Immunologic effects of acute hyperglycemia in nondiabetic rats

Association between the stress hyperglycemia ratio and 28-day all-cause mortality in critically ill patients with sepsis: a retrospective cohort study and predictive model establishment based on machine learning

BACKGROUND

Sepsis is a severe form of systemic inflammatory response syndrome that is caused by infection. Sepsis is characterized by a marked state of stress, which manifests as nonspecific physiological and metabolic changes in response to the disease. Previous studies have indicated that the stress hyperglycemia ratio (SHR) can serve as a reliable predictor of adverse outcomes in various cardiovascular and cerebrovascular diseases. However, there is limited research on the relationship between the SHR and adverse outcomes in patients with infectious diseases, particularly in critically ill patients with sepsis. Therefore, this study aimed to explore the association between the SHR and adverse outcomes in critically ill patients with sepsis.

METHODS

Clinical data from 2312 critically ill patients with sepsis were extracted from the MIMIC-IV (2.2) database. Based on the quartiles of the SHR, the study population was divided into four groups. The primary outcome was 28-day all-cause mortality, and the secondary outcome was in-hospital mortality. The relationship between the SHR and adverse outcomes was explored using restricted cubic splines, Cox proportional hazard regression, and Kaplan‒Meier curves. The predictive ability of the SHR was assessed using the Boruta algorithm, and a prediction model was established using machine learning algorithms.

RESULTS

Data from 2312 patients who were diagnosed with sepsis were analyzed. Restricted cubic splines demonstrated a "U-shaped" association between the SHR and survival rate, indicating that an increase in the SHR is related to an increased risk of adverse events. A higher SHR was significantly associated with an increased risk of 28-day mortality and in-hospital mortality in patients with sepsis (HR > 1, P < 0.05) compared to a lower SHR. Boruta feature selection showed that SHR had a higher Z score, and the model built using the rsf algorithm showed the best performance (AUC = 0.8322).

CONCLUSION

The SHR exhibited a U-shaped relationship with 28-day all-cause mortality and in-hospital mortality in critically ill patients with sepsis. A high SHR is significantly correlated with an increased risk of adverse events, thus indicating that is a potential predictor of adverse outcomes in patients with sepsis.

Long-Term Exposure of Cultured Astrocytes to High Glucose Impact on Their LPS-Induced Activation

Diabetes mellitus is associated with various complications, mainly caused by the chronic exposure of the cells to high glucose (HG) concentrations. The effects of long-term HG exposure in vitro accompanied by lipopolysaccharide (LPS) application on astrocytes are relatively unknown. We used cell medium with normal (NG, 5.5 mM) or high glucose (HG, 25 mM) for rat astrocyte cultures and measured the release of NO, IL-6, β-hexosaminidase and cell survival in response to LPS. We first demonstrated that HG long-term incubation of astrocytes increased the release of β-hexosaminidase without decreasing MTT-detected cell survival, suggesting that there is no cell membrane damage or astrocyte death but could be lysosome exocytosis. Different from what was observed for NG, all LPS concentrations tested at HG resulted in an increase in IL-6, and this was detected for both 6 h and 48 h treatments. Interestingly, β-hexosaminidase level increased after 48 h of LPS and only at HG. The NO release from astrocytes also increased with LPS application at HG but was less significant. These data endorsed the original hypothesis that long-term hyperglycemia increases proinflammatory activation of astrocytes, and β-hexosaminidase could be a specific marker of excessive activation of astrocytes associated with exocytosis.

Positive association between stress hyperglycemia ratio and pulmonary infection in patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention

BACKGROUND

Previous studies have shown that the stress hyperglycemia ratio (SHR), a parameter of relative stress-induced hyperglycemia, is an excellent predictive factor for all-cause mortality and major adverse cardiovascular events (MACEs) among patients with ST-segment elevation myocardial infarction (STEMI). However, its association with pulmonary infection in patients with STEMI during hospitalization remains unclear.

METHODS

Patients with STEMI undergoing percutaneous coronary intervention (PCI) were consecutively enrolled from 2010 to 2020. The primary endpoint was the occurrence of pulmonary infection during hospitalization, and the secondary endpoint was in-hospital MACEs, composed of all-cause mortality, stroke, target vessel revascularization, or recurrent myocardial infarction.

RESULTS

A total of 2,841 patients were finally included, with 323 (11.4%) developing pulmonary infection and 165 (5.8%) developing in-hospital MACEs. The patients were divided into three groups according to SHR tertiles. A higher SHR was associated with a higher rate of pulmonary infection during hospitalization (8.1%, 9.9%, and 18.0%, P < 0.001) and in-hospital MACEs (3.7%, 5.1%, and 8.6%, P < 0.001). Multivariate logistic regression analysis demonstrated that SHR was significantly associated with the risk of pulmonary infection during hospitalization (odds ratio [OR] = 1.46, 95% confidence interval [CI] 1.06-2.02, P = 0.021) and in-hospital MACEs (OR = 1.67, 95% CI 1.17-2.39, P = 0.005) after adjusting for potential confounding factors. The cubic spline models demonstrated no significant non-linear relationship between SHR and pulmonary infection (P = 0.210) and MACEs (P = 0.743). In receiver operating characteristic curve, the best cutoff value of SHR for pulmonary infection was 1.073.

CONCLUSIONS

The SHR is independently associated with the risk of pulmonary infection during hospitalization and in-hospital MACEs for patients with STEMI undergoing PCI.

Immune Response to CoronaVac and Its Safety in Patients with Type 2 Diabetes Compared with Healthcare Workers

Background: Vaccines for SARS-CoV-2 have been critical for preventing disease. Previous research showed patients with diabetes have impaired immunity. This study aimed to determine the immunity to coronavirus after CoronaVac by comparing patients with type 2 diabetes (T2D) and healthcare workers (HCW). Materials and methods: A prospective cohort study evaluated immune responses and safety after two doses of CoronaVac in T2D and HCW groups at Chulabhorn Hospital. The levels of total antibodies against the receptor-binding domain (anti-RBD) of the SARS-CoV-2 spike protein at baseline and 4 weeks after vaccination were collected. The level of anti-RBD concentrations was reported as geometric mean concentration (GMC) and compared between groups using the geometric mean ratio (GMR). Results: 81 participants were included; 27 had T2D and 54 were HCW. After complete vaccination, anti-RBD concentrations were not significantly different between T2D (57.68 binding antibody units (BAU)/mL, 95% confidence interval (CI) = 29.08; 114.44) and HCW (72.49 BAU/mL, 95% CI = 55.77; 94.22) groups. Subgroup analysis showed the GMC of anti-RBD was significantly lower in T2D patients with dyslipidaemia (50.04 BAU/mL) than in T2D patients without dyslipidaemia (341.64 BAU/mL). Conclusions: The immune response at 4 weeks after two doses of CoronaVac did not significantly differ between patients with T2D and HCW.

Higher Stress Hyperglycemia Ratio Is Associated With a Higher Risk of Stroke-Associated Pneumonia

Objective

Stroke-associated pneumonia (SAP) is a frequent complication in stroke patients. This present study aimed to investigate the association between stress hyperglycemia and SAP.

Methods

Patients were screened between February 2013 and August 2020 from the First Affiliated Hospital of Wenzhou Medical University. We divided the blood glucose of the patients at admission by the glycated hemoglobin to calculate the stress hyperglycemia ratio (SHR). Binary logistic regression analysis was used to identify the association between SAP and SHR, with the confounders being controlled. Further, subgroup analyses were separately performed for stroke patients with and without diabetes.

Results

A total of 2,039 patients were finally recruited, of which 533 (26.14%) were diagnosed with SAP. SHR were divided into four quartiles in the logistic regression analysis, the highest SHR quartile (SHR ≥ 1.15) indicated a higher risk of SAP (OR = 1.57; 95% CI = 1.13–2.19, p = 0.01) in total patients. In patients without diabetes, the third quantile (SHR = 0.96–1.14) and the highest quantile (SHR ≥ 1.15) were both related to a higher risk of SAP (both p < 0.05). However, we did not find such an association in diabetic patients.

Conclusion

SHR was significantly associated with the risk of SAP in patients without diabetes. Adequate attention should be paid to the patients with high SHR levels at admission, especially those without diabetes.

Dextrose-Containing Carrier Solution for Hyperthermic Intraperitoneal Chemotherapy: Increased Intraoperative Hyperglycemia and Postoperative Complications

PURPOSE

Intraoperative hyperglycemia is associated with infectious complications in general surgery patients. This study aimed to determine if the use of lactated Ringer's (LR) carrier solution during hyperthermic intraperitoneal chemotherapy (HIPEC) would lower the incidence of intraoperative hyperglycemia and improve postoperative outcomes when compared with a standard 1.5% dextrose peritoneal dialysate carrier solution.

PATIENTS AND METHODS

This is a retrospective cohort study of 134 patients who underwent HIPEC at the University of Colorado. Perioperative glucose levels and outcomes were compared between patients who were perfused with 1.5% dextrose peritoneal dialysate carrier solution (n = 68) versus LR carrier solution (n = 66).

RESULTS

The study population consisted of patients undergoing HIPEC for appendiceal (50%), colorectal (34%), mesothelioma (8%), and ovarian cancer (5%). Intraoperative severe hyperglycemia (glucose ≥ 180 mg/dL) was significantly more common among patients perfused with a dextrose-containing carrier solution versus those perfused with LR (88% vs. 21%; p < 0.001). Patients in the dextrose cohort had significantly more severe complications (39% vs. 12%; p = 0.034), infectious complications (35% vs. 15%; p = 0.011), and organ space infections (18% vs. 5%: p = 0.026) than the LR cohort. On multivariable analysis, dextrose-containing carrier solution was significantly associated with an increased risk of postoperative infectious complications (HR 5.16; p = 0.006).

CONCLUSIONS

Intraoperative hyperglycemia is common when dextrose-containing carrier solution is used during HIPEC, and severe intraoperative hyperglycemia is strongly associated with an increased risk for infectious of complications following HIPEC. LR carrier solution should be routinely used to reduce intraoperative hyperglycemia and its associated risks.

Is intensive glucose control bad for critically ill patients? A systematic review and meta-analysis

Background: The monitoring and management of blood glucose concentration are standard practices in critical settings as hyperglycaemia has been shown close association with poorer outcomes. Several meta-analyses have revealed that intensive glucose control has no benefit in decreasing short-term mortality among critically ill patients, while the studies these meta-analyses have incorporated have been largely divergent. We aim to perform a more comprehensive meta-analysis addressing this problem to provide stronger evidence. Methods: We conducted comprehensive searches for relevant randomized controlled studies in online databases, including the Cochrane Library, EMBASE, and PubMed databases, up to September 1, 2018. The clinical data, which included all-cause mortality, severe hypoglycemia, need for RRT, infection resulting in sepsis, ICU mortality, 90-day mortality, 180-day mortality, and hospital and ICU lengths of stay, were screened and analyzed after data extraction. We applied odds ratios (ORs) to analyze dichotomous outcomes and mean differences for continuous outcomes with a random effects model. Results: A total of 57 RCTs involving a total of 21840 patients were finally included. Patients admitted to the ICU who underwent intensive glucose control showed significantly reduced all-cause mortality (OR: 0.89; 95% CI: 0.80-1.00; P=0.04; I2=32%), reduced infection rate (OR: 0.65, 95% CI: 0.51-0.82, P=0.0002; I2=47%), a lower occurrence of acquired sepsis (OR: 0.80, 95% CI: 0.65-0.99, P=0.04; I2=0%) and shortened length of ICU stay (MD: -0.70, 95% CI: -1.21--0.19, P=0.007, I2=70%) when compared to the same parameters as those treated with the usual care strategy. However, patients in the intensive glucose control group presented with a significantly higher risk of severe hypoglycemia (OR: 5.63, 95% CI: 4.02-7.87, P<0.00001; I2=67%). Conclusions: Critically ill patients undergoing intensive glucose control showed significantly reduced all-cause mortality, length of ICU stay and incidence of acquired infection and sepsis compared to the same parameters in patients treated with the usual care strategy, while the intensive glucose control strategy was associated with higher occurrence of severe hypoglycemic events.

Postoperative hyperglycemia may negatively impact cytomegalovirus infection in seropositive liver transplant recipients: a retrospective cohort study

The aim of the study was to evaluate the association between postoperative hyperglycemia and CMV infection. We analyzed 741 CMV seropositive recipients, of livers from seropositive living donors, who underwent preemptive CMV treatment without CMV prophylaxis. The primary outcome was early CMV infection within 1 month after surgery. Hyperglycemia was defined when mean postoperative blood glucose concentration was >180 mg/dl based on previous research and guidelines. Survival analysis was performed using the Fine and Gray model by accounting for the competing risk of CMV infection-unrelated death. Of the 741 recipients (hyperglycemic group, n = 287; nonhyperglycemic group, n = 454), 372 (50.2%) recipients developed cytomegalovirus (CMV) infection within 1 month after surgery. CMV infection risk was significantly higher in hyperglycemic group than in nonhyperglycemic group in univariable analysis [hazard ratio (HR) 1.34, 95% confidence interval (CI), 1.08-1.66; P = 0.007] and in multivariable analysis (HR 1.25, 95% CI 1.0-1.54; P = 0.038). CMV infection risk was also significantly associated with recipient age, graft ischemia time, model for end-stage liver disease score, and preoperative neutrophil-to-lymphocyte ratio (P < 0.05). In conclusion, preventing postoperative hyperglycemia appears to be an important factor decreasing the risk of CMV infection in seropositive liver transplant recipients undergoing preemptive CMV treatment.

A Comparison of 5% Dextrose in 0.9% Normal Saline versus Non-Dextrose-Containing Crystalloids as the Initial Intravenous Replacement Fluid in Elective Surgery

Intravenous fluid replacement in adult elective surgery is often initiated with dextrose-containing fluids. We sought to determine if this practice resulted in significant hyperglycaemia and if there was a risk of hypoglycaemia if non-dextrose-containing crystalloids were used instead.

We conducted a randomized controlled trial in 50 non-diabetic adult patients undergoing elective surgery which did not involve entry into major body cavities, large fluid shifts, or require administration of > 500 ml of intravenous fluid in the first two hours of peri-operative care. Patients received 500 ml of either 5% dextrose in 0.9% normal saline, lactated Ringer's solution, or 0.9% normal saline over 45 to 60 minutes. Plasma glucose, electrolytes and osmolality were measured prior to infusion, and at 15 minutes and one hour after completion of infusion.

None of the patients had preoperative hypoglycaemia despite average fasting times of almost 13 hours. Patients receiving lactated Ringer's and normal saline remained normoglycaemic throughout the study period. Patients receiving dextrose saline had significantly elevated plasma glucose 15 minutes after completion of infusion (11.1 (9.9–12.2, 95% CI) mmol/l). Plasma glucose exceeded 10 mmol/l in 72% of patients receiving dextrose saline. There was no significant difference in plasma glucose between the groups at one hour after infusion, but 33% of patients receiving DS had plasma glucose ≥8 mmol/l.

We conclude that initiation of intravenous fluid replacement with dextrose-containing solutions is not required to prevent hypoglycaemia in elective surgery. On the contrary, a relatively small volume of 500 ml causes significant, albeit transient, hyperglycaemia, even in non-diabetic patients.

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.

Regulation mechanism of oxidative stress induced by high glucose through PI3K/Akt/Nrf2 pathway in juvenile blunt snout bream (Megalobrama amblycephala)

This study was conducted to investigate the effects of oral administration of a high concentration of glucose on the respiratory burst, antioxidant status, and hepatic gene expression of heme oxygenase-1 (ho1) and PI3K/Akt/Nrf2-related signaling molecules in juvenile blunt snout bream (Megalobrama amblycephala). Blunt snout bream juveniles with an initial body weight of 19.94 ± 0.58 g were orally fed with a high concentration of glucose (3 g/kg body weight). The results indicated that plasma glucose exhibited a biphasic response. Acute and persistent hyperglycemia due to the oral glucose administration significantly reduced (P < 0.05) the white blood cell count, red blood cell count, and hemoglobin content and caused oxidative stress (significantly increased alanine aminotransferase, aspartate transaminase, alkaline phosphatase, and glucose levels) and early apoptosis of hepatocytes in the fish. Hepatic superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities increased rapidly (P < 0.05) as protection from oxidative stress and were downregulated (P < 0.05) because of persistent hyperglycemia. Blood respiratory burst was significantly reduced (P < 0.05) because of hyperglycemia and showed a trend that was opposite to that of plasma glucose. Slight upregulation of nrf2 mRNA and antioxidants acts as a compensative protection mechanism, and the downregulated PI3K/Akt pathway blocked this function of Nrf2. In conclusion, the PI3K/Akt pathway and Nrf2 mediated the antioxidative mechanism independently in the blunt snout bream juveniles subjected to the oral administration of a high glucose concentration.

A Case of Acute Cerebral Aspergillosis Complicating Influenza A/H1N1pdm 2009

Invasive aspergillosis is a rare complication in patients with influenza infection. Several cases of invasive pulmonary aspergillosis accompanying influenza infections were reported during the influenza A/H1N1pdm 2009. We encountered a case of acute cerebral aspergillosis in a patient with influenza A/H1N1pdm 2009 infection. A 24-year-old man with uncontrolled diabetes was diagnosed with influenza A/H1N1pdm 2009 infection. Initial evaluation indicated methicillin-sensitive Staphylococcus aureus pneumonia and diabetic ketoacidosis along with influenza. During his hospital course, multiple new rim-enhancing mass lesions not evident in the initial evaluation developed in the fronto-parietal cortical and subcortical white matter and right cerebellum. Pathology and culture results confirmed the presence of Aspergillus fumigatus. Surgical drainage combined with a total of 18 weeks of antifungal therapy resulted in complete resolution of the infection. This case demonstrates that cerebral aspergillosis can present alongside influenza in patients with diabetes or those under intensive care. Clinical suspicion of invasive aspergillosis is required for a definite diagnosis and better prognosis in such cases.

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.

The place for glycemic control in the surgical patient

BACKGROUND

Hyperglycemia is common in surgical patients and is associated with adverse outcomes. Conflicting data exist regarding the best method and the value of glycemic control in various patient populations. The contributions to hyperglycemia and the components of its control are complex and overlapping and likely contribute to the documented variation in outcomes. We provide an overview of the physiologic contributors to hyperglycemia and its control, review the differences in the major randomized trial results, and summarize the data regarding glycemic control in surgical patients.

METHODS

Major reviews of the pathophysiology of hyperglycemia in surgical patients, large randomized trials in critically ill and peri-operative populations, and meta-analyses were reviewed. Summations are provided for the critically ill population and for the peri-operative group.

RESULTS

A substantial physiologic rationale exists for the control of hyperglycemia in surgical patients during critical illness and in the peri-operative period. Randomized, controlled studies are limited predominately to critically ill populations. The data support controlling hyperglycemia to a serum glucose concentration <200 mg/dL, but the absolute target range remains controversial and studied inadequately. The data indicate the benefit of tight glycemic control using insulin to achieve a target of 80-110 mg/dL (intensive insulin therapy [IIT]) vs. a liberal target of 180-200 mg/dL in critically ill surgical patients, although hypoglycemia is more common with IIT. Inadequate studies are available in the peri-operative period to draw conclusions about non-critically ill surgical patients, but the weight of the data suggests control to < 200 mg/dL likely is beneficial.

CONCLUSIONS

Surgical patients benefit from maintaining serum glucose concentrations <200 mg/dL. Intensive insulin therapy (80-110 mg/dL), which appears beneficial in critically ill surgical patients but requires frequent measurement of glucose to avoid hypoglycemia. Further studies are needed to determine the appropriate target range and the influence of nutritional provision and other factors on outcome.

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.

Does stress-induced hyperglycemia increase the risk of perioperative infectious complications in orthopaedic trauma patients?

OBJECTIVE

To determine if hyperglycemia in postoperative orthopaedic trauma patients with no known history of diabetes mellitus is associated with an increased rate of infectious complications.

DESIGN

Retrospective review.

SETTING

University Level I trauma center.

PATIENTS

One hundred ten consecutive orthopaedic trauma patients,

MAIN OUTCOME MEASUREMENTS

Perioperative pneumonia, urinary tract infection, sepsis, or wound infection.

METHODS

Patients were divided into two subgroups based on mean serum glucose greater than 220 mg/dL (hyperglycemic index [HGI] 3.0 or greater). The incidence of infections was calculated for the following factors: age, medical comorbidities, Injury Severity Score, body mass index, HGI, sex, transfusions, tobacco use, and presence of open fracture. Means were compared using two-sample t tests (with or without adjustment for unequal variances as necessary), and percentages were compared using either chi square or Fisher exact tests. If the data were not normally distributed or measured on the ordinal scale, then the Wilcoxon rank sum test was used. A multivariate analysis using logistic regression was performed with the presence or absence of an infection as the dependent variable. A two-tailed P value < 0.05 was considered significant. SAS, Version 9.1 (SAS Institute Inc, Cary, NC), was used for all analyses.

RESULTS

Forty-six infections occurred in 28 patients, including 11 wound infections, 17 pneumonia, 11 urinary tract infections, and seven sepsis or bacteremia. The overall infection rate for the study cohort was 28 of 110 (25%). No significant associations were identified among age, comorbidities, transfusions, tobacco use, open fracture, sex, body mass index, Injury Severity Score, and the presence of any infection. Ninety nine patients had an HGI less than 3.0 and 21 (21%) of these had a perioperative infection. Eleven patients had an HGI 3.0 or greater and seven (64%) of these had a perioperative infection. This difference was significant (P = 0.0056).

CONCLUSIONS

Mean perioperative glucose levels greater than 220 mg/dL (HGI greater than 3.0) were associated with a seven times higher risk of infection in orthopaedic trauma patients with no known history of diabetes mellitus. Further prospective studies are needed to study the effects of stress-induced hyperglycemia and to determine whether this physiological response is protective or detrimental to the postoperative trauma patient.

Hyperglycemia, oxidative and nitrosative stress affect antiviral, inflammatory and apoptotic signaling of cultured thymocytes

A high prevalence of various infectious diseases is reported in diabetic patients, which may suggest impaired innate immunity against different pathogen-associated molecular patterns. This study investigated the effects of hyperglycemia, oxidative stress (H(2)O(2)), nitric oxide (NO) and peroxynitrite (ONOO(-)) on the modulation of antiviral (MDA-5, IRF-3 and phospho-IRF-3), inflammatory (NF-kappaB) and pro/anti-apoptotic molecules (Bax and Bcl-2) in BALB/c mice thymocytes. Each of the experimental conditions, except the weakest NO concentration, resulted in down-regulation of MDA-5, IRF-3 and phospho-IRF-3. In contrast, each of the experimental conditions elicited up-regulation of NF-kappaB, Bcl-2 and Bax. These results suggest that hyperglycemia, oxidative and nitrosative stress may contribute to the reduced immunity of the host by altering the MDA-5/IRF-3/phosphoIRF-3 axis, as well as contributing to the mechanisms of inflammatory reaction via increased NF-kappaB, and to augmented turnover rate of thymocyte cells via Bcl2/Bax up-regulation.

Metabolic syndrome is associated with increased risk of acute exacerbation of COPD: a preliminary study

Studies have confirmed correlation between metabolic syndrome (MetS) and chronic obstructive pulmonary disease (COPD). However, to date, no studies have analyzed correlation between exacerbations of COPD (ECOPD) and MetS. The aim of this preliminary study was to examine if presence of MetS increases the frequency and duration of ECOPD. Patients with COPD were prospectively enrolled and followed between March 2008 and September 2009. Medical records, pulmonary function tests, chest X-rays; laboratory test results were gathered to establish the presence of COPD and MetS. Patients were divided in two groups; with and without MetS. The ECOPD was defined as worsening of symptoms requiring increased use of rescue medications and/or need for either systemic steroids or antibiotics or that led to emergency room visit or hospitalizations during 12 months follow-up. A total of 106 patients were recruited, 29 with MetS and 77 without. The mean exacerbation of COPD frequency was 2.4 ± 0.8 in MetS group versus 0.68 ± 0.6 in the control group during the follow-up period (P < 0.001). Mean duration of each exacerbation was 7.5 ± 1.5 days in patients with MetS versus 5 ± 2.4 days in patients without. Serum C-reactive protein (r = 0.31, P = 0.001), fasting blood glucose (r = 0.55, P < 0.001), and triglycerides (r = 0.251, P = 0.01) were positively and significantly correlated with exacerbation frequency. This study demonstrates an association between ECOPD and its duration with the MetS. The systemic inflammation induced by common cytokines may explain the linkage between the two conditions.

Glycemic control and organ transplantation

A discussion of hyperglycemia during organ transplantation is a broad topic that includes patients with a known history of diabetes pretransplant, those at risk for post-transplant diabetes, those with stress-induced hyperglycemia, those with hyperglycemia related to immunosuppressive therapy, and hyperglycemia in the deceased organ donor. In contrast to the plethora of articles and studies describing perioperative and critical care management of hyperglycemia in cardiac, trauma, and medical/surgical intensive care unit patients, relatively few published articles in the field of organ transplantation can be found. This article consists of a review of available literature in the form of publications and abstracts, and a preliminary report of the authors' work with liver transplantation and deceased organ donors.

Glycemic control in the medical intensive care unit

Hyperglycemia in the critically ill is a well-known phenomenon, even in those without known diabetes. The stress response is due to a complex interplay between counter-regulatory hormones, cytokines, and changes in insulin sensitivity. Illness/infection, overfeeding, medications (e.g., corticosteroids), insufficient insulin, and/or volume depletion can be additional contributors. Acute hyperglycemia can adversely affect fluid balance (through glycosuria and dehydration), immune and endothelial function, inflammation, and outcome. While there are several insulin infusion protocols that are able to safely and effectively treat hyperglycemia, the bulk of accumulated evidence does not support a causal relationship between acute hyperglycemia and adverse outcomes in the medical intensive care unit. Meta-analysis of randomized controlled trials suggests there is no benefit to tightening glucose control to normal levels compared to a reasonable and achievable goal of 140 to 180 mg/dl. There is a significantly increased risk of hypoglycemia. Although there is some evidence that patients without known diabetes have worse outcomes than those with known diabetes, more recent evidence is conflicting. Glycemic control in critically ill patients should not be neglected, as studies have not tested tight versus no/poor control, but tight versus good control. A moderate approach to managing critical illness hyperglycemia seems most prudent at this juncture. Future research should ascertain whether there are certain subgroups of patients that would benefit from tighter glycemic goals. It also remains to be seen if tight glucose control is beneficial once hypoglycemia is minimized with technological advances such as continuous glucose monitoring systems.

Intraoperative glycemic control procedures and the use of an artificial pancreas

Strict intraoperative glycemic control can significantly decrease the incidence of postoperative infection; however, anesthesiologists must carefully control blood glucose levels as well as properly manage the respiratory and cardiovascular systems. However, standard blood glucose measurement systems and insulin dosing algorithms, which are necessary for achieving strict glycemic control, have not yet been developed. An artificial pancreas (STG-22^TM; Nikkiso Co., Tokyo, Japan) is considered a highly accurate blood glucose monitoring system capable of closed-loop control of blood glucose. The device has, however, many problems to be addressed since it is a large and expensive system with little versatility, and it requires a large amount of blood to be collected. Therefore, the development of less invasive and inexpensive systems with future technological progress is greatly anticipated.

Insulin resistance despite tight glucose control is associated with mortality in critically ill surgical patients

BACKGROUND

The hyperglycemic state following trauma and surgery is related partially to insulin resistance (IR). The objective is to determine if critically ill surgical patients vary in their extent of IR and is IR associated with mortality.

METHODS

Prospective observational study in trauma and surgical intensive care units. There were 925 ventilated, critically ill surgical patients who were placed on an automated euglycemia protocol. A mathematic multiplier (M) employed by the protocol was used as a measure of IR. Outcome, phenotypic, laboratory, and treatment variables were analyzed.

RESULTS

54,141 entries for glucose (mg/dl) and M were analyzed. Median glucose was 118mg/dL, with 45% of values between 80-110mg/dL, 81% between 80-150 mg/dL, and 0.2% less than 40 mg/ dL. M varied by 42 fold over the entire population, and by an average of 11-fold among individual patients. The median blood glucose was not different between groups (118 mg/dl for survivors and 118 mg/dl for non-survivors, P = 0.36). The median insulin dose and M were significantly higher in non-survivors (4.1 U/hr versus 3.4 U/hr, P = 0.005; 0.061 versus 0.058, P = 0.02).

CONCLUSIONS

There was a large amount of variation in insulin resistance, as measured by an adapting multiplier, both across the population and within patients. In the setting of tight glucose control measures of glucose control (median blood glucose and percent in range) do not differentiate between patients who lived and died while measures of insulin resistance (median insulin dose and multiplier) do, suggesting that the insulin resistance is a better predictor of outcome.

Tumor necrosis factor-alpha mediates hyperglycemia-augmented gut barrier dysfunction in endotoxemia

OBJECTIVE

To examine whether hyperglycemia would augment gut barrier dysfunction and inflammatory responses in endotoxemic rats, and simultaneously to clarify the roles of tumor necrosis factor (TNF)-alpha in alterations of gut mucosal permeability associated with hyperglycemia.

DESIGN

Prospective randomized animal study.

SETTING

University research laboratory.

SUBJECTS

: Male Wistar rats treated with lipopolysaccharide (LPS) injection.

INTERVENTIONS

After LPS injection (4 mg/kg), rats were randomly allocated into group S (n = 6), group G (n = 7), or group GI (n = 8) with continuous infusion of different fluid solutions: normal saline, 40% glucose or 10% glucose mixed with insulin, respectively. Blood glucose, insulin, and proinflammatory cytokines, accompanied by gut mucosal permeability using an in situ loop preparation of gut with fluorescence isothiocyanate-conjugated dextran, were measured. Bacterial growth or alterations in mesenteric lymph nodes and cecal contents were also assessed. We further determined the roles of TNF-alpha using an inhibitor of TNF-alpha converting enzyme in gut barrier dysfunction under the same experimental settings.

MEASUREMENTS AND MAIN RESULTS

Hyperglycemia over 400 mg/dL was achieved and kept in group G during the study period whereas normoglycemia was preserved in group S and GI, the latter of which showed the similar extent of hyperinsulinemia to group G. Plasma concentrations of fluorescence-labeled dextran and TNF-alpha in group G were significantly higher vs. group S and GI, and the number of bacteria found in mesenteric lymph nodes in group G was greater compared with group S. Intestinal environments including microflora and organic acids were not altered by blood glucose or insulin level. Inhibiting conversion of membrane-bound to soluble type of TNF-alpha restored gut mucosal permeability augmented by hyperglycemia.

CONCLUSIONS

These findings indicate that hyperglycemia deteriorates LPS-elicited gut barrier dysfunction and bacterial translocation independently of plasma insulin level, and that TNF-alpha mediates such mucosal dysfunction of gut in endotoxemia.

Stress insulin resistance is a marker for mortality in traumatic brain injury

BACKGROUND

Both hyper- and hypoglycemia have been associated with poor outcome in traumatic brain injury (TBI). Neither the risks nor benefit of tight glucose control (goal range, 80-110 mg/dL) have been documented in the TBI population.

OBJECTIVE

To analyze whether densely collected blood glucose data, using a computerized algorithm, to maintain tight glycemic control will reveal significant differences in blood glucose control between survivors and nonsurvivors in patients with TBI.

METHODS

From October 2005 to April 2006, all ventilated, critically ill surgical patients with TBI Abbreviated Injury Scale score of >or=3 were placed on an automated, euglycemia protocol with every 2-hour blood glucose sampling. Mortalities within 24 hours were excluded. The protocol calculates the insulin rate using a linear equation (rate = blood glucose - 60[M]). M is an adapting multiplier and used here as a marker for insulin resistance (IR).

RESULTS

Of 1,636 trauma intensive care unit admissions 160 patients, (median Injury Severity Score 34, mortality 13.1%) had 10,071 samples collected. Median glucose 115.6 mg/dL, with 41% of values between 80 and 110 mg/dL, 81% between 80 and 150 mg/dL, and 0.3% <40 mg/dL. The median blood glucose was statistically different but not clinically different among the patients who lived and died (114; interquartile range, 109-132 vs. 118; 111-136, p = 0.01). The median insulin dose was a unit per hour higher among the patient who died (4.2; 2.7-5.9 vs. 3.2; 2.4-5.0, p = 0.006). A logistic regression model demonstrated insulin rate (odds ratio 0.736, 95% confidence interval, 0.549-0.985, p = 0.039) to be the only independent predictor of mortality among the measures of blood glucose control.

CONCLUSION

Nonsurvivors with TBI have significantly higher markers of IR (insulin rate and multiplier). Markers of glucose control (median glucose, hypoglycemic episodes, and the percentage of values in range) did not differ clinically among groups. Despite this stress IR, tight glycemic control appears possible and safe with low levels of hypoglycemic episodes in the TBI population.

Intensive insulin therapy and mortality in critically ill patients

INTRODUCTION

Intensive insulin therapy (IIT) with tight glycemic control may reduce mortality and morbidity in critically ill patients and has been widely adopted in practice throughout the world. However, there is only one randomized controlled trial showing unequivocal benefit to this approach and that study population was dominated by post-cardiac surgery patients. We aimed to determine the association between IIT and mortality in a mixed population of critically ill patients.

METHODS

We conducted a cohort study comparing three consecutive time periods before and after IIT protocol implementation in a Level 1 trauma center: period I (no protocol); period II, target glucose 80 to 130 mg/dL; and period III, target glucose 80 to 110 mg/dL. Subjects were 10,456 patients admitted to intensive care units (ICUs) between 1 March 2001 and 28 February 2005. The main study endpoints were ICU and hospital mortality, Sequential Organ Failure Assessment score, and occurrence of hypoglycemia. Multivariable regression analysis was used to evaluate mortality and organ dysfunction during periods II and III relative to period I.

RESULTS

Insulin administration increased over time (9% period I, 25% period II, and 42% period III). Nonetheless, patients in period III had a tendency toward higher adjusted hospital mortality (odds ratio [OR] 1.15, 95% confidence interval [CI] 0.98, 1.35) than patients in period I. Excess hospital mortality in period III was present primarily in patients with an ICU length of stay of 3 days or less (OR 1.47, 95% CI 1.11, 1.93 There was an approximately fourfold increase in the incidence of hypoglycemia from periods I to III.

CONCLUSION

A policy of IIT in a group of ICUs from a single institution was not associated with a decrease in hospital mortality. These results, combined with the findings from several recent randomized trials, suggest that further study is needed prior to widespread implementation of IIT in critically ill patients.

Management of invasive pulmonary aspergillosis in non-neutropenic critically ill patients

During recent years, a rising incidence of invasive pulmonary aspergillosis (IPA) in non-neutropenic critically ill patients has been reported. Critically ill patients are prone to develop disturbances in immunoregulation during their stay in the ICU, which render them more vulnerable for fungal infections. Risk factors such as chronic obstructive pulmonary disease (COPD), prolonged use of steroids, advanced liver disease, chronic renal replacement therapy, near-drowning and diabetes mellitus have been described. Diagnosis of IPA may be difficult and obtaining histo- or cytopathological demonstration of the fungus in order to meet the gold standard for IPA is not always feasible in these patients. Laboratory markers used as a non-invasive diagnostic tool, such as the galactomannan antigen test (GM), 1,3-beta-glucan, and Aspergillus PCR, show varying results. Antifungal therapy might be considered in patients with persistent pulmonary infection who exhibit risk factors together with positive cultures or sequentially positive GM and Aspergillus PCR in serum, in whom voriconazole is the drug of choice. The benefit of combination antifungal therapy lacks sufficient evidence so far, but this treatment might be considered in patients with breakthrough infections or refractory disease.

Glycemic control and prevention of perioperative infection

PURPOSE OF REVIEW

Hyperglycemia is common during perioperative management of surgical and critically ill patients. There is extensive ongoing study of detrimental effects associated with hyperglycemia, with several remaining unanswered questions. This review discusses recent literature on tight glucose control with insulin therapy and its effects in prevention and management of infection.

RECENT FINDINGS

Hyperglycemia affects multiple pathways of the immune system, resulting in decreased phagocytic and chemotactic functions in neutrophils and monocytes, as well as increased rates of apoptosis of the former and decreased ability of the latter to present antigen. Intensive insulin therapy has been shown to counteract many of these deleterious effects. Clinically, the benefits of tight glucose control have been evaluated in different patient populations with conclusions that remain varied. Hypoglycemia as a complication of tight glucose control continues to be an issue and has led to discontinuation of two large-scale studies. The clinical relevance of hypoglycemic events remains unclear.

SUMMARY

Hyperglycemia impairs the cellular immune system, stimulates inflammatory cytokines, and affects the microcirculation, thus increasing risk for infection and preventing normal wound healing. Additional investigation is needed to define appropriate patient populations and to develop effective treatment strategies for preventing perioperative morbidity.

Cytokine production and hospital mortality in patients with sepsis-induced stress hyperglycemia

OBJECTIVES

To investigate whether stress hyperglycemia affects the production of the main pro- and anti-inflammatory cytokines and the 28-day hospital mortality in patients with severe sepsis.

METHODS

The study included 62 patients with severe sepsis, divided in three groups according to their glycemic profile within 24h after admission: patients with stress hyperglycemia (group SH, n=16), diabetes mellitus type II (group DM, n=27), and normal glucose levels (group NG, n=19). The serum levels of the cytokines TNF-alpha, IL-6, IL-10 and TGFbeta-1 were measured within 24h after admission.

RESULTS

A higher percentage of septic patients with stress hyperglycemia died compared to diabetic patients (43.7 vs. 14.8%) and group NG (43.7 vs. 5.2%). Group SH had higher SOFA score and levels of IL-6 and IL-10 than group DM and group NG. It also had higher levels of TNF-alpha than group DM but not group NG. There was no difference in the levels of TGFbeta-1 among the three groups. Non-survivors had higher levels of IL-10, no difference was detected for IL-6, TNF-alpha, IL-10/TNF-alpha ratio and TGFbeta-1. Interleukin-10 values, mean fasting glucose values and age were found as prognostic factors associated with outcome.

CONCLUSIONS

Stress hyperglycemia is associated with increased cytokine production and an adverse clinical outcome in patients with severe sepsis.

Effect of intraoperative hyperglycemia during liver transplantation

BACKGROUND

Intensive blood glucose management has been shown to decrease mortality and infections for intensive care patients. The effect of intraoperative strict glucose control on surgical outcomes, including liver transplantation, has not been well evaluated.

MATERIALS AND METHODS

A retrospective review of all adult liver recipients transplanted between January 1, 2004 and July 6, 2006 was performed. Donor and recipient demographics, intraoperative variables, and outcomes were collected. Intraoperative glucose measurements were performed by the anesthesiology team and treated with intravenous insulin bolus or continuous infusion. Patients with strict glycemic control (mean blood glucose <150 mg/dL) were compared with those with poor control (mean blood glucose >or=150 mg/dL).

RESULTS

During the study period, a total of 184 patients met criteria for analysis. Recipients with strict glycemic control (n=60) had a mean glucose of 135 mg/dL compared with 184 mg/dL in the poorly controlled group (n=124). Other than recipient age (strict versus poor control, 47 +/- 2 y versus 53 +/- 1 y; P<0.01), both groups had similar donor and recipient characteristics. Although the incidence of most postoperative complications were similar, poor glycemic control was associated with a significantly increased infection rate at 30 d posttransplant (48% versus 30%; P=0.02), and also an increased 1 y mortality (21.9% versus 8.8%; P=0.05).

CONCLUSIONS

Intraoperative hyperglycemia during liver transplantation was associated with an increased risk of postoperative infection and mortality. Strict intraoperative glycemic control, possibly using insulin infusions, may improve outcomes following liver transplantation.

Acute effects of hyperglycemia and hyperinsulinemia on hepatic oxidative stress and the systemic inflammatory response in rats

OBJECTIVES

Intensive blood glucose control to a target value of 80-110 mg/dL has been shown to reduce morbidity and mortality in surgical intensive care unit patients. This was attributed predominantly to correction of hyperglycemia, based on multivariate regression analysis. However, the effects of glucose and insulin have not been independently evaluated. This study investigated the development of hepatic oxidative processes and systemic inflammatory response in rats with different levels of induced hyperglycemia and hyperinsulinemia. The effects of a modest increase in blood glucose following glucose infusion at a level adequate to meet energy requirements, hyperinsulinemia induced by a hyperinsulinemic euglycemic clamp with administered glucose in similar amounts, and marked hyperglycemia and hyperinsulinemia secondary to glucose infusion on hepatic oxidative stress and systemic inflammatory response in vivo were examined.

DESIGN

Controlled laboratory study.

SETTING

Medical school laboratory.

SUBJECTS

Specific pathogen-free male Sprague-Dawley rats.

INTERVENTIONS

Blood glucose was monitored over 3 hrs. At the end of study, the serum concentrations of insulin, tumor necrosis factor-alpha, interleukin-1, and alpha1 acid glycoprotein were determined. Malondialdehyde and total glutathione content were measured in the liver.

MEASUREMENTS AND MAIN RESULTS

Glucose infusion adequate to provide energy requirements resulted in a modest increase in blood glucose (143+/-8 mg/dL) and hyperinsulinemia (45 microU/mL) and did not induce measurable hepatic oxidative stress or systemic inflammation. A hyperinsulinemic euglycemic clamp (insulin 112+/-9 microU/mL) resulted in evidence of increased oxidative processes in the liver but no change in hepatic antioxidant capacity or evidence of systemic inflammation. When hyperglycemia (approximately 350 mg/dL) and hyperinsulinemia (167+/-9 microU/mL) were induced by excess glucose infusion, rats manifested hepatic oxidative stress, antioxidant depletion, and a mild systemic inflammatory response.

CONCLUSIONS

Hyperglycemia is a major cause of the systemic inflammatory response. Maintaining normal blood glucose, by avoiding overfeeding and providing insulin therapy when necessary, appears key to minimizing oxidative stress and systemic inflammation when intravenous nutrition is provided.

Intraoperative Infusion of Amino Acids Induces Anabolism Independent of the Type of Anesthesia

BACKGROUND

The infusion of dextrose in patients receiving epidural and light general anesthesia or general anesthesia alone failed to achieve a positive protein balance. We sought to verify the hypothesis that nutritional supplementation with i.v. amino acids induced a greater protein balance in patients receiving epidural blockade compared with those receiving general anesthesia.

METHODS

Sixteen patients were randomly assigned to receive either general anesthesia with desflurane (control group) or general anesthesia combined with epidural analgesia (EDA group). A primed constant infusion of stable isotope tracers L-[1-(13)C]leucine and [6,6-(2)H2]glucose was started after a 32-h fast before surgery, (3 h of fasted state), and continued for 3 h during surgery during which amino acids were infused i.v. (fed state).

RESULTS

Compared with the fasted state, the endogenous rate of appearance of leucine decreased to a similar extent in both groups, and protein synthesis increased, with no difference between the two groups. Leucine oxidation did not change in either group. After amino acids infusion, endogenous glucose production remained unchanged and glucose clearance decreased in both groups. Blood glucose, plasma cortisol, serum insulin, and glucagon concentrations increased to the same extent in both groups.

CONCLUSIONS

Epidural anesthesia provided no additional benefit beyond the anabolism obtained with amino acids.

A concomitant review of the effects of diabetes mellitus and hypothyroidism in wound healing

This paper reviews the negative impact of diabetes mellitus or hypothyroidism on wound healing, both in experimental and clinical settings. Since both are metabolic disorders of great clinical importance, special attention is given, not only to their pathophysiology, but also to their biochemical and histological effects on tissue integrity and regeneration. Also, special focus is awarded on wound healing of the gastrointestinal tract, i.e. in intestinal anastomosis, and how these disorders can lead to wound dehiscence. Since diabetes mellitus and hypothyroidism can coexist in clinical settings, more research must be directed on their influence on wound healing, considering them as one clinical entity.

Survival benefits of intensive insulin therapy in critical illness: impact of maintaining normoglycemia versus glycemia-independent actions of insulin

Tight blood glucose control with insulin reduces morbidity and mortality of critically ill patients. However, the relative impact of maintaining normoglycemia and of glycemia-independent actions of insulin remains unknown. We therefore independently manipulated blood glucose and plasma insulin levels in burn-injured, parentally fed rabbits over 7 days to obtain four study groups: two normoglycemic groups with either normal or elevated insulin levels and two hyperglycemic groups with either normal or elevated insulin levels. We studied the relative impact of glycemia and glycemia-independent effects of insulin on survival; myocardial contractility in an open chest preparation; endothelial function in isolated aortic rings; and liver, kidney, and leukocyte function in a rabbit model of critical illness. Mortality was significantly lower in the two normoglycemic groups independent of insulin levels. Maintaining normoglycemia, independent of insulin levels, prevented endothelial dysfunction as well as liver and kidney injury. To increase myocardial systolic function, elevated insulin levels and prevention of hyperglycemia were required concomitantly. Leukocyte dysfunction was present in the two hyperglycemic groups, which could in part be rescued by insulin. The results suggest that the observed benefits of intensive insulin therapy required mainly maintenance of normoglycemia; whereas glycemia-independent actions of insulin exerted only minor, organ-specific impact.

Hyperglycemia in the intensive care unit: no longer just a marker of illness severity

BACKGROUND

Hyperglycemia is a common occurrence in critically ill patients. Recent evidence has demonstrated improved survival in patients in surgical intensive care units (SICUs) receiving "tight glycemic control." The mechanisms of this survival advantage are not well understood.

METHODS

A review of the English language literature pertaining to potential mechanisms affecting outcome in critically ill patients receiving insulin therapy, including recently published human trials evaluating mortality outcomes.

RESULTS

This review discusses the results of clinical trials of "tight glycemic control," considers mechanisms of hyperglycemia in critical illness, and reviews potential mechanisms of improved outcome related in the critically ill patient.

CONCLUSIONS

A number of human studies have demonstrated improved outcomes in critically ill patient populations receiving insulin therapy with a target of euglycemia, suggesting at least part of the benefit of this therapy is normal blood sugar and not the effects of insulin. An important population not studied to date is patients in the medical ICU. However, aggressive control of hyperglycemia now remains an important component of care for all surgical patients in the ICU.

Glucose in bronchial aspirates increases the risk of respiratory MRSA in intubated patients

BACKGROUND

The risk of nosocomial infection is increased in critically ill patients by stress hyperglycaemia. Glucose is not normally detectable in airway secretions but appears as blood glucose levels exceed 6.7-9.7 mmol/l. We hypothesise that the presence of glucose in airway secretions in these patients predisposes to respiratory infection.

METHODS

An association between glucose in bronchial aspirates and nosocomial respiratory infection was examined in 98 critically ill patients. Patients were included if they were expected to require ventilation for more than 48 hours. Bronchial aspirates were analysed for glucose and sent twice weekly for microbiological analysis and whenever an infection was suspected.

RESULTS

Glucose was detected in bronchial aspirates of 58 of the 98 patients. These patients were more likely to have pathogenic bacteria than patients without glucose detected in bronchial aspirates (relative risk 2.4 (95% CI 1.5 to 3.8)). Patients with glucose were much more likely to have methicillin resistant Staphylococcus aureus (MRSA) than those without glucose in bronchial aspirates (relative risk 2.1 (95% CI 1.2 to 3.8)). Patients who became colonised or infected with MRSA had more infiltrates on their chest radiograph (p<0.001), an increased C reactive protein level (p<0.05), and a longer stay in the intensive care unit (p<0.01). Length of stay did not determine which patients acquired MRSA.

CONCLUSION

The results imply a relationship between the presence of glucose in the airway and a risk of colonisation or infection with pathogenic bacteria including MRSA.

Intraoperative protein sparing with glucose

We examined the hypothesis that glucose infusion inhibits amino acid oxidation during colorectal surgery. We randomly allocated 14 patients to receive intravenous glucose at 2 mg·kg−1·min−1 (glucose group) starting with the surgical incision or an equivalent amount of normal saline 0.9% (control group). The primary endpoint was whole body leucine oxidation; secondary endpoints were leucine rate of appearance and nonoxidative leucine disposal as determined by a stable isotope tracer technique (l-[1-13C]leucine). Circulating concentrations of glucose, lactate, insulin, glucagon, and cortisol were measured before and after 2 h of surgery. Leucine rate of appearance, an estimate of protein breakdown, and nonoxidative leucine disposal, an estimate of protein synthesis, decreased in both groups during surgery ( P < 0.05). Leucine oxidation intraoperatively decreased from 13 ± 3 to 4 ± 3 μmol·kg−1·h−1 in the glucose group ( P < 0.05 vs. control group) whereas it remained unchanged in the control group. Hyperglycemia during surgery was more pronounced in patients receiving glucose (9.7 ± 0.5 mmol/l, P < 0.05 vs. control group) than in patients receiving normal saline (7.1 ± 1.0 mmol/l). The administration of glucose caused an increase in the circulating concentration of insulin ( P < 0.05) resulting in a lower glucagon/insulin quotient than in the control group ( P < 0.05). Intraoperative plasma cortisol concentrations increased in both groups ( P < 0.05), whereas plasma concentrations of lactate and glucagon did not change. The provision of small amounts of glucose was associated with a decrease in amino acid oxidation during colorectal surgery.

Acute hyperglycemia and the innate immune system: clinical, cellular, and molecular aspects

OBJECTIVE

To extract from the biomedical literature the reported effects of acute hyperglycemia on the major components of the innate immune system and to describe the clinical benefits of strict blood glucose control in certain patients.

DATA SOURCE AND SELECTION

A Medline/PubMed search (1966 to July 2004) with manual cross-referencing was conducted, including all relevant articles investigating the effects of acutely elevated glucose levels on innate immunity. All publication types, languages, or subsets were searched.

DATA EXTRACTION AND SYNTHESIS

Original and selected review articles, short communications, letters to the editor, and chapters of selected textbooks were extracted. Most recent and relevant clinical trials were reviewed for the introductory section to provide the clinical background to this topic. The selected bench laboratory articles were then divided into three main categories based on the timing of events: a) the early phase of the innate immune reaction; b) the cytokine network; and c) the phagocytic phase. The most obvious findings related to hyperglycemia included reduced neutrophil activity (e.g., chemotaxis, formation of reactive oxygen species, phagocytosis of bacteria), despite accelerated diapedesis of leukocytes into peripheral tissue, as well as specific alterations of cytokine patterns with increased concentrations of the early proinflammatory cytokines tumor necrosis factor-alpha and interleukin-6. Furthermore, a reduction of endothelial nitric oxide formation takes place, thus decreasing microvascular reactivity to dilating agents such as bradykinin, and complement function (e.g., opsonization, chemotaxis) is impaired, despite elevations of certain complement factors.

CONCLUSIONS

Acute, short-term hyperglycemia affects all major components of innate immunity and impairs the ability of the host to combat infection, even though certain distinctive proinflammatory alterations of the immune response can be observed under these conditions.