To follow up the article on The Basics of Burns we’re diving into the nursing care of burns.
Pathophysiology of Burn Injury
An important concept to understand with burns is that in larger burns (generally around 30% TBSA), the body’s response to the injury is not just localized to that area. There is a systemic response that increases in severity in proportion to the extent of the injury. Bigger burns mean your patient is “bigger sick.”
First, let’s talk about what happens to the skin itself. With burn injury, the amount of damage depends on the duration of exposure and the temperature, with temps above 44-degrees Celsius causing cell necrosis. Cellular damage continues until the heat source is removed and the tissue is cooled to normal levels. There are three zones of burn injury:
- Zone of coagulation – This is the zone with the maximum damage. Tissue loss in this zone is irreversible.
- Zone of stasis – The zone of status surrounds the zone of coagulation and is characterized by decreased tissue perfusion. It is possible to save this tissue with prompt treatment. Complications such as infection, hypotension, and edema can render this tissue unsalvageable.
- Zone of hyperemia – This is the outermost area of the injury where tissue has more perfusion. Unless there is a severe complication such as prolonged hypoperfusion or severe sepsis, this tissue should recover.
Phases of Burn Management
There are three phases of burn management.
- Resuscitation phase – the time from the initial injury and continues until capillary integrity has returned to baseline and the patient’s fluid losses have been restored. When spontaneous diuresis occurs, this is the signal that the capillary membrane has regained its integrity and is no longer ‘leaking’ fluid into the interstitial space.
- Acute phase – the time from diuresis onset to burn wound closure.
- Rehabilitative phase – focus on this phase is on continued wound healing, prevention of contractures, minimizing or preventing scars, managing a functional disability, and psychosocial support for the patient/family.
Burn Center Referral
One of the first things to consider is if your patient should be referred to a burn center. Ideally, this decision is made in the field, but if a patient with a burn shows up in your hospital, you can use the AmeriBurn website to see the criteria for burn center referral. For example, patients that qualify include those with third-degree burns of any size, partial-thickness burns greater than 10% TBSA, or burns to the major joints, face, hands, feet, perineum, or genitalia. For more details, visit the AmeriBurn website.
Caring for a Patient with a Burn
So how does the body respond to burn injury? Initially, the body is going to work very hard to keep key organs alive. It does this by shunting blood toward the two most important organs – the brain and the heart. The result is diminished blood flow to other organs, which can lead to organ dysfunction and even failure. Additionally, cytokines and other inflammatory mediators released from the site of the injury will have systemic effects (which we’ll talk about further on).
The first 24 to 36 hours after injury is the most crucial in managing the patient with a burn. In addition to determining the size of the burn, it’s also important to determine if the burn is due to thermal, electrical, or chemical sources as each has specific implications. For example, electrical burns will often have extensive underlying damage and chemical burns often have system-wide effects. Additionally, be sure to remove anything potentially constricting, such as watches and rings, as the edema in burn injury can be significant.
Manage the airway – Securing and protecting the airway are the initial priorities in burn injury. Be highly suspicious of airway involvement in burns to the face or if the individual was in an enclosed space.
Provide oxygen – Carbon monoxide poisoning is a key contributor to patient mortality, so the MD will likely order a carboxyhemoglobin level and supplemental oxygen at 100% FiO2. Recall that carbon monoxide binds to the iron ion in heme with an affinity that is approximately 240 times stronger than that of oxygen. Providing high-flow supplemental oxygen shortens carbon monoxide’s hold on that ion as long as the patient is no longer taking in more carbon monoxide.
Manage respirations – Circumferential burns can have a constricting or tourniquet-like effect on the body. When full-thickness burns circle the chest wall, respirations are constricted and compliance is decreased. You’ll want to monitor the patient for shallow, fast respirations and signs of hypoxia. Many patients with circumferential burns to the chest wall will need to be intubated and receive mechanical ventilation. Additionally, an escharotomy could potentially be done to increase chest wall compliance.
Fluid replacement – One of the most significant factors in burn injury is the shifting of fluid. When the tissue is burned, capillaries become more permeable allowing fluid to seep into the surrounding interstitial tissues. Additionally, the sodium-potassium pump mechanism fails, which enables sodium to enter the cell leading to intercellular edema. The overall concept here is the fluid has shifted from the intravascular space into the interstitial and intercellular spaces. This drastically and negatively affects the patient’s hemodynamic balance. The hypovolemia is compounded by an increased insensible water loss that is up to ten times greater than normal. The short version is, patients with significant burn injury are going to be hypotensive due to fluid shifts and fluid losses.
The Parkland formula is the most widely used calculation to determine the volume of fluid each patient requires. To use the Parkland formula you need the patient’s body weight in kg and the % TBSA.
- For adults the calculation is 4ml x % TBSA x body weight in kg = total amount of fluid.
- You give 50% of that fluid over the first eight hours and the remaining 50% over the next 16 hours.
- The total fluid resuscitation infusion runs for the first 24 hours of treatment.
The goal with fluid replacement is to counteract the fluid shifts, correct intravascular hypovolemia, and improve cardiac output and end-organ perfusion. The most commonly used fluid for this purpose is Lactated Ringer’s because its components are similar to that of the extracellular fluid.
Electrolyte Imbalance – The patient with a burn injury is at risk for sodium and potassium imbalances in both the resuscitation and acute phase.
- In the resuscitation phase, monitor for hyperkalemia due to the release of potassium from damaged tissues diminished renal function, and acid-base imbalance. The imbalance is typically resolved once the acid-base balance is restored.
- Monitor for hypokalemia in the resuscitation phase due to hemodilution and fluid/electrolyte losses through the wound itself. In addition to addressing the underlying cause, potassium replacement will be needed.
- Hypokalemia in the acute phase can be due to hemodilution, diuresis, NGT suctioning, vomiting, diarrhea, potassium shifts as acid-base balance improves, and even due to long sessions of hydrotherapy. Just as in the resuscitation phase, you’ll want to address the underlying cause and replace potassium as needed.
- Hyponatremia occurs commonly in the resuscitation phase due to third spacing, fluid/electrolyte losses through the wound itself, vomiting, diarrhea, NGT suctioning, and the use of hypotonic solutions. Treatment involves addressing the underlying cause and may include IV replacement of sodium.
- Hyponatremia in the acute phase is typically due to continued losses through the wound, long hydrotherapy sessions, hemodilution, and diuresis as the fluid shifts back into the intravascular space. In addition to limiting hydrotherapy sessions, the key intervention during this phase is limiting free water intake.
Cardiac function and hemodynamics – Patients with extensive burn injury should be on continuous ECG monitoring. Additionally, you will need to watch the patient closely for signs of hemodynamic compromise and potentially fluid volume overload during the resuscitation stage. The massive third-spacing of fluids can cause pulmonary edema, so keep a close eye on respiratory status as well.
Peripheral blood flow – Edema and circumferential burns can drastically impede blood flow to the periphery. Frequent assessment of CSM is vital to ensure complications are not occurring. Escharotomies may be needed in cases of significantly reduced arterial flow.
Respiratory system – Patients with a burn injury can develop pulmonary edema, respiratory failure, and acute respiratory distress syndrome (ARDS). It’s important to note that ARDS can develop even without direct lung injury or toxin inhalation and can be a result of systemic inflammation and sepsis.
Renal system – Hypoperfusion can lead to acute kidney injury and even acute renal failure. Patients with burns above 15% TBSA should have an indwelling urinary catheter for careful monitoring of urine output. Recall that the goal urine output for an adult is 0.5 to 1 ml/kg/hr. You’ll also be obtaining urine for urinalysis to assess for the presence of myoglobin in the initial phase of treatment. Myoglobin in the urine is due to tissue breakdown and is extremely destructive to the kidneys. It is treated with rapid administration of fluids and osmotic diuretics such as mannitol to flush the renal tubules.
Ongoing renal system monitoring includes BUN and creatinine as well as urinalysis assessing for urine glucose and sodium levels. If an indwelling urinary catheter is in place, the patient is at high risk for infection, so any suspicious urine, fever, or other signs of infection will necessitate a urinalysis to determine if the patient has a UTI.
GI system – Gastric dilation can occur due to paralytic ileus. You will be auscultating bowel sounds as often as every two hours in the initial stages and every four hours throughout the resuscitation phase. If ileus is detected, nasogastric tubes are utilized for gastric decompression and to prevent aspiration. Burn injury patients will also receive what we call “GI prophylaxis” which is the term we use for the prevention of gastric ulcers. This typically involves an H2-receptor blocker such as famotidine, a proton pump inhibitor such as pantoprazole, or sucralfate. Additionally, it is recommended these patients receive enteral nutrition as soon as possible to protect the gastric mucosa, maintain gut motility, and meet the high metabolic demands.
Immunity – Patients with burns are at higher risk for infection, with sepsis and multisystem organ failure being the leading cause of death after the initial resuscitation period has passed. The wound itself is the most common source of infection due to absent tissue integrity and the normal protective mechanisms. The patient’s own bacterial flora can get into the wound, leading to a systemic bloodstream infection. You will take frequent wound cultures, practice superior hand hygiene, wear the appropriate PPE, and inspect wounds at least daily.
Wound care – It goes without saying that burns require often very complex wound care. The basic principles of standard wound care apply here with the goal of keeping the wound moist and free from infection. The advances in burn wound care are complex and warrant an article all their own. Check back soon!
Temperature regulation – Patients with burn injury lose body heat through their wounds, putting them at high risk for hypothermia. Warming blankets, increased temperature in the room, fluid warmers, and lamps can all be utilized to maintain a body temperature of 99.6 – 101-degrees Fahrenheit.
Pain management – One of the key factors in treating patients with burns is managing severe pain. Many patients will receive continuous opioid medication (ex: fentanyl) and possibly also IV anxiolytics (ex: midazolam). As the tissue and skin grafts heal, itching can be problematic. An antihistamine may be prescribed for this purpose.
The key mainstays of the rehabilitation phase are addressing the emotional scars as well as the long-term healing of the wound. For some patients, the rehabilitation phase can last years. Some key factors in this phase are:
- Addressing impaired mobility due to joint involvement and contractures
- Increasing independence with ADLs
- Supporting the patient psychologically
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