Elizabeth A. Mann

Comparison of Mortality Associated with Sepsis in the Burn, Trauma, and General Intensive Care Unit Patient: A Systematic Review of the Literature

ABSTRACT The purpose of this systematic review of the literature was to determine the association of sepsis with mortality in the severely injured adult patient by means of a comparative analysis of sepsis in burn and trauma injury with other critically ill populations. The MEDLINE (PubMed), Cochrane Library, and ProQuest databases were searched. The following keywords and MeSH headings were used: “sepsis,” septicemia,” “septic shock,” “epidemiology,” “burns,” “thermal injury,” “trauma,” “wounds and injuries,” “critical care,” “intensive care,” “outcomes,” and “mortality.” Included studies were clinical studies of adult burn, trauma, and critically ill patients that reported survival data for sepsis. Thirty-eight articles were reviewed (9 burn, 11 trauma, 18 general critical care). The age of burn (<45 years) and trauma (34–49 years) groups was lower than the general critical care (57–64 years) population. Sepsis prevalence varied with trauma-injured patients experiencing fewer episodes (2.4%–16.9%) contrasted with burn patients (8%–42.5%) and critical care patients (19%–38%). Survival differed with trauma patients experiencing a lower rate of mortality associated with sepsis (7%–36.9%) compared with the burn (28%–65%) and critical care (21%–53%) groups. This study is the first to compare sepsis outcomes in three distinct patient populations: burn, trauma, and general critical care. Trauma patients tend to have relatively low sepsis-associated mortality; burn patients and the older critical care population have higher prevalence of sepsis with worse outcomes. Great variability of criteria to identify septic patients among studies compromises population comparisons.

Computerized decision support system improves fluid resuscitation following severe burns: An original study

Objective:Several formulas have been developed to guide resuscitation in severely burned patients during the initial 48 hrs after injury. These approaches require manual titration of fluid that may result in human error during this process and lead to suboptimal outcomes. The goal of this study was to analyze the efficacy of a computerized open-loop decision support system for burn resuscitation compared to historical controls. Design:Fluid infusion rates and urinary output from 39 severely burned patients with >20% total body surface area burns were recorded upon admission (Model group). A fluid-response model based on these data was developed and incorporated into a computerized open-loop algorithm and computer decision support system. The computer decision support system was used to resuscitate 32 subsequent patients with severe burns (computer decision support system group) and compared with the Model group. Setting:Burn intensive care unit of a metropolitan Level 1 Trauma center. Patients:Acute burn patients with >20% total body surface area requiring active fluid resuscitation during the initial 24 to 48 hours after burn. Measurements and Main Results:We found no significant difference between the Model and computer decision support system groups in age, total body surface area, or injury mechanism. Total crystalloid volume during the first 48 hrs post burn, total crystalloid intensive care unit volume, and initial 24-hr crystalloid intensive care unit volume were all lower in the computer decision support system group. Infused volume per kilogram body weight (mL/kg) and per percentage burn (mL/kg/total body surface area) were also lower for the computer decision support system group. The number of patients who met hourly urinary output goals was higher in the computer decision support system group. Conclusions:Implementation of a computer decision support system for burn resuscitation in the intensive care unit resulted in improved fluid management of severely burned patients. All measures of crystalloid fluid volume were reduced while patients were maintained within urinary output targets a higher percentage of the time. The addition of computer decision support system technology improved patient care.

Use of procalcitonin for the detection of sepsis in the critically ill burn patient: A systematic review of the literature

The purpose of this systematic review was to assess the evidence for use of routine procalcitonin testing to diagnose the presence of sepsis in the burn patient. The electronic databases MEDLINE, Cochrane, CINAHL, ProQuest, and SCOPUS were searched for relevant studies using the MeSH terms burn, infection, procalcitonin, and meta-analysis. The focus of the review was the adult burn population, but other relevant studies of critically ill patients were included as data specific to the patient with burns are limited. Studies were compiled in tabular form and critically appraised for quality and level of evidence. Four meta-analyses, one review of the literature, one randomized controlled trial, nine prospective observational, and three retrospective studies were retrieved. Six of these studies were specific to the burn population, with one specific to burned children. Only one meta-analysis, one adult burn and one pediatric burn study reported no benefit of procalcitonin testing to improve diagnosis of sepsis or differentiate sepsis from non-infectious systemic inflammatory response. The collective findings of the included studies demonstrated benefit of incorporating procalcitonin assay into clinical sepsis determination. Evaluation of the burn specific studies is limited by the use of guidelines to define sepsis and inconsistent results from the burn studies. Utility of the procalcitonin assay is limited due to the lack of availability of rapid, inexpensive tests. However, it appears procalcitonin assay is a safe and beneficial addition to the clinical diagnosis of sepsis in the burn intensive care unit.

Anemia causes hypoglycemia in intensive care unit patients due to error in single-channel glucometers: Methods of reducing patient risk

Objective: Intensive insulin therapy in the critically ill reduces mortality but carries the risk of increased hypoglycemia. Point-of-care blood glucose analysis is standard; however, anemia causes falsely high values and potentially masks hypoglycemia. Permissive anemia is practiced routinely in most intensive care units. We hypothesized that point-of-care glucometer error due to anemia is prevalent, can be corrected mathematically, and correction uncovers occult hypoglycemia during intensive insulin therapy. Design: The study has both retrospective and prospective phases. We reviewed data to verify the presence of systematic error, determine the source of error, and establish the prevalence of anemia. We confirmed our findings by reproducing the error in an in vitro model. Prospective data were used to develop a correction formula validated by the Monte Carlo method. Correction was implemented in a burn intensive care unit and results were evaluated after 9 mos. Setting: Burn and trauma intensive care units at a single research institution. Patients/Subjects: Samples for in vitro studies were taken from healthy volunteers. Samples for formula development were from critically ill patients who received intensive insulin therapy. Interventions: Insulin doses were calculated based on predicted serum glucose values from corrected point-of-care glucometer measurements. Measurements and Main Results: Time-matched point-of-care glucose, laboratory glucose, and hematocrit values. We previously found that anemia (hematocrit <34%) produces systematic error in glucometer measurements. The error was correctible with a mathematical formula developed and validated, using prospectively collected data. Error of uncorrected point-of-care glucose ranged from 19% to 29% (p < .001), improving to ≤5% after mathematical correction of prospective data. Comparison of data pairs before and after correction formula implementation demonstrated a 78% decrease in the prevalence of hypoglycemia in critically ill and anemic patients treated with insulin and tight glucose control (p < .001). Conclusions: A mathematical formula that corrects erroneous point-of-care glucose values due to anemia in intensive care unit patients reduces the prevalence of hypoglycemia during intensive insulin therapy.

Error rates resulting from anemia can be corrected in multiple commonly used point-of-care glucometers

BACKGROUND A point-of-care (POC) glucometer (G1) used for critical care at our institution is inaccurate in the presence of low hematocrit (HCT) values. The purpose of this study was to analyze error rates of three additional POC glucometer brands and determine mathematical correction formulas for each. METHODS Blood samples (n = 196) from a cohort of surgical, trauma, medical, cardiothoracic, and burn intensive care unit patients were tested on three commonly used POC glucometer brands (G2-G4). Results were compared with reference laboratory values, and correction compared with the validated formula for G1. A mathematical formula specific to each glucometer type was derived from glucose measurements, associated HCT values, and the degree of difference relative to laboratory results. RESULTS POC glucometer results were consistently elevated compared with reference laboratory values. Glucometer error rates for HCT </= 25% ranged from 15.4% to 22.3% for the three types. Error rates for 25% < HCT < 34% ranged from 16.4% to 18.4%. A correction formula for each glucometer based on the natural log transformation of the HCT predicted reference values with a mean error rate of -0.54% +/- 5.6% for G2, -0.6% +/- 5.5% for G3, and 0.2% +/- 8.0% for G4. Correction was similar to that previously established for G1 (-0.01% +/- 4.8). CONCLUSIONS Significant error rates because of HCT effect were found in all glucometer models tested with accurate prediction of reference values with a simple mathematical formula.

Loss of protein, immunoglobulins, and electrolytes in exudates from negative pressure wound therapy

BACKGROUND A relatively new technology in wound care, negative pressure wound therapy (NPWT), has become widely used for the management of open abdomens and soft tissue wounds and provides a means to collect wound exudate to quantify protein loss. METHODS A prospective observational study was conducted in surgical, trauma, or burn patients (8 patients with open abdomens and 9 patients with acute soft tissue wounds on NPWT). NPWT exudate was collected and assayed to characterize loss of protein, electrolyte, and immunoglobulins over multiple days of NPWT. RESULTS Total protein was present in open abdomen NPWT exudate, 2.9 ± 0.9 g/dL. In the soft tissue wound exudate, a similar mean concentration was found, 2.59 ± 0.6 g/dL (P = .34). Exudate concentrations of albumin, urea nitrogen, immunoglobulins, and electrolytes between wound types were also not significantly different. There were significant (P = .03) differences in the median volume of exudate, 1031 mL/d for open abdomens in contrast to 245 mL/d soft tissue wounds. Therefore, 24-hour losses of proteins and electrolytes were greater in patients with open abdomens than soft tissue wounds. Mean total protein loss was 25 ± 17 g/d for open abdomens and 8 ± 5 g/d for soft tissue wounds. CONCLUSION There are significant losses of proteins in wound exudate. As there is no significant difference in the concentration of total protein between wound type, the rate of loss may be calculated as 2.9 g/dL times the volume of wound exudate. The rate of protein loss from wounds is similar to the presently assumed insensible loss rate of 12-25 g/d.

Correlation of American Burn Association sepsis criteria with the presence of bacteremia in burned patients admitted to the intensive care unit.

Severe burn injury is accompanied by a systemic inflammatory response, making traditional indicators of sepsis both insensitive and nonspecific. To address this, the American Burn Association (ABA) published diagnostic criteria in 2007 to standardize the definition of sepsis in these patients. These criteria include temperature (>39°C or <36°C), progressive tachycardia (>110 beats per minute), progressive tachypnea (>25 breaths per minute not ventilated or minute ventilation >12 L/minute ventilated), thrombocytopenia (<100,000/&mgr;l; not applied until 3 days after initial resuscitation), hyperglycemia (untreated plasma glucose >200 mg/dl, >7 units of insulin/hr intravenous drip, or >25% increase in insulin requirements over 24 hours), and feed intolerance >24 hours (abdominal distension, residuals two times the feeding rate, or diarrhea >2500 ml/day). Meeting >3 of these criteria should “trigger” concern for infection. In this initial assessment of the ABA sepsis criteria correlation with infection, the authors evaluated the ABA sepsis criterias correlation with bacteremia because bacteremia is not associated with inherent issues of diagnosis as occurs with pneumonia or soft tissue infections, and blood cultures are typically obtained due to concern for ongoing infections falling within the definition of “septic.” A retrospective electronic records review was performed to evaluate episodes of bacteremia in the United States Army Institute of Research from 2006 through 2007. A total of 196 patients were admitted during the study period who met inclusion criteria. The first positive and negative cultures, if present, from each patient were evaluated. This totaled 101 positive and 181 negative cultures. Temperature, heart rate, insulin resistance, and feed intolerance criteria were significant on univariate analysis. Only heart rate and temperature were found to significantly correlate with bacteremia on multivariate analysis. The receiver operating characteristic curve area for meeting >3 ABA sepsis criteria is 0.638 (95% confidence interval 0.573–0.704; P < .001). Among severe burn patients, the ABA trigger for sepsis did not correlate strongly with bacteremia in this retrospective chart review.

Computer decision support software safely improves glycemic control in the burn intensive care unit: a randomized controlled clinical study.

The optimal method for glycemic control in the critically burned patient is unknown. The purpose of this randomized controlled study was to determine the safety and efficacy of computer decision support software (CDSS) to control serum glucose concentration in a burn intensive care unit. Eighteen adult burn/trauma patients receiving continuous insulin infusion were initially randomized to receive glucose management by a traditional paper protocol or a computer protocol (CP) for 72 hours and then crossed over to the alternate method for an additional 72 hours. Time in target glucose range (range: 80–110 mg/dl) was higher in the CP group (47 ± 17% vs 41 ± 16.6%; P ≤ .05); time over target range was not significantly reduced in the CP group (49 ± 17.8% vs 54 ± 17.1%; P = .08); and no difference was noted in time under target range of 80 mg/dl (CP: 4.5 ± 2.8%, paper protocol: 4.8 ± 3.3%; P = .8), less than 60 mg/dl (P = .7), and less than 40 mg/dl (P = 1.0). Severe hypoglycemic events (<40 mg/dl) did not differ from the CP group compared with historical controls for patients receiving no insulin (P = .6). More glucose measurements were performed in the CP group (P = .0003), and nursing staff compliance with CP recommendations was greater (P < .0001). Glycemic control using CDSS is safe and effective for the critically burned patient. Time in target range improved without increase in hypoglycemic events. CDSS enhanced consistency in practice, providing standardization among nursing staff.

Glycemic Control in the Burn Intensive Care Unit: Focus on the Role of Anemia in Glucose Measurement

Glycemic control with intensive insulin therapy (IIT) has received widespread adoption secondary to findings of improved clinical outcomes and survival in the burn population. Severe burn as a model for trauma is characterized by a hypermetabolic state, hyperglycemia, and insulin resistance. In this article, we review the findings of a burn center research facility in terms of understanding glucose management. The conferred benefits from IIT, our findings of poor outcomes associated with glycemic variability, advantages from preserved diurnal variation of glucose and insulin, and impacts of glucometer error and hematocrit correction factor are discussed. We conclude with direction for further study and the need for a reliable continuous glucose monitoring system. Such efforts will further the endeavor for achieving adequate glycemic control in order to assess the efficacy of target ranges and use of IIT.

The Impact of Intensive Insulin Protocols and Restrictive Blood Transfusion Strategies on Glucose Measurement in American Burn Association (ABA) Verified Burn Centers

The prevalence of intensive insulin and restrictive blood use protocols in burn centers is unknown, which may be problematic as the combined impact of these therapies is to concomitantly increase the prevalence of anemia and hypoglycemia in intensive care unit patients. Such a development is important because point-of-care (POC) glucometers report erroneously high values in the presence of low hematocrit (HCT), potentially masking the presence of hypoglycemia. We hypothesized that most American Burn Association (ABA) verified burn centers have adopted intensive insulin therapy while simultaneously restricting blood transfusions potentially increasing risk of hypoglycemia. All ABA verified burn centers (N = 44) were contacted. Clinical practices regarding intensive insulin therapy, restrictive transfusion practices, and the use of POC glucometers were evaluated. Intensive insulin protocols were implemented at 73% of ABA centers (defined as upper glucose target of ≤120 mg/dl) and POC glucometers measurement was nearly universal; 95% of ABA centers use them routinely. Anemia is prevalent in intensive care units and may be increasing because of recent changes in practice. Defined hemoglobin and HCT levels trigger blood transfusion at 84% of centers, and of these, 51% restrict transfusion to hemoglobin <7 g/dl or HCT <22%. Most ABA centers now use intensive insulin protocols, many in combination with restrictive transfusion strategies. The combination of a higher prevalence of hypoglycemia in the presence of near universal anemia is concerning, particularly given the pervasiveness of glucometer use among burn centers.