Hyperbaric Treatment of Thermal Burns

Anatomy and Physiology

Thermal burns are classified by the depth the tissue injury. There are four classifications set by the American Burn Association:

Superficial: Involve the epidermal layer of the skin. These injuries do not blister but can be painful. They usually self-resolve within 1 week.

Partial Thickness (second-degree): Involve the epidermal layer and parts of the dermal layer. Superficial partial thickness burns blister and are painful but resolve within 21 days and usually do not cause scarring. Deep partial thickness burns always blister and cause damage to hair follicles and glandular tissue. Deep partial thickness burns are extremely painful. These burns can get infected and may need to be grafted depending on the extent of the injury. These injuries take up to 9 weeks to heal and will form hypertrophic scarring.

Full Thickness (third-degree): These burns go through the entire dermal layer and frequently injure subcutaneous tissue. Burn eschars, or the denatured dermal layer, is intact acutely. The wound may be anesthetic due to the necrotic nature of the burn. The appearance can be waxy or grey to black. The eschar of the burn will eventually fall off, revealing a bed of granulation tissue. If a full thickness burn does not undergo surgery, it will heal by contracture. These burns never spontaneously heal. See Image. Thermal Burn, Third Degree.

Extension into deep tissues (fourth-degree): These burns involve the underlying soft tissue that may involve muscle or bone. These injuries may be life-threatening and need to be treated immediately.

Indications

Hyperbaric oxygen therapy is indicated for burns that extend into the dermis and beyond. Each case may vary, but if a patient has an inhalation injury, impaired wound healing, extensive edema, or a large area of skin involved, HBO therapy would be a good adjunctive therapy to add. If a patient has received a skin graft or flap, HBO has shown to improve the success of graft placement.[6]

Technique or Treatment

If used, HBO treatment should be initiated as soon as possible after the injury. Three treatments in the first 24 hours is suggested, and twice daily after that. Sessions are 90 minutes in length at 2.0 ATA to 2.4 ATA and should be continued for 20 to 30 sessions, although the number of treatments depends on the clinical extent of the injury and response to treatment. Patients are monitored in the chamber with blood pressure (BP) cuffs approved to use in monoplace chambers. Ventilator support may be given in the chamber, which is common in patients with who sustained an inhalation injury. Fluid management is crucial in burn patients and needs to be initiated before HBO therapy is started. Several liters of fluid may be needed in the acute phase of the injury, and pumps may be needed to overcome the chamber pressure during HBO treatments.[7]

Complications

Though hyperbaric therapy is generally well tolerated, it is important to consider potential complications that can arise in patients receiving treatment. Barotrauma to hollow organs of the body is the most frequent side effect for which patients should be carefully monitored. The most common barotraumatic injury is middle ear barotrauma, which includes middle ear effusions and tympanic membrane rupture, with an incidence of about 2%. This side effect can mitigated with careful patient instructions regarding autoinflation techniques during treatment.[8]

Barotrauma can also involve the sinuses, and is typically found in patients who have upper respiratory infections or allergic rhinitis. Patients should be carefully screened for these preconditions and may even be given antihistamines or nasal decongestants to mitigate potential complications during therapy sessions.[8]

Pulmonary barotrauma, though less common, is another important complication to keep in mind. Before hyperbaric therapy is initiated, patients should be fully evaluated for a pre-existing pneumothorax, which should be managed prior to starting treatment. In fact, an untreated pneumothorax is the only absolute contraindication to hyperbaric therapy.[9]

Systemic oxygen toxicity from hyperbaric therapy can also cause a rare, yet concerning side effect: seizures. Hyperic induced seizures have an incidence of about 0.011%, according to a retrospective analysis of 2,334 patients.[10] They have also been associated with patients receiving certain medications including insulin, steroids, thyroid replacement therapy and sympathomimetics, and thus patients on these medications should be carefully monitored during sessions.[11] If seizures do occur, they should be managed acutely by reducing the Fi02 concentration to that of air (21%), administering anticonvulsant therapy, and stopping hyperbaric treatment as soon as possible.[9]

Clinical Significance

In summary, HBO therapy first 24 hours of burn has shown to:

1. Decrease edema by vasoconstriction and decrease the chance of burn shock
2. Decrease wound infections
3. Promote epithelialization
4. Increase the viability of skin flaps and grafts
5. Be effective against carbon monoxide and smoke inhalation injury
6. Reduce fluid requirements of the patient
7. Counteract ischemia in tissue by raising oxygen levels hypoxic tissue to supraphysiologic levels

Twenty-four hours after thermal burn injuries, HBO has shown to:

1. Relieve a paralytic ileus  
2. Decrease incidence of Cushing’s ulcers
3. Reduce hypertrophic scarring and ulceration
4. Counteracts burn encephalopathy/cerebral edema
5. Reduce the length of hospital stay
6. Reduce the need for surgery

Enhancing Healthcare Team Outcomes

Thermal burns are best managed by an interprofessional team, including a wound care nurse. While the treatment in most patients is supportive, recent evidence indicates that HBO therapy may help wounds heal faster. However, the vascular status of the wound must be assessed because without adequate blood supply, HBO therapy may not always work and empirically sending every patient for HBO therapy is not cost effective.