Hyperbaric Oxygen Therapy: An Evidence-Based Primer for Emergency Physicians

Hyperbaric Oxygen Therapy: An Evidence-Based Primer for Emergency Physicians

Margot Samson MD ⁎ , Michael Gottlieb MD †, Christopher Logue MD * , Daniel Popa MD, PhD * - The Journal of Emergency Medicine Volume 70, March 2025, Pages 35-44
Oct 16, 2025
Hyperbaric Oxygen Therapy: An Evidence-Based Primer for Emergency Physicians
Elsevier

The Journal of Emergency Medicine

Volume 70, March 2025, Pages 35-44

The Journal of Emergency Medicine

Clinical ReviewsHyperbaric Oxygen Therapy: An Evidence-Based Primer for Emergency Physicians

Author links open overlay panelMargot Samson MD ⁎, Michael Gottlieb MD †, Christopher Logue MD , Daniel Popa MD, PhD

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Abstract

Background

Hyperbaric medicine is a subspecialty that many emergency physicians may not encounter frequently in their daily practice. As such, we hope to provide a review, where we present an overview of hyperbaric oxygen therapy, complications from the therapy, and a description of how the treatments are administered. We also discuss seven emergency indications that may benefit from transfer to a hyperbaric facility for treatment.

Objective of the Review

Our aim is to provide an overview of hyperbaric oxygen therapy as it pertains to an emergency physician. We hope that this review will help emergency physicians identify conditions that may benefit from transfer to a hyperbaric facility.

Discussion

We discuss seven emergency conditions that may benefit from transfer to a hyperbaric facility for management—decompression sickness, arterial gas embolism, central retinal artery occlusion, carbon monoxide poisoning, crush injury, necrotizing soft tissue infection, and symptomatic anemia. We also describe special considerations for how to transfer patients needing evaluation by a hyperbaric physician.

Conclusions

This review aims to describe hyperbaric oxygen therapy, identify conditions that may benefit from treatment with hyperbaric oxygen, and discuss management of patients with those conditions as it pertains to an emergency physician.

Introduction

Hyperbaric oxygen therapy (HBOT) is oxygen therapy under pressure administered via a hyperbaric chamber. There are thousands of hyperbaric chambers in the United States, but of those, only 156 are accredited by the Undersea and Hyperbaric Medical Society (UHMS), which is supported by the Food and Drug Administration. Of all the chambers contacted in a recent survey, only 43 (11.9% of respondents) reported that they were equipped to manage medical emergencies (1,2).

Though rare, there are several medical conditions that benefit from emergent HBOT—decompression sickness, arterial gas embolism, central retinal artery occlusion, carbon monoxide poisoning, crush injury, necrotizing soft tissue infection, and symptomatic anemia which will further be described in this article. Many of these conditions are relatively uncommon, and many facilities do not have hyperbaric capabilities, so a typical emergency physician may not be as familiar with diagnosing and treating these patients. This article aims to help emergency physicians better diagnose, treat, and potentially transfer hyperbaric patients. Of note, this review will not cover less emergent conditions that may benefit from rapid adjunctive HBOT, including but not limited to diabetic foot infections, radiation injury, compromised flaps and grafts, and acute thermal burns.

A narrative review was conducted via PubMed and Google scholar for articles about HBOT and the indications described in this review. The 14th edition of the UHMS Hyperbaric Medicine Indications Manual was also reviewed, and primary literature from that reference was accessed separately as referenced throughout. Specifically, articles published from 1960 to 2023, either written in or translated to the English language were used. Preference was given to more recent meta-analyses and randomized clinical trials.

HBOT is a medical intervention where a patient breathes 100% oxygen while inside a hyperbaric chamber that is pressurized to greater than sea level pressures (1.0 atmosphere absolute [ATA]) (2). That oxygen diffuses primarily into plasma, since hemoglobin is nearly entirely bound with oxygen at room air. The hyper-oxygenated blood then distributes to all the tissues that receive arterial blood flow. The increased oxygen, as well as the increased pressure, are both essential in treating a variety of emergent and nonemergent conditions.

Per guidelines from the Undersea and Hyperbaric Medical Society (UHMS), the pressures in a hyperbaric chamber must equal at least 1.4 ATA for clinical purposes, and most treatments are done with at least 2.0 ATA, double the pressure at sea level (2). The patient then breathes 100% oxygen at pressure. The increased pressure increases the amount of oxygen dissolved in the blood via Henry's law, which states that the amount of dissolved gas in a liquid is directly proportional to the partial pressure of that gas (3). This in turn increases the oxygen supply to tissues, which accelerates the wash-out of other gases, such as carbon monoxide or nitrogen, via an increased diffusion gradient (4). HBOT also works via Boyle's law, which states that the pressure of a gas and its volume are inversely proportional. However, this mechanism is thought to play a much smaller role in treating conditions with gas bubbles than the increased diffusion gradient (5). In addition, the hyperoxia leads to an increased amount of reactive oxygen species and reactive nitrogen species, which triggers several cellular pathways ultimately leading to increased angiogenesis, diminished inflammatory response, and increased postischemic tissue survival (5). Furthermore, hyperoxia can assist in blunting ischemia-reperfusion injury, as hyperbaric oxygen can modulate the neutrophil-endothelial interactions. Hyperoxia also has important antimicrobial properties, which can help in treating necrotizing infections (4).

HBOT, like many other medical treatments, carries some risks but is generally quite safe. These vary in terms of incidence and seriousness, and include middle ear barotrauma, ear and sinus pain, temporary myopia, possible acceleration of cataract formation, confinement anxiety, hypoglycemic events, pulmonary barotrauma, pulmonary oxygen toxicity, and oxygen toxicity seizures (6).

The most common side effect reported by patients is otalgia, which can lead to otic barotrauma. The pressure changes during HBOT require patients to equalize the pressure in their middle ear. Inability to equalize can lead to tympanic membrane rupture. This otic barotrauma can be avoided by good patient coaching (2,6). In the rare case that a patient cannot equalize middle ear pressures, myringotomy or pressure equalization tube placement can be performed. Sinus barotrauma is another possible side effect seen in patients with obstructed sinus drainage, typically from mucus but potentially from an anatomical anomaly such as a polyp. Sinus barotrauma can usually be prevented with use of decongestants prior to HBOT. Among patients with diabetes, HBOT can cause reductions in blood glucose, potentially causing symptomatic hypoglycemia. These events are usually prevented with good patient education, close pre- and post-treatment glucose monitoring, and glucose repletion. If a patient has an implantable device, such as a pacemaker, the device should be checked prior to HBOT to ensure it is safe and can continue to work when undergoing pressure changes (3). Confinement anxiety may occur and can be alleviated with anxiolytic medications and sedation as needed (6). Pulmonary barotrauma can occur in patients with asthma or chronic obstructive pulmonary disease. In those cases, alveolar air trapping can occur and cause alveolar rupture, which can lead to a pneumothorax or arterial gas embolism. This is extremely rare, and risk is mitigated with pretreatment chest imaging and long depressurization times. An untreated pneumothorax is a contraindication to HBOT (3).

Meanwhile, breathing high concentrations of oxygen also can have side effects. Oxygen partial pressures greater than 1.6 ATA produce a risk of seizure among all patients, regardless of prior seizure history or other risk factors. During typical HBOT treatment protocols, the incidence of oxygen seizure is between 0.01% and 0.05% (2,6,7). Should a nonepileptic patient suffer a seizure during HBOT, the consequences are generally minimal and do not preclude further HBOT. Antiepileptics generally have no role in treating these seizures (2). A second risk of high oxygen is pulmonary oxygen toxicity which can lead to a clinical picture similar to acute respiratory distress syndrome (ARDS). This is rare, and in our experience, more commonly develops if an intubated patient cannot be weaned down from high concentrations of oxygen in the times between HBOT treatments (2,7). Furthermore, after many HBOT treatments, typically for nonemergent conditions, some patients report myopia that ultimately reverts to their baseline visual acuity within a few weeks of completion of treatment (2). Last, extensive HBOT treatments (50+) may accelerate cataract formation, via oxidative stress and protein denaturation (8).

HBOT occurs in either monoplace or multiplace chambers. Monoplace or single-person chambers, are more common around the country and are present in many hospitals as well as outpatient clinics. They are small, cost-efficient, and do not require an inside attendant to staff. The chamber itself is pressurized and filled with oxygen, so the patient does not wear a separate mask during treatment. However, disadvantages of monoplace chambers include patient isolation, difficulty monitoring critically ill patients, and increased challenges administering critical care. On the other hand, multiplace chambers are larger, more expensive, and require more staffing (9). These chambers, though, are typically better suited for critically ill or unstable patients as well as pediatric patients, as an attendant can administer critical care bedside as needed throughout the duration of the treatment. Multiplace chambers compress air, so patients must wear a mask or hood that delivers the oxygen to them for the duration of the treatment. Multiplace chambers can also be used to treat several patients at once, as long as all patients are undergoing similar treatment parameters (2,9).

The pressure, time at pressure, frequency of treatment, and total number of HBOT treatments all depend on the specific hyperbaric indication. Typically, treatments last from 90 min to two hours (longer for certain indications, including arterial gas embolism and decompression sickness), can occur one to three times per day, and use pressures of 2.0–3.0 ATA (10). HBOT is usually administered according to treatment tables and protocols, many of which are based on the U.S. Navy Treatment Tables (11).

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Section snippets

Discussion

While HBOT is perhaps best known for treating diving-related emergencies, they remain rather rare and do not represent the majority of emergency HBOT patients. A review of diving emergencies by the Diver's Alert Network (DAN) in 2018 led investigators to report an estimated average fatality rate of 1.8 per 100,000 divers per year (12). Most divers will experience an injury or other emergency that merely occurred while diving, and they will frequently present to an emergency department for

Conclusion

This paper describes seven emergency indications where treatment with HBOT should be considered. Access to hyperbaric facilities equipped to manage emergencies may be limited, so knowing where those facilities are located and when to transfer a patient to one of those facilities is important. We hope that this paper helps emergency physicians feel more comfortable with the diagnosis and early management of the conditions described.

Article Summary

1. Why is this topic important?

Hyperbaric medicine is a

CRediT authorship contribution statement

Margot Samson: Writing – review & editing, Writing – original draft, Conceptualization. Michael Gottlieb: Writing – original draft, Conceptualization. Christopher Logue: Writing – original draft, Conceptualization. Daniel Popa: Writing – original draft, Conceptualization.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References (50)

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Written by Margot Samson MD ⁎ , Michael Gottlieb MD †, Christopher Logue MD * , Daniel Popa MD, PhD * - The Journal of Emergency Medicine Volume 70, March 2025, Pages 35-44