). Multivariate logistic regressions identified diabetes (p = 0.01), history of stroke (p = 0.04), and older age (p = 0.05) as independent predictors of stroke for all patients. The 30-day mortality for stroke patients was ten times greater than that of those who did not suffer stroke (17.6 vs 1.7%). CONCLUSIONS: Diabetes, history of stroke, and older age were identified as risk factors for stroke after coronary bypass; the temperature at which cardiopulmonary bypass was performed was not significant.

Clopidogrel and bleeding after coronary artery bypass graft surgery.

BACKGROUND: There is evidence that clopidogrel (with or without aspirin) confers superior outcomes in patients with coronary artery disease. The purpose of this study is to review the effect of preoperative clopidogrel administration on clinical outcome, bleeding complications and resource utilization after coronary artery bypass graft surgery. METHODS: Patient data were prospectively collected from 919 patients who had isolated coronary surgery during the period 2000 to 2003. Outcome comparisons were studied, firstly between patients who received preoperative clopidogrel with those who did not, and secondly between patients on clopidogrel only, aspirin only, both or neither medications. RESULTS: Twenty-four patients (2.6%) were on clopidogrel only, 598 (65.1%) were on aspirin only, 61 (6.6%) were on both, and 236 (25.7%) were on neither. Clopidogrel (n = 85) versus no clopidogrel (n = 834): there were no significant differences in the off-pump patients. In the on-pump patients, the clopidogrel group had significantly increased bleeding (p = 0.02), blood transfused (p = 0.01), intensive care (p = 0.03), and hospital stays (p = 0.03). There were no significant differences in surgical reexploration, perioperative myocardial infarction, intraoperative balloon pump use, inotropic support or 30-day mortality. Clopidogrel versus aspirin versus both versus neither: patients on both clopidogrel and aspirin had significantly more postoperative bleeding than patients on aspirin alone or on neither medication. CONCLUSIONS: The preoperative use of clopidogrel in patients undergoing coronary artery bypass graft surgery showed limited clinical benefits; however, its use significantly increased the risk of bleeding, blood transfusion, and resource utilization.