My understanding is that air breaks are uncommon anymore in the HBO2 community and I understand that there is a greater risk of O2 toxicity @ 2.4 ATA or greater. Is there any documented evidence for the need of air breaks during the hyperbaric treatments?
Thank you for your question. The UHMS HBO2 safety committee can provide information to assist you in answering your question, but the ultimate responsibility for these types of questions rests with the medical director and safety director of your facility.
The SC cannot recommend medical practice. The hyperbaric treatment protocol is the responsibility of the medical director and the safety director.
Air breaks are used in the clinical setting for two primary reasons. The first to reduce oxygen toxicity involving the central nervous system. The second is to reduce oxygen toxicity to the pulmonary system. Due to the complexity of our patients and the underlying disease processes, the patient may present with conditions that could possibly lead to a lower threshold limit for oxygen toxicity (i.e. fever, low blood sugars, medications).
A review conducted in 2003 by Hampson & Atik demonstrated an overall seizure rate of 1 in 3,388 treatments or 0.03% (Hampson & Atik, 2003). In 2011 Banham examined the incidence of oxygen toxicity seizures over 41,273 treatments for 3,737 patients and found the overall rate was 0.06% or 6/10,000 exposures with a higher incident rate in patients treated at increased pressures (0.56% at Navy Treatment Table 6 for dysbarism) (Banham, 2011). Another article reported zero per 10,000 at 2.0 ATA, 15 per 10,000 at 2.4/2.5 ATA and 51 per 10,000 at 2.8 ATA (Heyboer et al. 2014). Patients treated for CO poisoning or decompression illness have an incidence as high as 0.5-2%, presumably due to a combination of CNS injury and higher PO2 (2.8-3 ATA) used for treatment of those conditions (Hampson et. al. 1996; Banham, 2011). A 2016 retrospective chart review of 2334 patients treated at a hyperbaric center in Israel found a seizure incident rate of 0.3% (7 patients); however, they determined “only one patient (0.04%) had a true oxygen toxicity event” (Hadanny et al. 2016).
Major pulmonary oxygen toxicity has not been reported during routine clinical hyperbaric treatment, although there is a theoretical risk in patients who receive oxygen within a short interval after certain chemotherapeutic agents such as bleomycin and mitomycin C.
The rationale for air breaks is based upon a study in which volunteers breathed 100% O2 at 2 ATA for up to 19 hours (Hendricks PL, Hall DA, Hunter WL, Jr., Haley PJ. Extension of pulmonary O2 tolerance in man at 2 ATA by intermittent O2 exposure. J Appl Physiol. 1977;42(4):593-9). Use of 5-minute air breaks after every 20 minutes of 100% O2 delayed the onset of a measurable reduction in vital capacity (-5%) from 6 hours (without air breaks) to 17 hours. We are not aware of any specific studies that look at the influence of air breaks on CNS O2 toxicity. Such a study would be difficult to perform since O2 toxicity is rare.
Air breaks are prescribed in some standard treatment procedures such as USN Treatment Tables for decompression illness. Routine use of air breaks for other hyperbaric treatment algorithms is at the discretion of the treating physician and is often implemented when treatment pressure exceeds 2 ATA. The time or length of the air break can vary from five (5) to ten (10) minutes (up to 15 minutes for treatment protocols used for decompression illness), typically after 100% O2 breathing periods of 20-30 minutes.
Banham ND. Oxygen toxicity seizures: 20 years' experience from a single hyperbaric unit. Diving Hyperb Med. 2011;41(4):202-10
Hadanny, A., Meir, O., Bechor, Y., Fishlev, G., Bergan, J., Efrati, Shai. (2016). The safety of hyperbaric oxygen treatment - retrospective analysis in 2,334 patients. Undersea and Hyperbaric Medicine, 43(2): 113-122
Hampson N, Atik D. Central nervous system oxygen toxicity during routine hyperbaric oxygen therapy. Undersea Hyperb Med. 2003;30(2):147-53
Heyboer M, 3rd, Jennings S, Grant WD, Ojevwe C, Byrne J, Wojcik SM. Seizure incidence by treatment pressure in patients undergoing hyperbaric oxygen therapy. Undersea Hyperb Med. 2014;41(5):379-85
Neither the Undersea and Hyperbaric Medical Society (UHMS) staff nor its members are able to provide medical diagnosis or recommend equipment over the internet. If you have medical concerns about hyperbaric medicine you need to be evaluated by a doctor licensed to practice medicine in your locale, which can provide you professional recommendations for hyperbaric medicine based upon your condition. The responsibility of approving the use of equipment resides with the physician and safety director of the facility. Information provided on this forum is for general educational purposes only. It is not intended to replace the advice of your own health care practitioner and you should not rely upon it as though it were specific medical advice given to you personally.