Help Center

Answers to frequently asked questions,
designed to support clinicians

Learn about Oxygen

Discover why oxygen is critical to wound healing.

How can oxygen therapy help my patient?

Wound perfusion is frequently insufficient in patients with chronic wounds, thereby reducing the wounds capacity to heal.1 Adding supplementary oxygen can help at any phase of wound healing.2

Who can benefit from oxygen therapy?

NATROX® O2 is intended for wounds healing by secondary intention that would benefit from topical oxygen therapy including:

    • Diabetic foot ulcers
    • Leg ulcers (venous, arterial, mixed)
    • Pressure injuries
    • Surgical and traumatic wounds

Can be used under compression therapy.

Clinical signs of wound hypoxia

Signs of chronic or prolonged wound hypoxia to look for include: a presence devitalized tissue, unhealthy granulation tissue, frequent wound infections, and a failure to heal.

What to Expect

Understand what NATROX® O2 delivers so you can set the right expectations for your patients.

How long treatment lasts…

On average, treatment is typically 8-12 weeks, but this can vary from patient to patient. Generally, there are stages of healing that help to indicate the wound is on a healing trajectory:

During the first 2 weeks…

It’s not abnormal for a wound to increase in size initially.

Explanation: Experience indicates it can take up to 6 weeks before wound reduction is evident. However, you will often see improvements in wound pain, tissue color of the wound bed and wound edge before the wound size reduces.

Pain reduction often reported by patients…

Nerve endings are very sensitive to reduced levels of oxygen. Therefore, increasing oxygen levels can significantly help with pain relief.

Explanation: Applying NATROX® O2 reverses wound hypoxia, so within a few days nerve endings return to normal. Furthermore, a prolonged inflammatory response also stimulates nerve pain fibers. As stimulus causing the inflammation is resolved by NATROX® O2 therapy, there is a further reduction in pain.

We read that NATROX® O₂ Therapy could increase wound size during the first weeks. Why is that?

Yes, especially at the beginning of treatment (in the first 2 weeks), it’s not abnormal for a wound to increase in size initially. Experience indicates it can take up to 6 weeks before wound reduction is evident. However, you will often see improvements before the wound size reduces: reduced pain, and improved tissue colour of the wound bed and around the wound edges.

Explanation: Because oxygen is helping kickstart the healing process, part of healing is removing non-viable tissue. So, when sloughy tissue is removed, the wound looks bigger. However, this was not healthy tissue to start with and would have needed to be debrided, etc. After the non-viable tissue is gone, then you will begin to see healthy tissue forming and improved tissue granulation.

PRO LEVEL EXPLANATION: Wounds need to clear damaged tissue first in order to then replace it with new tissue. This is normally the role of the inflammatory process; but in these patients, the inflammatory process is impaired. The addition of supplemental topical oxygen helps provide energy to the cells to help the natural healing process. The increase in exudate and wound size are the first signs that the wound environment is changing. Once this is complete, the wound will start to produce healthy granulation tissue and the wound will progress to healing.

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Hints and tips

Practical information from real-world experience.

Are there any specific dressings I should use?

No. The choice of dressing is down to clinical preference. However, semi-occlusive dressings have enhanced properties for retaining oxygen levels.

Explanation: As long as the NATROX® ODS is in direct contact with the wound bed, most dressings can be used. Exudate levels need to be considered, as often these will increase, so superabsorbent dressings may be useful. You can use both a primary and secondary dressing (e.g. hydrofiber/gelling fiber and adhesive foam) with NATROX® O2 if necessary.

Are there wound care products to avoid?

  • Topical ointments/creams (L-Mesitran ointment, Iodosorb, Flamazine)
  • Topical gels, including hydrogels (e.g. Intrasite, metrogel)
  • Topical debridement agents (e.g. Collagenase Santyl, Octenilin Wound Gel)

If the wound increases in size…

It’s not unusual for the wound to increase in size initially. If there are no clinical signs of infection, continue with NATROX® O2 therapy.

Explanation: Many chronic wounds have non-viable tissue in the wound. NATROX® O2 therapy can stimulate the body’s natural scavengers (neutrophils and macrophages), which helps debride dead tissue. This process then reveals healthy underlying tissue from which wound healing can start. However, the process can increase wound size initially.

Once the wound starts to improve…

We would advise you to continue NATROX® O2 therapy until complete wound closure is achieved.

Explanation: If the wound only started to progress once NATROX® O2 was applied, then the wound was likely to have been hypoxic. Stopping NATROX® O2 therapy will reduce oxygen levels again and healing might stall, or the wound could even deteriorate.

Shortly after wound closure…

After a patient’s wound has just closed, we do not advise immediately stopping NATROX® O2 therapy. Some clinical teams have reported using it for a couple of weeks after initial epithelial coverage.

Explanation: Newly formed skin is very fragile and prone to further breakdown. Oxygen delivered through the NATROX® ODS will still diffuse through the newly formed epithelium into the underlying supporting tissues. Continued use of NATROX® O2 will continue to aid the rebuilding of collagen in the tissue, potentially impacting on recurrence rates.

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Advanced Usage

Optimizing the impact of NATROX® O₂ therapy.

Managing large/deep wounds

There is no restriction on the maximum size or depth of a wound you can treat, as long as the NATROX® ODS is in contact with the wound bed.

Explanation: If the wound is very narrow and deep, it might not be possible to achieve optimum placement of the NATROX® ODS, due to the size of the product. If this is the case, it might be beneficial to consider another treatment option at least initially.

Can I apply it over slough or necrotic tissue?

We always advise to get wound as clean as possible before applying NATROX® O2.

Explanation:  It is possible to apply NATROX® O2 if there is slough or necrosis present. However, efficacy from a healing perspective will be impacted because slough or necrosis impairs oxygen diffusion, depending on the amount present. Higher oxygen levels increase neutrophil and macrophage activity and may help speed up the body’s natural debridement process.

Wounds that have been present for years…

Very chronic wounds, even those which have been present for years, can still respond and benefit from NATROX® O2 therapy.

Explanation: The longer a wound has been present, the longer it can take to kickstart the healing process and see a reduction in wound size. For wounds over 1 year old, an improvement of 20% in 8 weeks can be considered successful.

Can I use it on patients with multiple wounds?

Although the location and size of the wounds will dictate the best application method.

Explanation: There are 3 ways to manage multiple wounds:

  • Small close-together wounds: manage with 1 OG and 1 ODS covered with 1 secondary dressing.
  • Small wounds in close proximity: manage with 1 OG a Y connector, or 3-way tap and 2 ODS’.
  • Large wounds further apart: manage with 2 separate systems.

Can I use it on patients taking antibiotics?

You can start NATROX® therapy; however, if the wound is still showing signs of clinical infection, then wait until it has settled.

Explanation: NATROX® O2 therapy may be useful in clearing anaerobic bacteria from a wound because high levels of oxygen are toxic to them. However, it is important to remember that NATROX® O2 is not a substitute for antibiotic therapy.

Can I use it with NPWT?

There is no evidence to date that supports combining both therapies.

Explanation: The oxygen produced by the NATROX® Oxygen Generator (OG) will be removed from the wound bed when negative pressure therapy is applied. Large complex wounds might benefit initially from the use of NPWT before changing to NATROX® O2 to stimulate better collagen formation and enhance epithelial closure.

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All About the Device

Learn more about the system to better support your patients.

How the device generates oxygen

The cell inside the NATROX® OG reacts with moisture in the air, splitting it into its component parts, one of which oxygen.

Explanation: Oxygen is generated though water electrolysis. NATROX® O2 uses energy to separate water into oxygen and hydrogen. Only the oxygen passes though the membrane within its cell, leaving the hydrogen to reattach to air, thus producing more water and restarting the process again. It’s worth remembering that because this oxygen is produced chemically, it’s completely sterile.

Pro tips on tubing placement

When positioning the tube, patients should avoid sitting, standing, or resting on it during the day. For example, avoid placing the tubing behind the thigh. Also, it’s best to avoid placing the tube where it may create discomfort or prolonged pressure on the skin.

How to know the device is charged

A yellow light flashes on the battery while it’s charging. The light stays solid after the battery is fully charged.

PRO TIPS: We recommend patients always keep one battery charging while the second battery is in use. It’s best to advise patients to create a set time each day or night to swap the battery, so they develop a pattern of charging and using.

How long the battery lasts

A fully charged battery lasts up to 24-hours.

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All About the ODS

Pro tips on how to best use the NATROX® Oxygen Delivery System.

How often should I change the ODS?

Change the ODS whenever you change the secondary dressing. However, the ODS needs to be changed at least once a week.

Can I cut the NATROX® ODS to smaller size?

If the wound you’re treating is smaller than the ODS, it’s best not to cut it down to a smaller size. The ODS is designed to diffuse oxygen evenly across the whole wound bed.

Explanation: Cutting the ODS results in oxygen diffusing from the cut edge, not the under surface of the ODS. Therefore, you will not optimize oxygen diffusion across the whole wound. Instead, choose an ODS that best covers the wound to expose the majority of the wound bed to oxygen.

Can I place it over intact skin?

Yes, it is safe to apply the NATROX® ODS on healthy peri-wound skin.

Explanation: Because the ODS only diffuses humidified oxygen, there are no issues with it overlapping onto intact healthy skin.

Can I place it over unhealthy peri-wound skin?

A barrier cream should be applied to unhealthy peri-wound skin to protect it from further damage before placing the NATROX® ODS over it.

Explanation: NATROX® O2 is designed to kickstart wound healing, so exudate levels can increase initially. This should reduce over time. However, it might be necessary to use a superabsorbent dressing to help manage exudate and reduce the risk of maceration.

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Expand Reference List

[1] Armstrong DG, Cohen K, Courric S et al (2011) Diabetic foot ulcers and vascular insufficiency: our population has changed but our methods have not. J Diabetes Sci Technol 5(6): 1591-5

[2] Consensus round table meeting: Topical oxygen therapy for healing complex wounds. London: Wounds International, 2018. Available to download from: