Bariatric chamber for healing — specifically, higher-capacity hyperbaric oxygen therapy (HBOT) — offers a potential adjunctive treatment pathway for patients with obesity who require pressurised oxygen delivery for wound healing and related complications. Standard hyperbaric chambers are not always suitable for individuals with a larger body habitus, making access to appropriately sized equipment a critical consideration. This article explains how higher-capacity hyperbaric chambers work, their clinical applications in patients with obesity or following bariatric surgery, relevant NICE guidance, safety considerations, and how to access treatment through the NHS.

What Is a Large-Capacity Hyperbaric Chamber and How Does It Work?

A higher-capacity hyperbaric chamber is a pressurised enclosure delivering 100% oxygen at 2.0–2.4 ATA for wound protocols, increasing plasma oxygen to enhance tissue oxygenation, stimulate angiogenesis, and support healing in patients with obesity who cannot use standard chambers.

A large-diameter or higher-capacity hyperbaric chamber is a specially designed pressurised enclosure built to accommodate patients who cannot safely or comfortably use standard hyperbaric oxygen therapy (HBOT) chambers — including those with a higher body weight or larger body habitus. Standard monoplace chambers are typically designed for patients up to a certain weight threshold; higher-capacity models are engineered to support individuals beyond this limit, though exact specifications vary considerably between manufacturers and centres. Patients and referring clinicians should confirm chamber dimensions and weight limits directly with the treating hyperbaric unit before referral.

Hyperbaric oxygen therapy works by delivering 100% pure oxygen to a patient within a chamber pressurised to greater than one atmosphere absolute (ATA) — typically between 1.5 and 3.0 ATA. For chronic wound protocols, pressures of 2.0–2.4 ATA are most commonly used. Under these elevated pressure conditions, oxygen dissolves directly into the blood plasma rather than relying solely on haemoglobin transport. This substantially increases the amount of oxygen delivered to tissues throughout the body, including areas with compromised circulation.

The physiological effects of this oxygen-rich environment include:

• Enhanced tissue oxygenation — particularly beneficial in hypoxic or ischaemic wound beds

• Stimulation of angiogenesis — promoting the formation of new blood vessels

• Antimicrobial activity — high oxygen concentrations are toxic to many anaerobic bacteria

• Reduction of oedema — primarily through vasoconstriction

• Collagen synthesis promotion — supporting wound closure and tissue repair

For patients with obesity, who frequently experience impaired wound healing due to factors such as poor peripheral circulation, diabetes, and increased susceptibility to infection, access to an appropriately sized chamber may be required to enable HBOT to be delivered safely and effectively. Patients and clinicians should contact individual hyperbaric units to confirm suitability and equipment availability.

Clinical Uses of Hyperbaric Oxygen Therapy in Patients with Obesity

HBOT may be considered adjunctively for diabetic foot ulcers, post-surgical wound complications, necrotising fasciitis, compromised grafts, and radiation tissue injury — though most indications are not routinely commissioned and require individual clinical justification.

Hyperbaric oxygen therapy has an established role in the management of several conditions that disproportionately affect individuals with obesity or those who have undergone bariatric surgery. The intersection of metabolic dysfunction, reduced tissue perfusion, and surgical complexity makes this patient group particularly vulnerable to complications that HBOT may help address. It is important to emphasise that HBOT is always adjunctive — it does not replace optimal standard care, including revascularisation, offloading, infection control, and nutritional support.

Clinical indications relevant to this patient group include:

• Diabetic foot ulcers and chronic wounds — Many patients seeking or having undergone bariatric surgery have type 2 diabetes, which significantly impairs wound healing. NICE NG19 (Diabetic foot problems: prevention and management) advises that HBOT should not be offered routinely for diabetic foot problems and should only be considered in the context of a research programme. It is not a standard treatment option outside such settings.

• Post-surgical wound complications — Bariatric procedures such as Roux-en-Y gastric bypass or sleeve gastrectomy can occasionally result in anastomotic leaks, wound dehiscence, or deep surgical site infections. Evidence for HBOT in this context is limited to case reports and small series; it is not a routinely commissioned indication and would require individual clinical consideration and, where applicable, an Individual Funding Request (IFR).

• Necrotising fasciitis — A rare but life-threatening soft tissue infection that can occur post-operatively. HBOT is sometimes used as an adjunct to surgical debridement and antibiotics; however, the evidence base is of low quality and this is not routinely commissioned in England.

• Compromised skin grafts and flaps — Patients undergoing body contouring surgery following significant weight loss may develop graft or flap failure, where HBOT may support tissue viability in selected cases.

• Radiation tissue injury — HBOT is an established treatment for specific radiation-induced tissue damage, such as osteoradionecrosis and radiation cystitis or proctitis, in certain circumstances. Access is subject to commissioning criteria.

Referral to a hyperbaric medicine unit should be made in conjunction with the patient's surgical team, diabetologist, or wound care specialist, ensuring that underlying conditions are being optimally managed alongside any hyperbaric treatment.

Evidence and NICE Guidance on Hyperbaric Therapy for Wound Healing

NICE NG19 states HBOT should not be offered routinely for diabetic foot problems except within a research programme; Cochrane evidence shows some benefit but significant methodological limitations prevent a firm recommendation.

The evidence base for hyperbaric oxygen therapy in wound healing has grown over recent decades, though the quality and consistency of evidence varies across different clinical indications. In the UK, NICE guidance provides an important framework for clinical decision-making.

For diabetic foot ulcers, NICE guideline NG19 (Diabetic foot problems: prevention and management) states clearly: do not offer hyperbaric oxygen therapy to treat diabetic foot problems, except in the context of a research programme. This reflects the current evidence position and should be the starting point for any clinical discussion about HBOT in this indication.

The Cochrane Review on HBOT for chronic wounds (2023) found some evidence of benefit in diabetic foot ulcers in terms of wound healing rates and reduction in major amputation, but the authors highlighted significant methodological limitations in available studies — including small sample sizes, risk of bias, and heterogeneity — meaning firm conclusions cannot be drawn. The review supports the view that further high-quality research is needed before HBOT can be recommended as a routine intervention.

There is no single NICE interventional procedures guidance (IPG) that broadly endorses HBOT for non-healing wounds; clinicians should refer to the specific NICE guidance relevant to the indication in question and check the NICE website for the most current publications.

In practice, clinicians should:

• Assess each patient individually against current NICE criteria and commissioning policies

• Document clinical rationale clearly when referring for HBOT, particularly when submitting an IFR

• Ensure standard wound care is optimised before and during HBOT — HBOT must not delay or replace guideline-recommended standard care

• Enrol patients in research or audit programmes where NICE specifies a research-only context

• Monitor outcomes systematically to contribute to the evolving evidence base

Patients should be informed that HBOT is considered an adjunctive rather than curative therapy, and that for many wound indications it remains outside routine NHS commissioning.

Suitability and Safety Considerations for Higher-Capacity Chambers

Patients must undergo pre-treatment assessment by a hyperbaric physician; absolute contraindications include untreated pneumothorax, and precautions include severe COPD, unstable cardiovascular disease, bleomycin therapy, and uncontrolled seizure disorders.

Patient safety is paramount when considering hyperbaric oxygen therapy, and this is particularly true for patients with obesity, where both the physical dimensions of the chamber and the patient's underlying health profile require careful assessment. Not all hyperbaric units in the UK are equipped with higher-capacity chambers, making pre-referral assessment essential.

Physical and technical considerations include:

• Weight and size capacity — Higher-capacity chambers must be certified to accommodate the patient's weight safely. Clinical teams should confirm chamber specifications directly with the unit before referral, as capacities vary by manufacturer and installation.

• Internal diameter — Adequate space is required not only for patient comfort but also for safe positioning, particularly if the patient has limited mobility or requires monitoring equipment.

• Emergency egress — Protocols must be in place for safe evacuation of patients in the event of an emergency during pressurisation.

• Device compatibility — Insulin pumps, cochlear implants, and certain other implanted or electronic devices may be incompatible with monoplace chambers. Patients should inform the hyperbaric unit of all implanted devices so that unit-specific checks can be carried out.

Medical contraindications and precautions include:

• Untreated pneumothorax — An absolute contraindication to HBOT

• Severe bullous lung disease or significant COPD — Requires careful assessment due to risk of air trapping and oxygen toxicity

• Unstable cardiovascular disease (e.g., decompensated heart failure, recent myocardial infarction) — Must be stabilised prior to treatment

• Uncontrolled seizure disorder — Requires assessment and optimisation before HBOT

• Active upper respiratory tract infection, ear or sinus infection — Treatment should be deferred until resolved, as pressure changes increase the risk of barotrauma

• Untreated fever — Should be investigated and managed before commencing HBOT

• Pregnancy — A relative contraindication in most circumstances; specialist advice should be sought

• Claustrophobia — May be relevant in some chamber designs; patient counselling and, where appropriate, psychological support are important

• Certain medications — Previous or concurrent bleomycin therapy warrants caution due to pulmonary toxicity risk. Some other oncology agents (e.g., recent doxorubicin or cisplatin) may require timing considerations. Disulfiram is also a recognised caution. Patients should inform the hyperbaric unit of all current and recent medications.

Diabetes-specific advice: Patients with diabetes should monitor their capillary blood glucose before and after each session, as HBOT can affect glucose levels and increase the risk of hypoglycaemia. Insulin doses and meal timing should be reviewed and adjusted in consultation with the diabetes care team before commencing treatment.

All patients should undergo a thorough pre-treatment medical assessment conducted by a hyperbaric medicine physician, including review of current medications, respiratory function, cardiovascular status, and any history of ear or sinus problems. Patients are advised to inform their clinical team of all current medications and medical conditions before commencing treatment.

Accessing Higher-Capacity Hyperbaric Treatment on the NHS

NHS HBOT for wound healing is not routinely commissioned; patients typically require an Individual Funding Request, and clinicians should contact the British Hyperbaric Association to identify units with higher-capacity chamber availability.

Access to hyperbaric oxygen therapy on the NHS is not universally available and varies significantly by region and by the four UK nations. HBOT is not commissioned as a routine NHS treatment for most indications, meaning that access typically depends on individual funding requests, specialist referral pathways, or enrolment in clinical trials.

In England, NHS England commissions HBOT for a very limited number of indications through specialised commissioning. Patients and clinicians should refer to the current NHS England Clinical Commissioning Policy or Service Specification for Hyperbaric Oxygen Therapy for the definitive and up-to-date list of commissioned indications, as commissioning policies are subject to revision. Decompression illness and arterial gas embolism are among the most consistently commissioned indications; other conditions may or may not be covered depending on current policy.

Commissioning arrangements differ in Scotland, Wales, and Northern Ireland, where separate health service policies apply. Patients in devolved nations should seek guidance from their local health board or trust.

For wound healing indications — including diabetic foot ulcers and post-surgical complications — NHS funding is generally not routinely available and must be sought through an Individual Funding Request (IFR) process. Clinicians submitting an IFR should provide robust clinical evidence of treatment failure with standard care, a clear rationale for HBOT, and documentation of the patient's overall clinical picture. For indications where NICE specifies a research-only context (such as diabetic foot ulcers), enrolment in an approved research programme may be the most appropriate route.

Higher-capacity HBOT adds an additional layer of complexity, as not all NHS hyperbaric units possess the necessary equipment. Patients and referring clinicians should:

• Contact the British Hyperbaric Association (BHA) for a directory of UK hyperbaric units and their capabilities

• Enquire specifically about higher-capacity chamber availability before referral

• Explore private hyperbaric centres if NHS funding is unavailable, noting that costs can be substantial and that NICE positions on specific indications remain applicable regardless of funding route

Patients are encouraged to discuss all options with their GP or specialist team. If standard wound care is not achieving adequate healing, a referral to a multidisciplinary wound care clinic or vascular surgery team should be the first step, with HBOT considered as part of a broader treatment strategy.

What to Expect During and After Hyperbaric Oxygen Therapy

A typical HBOT course involves 20–40 daily sessions of approximately 90 minutes; common side effects include middle-ear barotrauma and temporary myopia, and patients with diabetes must monitor blood glucose before and after every session.

For patients unfamiliar with hyperbaric oxygen therapy, understanding what the treatment involves can help reduce anxiety and improve adherence. A typical course of HBOT for wound healing consists of 20 to 40 sessions, each lasting approximately 90 minutes, usually delivered once daily on weekdays. The exact number of sessions will be determined by the treating hyperbaric physician based on the clinical indication and treatment response.

During a session, patients can expect the following:

• Preparation — Patients are asked to wear 100% cotton clothing (to reduce fire risk) and to remove any petroleum-based products, jewellery, and electronic devices

• Pressurisation — The chamber gradually pressurises over approximately 10–15 minutes. Patients may notice a sensation of fullness or pressure in the ears, similar to descending in an aircraft. Swallowing, yawning, or using the Valsalva manoeuvre can help equalise ear pressure

• Treatment phase — Patients breathe 100% oxygen through a mask or hood whilst resting comfortably. Some patients read, watch television, or sleep during this time

• Depressurisation — The chamber slowly returns to normal pressure over a similar period

After treatment, most patients experience minimal side effects. The most common adverse effect is middle-ear barotrauma (ear pain or discomfort due to pressure changes), which should be reported to the clinical team promptly. Other effects to report include:

• Ear or sinus pain — May indicate barotrauma; do not ignore

• Visual changes — Temporary myopia (short-sightedness) can occur with prolonged courses but typically resolves after treatment ends. Patients should avoid driving if their vision is blurred following a session and should not drive until their vision has returned to its normal baseline

• Oxygen toxicity symptoms — Including unusual tingling, twitching, or confusion. Oxygen-induced seizures are rare but are a recognised risk; any such symptoms should be reported to the clinical team immediately

• Fatigue — Some patients feel tired after sessions; this is generally mild and transient

Diabetes-specific advice: Patients with diabetes should check their blood glucose before and after each session. Hypoglycaemia can occur during or after treatment. Insulin doses and meal timing should be coordinated with the diabetes care team throughout the HBOT course.

Patients should continue all prescribed medications and wound care regimens throughout their HBOT course. Regular review by the wound care or surgical team should run concurrently with hyperbaric treatment to monitor progress and adjust the overall management plan as needed.

Reporting side effects: If you experience any suspected side effects from hyperbaric oxygen therapy, these can be reported to the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk or via the Yellow Card app. Reporting helps improve the safety information available for all patients.

Frequently Asked Questions