Continuing Education Activity

In the United States, approximately 500,000 people seek care for burn injuries yearly. For civilians, these injuries are typically sustained in house fires, motor vehicle crashes, and work-related accidents. In combat, burn injuries represent 5% to 10% of combat casualties. The severity of burns is determined by the intensity of the thermal energy sustained, duration of exposure, and the area of the body affected. These parameters determine whether a patient will require treatment at a dedicated burn center. This activity emphasizes the importance of burn fluid resuscitation and highlights the role of the interprofessional team in managing burn patients.

Objectives:

• Identify the formula used to estimate fluid resuscitation in burn patients.
• Describe the types of fluids used to resuscitate and maintain patients with burns.
• Review the complications of burn fluid management.
• Outline the importance of improving care coordination among the interprofessional team to enhance fluid resuscitation in burn patients.

Introduction

In the United States, approximately 500,000 people seek care for burn injuries yearly. For civilians, these injuries are typically sustained in house fires, motor vehicle crashes, and work-related accidents. Burn injuries represent 5% to 10% of combat casualties in combat.[1]

The World Health Organization (WHO) and the Center for Disease Prevention and Control (CDC) report burns as one of the most common causes of home injuries and children under 19.[2] Several practice guidelines have been released regarding the significance of the optimal care and management to be provided for burn injuries. However, from 2014, specific updates have been added to cover the demands in resource-limited regions and the resource-abundant territories.[3] Not to emphasize that mentioned practice guidelines would discuss the preferred decisions based on costs, benefits, potential, harms, values, and preferences, rather than only established scientific recommendations.[4] However, the resource-limited settings would explicitly target to provide the most practical and cost-effective recommendations in the limited access settings to the standard personnel, training, supplies, and equipment.[5] Specific zones of poverty in upper-middle- and high-income countries and mass casualty, along with most cases in low and middle-income countries, would benefit from these practice guidelines.

The severity of burns is determined by the intensity of the thermal energy sustained, duration of exposure, and the area of the body affected. These parameters determine whether a patient will require treatment at a dedicated burn center.

Many burn injuries are sustained in motor vehicle crashes, which can often become multi-trauma events. It is imperative that the initial provider not become so engrossed in the apparent injury that they do not consider more life-threatening injuries that might be less overtly evident. Airway assessment, control of hemorrhage, and the advanced trauma life support guidelines must be followed.[6] Additionally, the American Burn Association (ABA) guidelines mirror the ATLS.[7]

Adequacy of resuscitation should be confirmed. This confirmation renders an invaluable part of patient management and should be considered in a timely schedule. Various monitoring methods for the adequacy of fluid resuscitation have been introduced. Accordingly, urine output monitoring with an indwelling catheter, including a Foley catheter, is considered the most common measure for this purpose and even more important than strict adherence to Parkland or any other fluid resuscitation formula. However, other clinical signs, including but not limited to the faint distal pulses in a newly burnt patient, implies inadequate fluid resuscitation and later peripheral edema due to a large amount of replaced fluid. Maintenance of an hourly urine output at 0.5 mL/kg/hr in adults is recommended. Oliguriec, and anuric patients with severe burns, despite appropriate fluid resuscitation, generally do not survive.[8]

Anatomy and Physiology

Arguably the greatest issue surrounding patients sustaining burn injuries is fluid loss. Therefore, volume replacement is crucial. Burns management can be divided into three phases: early resuscitative, wound management, and rehabilitative/reconstructive. This article will primarily discuss the early resuscitative phase after initial stabilization has been performed. Although guidelines have been present since the early 1960s, fluid management protocols remain controversial for patients in the first 24 hours.

In the early resuscitative phase, the major concern is hypovolemia due to capillary permeability. Thermal injury prompts the release of inflammatory markers not only at the site of injury but also systemically. These inflammatory markers increase the capillary permeability throughout the body and cause a massive fluid shift out of the intravascular compartment. The inflammatory response from thermal burns far surpasses that of trauma and sepsis patients.[9] 

Among these inflammatory markers, histamine is likely responsible for the early phase of burn injury, creating capillary permeability.[10] Cardiac output is decreased, and systemic vascular resistance is increased, worsening the state of shock. Burn shock is a combination of distributive, cardiogenic, and hypovolemic shock.[11] Therefore, it is imperative to replace the fluid in the intravascular compartment to preserve tissue perfusion of vital organs.

Initial burn shock during the first 24 to 48 hours following major burns might be identified with myocardial depression, increased capillary permeability, large fluid shifts, and depleted intravascular volume.[2][12]

Indications

Like any trauma patient, fluid management based on weight and burn size should immediately occur after the primary airway evaluation. However, fluid bolus administration in patients with burns without any evidence of hypovolemia is unnecessary and has several consequences, including further exacerbation of edema formation, and therefore should be avoided.[11] An intact gastrointestinal tract should be considered as a conduit for fluid resuscitation. However, it should be noted that a significant number of burn patients with a remarkable involved total body surface area with burn would not tolerate oral resuscitation. Accordingly, oral fluid resuscitation is an acceptable recommendation in patients with less than 30% of involved total body surface area.[13] 

Burns with greater than 15% body surface area (BSA) in adults and 10% BSA in children require formal fluid resuscitation, calculated with the Lund and Browder chart for children and the Wallace rule of 9s for adults.[14] The Rule of Nines estimation of body surface area burned is based on assigning percentages to different body areas. The entire head is estimated as 9% (4.5% for anterior and posterior). The entire trunk is estimated at 36% and can be further broken down into 18% for anterior components and 18% for the back. The anterior aspect of the trunk can further be divided into the chest (9%) and abdomen (9%). The upper extremities total 18% and thus 9% for each upper extremity. Each upper extremity can be divided into anterior (4.5%) and posterior (4.5%). The lower extremities are estimated at 36%, 18% for each lower extremity. Again this can be further divided into 9% for the anterior and 9% for the posterior aspect. The groin is estimated at 1%.[15]

Goals for fluid resuscitation are generally accepted as urine output greater than 0.5ml/kg per hour, base deficit less than 2, systolic blood pressure greater than 90 mm Hg, and clinically with peripheral pulses palpable and no altered mental status. Although studies have shown these variables to be adequate predictors of fluid resuscitation, many physicians rely solely on urine output (UOP). In 1991, Dries and Waxman found that vital signs and urine output did not appreciably change after volume repletion, whereas measurements from pulmonary artery catheterization (PAC) were quite significant.[16] This suggested cardiac output was the most sensitive measure to guide fluid therapy. However, doing so requires placement of the pulmonary artery catheter, and as such, many burn units are reluctant to use this method for guidance. Other proposed methods for goal-directed therapy include transpulmonary thermodilution and arterial pressure wave analysis, but these have not been extensively studied.

An exception to the previously stated UOP goal occurs in patients with rhabdomyolysis and/or acute renal failure, with mortality as high as 70% in severe burns. These patients require fluids at a rate that produces a UOP of 1 ml/kg hour.[17] However, it should be noted that "more is not better," and the risk of fluid creep can be as life-threatening as the burn injury itself. Neither mannitol nor sodium bicarbonate is more effective in acute renal failure than fluid loading alone.[18][19]

According to the American Burn Association's practice guidelines, patients with greater than 15 percent total body surface area (TBSA) nonsuperficial burns should receive intravenous fluid resuscitation. Moreover, placement of two large-bore intravenous (IV) lines in unburned skin and, if possible, central venous access are indicated. However, the decision for the placement of the latter should be individualized. Also, IV lines can be placed even through burned skin if other alternatives are not possible to avoid delays in resuscitation.[20]

The resuscitation of patients with burn trauma and the role of albumin solutions in the process remains equivocal. Despite the physiologic rationale to support the role of albumin administration in acute burn trauma, the significantly high mortality rate in the group of patients treated with albumin was against the albumin replacement.[21][22]

Preparation

Multiple resuscitation formulas are utilized for burn resuscitation. However, the Parkland and modified Brooke formulas have been most commonly utilized, among others. Accordingly, the recommendations for lactated Ringer’s solution with all these formulas range from 2 to 4 mL/kg/day % burn.[23]

One of the most important concerns about pediatric patient resuscitation is the fundamental differences in body surface area and skin thickness.[24] Children have a greater ratio of body surface area to the body mass, making them more susceptible to hypothermia and increasing fluid requirements for any size burn. Moreover, the body surface area is distributed differently in children. Children have larger heads that can approach even up to 18% of total body surface area [TBSA]) and smaller legs.[25] 

Another important difference in fluid resuscitation management in the pediatric population is the threshold for initiating fluid replacement. While fluid resuscitation is recommended for burns greater than or equal to 15% of (TBSA) in children, it might be started in adult patients with equal to or greater than 20 % of TBSA.[26]

Technique

The original Parkland formula incorporates both crystalloids and colloids. Crystalloids have a more negligible volume expansion effect than colloids because of the increased capillary permeability during early burn injury. However, colloids will pass into the extravascular space, creating a shift in oncotic pressure that expands into the third space.[27] 

A study by Perel et al. concluded that randomized controlled trials provide no evidence that resuscitation with colloids reduces the risk of death compared with crystalloids in burn resuscitation. Given that there is no associated improvement in survival and colloids are more expensive, they are used less in clinical practice. At this time, crystalloids are the consensus of fluids for burn management.[28]

The Parkland formula (also called the Baxter formula), developed in 1968 by Dr. Charles Baxter, is perhaps the most widely recognized fluid replacement formula for burn injuries. It stipulates that 2 to 4 ml of Ringer's Lactate per kilogram of weight per percentage of body surface area burned, with the first half given over the first 8 hours and the remainder given over the next 16 hours. Parkland formula implies 4 mL/kg/%TBSA (3 mL/kg/%TBSA in children) = total amount of crystalloid fluid during the first 24 hours.[29] Discrepancies still exist in patients where the body surface area calculation is unreliable, for example, pediatrics and patients who suffer from obesity. The Parkland formula was unique at its time of conception in that it recommended higher volumes of fluid than its predecessors. 

Burn injuries are a leading cause of unintentional death in children, although most of these are considered minor. Due to their small circulating blood volumes, prompt resuscitation for pediatric burn victims is paramount. Adult resuscitation guidelines must be altered for children because the distribution of their body surface area differs significantly. The Lund and Browder chart considers these differences by providing a pediatric-specific calculation.

According to some recent surveys to evaluate the emergency department healthcare professionals' knowledge considering the initial interventions for pediatric burn patients, almost 75 % declared the Parkland formula used in acute management.[30] However, the body surface area-based Galveston and BSA-incorporated Cincinnati formulas have also been adopted into pediatric practice.[31]

The Evans formula was developed in 1952 and was the first burn formula created to account for body weight and burn surface area. The first 24 hours entails 1 ml/kg/% BSA of crystalloids plus 1 ml/kg/% BSA colloids plus 2000 ml glucose in water. In the next 24 hours, crystalloids at 0.5 ml/kg/% BSA, colloids at 0.5 ml/kg/% BSA, and the same amount of glucose in water as in the first 24 hours.      

The Brooke formula, initially described in 1953, uses 1.5 ml/kg/% BSA of lactated Ringer's solution plus 0.5 ml/kg/% BSA of colloid and 2 L of 5% dextrose in water. This formula was later modified to 2 ml/kg/% BSA of lactated Ringer's solution with colloid not given in the first 24 hours postburn.[32][33]

Ringer's lactate is recommended for initial resuscitation in all age groups, but infant patients will also require dextrose due to their limited glycogen stores. Because of this, pediatric burn resuscitation formulas are always 2-figure calculations: the estimated fluid resuscitation (EFR) and added maintenance fluids (MF) with or without dextrose, depending on the child's age. The cutoff for using the adult formula is generally agreed to be between 30 to 50 kg.[31]

Currently, the two major pediatric formulas are the Cincinnati formula and the Galveston formula. To date, there has not been a clinical comparison study between these.[34][35]

Urine output is regarded as the resuscitation goal in pediatric burn management. For children under 30 kg, 1 ml/kg per hour is recommended; for children over 30 kg, 0.5 ml/kg per hour is the goal. As with adults, using UOP as the sole measure of efficacy is controversial and often misleading. Sheridan et al. have suggested that in infants, the goals be determined by sensorium, physical exam, pulse, and systolic blood pressure in addition to UOP.[36][37] The same additional parameters for therapy endpoints exist in the pediatric population: lactate, invasive transpulmonary thermodilution, and central venous pressures. These represent areas in need of further investigation for both children and adults.

Complications

Patients often arrive at burn centers having received overzealous hydration en route. First responders and inexperienced physicians often overestimate burn size and run the intravenous fluids wide open, with patients getting their first 8-hour Parkland requirements in only 1 to 2 hours.[38] 

Alternatively, the phenomenon referred to as “fluid creep” presents a challenge to burn patients regarding over-resuscitation. Giving too much volume can be detrimental, potentially creating pulmonary and cerebral edema or compartment syndrome of the extremities or abdomen. Several parameters contribute to fluid overloading, which has become a global issue. These parameters include the modified Parkland formula that has excluded colloid use, the impact of goal-directed resuscitation, and the overzealous, on-the-scene crystalloid resuscitation, combined with subsequent inefficient titration of fluid administration and lack of timely reduction of infusion rates.[9] Several factors have been identified that predispose burn patients to increased fluid requirements, including inhalation injury, delay in resuscitation, polytrauma, or high-voltage electrical injury.[39]

For this reason, infusion rates should be re-calculated hourly, and rates should not be increased by more than 20% to 25%.

Physicians and nurses seem to have mastered the concept of increasing fluid rates when urine output (UOP) is less than 30 ml per hour but are less likely to decrease the infusion rate when UOP rises above the suggested maximum of 1 ml/kg per hour. One study demonstrated that infusion rates were only appropriately decreased 35% of the time.[40] Additionally, it has been suggested that using UOP as the sole indicator of adequate resuscitation is less accurate than other parameters such as base deficit and lactic acid. Differing opinions and conflicting evidence contribute to large inter-physician variability in the treatment of burn patients.

Circumferential burns of the extremities can undergo a tourniquet effect due to the forming eschar, and these patients will need urgent escharotomy before fluid resuscitation. However, these events are rare except in cases of electrical burns, burns with underlying fracture, and burns with vascular injury.[41]

Clinical Significance

After many years of researching burn patient pathophysiology and outcomes, it is evident that prompt fluid resuscitation is essential for survival in these patients.[42] Since efficient fluid replacement protocols have been enacted, fewer patients die in the first 48 hours.[43] Suboptimal resuscitation has been shown to increase burn depth and create a longer period of shock, which increases mortality.[44]

Enhancing Healthcare Team Outcomes

The discussed practice guidelines for fluid management in burn patients were designed for a primary audience of health care professionals responsible for providing acute care fluid management for burn patients. Although the recommendations have been crafted to include protocols germane to resource-limited sites, the material should also be pertinent in high-resource settings. Policy-makers, public health experts, and hospital managers can also use these outlines. Optimal management of burn patients requires mandatory, explicit communication between emergency medical service (EMS), nursing staff, and physicians. Balancing fluid resuscitation in these patients is the most essential and critical aspect of their care. There exists a finite window of appropriate resuscitation in which too much or too little fluid can have catastrophic consequences.[45]

Communication is a multi-dimensional, multi-factorial tool that is critical to all aspects of health care. Generally, an intensivist and/or plastic surgeon leads burn victim cases. However, in addition to nursing and ancillary staff, other specialists will be involved in the patient's care. A cross-sectional, descriptive, analytic study identified communication barriers for these patients, including the hectic environment of the intensive care unit (ICU) and poor communication of symptoms by the patient due to a medical condition.[46] Therefore, providing a safe and calm environment for patients to communicate their needs is imperative to achieving clear communication.

For burn victims, an interprofessional approach must be incorporated to obtain the best outcomes. The nursing staff needs to work with the clinical team (MDs, DOs, NPs, and PAs) to monitor fluids, urine output, vital signs, and breath sounds to avoid fluid overload while maintaining appropriate hydration. Any patient status changes require immediate documentation and communication to the appropriate interprofessional team member(s), so any necessary interventions can be initiated. Burn victims are challenging; untoward changes may be caused by sepsis, cardiac deficiency, neurogenic causes, or lack of fluid balance. An astute team of experienced nurses and clinicians is needed for the best clinical success. [Level 5]

This research was supported (in whole or part) by HCA Healthcare and/or an HCA Healthcare affiliated entity. The views expressed in this publication represent those of the author(s) and do not necessarily represent the official views of HCA Healthcare or any of its affiliated entities.