Diabetes mellitus and morbidity and mortality risks after coronary artery bypass surgery

Sitagliptin for the prevention of stress hyperglycemia in patients without diabetes undergoing coronary artery bypass graft (CABG) surgery

AIMS

To determine if treatment with sitagliptin, a dipeptidyl peptidase-4 inhibitor, can prevent stress hyperglycemia in patients without diabetes undergoing coronary artery bypass graft (CABG) surgery.

METHODS

We conducted a pilot, double-blinded, placebo-controlled randomized trial in adults (18-80 years) without history of diabetes. Participants received sitagliptin or placebo once daily, starting the day prior to surgery and continued for up to 10 days. Primary outcome was differences in the frequency of stress hyperglycemia (blood glucose (BG) >180 mg/dL) after surgery among groups.

RESULTS

We randomized 32 participants to receive sitagliptin and 28 to placebo (mean age 64±10 years and HbA1c: 5.6%±0.5%). Treatment with sitagliptin resulted in lower BG levels prior to surgery (101±mg/dL vs 107±13 mg/dL, p=0.01); however, there were no differences in the mean BG concentration, proportion of patients who developed stress hyperglycemia (21% vs 22%, p>0.99), length of hospital stay, rate of perioperative complications and need for insulin therapy in the intensive care unit or during the hospital stay.

CONCLUSION

The use of sitagliptin during the perioperative period did not prevent the development of stress hyperglycemia or need for insulin therapy in patients without diabetes undergoing CABG surgery.

Sitagliptin for prevention of stress hyperglycemia in patients without diabetes undergoing general surgery: A pilot randomized study

AIM

We investigated if a dipeptidyl peptidase-4 inhibitor, sitagliptin, can prevent perioperative stress hyperglycemia in patients without prior history of diabetes mellitus undergoing general surgery.

METHODS

This double-blind pilot trial randomized general surgery patients to receive sitagliptin (n = 44) or placebo (n = 36) once daily, starting one day prior to surgery and continued during the hospital stay. The primary outcome was occurrence of stress hyperglycemia, defined by blood glucose (BG) >140 mg/dL and >180 mg/dL after surgery. Secondary outcomes included: length-of-stay, ICU transfers, hypoglycemia, and hospital complications.

RESULTS

BG >140 mg/dL was present in 44 (55%) of subjects following surgery. There were no differences in hyperglycemia between placebo and sitagliptin (56% vs. 55%, p = 0.93). BG >180 mg/dL was observed in 19% and 11% of patients treated with placebo and sitagliptin, respectively, p = 0.36. Both treatment groups had resulted in similar postoperative BG (148.9 ± 29.4 mg/dL vs. 146.9 ± 35.2 mg/dL, p = 0.73). There were no differences in length-of-stay (4 vs. 3 days, p = 0.84), ICU transfer (3% vs. 5%, p = 1.00), hypoglycemia <70 mg/dL (6% vs. 11%, p = 0.45), and complications (14% vs. 18%, p = 0.76).

CONCLUSION

Preoperative treatment with sitagliptin did not prevent stress hyperglycemia or complications in individuals without diabetes undergoing surgery.

Myocyte membrane and microdomain modifications in diabetes: determinants of ischemic tolerance and cardioprotection

Cardiovascular disease, predominantly ischemic heart disease (IHD), is the leading cause of death in diabetes mellitus (DM). In addition to eliciting cardiomyopathy, DM induces a ‘wicked triumvirate’: (i) increasing the risk and incidence of IHD and myocardial ischemia; (ii) decreasing myocardial tolerance to ischemia–reperfusion (I–R) injury; and (iii) inhibiting or eliminating responses to cardioprotective stimuli. Changes in ischemic tolerance and cardioprotective signaling may contribute to substantially higher mortality and morbidity following ischemic insult in DM patients. Among the diverse mechanisms implicated in diabetic impairment of ischemic tolerance and cardioprotection, changes in sarcolemmal makeup may play an overarching role and are considered in detail in the current review. Observations predominantly in animal models reveal DM-dependent changes in membrane lipid composition (cholesterol and triglyceride accumulation, fatty acid saturation vs. reduced desaturation, phospholipid remodeling) that contribute to modulation of caveolar domains, gap junctions and T-tubules. These modifications influence sarcolemmal biophysical properties, receptor and phospholipid signaling, ion channel and transporter functions, contributing to contractile and electrophysiological dysfunction, cardiomyopathy, ischemic intolerance and suppression of protective signaling. A better understanding of these sarcolemmal abnormalities in types I and II DM (T1DM, T2DM) can inform approaches to limiting cardiomyopathy, associated IHD and their consequences. Key knowledge gaps include details of sarcolemmal changes in models of T2DM, temporal patterns of lipid, microdomain and T-tubule changes during disease development, and the precise impacts of these diverse sarcolemmal modifications. Importantly, exercise, dietary, pharmacological and gene approaches have potential for improving sarcolemmal makeup, and thus myocyte function and stress-resistance in this ubiquitous metabolic disorder.

Greater functional improvement in patients with diabetes after rehabilitation following cardiac surgery

BACKGROUND

Diabetes increases the risk of in-hospital complications in medical or surgical patients. Few data are available in the rehabilitation phase after cardiac surgery.

AIM

To assess the influence of diabetes on outcome and complication rate in the rehabilitation phase after cardiac surgery.

METHODS

Data prospectively recorded in the Hospital Information System from 5261 patients consecutively admitted between 1 January 2008 and 31 May 2013 for a comprehensive cardiac rehabilitation programme directly after cardiac surgery were analysed retrospectively.

RESULTS

The study cohort included 1285 (24%) patients with diabetes and 3976 (76%) without. Coronary artery bypass graft (CABG) was more frequent in patients with diabetes (58% vs. 37%, P < 0.01), and valvular surgery was more frequent in patients without diabetes (37% vs. 22%, P < 0.01). Patients with diabetes were more disabled after surgery, with severe disability (Barthel Index < 60) observed in 22% (vs. 17% in patients without diabetes, P < 0.001). During rehabilitation, complications were more frequent in patients with diabetes than those without (28% vs. 21%, P < 0.01); in particular, patients with diabetes had more infections, heart failure and more difficult surgical wound healing. However, the improvement in the Barthel Index was greater in patients with diabetes (+16 ± 15) than without (+13 ± 15, P < 0.001).

CONCLUSIONS

In a large cohort of patients directly admitted to an early inpatient rehabilitation programme after cardiac surgery, those with diabetes were more disabled. Nonetheless, and despite the higher rate of complications, patients with diabetes had the greatest benefit in terms of functional improvement.

Randomized study of basal-bolus insulin therapy in the inpatient management of patients with type 2 diabetes undergoing general surgery (RABBIT 2 surgery)

OBJECTIVE

The optimal treatment of hyperglycemia in general surgical patients with type 2 diabetes mellitus is not known.

RESEARCH DESIGN AND METHODS

This randomized multicenter trial compared the safety and efficacy of a basal-bolus insulin regimen with glargine once daily and glulisine before meals (n = 104) to sliding scale regular insulin (SSI) four times daily (n = 107) in patients with type 2 diabetes mellitus undergoing general surgery. Outcomes included differences in daily blood glucose (BG) and a composite of postoperative complications including wound infection, pneumonia, bacteremia, and respiratory and acute renal failure.

RESULTS

The mean daily glucose concentration after the 1st day of basal-bolus insulin and SSI was 145 ± 32 mg/dL and 172 ± 47 mg/dL, respectively (P < 0.01). Glucose readings <140 mg/dL were recorded in 55% of patients in basal-bolus and 31% in the SSI group (P < 0.001). There were reductions with basal-bolus as compared with SSI in the composite outcome [24.3 and 8.6%; odds ratio 3.39 (95% CI 1.50-7.65); P = 0.003]. Glucose <70 mg/dL was reported in 23.1% of patients in the basal-bolus group and 4.7% in the SSI group (P < 0.001), but there were no significant differences in the frequency of BG <40 mg/dL between groups (P = 0.057).

CONCLUSIONS

Basal-bolus treatment with glargine once daily plus glulisine before meals improved glycemic control and reduced hospital complications compared with SSI in general surgery patients. Our study indicates that a basal-bolus insulin regimen is preferred over SSI in the hospital management of general surgery patients with type 2 diabetes.

Management of type 2 diabetes: evolving strategies for the treatment of patients with type 2 diabetes

The prevalence of type 2 diabetes continues to increase at an alarming rate around the world, with even more people being affected by prediabetes. Although the pathogenesis and long-term complications of type 2 diabetes are fairly well known, its treatment has remained challenging, with only half of the patients achieving the recommended hemoglobin A(1c) target. This narrative review explores the pathogenetic rationale for the treatment of type 2 diabetes, with the view of fostering better understanding of the evolving treatment modalities. The diagnostic criteria including the role of hemoglobin A(1c) in the diagnosis of diabetes are discussed. Due attention is given to the different therapeutic maneuvers and their utility in the management of the diabetic patient. The evidence supporting the role of exercise, medical nutrition therapy, glucose monitoring, and antiobesity measures including pharmacotherapy and bariatric surgery is discussed. The controversial subject of optimum glycemic control in hospitalized and ambulatory patients is discussed in detail. An update of the available pharmacologic options for the management of type 2 diabetes is provided with particular emphasis on newer and emerging modalities. Special attention has been given to the initiation of insulin therapy in patients with type 2 diabetes, with explanation of the pathophysiologic basis for insulin therapy in the ambulatory diabetic patient. A review of the evidence supporting the efficacy of the different preventive measures is also provided.

Prevalence and clinical outcome of hyperglycemia in the perioperative period in noncardiac surgery

OBJECTIVE

Hospital hyperglycemia, in individuals with and without diabetes, has been identified as a marker of poor clinical outcome in cardiac surgery patients. However, the impact of perioperative hyperglycemia on clinical outcome in general and noncardiac surgery patients is not known.

RESEARCH DESIGN AND METHODS

This was an observational study with the aim of determining the relationship between pre- and postsurgery blood glucose levels and hospital length of stay (LOS), complications, and mortality in 3,184 noncardiac surgery patients consecutively admitted to Emory University Hospital (Atlanta, GA) between 1 January 2007 and 30 June 2007.

RESULTS

The overall 30-day mortality was 2.3%, with nonsurvivors having significantly higher blood glucose levels before and after surgery (both P < 0.01) than survivors. Perioperative hyperglycemia was associated with increased hospital and intensive care unit LOS (P < 0.001) as well as higher numbers of postoperative cases of pneumonia (P < 0.001), systemic blood infection (P < 0.001), urinary tract infection (P < 0.001), acute renal failure (P = 0.005), and acute myocardial infarction (P = 0.005). In multivariate analysis (adjusted for age, sex, race, and surgery severity), the risk of death increased in proportion to perioperative glucose levels; however, this association was significant only for patients without a history of diabetes (P = 0.008) compared with patients with known diabetes (P = 0.748).

CONCLUSIONS

Perioperative hyperglycemia is associated with increased LOS, hospital complications, and mortality after noncardiac general surgery. Randomized controlled trials are needed to determine whether perioperative diabetes management improves clinical outcome in noncardiac surgery patients.

Early and late outcome after coronary artery bypass surgery in diabetic patients

OBJECTIVE

To determine the impact of diabetes on outcome after coronary artery bypass surgery.

DESIGN

We matched 866 diabetic patients with non-diabetic controls in regards to gender, age, left ventricular ejection fraction, body mass index, presence of unstable angina and history of myocardial infarction, and day of surgery. The 30-d mortality and morbidity were evaluated with univariate analysis and survival and freedom from cardiac death were assessed with the Kaplan-Meier method.

RESULTS

Follow-up time was 69+/-37 months. The 30-d mortality was 2.0% in the diabetic group and 1.0% in the non-diabetic group (p=0.15). Postoperative morbidity did not differ between groups. Cumulative 5- and 10-year survival rates were 89 and 71% in diabetics and 94 and 84% in non-diabetics (p=0.001). During follow-up, there was no difference between groups in regards to repeat revascularization.

CONCLUSIONS

The 30-d mortality was equally low in diabetic and non-diabetic patients with severe coronary artery disease. However, long-term survival was significantly lower in the diabetic group than in the non-diabetic group.

Mortality in diabetic patients undergoing non-cardiac surgery: a 7-year follow-up study

BACKGROUND

The prognosis of diabetic patients after non-cardiac surgery remains controversial. This study was designed to compare the long-term mortality between diabetic and non-diabetic control patients undergoing non-cardiac surgery and to evaluate the possible risk factors.

METHODS

We investigated 274 consecutive diabetic patients and 282 non-diabetic control patients who underwent non-cardiac surgery within 1 year in a tertiary care hospital in Finland. The control group was matched for the same type of operations. Patients were followed for up to 7 years on average. The main outcome measure was mortality within 7 years.

RESULTS

Mortality both in the short-term postoperatively (< or =21 days) and in the long-term (up to 87 (1/2) months) was significantly higher in the diabetic patients compared with the non-diabetic group: 3.5 vs. 0% (P<0.05) and 37.2 vs. 15% (P<0.00001), respectively. The major causes of death among diabetic subjects were diseases of the cardiovascular system (56.8%) compared with non-diabetic patients (18.6%), P<0.0001. We found that diabetes mellitus per se is not a risk factor for post-operative mortality but a combination of variables had a significant effect on both short- and long-term mortality.

CONCLUSION

Diabetic patients undergoing non-cardiac surgery had a significantly higher incidence of short-term post-operative and long-term mortality compared with non-diabetic subjects. We propose a model of predictors of death among diabetic individuals undergoing non-cardiac surgery within a 7-year follow-up. The majority of deaths were associated with cardiovascular diseases.

The Influence of Diabetes Mellitus in Patients Undergoing Coronary Artery Bypass Graft Surgery: A Prospective Cohort Study

This study was conducted to prospectively assess if there are any outcome differences between patients undergoing coronary artery bypass graft surgery with and without diabetes. This is an 11-year, prospective, hospitalization cohort study. Data were collected on 225 variables. A total of 8935 patients were available for our analysis (6023 nondiabetics, 319 diet-controlled diabetics, 1636 diabetics on oral medications, 957 insulin-controlled diabetics). Compared with nondiabetics, diet-treated diabetics possessed four significant comorbidities, diabetics treated with oral medications possessed 12 significant comorbidities, and insulin-treated diabetics possessed 13 significant comorbidities ( P < 0.05). There was no significant difference between diet-treated diabetics and nondiabetics for all outcomes. Diabetics treated with oral medications possessed a longer length of stay [relative risk (RR), 1.09; CI, 1.08–1.10], longer intensive care unit length of stay (RR, 1.56; CI, 1.12–2.00), and more intraoperative complications (RR, 1.42; CI, 1.12–1.66). Insulin-treated diabetics possessed more neurological complications (RR, 2.39; CI, 1.52–3.77), wound complications (RR, 2.42; CI, 1.19–4.95), and renal complications (RR, 2.43; CI, 1.70–3.49), longer length of stay (RR, 1.20; CI, 1.14–1.27), and longer intensive care unit length of stay (RR, 1.33; CI, 1.16–1.48). In diabetics undergoing coronary artery bypass graft surgery, as their diabetes progresses from diet treated with oral medications to insulin-dependent, this is associated with more comorbidities at surgical presentation and more morbidity after surgery.

Risk of death or acute myocardial infarction 10 years after coronary artery bypass surgery in relation to type of diabetes

BACKGROUND

The aim of this study was to assess the long-term risk of death or acute myocardial infarction (AMI) in patients with diabetes mellitus (DM) compared with that in patients without DM after coronary artery bypass grafting (CABG).

METHODS

National registers were used to record death or AMI occurring in 6727 patients who had CABG during 1980 to 1995. Diabetes mellitus in 856 patients (13%) was classified as type 1 (6%) or type 2 treated with insulin (29%), oral drugs (46%), or diet (19%).

RESULTS

The risk of death < or = 30 days of the operation was increased in patients with insulin-treated type 2 DM (odds ratio [OR] 4.6, 95% CI 2.5-8.4) and in those on oral antidiabetic drugs (OR 2.0, 95% CI 1.0-3.8), but not in diet-treated diabetic patients, compared with that in patients without diabetes. At 10 years, the relative risk of death or having an AMI was 1.8 (95% CI 1.5-2.2) in insulin-treated patients and 1.4 (95% CI 1.2-1.7) in patients on oral drugs. No increased risk of late death or AMI was observed in diet-treated patients with diabetes compared with patients without diabetes. Survival at 10 years without an AMI was 40% in insulin-treated type 2 diabetic patients, 48% if on oral drugs, and 59% if diet managed, compared with 66% in nondiabetic patients.

CONCLUSION

Type 2 DM requiring insulin treatment or oral antidiabetic drugs is associated with an increased early and long-term risk of death or AMI after CABG, whereas diet-treated patients have a risk similar to that in patients without diabetes.

Perioperative glucose control in the diabetic or nondiabetic patient

Patients with diabetes are more likely to undergo surgery than nondiabetics, and maintaining glycemic control in subjects with diabetes can be challenging during the perioperative period. Surgery in diabetic patients is associated with longer hospital stay, higher health care resource utilization, and greater perioperative mortality. In addition, several observational and interventional studies have indicated that hyperglycemia is associated with adverse clinical outcomes in surgical and critically ill patients. This paper reviews the pathophysiology of hyperglycemia during trauma and surgical stress and will provide practical recommendations for the preoperative, intraoperative, and postoperative care of diabetic patients.

The diabetic surgical patient

PURPOSE OF REVIEW

This review summarizes the current progress in disease classification, pathophysiology and management of diabetes mellitus with a special focus on treatment modalities and recommendations for the practicing anesthesiologist.

RECENT FINDINGS

The revised classification of diabetes mellitus emphasizes disease cause and eliminates any reference to age-of-onset and insulin therapy. Hyperglycemia has emerged as an important marker of outcome in the operating room. Intensive insulin therapy promises to reduce health risk in the surgical and critical care setting. Perioperative beta-blocker and statin therapy are likely to reduce cardiac morbidity and mortality in diabetic patients. Promotility therapy (with metoclopromide) intended to reduce the aspiration risk of diabetic gastroparesis is likely over-utilized and may only be indicated for diabetics with poor glucose control and high hemoglobin A1c levels.

SUMMARY

According to World Health Organization projections, anesthesiologists can expect to care for more diabetic patients than ever before. Diabetes and its associated complications present unique challenges to the perioperative physician. As biomedical research continues to unravel the genetic, cellular and molecular mechanisms of this complex metabolic disease, our specialty must be prominently involved in the design and testing of innovative treatments to protect the diabetic patient from the risks of surgery and anesthesia.

Cardiac surgery in an Iranian teaching hospital: outcome and risk factors

Cardiac surgery in Iran has been associated with different facilities, equipment and patient populations in comparison to countries from which most of the academic papers used for identification of risk factors related to outcome and subsequent establishment of risk stratification models originate from. During a 15-month period all patients admitted for adult cardiac surgery using cardiopulmonary bypass (CBP) in a university affiliated teaching hospital were enrolled in a prospective study. Appropriate statistical tests were used to analyze data for mortality and morbidity. There were 730 adults (63% male, 37% female), with age ranged from 16 to 82 (mean, 51.4 +/- 14.4). A mortality rate of 5.3% and morbidity of 14.8% (major + minor) were observed in the whole group. Factors correlated with mortality were: age (p = 0.019), emergency surgery (p < 0.0001), redo cardiac surgery (p = 0.01), left ventricular (LV) aneurysm (p < 0.001), presence of catastrophic states (p < 0.001), low ejection fraction (p = 0.04), history of hypertension (p = 0.05), the individual surgeon (p < 0.0001), and CPB duration (p < 0.0001). Factors affecting morbidity included: female gender (p = 0.04), age (p = 0.03), emergency surgery (p = 0.001), redo surgery (p = 0.008), and catastrophic states (p < 0.001). The mortality in our study group may be compared with reports presented in the literature. Factors such as age, emergency surgery, redo cardiac surgery, and catastrophic states are statistically related to both mortality and morbidity.

The Influence of Type 2 Diabetes Mellitus in Patients Undergoing Coronary Artery Bypass Graft Surgery

OBJECTIVE

To prospectively assess whether there are any outcome differences between patients with and without type 2 diabetes mellitus undergoing coronary artery bypass graft (CABG) surgery.

STUDY DESIGN

This was an 8-year, prospective hospitalization cohort study. Data were collected on 225 variables concurrently with hospital admission. The main outcome was total operative mortality. In addition, we evaluated 12 morbidity outcomes. To minimize confounding, we controlled for 16 other variables.

RESULTS

A total of 6,711 patients were available for our analysis (diabetic patients, 2,178; and nondiabetic patients, 4,533). The diabetic patients were significantly more likely to be women, to have more left ventricular hypertrophy, to have a history of cerebrovascular disease, hypertension, and COPD, to have a greater body surface area, to have higher creatinine levels, to be African-American, to have undergone more elective procedures, to have a shorter pump time, and to have less of a history of tobacco use compared to nondiabetic patients (p < 0.05). Multiple regression analysis found no significant difference between the two groups for all 12 morbidity outcomes of interest. Diabetic patients experienced significantly more mortality than nondiabetic patients (relative risk, 1.67; 95% confidence interval, 1.20 to 2.30; p < 0.004).

CONCLUSION

Patients with type 2 diabetes who are undergoing CABG surgery experience significantly more total operative mortality compared to nondiabetic patients, even after controlling for multiple variables. There was no difference between the groups for 12 morbidity outcomes.

Perioperative management of diabetic patients

Diabetes mellitus is the most common metabolic disease. New classifications have recently been proposed by the American Diabetes Association (ADA) and the World Health Organization (WHO). Type 1 (formerly insulin-dependent diabetes mellitus IDDM) is immune-mediated and leads to absolute insulin deficiency. Type 2 diabetes (formerly non-insulin-dependent diabetes mellitus [NIDDM]) is a disease of adult onset and is associated with insulin resistance. Type 3 corresponds to a wide range of specific types of diabetes, including various genetic defects of beta-cell function and insulin action, diseases of exocrine pancreas, endocrinopathies, and drug-induced diabetes. Type 4 is gestational diabetes (Table 1). Diabetics undergoing surgery have increased mortality, and type 1 diabetics are particularly at risk of postoperative complications. Wound complications are increased in diabetics, and healing is severely impaired when glycemic control is poor. However, with the use of modern management plans, the major outcome measures of surgery are comparable in diabetic and nondiabetic patients. Successful management of surgery in diabetic patients requires simple and safe protocols, which are fully understood by all staff and a close liaison among the surgeons, diabetes care team, and anesthetists. There is no consensus on the optimal metabolic management of the diabetic patient during surgery. Several surveys have highlighted the inconsistency with which surgical problems are managed in diabetic patients. The aim of this article is to provide protocols to achieve sensible and practical glycemic control in diabetic patients undergoing surgery.

Coronary Artery Bypass Surgery in Diabetic Patients

BACKGROUND

Cardiovascular disease is a major cause of morbidity and mortality in patients with diabetes. This study examines the impact of diabetes on mortality and morbidity following coronary artery bypass surgery.

METHODS

We retrospectively analyzed 590 consecutive patients after coronary artery bypass grafting in 1998. Reoperations and combined procedures were excluded. A total of 137 diabetic (23.2%) and 453 nondiabetic patients were evaluated. Among the diabetics, 53 were treated with insulin and 84 were non-insulin-dependent. Diabetics suffered more frequently from hypertension, peripheral vascular disease, and more often had an increased body mass index (BMI).

RESULTS

There was no significant difference in mortality and major complications among insulin-dependent diabetics, non-insulin-dependent diabetics, and nondiabetic patients. Diabetics suffered more often from superficial sternal wound infection and had a higher incidence of superficial wound infections at the vein harvest site.

CONCLUSION

The present study suggests that diabetes increases the risk of superficial wound infections after coronary artery bypass grafting. But diabetics do not necessarily have an increased risk of major complications and mortality.

Perioperative hyperglycemia is a strong correlate of postoperative infection in type II diabetic patients after coronary artery bypass grafting

This study was planned to assess the relationship of perioperative glycemic control to the subsequent risk of infectious complications and to compare early clinical outcomes of coronary artery bypass surgery in diabetics with nondiabetics in a single center. A total of 1090 adults who underwent coronary artery surgery in a five year period were included in a retrospective cohort study based on available chart review. Of 1090 patients, 400 had type II diabetes mellitus. Intraoperative and postoperative blood glucose levels in diabetic group were manipulated by means of a continuous insulin infusion. Data of pre- and postoperative blood glucose levels were evaluated with respect to postoperative infection risk for diabetics. Risks of early mortality, cerebrovascular accident, and postoperative infection in diabetic patients were compared with the nondiabetic group. High preoperative mean glucose levels were the main risk factor for the development of postoperative infection (p = 0.012 and p = 0.028 for the mean glucose levels 1 and 2 days before operation, respectively). For diabetic group, of 400 patients 20 (5%) were diagnosed to have postoperative infection (superficial sternal wound in 3 (0.75%), donor site infection in 4 (1%), mediastinitis in 5 (1.25%), urinary tract infection in 6 (1.5%), and lung infection in 2 (0.5%) patients). The diabetic group had significantly higher prevalence of mediastinitis, donor site infection, urinary tract infection and total infection (p values were 0.048, 0.013, 0.009, and 0.044, respectively). Early mortality was higher among diabetics than in nondiabetics (1.73% vs 3%, p = 0.048) but the risk of cerebrovascular accident in diabetics was not greater than in nondiabetics in early period. In patients with diabetes who undergo coronary artery bypass surgery, preoperative hyperglycemia is an independent predictor of short-term infectious complications and total length of stay in hospital.

Early postoperative outcome and medium-term survival in 540 diabetic and 2239 nondiabetic patients undergoing coronary artery bypass grafting

BACKGROUND

An increasing proportion of patients undergoing coronary artery bypass grafting (CABG) are diabetics. Patient characteristics, early postoperative outcome, and midterm survival in diabetic patients after CABG were investigated.

METHODS

A total of 2779 consecutive patients undergoing isolated CABG during 1995 to 1999 were studied, 19.4% of whom had diabetes mellitus. Demographic and peri-procedural data were registered prospectively in a computerized institutional database.

RESULTS

The diabetic group was younger and included a higher proportion of women, and patients with hypertension, triple-vessel disease, and unstable angina. They required a higher number of bypasses, and longer cross-clamp and cardiopulmonary bypass times. Intensive care unit and hospital stays were prolonged and the need for inotropic agents, hemotransfusions, and dialysis was higher in the diabetic group. Renal failure, stroke (4.3% versus 1.7%), mediastinitis, and wound infections were more frequently encountered. Thirty-day mortality was 2.6% versus 1.6% (p = 0.15). Cumulative 5-year survival was 84.4% versus 91.3% (p < 0.001).

CONCLUSIONS

Short-term mortality was acceptable in diabetic patients after CABG but they had increased postoperative morbidity in comparison with nondiabetic patients, particularly with regard to renal function, cerebral complications, and infections. Midterm survival was impaired in diabetic patients mainly because of a less favorable outcome in patients treated with insulin.

Diabetes mellitus increases short-term mortality and morbidity in patients undergoing coronary artery bypass graft surgery

OBJECTIVES

The aim of this study was to determine the impact of diabetes mellitus (DM) on short-term mortality and morbidity in patients undergoing coronary artery bypass surgery (CABG).

BACKGROUND

Diabetes mellitus is present in approximately 20% to 30% of patients undergoing CABG, and the impact of diabetes on short-term outcome is unclear.

METHODS

We performed a retrospective cohort study in 434 hospitals from North America. The study population included 146,786 patients undergoing CABG during 1997: 41,663 patients with DM and 105,123 without DM. The primary outcome was 30-day mortality. Secondary outcomes were in-hospital morbidity, infections and composite outcomes of mortality or morbidity and mortality or infection.

RESULTS

The 30-day mortality was 3.7% in patients with DM and 2.7% in those without DM; the unadjusted odds ratio was 1.40 (95% confidence interval [CI], 1.31 to 1.49). After adjusting for other baseline risk factors, the overall adjusted odds ratio for diabetics was 1.23 (95% CI, 1.15 to 1.32). Patients treated with oral hypoglycemic medications had adjusted odds ratio 1.13; 95% CI, 1.04 to 1.23, whereas those on insulin had an adjusted odds ratio 1.39; 95% CI, 1.27 to 1.52. Morbidity, infections and the composite outcomes occurred more commonly in diabetic patients and were associated with an adjusted risk about 35% higher in diabetics than nondiabetics, particularly among insulin-treated diabetics (adjusted risk between 1.5 to 1.61).

CONCLUSIONS

Diabetes mellitus is an important risk factor for mortality and morbidity among those undergoing CABG. Research is needed to determine if good control of glucose levels during the perioperative time period improves outcome.

Postoperative management of the diabetic patient

Diabetic patients are at increased risk for adverse outcomes of surgery. These adverse outcomes are related to pre-existing complications of diabetes, especially atherosclerotic disease, nephropathy (and perhaps increased susceptibility to other renal toxins), and peripheral and autonomic neuropathy. Hyperglycemia is associated with likely risks for poorer wound healing, increased susceptibility to infection, and probable loss of administered nutrients through glycosuria. Insulin use has the flexibility of timing and dose in the postoperative management of most diabetic patients. The combinations of intermediate-acting and long-acting insulins and short-acting insulins usually are related to the experience and preferences of the treating physicians and allied health professionals. Intravenous insulin (always R) may be limited to administration in the ICU because of the need for frequent blood glucose monitoring and rapidity of glucose response to intravenous insulin. The use of short-acting insulin analogues has been shown to work well as premeal insulin or for rapidly treating marked hyperglycemia in the outpatient setting. Meal delivery in the hospitalized patient may not be timed as precisely as in the home situation. Nurses may be responsible for many patients. The rapid-acting analogues may be associated with increased risk for hypoglycemia in the hospitalized patient if insulin cannot be given immediately before a meal. These rapid-acting insulin analogues usually are limited to circumstances in which the patient can determine the dose and self-administer just before ingestion of the meal. The long-acting insulin analogues may not afford enough flexibility in many situations in which daily dosages changes are occurring in intermediate-acting and long-acting insulins. Oral glucose-lowering agent use in the postoperative state usually is limited to selected patients, including patients who have been on such agents before surgery, who have only mild elevations of blood glucose, who are able to ingest oral medications, and who do not have significant comorbid conditions (or significant risk for such conditions) that may be contraindications to use of such agents (see Table 3). Sulfonylureas and other insulin secretagogues (e.g., meglitinide, nateglinide) lower glucoses acutely. The risk for hypoglycemia is slightly less with the nonsulfonylurea agents. Efficacy and side effects limit the use of carbohydrase inhibitors for hospitalized patients. The glucose-lowering effects of biguanides and thiazolidinediones usually are not rapid enough for hospitalized patients who have never taken these medications. For patients who have been on a biguanide or thiazolidinedione before admission, these agents often are restarted in the postoperative period when oral intake of medications is possible and hepatic and renal function are stable. The hospital period affords an opportunity to review long-term management issues related to diabetes and its complications. Instruction on the importance of medical nutrition therapy, glycemic control, management of hypertension, dyslipidemia, and aspirin use as well as basic guidelines for foot care should be carried out during the hospitalization and at the time of discharge. Similarly, appropriate arrangements for medical nutrition therapy, general diabetes education (especially for newly diagnosed diabetic patients), and regular medical follow-up are important to ensure long-term, excellent surgical and medical outcomes.

The influence of general health status and social support on symptomatic outcome following coronary artery bypass grafting

OBJECTIVES

To assess health status, level of social support, and presence of coronary artery disease risk factors before and after coronary artery bypass grafting (CABG); to assess symptomatic relief approximately 12 months postoperatively; and to examine the association between preoperative health status and recurrence of symptoms.

DESIGN

Observational study.

SETTING

Preoperatively, in hospital outpatient department (1995-1996); postoperatively, at home (1996-97).

SUBJECTS AND METHODS

Patients awaiting elective CABG were recruited one month before the expected date of operation. Preoperative assessment included severity of symptoms, coronary artery disease risk factors, short form 36 (SF-36) questionnaire, and social activities questionnaire. The presence and severity of angina and breathlessness were reported postoperatively (mean 16.4 months). Multiple regression analysis was used to identify factors associated with improved outcome following CABG.

MAIN OUTCOME MEASURE

Patient reported presence and severity of angina and breathlessness.

RESULTS

183 patients were followed for a mean of 16. 4 months after CABG. Angina and breathlessness were completely relieved in 55% and 36% of patients, respectively. In patients with residual symptoms, the severity was significantly reduced (angina p < 0.001; breathlessness, p = 0.02). Patients with low SF-36 scores and low social network scores preoperatively were less likely to be relieved of symptoms (p < 0.001). Health status and social support levels preoperatively were lower than in other reported coronary artery disease patients groups. Preoperatively, coronary artery disease risk factors were higher than recommended in current guidelines: 67.4% had raised plasma cholesterol, 39.0% were hypertensive, 80% were moderately obese, and 22.9% were smokers.

CONCLUSIONS

Recurrence of symptoms exceeded other published studies. Patients' perception of general health, symptoms, and social support influences outcome.

Assessment of changes in general health status using the short-form 36 questionnaire 1 year following coronary artery bypass grafting

OBJECTIVE

The problem addressed in the study was to gain a greater understanding of the health benefits of coronary artery bypass grafting (CABG). The purpose of the study was to assess general health status, using the short-form (SF)-36 questionnaire, approximately 12 months following CABG, and to document any associations between pre-operative health status, level of social support, coronary artery disease (CAD) risk factors, CAD symptom severity and post-operative health status.

METHODS

The study was prospective and observational in design and included assessments at two time points, namely pre-operatively in a hospital outpatient department (1995-1996) and post-operatively at home (1996-1997). Two hundred and fourteen patients awaiting elective CABG were recruited a month before the expected date of operation. Pre-operative assessment included: (1), severity of symptoms; (2), CAD risk factors; (3), SF-36 questionnaire; and (4), social activities questionnaire. Post-operative assessment measured health status using the SF-36 instrument (mean, 16.4 months). Correlation and multiple linear regression analyses were used to identify factors associated with improved health status following CABG.

RESULTS

Two hundred and fourteen patients were assessed pre-operatively and underwent CABG. There was a 4.8% 30-day mortality rate, and 183 patients were followed for a mean of 16.4 months after CABG. SF-36 scores following CABG were improved across all of the eight domains (P<0.001). A higher social network score and higher pre-operative health status were associated with improved health status. Patients with lower health levels (SF-36 scores) prior to CABG were less likely to gain improvement in health (SF-36 scores) following CABG. Lower SF-36 scores following operation were influenced by the presence of diabetes mellitus, cigarette smoking, younger age, a high socio-economic deprivation category and higher alcohol intake. Many patients had uncorrected CAD risk factors at pre-operative assessment.

CONCLUSIONS

The SF-36 instrument was shown to be a useful and sensitive tool to assess differences and changes in the general health status of patients before and following CABG. High levels of social support were associated with improved health status post-operatively. Lower pre-operative general health status, the presence of diabetes mellitus and cigarette smoking were associated with poorer post-operative general health status.

How deadly is the "deadly quartet"? A post-CABG evaluation

OBJECTIVES

The aim of the study was to determine the value of a cluster of metabolic risk factors in predicting mortality after coronary artery bypass surgery (CABG).

BACKGROUND

The "deadly quartet" of metabolic risk factors (i.e., obesity, diabetes, hypertension, and hypertriglyceridemia) has been associated with coronary heart disease in healthy population studies. The expected influence of the cluster on survival in secondary prevention remains untested overall as well as by gender.

METHODS

Patients with lipid profiles undergoing primary isolated CABG (n = 6,428) between 1987 and 1992 were followed a median of eight years. Cox models were used to evaluate all-cause mortality. Metabolic risk factors were incorporated as the sum of deadly quartet risk factors present in each patient (0 to 4). The role of gender as it relates to survival and metabolic risk clusters was also examined.

RESULTS

The sum of deadly quartet risk factors showed a significant relationship to mortality as the hazard ratio increased from 1.64 (confidence interval [CI] = 1.34-2.01) for one risk factor to 3.95 (2.73-5.69) for four risk factors. Annualized mortality ranged from 1% per year in patients with no risk factors to 3.3% per year in patients with all four risk factors. Within gender, the hazard ratio associated with four risk factors was 2.58 for men and 13.39 for women. The expected clustering of risk factors was 8% compared to the observed clustering of 10% in men and 21% in women.

CONCLUSIONS

This cohort showed risk factor clustering beyond that expected due to chance, particularly in women. Even after revascularization, survival is diminished for patients with members of a family of metabolic risk factors at the time of surgery.

Risk factors and outcome in European cardiac surgery: analysis of the EuroSCORE multinational database of 19030 patients

OBJECTIVE

To assess risk factors for mortality in cardiac surgical adult patients as part of a study to develop a European System for Cardiac Operative Risk Evaluation (EuroSCORE).

METHODS

From September to November 1995, information on risk factors and mortality was collected for 19030 consecutive adult patients undergoing cardiac surgery under cardiopulmonary bypass in 128 surgical centres in eight European states. Data were collected for 68 preoperative and 29 operative risk factors proven or believed to influence hospital mortality. The relationship between risk factors and outcome was assessed by univariate and logistic regression analysis.

RESULTS

Mean age (+/- standard deviation) was 62.5+/-10.7 (range 17-94 years) and 28% were female. Mean body mass index was 26.3+/-3.9. The incidence of common risk factors was as follows: hypertension 43.6%, diabetes 16.7%, extracardiac arteriopathy 2.9%, chronic renal failure 3.5%, chronic pulmonary disease 3.9%, previous cardiac surgery 7.3% and impaired left ventricular function 31.4%. Isolated coronary surgery accounted for 63.6% of all procedures, and 29.8% of patients had valve operations. Overall hospital mortality was 4.8%. Coronary surgery mortality was 3.4% In the absence of any identifiable risk factors, mortality was 0.4% for coronary surgery, 1% for mitral valve surgery, 1.1% for aortic valve surgery and 0% for atrial septal defect repair. The following risk factors were associated with increased mortality: age (P = 0.001), female gender (P = 0.001), serum creatinine (P = 0.001), extracardiac arteriopathy (P = 0.001), chronic airway disease (P = 0.006), severe neurological dysfunction (P = 0.001), previous cardiac surgery (P = 0.001), recent myocardial infarction (P = 0.001), left ventricular ejection fraction (P = 0.001), chronic congestive cardiac failure (P = 0.001), pulmonary hypertension (P = 0.001), active endocarditis (P = 0.001), unstable angina (P = 0.001), procedure urgency (P = 0.001), critical preoperative condition (P = 0.001) ventricular septal rupture (P = 0.002), noncoronary surgery (P = 0.001), thoracic aortic surgery (P = 0.001).

CONCLUSION

A number of risk factors contribute to cardiac surgical mortality in Europe. This information can be used to develop a risk stratification system for the prediction of hospital mortality and the assessment of quality of care.

Prospective, randomized trial comparing blood and oxygenated crystalloid cardioplegia in reoperative coronary artery bypass grafting

OBJECTIVES

Reoperative coronary artery bypass grafting presents unique challenges for myocardial preservation. The purpose of this study was to compare oxygenated blood cardioplegia with oxygenated crystalloid cardioplegia during reoperative coronary artery bypass grafting using transesophageal echocardiography to assess regional wall motion of the left ventricle before and after cardiopulmonary bypass.

METHODS

Sixty-one patients undergoing reoperative coronary artery bypass grafting were prospectively randomized to receive oxygenated blood cardioplegia or oxygenated crystalloid cardioplegia delivered with a combined antegrade-retrograde technique. Transgastric short axis views of the left ventricle were made with transesophageal echocardiography during the operation before cardiopulmonary bypass and immediately after cardiopulmonary bypass. Regional wall motion was graded by a blinded observer, and before cardiopulmonary bypass scores were compared with after cardiopulmonary bypass scores.

RESULTS

No significant differences were found in the change in regional wall motion score from before cardiopulmonary bypass to after cardiopulmonary bypass between the blood and crystalloid cardioplegia groups.

CONCLUSIONS

This study found blood and crystalloid cardioplegia to be equally efficacious for myocardial preservation during reoperative coronary artery bypass grafting.