Hyperbaric Oxygen Therapy Regimens, Treated Conditions, and Adverse Effect Profile
Hyperbaric Oxygen Therapy Regimens, Treated Conditions, and Adverse Effect Profile
RUNNING TITLE: AN UNDERSEA AND HYPERBARIC MEDICAL SOCIETY SURVEY STUDY
ABSTRACT
Introduction: When administering HBO2, pressures can range from 1.4 atmospheres absolute (ATA) to 3 ATA. While different treatment modalities have been proposed, there is a paucity of literature comparing the effectiveness and risk profile associated with different pressures treating the same condition. Considering the therapeutic divergence, this study aims to survey Undersea and Hyperbaric Medical Society (UHMS) members on pressure modalities and their use in different clinical conditions.
Methods: The study was a voluntary cross-sectional survey administered online and open to healthcare providers who were members of the Undersea and Hyperbaric Medical Society. UHMS itself distributed the survey link. The survey period lasted from November 2022 until January 2023. Data were collected utilizing the Qualtrics platform and analyzed through Microsoft Excel.
Results: A total of 265 responses were recorded. The majority responded utilizing 2.4 ATA (35.2%) as the pressure of choice, followed by 2.0 ATA only (27.1%), and those who changed therapeutic pressure according to the treated condition (26.4%). The overwhelming choice for treatment of osteoradionecrosis (ORN) of the jaw, radiation proctitis/cystitis, diabetic foot ulcer, and chronic osteomyelitis was 2.0 ATA (68.0- 74.9%). Among listed adverse effects, myopia was the most commonly reported complication at 24.4%, followed by barotrauma (14.9%) and confinement anxiety (11.5%).
Conclusions: There is currently little consensus regarding the best treatment modalities for conditions treated with HBO2. As adverse effects appear to be non-negligible, future prospective studies must be conducted weighing the risks and benefits of higher-pressure therapies compared to safer lower-pressure options.
Keywords: complications; demographics; hyperbaric medicine; hyperbaric oxygen; questionnaire
Key points: This study is a survey study conducted online via Qualtrics among Undersea and Hyperbaric Medical Society (UHMS) members to assess utilization of hyperbaric oxygen therapy. Data was collected on respondents’ demographics, therapeutic pressure utilized, conditions treated, recorded adverse events and respondents’ satisfaction with clinical outcomes were analyzed. The study was able to show how providers across the nation utilize HBO2 and their experiences with it.
INTRODUCTION
Hyperbaric oxygen (HBO2) is a non-surgical intervention aimed at promoting wound healing and regeneration. It is currently a mainstay or adjunctive treatment for 14 different medical conditions approved by the Undersea and Hyperbaric Medical Society (UHMS).1 When administering HBO2, pressures can range anywhere from 1.4 atmospheres absolute (ATA) to 3 ATA, though it is recommended that all approved medical conditions be treated at a minimum of 2 ATA.2 Within the range between 2.0 and 3.0 ATA, there exist multiple ATA settings from which a provider can choose. However, there is still no consensus on the ideal pressure when using HBO2.
In the literature, there is divergence on preferred pressure modalities for treating similar conditions. For instance, for diabetic foot ulcer management, while Kessler et al. (2003) advocated for using 2.5 ATA for 90 minutes twice a day, Zamboni et al. (1997) utilized 2.0 ATA for 120 continuous minutes.3,4 These differences in HBO2 pressure options can be due to numerous factors, such as the availability of machines and patient medical history.5 Conclusive recommendations are still vague. While higher pressures yield an increased blood oxygen concentration, therapeutic use of pressures above 3 ATA is limited due to potential oxygen toxicity for patients and decompression sickness in inside attendants.6 The generally accepted theory is that some adverse events can increase as pressure increases, but most of these side effects are benign or transient.7 This begs into question whether or not pressure should be lowered to avoid adverse events or pressures should be maximized as lower pressures could lead to slower therapeutic effects and thus more socioeconomic burden on the patient as it requires more treatments, time, travel, and money.
Considering the divergence in the literature, the purpose of this study was to survey members of the UHMS to see which treatment pressures are most utilized for each condition investigated. This survey will also collect information on adverse effects seen by providers at different ATAs to help better understand HBO2. Additionally, we hope that the results can yield protocols that benefit patients medically and socioeconomically to optimize the patient experience.
METHODS
The study was a voluntary cross-sectional survey administered online and open to healthcare providers who were Undersea and Hyperbaric Medical Society (UHMS) members. UHMS itself distributed the survey link via an anonymous link or QR code. The survey lasted from November 2022 until January 2023, when the survey was promoted thrice to boost more responses. The survey was not translated into other languages, and, thus, members who were not English speaking or could not fill out the survey in English were excluded. Respondents were not offered incentives to complete the survey.
The survey was designed using Qualtrics. Most of the questions in the demographic section were multiple choice with a supplemental “other” choice where respondents could write an open-ended answer if none of the multiple choices were applicable. Data collection included user demographics, therapeutic pressure utilized, conditions treated, and recorded adverse events. Finally, providers’ satisfaction with clinical outcomes was analyzed. A question was also asked to survey the thoughts of a prospective study comparing 2.0 vs 2.4 ATA. Descriptive statistics were then conducted on the data obtained.
RESULTS
A total of 265 physicians responded to the survey. Of the respondents, 261 (98.5%) reported their country of practice. The majority were from the United States (212, 81.2%), followed by Canada (ten, 3.8%), Italy (six, 2.3%), the UK (five, 1.9%), and the Netherlands (four, 1.5%). As there was a predominance of respondents from the US, the state of practice was also analyzed: Texas had the highest number (21, 10.3%), followed by Florida, Georgia (each 15, 7.3%), and then New York (ten, 4.9%). Except for Alaska, Colorado, Montana, North Dakota, Vermont, Washington, and Wyoming, all 50 states, including Washington DC and Puerto Rico, were represented (Figure 1)
The respondents’ practice was primarily in community hospitals (136, 52.3%), followed by academic institutions (65, 25.0%) and private practices (48, 18.5%). Undersea and Hyperbaric Medicine (75, 28.3%) and Wound Care (73, 27.6%) predominated as most of the respondents’ primary specialties. Respondents were asked for their years in practice (<one year, one-five years, five-ten, ten-20, or >20 years) as well as years in hyperbaric medicine practice (<one year, one to five years, five to ten, or >ten years). Almost two-thirds of the respondents had over 20 years in practice (176, 66.4%) and over ten years in hyperbaric medicine practice (184, 69.4%). The highest level of hyperbaric medicine training was also investigated, and it was found that the majority listed a 40-hour introductory course (115, 43.4%) as their highest level of hyperbaric medicine training. This was followed by Undersea and Hyperbaric Medicine Board certification by Practice Pathway (51, 19.3%). Many responded with “Other”, which they later specified as a wide variety of training programs, including an 80-hour introductory course, Certified Hyperbaric Technologist (CHT)/ Nursing/ US Navy medical training, and programs from different countries. Program for Advanced Training in Hyperbaric Medicine (PATH) had the least respondents (16, 6.04%). Further demographic data can be found in Table 1.
Regarding pressure of choice, 2.4 ATA had the most responses (94, 35.2%). However, both 2.0 ATA and the choice “multiple pressures (both 2.0 and 2.4 ATA)” were close (72, 70 respectively). “Other” answers ranged anywhere from 1.5 to 3.0 ATA. When asked about chamber usage, more than half used only monoplace chambers (165, 62.3%), almost a quarter used only multiplace chambers (60, 22.6%), and the rest reported using both (Table 1). If a respondent chose “multiple pressures (both 2.0 and 2.4 ATA)” as their primary pressure(s) of choice, they were subsequently asked based on what reasoning they chose between the two pressures: 70 respondents (26.42% of total respondents) answered, with a majority basing ATA decision on the diagnosis that is being treated (46, 66.3%), followed by based on patient history (ten, 14.5%). Only three respondents stated their decision was based on equipment available, and four based it on objective measurement of O2 delivery. Those who chose "Other" primarily answered with a combination of the choices above and patient comfort (Table 2).
For respondents who utilized multiplace chambers, we asked if they used 2.0 ATA and the reason why. Respondents were given the choice of it based on patient safety, staff safety, both patient and staff safety, or “Other”. Sixty people (22.64 of total respondents) answered the question, a majority selecting “Other” (24, 40.0%). Apart from “Other”, the choice of both patient and staff safety was the most common reason (21, 35.0%), followed by only patient safety (12, 20.0%) and only staff safety (three, 5.0%), Table 2.
When the entire cohort of respondents were asked if they believe that higher treatment pressures can reduce the frequency of treatment and result in better clinical outcomes, results revealed that there was almost an even split among answers: 35.98% answered Yes, 36.50% answered that they were unsure and 28.52% answered No. Concerning conditions treated and respective pressures, for osteoradionecrosis (ORN) of the jaw (both diagnosed and preventative), radiation proctitis/cystitis, diabetic foot ulcer, surgical flap/ skin graft loss, sudden hearing loss, and chronic osteomyelitis, there was an overwhelming majority for use of 2.0 ATA (68.0 - 74.9% of total votes excluding “Do not treat”). This is because individuals responding who utilized both 2.0 and 2.4 ATA responded utilizing primarily 2.0 ATA for the conditions mentioned above. More than half of the responses said they had never treated burns, intracranial abscesses, and severe anemia. There was a mixed variety of responses for the remaining diagnoses.
The initial recommendation on the number of treatments needed for a specific diagnosis was also recorded. The results are depicted in Figure 3. Like Table 1, the same diagnoses had similar rates of not being treated. Air/gas emboli, carbon monoxide poisoning, and decompression sickness all had a majority agreeing upon less than ten treatments (77.7-91.5% of total votes excluding “Do not treat”). Adverse events (AE) were analyzed as well. Among all the listed AEs, based on respondents’ reported experiences, myopia had the highest accounts from respondents, and the highest median percentage observed during treatments (189 counts, 19.0%). This was followed by barotrauma (184, 14.4%) and confinement anxiety (172, 10.3%). The remaining complications can be found summarized in Table 3.
Finally, respondents were asked to assess their satisfaction with the clinical outcomes of HBO2 based on diagnosis (Figure 4). A vast majority felt extremely satisfied or satisfied with the clinical outcomes of their patients. The diagnosis with the highest satisfaction rate was radiation proctitis/ cystitis (134, 67.0% of respondents who treated the diagnosis were extremely satisfied) and osteoradionecrosis of the jaw (preventative and diagnosed) (102, 57.0% and 114, 56.7% respectively). Finally, respondents were asked whether a study comparing 2.0 vs 2.4 ATA would be valuable. More than half thought it would be valuable by answering “Yes” (141, 68.8%). The rest was almost evenly split between either “Unsure” (38, 18.5%) or “No” (26, 12.7%).
DISCUSSION
A large body of literature has proven the benefits of HBO2 in Medicine as both primary and secondary treatment. However, there is a paucity in the literature regarding hyperbaric oxygen practices and treatment modalities employed. This is the first survey to date on HBO2 practice, and its results provide worldwide international input from an appropriate survey audience to ensure that it reflects current HBO2 practice.
Regarding the usage of different pressures, the benefits of higher pressures have been ambivalent. From a cellular perspective, higher pressures are beneficial insofar as their ability to increase the proliferation of epithelial cells, endothelial cells, and fibroblasts, their power to suppress neutrophil adhesion, and increase angiogenesis and stem cell regeneration, especially above 2.4 ATA. However, similar positive outcomes are yet to be found in the clinical literature. For instance, Ajayi et. al. (2020) compared two different HBO2 protocols (2.0 ATA for 120 minutes vs. 2.4 ATA for 90 minutes) in treating radiation-induced cystitis to see if there was a difference in both clinical and complication rates. Both protocols had similar clinical outcomes, but the 2.0 ATA group received 5.5 more treatments than the 2.4 ATA group.8 In our study, radiation proctitis/cystitis was the only diagnosis with consensus for both pressure and number of treatments: 2.0 ATA (78.87%) and 40 treatments (57.56%), aligning with one of the Ajayi study’s protocols.
However, it cannot be concluded that it is the most effective protocol, only that these parameters are well-known for the treatment of radiation cystitis/ prostatitis and used by most UHMS members. Similarly, Fife et al. looked at HBO2 in treating diabetic foot ulcers between different treatment protocols. They found no difference in outcomes, aligning with the disagreement reported for this condition among our survey’s respondents. This is also true for treating carbon monoxide poisoning and late radiation tissue injury. As such, while cellular benefits have been seen in previous studies, the lack of undisputable evidence in favor of the clinical benefits of higher pressures accompanied by the risk of oxygen toxicity associated with higher pressures can explain the lack of uniformity among respondents utilizing higher pressure therapies.
Despite the risk of oxygen toxicity and seizure, HBO2 is generally considered a safe procedure with well-known minor adverse effects (AE).9 This is also reflected in the survey results, as the most seen complications by respondents were myopia, barotrauma, and confinement anxiety. These prevalent AEs, fortunately, have simple treatments and, at most, minor invasive procedures such as myringotomy to treat barotrauma10 These complications rarely lead to a need to terminate HBO2. Also, as none of these AEs are related to pressure utilized, they should not be utilized in discussing which therapeutic pressure to utilize. In contrast, AEs that are mitigated by pressure utilized and can be more serious, such as oxygen toxicity and hypoglycemia, were not commonly reported. Future prospective studies should focus on which pressures the risk of these complications limit pressure increase.
Despite lacking universal protocol for HBO2, most respondents rated their satisfaction with HBO2 outcomes as either “satisfied” or “extremely satisfied.” Like previous studies that compared different HBO2 protocols, the results yielded that multiple protocols were equally subjectively satisfactory according to providers. 3,4 However, as this study did not evaluate objective outcomes, the effectiveness of therapeutic modalities could not be investigated. Thus, a more comprehensive study can be contemplated to analyze possible correlations between disease, pressure usage, complication rates, and satisfaction.11Similarly, while the present study focused on providers, it is important to acknowledge that treatment outcomes can differ according to patients’ experiences and, as such, future studies should focus on patients’ satisfaction following treatment.
As HBO2 gains traction worldwide, attention turns to its availability. While each case most likely differs for a specific patient, cost-effectiveness also plays a role in selecting an HBO2 regimen. While studies have proven that HBO2 adjunctive therapy can be more cost-efficient compared to standard treatment, as noted in a 2008 study regarding the treatment of diabetic foot ulcers, there have yet to be studies that compare and contrast the cost efficacy of different HBO2 regimens.12,13 This is especially true when comparing mono versus multiplace chambers. While it has been noted that monoplace chambers can pose less financial risk due to less need for staffing and decreased cost of installation and maintenance14, multiplace chambers are the most clinically efficient as between 8 to 12 patients can be treated simultaneously.
Similarly, treatment with 2.4ATA may be more efficient as such pressure therapies tend to occur at 90-minute sessions compared to 2.0ATA, which are carried out in 120 minutes. The former protocol allows for increased patient ‘cycling’ and more patients treated per clinical day. A look into the cost-effectiveness of which chamber type and its effect on what pressure is used can also be another study to investigate.
Finally, an important point to note is the lack of heterogeneity of educational backgrounds among respondents: while some mention fulfilling formal training accredited by the UHMS, most reported participating in introductory courses. As HBO2therapy constantly evolves, those not participating in accredited programs or brief 40-hour introductory courses may not be fully equipped or receive the most up-to-date information. Thus, they may base their clinical decision-making on out-of-date trials and guidelines. As such, the authors advocate for education standardization among practitioners involved in hyperbaric care.
As expected, there was no true consensus regarding a regimen for HBO2. Ideally, a flawless protocol would be tailored specifically to each patient’s specific needs, addressing the multiple components that can affect HBO2.
LIMITATIONS
The reliability and validity of the survey were not assessed, but the contribution of more than 200 clinicians who utilize HBO2lends to the validity of the content. This survey was only available in the English language, and thus, members of the UHMS whose primary language was not English could not participate. The translation of surveys to commonly used languages can be considered in the future. It is noted that the satisfactory gauge is subjective, as terms such as “extremely satisfied” versus “satisfied” were not defined and based on the respondents' definitions. Furthermore, it was not specified to a specific pressure. For instance- if a respondent had used multiple pressures to treat a diagnosis, the satisfactory rating was not separated for each pressure.
CONCLUSION
There is currently little consensus regarding the best treatment pressure for conditions treated with HBO2. Decisions on HBO2should be based on multifactorial factors, including disease severity, patient and provider preferences, and individual patient socioeconomic variables. As adverse effects appear non-negligible, future prospective studies must be conducted to compare the effectiveness of higher and lower-pressure modalities, assessing the risks and benefits associated with each. In addition, while providers' satisfaction with treatment outcomes was largely positive, future studies should also aim to assess patient satisfaction.
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