The diabetic disadvantage: historical outcomes measures in diabetic patients undergoing cardiac surgery -- the pre-intravenous insulin era

Immunoglobulin-Mediated Cardiac Protection From Ischemia/Reperfusion Injury in Diabetic Rats Is Associated With Endothelial Nitric Oxide Synthase/Glucose Transporter-4 Signaling Pathway

ABSTRACT

The role of intravenous immunoglobulin in protecting the diabetic heart from ischemia/reperfusion (I/R) injury is unclear. Hearts isolated from adult diabetic and nondiabetic Wistar rats (n = 8 per group) were treated with intravenous immunoglobulin (IVIG) either 2 hours before euthanasia, before ischemia, or at reperfusion. Hemodynamic data were acquired using the Isoheart software version 1.524-S. Ischemia/reperfusion (I/R) injury was evaluated by 2,3,5-triphenyltetrazolium chloride staining and troponin T levels. The levels of apoptosis markers, caspases-3/8, antioxidant enzymes, superoxide dismutase and catalase, glucose transporters, GLUT-1 and GLUT-4, phosphorylated ERK1/2, and phosphorylated eNOS were estimated by Western blotting. Proinflammatory and anti-inflammatory cytokine levels were evaluated using enzyme-linked immunosorbent assays. Intravenous immunoglobulin administration abolished the effects of I/R injury in hearts subjected to hyperglycemia when infused at reperfusion, before ischemia, or at reperfusion in 4-week diabetic rat hearts and only at reperfusion in 6-week diabetic rat hearts. IVIG infusion resulted in a significant (P < 0.05) recovery of cardiac hemodynamics and decreased infarct size. IVIG also reduced the levels of troponin T, apoptotic enzymes, and proinflammatory cytokines. IVIG significantly (P < 0.05) increased the levels of anti-inflammatory cytokines, antioxidant enzymes, GLUT-4, and phosphorylated eNOS. Intravenous immunoglobulin protected the hearts from I/R injury if infused at reperfusion in the presence of hyperglycemia, in 4- and 6-week diabetic rat hearts, and when infused before ischemia in 4-week diabetic rat hearts. IVIG exerts its cardioprotective effects associated with the upregulated phosphorylated eNOS/GLUT-4 pathway.

Nitric Oxide/Glucose Transporter Type 4 Pathway Mediates Cardioprotection against Ischemia/Reperfusion Injury under Hyperglycemic and Diabetic Conditions in Rats

INTRODUCTION

The comorbidities of ischemic heart disease (IHD) and diabetes mellitus (DM) compromise the protection of the diabetic heart from ischemia/reperfusion (I/R) injury. We hypothesized that manipulation of reperfusion injury salvage kinase (RISK) and survivor activating factor enhancement (SAFE) pathways might protect the diabetic heart, and intervention of these pathways could be a new avenue for potentially protecting the diabetic heart.

METHODS

All hearts were subjected to 30-min ischemia and 30-min reperfusion. During reperfusion, hearts were exposed to molecules proven to protect the heart from I/R injury. The hemodynamic data were collected using suitable software. The infarct size, troponin T levels, and protein levels in hearts were evaluated.

RESULTS

Both cyclosporine-A and nitric oxide donor (SNAP) infusion at reperfusion protected 4-week diabetic hearts from I/R injury. However, 6-week diabetic hearts were protected only by SNAP, but not cyclosporin-A. These treatments significantly (p < 0.05) improved cardiac hemodynamics and decreased infarct size.

CONCLUSIONS

The administration of SNAP to diabetic hearts protected both 4- and 6-week diabetic hearts; however, cyclosporine-A protected only the 4-week diabetic hearts. The eNOS/GLUT-4 pathway executed the SNAP-mediated cardioprotection.

Percutaneous Left Atrial Appendage Closure Among Patients With Diabetes (Insights from a National Database)

Atrial fibrillation is a major risk factor for stroke. Left atrial appendage closure (LAAC) has emerged as an alternative to anticoagulation for patients with high risk of bleeding. Diabetes mellitus (DM) is associated with adverse events after cardiac procedures. We sought to compare procedural and hospital outcomes in patients who underwent LAAC with and without DM. The Nationwide Inpatient Database was queried for patients with atrial fibrillation who underwent LAAC between January 1, 2016, and December 31, 2019. The primary outcome was all adverse events that included in-hospital death, acute myocardial infarction, cardiac arrest, stroke, pericardial effusion, pericardial tamponade, pericardiocentesis, pericardial window, and postprocedural hemorrhage requiring blood transfusion. Analysis included 62,220 patients who underwent LAAC from 2016 to 2019; 34.9% of patients had DM. There was a slight increase in the percentage of patients who underwent LAAC who had DM during the study period, from 29.92% to 34.93%. In unadjusted and adjusted analysis, there was no significant difference in all adverse events between patients with and without DM who underwent LAAC (9.18% vs 8.77%, respectively, adjusted p = 0.63), and no difference in length of stay. Patients with DM have higher risk of acute kidney injury (3.75 vs 1.96%, p <0.001). This nationwide retrospective study demonstrates that DM is not associated with an increase in adverse event rates in patients who underwent LAAC.

Renin-Angiotensin System Antagonism Protects the Diabetic Heart from Ischemia/Reperfusion Injury in Variable Hyperglycemia Duration Settings by a Glucose Transporter Type 4-Mediated Pathway

BACKGROUND

Diabetes mellitus (DM) is a risk factor for cardiovascular diseases, specifically, the ischemic heart diseases (IHD). The renin-angiotensin system (RAS) affects the heart directly and indirectly. However, its role in the protection of the heart against I/R injury is not completely understood. The aim of the current study was to evaluate the efficacy of the angiotensin-converting enzyme (ACE) inhibitor and Angiotensin II receptor (AT1R) blocker or a combination thereof in protection of the heart from I/R injury.

METHODS

Hearts isolated from adult male Wistar rats (n = 8) were subjected to high glucose levels; acute hyperglycemia or streptozotocin (STZ)-induced diabetes were used in this study. Hearts were subjected to I/R injury, treated with Captopril, an ACE inhibitor; Losartan, an AT1R antagonist; or a combination thereof. Hemodynamics data were measured using a suitable software for that purpose. Additionally, infarct size was evaluated using 2,3,5-Triphenyltetrazolium chloride (TTC) staining. The levels of apoptosis markers (caspase-3 and -8), antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), nitric oxide synthase (eNOS), and glucose transporter type 4 (GLUT-4) protein levels were evaluated by Western blotting. Pro-inflammatory and anti-inflammatory cytokines levels were evaluated by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Captopril and Losartan alone or in combination abolished the effect of I/R injury in hearts subjected to acute hyperglycemia or STZ-induced diabetes. There was a significant (p < 0.05) recovery in hemodynamics, infarct size, and apoptosis markers following the treatment with Captopril, Losartan, or their combination. Treatment with Captopril, Losartan, or their combination significantly (p < 0.05) reduced pro-inflammatory cytokines and increased GLUT-4 protein levels.

CONCLUSIONS

The blockade of the RAS system protected the diabetic heart from I/R injury. This protection followed a pathway that utilizes GLUT-4 to decrease the apoptosis markers, pro-inflammatory cytokines, and to increase the anti-inflammatory cytokines. This protection seems to employ a pathway which is not involving ERK1/2 and eNOS.

Anti-inflammatory and Anti-endoplasmic reticulum stress Effects of catalpol Against myocardial ischemia-reperfusion injury in streptozotocin-induced diabetic rats

The current study was designed to investigate the effects and the mechanism of catalpol on myocardial ischemia-reperfusion (MI/R) injury in a diabetic rat model. Male Sprague-Dawley rats were divided into DM + sham, DM +I/R, and DM +I/R + C groups and diabetes was induced using single injections of streptozotocin (STZ; 70 mg/kg; i.p). After confirming the induction of diabetes, rats were administered physiological saline and catalpol (10 mg/kg; i.p.) daily for 28 days. Subsequently, rats were subjected to left anterior descending (LAD) coronary artery occlusion for 30 min followed by reperfusion for 2 h. Haemodynamic parameters were recorded throughout surgery, and following sacrifice, hearts were isolated for biochemical, histopathological, and molecular analyses. Catalpol treatment significantly ameliorated MI/R injury by improving cardiac function, normalizing myocardial enzyme activities and markers of oxidative stress, and by maintaining myocardial architecture. Furthermore, expression levels of the inflammatory cytokines TNF-α and IL-6 were decreased in biochemical and immunohistochemical studies. Additionally, the cardioprotective effects of catalpol were partly related to reductions in myocardial endoplasmic reticulum stress (ERS). In conclusion, catalpol exerts cardioprotective effects in diabetic rats by attenuating inflammation and inhibiting ERS.

Percutaneous closure of the left atrial appendage in patients with diabetes mellitus

BACKGROUND

Left atrial appendage closure is a preventive treatment of atrial fibrillation-related thrombo-embolism. Patients with diabetes mellitus have increased risk for a negative outcome in percutaneous cardiac interventions. We assessed whether percutaneous left atrial appendage closure is safe and effective in patients with diabetes mellitus.

METHODS

We included 78 patients (mean age of 74.4 ± 8.3 years) with indication for left atrial appendage closure in an open-label observational single-centre study.

RESULTS

Patients with diabetes mellitus ( n = 31) were at higher thrombo-embolic and bleeding risk (CHA₂DS₂-VASc: 4.5 ± 0.9, HAS-BLED: 4.7 ± 0.7) compared to patients without diabetes mellitus ( n = 47, CHA₂DS₂-VASc: 3.5 ± 1.0, HAS-BLED: 4.1 ± 0.8; p < 0.001 for both). Pre- and periprocedural risk was elevated in patients with diabetes mellitus (Euro II-Score: 6.6 ± 3.7 vs 3.9 ± 1.9, p < 0.01; Society of Thoracic Surgeons (STS)-Score: 4.0 ± 2.5 vs 2.6 ± 1.2, p < 0.01). Procedural success was similar. Periprocedural major adverse cardiac and cerebrovascular events occurred in one patient from the control group (2.1%), whereas patients with diabetes mellitus had no events ( p = 0.672). Follow-up of 6 months revealed no bleeding complication in both groups. No stroke occurred in follow-up, and left atrial appendage flow velocity reduction (55.6 ± 38.6 vs 51.4 ± 19.1 cm/s, p = 0.474) and rate of postinterventional leakage in the left atrial appendage were comparable (0% vs 2.1%, p = 0.672).

CONCLUSION

Despite patients with diabetes mellitus are high-risk patients, the outcome of percutaneous left atrial appendage closure is similar to patients without diabetes mellitus.

European Association for Cardio-Thoracic Surgery expert consensus statement on the prevention and management of mediastinitis

Mediastinitis continues to be an important and life-threatening complication after median sternotomy despite advances in prevention and treatment strategies, with an incidence of 0.25-5%. It can also occur as extension of infection from adjacent structures such as the oesophagus, airways and lungs, or as descending necrotizing infection from the head and neck. In addition, there is a chronic form of 'chronic fibrosing mediastinitis' usually caused by granulomatous infections. In this expert consensus, the evidence for strategies for treatment and prevention of mediatinitis is reviewed in detail aiming at reducing the incidence and optimizing the management of this serious condition.

Protective effect of mangiferin on myocardial ischemia-reperfusion injury in streptozotocin-induced diabetic rats: role of AGE-RAGE/MAPK pathways

Hyperglycemia induced advanced glycation end products-receptor for advanced glycation end products (AGE-RAGE) activation is thought to involve in the development of cardiovascular disease in diabetics. Activation of AGE-RAGE axis results in the oxidative stress and inflammation. Mangiferin is found in the bark of mango tree and is known to treat diseases owing to its various biological activities. Thus, this study was designed to evaluate the effect of mangiferin in ischemia-reperfusion (IR) induced myocardial injury in diabetic rats. A single injection of STZ (70 mg/kg; i.p.) was injected to male albino Wistar rats to induce diabetes. After confirmation of diabetes, rats were administered vehicle (2 ml/kg; i.p.) and mangiferin (40 mg/kg; i.p.) for 28 days. On 28^th day, left anterior descending coronary artery was ligated for 45 min and then reperfused for 60 min. Mangiferin treatment significantly improved cardiac function, restored antioxidant status, reduced inflammation, apoptosis and maintained myocardial architecture. Furthermore, mangiferin significantly inhibited the activation of AGE-RAGE axis, c-Jun N-terminal kinase (JNK) and p38 and increased the expression of extracellular regulated kinase 1/2 (ERK1/2) in the myocardium. Thus, mangiferin attenuated IR injury in diabetic rats by modulation of AGE-RAGE/MAPK pathways which further prevented oxidative stress, inflammation and apoptosis in the myocardium.

Effect of Combination of Angiotensin-Converting Enzyme Inhibitors and Vitamin D Receptor Activators on Cardiac Oxidative Stress in Diabetic Rats

BACKGROUND

The principle mediator of diabetic myocardial injury is oxidative stress. The aim was to compare the effect of monotherapy with enalapril, angiotensin-converting enzyme inhibitor and paricalcitol (vitamin D receptor activator), to the combined therapy with both drugs on the cardiac oxidant-antioxidant balance in the type 2 diabetic rats.

MATERIALS AND METHODS

A total of 50 male Sprague-Dawley rats were divided into 5 groups, namely the normal control and diabetic, vehicle, enalapril, paricalcitol and paricalcitol and enalapril-treated groups. Enalapril was given at a dose of (25mg/L) in drinking water once daily and paricalcitol was given intraperitoneally (0.8μg/kg/3 × week) for 3 months. Glycemic status, cardiac oxidant-antioxidant parameters and histologic examination were determined.

RESULTS

Paricalcitol and combined treatment significantly (P < 0.01) reduced the level of fasting, postprandial blood glucose, homeostatic model assessment-insulin resistance, cardiac malondialdehyde and nitric oxide. Moreover, they significantly (P < 0.01) increased the levels of insulin and c-peptide compared to diabetic control rats. Combined treatment significantly (P < 0.01) raised the level of glutathione, glutathione S-transferase and catalase more than monotherapy.

CONCLUSION

The combination of angiotensin-converting enzyme inhibitors and vitamin D receptor activators has a superior effect on reducing cardiac oxidative stress by raising antioxidant activity than monotherapy in diabetic rats.

The effect of levosimendan on myocardial ischemia-reperfusion injury in streptozotocin-induced diabetic rats

Objective

Ischemia/reperfusion (I/R) injury is an important cause of myocardial damage by means of oxidative, inflammatory, and apoptotic mechanisms. The aim of the present study was to examine the potential cardio protective effects of levosimendan in a diabetic rat model of myocardial I/R injury.

Methods

A total of 18 streptozotocin-induced diabetic Wistar Albino rats (55 mg/kg) were randomly divided into three equal groups as follows: the diabetic I/R group (DIR) in which myocardial I/R was induced following left thoracotomy, by ligating the left anterior descending coronary artery for 60 min, followed by 2 h of reperfusion; the diabetic I/R levosimendan group (DIRL), which underwent I/R by the same method while taking levosimendan intraperitoneal 12 µg kg⁻¹; and the diabetic control group (DC) which underwent sham operations without tightening of the coronary sutures. As a control group (C), six healthy age-matched Wistar Albino rats underwent sham operations similar to the DC group. Two hours after the operation, the rats were sacrificed and the myocardial tissue samples were examined by light microscopy for evidence of myonecrosis and inflammatory cell infiltration.

Results

Myonecrosis findings were significantly different among groups (p=0.008). Myonecrosis was more pronounced in the DIR group compared with the C, DC, and DIRL groups (p=0.001, p=0.007 and p=0.037, respectively). Similarly, the degree of inflammatory cell infiltration showed significant difference among groups (p<0.0001). Compared with C, DC, and DIRL groups, the inflammatory cell infiltration was significantly higher among the DIR group (p<0.0001, p<0.0001, and p=0.020, respectively). Also, myocardial tissue edema was significantly different among groups (p=0.006). The light microscopic myocardial tissue edema levels were significantly higher in the DIR group than the C, DC, and DIRL groups (p=0.001, p=0.037, and p=0.014, respectively).

Conclusion

Taken together, our data indicate that levosimendan may be helpful in reducing myocardial necrosis, myocardial inflammation, and myocardial tissue edema resulting from ischemia–reperfusion injury.

Deep sternal wound infection after cardiac surgery: Evidences and controversies

Despite many advances in prevention and perioperative care, deep sternal wound infection (DSWI) remains a pressing concern in cardiac surgery, with a still relevant incidence and with a considerable impact on in-hospital mortality and also on mid- and long-term survival. The permanent high impact of this complication is partially related to the increasing proportion of patients at high-risk for infection, as well as to the many patient and surgical risk factors involved in the pathogenesis of DSWI. The prophylactic antibiotic therapy is one of the most important tools in the prevention of DSWI. However, the choice of antibiotic, the dose, the duration, the adequate levels in serum and tissue, and the timing of antimicrobial prophylaxis are still controversial. The treatment of DSWI ranges from surgical revision with primary closure to surgical revision with open dressings or closed irrigation, from reconstruction with soft tissue flaps to negative pressure wound therapy (NPWT). However, to date, there have been no accepted recommendations regarding the best management of DSWI. Emerging evidence in the literature has validated the efficacy and safety of NPWT either as a single-line therapy, or as a “bridge” prior to final surgical closure. In conclusion, the careful control of patient and surgical risk factors - when possible, the proper antimicrobial prophylaxis, and the choice of validated techniques of treatment could contribute to keep DSWIs at a minimal rate.

Phosphatase and tensin homolog-induced putative kinase 1 and Parkin in diabetic heart: Role of mitophagy

Diabetes is an independent risk factor for cardiovascular morbidity and mortality. Diabetes-associated cardiac pathophysiology is recognized to be due to reasons including metabolic consequences on the myocardium. The heart is a highly energy-demanding tissue, with mitochondria supplying over 90% of adenosine triphosphate. The involvement of mitochondrial dysfunction in diabetes-related cardiac pathogenesis has been studied. Phosphatase and tensin homolog-induced putative kinase 1 (PINK1) and Parkin, initially identified to be associated with the pathogenesis of a familiar form of Parkinson's disease, have recently been recognized to play a critical role in mediating cardiomyocytes’ adaption to stresses. Extensive studies have suggested PINK1 and Parkin as key regulators of mitophagy. In the present review article, we will first summarize the new findings on PINK1/Parkin acting in cardioprotection, and then discuss the potential role of PINK1/Parkin in diabetic heart by mediating mitophagy.

An interdepartmental collaboration to improve preoperative glycemic control

BACKGROUND

The Centers for Disease Control and Prevention estimates that 25.8 million adults in the United States have diabetes, and these patients experience higher rates of morbidity and mortality postoperatively than patients without diabetes. While several professional organizations have recommended tight glycemic control perioperatively, the data regarding preoperative glycemic control is only emerging. The hemoglobin A1c level, which reflects long-term glycemic control, has been shown to correlate with postoperative outcomes including length of stay, infections, and mortality. This relationship has implications for the preoperative surgical management of patients with diabetes.

OBJECTIVES

Implemented in 2009, our interdepartmental initiative was designed to improve glycemic control within 5 to 7 days before surgery with a blood glucose target of 100 of 199 mg/dL the morning of surgery. An endocrinologist and a certified diabetes educator evaluate same-day urgent referrals from the anesthesia preoperative clinic, targeting high-risk patients with an HbA1c value of ≥ 9%, a random blood glucose level of ≥ 300 mg/dL, or a fasting blood glucose level of ≥ 240 mg/dL. Our team then creates an individualized preoperative treatment plan based on the patient's prior insulin regimen and diabetes self-management skills. Verbal and written instructions for insulin self-titration and guidance for insulin dose changes in preparation for a fasting state are included.

DISCUSSION

: With this interdepartmental collaboration, as part of a larger institutional initiative, we hope to improve short- and long-term outcomes for surgical patients with uncontrolled diabetes, as well as improve costs and utilization of health care resources in our institution. Our glycemic control committee, which follows bimonthly metrics, including 90-day readmission rates for surgical patients, has noted a decline from 7.9% in 2009 to 4.5% in the 2012-2013 fiscal year. Our aggressive preoperative and postoperative blood glucose management has been a significant factor in this improvement.

Safety and efficacy of percutaneous mitral valve repair using the MitraClip® system in patients with diabetes mellitus

BACKGROUND

Patients with diabetes mellitus show a negative outcome in percutaneous coronary intervention, aortic valve replacement and cardiac surgery. The impact of diabetes on patients undergoing treatment of severe mitral regurgitation (MR) using the MitraClip system is not known. We therefore sought to assess whether percutaneous mitral valve repair with the MitraClip system is safe and effective in patients with diabetes mellitus.

METHODS AND RESULTS

We included 58 patients with severe and moderate-to-severe MR in an open-label observational single-center study. Ninteen patients were under oral medication or insulin therapy for type II diabetes mellitus. MitraClip devices were successfully implanted in all patients with diabetes and in 97.4% (n = 38) of patients without diabetes (p = 0.672). Periprocedural major cardiac adverse and cerebrovascular events (MACCE) occurred in 5.1% (n = 2) of patients without diabetes whereas patients with diabetes did not show any MACCE (p = 0.448). 30-day mortality was 1.7% (n = 1) with no case of death in the diabetes group. Short-term follow up of three months showed a significant improvement of NYHA class and quality of life evaluated by the Minnesota Living with Heart Failure Questionnaire in both groups, with no changes in the 6-minute walk test.

CONCLUSIONS

Mitral valve repair with the MitraClip system is safe and effective in patients with type II diabetes mellitus.

TRIAL REGISTRATION

MitraClip Registry NCT02033811.

Impact of diabetes on mortality and complications after coronary artery by-pass graft operation in patients with left main coronary artery disease

PURPOSE

Left main disease (LMD) is a severe form of coronary artery disease (CAD). Fifty percent of patients with LMD treated conservatively die within 3-5 years of diagnosis. The aim of the study was to assess the influence of type 2 diabetes on early and late (2-year) prognosis and the risk of complications after coronary artery by-pass graft (CABG) surgery in patients with LMD.

MATERIAL/METHODS

We enrolled 257 patients diagnosed with LMD. 169 (67%) underwent CABG, 19 (8%) percutaneous coronary intervention (PCI) without left main stem protection. 30 (12%) patients had CABG previously. Patients treated with CABG were divided into two groups - with and without diabetes. There were 43 (25.4%) patients with diabetes and 126 (74.6%) without diabetes.

RESULTS

We observed more complications with wound healing (40.5% vs. 12.8%, p<0.001) and sternal dehiscence (23.8% vs. 4.0%, p<0.001) after CABG in patients with diabetes. There were no differences in 7-day, 30-day, 3-month and 1-year mortality. 2-Year mortality was also similar in both groups (11.6% vs. 11.1%, p=0.928). Patients with diabetes were more frequently hospitalized due to other reasons than angina (39.5% vs. 20.6%, p=0.014).

CONCLUSIONS

Patients with diabetes and LMD had more often complications with wound healing and sternal dehiscence after CABG than patients without diabetes. Type 2 diabetes did not influence early and late mortality in patients with LMD treated with cardiac surgery, but the presence of diabetes was associated with more frequent hospitalizations.

Diabetes and stress hyperglycemia in the intensive care unit: outcomes after cardiac surgery

BACKGROUND

Hyperglycemia is common in the post-cardiac surgery population and has been associated with increased mortality rates, surgical length of stay, and infection rates. Although hospitalized patients with diabetes are known to have more complications, recent studies in various hospital settings have reported worse outcomes in patients with stress hyperglycemia than in those with diabetes.

AIM

The primary objective of this study was to analyze 30- and 90-day mortality rates in post-cardiac surgery patients with stress hyperglycemia and diabetes who were managed to achieve similar moderate blood glucose goals using the University of Michigan Hospital (Ann Arbor, MI) insulin protocol between 2005 and 2008. The secondary outcomes were rates of postoperative complications, including hypoglycemia.

METHODS

A standardized glucose management program was followed to treat all patients in the cardiac intensive care unit, with a blood glucose goal of 100 to 140 mg/dL. Data from 1973 patients with either diabetes or stress hyperglycemia were analyzed to identify associations between mean postoperative blood glucose levels and mortality, incidence of hypoglycemia, and complication rates.

RESULTS

Mortality rates did not differ between patients with diabetes and stress hyperglycemia (3.4 and 2.3%; P = 0.2). Rates of severe hypoglycemia were low (1%) for both groups and were not associated with an increase in mortality (P = 0.95). Other complication rates were similar between patients with diabetes and stress hyperglycemia.

CONCLUSION

Maintaining a blood glucose range between 100 to 140 mg/dL in post-cardiac surgery patients was associated with a low mortality rate, low risk of hypoglycemia, and with complications rates that were similar in patients with diabetes and stress hyperglycemia.

Oxidative stress and myocardial injury in the diabetic heart

Reactive oxygen or nitrogen species play an integral role in both myocardial injury and repair. This dichotomy is differentiated at the level of species type, amount and duration of free radical generated. Homeostatic mechanisms designed to prevent free radical generation in the first instance, scavenge, or enzymatically convert them to less toxic forms and water, playing crucial roles in the maintenance of cellular structure and function. The outcome between functional recovery and dysfunction is dependent upon the inherent ability of these homeostatic antioxidant defences to withstand acute free radical generation, in the order of seconds to minutes. Alternatively, pre-existent antioxidant capacity (from intracellular and extracellular sources) may regulate the degree of free radical generation. This converts reactive oxygen and nitrogen species to the role of second messenger involved in cell signalling. The adaptive capacity of the cell is altered by the balance between death or survival signal converging at the level of the mitochondria, with distinct pathophysiological consequences that extends the period of injury from hours to days and weeks. Hyperglycaemia, hyperlipidaemia and insulin resistance enhance oxidative stress in the diabetic myocardium that cannot adapt to ischaemia-reperfusion. Altered glucose flux, mitochondrial derangements and nitric oxide synthase uncoupling in the presence of decreased antioxidant defence and impaired prosurvival cell signalling may render the diabetic myocardium more vulnerable to injury, remodelling and heart failure.

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.

In the critically ill patient, diabetes predicts mortality independent of statin therapy but is not associated with acute lung injury: a cohort study

OBJECTIVES

Patients with diabetes mellitus form 23%-30% of published cohorts of critically ill patients. Conflicting published evidence links diabetes mellitus to both higher and lower mortality. Other cohort studies suggest that diabetes mellitus protects against acute lung injury. We hypothesized that diabetes mellitus is an independent risk factor for mortality. We further hypothesized that diabetes mellitus is a risk factor for cardiac overload and not for acute lung injury.

DESIGN

Retrospective cohort study.

SETTING

The intensive care unit of a tertiary referral hospital.

PATIENTS

From November 1, 2004, to October 1, 2007, a cohort of patients admitted ≥48 hrs to the intensive care unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 2,013 patients, 317 had diabetes mellitus. Ninety-day mortality was higher in the diabetes mellitus patients compared to patients without diabetes mellitus (hazard ratio 1.53, 95% confidence interval 1.29-1.80). This association strengthened after adjusting for confounders and for medication (hazard ratio 1.53, 95% confidence interval 1.07-2.17).We found no association between diabetes mellitus and acute lung injury (relative risk ratio 1.01, 95% confidence interval 0.78-1.32; adjusted relative risk ratio 0.99, 95% confidence interval 0.75-1.31), but diabetes mellitus was a risk factor for cardiac overload (relative risk ratio 1.91, 95% confidence interval 1.30-2.81; adjusted relative risk ratio 1.45, 95% confidence interval 0.97-2.18). Statins were associated with both a reduced risk of mortality (hazard ratio 0.74, 95% confidence interval 0.63-0.87; adjusted hazard ratio 0.53, 95% confidence interval 0.44-0.64) and a decreased risk of developing acute lung injury (relative risk ratio 0.71, 95% confidence interval 0.56-0.89; adjusted relative risk ratio 0.61, 95% confidence interval 0.47-0.79).

CONCLUSIONS

Diabetes mellitus is an independent risk factor for mortality in critically ill patients and failure to adjust for statins underestimates the size of this association. Diabetes mellitus is not associated with acute lung injury but is associated with cardiac overload. A diagnosis of cardiac overload excludes a diagnosis of acute lung injury. Investigators who do not account for cardiac overload as a competing alternative outcome may therefore falsely conclude that diabetes mellitus protects from acute lung injury.

The impact of comorbid [corrected] conditions on critical illness

OBJECTIVE

To review the current knowledge of common comorbidities in the intensive care unit, including diabetes mellitus, chronic obstructive pulmonary disease, cancer, end-stage renal disease, end-stage liver disease, HIV infection, and obesity, with specific attention to epidemiology, contribution to diseases and outcomes, and the impact on treatments in these patients.

DATA SOURCE

Review of the relevant medical literature for specific common comorbidities in the critically ill.

RESULTS

Critically ill patients are admitted to the intensive care unit for various reasons, and often the admission diagnosis is accompanied by a chronic comorbidity. Chronic comorbid conditions commonly seen in critically ill patients may influence the decision to provide intensive care unit care, decisions regarding types and intensity of intensive care unit treatment options, and outcomes. The presence of comorbid conditions may predispose patients to specific complications or forms of organ dysfunction. The impact of specific comorbidities varies among critically ill medical, surgical, and other populations, and outcomes associated with certain comorbidities have changed over time. Specifically, outcomes for patients with cancer and HIV have improved, likely related to advances in therapy. Overall, the negative impact of chronic comorbidity on survival in critical illness may be primarily influenced by the degree of organ dysfunction or the cumulative severity of multiple comorbidities.

CONCLUSION

Chronic comorbid conditions are common in critically ill patients. Both the acute illness and the chronic conditions influence prognosis and optimal care delivery for these patients, particularly for adverse outcomes and complications influenced by comorbidities. Further work is needed to fully determine the individual and combined impact of chronic comorbidities on intensive care unit outcomes.

The cellular and molecular origin of reactive oxygen species generation during myocardial ischemia and reperfusion

Myocardial ischemia-reperfusion injury is an important cause of impaired heart function in the early postoperative period subsequent to cardiac surgery. Reactive oxygen species (ROS) generation increases during both ischemia and reperfusion and it plays a central role in the pathophysiology of intraoperative myocardial injury. Unfortunately, the cellular source of these ROS during ischemia and reperfusion is often poorly defined. Similarly, individual ROS members tend to be grouped together as free radicals with a uniform reactivity towards biomolecules and with deleterious effects collectively ascribed under the vague umbrella of oxidative stress. This review aims to clarify the identity, origin, and progression of ROS during myocardial ischemia and reperfusion. Additionally, this review aims to describe the biochemical reactions and cellular processes that are initiated by specific ROS that work in concert to ultimately yield the clinical manifestations of myocardial ischemia-reperfusion. Lastly, this review provides an overview of several key cardioprotective strategies that target myocardial ischemia-reperfusion injury from the perspective of ROS generation. This overview is illustrated with example clinical studies that have attempted to translate these strategies to reduce the severity of ischemia-reperfusion injury during coronary artery bypass grafting surgery.

Special considerations for the diabetic patient in the ICU; targets for treatment and risks of hypoglycaemia

Due to the diabetes pandemic the number of diabetic patients admitted to the intensive care unit (ICU) increases. Diabetic patients admitted to the ICU are more vulnerable for developing complications as compared to non-diabetic patients, but this does not directly translate into higher mortality rates. However, mortality might differ per admission diagnosis. Hyperglycaemia is common in diabetic as well as non-diabetic critically ill patients, but probably chronic hyperglycaemia is pathophysiologically different from acute hyperglycaemia. As opposed to non-diabetic patients, there is discussion about the association between hyperglycaemia and mortality in diabetic patients. They do not seem to benefit from strict glycaemic control and also glucose variability appears less harmful, although clinical trials in diabetic populations have not been performed yet. Diabetes is a risk factor for hypoglycaemia and evidence suggests that even near-normal glucose levels are associated with worse outcome. Taking this together, it is suggested to strive for moderate targets when treating hyperglycaemia in critically ill diabetic patients.

Oral antiplatelet therapy in diabetes mellitus and the role of prasugrel: an overview

Diabetics have a prothrombotic state that includes increased platelet reactivity. This contributes to the less favorable clinical outcomes observed in diabetics experiencing acute coronary syndromes as well as stable coronary artery disease. Many diabetics are relatively resistant to or have insufficient response to several antithrombotic agents. In the setting of percutaneous coronary intervention, hyporesponsiveness to clopidogrel is particularly common among diabetics. Several strategies have been examined to further enhance the benefits of oral antiplatelet therapy in diabetics. These include increasing the dose of clopidogrel, triple antiplatelet therapy with cilostazol, and new agents such as prasugrel. The large TRITON TIMI 38 randomized trial compared clopidogrel to prasugrel in the setting of percutaneous coronary intervention for acute coronary syndromes. The diabetic subgroup (n = 3146) experienced considerable incremental benefit with a 4.8% reduction in cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke at 15-month follow-up with prasugrel treatment. Among diabetics on insulin this combined endpoint was reduced by 7.9% at 15 months. Major bleeding was not increased in the diabetic subgroup. This confirms the general hypothesis that more potent oral antiplatelet therapy can partially overcome the prothrombotic milieu and safely improve important clinical outcomes in diabetics.

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.

Prophylactic antibiotics in aesthetic surgery

Improvements in infection prevention practices over the past several decades have enhanced outcomes following aesthetic surgery. However, surgical site infections (SSI) continue to result in increased morbidity, mortality, and cost of care. The true incidence rate of SSI in aesthetic surgery is unknown due to the lack of a national surveillance system, but studies of SSI across surgical specialties have suggested that many of these infections are preventable. Patient-related factors-including obesity, glycemic control, and tobacco use-may contribute to the development of SSI following aesthetic surgery. In terms of SSI prevention, proper handwashing and surgical skin preparation are integral. Furthermore, the administration of prophylactic antibiotics has been shown to reduce SSI following many types of surgical procedures. Unfortunately, there are few large, randomized studies examining the role of prophylactic antibiotics in aesthetic surgery. The authors review the medical literature, discuss the risks of antibiotic overutilization, and detail nonpharmacological methods for reducing the risk of SSI.

Patients with diabetes in the intensive care unit; not served by treatment, yet protected?

Diabetes is associated with severe complications and decreased life expectancy. However, in the previous issue of Critical Care, Vincent and colleagues report no difference in mortality between patients with insulin-treated diabetes and patients without diabetes in the intensive care unit (ICU), despite larger severity of illness in the diabetes group at admission. This study contributes to the growing evidence that diabetes in itself is not a risk factor for ICU mortality, although the mechanisms are not yet fully understood. On the other hand, patients with diabetes seem not to benefit from tight glycemic control during their ICU stay. Different treatment approaches may be needed for patients with diabetes and patients with stress hyperglycemia.

Insulin-treated diabetes is not associated with increased mortality in critically ill patients

Introduction

This was a planned substudy from the European observational Sepsis Occurrence in Acutely ill Patients (SOAP) study to investigate the possible impact of insulin-treated diabetes on morbidity and mortality in ICU patients.

Methods

The SOAP study was a cohort, multicenter, observational study which included data from all adult patients admitted to one of 198 participating ICUs from 24 European countries during the study period. For this substudy, patients were classified according to whether or not they had a known diagnosis of insulin-treated diabetes mellitus. Outcome measures included the degree of organ dysfunction/failure as assessed by the sequential organ failure assessment (SOFA) score, the occurrence of sepsis syndromes and organ failure in the ICU, hospital and ICU length of stay, and all cause hospital and ICU mortality.

Results

Of the 3147 patients included in the SOAP study, 226 (7.2%) had previously diagnosed insulin-treated diabetes mellitus. On admission, patients with insulin-treated diabetes were older, sicker, as reflected by higher simplified acute physiology system II (SAPS II) and SOFA scores, and more likely to be receiving hemodialysis than the other patients. During the ICU stay, more patients with insulin-treated diabetes required renal replacement therapy (hemodialysis or hemofiltration) than other patients. There were no significant differences in ICU or hospital lengths of stay or in ICU or hospital mortality between patients with or without insulin-treated diabetes. Using a Cox proportional hazards regression analysis with hospital mortality censored at 28-days as the dependent factor, insulin-treated diabetes was not an independent predictor of mortality.

Conclusions

Even though patients with a history of insulin-treated diabetes are more severely ill and more likely to have renal failure, insulin-treated diabetes is not associated with increased mortality in ICU patients.

The role of perioperative hyperglycemia in postoperative infections

In the past decade, convincing evidence has emerged that perioperative glycemic control in certain settings, especially cardiac surgery and the surgical ICU, can decrease morbidity and mortality. It remains unclear, however, if hypoglycemia is a cause of death or marker of patient acuity. It is clear, however, that the particular intensive glycemic control protocol matters because the rate of hypoglycemia varies across protocols and institutions. The best current evidence for tight control rests in the population of surgical patients needing more than 5 days of critical care. Many questions still remain, such as the optimum blood sugar or the best protocol to implement glucose control, minimizing hypoglycemia. Further information will become available from the Normogylcemia in Intensive Care Evaluation and Survival Using Glucose Algorithm Regulation trial, currently enrolling patients in a prospective randomized trial to answer some of these outstanding questions. Maintaining euglycemia postoperatively is a simple and actionable step that could decrease the risk of postoperative infections and postoperative mortality.

Inpatient insulin therapy

PURPOSE OF REVIEW

In a 2001 report from a surgical intensive care unit in Leuven, Belgium, intravenous insulin infusion targeting blood glucose 80-110 mg/dl reduced patient mortality and morbidities. Subsequent research has failed to define glycemic targets necessary or sufficient for attainment of desired health outcomes in other inpatient settings, but a large body of evidence suggests hospital outcomes are related to hyperglycemia.

RECENT FINDINGS

Recent literature describes observational evidence for hypoglycemia as an independent predictor of mortality in a general medical intensive care unit; superiority of performance of computerized intravenous insulin algorithms in comparison to earlier manual algorithms; acceptability of early transition to scheduled basal prandial correction subcutaneous insulin analog therapy for maintenance of glycemic targets after induction of euglycemia by intravenous insulin infusion, among cardiothoracic surgery patients; inferiority of sliding scale insulin compared to basal prandial correction therapy; and feasibility of diabetes patient self-management in the hospital setting.

SUMMARY

With development of improved insulin administration strategies problems of hypoglycemia and variability of glycemic control are reduced. Investigators and care providers need to achieve glycemic targets to optimize patient outcomes.