What are the pathophysiological risks of hyperbaric oxygen therapy (HBOT)?

Pathophysiological Risks of Hyperbaric Oxygen Therapy

Hyperbaric oxygen therapy carries specific pathophysiological risks including barotrauma, oxygen toxicity, and potential exacerbation of certain underlying conditions, though serious adverse events remain relatively uncommon when proper patient selection and protocols are followed.

Direct Physical Risks from Pressure and Oxygen Exposure

Barotrauma

• Middle ear and sinus barotrauma are the most common complications, occurring from pressure changes during compression and decompression phases 1
• Pulmonary barotrauma can occur if patients fail to equalize pressure properly, though this is less common with proper technique 1

Oxygen Toxicity

• Central nervous system oxygen toxicity can manifest as seizures, though this occurs infrequently with standard treatment protocols 1
• Pulmonary oxygen toxicity may develop with prolonged or repeated exposures, causing inflammatory changes in lung tissue 2
• Transient myopia is a common but reversible side effect from oxygen-induced lens changes 1

Oxidative Stress-Related Complications

• Increased reactive oxygen species (ROS) in blood and tissues can cause cytotoxic effects, particularly problematic in patients with pre-existing oxidative stress conditions 3
• Cataract formation has been documented as a potential long-term complication from cumulative oxidative damage 3

Ocular Complications

Progressive Eye Disease Risks

• Age-related macular degeneration may be exacerbated by HBOT-related oxidative stress, as the retina is particularly susceptible due to high oxygen consumption 3
• Keratoconus progression could theoretically worsen, as this condition involves oxidative stress and antioxidant deficiencies that may be compounded by additional ROS exposure 3
• Retinopathy risks increase in susceptible patients, as oxidative stress plays a major pathogenetic role and HBOT may amplify these processes 3

Cardiovascular and Systemic Risks

Hemodynamic Effects

• Hypotension can occur, particularly with moderate hypothermia protocols (32°C-33°C) when combined with HBOT 1
• Cardiac arrhythmias have been reported, especially in critically ill patients or those with pre-existing cardiac conditions 1

Hematologic Changes

• Thrombocytopenia may develop during treatment courses 1

Infectious and Pulmonary Complications

Respiratory Risks

• Pneumonia risk increases in critically ill patients undergoing HBOT, particularly those requiring mechanical ventilation 1
• Claustrophobia can limit treatment tolerance in susceptible individuals 1

Special Population Considerations

Critically Ill Patients

• Risk/benefit assessment is mandatory before including HBOT in ICU patient care, as the therapy may further compromise already unstable patients 4
• Patient monitoring and treatment should never be altered or stopped due to HBOT requirements; any adverse effects must be strictly evaluated and mitigated 4
• Transport to hyperbaric facilities poses additional risks for unstable patients 4

Pregnancy

• HBOT has been administered safely to pregnant women with carbon monoxide poisoning, though no prospective efficacy studies exist 1
• Fetal distress and death remain concerns in the underlying condition (e.g., CO poisoning) rather than from HBOT itself 1

Condition-Specific Contraindications and Risks

Acute Ischemic Stroke

• HBOT is explicitly contraindicated for routine acute ischemic stroke (Class III: No Benefit), as studies show no improvement in outcomes and potential harm 5
• The only exception is ischemic stroke caused by air embolism or decompression sickness, where HBOT is the standard treatment 1, 5

Burn Patients

• Patients with significant body burns may be at greater risk for mortality from burns than from concurrent conditions like CO poisoning 1
• The decision to use HBOT should be deferred to experienced burn surgeons, as transport and treatment may interfere with critical burn care 1

Resource and Logistical Risks

Treatment Burden

• High cost and resource utilization without clear documentation of need represents a risk of inappropriate resource allocation 6
• Time-intensive treatment protocols (weeks of daily sessions) may delay or interrupt other necessary medical management 1
• Treatment requires proximity to specialized facilities, potentially creating delays in care for patients requiring transport 1

Risk Mitigation Strategies

Patient Selection

• Comprehensive pre-treatment evaluation is essential, particularly for ocular diseases where oxidative stress plays a pathogenetic role 3
• Patients with general frailty and multiple comorbidities should be carefully screened, as they face increased adverse event risks 1
• Antioxidant dietary supplementation may be indicated in conjunction with HBOT when co-existing diseases could be adversely affected by oxidative stress, unless it interferes with therapeutic benefits 3

Facility Requirements

• Hyperbaric chambers for ICU patients must be specifically designed and fully equipped to allow continuation of monitoring and treatment 4
• All devices introduced into chambers must be evaluated, tested, and acknowledged as safe for hyperbaric environments 4
• Standard and emergency procedures should be tested and documented before implementation 4