Key points
- Given the similarities between ME/CFS, fibromyalgia and long COVID, it is useful to compare the effects of hyperbaric oxygen therapy (HBOT) on each of these conditions.
- Research about the effects of HBOT on ME/CFS is limited and has produced mixed results.
- Several small-scale studies involving patients with fibromyalgia have demonstrated significant improvements in symptoms – including fatigue, cognitive difficulties, sleep dysfunction and pain – following HBOT.
- In individuals with long COVID, initial research findings indicate that HBOT can lead to significant improvements in symptoms such as fatigue, cognitive difficulties, sleep dysfunction and pain. However, more research is needed to corroborate these findings.
- Improving methodology and conducting a long-term follow-up would increase the reliability of results, providing greater certainty about the effects of this intervention for patients with ME/CFS, fibromyalgia and long COVID.
What is hyperbaric oxygen therapy?
HBOT is a medical treatment in which patients breathe in pure oxygen whilst inside a chamber with a higher-than-normal air pressure. The increased pressure pushes more oxygen into the lungs and then into the bloodstream, to be delivered to damaged or oxygen-deprived tissues to enhance healing.
HBOT has an established use in treating a range of medical conditions, from diabetic foot ulcers to carbon monoxide poisoning. Whilst not conclusive, there are promising signs that HBOT could be a useful intervention in fibromyalgia and long COVID, but more research needs to be done to establish whether HBOT could be a potential treatment for ME/CFS. It is worth noting that HBOT is not a NICE-recommended treatment for any of these illnesses.
Why use HBOT for these conditions?
ME/CFS, fibromyalgia and long COVID have overlapping symptoms, and potentially overlapping underlying disease mechanisms. One proposed theory is that impaired oxygen delivery to body tissues contributes to symptoms such as fatigue, cognitive difficulties and pain. Therefore, researching the potential benefits of HBOT in enhancing oxygen delivery and reducing the symptoms of these debilitating conditions seems to be a rational approach. Given their shared features, exploring the effects of this intervention on any of these conditions may offer valuable insights for the others.
HBOT and ME/CFS
There is no effective treatment for ME/CFS – a condition characterised by debilitating fatigue, post-exertional malaise, cognitive dysfunction and sleep disturbances, amongst many other symptoms. However, could HBOT be helpful? We simply do not know yet. The effect of HBOT on patients with ME/CFS has only been explored in two noteworthy studies, both of which were small-scale and yielded different results.
The first study was conducted in 2003 and involved 29 patients who received HBOT for one week and were followed up after one month. All patients fulfilled the Fukuda criteria for CFS, however there were two separate patient groups: those with mycoplasma infection (a bacterial infection) and those without. The researchers intended to find out if HBOT could improve symptoms in patients with mycoplasma infection, as evaluated by patient questionnaires measuring several domains including fatigue, pain and physical functioning (ability to carry out activities of daily living). However, as no significant differences in any domains were noted in either group following HBOT, we can extrapolate that overall this study did not demonstrate HBOT to be an effective treatment for ME/CFS.
The second study was conducted in 2013 with 16 patients, also fulfilling the Fukuda criteria, who received HBOT for three weeks. Patients were evaluated with questionnaires to determine the severity of fatigue and the impact of fatigue on quality of life. Following HBOT, patients reported significant improvements across all domains. Unfortunately, there was no follow-up to assess if these effects continued.
It is currently unclear how many sessions of HBOT are needed to determine its effects, so it is possible that the duration of the intervention in the first study was insufficient to observe any changes. Overall, we cannot draw firm conclusions as both studies had a small sample size and lacked a control/comparison group who did not receive HBOT.
Ideally, the next study exploring the effects of HBOT on ME/CFS should be a randomised controlled trial (RCT) which is the most reliable method for studying interventions. However, RCTs tend to be more costly and time-consuming compared with other study designs.
HBOT and fibromyalgia
There is considerable symptom overlap between ME/CFS and fibromyalgia, including fatigue, cognitive difficulties, sleep dysfunction and pain. However, pain is a core feature of fibromyalgia rather than an additional feature as in ME/CFS. In terms of research related to HBOT, there are comparatively more studies exploring its effects on fibromyalgia than on ME/CFS.
In January 2023, a comprehensive review and analysis of nine studies investigating the use of HBOT as a treatment for fibromyalgia was published, and found that HBOT may significantly improve the aforementioned symptoms. Three of the studies also demonstrated a reduction in the number of ‘tender points’, which are painful areas of the body that are specific to fibromyalgia. However, the authors noted major limitations across the studies, including small sample sizes and a lack of follow-up. There were only three RCTs which, as previously mentioned, are a gold standard for assessing the effects of interventions. In two of the RCTs, the control group did not receive a sham intervention (‘faked’ intervention designed to mimic the real thing), which would have helped ensure that any observed benefits of the actual intervention were not due to the placebo effect.
Following this review, another RCT was published which involved 64 patients with fibromyalgia (following traumatic brain injury) receiving HBOT for three months. After the intervention there were significant improvements reported in several domains, including fatigue, pain and physical functioning. However, this study also did not have a sham control group – instead, the comparison group followed a medication protocol.
HBOT and long COVID
Whilst long COVID is associated with more than 200 symptoms, it shares similarities with ME/CFS in that fatigue, post-exertional malaise and cognitive impairment are amongst the most reported features. Another frequently reported feature of long COVID is persistent breathlessness – a symptom which further encourages a deeper look into the use of oxygen therapy as a treatment. Numerous news articles have cited HBOT as a promising therapy for long COVID, largely based on the results of the only completed and peer-reviewed RCT to date, the findings of which were published in July 2022.
In the trial, 73 patients with long COVID were randomly assigned to receive either HBOT or a sham intervention (‘fake’ HBOT) for two months. To minimise bias, the study was double-blinded, meaning neither researcher nor participant knew which intervention was given. Following HBOT, a significant improvement was reported across several domains, including fatigue, cognition, sleep and pain.
According to the researchers, the improvements in clinical outcomes were associated with changes on brain MRI (advanced brain imaging), such as increased blood flow and remodelling of specific brain structures. Whilst this study had a larger sample size and seemingly more robust methodology than current studies on HBOT for ME/CFS or fibromyalgia, the authors acknowledge the need for even larger studies to identify which patients could benefit most from HBOT, and that long-term follow-up results are not yet available.
Prior to this RCT, there was a retrospective analysis looking at the medical records of 10 patients with long COVID who received HBOT. This analysis indicated that this intervention could potentially benefit patients with long COVID, but the authors recognised the need for RCTs to corroborate their findings. Another RCT is currently ongoing and could further add to our knowledge about the effects of HBOT on long COVID.
Risks of HBOT
Before considering HBOT, it is important to understand that in the UK, it is not currently an established treatment for ME/CFS, fibromyalgia or long COVID, or recommended in NICE guidelines, and it does carry risks.
In the studies mentioned, facilitators monitored participants for adverse events such as middle-ear barotrauma, which is when pressure differences lead to damage of middle-ear structures, potentially resulting in hearing loss and balance issues. It is worth noting that such barotrauma can also occur during air travel or scuba diving. Additionally, HBOT may not be suitable for individuals with medical issues such as certain heart/lung conditions and claustrophobia.
Therefore, it is essential to discuss the potential risks and benefits with a qualified healthcare provider before undergoing HBOT. Additionally, HBOT is expensive (unless subsidised by a charity) and could require multiple sessions to see an effect.
Conclusion
We cannot draw any conclusions about the effectiveness of HBOT in respect to ME/CFS as the research in this area is lacking. Studies on HBOT for fibromyalgia show promising results in reducing symptoms, but the methodology of these studies could be more robust. Whilst the recently completed RCT on the effects of HBOT on long COVID symptoms provides strong evidence of its potential benefits, further studies are needed to confirm these findings.
As these three conditions share similar symptoms and potentially underlying mechanisms, the encouraging research findings for fibromyalgia and long COVID could inspire further research into the effects of HBOT on ME/CFS.
Sources
- Keller BA, et al. Inability of myalgic encephalomyelitis/chronic fatigue syndrome patients to reproduce VO2peak indicates functional impairment. Journal of Translational Medicine, 2014; 12:104. doi.org/10.1186/1479-5876-12-104
- Elvin A, et al. Decreased muscle blood flow in fibromyalgia patients during standardised muscle exercise: a contrast media enhanced colour Doppler study. European Journal of Pain, 2006; 10(2):137–44. doi.org/10.1016/j.ejpain.2005.02.001.
- Evers G, et al. Sustained impairment in cardiopulmonary exercise capacity testing in patients after COVID-19: a single center experience. Canadian Respiratory Journal, 2022; 2022:2466789. doi.org/10.1155/2022/2466789
