The role of hyperglycemia in burned patients: evidence-based studies

Computerized insulin infusion programs are safe and effective in the burn intensive care unit

Glucose control has repeatedly been shown to influence favorable outcomes in the surgical intensive care unit (ICU). Intensive insulin therapy has recently been associated with reduced infections complications in burn patients. However, traditional protocols are associated with rates of severe hypoglycemia as high as 19%. Two commercial computer glucose control programs have reported rates of severe hypoglycemia (glucose <50 mg/dl) of 0.6 and 0.4%. Recently, the authors' burn ICU adopted an intensive insulin computer-based protocol created at their institution and already successfully in use in their surgical ICU. The authors hypothesized that their protocol can be used effectively in the burn patient population without an increase risk of severe hypoglycemia. All patients admitted to the burn ICU have blood glucose (BG) values checked routinely. With two consecutive hyperglycemic values >200 mg/dl, patients are placed on a computer-based protocol intravenous insulin drip. Once initiated, BGs are tested hourly with adjustments made according to the computer protocol. Values recorded from January to December 2008 were abstracted from the database and analyzed. Thirty-one patients were treated using the computer glucose control protocol and 12,699 measurements were performed. There were eight measurements <50 mg/dl (0.07%). Seventy-six percent of values were within the target range of 90 to 150 mg/dl. Few patients had severe hyperglycemia with BG >300 mg/dl (0.2%). There were no adverse events associated with the hypoglycemic episode. The computer-based protocol is more effective than those previously used at the institution and provides safe, reliable results in the burn patients.

Glucose metabolism during the early "flow phase" after burn injury

BACKGROUND

Burn injury (BI) is associated with insulin resistance (IR) and hyperglycemia which complicate clinical management. We investigated the impact of BI on glucose metabolism in a rabbit model of BI using a combination of positron emission tomography (PET) and stable isotope studies under euglycemic insulin clamp (EIC) conditions.

MATERIALS AND METHODS

Twelve male rabbits were subjected to either full-thickness BI (B) or sham burn. An EIC condition was established by constant infusion of insulin, concomitantly with a variable rate of dextrose infusion 3 d after treatment. PET imaging of the hind limbs was conducted to determine the rates of peripheral O(2) and glucose utilization. Each animal also received a primed constant infusion of [6,6-(2)H(2)] glucose to determine endogenous glucose production.

RESULTS

The fasting blood glucose in the burned rabbits was higher than that in the sham group. Under EIC conditions, the sham burn group required more exogenous dextrose than the B group to maintain blood glucose at physiological levels (22.2 ± 2.6 versus 13.3 ± 2.9 mg/min, P < 0.05), indicating a state of IR. PET imaging demonstrated that the rates of O(2) consumption and (18)F 2-fluoro-2-deoxy-D-glucose utilization by skeletal muscle remained at similar levels in both groups. Hepatic gluconeogenesis determined by the stable isotope tracer study was found significantly increased in the B group.

CONCLUSIONS

These findings demonstrated that hyperglycemia and IR develop during the early "flow phase" after BI. Unsuppressed hepatic gluconeogenesis, but not peripheral skeletal muscular utilization of glucose, contributes to hyperglycemia at this stage.

Role of the PPAR-α agonist fenofibrate in severe pediatric burn

Fenofibrate is a peroxisome proliferator activated receptor alpha agonist that contains both pro and anti-inflammatory properties, and has been used in the treatment of dyslipidemia and diabetes for decades. Its receptors are expressed in the liver, skeletal muscle, cardiac, enteric, and renal cells, which allow it to provide systemic regulation of lipoprotein metabolism, fatty acid oxidation, and fatty acid transport. Hyperglycemia is a common complication found in the burn population because hepatic glucose production and catecholamine-mediated hepatic glycogenolysis are augmented. Insulin resistance occurs often in these patients and is associated with poor outcomes. In the pediatric burn population, fenofibrate has been found to ameliorate or decrease the number of hypoglycemic episodes when compared to management with insulin alone. Its mechanism of action is thought to involve an improvement in insulin signaling in skeletal muscle, as well as improvements in mitochondrial function, glucose oxidation, and insulin sensitivity. The long term use of fenofibrate in severely burned patients may improve hyperglycemia and insulin resistance, as well as improve wound healing, and reduce apoptosis, and oxidative stress.

Diabetes does not influence selected clinical outcomes in critically ill burn patients

The purpose of this study was to evaluate glucose control and clinical outcomes in diabetic burn intensive care unit (ICU) patients. The authors reviewed 462 civilian patients admitted to the burn ICU over 4 years. Exclusion criteria were age <18 years, admission because of skin infection, incomplete records, and military patients. Subjects were labeled as diabetic if they had a diagnosis of diabetes documented in their medical records. Otherwise, they were labeled as nondiabetic. Diabetic patients (n = 57) were compared with nondiabetic patients (n = 405). Admission glucose levels were obtained from chemistries. Point-of-care devices provided the remaining glucose values. While in the burn ICU, hyperglycemia for all patients was treated using intensive insulin therapy with a target blood glucose level of 80 to 110 mg/dl. Mann-Whitney U test, χ test, and multivariate regressions were used for statistical analysis (P ≤ .05). Diabetic patients were older (60 ± 15 vs 44 ± 17 years) with higher admission glucose (196 ± 81 vs 133 ± 52 mg/dl), mean glucose (147 ± 37 vs 122 ± 24 mg/dl), glucose variability (30 ± 11 vs 22 ± 11%), and fewer ICU-free days (18 ± 12 vs 20 ± 11). After multivariate regression analyses, age, injury severity score, TBSA, admission glucose, and mean glucose significantly affected the number of ventilator-free days, ICU-free days, and hospital-free days. Glucose variability was associated with hospital-free days only. Age, injury severity score, and TBSA significantly influenced mortality, whereas a preexisting diagnosis of diabetes was not associated with any clinical outcomes. Admission blood glucose is higher, and blood glucose is more difficult to control in diabetic burn ICU patients. A preexisting diagnosis of diabetes does not influence clinical outcomes in critically ill burn patients.

Glucose control in severely thermally injured pediatric patients: what glucose range should be the target?

OBJECTIVE

To determine which glucose levels are associated with improved morbidity and mortality in thermally injured patients.

SUMMARY BACKGROUND DATA

Tight euglycemic control was rapidly implemented in intensive care units around the world, but there is increasing evidence that tight euglycemic control is associated with detrimental outcomes. Currently, no study exists that indicates which glucose range should be targeted.

METHODS

Two-hundred and eight severely burned pediatric patients with burns over 30% of their total body surface area were included in this trial. Several statistical models were used to determine the daily average and 6 AM glucose target that were associated with improved morbidity and mortality. Patients were then divided into good glucose controlled and poor glucose controlled patients and demographics, clinical outcomes, infection, sepsis, inflammatory, and hypermetabolic responses were determined.

RESULTS

Statistical modeling showed that hyperglycemia is a strong predictor of adverse hospital outcome and that daily 6 am glucose level of 130 mg/dL and daily average glucose levels of 140 mg/dL are associated with improved morbidity and mortality postburn. When patients were divided into good glucose control and poor glucose control, we found that patients with glucose levels of 130 mg/dL exert attenuated hypermetabolic and inflammatory responses, as well as significantly lower incidence of infections, sepsis, and mortality compared with patients with poor glucose control, P < 0.05.

CONCLUSIONS

Given the controversy over glucose range, glucose target, and risks and detrimental outcomes associated with hypoglycemia we suggest that in severely burned patient's blood glucose of 130 mg/dL should be targeted.

The use of exenatide in severely burned pediatric patients

Introduction

Intensive insulin treatment (IIT) has been shown to improve outcomes post-burn in severely burnt patients. However, it increases the incidence of hypoglycemia and is associated with risks and complications. We hypothesized that exenatide would decrease plasma glucose levels post-burn to levels similar to those achieved with IIT, and reduce the amount of exogenous insulin administered.

Methods

This open-label study included 24 severely burned pediatric patients. Six were randomized to receive exenatide, and 18 received IIT during acute hospitalization (block randomization). Exenatide and insulin were administered to maintain glucose levels between 80 and 140 mg/dl. We determined 6 AM, daily average, maximum and minimum glucose levels. Variability was determined using mean amplitude of glucose excursions (MAGE) and percentage of coefficient of variability. The amount of administered insulin was compared in both groups.

Results

Glucose values and variability were similar in both groups: Daily average was 130 ± 28 mg/dl in the intervention group and 138 ± 25 mg/dl in the control group (P = 0.31), MAGE 41 ± 6 vs. 45 ± 12 (respectively). However, administered insulin was significantly lower in the exenatide group than in the IIT group: 22 ± 14 IU patients/day in the intervention group and 76 ± 11 IU patients/day in the control group (P = 0.01). The incidence rate of hypoglycemia was similar in both groups (0.38 events/patient-month).

Conclusions

Patients receiving exenatide received significantly lower amounts of exogenous insulin to control plasma glucose levels. Exenatide was well tolerated and potentially represents a novel agent to attenuate hyperglycemia in the critical care setting.

Trial registration

NCT00673309.