Air Travel, Oxygen and the Diver

There is a recurring question that arises concerning the use of oxygen in divers returning by air after having had treatment for a decompression accident. Dr. David DuBois has written asking about the appropriate management of the returning diver continuing to need oxygen after maximum recompression treatment but with residual symptoms. He asks, “Is there a reason that commercial airlines don’t allow use of oxygen during flights? In particular, I’m interested in cases of stable, alert, ambulatory, decompression illness patients who have had initial treatment are returning to the US.”

“It may be the same issue that operates with carrying your own scuba tank. Over the years this has been a major problem. Many airlines required that you remove the valve from the tank so that it was in two parts. I have never understood their logic”, says Glen Egstrom, PhD. “The differential pressure between the cabin and the tank would clearly not increase to the point that it would rupture the burst disc and even if it did the small volume of escaped gas from a tank would have a minimal effect on cabin pressure. A stabilized tank of compressed Oxygen should provide far more benefit than risk.”

In general, airlines do allow oxygen to be used but require considerable forethought and planning. Arrangements must be made in advance and most airlines require a doctor’s letter. The FAA requires a physician’s statement of oxygen needs in order to fly on a commercial airline. You cannot bring your own oxygen on board, you must use airline supplied oxygen. Requirements vary from carrier to carrier but, they all require arrangements be made in advance and they all charge for in flight oxygen, which would be a considerable cost for the diver who requires a full face mask for appropriate treatment.

Airlines charge for oxygen by either flight (with each time you change planes being considered a separate flight) or by the amount of oxygen used. Therefore if possible it is better and can be less expensive to take a direct flight. Airlines don’t provide oxygen for in-terminal use, these arrangements must be made separately. (Note: Some first aid stations in airports have oxygen available). Some cylinders have a flow meter that adjusts from two liters to eight liters, while others offer either a low flow (2 LM) or high flow (4 LM). Most airlines will allow you to carry an empty portable tank either on board or checked with baggage.

Air travel decreases the partial pressure of oxygen in the blood and may cause symptoms in treated divers without supplemental oxygen. This has the possibility of further injury to the ischemic penumbra of the neurological injury of the accident. It is not known whether or not the airlines have the capability of full mask oxygen delivery. In general, supplemental oxygen should be considered if the arterial PaO2 is likely to 50 mm or less during flight. Inflight PaO2 may be estimated by measuring ground-level PaO2 and the FEV1 (as a percent of the predicted FEV1). The following formula was derived by Dillard and colleagues: In flight PaO2 = 0.453*(Ground PaO2) + 0.386*(FEV1%) + 2.44

Propriety of Commercial Flight in Divers with Residua?

Dr. Nick McIver brings up the question of the impropriety of commercial flight (even with 100% oxygen) in the treated diver clearly with residua. His group would not advise that based on occasional unexpected exaccerbation in flight after treatment. They would give HBO on site until maximal resolution achieved and then still advise delay before return flight. (In some cases for up to 2 weeks). They have not requested in-flight oxygen over which there are many practical and medicolegal implications. (See below).

Dr. David Elliott states that this can be done but should be for someone who has had all the recompression that was appropriate before flying. He relates an interesting case that illustrates the situation nicely.

“Case about 6 years ago: Young woman with neurological dci treated after delay very well by Indonesian Navy with two extended USN recompressions plus ancillaries. Left with a few residua and an odd cerebral deficit, she remained fluent in her two natural languages, English and Italian, but lost her ability to act as professional interpreter. She had some days post-recompression, with some HBOs, on the ground before flying to Europe and I was still concerned about altitude hypoxia in the regions of the inevitable ischaemic penumbra. After discussion with a senior flying doctor of British Airways, they had time to bring together every oxygen bottle they had so that they had enough to give her continuous O2 for the 12-hour flight to Heathrow. The dose was around 3 L/min, calculated to maintain her at ground-level pO2. She had no relapse.”

For those who need continuing repetitive HBOs after an inadequate first recompression, then they should have had a more extensive treatment locally before considering transport. If one is stuck with significant residua and inadequate local hyperbaric services then the usual emergency evacuation procedures should apply particularly if planning to fly within 5 days or so.

Why is the Oxygen Being Given?

Paul Sheffield, PhD believes that “I think that there would be an issue with the purpose of providing the diver with oxygen. A diver whose bubbles are resolved through effective HBO2 treatment should not need oxygen. And a diver who still has bubbles will get worse on ascent because of Boyles Law, even on oxygen. In either case, I would think that the airlines would want to avoid the liability.

The current oxygen and mask system on the airlines might not be sufficient. Since oxygen is given to the diver, not to give oxygen per se, but to eliminate nitrogen, a tightly fitting mask would be required and massive amounts of oxygen be required for extended overseas flights. “

Airline Issues

Then there are ‘airline’ issues that can be over-riding. Dr. Dean Heimbach feels that “this is a complex problem. The airlines position on routine use of their oxygen in the transport of patients is that they are not in the business of transporting sick folks. There are unique liabilty problems in so doing and regulations which must be followed when they act in the position of an air ambulance. There is also the problem of them competing with the air ambulance companies. Allowing medical attendants working for medical assistance companies to use their own oxygen presents its own set of problems. These include liabilty for the use of oxygen on board an aircraft when the oxygen was not provided by the airline.”

Other ‘airline’ issues regarding carrying oxygen tanks not provided by the airline include “DOT regulations that passengers not carry ANY pressurized containers, increased risk of combustion/explosion in event of any type of fire, use of cylinders to disguise terrorist devices/gases and concern that transporting patient on O2 may be considered a medical procedure/treatment that is outside liability insurance of carrier.” Larry ‘Harris’ Taylor, PhD succinctly summarizes his remarks above by stating “In other words, this is most LIKELY a situation where medicine and common sense must bow to other concerns of the passenger carrier.”

Also from the airline’s point of view is the fact that other customers (passengers) are paying large sums for the flight, and the airline’s first service obligation is as a carrier not as an air ambulance. Moreover the airlines do not want to be ambulances.

Maida Taylor, MD, MPH states, “Occasionally they will take a very sick person on board for transit to a hospital. Often a full medical team is on board, an entire section sealed off for the stretcher, and the price almost equals that of a private medical evacuation. Remember also that in remote places, commercial flights are scheduled at very wide intervals, and often service is unpredictable due to the poor local service management. In an dive emergency it is seemingly better to scramble that private air ambulance for best outcomes…. “

Other Valuable Information

The Air Carrier Access Act and the DOT rule that implements it set out procedures designed to ensure that these individuals have the same opportunity as anyone else to enjoy a pleasant flight. Here are some of the major provisions of the rule.

* A person may not be refused transportation on the basis of disability or be required to have an attendant or produce a medical certificate, except in certain limited circumstances specified in the rule.

* Airlines must provide enplaning, deplaning and connecting assistance, including both personnel and equipment. (Some small commuter aircraft may not be accessible to passengers with severe mobility impairments. When making plans to fly to small cities, such passengers should check on the aircraft type and its accessibility.)

* Airport terminals and airline reservations centers must have TDD telephone devices for persons with hearing or speech impairments.

* Passengers with vision or hearing impairments must have timely access to the same information given to other passengers at the airport or on the plane concerning gate assignments, delayed flights, safety, etc.

* New widebody aircraft must have a wheelchair- accessible lavatory and an on-board wheelchair. Airlines must put an on-board wheelchair on most other flights upon a passenger’s request (48 hours notice required).

* Air carriers must accept wheelchairs as checked baggage, and cannot require passengers to sign liability waivers for them (except for pre-existing damage).

* Most new airplanes must have movable armrests on half the aisle seats, and on-board stowage for one folding passenger wheelchair.

* Carriers must allow service animals to accompany passengers in the cabin, as long as they don’t block the walkways.

* FAA safety rules establish standards for passengers allowed to sit in emergency exit rows; such persons must be able to perform certain evacuation-related functions.

* FAA rules also prohibit passengers from bringing their own oxygen. Most airlines will provide aircraft-approved oxygen for a fee, but aren’t required to.

* Airlines may not charge for services that are required by this rule.

* Airlines must make available a specially-trained Complaints Resolution Official if a dispute arises. There must be a copy of the DOT rule at every airport.
It’s wise to call the airline again before your trip to reconfirm any assistance that you have requested.

AUTHOR

Ernest S. Campbell, M.D., FACS

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