Emergency Oxygen First Aid Course for Divers

Jeffrey J. Bertsch, CHT, DMT-A, Hyperbaric Program Director, Mariners Hospital
Dan Orr, MS, VP Operations, Divers Alert Network

Over the years in the diving community, we’ve read and heard about the importance of providing emergency oxygen to an injured scuba diver prior to entering the EMS system. According to recreational diving data collected by the Divers Alert Network (DAN), a non-profit diving medical and safety organization affiliated with Duke University Medical Center, actual oxygen use in diving emergencies declined for a short time from 1987 to 1990.

In 1991, however, when DAN introduced its four-hour modular oxygen first aid program to the diving and medical communities, accident statistics revealed for the first time an increase in emergency oxygen first aid. Since the introduction of the DAN program, over 30,000 DAN Oxygen Providers and 3,000 Oxygen Instructors have been trained in over 30 different countries.

Oxygen first aid is not just another trend in the diving community. The beneficial effects of breathing oxygen — especially when decompression illness (decompression sickness and arterial gas embolism) is suspected — has been well known for over 100 years. Here’s a brief look at the history of oxygen’s association with diving.

Oxygen: An Historical Perspective

In 1878, French physiologist Paul Bert showed conclusively in studies with compressed air divers and caisson workers who worked in diving bells that decompression sickness was caused by inert gas bubbles. Bert further demonstrated that these symptoms improved after inhaling surface oxygen. In one of his experiments on animals he noted: “The favorable action of oxygen was . . . evident; after several inhalations (of oxygen) the distressing symptoms disappeared.”

In a later entry, Bert attempted to explain why oxygen worked. “I thought that if the subject were caused to breathe a gas containing no nitrogen — pure oxygen for example — the diffusion would take place much more rapidly and perhaps would even be rapid enough to cause all the gas (nitrogen) to disappear from the blood.”

This is indeed why oxygen is so useful in treating decompression illness. Bert was the first to propose the concept of oxygen recompression therapy, though the actual practice wasn’t implemented until many years later. In the early 1960s the use of oxygen in recompression treatment for diving accidents increased, but with recreational diving in its infancy, oxygen first aid at the scene of an accident was, for the most part, an unheard-of concept.

It wasn’t until 1976, when noted Australian physician and diver Dr. Carl Edmonds recommended 100 percent oxygen while transporting an injured diver, that oxygen began to emerge as the standard of care for diving injuries.

The movement continued to gain momentum. In 1982, Drs. Jefferson Davis and D.H. Elliott, pioneers in the field of diving and hyperbaric medicine, recognized the value of 100 percent oxygen. Its application, they noted, aided “inert gas elimination from tissues and existing bubbles” in cases of suspected decompression sickness while providing oxygen to hypoxic (oxygen-deficient) tissues.

As oxygen therapy grew in use and recognition, the people who administered oxygen found greater efficiency in some types of masks they were using. Diving medicine expert Dr. Eric P. Kindwall, speaking on the emergency treatment of arterial gas embolism in 1984, noted that oxygen is most effective when administered through a tightly fitting or nasal mask. “The object,” he said, “is to denitrogenate the patient by excluding nitrogen from the lungs.” It became apparent that mask selection had a significant impact upon the fraction of inspired oxygen (FIO2). Masks and delivery techniques which limited dilution from ambient air resulted in a higher FIO2 and ultimately better treatment for the injury.

Attendees at the 41st Undersea and Hyperbaric Medical Society Workshop on Diving Accident Management in 1990 recommended that high concentrations of oxygen (FIO2's approaching 1.0) be continued from the time the accident is recognized until the injured diver reaches a medical facility for definitive diagnosis and treatment. They also suggested that dive instructors and divemasters be trained to administer oxygen. This recommendation laid the cornerstone for the development and implementation of DAN’s Oxygen First Aid Program a year later.

The Value of Oxygen

In 1922 English physiologist John Scott Haldane, an early pioneer in decompression theory, demonstrated that a nitrogen bubble formed in the body as a result of decompression can be absorbed (resolved) when its nitrogen partial pressure is greater than nitrogen tension in the arterial blood. This occurs as a direct consequence of the laws of diffusion. Gases move from areas of higher concentration (partial pressure) to areas of lower concentration (partial pressure). The time frame for this to occur, while breathing air (because it contains nearly 80 percent nitrogen), may require several hours or days, depending of the size of the bubble. Eliminating or significantly reducing the nitrogen in the injured diver's breathing medium will significantly increase nitrogen elimination by diffusion. The driving force for the elimination of nitrogen is, therefore, the partial pressure difference between dissolved nitrogen and that in the patient's breathing medium.

As the diver breathes high partial pressures of nitrogen during an air dive, the diver's body tissues absorb an ever-increasing amount of nitrogen. The longer and deeper the dive, the greater the quantity of dissolved nitrogen in the diver's blood and other tissues. As the diver ascends, the nitrogen partial pressure in the breathing medium drops and the difference between the dissolved partial pressure and that in the breathing medium increases thus causing the elimination of nitrogen. At the surface following the dive, the nitrogen partial pressure in the tissues and in the venous blood is greater than the nitrogen partial pressure in the ambient air. If this partial pressure differential is great enough, nitrogen in the diver's blood and other tissues cannot remain in a dissolved state and the result in the formation of nitrogen bubbles. Asymptomatic 'silent' bubbles, may not create any observable signs or symptoms whereas symptomatic bubbles are known as 'the bends' or decompression sickness (DCS). Signs and symptoms that do appear may range from a very vague 'general ill feeling' to much more severe joint pain and/or paralysis.

When an injured diver suffering from DCS breathes 100 percent inspired oxygen, the result is a decrease in nitrogen partial pressure in the blood and other tissues surrounding the blood vessels and bubbles. The resulting diffusion gradient may help to reduce bubble size by diffusion. The greater the gradient, the more rapidly nitrogen will be eliminated from existing bubbles thus reducing their size and possibly resolving existing signs and symptoms. A similar situation exists with nitrogen still dissolved in the tissues. When breathing high concentrations of inspired oxygen, nitrogen diffuses out of the tissues into the blood at a rate proportional to the concentration differences and is then carried to the lungs, where it is eliminated through respiration. Rapid elimination of nitrogen from the tissues reduces the likelihood that dissolved nitrogen from the tissues will diffuse into existing bubbles increasing their size or that the nitrogen will precipitate the formation of additional bubbles thus exacerbating the injured diver's condition.

Therefore, along with reduction in bubble size and improvement in circulation, emergency oxygen first aid may reduce tissue damage from hypoxia and increase the likelihood of resolution of symptoms resulting in a positive outcome from recompression therapy.

The Problem and a Solution

DAN’s dive accident data over the years has revealed trends in the use of oxygen. In 1987 less than 37 percent of those injured in dive accidents received pre-hospital emergency oxygen. Of those, only a few received the recommended 100 percent inspired oxygen. The years 1987 to 1990 show a decline in oxygen first aid, falling from 37 percent to less then 34 percent.

What were the reasons for this decline? Although speculative, there seems to have been several factors at work. Most dive medicine experts attribute the decline to misinformation or lack of information about the use of oxygen.

First, many divers thought then — and may continue to believe — that providing emergency oxygen may be illegal. There are, in fact, very few laws that pertain the use of oxygen for emergency purposes by trained providers in a pre-EMS situation. State laws, if they address the issue at all, simply state that individuals providing emergency oxygen must have training and do not clearly define "training."

Some states do indicate, however, that non-trained individuals may not be provided immunity under the Good Samaritan Act. Each of the United States’ 50 states and Washington, D.C., has a Good Samaritan statute, all of which have common characteristics despite some differences in details. These statutes provide some protection for volunteers who choose to come to the aid of another individual, provided they exercise reasonable care. The vast majority of Good Samaritan laws in the US provide immunity unless the rescuer acts with gross negligence or recklessness.

Providing emergency oxygen is the recognized standard of care for anyone suspected of oxygen deficiency. The 1992 Journal of the American Medical Association CPR Guidelines state that a rescuer shouldn’t withhold oxygen out of fear of suppressing respiration if hypoxemia (blood oxygen deficiency) is suspected.

Second, until a few years ago, oxygen equipment designed to provide 100 percent inhaled oxygen was not readily available to the diving community at an affordable price. DAN, with the help of several individuals and organizations, developed reasonably priced emergency oxygen units designed for divers to use in diving injuries.

DAN Physicians Drs. Yancey Mebane and Arthur Dick in a 1985 Alert Diver article emphasized that oxygen delivery equipment could be easily used by divers, stating, “The equipment necessary to deliver oxygen in this manner is very similar in principle to scuba equipment.” It’s true. Since that time DAN has been selling — as a community service — affordable and easy to use emergency oxygen units. DAN currently has five variations of affordable emergency oxygen units.

Third, training in emergency oxygen first aid was not readily available to the general diving public until recently. Again, DAN, with the help of dedicated individuals and organizations, developed a four-hour modular oxygen program that, when implemented, would provide training to all divers of any certification level, in the required entry level skills of providing the recommended 100 percent inspired oxygen.

DAN's emergency oxygen first aid training provides divers with a better understanding of diving injury recognition, effective methods in providing emergency oxygen, and will likely introduce the injured diver into the local emergency medical system and definitive medical care more rapidly. This in turn reduces the delay to treatment and the likelihood of long-term complications. An added value from this training is continuing education credits. Some programs, such as that offered by DAN, provide EMT's with 4.0 hours of continuing education credit through the National Association of Emergency Medical Technicians (NAEMT).

Finally, a problem not directly related to oxygen first aid but still a formidable one: the delay from symptom recognition to recompression treatment. This delay currently averages about 18-24 hours, well beyond the estimated window of opportunity for effective dive accident treatment and symptom resolution. Like any injury, delays in treatment exacerbate the condition and reduce the likelihood of a successful outcome.

The Role of the EMS

It is extremely important that emergency medical services groups be prepared to respond to diving injuries. It is not out of the realm of possibility to be presented with a patient showing symptoms of a diving injury even though there is no known dive sites in the vicinity. Divers commonly drive or fly long distances to and from remote dive locations. Since signs and symptoms may not be apparent for some time after the dive, it is conceivable that an injured diver may enter into the local EMS system literally hundreds or possibly thousands of miles from the nearest known dive site. Therefore, it is incumbent upon all EMS personnel to have some knowledge of diving injuries no matter how remote the possibility. In order to provide this valuable information to EMS units, DAN has produced a 30-minute video entitled "Dive Accident Management: Guidelines for EMS," detailing recognition and management of diving injuries by EMS personnel. This valuable tool is available directly from DAN.

DAN's Goal

Over the years, DAN has received numerous reports from divers who have benefited from oxygen first aid training. Many injured divers the world over owe their well-being to the DAN Oxygen Provider who put their oxygen first aid training to good use.

DAN’s ultimate goal in the oxygen program is a coordinated interaction of the diving and EMS communities so that all diving injuries will be recognized immediately and the injured diver will move swiftly and efficiently into the EMS system. This will increase the likelihood of a successful resolution of symptoms and decrease the possibility of lasting, debilitating injury.

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