Trends in blood conservation in burn care

Determinants and time to blood transfusion among thermal burn patients admitted to Mulago Hospital

Background

Blood transfusion, a practice under re-evaluation in general, remains common among thermal burn patients due to the hematological alterations associated with burns that manifest as anemia. Today advocacy is for restrictive blood transfusion taking into account individual patient characteristics. We went out to identify the parameters that may determine transfusion requirement and the time to blood transfusion for thermal burn patients in Mulago Hospital in order to build statistics and a basis to standardize future practice and Hospital protocol.

Methods

112 patients with thermal burns were enrolled into a prospective cohort study conducted in the Surgical Unit of the Accidents and Emergency Department and Burns Unit of Mulago Hospital. Relevant data on pre-injury, injury and post-injury factors was collected including relevant laboratory investigations and treatment modalities like surgical intervention. Patients were clinically followed up for a maximum period of 28 days and we identified those that were transfused.

Results

22.3% of patients were transfused. The median time to transfusion was 17 days from time of injury and varied with different patient characteristics. The median pre-transfusion hemoglobin (Hb) level was 8.2 g/dL. Transfusion was significantly related to; admission to the intensive care unit (p = 0.001), a body mass index (BMI) <2 kg/m² (p = 0.021), % total burn surface area (TBSA) >20 (p = 0.049), pre-existing illness (p = 0.046), and white blood cell (WBC) count <4000 or >12,000/μL (p = 0.05).

Conclusion

Pre-existing illnesses, a low BMI, TBSA of >20%, admission to the intensive care unit and abnormalities in the WBC count are useful predictors of blood transfusion among thermal burns patients admitted to Mulago Hospital. The precise time to transfusion from time of burns injury cannot be generalized. With close monitoring of each individual patient lies the appropriateness and timeliness of their management.

Important Developments in Burn Care

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Explain the epidemiology of severe burn injury in the context of socioeconomic status, gender, age, and burn cause. 2. Describe challenges with burn depth evaluation and novel methods of adjunctive assessment. 3. Summarize the survival and functional outcomes of severe burn injury. 4. State strategies of fluid resuscitation, endpoints to guide fluid titration, and sequelae of overresuscitation. 5. Recognize preventative measures of sepsis. 6. Explain intraoperative strategies to improve patient outcomes, including hemostasis, restrictive transfusion, temperature regulation, skin substitutes, and Meek skin grafting. 7. Translate updates in the pathophysiology of hypertrophic scarring into novel methods of clinical management. 8. Discuss the potential role of free tissue transfer in primary and secondary burn reconstruction.

SUMMARY

Management of burn-injured patients is a challenging and unique field for plastic surgeons. Significant advances over the past decade have occurred in resuscitation, burn wound management, sepsis, and reconstruction that have improved outcomes and quality of life after thermal injury. However, as patients with larger burns are resuscitated, an increased risk of nosocomial infections, sepsis, compartment syndromes, and venous thromboembolic phenomena have required adjustments in care to maintain quality of life after injury. This article outlines a number of recent developments in burn care that illustrate the evolution of the field to assist plastic surgeons involved in burn care.

Surgical burn wound infections and their clinical implications

Typically, burn wound infections are classified by the organisms present in the wound within the first several days after injury or later by routine surveillance cultures. With universal acceptance of early excision and grafting, classification of burn wound colonization in unexcised burn wounds is less relevant, shifting clinical significance to open burn-related surgical wound infections (SWIs). To better characterize SWIs and their clinical relevance, the authors identified the pathogens responsible for SWIs, their impact on rates of regrafting, and the relationship between SWI and nosocomial infection (NI) pathogens. Epidemiologic and clinical data for 71 adult patients with ≥ 20% TBSA burn were collected. After excision and grafting, if a grafted site had clinical characteristics of infection, a wound culture swab was obtained and the organism identified. Surveillance cultures were not obtained. SWI pathogen, anatomic location, postburn day of occurrence, and need for regrafting were compiled. A positive culture obtained from an isolated anatomic location at any time point after excision and grafting of that location was considered a distinct infection. Pathogens responsible for NIs (urinary tract infections, pneumonia, bloodstream and catheter-related bloodstream infections, pseudomembranous colitis, and donor site infections) and their postburn day were identified. The profiles of SWI pathogens and NI pathogens were then compared. Of the 71 patients included, 2 withdrew, 6 had no excision or grafting performed, and 1 had incomplete data. Of the remaining 62 patients, 24 (39%) developed an SWI. In these 24 patients, 70 distinct infections were identified, of which 46% required regrafting. Candida species (24%), Pseudomonas aeruginosa (22%), Serratia marcescens (11%), and Staphylococcus aureus (11%) comprised the majority of pathogens. Development of an SWI with the need for regrafting increased overall length of stay, area of autograft, number of operative events, and was closely associated with the number of NIs. The %TBSA burn and depth of the burn were the main risk factors for SWI with need for regrafting. The SWI pathogen was identified as an NI pathogen 56% of the time, with no temporal correlation between shared SWI and NI pathogens. SWIs are commonly found in severely burned patients and are associated with regrafting. As a result, patients with SWIs are subjected to increased operative events, autograft placement, and increased length of hospitalization. In addition, the presence of an SWI may be a risk factor for development of NIs.

Red blood cell transfusion following burn

A severe burn will significantly alter haematologic parameters, and manifest as anaemia, which is commonly found in patients with greater than 10% total body surface area (TBSA) involvement. Maintaining haemoglobin and haematocrit levels with blood transfusion has been the gold standard for the treatment of anaemia for many years. While there is no consensus on when to transfuse, an increasing number of authors have expressed that less blood products should be transfused. Current transfusion protocols use a specific level of haemoglobin or haematocrit, which dictates when to transfuse packed red blood cells (PRBCs). This level is known as the trigger. There is no one 'common trigger' as values range from 6 g dl(-1) to 8 g dl(-1) of haemoglobin. The aim of this study was to analyse the current status of red blood cell (RBC) transfusions in the treatment of burn patients, and address new information regarding burn and blood transfusion management. Analysis of existing transfusion literature confirms that individual burn centres transfuse at a lower trigger than in previous years. The quest for a universal transfusion trigger should be abandoned. All RBC transfusions should be tailored to the patient's blood volume status, acuity of blood loss and ongoing perfusion requirements. We also focus on the prevention of unnecessary transfusion as well as techniques to minimise blood loss, optimise red cell production and determine when transfusion is appropriate.

Hemostasis in burn surgery--a review

Over the past 30 years, techniques of early excision and grafting along with enhancement of critical care have significantly improved survival following burn injury. Despite these advancements, large volume blood loss associated with surgical intervention continues to be a challenging aspect of burn surgery. This review article will examine the methods of limiting blood loss during surgical procedures.

Burn injuries

PURPOSE OF REVIEW

To summarize new advances and research findings that relate to the treatment of burn victims.

RECENT FINDINGS

Recent advances in burn resuscitation and critical care reflect a better understanding of the acute phase pathophysiology of severe burns. Aggressive management of the unstable burn airway is always the most important clinical priority. Emphasis has been placed on the early identification of inhalation injury and its impact on fluid resuscitation, as well as on a protective lung strategy to reduce the development of pulmonary edema, acute lung injury and pneumonia, and to reduce the risk of barotrauma. New blood markers, such as serum cholinesterase and inflammatory cytokines, have been introduced to assist in the prognosis of morbidity and mortality, beyond the traditional vital signs. At this time, however, these are available only for research purposes. Finally, early burn wound excision and coverage with new biodegradable materials results in less pain and more rapid healing for the patient.

SUMMARY

The combination of innovative approaches and a dedicated burn team is expected to continue to improve survival in the next few years even in the most severe cases.

Safe and successful restriction of transfusion in burn patients

An acceptable strategy for transfusion of burn patients has not been specifically identified. In 1999, we empirically adopted a hemoglobin (Hb) transfusion trigger of 7.0 g/dl or greater in our burn center. The purpose of this study was to evaluate the effects of this restrictive transfusion strategy. Retrospective comparison of adults with 20% or greater TBSA treated from 1999 to 2004 (restrictive group; REST) with patients treated before our adoption of the restrictive transfusion strategy (1997-1998: liberal group; LIB). The REST group (n = 135, age 42 +/- 17 years, %TBSA burn 37 +/- 14, and 26% incidence of inhalation injury) did not differ significantly from the LIB group (n = 37, age 42 +/- 16 years, %TBSA burn 38 +/- 17, and 35% inhalation injury). The Hb triggering a transfusion was 7.1 +/- 1.2 g/dl in the REST group, compared with 9.2 +/- 2.1 g/dl in the LIB group (P < .001). The REST group received significantly fewer units of blood per day than the LIB Group. Patients in the REST group appeared to have significantly better organ function, and there were no differences between the groups in the incidence of acute myocardial infarction. Mortality at 30 days was significantly lower in the REST group (19% vs 38%; P = .03), as was overall in-hospital mortality (22% vs 46%; P = .003). Transfusion restriction appears to be safe and resulted in fewer transfusions among this group of burn patients. Prospective studies are needed before broadly recommending a transfusion trigger of 7.0 g/dl.

Acute cholecystitis in burn patients

Acute cholecystitis is a complication in critical illnesses, including burns. The purpose of this report is to review one institution's experience with this complication during a 21-year time period. A computerized burn registry was used for data collection and analysis in this retrospective review. Twenty patients developed cholecystitis from a total burn admission population of 10,762 in this 21-year period (0.18%). Mean patient age was 43.5 years, and their mean burn size was 37.4% with a mean full-thickness burn size of 23% TBSA. Mean patient length of stay was 77.4 days. Sixteen of these patients were intubated and mechanically ventilated for a mean of 56 days. Total parental nutrition was required in 12 patients. The use of total parental nutrition steadily decreased over the length of the study, and early enteral tube feed use has become the norm. All but two patients were in the Burn Intensive Care Unit at the time of diagnosis. Men outnumbered women by three to one. Nine patients with positive sonograms were successfully managed without surgical intervention. Two of these patients also had positive hydroxy iminodiacetic acid scans. Surgically managed patients were treated with both open and laparoscopic cholecystectomy as well as cholecystostomy tube placement. Mortality was 25%. Acute cholecystitis remains a serious although relatively rare complication in burn patients. Patients often have an unreliable physical examination, several possible causes of fever, and abnormal laboratory results. A high index of suspicion and sound clinical judgment is required to manage this rare-but-challenging problem.

Transfusion-free pediatric burn surgery: techniques and strategies

More than 1.3 million children sustain burns each year, resulting in 40,000 admissions and more than 3000 pediatric deaths. Pediatric burn surgery has been described as excessively bloody. Strategies to reduce intraoperative blood loss include the use of topical thrombin and epinephrine, extremity tourniquets, acute normovolemic hemodilution, and hypotensive anesthesia. This study reviews the single surgeon pediatric burn experience at a children's hospital and describes a comprehensive blood conservation protocol to achieve transfusion-free pediatric burn surgery. A retrospective chart review of consecutive pediatric burn surgeries from July 2000 to April 2002 was performed. Patient demographics, burn characteristics, treatment, blood loss, laboratory values, transfusion history, and complications were reviewed. Blood loss per percent total body surface area (TBSA) treated as well as percent total blood volume (TBV) loss divided by percent TBSA treated were calculated. A total 31 burn surgeries in 23 patients were reviewed. The average age was 7 years (range, 9 months-17 years). There were 17 extremity, 6 trunk, and 2 head/neck burns. The average TBSA burned was 15% (range, 1-55%). The protocol to reduce intraoperative blood loss consisted of the debridement of full-thickness burns with electrocautery and partial-thickness burns with dermabrasion. All debrided or harvested surgical sites were treated immediately with epinephrine solution-soaked pads. All graft harvest sites were injected with an epinephrine solution before harvesting split-thickness skin grafts. The average TBSA treated per surgery was 7% (range, 1-29%). The average blood loss per percent TBSA treated was 15 mL (range, 0.7-37 mL). The average percent TBV/percent TBSA was 0.76% (range, 0.04-3.6%). All 20 patients underwent surgical debridement, 7 patients were treated with AlloDerm and ultrathin split-thickness skin grafts, 2 with full-thickness skin grafts, and 17 with split-thickness skin grafts alone. Five children required blood transfusions. These burns averaged 32% TBSA (range, 20-55%). All 5 children receiving transfusions had anemia of thermal injury and demonstrated an average preoperative drop in hematocrit of 12% (range, 10-14%). There was a 29% complication rate, with 7 patients experiencing partial graft loss, and 1 patient who developed a postgraft contracture that required revisional surgery. There was a single mortality secondary to systemic inflammatory response syndrome and acute respiratory distress syndrome. After the proposed pediatric burn treatment protocol, intraoperative blood loss requiring transfusion can be minimized or eliminated. Large TBSA burns must be surveilled for burn wound anemia that may ultimately require blood transfusion.

Establishing transfusion needs in burn patients

BACKGROUND

Despite blood-conservation techniques, hemorrhage during burn excision remains substantial. It is difficult to predict the blood loss that will occur per operation and how many units the patient will require during surgery. This may result in high cross-match-to-transfusion ratios (CMTRs).

METHODS

A retrospective chart review from 2001 to 2003 was performed. All adult patients with >20% total body surface area burns who underwent surgery were included in the study. Variables examined were centimeters excised, estimated blood loss, packed red blood cells transfused during surgery, preoperative and postoperative hematocrit, and CMTR.

RESULTS

There were 273 operations. The average estimated blood loss was 820 mL, and; the median posttransfusion hematocrit was 27. Based on the area excised and units transfused, a ratio of packed red blood cells/cm excised was determined. A total of 1.78 U blood were transfused/1000 cm(2) excised to keep hematocrit between 25 and 31; P = 0.02.

CONCLUSIONS

Estimation of excision area can predict transfusion need, which at our institution yields a low CMTR.

Damage limitation in burn surgery

Burn injury differs from other types of trauma in the apparent lack of urgency for treatment. We argue that in order to limit physiological damage and the development of multi-organ failure, management of the burn wound must be immediate and aggressive. Supportive fluid treatment should be judicious in order to prevent excessive oedema causing wound extension. Some potential strategies utilising oral fluid resuscitation are discussed, and potential pharmacological interventions. When associated with other trauma, major burn injury has a detrimental effect on morbidity and mortality, and surgical management of both aspects of a patient's injuries are altered.

Blood transfusion in burns: what do we do?

Over 11 million units of blood are transfused yearly in the United States. Although blood transfusion is common in burns, data are lacking on appropriate transfusion thresholds. The purpose of the study was to identify current burn center physician blood transfusion practices. A 30-question survey of blood transfusion practices was developed and sent to burn center directors. The survey assessed demographics, burn experience, and blood transfusion thresholds. Physicians were asked to list factors affecting their blood transfusion thresholds and then to give their blood transfusion threshold for patients based on age and percent burn. The final section presents three case scenarios with alterations in one physiological parameter to assess the effect on transfusion thresholds. A total of 55 of the 180 surveys (31%) were returned. Mean number of burn beds was 15.7 +/- 1.4, with 264 +/- 25 burn admissions per year. The respondents had been in burn care for 15.9 +/- 1.4 years. Their mean hemoglobin transfusion threshold was 8.12 +/- 1.7 g/dl. The most frequent reasons for transfusion were ongoing blood loss (22%), anemia (20%), hypoxia (13%), and cardiac disease (12%). Inhalation injury influenced the decision to transfuse blood in 34%. The hemoglobin level below which respondents would transfuse blood increased with increasing TBSA burn, history of cardiac disease, acute respiratory distress syndrome, and age. Blood transfusion thresholds in burns vary based on burn percentage, age, and presence of cardiac disease. To date, no standard of care exists for blood transfusions in burns. Future prospective studies are needed to determine the appropriate use of blood in burns.