Elevated preoperative hemoglobin A1c level is predictive of adverse events after coronary artery bypass surgery

Elevated postoperative blood glucose and preoperative hemoglobin A1C are associated with increased wound complications following total joint arthroplasty

BACKGROUND

Diabetes is an established risk factor for complications following total joint arthroplasty. However, the correlation between postoperative blood glucose and preoperative hemoglobin A1C levels with complications following total joint arthroplasty is not well described.

METHODS

All patients undergoing elective primary total joint arthroplasty at our institution from 2004 through 2011 with both postoperative blood glucose and preoperative hemoglobin A1C levels were identified in a retrospective review. From among 1702 patients, those with wound complications within thirty days after the index arthroplasty were identified. A control group matched for exact age, sex, procedure, tourniquet use, surgical approach, and use of antibiotic cement was also created. Thirty patients met the study group inclusion criteria. The mean patient age was seventy-two years (range, fifty-three to eighty-nine years); the majority (53%) of patients were female.

RESULTS

The odds ratio for developing a wound complication was 3.75 (95% confidence interval, 1.25 to 11.22; p = 0.02) in patients with a mean postoperative glucose of >200 mg/dL, 3.0 (95% confidence interval, 0.97 to 9.30; p = 0.08) in patients with a maximum postoperative blood glucose of >260 mg/dL, and 9.0 (95% confidence interval, 1.14 to 71.20; p = 0.03) in patients with a preoperative hemoglobin A1C value of >6.7%.

CONCLUSIONS

Patients with a mean postoperative blood glucose of >200 mg/dL or a preoperative hemoglobin A1C level of >6.7% are at increased risk for wound complications following elective primary total joint arthroplasty. These results show that poor preoperative and postoperative glucose control is independently associated with wound complications.

Improving long term outcome for diabetic patients undergoing surgical revascularization by use of the radial artery conduit: a propensity matched study

Background

Diabetes predicts worse outcomes after coronary artery bypass grafting (CABG) We hypothesized that a strategy using radial artery (RA) conduit(s) would improve outcomes and long term survival for diabetic patients undergoing CABG with Left Internal Thoracic Artery (LITA) and RA grafts, with or without additional saphenous vein (SV) when compared with outcomes for patients bypassed with LITA and SV but no RA.

Methods

A propensity matched study of long term survival in diabetic patients who had isolated first time CABG from January 1995 to June 2010 at an urban academic medical center in New York City. Our primary endpoint was all cause mortality determined from the Social Security Death Index in December 2010.

Results

We compared our 15 year outcomes in diabetic patients after isolated, primary CABG: 642 patients received LITA + RA +/− SV (RA group) vs. 1201 patients who had LITA + SV only (SV group). Propensity scoring for multiple preoperative and operative variables matched 409 patients from each group: 68% were male with an average age of 61 years and ejection fraction averaged 47%. Average grafts per patient was 3.7 for both groups with 2.3 arterial grafts per patient for the RA group. Operative (30 day) mortality was 0.1% RA vs. 1.9% SV, (p<0.0001) For propensity matched patients, mortality was 0.25 RA vs 0.5% SV. (p<0.001) The incidence of major complications was similar in both groups. Kaplan Meier actuarial survival at 1, 5, 10 and 12 years was 98%, 89%, 77 and 70% for RA vs. 96%, 87%, 64% and 59% for SV (p<0.006.) By Cox multivariate analysis significant predictors of mortality were: age, stroke, peripheral vascular disease, COPD, creatinine > 2.5mg/dl and low ejection fraction but only RA use predicted better survival [HR 0.683, CI 0.507- 0.920, p=0.0122].

Conclusion

For diabetic patients having CABG with LITA, use of radial artery conduit adds a substantial and sustained survival advantage compared to LITA and vein. Optimal revascularization for diabetics with multi vessel disease is redefined.

The healing of dental extraction sockets in patients with Type 2 diabetes on oral hypoglycaemics: a prospective cohort

BACKGROUND

The aim of this study was to determine whether there is a difference in delayed healing following dental extractions for Type 2 diabetics on oral hypoglycaemics and non-diabetic patients.

METHODS

Prospective patients referred for dental extractions were recruited into two groups: known diabetics and non-diabetics with no conditions associated with poor healing. All had a random blood glucose level (BGL). Extractions were performed using local anaesthesia. Delayed healing cases were identified and statistical evaluation performed to identify risk factors.

RESULTS

There were 224 Type 2 diabetics on oral hypoglycaemics (BGL 7.51, range 4.1-17.4) and 232 non-diabetics. The diabetic group were older, more males and less smokers than the control group. Twenty-eight patients, 12 (5%) diabetic and 16 (7%) control group, had socket healing delayed for more than one week but all healed in four weeks. There were no statistical differences between delayed healing and age, gender, diabetic state, BGL or smoking. The younger control group had more healing problems.

CONCLUSIONS

The traditional view that diabetics have increased delayed healing was not supported. Type 2 diabetics on oral hypoglycaemics should be treated the same as non-diabetic patients for extractions.

Factors associated with nonunion, delayed union, and malunion in foot and ankle surgery in diabetic patients

The incidence of bone healing complications in diabetic patients is believed to be high after foot and ankle surgery. Although the association of hyperglycemia with bone healing complications has been well documented, little clinical information is available to show which diabetes-related comorbidities directly affect bone healing. Our goal was to better understand the risk factors associated with poor bone healing in the diabetic population through an exploratory, observational, retrospective, cohort study. To this end, 165 diabetic patients who had undergone arthrodesis, osteotomy, or fracture reduction were enrolled in the study to assess the risk factors associated with nonunion, delayed union, and malunion after elective and nonelective foot and/or ankle surgery. Bivariate analyses showed that a history of foot ulcer, peripheral neuropathy, and surgery duration were statistically significantly associated with bone healing complications. After adjusting for other covariates, only peripheral neuropathy, surgery duration, and hemoglobin A1c levels >7% were significantly associated statistically with bone healing complications. Of the risk factors we considered, peripheral neuropathy had the strongest association with bone healing complications.

Perioperative control of blood glucose level in cardiac surgery

It is well recognized that poor perioperative blood glucose (BG) control can increase the risk of infection, cardiovascular accidents, and even death in patients undergoing cardiac surgery. Since it has been reported that tight BG control (80-110 mg/dL) yields better outcomes in critically ill patients, it became a standard of care to control BG using intravenous insulin infusion in ICU. However, it has been debated in terms of the optimal target range whether a strict control with intensive insulin therapy is better than liberal control. Because strict BG control can often cause hypoglycemia, which in turn increases the hospital mortality. In fact, a meta-analysis of randomized clinical trials concluded that tight BG control was not associated with significantly reduced hospital mortality but was associated with an increased risk of hypoglycemia. According to the current published guidelines, it seems to be optimal to control BG level of 140-180 mg/dL in ICU. In terms of more strict BG control (110-140 mg/dL), it may be appropriate in selected patients as long as this can be achieved without significant hypoglycemia.

Glycemic Control during Coronary Artery Bypass Graft Surgery

Hyperglycemia, which occurs in the perioperative period during cardiac surgery, has been shown to be associated with increased morbidity and mortality. The management of perioperative hyperglycemia during coronary artery bypass graft surgery and all cardiac surgical procedures has been the focus of intensive study in recent years. This report will paper the pathophysiology responsible for the detrimental effects of perioperative hyperglycemia during cardiac surgery, show how continuous insulin infusions in the perioperative period have improved outcomes, and discuss the results of trials designed to determine what level of a glycemic control is necessary to achieve optimal clinical outcomes.

Postoperative Atrial Fibrillation: Year 2011 Review of Predictive and Preventative Factors of Atrial Fibrillation Post Cardiac Surgery

Background: Post cardiac surgery atrial fibrillation is common after cardiac surgery. Despite the advances in medical and surgical treatment, its incidence remains high and unchanged for decades. The aim of this review was to summarize studies published in 2011 on identifying factors, prevention strategies, treatment and effect of post operative atrial fibrillation (POAF) on the outcome after cardiac surgery. Methods: A review was performed on Medline, Embase and Chocrane on all of the English-language, peer-reviewed published clinical studies on POAF; studies investigating the mechanism of developing POAF, prevention, treatment and outcome were all included and analyzed. Case reports, studies on persistent/preoperative atrial fibrillation (AF), POAF after cardiac transplant, congenital cases and nonclinical studies were all excluded. We have also valuated these studies based on the type of the study, their originality, impact factor of the journal and their limitations. Results: Overall 62 studies were reviewed and analyzed; 26 on POAF predictive factors, 31 on preventative strategies and 6 on the outcome of POAF. Of these studies only two were original and the remaining were either performed in AF in general population (n=10) or had been studied and reported several times before in cardiac surgery (n=50). The average impact factor of the journals that POAF was published in was only 2.8 ranging between 0.5 and 14.5. Conclusion: Post cardiac surgery atrial fibrillation is a multi-factorial and complex condition. Cardiac surgery may be a risk factor for developing POAF in patients already susceptible to this condition and may not be a complication of cardiac surgery. Future studies should mainly focus on histological changes in the conductive tissue of atrium and related treatment strategies rather than predictive factors of POAF and more funding should be made available to study this condition from new and entirely different perspectives.

Effects of glycemic control on prevalence of diabetic frozen shoulder

BACKGROUND

There is controversy regarding the influence of glycemic control in diabetic patients with frozen shoulder. To determine the relationship between glycemic control and the prevalence of frozen shoulder in diabetic patients, we hypothesized that increased glycosylated hemoglobin A1c (HbA1c) levels would correlate with an increased prevalence of frozen shoulder.

METHODS

A retrospective analysis with statistical review of 201,513 diabetic patients enrolled in a regional health maintenance organization in 2007 was performed. Analysis included determining the relationship between the prevalence of frozen shoulder and the following factors: HbA1c level, type of diabetes treatment, duration of diabetes treatment, and presence of end-stage diabetic manifestations.

RESULTS

There were 1150 diabetic patients with a diagnosis of frozen shoulder. There was no significant relationship between HbA1c level and the prevalence of frozen shoulder. Insulin-dependent patients who used or did not use oral hypoglycemics were 1.93 times more likely than non-insulin-dependent diabetic patients to have frozen shoulder, and that rate increased to 1.96 times more likely when the results were adjusted for HbA1c level. Patients who were taking oral hypoglycemic drugs were 1.5 times more likely to develop frozen shoulder than those who did not use insulin or take oral hypoglycemic drugs. Duration of diabetes was also associated with the development of frozen shoulder, after controlling for insulin use (odds ratio: 1.85 for duration of more than ten years of use compared with less than five years of use). The prevalence of end-stage diabetic manifestations was increased in patients with frozen shoulder as compared with those without frozen shoulder (p < 0.0001).

CONCLUSION

There was no association found between HbA1c level and the prevalence of frozen shoulder in this diabetic population.

Preoperative hemoglobin A1c predicts atrial fibrillation after off-pump coronary bypass surgery

OBJECTIVE

Diabetes mellitus has been recognized as a risk factor for mortality and morbidity after coronary bypass grafting, but a significant association between diabetes mellitus and postoperative atrial fibrillation (AF) has not been found. Although a recent study demonstrated a potential link between preoperative hemoglobin A1c level and risk of postoperative AF, there has not been sufficient examination of this relationship. We aimed to investigate the association between preoperative hemoglobin A1c and AF after isolated off-pump coronary bypass grafting.

METHODS

Of 912 consecutive patients undergoing isolated coronary bypass surgery, 805 were retrospectively analyzed for AF after excluding the following 107 cases: emergency (n=81), chronic AF (n=18), and pacemaker rhythm (n=8). We performed a group analysis with hemoglobin A1c levels categorized into tertiles of the baseline distribution and a continuous analysis based on 1% increments in hemoglobin A1c levels. The cutoff points for the tertiles were as follows: lower, 3.8-5.6% (n=283); middle, 5.7-6.7% (n=282); upper, 6.8-11.4% (n=240).

RESULTS

AF occurred in 159 patients (19.8%) after surgery. The median value (25th-75th percentile) of preoperative hemoglobin A1c was significantly lower in patients who developed AF than in those who did not (5.8 (5.4-6.3) vs 6.1 (5.5-7.2), p=0.01). The incidence of postoperative AF was 28.3% (80/283) in the lower tertile, 17.4% (49/282) in the middle tertile, and 12.5% (30/240) in the upper tertile (p for trend=0.01). The unadjusted odds ratio (95% confidence interval) for the association between hemoglobin A1c and postoperative AF was 0.70 (0.61-0.83) per 1% increase and 0.42 (0.29-0.70) for the upper versus the lower tertile. This association persisted after adjustment for the univariate predictors (0.74 (0.60-0.92) per 1% increase; 0.54 (0.31-0.90) for upper vs lower tertile) and the known risk factors (0.78 (0.63-0.95) per 1% increase; 0.55 (0.35-0.88) for upper vs lower tertile). The area under the receiver operator characteristic curve (95% confidence interval) for preoperative hemoglobin A1c as a predictor of postoperative AF was 0.70 (0.65-0.75) (p=0.01).

CONCLUSIONS

Preoperative hemoglobin A1c independently predicts the occurrence of AF after isolated off-pump coronary bypass grafting.

Assessing inpatient glycemic control: what are the next steps?

Despite the emergence of glucometrics (i.e., systematic analysis of data on blood glucose levels of inpatients) as a subject of high interest, there remains a lack of standardization on how glucose parameters are measured and reported. This dilemma must be resolved before a national benchmarking process can be developed that will allow institutions to track and compare inpatient glucose control performance against established guidelines and that can also be supported by quality care organizations. In this article, we review some of the questions that need to be resolved through consensus and review of the evidence, and discuss some of the limitations in analyzing and reporting inpatient glucose data that must be addressed (or at least accepted as limitations) before hospitals can commit resources to gathering, compiling, and presenting inpatient glucose statistics as a health care quality measure. Standards must include consensus on which measures to report, the unit of analysis, definitions of targets for hyperglycemia treatment, a definition of hypoglycemia, determination of how data should be gathered (from chart review or from laboratory information systems), and which type of sample (blood or point of care) should be used for analysis of glycemic control. Hospitals and/or their representatives should be included in the discussion. For inpatient glucose control to remain a focus of interest, further dialogue and consensus on the topic are needed.

Prognostic significance of hemoglobin A1c level in patients hospitalized with coronary artery disease. A systematic review and meta-analysis

BACKGROUND

The prognostic value of hemoglobin A1c (HbA1c) in coronary artery disease (CAD) remains controversial. Herein, we conducted a systematic review to quantify the association between elevated HbA1c levels and all-cause mortality among patients hospitalized with CAD.

METHODS

A systematic search of electronic databases (PubMed, EMBASE, OVID, Web of Science, The Cochrane Library) for studies published from 1970 to May 2011 was performed. Cohort, case-control studies, and randomized controlled trials that examined the effect of HbA1c on all-cause mortality were included.

RESULTS

Twenty studies met final inclusion criteria (total n = 13, 224). From the pooled analyses, elevated HbA1c level was significantly associated with increased short-term (OR 2.32, 95% CI, 1.61 to 3.35) and long-term (OR 1.54, 95% CI, 1.23 to 1.94) mortality risk. Subgroup analyses suggested elevated HbA1c level predicted higher mortality risk in patients without diabetes (OR 1.84, 95% CI, 1.51 to 2.24). In contrast, in patients with diabetes, elevated HbA1c level was not associated with increased risk of mortality (OR 0.95, 95% CI, 0.70 to 1.28). In a risk-adjusted sensitivity analyses, elevated HbA1c was also associated with a significantly high risk of adjusted mortality in patients without diabetes (adjusted OR 1.49, 95% CI, 1.24 to 1.79), but had a borderline effect in patients with diabetes (adjusted OR 1.05, 95% CI, 1.00 to 1.11).

CONCLUSIONS

Our findings demonstrate that elevated HbA1c level is an independent risk factor for mortality in CAD patients without diabetes, but not in patients with established diabetes. Prospective studies should further investigate whether glycemic control might improve outcomes in CAD patients without previously diagnosed diabetes.

Impaired fasting glucose is associated with increased perioperative cardiovascular event rates in patients undergoing major non-cardiothoracic surgery

BACKGROUND

Diabetes mellitus (DM) is a well-established risk factor for perioperative cardiovascular morbidity and mortality in patients undergoing noncardiac surgery. However, the impact of preoperative glucose levels on perioperative cardiovascular outcomes in patients undergoing nonemergent, major noncardiothoracic surgery is unclear.

METHODS AND RESULTS

A total of 680 patients undergoing noncardiothoracic surgery were prospectively evaluated. Patients older than 18 years who underwent an elective, nonday case, open surgical procedure were enrolled. Electrocardiography and cardiac biomarkers were obtained 1 day before surgery, and on days 1, 3 and 7 after surgery. Preoperative risk factors and laboratory test results were measured and evaluated for their association with the occurrence of in-hospital perioperative cardiovascular events. Impaired fasting glucose (IFG) defined as fasting plasma glucose values of 100 to 125 mg/dl; DM was defined as fasting plasma glucose ≥ 126 mg/dl and/or plasma glucose ≥ 200 mg/dl or the current use of blood glucose-lowering medication, and glucose values below 100 mg/dl were considered normal. Plasma glucose levels were significantly higher in patients with perioperative cardiovascular events (n=80, 11.8%) in comparison to those without cardiovascular events (131 ± 42.5 vs 106.5 ± 37.5, p < 0.0001). Multivariate analysis revealed that patients with IFG and DM were at 2.1- and 6.4-fold increased risk of perioperative cardiovascular events, respectively. Every 10 mg/dl increase in preoperative plasma glucose levels was related to a 11% increase for adverse perioperative cardiovascular events.

CONCLUSIONS

Not only DM but also IFG is associated with increased perioperative cardiovascular event rates in patients undergoing noncardiothoracic surgery.

Differences in myocardial PTEN expression and Akt signalling in type 2 diabetic and nondiabetic patients undergoing coronary bypass surgery

OBJECTIVE

Patients with diabetes experience increased cardiovascular complications after cardiac surgery. Hyperglycaemia predicts increased mortality after myocardial infarction and may influence cardiovascular risk in humans. Impaired prosurvival phosphatase and tensin homologue on chromosome 10 (PTEN)-Akt signalling could be an important feature of the diabetic heart rendering it resistant to preconditioning. This study was designed to evaluate for differences and relationships of myocardial PTEN-Akt-related signalling and baseline glycaemic control marker in type 2 diabetic and nondiabetic patients undergoing coronary artery bypass surgery.

METHODS

Right atrial biopsies and coronary sinus blood were obtained from 18 type 2 diabetic and 18 nondiabetic patients intraoperatively. Expression and phosphorylation of Akt, endothelial nitric oxide synthase (eNOS), Bcl-2 and PTEN were evaluated by Western blot. Plasma 15-F(2t) -isoprostane concentrations were evaluated by liquid chromatography-mass spectrometry.

RESULTS

PTEN expression and 15-F(2t) -isoprostane concentrations were significantly higher in diabetic patients. Increased fasting blood glucose levels correlated with increased coronary sinus plasma 15-F(2t) -isoprostane concentrations. Increased cardiac 15-F(2t) -isoprostane generation was highly correlated with myocardial PTEN expression. Bcl-2 expression and eNOS phosphorylation were significantly lower in diabetic compared with nondiabetic patients. Akt phosphorylation tended to be lower in diabetic patients; however, this tendency failed to reach statistical significance.

CONCLUSION

The current results suggest that prosurvival PTEN-Akt signalling is impaired in the diseased diabetic myocardium. Hyperglycaemia and increased oxidative stress may contribute to this phenomenon. These findings strengthen the understanding of the underlying biologic mechanisms of cardiac injury in diabetic patients, which could facilitate development of new treatments to prevent cardiovascular complications in this high-risk population.

Preoperative heart rate variability predicts atrial fibrillation after coronary bypass grafting

BACKGROUND

The purpose of the present study was to investigate the association between preoperative heart rate variability and atrial fibrillation after off-pump coronary artery bypass graft surgery.

METHODS

Of 524 consecutive patients undergoing isolated coronary artery bypass surgery, 390 were retrospectively analyzed after excluding the following 134 cases: on-pump surgery (n = 6), emergency (n = 106), chronic atrial fibrillation (n = 17), and pacemaker rhythm (n = 5). The following time-domain factors of heart rate variability were calculated: standard deviation of all normal-to-normal QRS (SDNN) and square root of mean of sum of squares of differences between adjacent normal-to-normal QRS (RMSSD).

RESULTS

Atrial fibrillation occurred in 98 patients (25%) after surgery. Patients not having atrial fibrillation had significantly lower heart rate variability than did patients having atrial fibrillation, with median values of 91 versus 121 for SDNN and 19 versus 25 for RMSSD. Reduced heart rate variability was significantly associated with a lower risk of postoperative atrial fibrillation: the adjusted hazard ratio (95% confidence interval) was 0.29 (0.17 to 0.49) for SDNN 99 ms or less and 0.47 (0.30 to 0.74) for RMSSD 20 ms or less. The area under the receiver operating characteristic curves for SDNN and RMSSD as a predictor of postoperative atrial fibrillation was 0.764 and 0.696, respectively.

CONCLUSIONS

Reduced time-domain factors in preoperative 24-hour heart rate variability are independently associated with a lower risk of atrial fibrillation after off-pump coronary artery bypass surgery.

Glycemic control and infections in patients with diabetes undergoing noncardiac surgery

OBJECTIVE

Examine the relationship between perioperative glucose control and postoperative infections in a nationwide sample of diabetic patients undergoing a wide variety of surgical procedures.

SUMMARY OF BACKGROUND DATA

Perioperative glucose control has been linked to postoperative infections after selected surgical procedures.

METHODS

Retrospective analysis of surgical outcomes data from 1999 to 2004 on 55,408 patients with diabetes undergoing a variety of noncardiac operations contained in the Veterans Heath Administration National Surgical Quality Improvement Program database, supplemented with the Veterans Heath Administration Decision Support Services hemoglobin A1c (HbA(₁c)) and serum glucose data. Multivariate Poisson regression model of postoperative infection including demographics, comorbidities, functional status, preoperative laboratories, surgical data, and glucose control (diabetes medications, serum glucose, HbA(₁c), mean serum glucose within 24 hours after surgery).

RESULTS

The most common procedures were herniorrhaphy (10%), carotid endarterectomy (6.6%), and open colectomy (5.6%). Mean (SD) preoperative HbA1c concentration was 7.9% (2.3); 51% of patients had preoperative serum glucose concentrations more than 150 mg/dL; and 72% of patients had a mean 24 hour postoperative glucose concentration at least 150 mg/dL. The overall postoperative infection rate was 8.0%. Higher rates of postoperative infection were associated with mean 24 hour postoperative serum glucose concentrations of 150 to 250 mg/dL (incidence rate ratio 1.22, 95% confidence interval, 1.04-1.43; P = 0.01) and more than 250 mg/dL (incidence rate ratio: 1.43; 95% confidence interval, 1.19-1.71; P < 0.001). Preoperative HbA1c and glucose concentrations were not associated with increased infection rates.

CONCLUSIONS

In a large nationwide sample of diabetic patients undergoing a variety of noncardiac surgical procedures, glucose control in the first 24 hours after surgery was poor, and mean serum glucose concentrations of 150 mg/dL and higher during this time period were associated with increased rates of postoperative infectious complications.

[Postoperative wound infections. Pathophysiology, risk factors and preventive concepts]

Postoperative wound infections are the third most common type of nosocomial infection in German emergency hospitals after pneumonia and urinary infections. They are associated with increased morbidity and mortality, prolonged hospital stay and increased costs. The most important risk factors include the microbiological state of the skin surrounding the incision, delayed or premature prophylaxis with antibiotics, duration of surgery, emergency surgery, poorly controlled diabetes mellitus, malignant disease, smoking and advanced age. Anesthesiological measures to decrease the incidence of wound infections are maintaining normothermia, strict indications for allogenic blood transfusions and timely prophylaxis with antibiotics. Blood glucose concentrations should be kept in the range of 8.3-10 mmol/l (150-180 mg/dl) as lower values are associated with increased complications. Intraoperative and postoperative hyperoxia with 80% O(2) has not been shown to effectively decrease wound infections. The application of local anesthetics into the surgical wound in clinically relevant doses for postoperative analgesia does not impair wound healing.

Impact of chronic kidney disease on survival after amputation in individuals with diabetes

OBJECTIVE

To identify factors that influence survival after diabetes-related amputations.

RESEARCH DESIGN AND METHODS

We abstracted medical records of 1,043 hospitalized subjects with diabetes and a lower-extremity amputation from 1 January to 31 December 1993 in six metropolitan statistical areas in south Texas. We identified mortality in the 10-year period after amputation from death certificate data. Diabetes was verified using World Health Organization criteria. Amputations were identified by ICD-9-CM codes 84.11-84.18 and categorized as foot, below-knee amputation, and above-knee amputation and verified by reviewing medical records. We evaluated three levels of renal function: chronic kidney disease (CKD), hemodialysis, and no renal disease. We defined CKD based on a glomerular filtration rate<60 ml/min and hemodialysis from Current Procedural Terminology (CPT) codes (90921, 90925, 90935, and 90937). We used χ2 for trend and Cox regression analysis to evaluate risk factors for survival after amputation.

RESULTS

Patients with CKD and dialysis had more below-knee amputations and above-knee amputations than patients with no renal disease (P<0.01). Survival was significantly higher in patients with no renal impairment (P<0.01). The Cox regression indicated a 290% increase in hazard for death for dialysis treatment (hazard ratio [HR] 3.9, 95% CI 3.07-5.0) and a 46% increase for CKD (HR 1.46, 95% CI 1.21-1.77). Subjects with an above-knee amputation had a 167% increase in hazard (HR 2.67, 95% CI 2.14-3.34), and below-knee amputation patients had a 67% increase in hazard for death.

CONCLUSIONS

Survival after amputation is lower in diabetic patients with CKD, dialysis, and high-level amputations.

Perioperative management of ambulatory surgical patients with diabetes mellitus

PURPOSE OF REVIEW

Patients with diabetes frequently present for ambulatory surgery concomitant with the rise in incidence of the disease. This review will examine recent evidence on glucose control, the harmful effects of hyperglycemia, fluctuations of blood glucose, and hypoglycemia, as well as treatments and medications utilized for type 1 and type 2 diabetes mellitus. Based on this evidence, a strategy for perioperative decision making for the diabetic patient undergoing ambulatory surgery will be presented.

RECENT FINDINGS

New studies question the practice of intensive control of blood glucose in critically ill patients. Also, tight control of HbA1c levels in patients with type 2 diabetes may have associated cardiovascular risks. Glucose fluctuations and hypoglycemia may pose greater risks to patients than elevated glucose itself. New medications and insulin regimens make perioperative blood glucose control easier now than in the past.

SUMMARY

The ambulatory anesthesiologist, with a dedication to low-impact practices and emphasis on rapid recovery, provides an ideal environment of care for the patient with diabetes. This review will examine issues and concerns with management of the patient with diabetes undergoing ambulatory surgery and address them in a step-wise strategy for care, including recommendations for perioperative insulin administration.

Effect of skeletonization of the internal thoracic artery for coronary revascularization on the incidence of sternal wound infection

Use of the internal thoracic artery in coronary revascularization confers excellent benefit. We assessed the impact of skeletonization on the incidence of postoperative sternal wound infection in patients undergoing coronary artery bypass grafting. We also investigated whether there is an advantage in using this technique when harvesting both internal thoracic arteries in high-risk groups, such as diabetic patients. Skeletonization was associated with beneficial reduction in the odds ratio of sternal wound infection (odds ratio, 0.41; 95% confidence interval, 0.26 to 0.64). This effect was more evident when analyzing diabetic patients undergoing bilateral internal thoracic artery grafting (odds ratio, 0.19; 95% confidence interval, 0.10 to 0.34).

Cardiac surgery and acute kidney injury: emerging concepts

PURPOSE OF REVIEW

To review recent advances in understanding of the occurrence, pathophysiology, prophylaxis and treatment of cardiac surgery-associated acute kidney injury (AKI).

RECENT FINDINGS

New definitions and prompt diagnostic tools, enhanced risk stratification strategies, avoidance of nephrotoxins and procedure selection are all areas in which recent contributions to the literature have improved perioperative care for cardiac surgery patients. Although evidence continues to confirm the adverse effects of extreme hemodilution and transfusion as part of cardiac surgery, the previously believed advantages of tight perioperative glucose control for the kidney are being questioned in recent studies. Although very little evidence from randomized trials in cardiac surgery populations supports specific interventions to protect or prevent AKI, recent reports indicate reduced AKI associated with some procedural innovations, and the hope that promising findings for agents such as sodium bicarbonate that require further study may yield effective therapies.

SUMMARY

The vexing problem of AKI following cardiac surgery is common and unsolved. Clinical strategies that stress avoidance rather than treatment remain the mainstay of effective management of patients at high renal risk.

Long-term glucose control and risk of perioperative complications

BACKGROUND

The impact of long-term preoperative glucose control on short-term surgical complications is unclear. We investigated whether preoperative hemoglobin A1c (HA(1c)) levels correlated with the risk of postoperative complications.

METHODS

A database of 38,989 patients undergoing major surgical procedures from October 1996 to May 2007 was reviewed. Of these patients, 2,960 were diagnosed diabetic with a HA(1c) level within 30 days before their operation. National Surgical Quality Improvement Program (NSQIP) definitions were used in determining postoperative complications.

RESULTS

Of 36,039 nondiabetic patients, 5,095 experienced 1 or more complications (14.1%). In 2,960 diabetic patients, 780 diabetic patients had 1 or more complications (26.4%) (P <or=.001). Mortality was higher in diabetics than nondiabetics (4.2% vs 1%, respectively; P <.0001). There was no correlation between HA(1c) levels and risk of complication, type of complication, or death.

CONCLUSIONS

Although our data show an increased risk of surgical complications in diabetics, there was no detectable correlation between risk of complication and HA(1c) level. This suggests that poor long-term glucose control may not play a major role in determining short-term surgical morbidity.

Prevention of sternal wound infections after coronary artery bypass graft surgery with use of insulin drug therapy: a review of the literature

Diabetes is a disease that can increase the risks of developing cardiac problems, which can include coronary artery bypass graft surgery. These patients are at an increased risk of developing serious complications after this surgery, including deep sternal wound infections. In addition, nondiabetic patients may also develop this complication. Therefore, it is essential to monitor and maintain glucose levels after open heart surgery. This literature review discusses some of the studies in this area.

Perioperative and critical illness dysglycemia--controlling the iceberg

Patients with dysglycemia related to known or unrecognized diabetes, stress hyperglycemia, or hypoglycemia in the presence or absence of exogenous insulin routinely require care during the perioperative period or critical illness. Recent single and multicenter studies, a large multinational study, and three meta-analyses evaluated the safety of routine tight glycemic control (80-110 mg/dl) in critically ill adults. Results led to a call for more modest treatment goals (initiation of insulin at a blood glucose >180 mg/dl with a goal of approximately 150 mg/dl). In this symposium, an international group of multidisciplinary experts discusses the role of tight glycemic control, glucose measurement technique and its accuracy, glucose variability, hypoglycemia, and innovative methods to facilitate glucose homeostasis in this heterogeneous patient population.

Problems associated with glucose toxicity: Role of hyperglycemia-induced oxidative stress

Glucose homeostasis deficiency leads to a chronic increase in blood glucose concentration. In contrast to physiological glucose concentration, chronic superphysiological glucose concentration negatively affects a large number of organs and tissues. Glucose toxicity means a decrease in insulin secretion and an increase in insulin resistance due to chronic hyperglycemia. It is now generally accepted that glucose toxicity is involved in the worsening of diabetes by affecting the secretion of β-cells. Several mechanisms have been proposed to explain the adverse effects of hyperglycemia. It was found that persistent hyperglycemia caused the functional decline of neutrophils. Infection is thus the main problem resulting from glucose toxicity in the acute phase. In other words, continued hyperglycemia is a life-threatening risk factor, not only in the chronic but also the acute phase, and it becomes a risk factor for infection, particularly in the perioperative period.

Hyperglycemia during the immediate period after kidney transplantation

BACKGROUND AND OBJECTIVES

Hyperglycemia and new-onset diabetes occurs frequently after kidney transplantation. The stress of surgery and exposure to immunosuppression medications have metabolic effects and can cause or worsen preexisting hyperglycemia. To our knowledge, hyperglycemia in the immediate posttransplantation period has not been studied.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective, observational study to characterize the prevalence and assess the pharmacologic management of hyperglycemia in kidney transplant recipients who underwent transplantation at our center between June 1999 and December 2006. Data were abstracted from electronic and pharmacy databases.

RESULTS

The study cohort included 424 patients (mean age 51 yr; 58% men; 25% with pretransplantation diabetes). All patients with and 87% without pretransplantation diabetes had evidence of hyperglycemia (bedside glucose >or=200 mg/dl or physician-instituted insulin therapy), whereas the prevalence of hypoglycemia was low (4.5%). Hyperglycemia was sustained throughout hospitalization. All patients with and 66% without pretransplantation diabetes required insulin at hospital discharge. Patients with pretransplantation diabetes were treated primarily with short-acting insulin during the first 24 h after transplantation but were transitioned to long-acting insulin as the hospital stay progressed.

CONCLUSIONS

Investigators have historically attempted to identify hyperglycemia after hospital discharge. Our data indicate that a substantial number of patients without pretransplantation diabetes develop hyperglycemia and require insulin during the hospital phase of their care immediately after kidney transplantation. Prospective studies are needed to delineate factors that contribute to development of new-onset diabetes after transplantation among patients with transient hyperglycemia.

Elevated preoperative hemoglobin A1c level is associated with reduced long-term survival after coronary artery bypass surgery

BACKGROUND

The predictive role of hemoglobin A1c (HbA1c) on long-term outcomes after coronary artery bypass surgery has not been evaluated.

METHODS

Preoperative HbA1c levels were obtained in 3,201 patients undergoing primary, elective coronary artery bypass surgery at Emory Healthcare Hospitals from January 2002 to December 2006 and entered prospectively into a computerized database. Long-term survival status was determined by cross-referencing patient records with the Social Security Death Index. Log-rank (unadjusted) and Cox proportional hazards regression models (adjusted) were employed to determine whether HbA1c and diabetes mellitus were independent risk factors for reduced long-term survival, adjusted for 29 covariates. Hazard ratios for each unit increase in continuous HbA1c were calculated.

RESULTS

Patients with HbA1c of 7% or greater had lower unadjusted 5-year survival compared with patients with HbA1c less than 7% (p = 0.001). Similarly, patients with diabetes mellitus had lower unadjusted 5-year survival compared with patients without diabetes (p < 0.001). After multivariable adjustment, higher HbA1c (measured as a continuous variable) was associated with reduced long-term survival for each unit increase in HbA1c (hazard ratio 1.15, p < 0.001), but preoperative diagnosis of diabetes was not associated with reduced long-term survival after coronary artery bypass surgery (p = 0.41). Other multivariable predictors of reduced long-term survival included age, cerebrovascular disease, elevated serum creatinine, renal insufficiency, congestive heart failure, previous myocardial infarction, chronic lung disease, and peripheral vascular disease.

CONCLUSIONS

Poor preoperative glycemic control, as measured by an elevated HbA1c, is associated with reduced long-term survival after coronary artery bypass surgery. Optimizing glucose control in these patients may improve long-term survival.