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The growth of undersea and hyperbaric medicine in the 1960s led to the establishment of the Undersea Medical Society (UMS) in 1967, in which a major research and education role was dedicated towards managing diving-related emergencies, i.e., decompression sickness, with hyperbaric oxygen (HBO2) therapy. HBO2 therapy is defined as an intervention in which an individual breathes 100% oxygen intermittently while inside a hyperbaric chamber that is pressurized to greater than sea level pressure (1 atmosphere absolute, or ATA). From these early days there has been continuous growth in HBO2 therapy and it is now used for a variety of medical conditions. Today, the UMS is now the Undersea & Hyperbaric Medical Society (UHMS), and they provide evidence-based recommendations for HBO2 therapy indications – see Table 1.

Table 1. Indications for HBO2 Therapy

With the rapid growth of non-emergent HBO2 facilities for non-healing wounds, what was not anticipated was the decline of available HBO2 facilities for emergencies. Our concern is that many recreational scuba divers may be unaware of this growing problem and assume incorrectly that local hyperbaric chambers will provide emergent HBO2 for diving-related illnesses. Thus, our intent is to bring attention to the loss of 24/7 emergent HBO2 facilities in the United States, and to bring awareness of the action steps recently taken in effort to reverse this trend.


Scuba divers are trained to know that the primary treatment for decompression sickness and gas embolism is recompression with hyperbaric oxygen. The Divers Alert Network (DAN) presents an excellent overview of several different types of hyperbaric chambers. There are three primary classifications for chambers:

Class A - multiplace chambers are large enough to accommodate multiple patients inside the chamber.
Class B - monoplace chambers treat one patient at a time; they are the most common in the U.S.
Class C - animal chambers are not used to treat people.
Pre-dive trip planning should include locating the nearest chamber that will provide emergency HBO2 treatment in case of a diving emergency. Additional overview of scuba diving safety, prevention and hyperbaric chambers safety and credentialing can be reviewed at DAN. The UHMS maintains a list of accredited clinical HBO2 facilities; DAN maintains a list of hyperbaric treatment facilities that will accept emergency HBO2 patients. Previously, DAN reported that the number of HBO2 facilities available to treat diving-related emergencies 24 hours per day, 7 days a week (24/7) dropped from 37% in 2004 to only 7% in 2016, and this downward trend continues today. Recently, an Open Letter to the UHMS journal editors stated that each year in the United States there are approximately 70,000 patients for whom emergency HBO2 treatment is indicated – see Table 2. However, fewer than 10% of the approximately 1,300 U.S. hyperbaric facilities will accept emergency HBO2 patients. The number of hyperbaric treatment facilities in the U.S. that offer emergent HBO2 on an intermittent basis is 99 according to the list provided by DAN. The number of hyperbaric treatment facilities in the U.S. that offer full-time access to emergent HBO2 therapy is 78 as of June 2020, with several treatment facilities having just dropped their 24/7 emergent HBO2 availability (Personal communication: Dr. Jim Chimiak – 29 May 2020; personal communication Mr. Dick Clarke – 19 June 2020).

Table 2. Seven indications for emergent HBO2 care. Source: "Access to emergent hyperbaric oxygen (HBO2)

therapy: an urgent problem in health care delivery in the United States," UHMS 2020.

There are approximately three million recreational scuba divers in the U.S. In the unlikely event that they suffer a diving-related injury, they trust that the U.S. medical system will provide state-of-the-art care for their injuries. However, the steadily decreasing number of hyperbaric treatment facilities in the U.S. willing to treat them emergently for decompression sickness or arterial gas embolism often places them at much greater risk than they realize. Most patients who need emergent HBO2 therapy are not in an area with a 24/7 emergency hyperbaric facility. Despite the urgent need for diving-related recompression therapy, today most hyperbaric facilities will decline to accept emergent patients. If a patient eventually receives HBO2 treatment, it is only after a significant delay (see case report) due to the need to be transported a hyperbaric treatment facility several hundred miles away, and it is quite possible they may never receive the needed HBO2 therapy.

Two decades ago, almost all hyperbaric treatment facilities provided emergent HBO2 therapy to patients when needed. In 2017, however, a commentary by Dick Clarke, UHMS stated that the growing prevalence of provision of HBO2 therapy as a venture capital owned, for-profit enterprise has changed this landscape dramatically. There are a number of other considerations that may factor into organizations’ decisions not to make their hyperbaric treatment facilities available to provide emergent HBO2 therapy – see Table 3.

Table 3. Rationale for a lack of emergent HBO2 chambers.

Call To Action

So, what has been done to date about this situation? The UHMS has partnered with the American College of Surgeons, the American College of Emergency Physicians, DAN, the Academy of Underwater Arts and Sciences, and eight other organizations. A letter describing this significant deficiency in U.S. health care was sent to President Trump in 2020, four cabinet secretaries, and elected representatives both in Congress and at the state level to bring this issue to their attention.

This letter also included a White Paper, “Access to emergent hyperbaric oxygen (HBO2) therapy: an urgent problem in health care delivery in the United States.” The White Paper enumerated the following steps that could be taken to incentivize hyperbaric treatment facilities to offer emergent care:

  • Direct federal or state grants to hyperbaric treatment facilities that offer emergent HBO2;
  • Indemnification from legal liability for hyperbaric treatment facilities and medical providers who provide emergent HBO2 to divers and other patients who require it;
  • Recognition of the public service performed by the hyperbaric treatment facilities that offer HBO2 on an emergent basis when indicated;
  • Favorable consideration with respect to Medicare, Medicaid, and private insurance reimbursements to hyperbaric treatment facilities and medical providers that offer HBO2 on an emergent basis when indicated, including carve-outs to inpatient DRG (diagnosis-related group) payments;
  • Incentives for military hyperbaric facilities to provide emergent HBO2 to civilian patients through emphasis on the training benefit to military providers that this accomplishes; third-party reimbursement for emergency HBO2 therapy provided to civilian patients by military hyperbaric facilities; and indemnification of the military facility from lawsuits resulting from this public service activity.

Final Thoughts

It is our strongest desire to find a solution to this problem by bringing awareness along with possible solutions to federal, state, and regional leaders. In this Call to Action, we encourage you to seek out your state and regional leadership and make them aware of this problem by providing the two supporting documents mentioned above, the Open Letter and the White Paper. When the standard of care for emergent HBO2 medical conditions is routinely not being met and places those in need at greater risk for permanent neurological disability and even death, it is time for action. As recommended for any scuba diving trip, always dive safely to mitigate the risk of diving-related illnesses. Seek out and acquire medical evacuation insurance. The Wilderness Medical Society requires medical evacuation insurance for all their sponsored adventure activities.

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