Overview of Burn Fluid Management
In the US, about half a million people seek treatment for burns every year. The majority of burns in the general population are from house fires, car crashes, and accidents at work. Burns also account for 5% to 10% of injuries in combat situations.
The World Health Organization (WHO) and the Center for Disease Control and Prevention (CDC) have found that burns are one of the top causes of household injuries, especially in kids under 19. There are guidelines in place to ensure the best care and treatment for burn injuries. These guidelines have been updated since 2014 to include strategies for areas with limited resources as well as areas where resources are plentiful. These guidelines consider the balance of costs and benefits, possible harm, beliefs and preferences, rather than just scientific recommendations. Guidelines for resource-limited places aim to provide useful and affordable suggestions in situations of limited staff, training, supplies, and equipment.
These guidelines are particularly helpful for economically disadvantaged areas in wealthier countries, places with large numbers of injuries, as well as most situations in lower-income countries.
The seriousness of a burn depends on the heat level, how long the person was exposed, and the area of the body affected. These factors will decide if a patient should be treated at a specialized burn center.
A lot of burn injuries come from car crashes, which often lead to multiple injuries at once. It’s crucial for healthcare providers to not just focus on the obvious injury, but also to consider other potentially more severe injuries that might not be as visible. Procedure, like examining the airways, controlling bleeding, and following advanced life support guidelines, have to be carried out.
Lastly, it’s essential to confirm that treatment is having the desired effect. This is a key part of patient care and should be done in a well-timed manner. Usually, this is done by checking the patient’s urine output with a catheter, which can provide a reliable measure of whether the patient’s fluids are being restored properly. However, other clinical signs like faint pulses in a patient with a recent burn can suggest that their fluids are not being restored properly and they are likely to have swelling due to too much replacement fluid. For adults, aiming for a urine output of 0.5 mL/kg/hr is standard. Patients with severe burns who have low or no urine output, despite proper fluid replacement, usually don’t survive.
Anatomy and Physiology of Burn Fluid Management
The main challenge when someone has burn injuries is the loss of body fluids. Replacing these fluids is critically important. Burn care can be split into three stages – the initial phase where fluids are replaced, the stage where the burn wound is managed, and the final phase of rehabilitation or reconstruction. This piece will mainly focus on the first phase, which occurs after the person has been stabilized. Guidelines for how to manage body fluids in burn patients in the first 24 hours have been available since the 1960s, but there’s still a lot of debate about the best approach to this.
In the initial resuscitative phase, the most important concern is low volume of blood plasma due to leakage from the blood vessels. When a burn occurs, the body releases inflammation markers that affect the whole body, not just the burnt area. These markers make the blood vessels leaky and cause a large amount of body fluid to leak from blood vessels. The inflammation response from burns is more significant than what we see in trauma or severe infection patients.
One of these inflammation markers is histamine, which probably plays a key role in the early phase of burn injury by making the blood vessels leaky. This results in less blood being pumped by the heart and increased resistance in blood vessels, both of which make the shock due to burn worse. Shock due to burn is made up of a few different kinds of shock. Therefore, it’s absolutely essential to replace the body fluids in the blood vessels to maintain the blood supply to vital organs.
In the first 24 to 48 hours following major burns, the person might go into initial burn shock which could involve weakening of the heart muscle, increased leakiness of blood vessels, large shifts in body fluids, and reduction in fluid volume in blood vessels.
Why do People Need Burn Fluid Management
If someone has been injured, they will need fluids right away, based on their weight and the size of the injury. This is especially true if they are having trouble with their airway, the passage that air uses to go in and out of the lungs. However, giving fluids all at once to a burn patient who isn’t showing signs of having too little fluid inside their body is unnecessary. In fact, it could even make the swelling worse. If possible, fluids should be given through the gastrointestinal tract – this essentially means drinking them.
However, patients with large burns (covering a significant portion of their body) might not be able to drink enough fluids. In this case, it’s generally okay for patients with burns covering less than 30% of their body to drink fluids.
Patients with burns bigger than 15% of their body (for adults) or 10% (for children) require a precise calculation of fluids needed by doctors. This is done using different charts for children and adults, like the Lund and Browder chart and the Rule of Nines. The Rule of Nines estimates the burned body surface area by giving percentages to different body parts. For example, the head counts for 9%, the trunk counts for 36%, and so on.
The goals for giving fluids are decided based on factors like the patient’s urine output, acid levels in the body, blood pressure, and presence of a clear state of mind. A reliable indicator for water balance in the body typically used by doctors is the amount of urine the patient produces. However, other methods have been proposed, such as measuring blood flow in the pulmonary artery – a large blood vessel connected to the heart – but these techniques are not widely tested yet.
Patients with muscle damage or kidney failure require a different approach. These conditions can have a high risk of death in severe burns, so these patients are given enough water to produce a certain amount of urine per hour. However, the phrase “more is not better” applies here. Providing too much fluid, which can have serious side effects such as fluid buildup in the lungs, can be as life-threatening as the burn itself.
Based on guidelines from the American Burn Association, if a patient has burns covering more than 15% of their body, they should be given fluids through an IV (a tube inserted into a vein). Ideally, two large IV lines should be set up in non-burnt skin, and a central vein should be accessed if possible. If necessary, IV lines can even be set up through burnt skin to avoid delays in treatment.
The role of using albumin, a protein in the blood, in treating burn injuries is not clear. Despite seeming sensible due to its role in balancing fluids in the body, using albumin has been linked with higher death rates in some studies.
Preparing for Burn Fluid Management
There are several methods used by doctors to treat burns, but the most common ones are based on two approaches known as the Parkland and the Modified Brooke formulas. According to these methods, a type of fluid called lactated Ringer’s solution is given to the patient, and the amount ranges from 2 to 4 milliliters per kilogram of the patient’s body weight per day, depending on the burn area percentage.
When treating children with burns, doctors need to consider some key facts. Unlike adults, children have a different ratio of body surface area to body mass. This means that compared to their body size, children have more skin, which makes them more sensitive to cold temperatures and they could need more fluid when they have a burn. Plus, the areas of the body covered by skin are different in children. For example, children’s heads are relatively larger, even up to 18% of their total body skin area, and their legs are smaller.
There is another critical difference when treating burns in children versus adults. Doctors typically start fluid replacement when burns cover 15% or more of a child’s total body skin area. But for adults, this usually starts when burns cover 20% or more of their total body skin area. This is an important distinction to make sure that each patient gets the most appropriate treatment.
How is Burn Fluid Management performed
There are two types of fluids that can be used when treating burn injuries: crystalloids and colloids. Crystalloid fluids don’t expand in volume as much as colloid fluids do, but they’re affected by the increased leakiness of the blood vessels that happens early in a burn injury. Colloid fluids can move out of the blood vessels into nearby tissue, causing a shift in the balance of fluids that can make the body’s “third space” (the area outside of the blood vessels and cells) expand.
A research study by Perel and colleagues found that in controlled experiments, there’s no proof that using colloid fluids reduces the risk of death more than using crystalloid fluids in burn treatments. Colloid fluids are also more expensive. Because of this, colloid fluids aren’t commonly used, and crystalloid fluids have become the go-to choice for handling burn injuries.
The Parkland formula, developed in 1968 by Dr. Charles Baxter, is the most widely recognized guide for replacing fluids in burn injuries. It suggests that 2 to 4 milliliters of Ringer’s Lactate (a type of crystalloid fluid) per kilogram of a patient’s weight per percentage of burned body surface area should be used. Half of this amount should be given in the first 8 hours, and the rest should be given over the next 16 hours. However, this formula may not be reliable in calculating body surface area accurately in children and obese patients.
Burn injuries are common and can lead to death, especially in children. Since children have smaller amounts of circulating blood, it’s crucial to replace their lost fluids quickly. Adults’ guidelines have to be adjusted for children because the distribution of their body surface area is different. A few recent surveys showed that about 75% of emergency department healthcare professionals use the Parkland formula for managing children with burn injuries. However, other formulas that take into consideration the child’s body surface area (like the Galveston and Cincinnati formulas) are also used.
The Evans formula and the Brooke formula are other methods developed in the 1950s to calculate fluid replacement in burn injuries using both the patient’s weight and burned surface area. Ringer’s lactate is generally recommended for initial fluid replacement in all age groups, but infants may also need glucose because they have limited amounts of stored sugars. Therefore, pediatric burn replacement fluid formulas often include the estimated fluid replacement (EFR) and added maintenance fluids (MF) with or without glucose, depending on the child’s age. The threshold for using the adult formula generally falls between 30 to 50 kg.
Currently, the Cincinnati formula and the Galveston formula are widely used for pediatric burns, but there is yet to be a study comparing these two formulas. The goal in treating pediatric burn injuries is based on the amount of urine the child produces: 1 milliliter per kilogram per hour for children under 30 kg, and 0.5 milliliter per kilogram per hour for children over 30 kg. However, using urine output alone as a measure of treatment effectiveness can be controversial and sometimes not accurate. Some experts suggest that the treatment goals for infants should also include their general alertness, physical examination results, pulse, and systolic blood pressure. Other treatment end-points to be considered in the pediatric population are lactate levels, invasive measures of blood flow, and central venous pressures (pressure of blood in the central veins). These areas of burn injury fluid replacement continue to be researched for both children and adults.
Possible Complications of Burn Fluid Management
Patients who have been burned often arrive at burn treatment centers overly hydrated. Sometimes first responders or less experienced doctors mistakenly give too much fluid, meeting the requirements for 8 hours of the Parkland burn formula (a method used to calculate fluid needs for burn patients) in as little as 1 to 2 hours.
Sometimes, too much fluid can be harmful to a burn patient. This situation, known as “fluid creep,” can lead to a condition where there is too much water in the body’s tissues. This can affect the lungs or brain, or create a condition known as compartment syndrome of the limbs or abdomen. Compartment syndrome is a painful and potentially serious condition caused by pressure buildup from internal bleeding or swelling of tissues. This problem of fluid overload has become a global concern and is caused by several factors. This includes recent changes to the Parkland formula, the effects of targeted fluid resuscitation efforts, the tendency to give too much fluid at the scene of the injury, and not efficiently balancing fluid administration afterward. Certain factors can also make burn patients more likely to need more fluids, such as inhaling too much smoke, delays in getting fluids, having multiple injuries, or being injured by high-voltage electricity.
Because of this, it’s crucial to recalculate fluid needs hourly. The fluid rate should not be increased by more than 20% to 25%. Medical personnel are usually aware to increase fluid rates when urine output is less than 30 ml per hour, but are less likely to reduce the rate when urine output rises above the recommended maximum of 1 ml/kg per hour. These adjustments should be made accordingly, and one study showed that the adjustment rate was only correct 35% of the time.
Moreover, it has been suggested that using urine output as the only measure of a patient’s hydration level might not be as precise as using other measures, such as base deficit and lactic acid levels. These measures can give a better indication of the fluid balance in a patient’s body. Different beliefs and conflicting research contribute to a wide range of treatments for burn patients among different doctors.
Patients with burns wrapped around a limb may experience a “tourniquet effect” due to the forming scab, which can cut off blood flow. In these cases, immediate action may be needed to relieve pressure even before fluid replacement. However, such situations are unusual, except for cases of electrical burns, burns with an underlying broken bone, or burns with a blood vessel injury.
What Else Should I Know About Burn Fluid Management?
Years of research on burn injury and patient recovery have shown the critical importance of quick fluid replacement for the survival of these patients. With effective fluid replacement procedures now in place, there has been a decrease in the number of patients who pass away within the first 48 hours of experiencing severe burns.
It’s important to note that not receiving enough fluids soon after a burn injury can lead to more severe burns and a prolonged state of shock, both of which can increase the chances of mortality. Hence, rapid and adequate fluid resuscitation is key to reducing these risks and supporting optimal recovery after severe burn injuries.
