Acute Traumatic Ischemia Hyperbaric Evaluation and Treatment

Anatomy and Physiology

After an acute traumatic limb injury, vascular damage produces bleeding into surrounding tissues, with subsequent coagulation and stasis in the vessels. Cellular hypoxia develops, impairing the ability to maintain adequate intracellular water and meet metabolic demands. The resulting edema increases tissue pressure, further exacerbating ischemia and hypoxia, leading to additional cell death and extravascular fluid accumulation. Restoration of blood flow precipitates ischemia-reperfusion injury. Endothelial injury permits fluid extravasation, edema formation, and progressive obstruction of blood flow by neutrophils adhering to the damaged vessel wall.

HBOT mitigates these acute cellular changes; vasoconstriction reduces blood and plasma inflow to the injured region. However, elevated plasma oxygen concentration produces a net increase in oxygen delivery. Reduced edema improves oxygen diffusion distance. HBOT also decreases neutrophil adhesion to the injured endothelium, attenuating ischemia-reperfusion injury.[5]

Indications

Emergency surgical treatments, including revascularization and fracture stabilization, should precede consideration of HBOT. In less urgent cases, HBOT may assist the surgeon in distinguishing viable from nonviable tissue, thereby minimizing tissue loss and reducing the risk of amputation. The decision to initiate HBOT and determine treatment frequency requires close collaboration with the surgeon. Treatment should be guided by the type and severity of injury, as well as patient-specific host factors.

Using an objective grading system, such as the Gustilo open-fracture crush injury classification, combined with a host factor function score incorporating age, smoking status, steroid use, ambulation status, and cardiovascular and renal function, improves patient selection and treatment planning. Even milder injuries in compromised hosts may benefit from HBOT as an adjuvant therapy. Utilization review of HBOT constitutes an important component of clinical care. Review is most effective when conducted collaboratively by surgical and hyperbaric teams after a predetermined number of HBOT sessions.[6][7]

Contraindications

No direct contraindications to HBOT exist in acute traumatic peripheral ischemia unless therapy delays emergent, limb-saving procedures, such as revascularization or fasciotomy for established compartment syndrome. Absolute contraindications are rare and include unrelieved tension pneumothorax.

Equipment

A pressure vessel and 100% oxygen deliver the therapeutic effects of HBOT to the body. There are two types of pressure vessels: monoplace and multiplace chambers. Monoplace chambers typically accommodate a single patient and consist of a transparent acrylic tube with access through a metal door at one end. In monoplace chambers, the chamber is pressurized with 100% oxygen, which the patient breathes directly. Some monoplace chambers include a separate breathing mask to provide air during prescribed air breaks. Equipment such as ventilators, infusion pumps, and physiologic monitoring devices can be integrated to support high-acuity care. Monoplace chambers may be installed in a standard hospital room and connected to the hospital’s oxygen and air supply.

Multiplace chambers are constructed from steel with acrylic viewing ports and can accommodate 2 to 20 patients. These chambers are pressurized with air, while patients breathe oxygen through a tight-fitting mask or a hood sealed around the neck with a rubber neck dam. Patients breathe the chamber air during air breaks. Multiplace chambers are typically large complexes equipped with compressors, reserve air, and oxygen tanks. 

Both monoplace and multiplace chambers require specialized manufacturing and installation in accordance with fire protection codes, such as the National Fire Protection Association (NFPA) 99 in the United States (US). Facility accreditation for hyperbaric programs is recommended and is available through the Undersea and Hyperbaric Medical Society in the US and select international locations. Transcutaneous oximetry can measure tissue oxygenation during ambient air exposure and HBOT. A tissue oxygen level exceeding 200 mm Hg during treatment demonstrates a positive predictive value of 0.88 for wound healing.

Personnel

For monoplace chambers, a single specially trained outside attendant may conduct and supervise up to 2 simultaneous HBOT sessions and must remain in continuous attendance outside the chambers. Multiplace chamber operations require both outside and inside specialty-trained attendants. Inside attendants breathe compressed chamber air and are at risk for decompression illness, similar to scuba divers. Strict safety protocols and procedures are required to minimize this risk. An outside chamber operator pressurizes the chamber and maintains constant communication with inside attendants.

A safety director is responsible for the maintenance and safe operation of the hyperbaric facility. A specialty-trained hyperbaric physician prescribes and supervises the pressure, duration, and gas composition of HBOT and examines patients before and after each session. Specialty-trained hyperbaric clinicians and nurses provide wound care, administer medications, and educate patients and families.[8]

Preparation

Safety procedures are required to minimize the introduction of static electricity, fuel, and ignition sources into the hyperbaric environment, thereby reducing fire risk. All personnel inside the chamber must wear cotton or cotton-blend sheets and scrubs. Oily substances and alcohol are prohibited, and ignition sources are not permitted. Myringotomy tubes may be necessary in rare instances where patients have difficulty equalizing middle-ear pressure during compression.

Dressing changes and wound debridement may be required prior to chamber entry, depending on the patient’s injury. Patients requiring monitoring during HBOT must have appropriate sensors applied and connected to pass-through connectors in the chamber hull. Patients requiring medications or infusions may need preparation for specialized infusion pumps. Communication between the primary surgical service and the hyperbaric medical team is essential to ensure safe and effective treatment.

Technique or Treatment

The attending hyperbaric medicine specialist prescribes the duration, pressure, and breathing gas for each patient on the treatment table. In multiplace chambers, the specialist also plans the decompression gas profile for inside attendants. Standard treatment tables for acute traumatic peripheral ischemia include 2 atmospheres absolute (ATA) for 2 hours or 2.4 ATA for 90 minutes. The number of treatments varies depending on the injury type.

A single treatment may suffice to prevent ischemia-reperfusion injury. Crush injuries often require a more intensive schedule of 8 treatments: 1 treatment 3 times a day for 2 days, followed by 2 treatments per day for 2 days, and then 1 treatment per day for an additional 2 days. Impending compartment syndrome is generally managed with 3 treatments: 2 on the first day and 1 on the second day.

Established compartment syndrome requires fasciotomy. However, HBOT remains beneficial postoperatively to address residual tissue ischemia, massive swelling, or nerve injury. Postfasciotomy HBOT may require twice-daily sessions for up to 7 days. Delayed HBOT during the healing process may necessitate additional treatments, depending on wound extent and patient comorbidities.

Complications

HBOT is generally well tolerated. Occasionally, patients with difficulty equalizing middle-ear pressure develop barotrauma of the ears. Management usually involves nasal decongestants, and myringotomy tube placement by an otolaryngologist is rarely required. Pulmonary barotrauma is very uncommon. However, the possibility should be considered if patients develop chest pain during ascent.

Pulmonary and cerebral oxygen toxicity is typically not a concern with the relatively short exposures used for acute traumatic peripheral ischemia, but remains a potential risk. Neurologic oxygen toxicity may result in seizures. Convulsions may be prevented with antiepileptic medications or managed during the episode with benzodiazepines. Reducing treatment depth or oxygen concentration usually resolves these episodes. Introducing a 5-minute air break during treatment further minimizes the risk of oxygen-induced seizures.[9]

Changes in eye refraction generally occur only after prolonged HBOT courses of 40 to 60 sessions and are often reversible. Blood glucose levels may decrease during or after treatment in patients with diabetes, necessitating careful monitoring.[10] Individuals with poorly controlled hypertension also require monitoring and appropriate management during HBOT sessions.[11]

Clinical Significance

Acute traumatic peripheral ischemia can be devastating, potentially resulting in permanent loss of limb or function. The cost of amputation, including rehabilitation and loss of productivity, substantially exceeds the cost of limb salvage and reconstruction, even when HBOT is included, which accounts for approximately 10% of the total expense.[12] HBOT represents an often-overlooked adjunct to surgical management. This intervention interrupts the cycle of edema, ischemia, and hypoxia and mitigates the harmful effects of ischemia-reperfusion injury. Despite its benefits, HBOT is often reserved for treating late complications rather than being applied early, when it is most effective at reducing tissue loss.[13][14][15][16]

Enhancing Healthcare Team Outcomes

The management of acute traumatic peripheral ischemia is complex and challenging. Trauma surgeons and orthopedic specialists direct care, while additional healthcare team members provide expertise to enhance patient outcomes. The Undersea and Hyperbaric Medical Society has proposed a treatment algorithm to identify patients most likely to benefit from HBOT. The algorithm incorporates trauma type and severity, based on the Gustilo classification, as well as patient host factors that may influence therapeutic decisions. Optimal treatment planning for severe traumatic injuries relies on interprofessional collaboration.

Nursing, Allied Health, and Interprofessional Team Interventions

HBOT-trained nurses are essential members of the healthcare team for both monoplace and multiplace chamber operations. Responsibilities include patient care tasks, such as medication administration, blood glucose monitoring, and wound dressing. Multiplace chambers allow nurses to attend to patients within the chamber. In contrast, monoplace chambers position the patient inside, with the technologist supervising from outside. Certified hyperbaric technicians prepare and maintain the technical components of the hyperbaric program to ensure safety and operate the chambers during treatments.

Nursing, Allied Health, and Interprofessional Team Monitoring

Hyperbaric nurses and technicians monitor patients during HBOT by direct visual observation and verbal communication or by cameras and display screens. Vital signs are measured with appropriate sensors connected via specialized pass-throughs in the chamber hulls.