Serum lactate and base deficit suggest inadequate resuscitation of patients with burn injuries: application of a point-of-care laboratory instrument

American Burn Association Clinical Practice Guidelines on Burn Shock Resuscitation

This Clinical Practice Guideline (CPG) addresses the topic of acute fluid resuscitation during the first 48 hours following a burn injury for adults with burns ≥20% of the total body surface area (%TBSA). The listed authors formed an investigation panel and developed clinically relevant PICO (Population, Intervention, Comparator, Outcome) questions. A systematic literature search returned 5978 titles related to this topic and after 3 levels of screening, 24 studies met criteria to address the PICO questions and were critically reviewed. We recommend that clinicians consider the use of human albumin solution, especially in patients with larger burns, to lower resuscitation volumes and improve urine output. We recommend initiating resuscitation based on providing 2 mL/kg/% TBSA burn in order to reduce resuscitation fluid volumes. We recommend selective monitoring of intra-abdominal and intraocular pressure during burn shock resuscitation. We make a weak recommendation for clinicians to consider the use of computer decision support software to guide fluid titration and lower resuscitation fluid volumes. We do not recommend the use of transpulmonary thermodilution-derived variables to guide burn shock resuscitation. We are unable to make any recommendations on the use of high-dose vitamin C (ascorbic acid), fresh frozen plasma (FFP), early continuous renal replacement therapy, or vasopressors as adjuncts during acute burn shock resuscitation. Mortality is an important outcome in burn shock resuscitation, but it was not formally included as a PICO outcome because the available scientific literature is missing studies of sufficient population size and quality to allow us to confidently make recommendations related to the outcome of survival at this time.

Proceedings of the 2021 American Burn Association State and Future of Burn Science Meeting

Periodically, the American Burn Association (ABA) has convened a State of the Science meeting on various topics representing multiple disciplines within burn care and research. In 2021 at the request of the ABA President, meeting development was guided by the ABA's Burn Science Advisory Panel (BSAP) and a subgroup of meeting chairs. The goal of the meeting was to produce both an evaluation of the current literature and ongoing studies, and to produce a research agenda and/or define subject matter-relevant next steps to advance the field(s). Members of the BSAP defined the topics to be addressed and subsequently solicited for nominations of expert speakers and topic leaders from the ABA's Research Committee. Current background literature for each topic was compiled by the meeting chairs and the library then enhanced by the invited topic and breakout discussion leaders. The meeting was held in New Orleans, LA on November 2nd and 3rd and was formatted to allow for 12 different topics, each with two subtopics, to be addressed. Topic leaders provided a brief overview of each topic to approximately 100 attendees, followed by expert-lead breakout sessions for each topic that allowed for focused discussion among subject matter experts and interested participants. The breakout and topic group leaders worked with the participants to determine research needs and associated next steps including white papers, reviews and in some cases collaborative grant proposals. Here, summaries from each topic area will be presented to highlight the main foci of discussion and associated conclusions.

Burn Shock and Resuscitation: Review and State of the Science

Burn shock and acute fluid resuscitation continue to spark intense interest and debate among burn clinicians. Following a major burn injury, fluid resuscitation of burn shock is life-saving, but paradoxically can also be a source of increased morbidity and mortality because of the unintended consequence of systemic edema formation. Considerable research over the past two decades has been devoted to understanding the mechanisms of edema formation, and to develop strategies to curb resuscitation fluids and limit edema development. Recognition of burn endotheliopathy - injury to the endothelium's glycocalyx layer- is one of the most important recent developments in our understanding of burn shock pathophysiology. Newer monitoring approaches and resuscitation endpoints, along with alternative resuscitation strategies to crystalloids alone, such as administration of albumin, or plasma, or high dose ascorbic acid, have had mixed results in limiting fluid creep. Clear demonstration of improvements in outcomes with all of these approaches remains elusive. This comprehensive review article on burn shock and acute resuscitation accompanies the American Burn Association's State of the Science meeting held in New Orleans, LA on November 2-3, 2021 and the Proceedings of that conference published in this journal.

Trend Analysis of Current Modalities for Monitoring Fluid Therapy in Patients With Large Burns: Echoing the Call for Better Resuscitation Indices

The aim of this study was to investigate whether current standards at our institution have effectively monitored resuscitations of severely burned patients during the first 48 hours postburn. Demographics, injuries assessed by TBSA and full thickness (FT), and resuscitation volumes (lactated Ringer's [LR]) were compared for all patients and those who died or survived. Means and standard deviations of hourly indices (urinary output [UOP], lactate [LAC], base excess [BE]) vs LR were analyzed. Waveforms, four-quadrant concordance, and correlation were also employed to compare the trending abilities (hourly changes [∆]) of aforementioned variables vs LR. A total of 203 patients were included in the analysis. Of these patients, 71 (35%) died, and 50 (25%) had inhalation injuries. Mean age and weight were 47 ± 19 years and 87 ± 18 kg, respectively. Mean TBSA burned was 41 ± 20%, with a mean FT of 18 ± 24%. Importantly, normalized waveform plots demonstrated the inability of UO, LAC, and BE to follow hourly changes in LR. Correlation of these variables was weak (r>>-1). This was confirmed by concordance plots. Slopes in all groups demonstrated that UOP was a better resuscitative monitor than LAC or BE. ∆UOP responded to ∆LR better in patients who survived than died. Reliance on hourly UOP as the sole index of optimal resuscitation is not supported. This study echoed the call for better resuscitation indices.

Associations between clinical characteristics and the development of multiple organ failure after severe burns in adult patients

To determine the association between potential risk factors and multiple organ failure (MOF) in severe burn adult patients, we performed a secondary analysis of data from the "Inflammation and the Host Response to Injury" database, which included patients from six burn centers in the United States between 2003 and 2009. Three hundred twenty-two adult patients (aged ≥16 years) with severe burns (≥20.0% total body surface area [TBSA]) were included. MOF was defined according to the Denver score. Potential risk factors were analyzed for their association with MOF. Models were built using multivariable logistic regression analysis. Eighty-eight patients (27.3%) developed MOF during the study period. We found that TBSA, age, and inhalation injury were significant risk factors for MOF. This predictive model showed good performance, with the total area under the receiver operating characteristic curve being 0.823. Moreover, among patients who developed MOF, inhalation injury was significantly associated with the development of MOF in the acute phase (within three days of injury) (adjusted odds ratio 3.1; 95% confidence interval 1.1-8.3). TBSA, age, lactate, and Denver score within 24h were associated with the late phase development of MOF. Thus, we have identified key risk factors for the onset of MOF after severe burn injury. Our findings contribute to the understanding of individualized treatment and will potentially allow for efficient allocation of resources and a lower threshold for admission to an intensive care unit, which can prevent the development of MOF and eventually reduce mortality.

Volume Resuscitation in Patients With High-Voltage Electrical Injuries

Volume resuscitation of patients with high-voltage electrical injuries (>1000 V) is a more complex challenge than standard burn resuscitation. High voltages penetrate deep tissues. These deep injuries are not accounted for in resuscitation formulae dependent on percentage of cutaneous burn. Myonecrosis occurring from direct electrical injury and secondary compartment syndromes can result in rhabdomyolysis, compromising renal function and urine output. Urine output is the primary end point, with a goal of 1 mL/kg/h for adult patients with high-voltage electrical injuries. As such, secondary resuscitation end points of laboratory values, such as lactate, base deficit, hemoglobin, and creatinine, as well as hemodynamic monitoring, such as mean arterial pressure and thermodilution techniques, can become crucial in guiding optimum administration of resuscitation fluids. Mannitol and bicarbonates are available but have limited support in the literature. High-voltage electrical injury patients often develop acute kidney injury requiring dialysis and have increased risks of chronic kidney disease and mortality. Continuous venovenous hemofiltration is a well-supported adjunct to clear the myoglobin load that hemodialysis cannot from circulation.

Burn State of the Science: Fluid Resuscitation

Recognition of fluid creep has driven a large amount of the scientific investigation in the area of acute fluid resuscitation for burn patients. The role of colloids in ameliorating fluid creep is controversial, despite the fact that a fluid-sparing effect of colloids has been recognized for some time. All but one of the available prospective studies using colloids are more than a decade old, and a modern randomized controlled trial (RCT) comparing crystalloids to colloids is long overdue. While urinary output continues to be the main endpoint for fluid titration, there has been a moderate amount of interest in the use of transpulmonary thermodilution to guide fluid resuscitation. The available studies have found that transpulmonary thermodilution has had an inconsistent effect on limiting fluid resuscitation volumes and improving clinical outcomes. Computerized Decision Support Systems show great promise in optimizing fluid titration and reducing fluid resuscitation volumes, and an RCT comparing Computerized Decision Support Systems with conventional titration approaches will be the important next step. Use of high-dose vitamin C (ascorbic acid) has become a popular approach to limit fluid resuscitation volumes and edema formation, but it has been investigated in only two clinical studies: one a pseudo-randomized prospective study and the other a retrospective study. Improvements in clinical outcome have not been convincingly demonstrated, and concerns persist surrounding the possibility of induction of an osmotic diuresis, leading to intravascular volume depletion. An RCT is urgently required to evaluate high-dose vitamin C as an adjunct to crystalloid resuscitation compared with the use of crystalloids alone.

Strong ion gap is associated with mortality in pediatric burn injuries

Severe burn injury produces significant tissue damage, resulting in metabolic acidosis. Current methods of acid-base evaluation are based on dependent variables that may not be accurate after burn injury. The strong ion method of acid-base evaluation is based on independent variables and may accurately predict outcomes in severely burn-injured patients. The authors hypothesize that an increased strong ion gap present on admission will be associated with mortality in severely burn-injured pediatric patients. A retrospective chart review was performed of burn-injured pediatric patients with a TBSA 20% or greater. Data collected included age, TBSA burn injury, mechanism of injury, survival, ventilator days, hospital length of stay, intensive care unit length of stay, and admission laboratory values. Apparent and effective strong ion difference (SIDa, SIDe) were calculated. The strong ion gap (SIG) was determined as the difference between SIDa and SIDe. A total of 48 patients were included in the study. Mean age (years) and TBSA were 7.9 ± 0.8 years and 56.8 ± 2.6%. Eleven patients (23%) died. Mean TBSA for survivors (54.2 ± 2.9%) did not significantly differ from that of nonsurvivors (65.7 ± 5.34%). Ten patients suffered inhalation injury, which was associated with an odds ratio of 10.1* for mortality. Mean SIDa was 44.2 ± 3.2 for the entire study population. Survivors had a significantly lower SIDa (36.6 ± 0.5) than nonsurvivors (59.7 ± 13*). Mean SIDe for all patients was (25 ± 0.7) and did not differ significantly between survivors (24.7 ± 0.7) and nonsurvivors (25.8 ± 2). SIG for nonsurvivors (33.91 ± 14*) was significantly higher than for survivors (14.9 ± 0.3). Controlling for both TBSA and inhalation injury, death was associated with both an increased SIDa (B = 19.3*) and SIG (B = 17.3*). SIG is increased in severely burn-injured pediatric patients, indicating the presence of metabolic acidosis. Furthermore, an increased SIG is significantly associated with mortality. (*P <.05.).

Academic College of Emergency Experts in India's INDO-US Joint Working Group and OPUS12 Foundation Consensus Statement on Creating A Coordinated, Multi-Disciplinary, Patient-Centered, Global Point-of-Care Biomarker Discovery Network

Biomarker science brings great promise to clinical medicine. This is especially true in the era of technology miniaturization, rapid dissemination of knowledge, and point-of-care (POC) implementation of novel diagnostics. Despite this tremendous progress, the journey from a candidate biomarker to a scientifically validated biomarker continues to be an arduous one. In addition to substantial financial resources, biomarker research requires considerable expertise and a multidisciplinary approach. Investigational designs must also be taken into account, with the randomized controlled trial remaining the “gold standard”. The authors present a condensed overview of biomarker science and associated investigational methods, followed by specific examples from clinical areas where biomarker development and/or implementation resulted in tangible enhancements in patient care. This manuscript also serves as a call to arms for the establishment of a truly global, well-coordinated infrastructure dedicated to biomarker research and development, with focus on delivery of the latest discoveries directly to the patient via point-of-care technology.

Differences in resuscitation in morbidly obese burn patients may contribute to high mortality

The rising number of obese patients poses new challenges for burn care. These may include adjustments in calculations of burn size, resuscitation, ventilator wean, nutritional goals as well as challenges in mobilization. The authors have focused this observational study on resuscitation in the obese patient population in the first 48 hours after burn injury. Previous trauma studies suggest a prolonged time to reach end points of resuscitation in the obese compared to nonobese injured patients. The authors hypothesize that obese patients have worse outcomes after thermal injury and that differences in the response to resuscitation contribute to this disparity. The authors retrospectively analyzed data prospectively collected in a multicenter trial to compare resuscitation and outcomes in patients stratified by National Institutes of Health/World Health Organization body mass index (BMI) classification (BMI: normal weight, 18.5-24.9; overweight, 25-29.9, obese, 30-39.9; morbidly obese, ≥40). Because of the distribution of body habitus in the obese, total burn size was recalculated for all patients by using the method proposed by Neaman and compared with Lund-Browder estimates. The authors analyzed patients by BMI class for fluids administered and end points of resuscitation at 24 and 48 hours. Multivariate analysis was used to compare morbidity and mortality across BMI groups. The authors identified 296 adult patients with a mean TBSA of 41%. Patient and injury characteristics were similar across BMI categories. No significant differences were observed in burn size calculations by using Neaman vs Lund-Browder formulas. Although resuscitation volumes exceeded the predicted formula in all BMI categories, higher BMI was associated with less fluid administered per actual body weight (P = .001). Base deficit on admission was highest in the morbidly obese group at 24 and 48 hours. Furthermore, the morbidly obese patients did not correct their metabolic acidosis to the extent of their lower BMI counterparts (P values .04 and .03). Complications and morbidities across BMI groups were similar, although examination of organ failure scores indicated more severe organ dysfunction in the morbidly obese group. Compared with being normal weight, being morbidly obese was an independent risk factor for death (odds ratio = 10.1; confidence interval, 1.94-52.5; P = .006). Morbidly obese patients with severe burns tend to receive closer to predicted fluid resuscitation volumes for their actual weight. However, this patient group has persistent metabolic acidosis during the resuscitation phase and is at risk of developing more severe multiple organ failure. These factors may contribute to higher mortality risk in the morbidly obese burn patient.

Strong ion difference and gap predict outcomes after adult burn injury

BACKGROUND

The strong ion difference (SID) (apparent [SIDa] and effective [SIDe]) and strong ion gap (SIG) provide a comprehensive method of evaluating acid-base status in critically ill patients. The SID is the difference between strong cations and strong anions in plasma, while the SIG demonstrates the presence of unmeasured ions. This approach accounts for changes in a patient's protein status, which is particularly important in those with burn injuries. We hypothesized that the SIDa, SIDe, and SIG during the first 72 hours after admission would be predictive of mortality in burn patients.

METHODS

This study is a retrospective review of adults with 20% or greater total body surface area burns admitted during a 7-year period to a regional burn center. SIDa, SIDe, and SIG were calculated at admission and for the first 3 days. These results were then compared with Acute Physiology and Chronic Health Evaluation II (APACHE II) and sepsis-related organ failure assessment (SOFA) scores.

RESULTS

A total of 113 patients met the criteria and had full data sets, with mean ± SEM age of 45.4 ± 1.4 years and total body surface area burn of 41.4% ± 1.6%. Mortality was 27.4%. At admission, APACHE II remained most predictive of mortality (p = 0.006). However, admission SIG (SIDa - SIDe) was also predictive of mortality on multivariate analysis (odds ratio, 1.11). Day 1 SIDa (Na+ + K+ + Ca2+ + Mg2+ - Cl-) and SIDe ([1,000 × 2.46 × 10(-11) × PaCO2/10(-pH)] + [[albumin] × (0.123 × pH - 0.631)] + [[PO4] × (0.309) × pH - 0.469)]) were also associated with mortality (odds ratio, 1.16 and 1.13 respectively), and SIDe with length of stay and ventilator days (p < 0.05).

CONCLUSION

The SID and SIG are predictive of mortality, hospital length of stay, and ventilator days in adult burn patients. They also elucidate complex acid-base disorders.

LEVEL OF EVIDENCE

Prognostic study, level II.

Clinical review: the critical care management of the burn patient

Between 4 and 22% of burn patients presenting to the emergency department are admitted to critical care. Burn injury is characterised by a hypermetabolic response with physiologic, catabolic and immune effects. Burn care has seen renewed interest in colloid resuscitation, a change in transfusion practice and the development of anti-catabolic therapies. A literature search was conducted with priority given to review articles, meta-analyses and well-designed large trials; paediatric studies were included where adult studies were lacking with the aim to review the advances in adult intensive care burn management and place them in the general context of day-to-day practical burn management.

Severe burn injury, burn shock, and smoke inhalation injury in small animals. Part 2: diagnosis, therapy, complications, and prognosis

OBJECTIVE

To review the evaluation and treatment of patients suffering from severe burn injury (SBI), burn shock, and smoke inhalation injury. Potential complications and prognosis associated with SBI are also discussed.

DIAGNOSIS

Diagnosis of burn injury and burn shock is based on patient history and clinical presentation. Superficial burn wounds may not be readily apparent for the first 48 h whereas more severe wounds will be evident at presentation. Patients are diagnosed with local or SBI by estimating total body surface area involved using the 'Rule of Nines' or the Lund-Browder chart adapted from the human literature.

THERAPY

Patients suffering from SBI require immediate and aggressive fluid therapy. Burn wounds require prompt cooling to prevent progressive tissue damage. Due to significant pain associated with burn wounds and therapeutic procedures, multimodal analgesia is recommended. Daily wound management including hydrotherapy, topical medications, and early wound excision and grafting is necessary with SBI.

COMPLICATIONS

There are numerous complications associated with SBI. The most common complications include infections, hypothermia, intra-abdominal hypertension, and abdominal compartment syndrome.

PROGNOSIS

The prognosis of SBI in domestic animals is unknown. Based on information derived from human literature, patients with SBI and concomitant smoke inhalation likely have a worse prognosis than those with SBI or smoke inhalation alone.

Predicting acute kidney injury among burn patients in the 21st century: a classification and regression tree analysis

Historically, acute kidney injury (AKI) carried a deadly prognosis in the burn population. The aim of this study is to provide a modern description of AKI in the burn population and to develop a prediction tool for identifying patients at risk for late AKI. A large multi-institutional database, the Glue Grant's Trauma-Related Database, was used to characterize AKI in a cohort of critically ill burn patients. The authors defined AKI according to the RIFLE criteria and categorized AKI as early, late, or progressive. They then used Classification and Regression Tree (CART) analysis to create a decision tree with data obtained from the first 48 hours of admission to predict which subset of patients would develop late AKI. The accuracy of this decision tree was tested in a separate, single-institution cohort of burn patients who met the same criteria for entry into the Glue Grant study. Of the 220 total patients analyzed from the Glue Grant cohort, 49 (22.2%) developed early AKI, 39 (17.7%) developed late AKI, and 16 (7.2%) developed progressive AKI. The group with progressive AKI was statistically older, with more comorbidities and with the worst survival when compared with those with early or late AKI. Using CART analysis, a decision tree was developed with an overall accuracy of 80% for the development of late AKI for the Glue Grant dataset. The authors then tested this decision tree on a smaller dataset from our own institution to validate this tool and found it to be 73% accurate. AKI is common in severe burns with notable differences between early, late, and progressive AKI. In addition, CART analysis provided a predictive model for early identification of patients at highest risk for developing late AKI with proven clinical accuracy.

Evaluation of acid-base balance in ST-elevation myocardial infarction in the early phase: a prognostic tool?

OBJECTIVES

Metabolic acidosis has been described after myocardial infarction, but little data are available on the acid-base imbalance in ST-elevation myocardial infarction (STEMI) submitted to mechanical revascularization, and earlier studies on this topic differ with respect to patients' selection criteria, treatment and evaluated parameters.

METHODS

We assessed admission base excess, anion gap, and lactate in 445 consecutive patients with STEMI submitted to primary percutaneous coronary intervention and whether its evaluation could help in identifying patients at a higher risk for in-hospital mortality and complications (acute pulmonary edema and arrhythmias).

RESULTS

At backward stepwise logistic regression analysis, the following variables were independently associated with intra-ICCU mortality: age [odds ratio (OR) 1.05; 95% confidence interval (CI) 1.02-1.10; P = 0.006], estimated glumerular filtration rate (OR 0.98; 95% CI 0.96-0.99; P= 0.010), Tn I (OR 1.006; 95% CI 1.004-1.008; P <0.001), and base excess (OR 0.90; 95% CI 0.82-0.99; P = 0.038); Hosmer-Lemeshow v2: 5.69, P = 0.681. At backward stepwise logistic regression analysis, the following variables were independently associated with intra-ICCU complications: left ventricular ejection fraction (OR 0.95; 95% CI 0.91-0.98; P = 0.005) and lactic acid (OR 1.31; 95% CI 1.10-1.57; P =0.003); Hosmer-Lemeshow v2: 4.11, P = 0.847.

CONCLUSION

According to our findings, the evaluation of base excess and lactate in the early phase of STEMI provides the bedside clinicians with useful tools for early risk stratification. In fact, base excess proved to be an independent predictor for intra-ICCU mortality, whereas lactate represented an independent marker for intra-ICCU complications.

Early acute kidney injury predicts progressive renal dysfunction and higher mortality in severely burned adults

The incidence and prognosis of acute kidney injury (AKI) developing during acute resuscitation have not been well characterized in burn patients. The recently developed Risk, Injury, Failure, Loss, and End-stage (RIFLE) classification provides a stringent stratification of AKI severity and can allow for the study of AKI after burn injury. We hypothesized that AKI frequently develops early during resuscitation and is associated with poor outcomes in severely burned patients. We conducted a retrospective review of patients enrolled in the prospective observational multicenter study "Inflammation and the Host Response to Injury." A RIFLE score was calculated for all patients at 24 hours and throughout hospitalization. Univariate and multivariate analyses were performed to distinguish the impact of early AKI on progressive renal dysfunction, need for renal replacement therapy, and hospital mortality. A total of 221 adult burn patients were included, with a mean TBSA burn of 42%. Crystalloid resuscitation averaged 5.2 ml/kg/%TBSA, with urine output of 1.0 +/- 0.6 ml/kg/hr at 24 hours. Sixty-two patients met criteria for AKI at 24 hours: 23 patients (10%) classified as risk, 32 patients (15%) as injury, and 7 (3%) as failure. After adjusting for age, TBSA, inhalation injury, and nonrenal Acute Physiology and Chronic Health Evaluation II > or =20, early AKI was associated with an adjusted odds ratio 2.9 for death (95% CI 1.1-7.5, P = .03). In this cohort of severely burned patients, 28% of patients developed AKI during acute resuscitation. AKI was not always transient, with 29% developing progressive renal deterioration by RIFLE criteria. Early AKI was associated with early multiple organ dysfunction and higher mortality risk. Better understanding of how early AKI develops and which patients are at risk for progressive renal dysfunction may lead to improved outcomes.

Critical care of the burn patient: the first 48 hours

OBJECTIVE

The goal of this concise review is to provide an overview of some of the most important resuscitation and monitoring issues and approaches that are unique to burn patients compared with the general intensive care unit population.

STUDY SELECTION

Consensus conference findings, clinical trials, and expert medical opinion regarding care of the critically burned patient were gathered and reviewed. Studies focusing on burn shock, resuscitation goals, monitoring tools, and current recommendations for initial burn care were examined.

CONCLUSIONS

The critically burned patient differs from other critically ill patients in many ways, the most important being the necessity of a team approach to patient care. The burn patient is best cared for in a dedicated burn center where resuscitation and monitoring concentrate on the pathophysiology of burns, inhalation injury, and edema formation. Early operative intervention and wound closure, metabolic interventions, early enteral nutrition, and intensive glucose control have led to continued improvements in outcome. Prevention of complications such as hypothermia and compartment syndromes is part of burn critical care. The myriad areas where standards and guidelines are currently determined only by expert opinion will become driven by level 1 data only by continued research into the critical care of the burn patient.

The phenomenon of "fluid creep" in acute burn resuscitation

Several reports have documented that modern burn patients receive far more resuscitation fluid than predicted by the Parkland formula-a phenomenon termed "fluid creep." This article reviews the incidence, consequences, and possible etiologies of fluid creep in modern practice and uses this information to propose some therapeutic strategies to reduce or eliminate excessive fluid resuscitation in burn care. A literature review was performed of historical references that form the foundation of modern fluid resuscitation, as well as reports of fluid creep and its consequences. The original Parkland formula required a 24-hour volume of 4 ml/kg/%TBSA lactated Ringer's solution followed by an infusion of 0.3-0.5 ml/kg/ %TBSA plasma. Modern iterations of this formula have omitted the colloid bolus. Numerous exceptions to the formula have been noted, most consistently patients with inhalation injuries. In contrast, recent reports document greatly increased fluid requirements in unselected patients, which seems to consist largely of progressive edema formation in unburned areas, increasing after the first 8 hours post-burn. This has been linked to occurrence of the abdominal compartment syndrome and other serious complications. Strategies to reduce fluid creep include the avoidance of early overresuscitation, use of colloid as a routine component of resuscitation or for "rescue," and adherence to protocols for fluid resuscitation. Fluid creep is a significant problem in modern burn care. Review of original investigations of burn shock, coupled with modern reports of fluid creep, suggests several mechanisms by which this problem can be controlled. Prospective trials of these therapies are needed to confirm their effectiveness.

The association between fluid administration and outcome following major burn: a multicenter study

OBJECTIVE

To determine patient and injury variables that influence fluid requirements following burn injury and examine the association between fluid volume received and outcome.

BACKGROUND

Fluid resuscitation remains the cornerstone of acute burn management. Recent studies suggest that patients today are receiving more fluid per percent total body surface area (TBSA) than in the past. Therefore, there is a need to better define the factors that impact fluid requirements and to determine the effects of fluid volumes on outcome.

METHODS

This study was part of a federally funded multicenter study. Multilinear regression analyses were performed to determine the patient and injury characteristics that most influenced fluid resuscitation volumes received. To assess the association of fluid volumes on outcome, propensity scores were developed to provide a predicted volume of fluid for each patient. Logistic models were then used to assess the impact of excess fluid beyond predicted volumes on outcome.

RESULTS

Seventy-two patients were included in this analysis. Average patient age was 40.6 years and average TBSA was 44.5%. Average fluid volume received during the first 24 hours after injury was 5.2/mL/kg/TBSA. Significant predictors of fluid received included % TBSA, age, intubation status, and weight. Increased fluid volume received increased risk of development of pneumonia (odds ratio [OR] = 1.92), bloodstream infections (OR =2.33), adult respiratory distress syndrome (OR = 1.55), multiorgan failure (OR= 1.49), and death (OR = 1.74).

CONCLUSION

TBSA, age, weight, and intubation status on admission were significant predictors of fluid received. Patients who received larger volumes of resuscitation fluid were at higher risk for injury complications and death.

The Relationship of Serum Lactate and Base Deficit in Burn Patients to Mortality

Serum lactate and base deficit in trauma patients have been shown to correlate with mortality. This study examines the relationship of these parameters to mortality among burn patients. We evaluated patients with >or=20% TBSA burn injury who had a serum lactate or base deficit recorded during the initial 48 hours of admission over a 5-year period. The primary study outcome was mortality. The mean (+/-SD) age of study patients (N = 128) was 35.2 +/- 21.1 years, the mean burn size was 41.7 +/- 17.9% TBSA, and the mortality rate was 17.1%. Mean serum lactate values of patients who died were significantly higher than those of survivors at admission and at 12, 18, and 24 hours after admission. The highest serum lactate value in the first 48 hours after admission was higher for nonsurvivors than survivors. Mean base deficit at admission and 6 hours after admission was significantly lower in patients who died than in survivors; in addition, the worst base deficit during the first 48 hours of care was significantly lower in patients who died than in those who survived. Early serum lactate and base deficit values are often worse for burn patients who die than for survivors. Elevation of serum lactate values during the first 48 hours after a burn is an independent risk factor for death, but no threshold value for serum lactate is demonstrable. Resuscitation should not be withheld from burn patients on the basis of any lactate or base deficit value.

Burn patient characteristics and outcomes following resuscitation with albumin

BACKGROUND

Use of colloids in acute burn resuscitation may reduce fluid requirements, but effect on mortality is unknown. We hypothesized that patients who received albumin would have similar mortality to patients who did not receive albumin.

METHODS

We performed a case-controlled study of inpatients who sustained burns of > or =20% total body surface area (TBSA). Patients who received albumin during resuscitation because of increased fluid requirements (ALB) were compared to a cohort of patients matched for age and TBSA who did not receive albumin (CON).

RESULTS

Patients with inhalation injury were significantly more likely to receive albumin (OR 4.89, 95% CI 2.58-9.30). ALB patients had significantly higher mean initial lactate (3.64 versus 2.29, p=0.01), longer mean time to resuscitation (52.8 h versus 36.3 h; p=0.001), and higher resuscitation volume (9.4 mL/kg/%TBSA versus 6.4 mL/kg/%TBSA for CON). Mortality was not significantly different between the two groups (OR 1.90, 95% CI 0.85-4.22). Albumin was protective in a multivariate model of mortality (OR 0.27, 95% CI 0.07-0.97).

CONCLUSIONS

Despite more severe systemic dysfunction, burn patients who received albumin did not suffer increased mortality. A novel finding is the decreased likelihood of mortality associated with the administration of albumin during burn resuscitation.

Base deficit and alveolar-arterial gradient during resuscitation contribute independently but modestly to the prediction of mortality after burn injury

The main determinants of mortality after burn injury that can be measured on admission include age, total burn size (% burn), and inhalation injury (INHAL). Other variables, measured during resuscitation, may provide additional information about injury severity. We assessed the utility of early arterial blood gas (ABG) data in predicting mortality after burn injury. Data were limited to samples obtained during the first 2 days after burn injury and to those obtained during high-frequency percussive ventilation. Mean values for each patient's ABG data were calculated; subsequent analysis used these derived variables. Logistic regression analysis (LRA) was used to generate a mortality predictor using burn, age (as a cubic age score, AGE), and INHAL. LRA was then repeated with the ABG variables. A total of 162 patients were included. By univariate analysis, death was associated with increased alveolar-arterial gradient (AaDO2), AGE, % burn, full-thickness burn size, INHAL, and with decreased pH and base excess. LRA of % burn, AGE, INHAL, and full-thickness burn size retained the first three variables. The addition of ABG data demonstrated that mean burn excess and mean AaDO2 also contributed independently to mortality. However, there was no difference in accuracy (86%) between the two equations. By Kaplan Meier analysis, AaDO2 but not BE predicted earlier death in those who died. Measured during resuscitation, metabolic acidosis (ie, a base deficit) and oxygenation failure (ie, increased AaDO2) contributed independently, but modestly, to ultimate mortality after burn injury. The inclusion of these variables did not improve predictive accuracy. Whether therapies targeted at these endpoints would improve outcome is unknown.

The 2003 Carl A Moyer Award: real-time metabolic monitors, ischemia-reperfusion, titration endpoints, and ultraprecise burn resuscitation

Real-time metabolic monitoring of varied vascular beds provides the raw data necessary to conduct ultraprecise burn shock resuscitation based on second-by-second assessment of regional tissue perfusion. It also illustrates shortcomings of current clinical practices. Arterial base deficit was continuously monitored during 11 clinical resuscitations of patients suffering burn shock using a Paratrend monitor. Separately, in a 30% TBSA rat burn model (N = 70), three Paratrend monitors simultaneously recorded arterial blood gas and tissue pCO2 of the burn wound and colonic mucosa during resuscitation at 0, 2, 4, 6, and 8 ml/kg/%TBSA. Paratrend data were analyzed in conjunction with previously reported laser Doppler images of actual burn wound capillary perfusion. With current clinical therapy, continuous monitoring of arterial base deficit revealed repetitive cycles of resolution/worsening/resolution during burn shock resuscitation. In the rat model, tissue pCO2 in both burn wounds and splanchnic circulation differed depending on the rate of fluid resuscitation (P <.01 between sham and 0 ml/kg/%TBSA and between 2 ml/kg/%TBSA and 4 ml/kg/%TBSA). Burn wound pCO2 values correlated well with laser Doppler determination of actual capillary perfusion (rho = -.48, P <.01). The following conclusions were reached: 1). Gratuitous and repetitive ischemia-reperfusion-ischemia cycles plague current clinical therapy as demonstrated by numerous "false starts" in the resolution of arterial base deficit; 2). in a rat model, real-time monitoring of burn wound and splanchnic pCO2 demonstrate a dose-response relationship with rate of fluid administration; and 3). burn wound and splanchnic pCO2 are highly correlated with direct measurement of burn wound capillary perfusion by laser Doppler imager. Either technique can serve as a resuscitation endpoint for real-time feedback-controlled ultraprecise resuscitation.

Predicting increased fluid requirements during the resuscitation of thermally injured patients

BACKGROUND

We determined whether factors present soon after burn predict which patients will receive more than 4 mL/kg/% burn during the first 24 hours, and whether total fluid intake during the first 24 hours (VOL) contributes to in-hospital mortality (MORT).

METHODS

We reviewed the records of patients admitted during 1987-97. The modified Brooke resuscitation formula was used. One hundred four patients met inclusion criteria: total body surface area burned (TBSA) > or = 20%; admission directly from the field; weight > 30 kg; no electric injury, mechanical trauma, or blood transfusions; and survival > or = 24 hours postburn. Eighty-nine records were complete.

RESULTS

Mean TBSA was 43%, mean full-thickness burn size was 21%, mean age was 41 years, mean VOL was 4.9 mL/kg/% burn, and mean lactated Ringer's volume was 4.4 mL/kg/% burn; 53% had inhalation injury. MORT was 25.8%. Mean urine output was 0.77 mL/kg/h. By linear regression, VOL was associated with weight (negatively) and full-thickness burn size (r2 = 0.151). By logistic regression, receipt of over 4 mL/kg/% burn was predicted at admission by weight (negatively) and TBSA; by 24 hours postburn, mechanical ventilation replaced TBSA. With respect to MORT, logistic regression of admission factors yielded a model incorporating TBSA and an age function; by 24 hours postburn, the worst base deficit was added.

CONCLUSION

Burn size and weight (negatively) were associated with greater VOL. However, a close linear relationship between burn size and VOL was not observed. Mechanical ventilation supplanted TBSA by 24 hours as a predictor of high VOL. Worst base deficit, TBSA, and an age function, but not VOL, were predictors of MORT.

Trends in burn resuscitation: shifting the focus from fluids to adequate endpoint monitoring, edema control, and adjuvant therapies

Bum shock is a complex process involving a series of intertwined physiologic responses to injury that require more rigorous intervention than simply a change in fluid tonicity, fluid composition, or fluid resuscitation volume. Controversy ensues over monitoring techniques and resuscitation goals, in part because the identification of true markers of perfusion is clouded by intradependence of endpoints on other metabolic processes. The persistence of cellular hypoperfusion in patients who have been deemed adequately resuscitated by global indices supports the growing realization that failure of conventional endpoint-monitoring strategies to detect compensated bum shock can lead to significant organ injury from SIRS or MODS. Current endpoints should be interpreted in the aggregate, because none have yet been demonstrated to reflect tissue perfusion status independently and accurately. Numerous technologically advanced endpoints to predict patient outcome, which may be useful in determining futility of treatment or end-of-life decisions, are now available. Still lack-ing, however, is a reliable tool proven to improve outcome that can guide bum shock resuscitation therapies successfully. Exciting new research in tissue oxygenation and perfusion has revealed that damaging mediator cascades and irreversible microvascular changes may preclude complete resolution of bum shock solely through restoration of oxygen delivery. Because bum patients now frequently survive the early resuscitation phase. the focus should be on controlling derangements in oxygen use and correcting occult hypoperfusion to reduce later adverse patient outcomes from SIRS, sepsis, and MODS. Bum-specific research on resuscitation endpoints and monitoring strategies lags behind research in other patient populations. Present standards and monitoring guidelines for bum shock resuscitation should be critically evaluated and based on true, scientifically validated data rather than on observational studies or personal beliefs. Thus the continuing challenge for clinicians and researchers:burn centers must collaborate to perform large, multi-center studies to evaluate critically and to prove resuscitation endpoints and therapies. Future technologies targeted at microcirculatory perfusion and cellular oxygenation offer an exciting promise for less invasive, easily accessible, more accurate endpoints and treatments for bum shock resuscitation.

Role of Vernix Caseosa in the Neonate

Vernix caseosa is a naturally occurring fetal barrier film produced in late pregnancy as a result of sebaceous and epidermal lipids combined with desquamation of maturing fetal corneocytes. Vernix lacks desmosomal interconnections between corneocytes as demonstrated in adult stratum corneum and is, therefore, referred to as a "mobile phase" stratum corneum. Vernix is proposed to have multiple fetal/newborn overlapping biological functions: moisturization, anti-infective, antioxidant, wound healing, and waterproofing. Patients with altered skin integrity due to burn injuries lack the protective qualities necessary for wound healing. Emerging research suggests that Vernix applied to skin cultures may enhance wound healing. Application of the fetal/neonatal skin science findings to the adult burn population offers the potential for a clinically relevant homologous substitute for impaired tissue integrity.

Modelo experimental de choque hemorrágico

OBJETIVO: É estabelecer um modelo experimental de choque hemorrágico, reproduzindo o mais próximo possível uma real situação que ocorre nas vítimas traumatizadas. MÉTODOS: Utilizou-se 16 animais, distribuídos aleatoriamente em 2 grupos (n=8): Grupo Controle (GC): procedimentos cirúrgicos e observação de 60 minutos; Grupo Choque (GCh): procedimentos cirúrgicos, sangria para estabelecimento do estado de choque (EC) com pressão arterial média (PAM) em 40 mmHg, mantido por 20 minutos (20') seguido de período de reperfusão de 60 minutos (RP60). Para avaliar o EC estabelecido, além da PAM, utilizaram-se os seguintes parâmetros: lactato sérico (LS) e diferença de base (DB). Na instalação do EC, iniciou-se com retirada de volume de sangue correspondente a 5% da volemia estimada até atingir PAM de 60mmHg, ponto do qual as retiradas passaram para 2,5%. RESULTADOS: Após o período de 20' do EC o LS médio do GC foi de 0,92 mmol/l e do GCh foi de 4,16 mmol/l. A DB média do GC foi de 0,02 mmol/l e do GCh foi de 8, 12 mmol/l. CONCLUSÃO: As alterações resultantes do processo de instalação e reanimação do EC mostraram uma relação inversamente proporcional entre LS e DB, fato que confirma a má perfusão tecidual e restauração volêmica dentro do presente modelo experimental.

A prospective study on the implications of a base deficit during fluid resuscitation

An excessive base deficit (BD) and elevated serum lactate are increasingly recognized as important markers of a malperfusion state during the resuscitation of thermally injured patients. In a previous retrospective study, we found that patients with a BD less than -6 mmol/l during fluid resuscitation developed more severe systemic inflammatory response syndrome (SIRS), more frequent acute respiratory distress syndrome (ARDS), and more severe multiple organ dysfunction syndrome (MODS). The object of this study was to reexamine prospectively the relationship between the BD during fluid resuscitation and the subsequent development of SIRS, ARDS, and MODS by undertaking a prospective observational study of a cohort of consecutive burn patients. Analysis was completed on 38 patients with a mean age of 39 +/- 17 years and a mean %TBSA burn of 36 +/- 15%. The mean BD in the first 24 hours was less than -6 mmol/l in five patients (BD24 < -6 group), and was greater than -6 mmol/L in 33 patients (BD24 > -6 group). Patients in both groups were resuscitated to nearly identical endpoints of urinary output (1.2 ml/kg/hr in the BD24 < -6 group vs 1.3 ml/kg/hr in the BD24 > -6 group). Patients in the BD24 < -6 group had a trend toward a greater number of SIRS signs on the first postburn day, had a significantly higher incidence of ARDS (P =.02), and had significantly more severe MODS (P <.001) than patients in the BD24 > -6 group. The results concur with those of our previous retrospective study. Despite resuscitation to an acceptable urinary output, some burn patients develop a more extreme BD and go on to experience more severe organ dysfunction than do patients who do not generate a BD. The effect of specific correction of the BD during fluid resuscitation is not known at this time.

Base deficit does not predict mortality when secondary to hyperchloremic acidosis

Base deficit has been established as a predictor of mortality and endpoint of resuscitation. We hypothesized that in a significant subset of surgical intensive care patients, base deficit is secondary to hyperchloremic acidosis, and that these patients experience lower mortality than those patients whose base deficits are secondary to other causes. Seventy-five consecutive surgical intensive care patients with base deficits greater than 2.0 were prospectively studied. The etiology of the patients' base deficits was determined by admission laboratory data. Patients were divided into those with hyperchloremic acidosis, and those with acidosis from other causes. Mortality within these groups was compared by Fisher's exact test. Thirty-seven patients (49.3%) had hyperchloremic acidosis. Thirty-three patients (46.7%) had lactic acidosis. Three patients (4%) had base deficits secondary to ketosis, and two patients (2.6%) had base deficits secondary to uremia. There were no significant differences in age, APACHE II scores, or volumes of resuscitation between the hyperchloremic group and the remaining patients. There were four deaths (10.8%) in the hyperchloremic group and thirteen deaths (34.2%) in the remaining patients (P = 0.03). Hyperchloremic acidosis resulted from resuscitation with lactated Ringer's solution in 18 (48.6%) of the hyperchloremic patients. Hyperchloremic acidosis is a common etiology of base deficit in the surgical intensive care unit. It is associated with lower mortality than base deficit secondary to other causes. Moreover, it is frequently induced following resuscitation with lactated Ringer's solution. Failure to properly diagnose this subset of acidotic patients may result in inappropriate clinical interventions due to the erroneous presumption of ongoing tissue hypoxia.

Serum lactate, not base deficit, rapidly predicts survival after major burns

BACKGROUND

Clinical studies document correlation of serum lactate and base deficit with mortality in trauma and sepsis. No study of the prognostic value of these two serum markers has been reported in burn injury.

METHODS

Resuscitation data from 49 patients admitted to the adult Burn ICU were analyzed. Lactate and base deficit were analyzed upon admission and every 2h during the initial 48 h after admission. Resuscitation was managed per standard routine, blinded to these data, guided by the Parkland formula. Initial statistical analysis with Cox's regression model was used to determine the relationship between survival, resuscitation parameters, and demographics. Then, a logistic regression was used to determine if any of these variables were quickly predictive (initial values) of the risk of death.

RESULTS

Two variables were predictive of mortality by the Cox regression model: (1) serum lactate value and (2) patient age. Furthermore, analysis by logistic regression revealed that the initial serum lactate value was separately predictive of mortality.

CONCLUSION

In this study, serum lactate but not base deficit, was a predictor of mortality following major burns. Moreover, initial serum lactate values were also predictive of mortality separately.

Microvascular assessment of burn depth conversion during varying resuscitation conditions

Conversion of partial- to full-thickness injuries, even after the burning has stopped, remains a significant clinical problem. We developed a rat model with a wide range of burn depths to study this phenomenon by microvascular assessment. Fifty-four male Sprague-Dawley rats weighing 460 g on average were studied. Real-time tissue monitoring of pH, paCO2, and paO2 was achieved by placement of a continuous blood gas monitor transducer in the aorta. Ten, 2-cm x 2-cm burns were created on each animal with milled aluminum templates (100 degrees C) with varying contact times. Conversion of burn depth in these wounds was documented by serial laser Doppler imager scanning over a 5-hour period. Animals received Ringer's lactate resuscitation at 0, 2, 4, 6, and 8 ml/kg/%burn. Serial laser Doppler scanning directly demonstrated progressive loss of perfusion to partial-thickness burns dependent upon the amount of fluid resuscitation. Conversion of partial- to full-thickness burns in this rat model (documented by laser Doppler microvascular assessment) was dependent upon how the animals were resuscitated.

Burn resuscitation with two doses of 4 mL/kg hypertonic saline dextran provides sustained fluid sparing: a 48-hour prospective study in conscious sheep

BACKGROUND

The large fluid volumes usually required for burn resuscitation can be suppressed for 8 to 12 hours by intravenous infusion of 4 mL x kg(-1) hypertonic saline dextran (HSD) 1 hour after burn. We hypothesized that a double (8 mL x kg(-1)) dose of HSD or two repeated doses of 4 mL x kg(-1) could enhance or prolong the volume sparing.

METHODS

We produced a full-thickness flame burn covering 40% of the body surface on 18 anesthetized sheep. One hour after the burn, the animals were awake and resuscitated with either (1) lactated Ringer's solution (LR) only, (2) 8 mL x kg(-1) HSD followed by LR, or (3) 4 mL x kg(-1) HSD followed by LR, with a second dose of 4 mL x kg(-1) HSD administered when net fluid accumulation increased to 20 mL x kg(-1). For all regimens, infusion rates were adjusted to produce a urine output of 1 to 2 mL x kg(-1) x h(-1).

RESULTS

Animals resuscitated with only LR required fluid volumes identical to that predicted by the Parkland formula for the first 12 hours. Infusion of 8 mL x kg(-1) HSD initially created a net fluid loss (urine output > infused volume), followed by a rebound fluid requirement eventually equaling that of animals treated with LR only. Animals treated with two separate doses of 4 mL x kg(-1) HSD generally did not experience a net fluid loss or a rebound fluid requirement. Also in the HSD x 2 group, peak and net fluid accumulation was less than that of the other two groups from 18 hours through 48 hours, although the difference was not significant.

CONCLUSION

An initial 4 mL x kg(-1) dose of HSD reduces fluid requirements early after burn, and a second dose administered after an appropriate interval may prolong volume sparing through 48 hours. An 8 mL x kg(-1) continuously infused initial dose was without prolonged fluid sparing effect. The volume-sparing effect of HSD is thus dependent on all of the following: dose, dosing interval, and infusion rate.

Application of base deficit in resuscitation of trauma patients

Clinical measures, such as blood pressure or urine output, have been the traditional methods used to assess tissue perfusion in trauma patients with hypovolemia. Hypoperfusion of tissues results in increased levels of lactate and carbonic acids. Base deficit is a clinical measure of metabolic acidosis that normalizes rapidly with adequate resuscitation and hemorrhage control, and it can be used to monitor the initial care of a patient with trauma. The method used to measure base deficit is discussed, along with its clinical uses and limitations. A case study is used to correlate changes in base deficit with other clinical parameters.