Medical Advice for Commercial Air TravelersMay 14, 2001
Family physicians are frequently asked to make recommendations to patients before they travel aboard commercial aircraft, and the need for such advice is also increasing. The need to understand basic aerospace physiology has been accelerated by the growing number of passengers who use commercial air travel and, in particular, the increasing number of elderly, disabled or chronically ill passengers. Although commercial air transportation is very safe compared with other forms of transportation, both environmental and health concerns must be considered when counseling patients who are about to travel by air.
On-board resources for a medical emergency during flight are severely limited, and the only medications consistently carried on U.S. aircraft are epinephrine, diphenhydramine (Benadryl) and nitroglycerin.
The Air Carrier Access Act of 19861 required the U.S. Department of Transportation to develop regulations to ensure that persons with disabilities are treated without discrimination in any way, consistent with the safe carriage of all passengers. Because of Air Carrier Access rules, people with medical conditions who might not have selected airline travel in the past are now regularly attempting to use this mode of transportation. However, if legitimate medical acceptance issues arise, a medical certificate from the treating physician stating that the passenger is medically stable for air travel and will not require extraordinary medical assistance during the flight may be required. This request for a medical certificate is based on information provided by the passenger regarding a specific health condition or may be required when an arriving passenger is visibly ill. The Aerospace Medical Association (telephone: 703-739-2240) monograph "Medical Guidelines for Airline Travel"2 is a useful guide for physicians providing these determinations.
Contents of Airline Emergency Medical Kits*
Oropharyngeal airways (3 sizes)/3
Syringes (different sizes, 2 sets)/4
Needles (different sizes, 2 sets)/6
50% dextrose injection, 50 mL/1
Epinephrine 1:1,000, single-dose ampule/2
Injectable diphenhydramine (Benadryl), single-dose ampule/2
Instructions for use of medications/1
Protective latex gloves or equivalent/1 pair
*--As required by the Federal Aviation Administration.
Federal Air Regulations (FARs) require all U.S.based airlines to carry a basic emergency medical kit with specified contents (Table 1), as well as a first-aid kit for emergencies that may occur during flight. However, the contents of the kits are limited and are intended for basic emergency treatment only, not to sustain or treat critically ill passengers on extended flights. The medical kit may be opened during flight only when authorized by a physician, either on board or from the airline's medical department connected to the aircraft via air-to-ground communications. In addition, a number of airlines have installed automatic external defibrillators on board aircraft and have trained flight attendants in their use. The Aviation Medical Assistance Act of 19983 requires the Federal Aviation Administration to study the additional medical equipment and training that should be required based on analyses of the frequency of medical incidences encountered and to issue a future Notice of Proposed Rulemaking to modify the current FAR. Some airlines have begun installing enhanced medical kits containing a wide variety of acute cardiac life support drugs and equipment to aid in medical emergencies.
Supplemental oxygen is available on an emergency basis during flights but often is limited to flow rates of 2 and 4 L per minute, and the supply is strictly limited. Passengers with stable medical conditions requiring low-flow oxygen cannot bring their own oxygen on board, according to FARs concerning hazardous cargo (empty oxygen containers are allowed to be transported as baggage). Most air carriers will provide oxygen, either with adjustable (2 to 8 L per minute) or nonadjustable (low flow at 2 L per minute or high flow at 4 L per minute) flow meters. There is a fee for this service, either charged per unit of oxygen used or per ticket coupon (one coupon per boarding), and a minimum notice of 24 to 48 hours or longer is required, along with a medical certificate from the passenger's physician certifying that the person is medically cleared to fly at a relative cabin altitude of 8,000 feet and specifying the flow rate, whether intermittent or continuous, and type of delivery mask (face mask or nasal cannula) to be used.
Passengers who require oxygen for stable medical conditions cannot bring their own supplies and equipment and must arrange for oxygen to be made available on board, at layovers and at final destinations.
Oxygen is supplied as either large-cylinder (3,228 L) or small-cylinder (300 L) compressed gas.4 Passengers must arrange for oxygen to be available during airport layovers by contacting a local supplier in the layover city or through their home oxygen service, with advance notice of at least 24 hours to ensure delivery. Other types of medical respiratory equipment, such as nebulizers or pediatric mechanical ventilators, may sometimes be allowed to be used on board, but their usage must be pre-approved to prevent interference with sensitive aviation electronic equipment and must conform to applicable FARs specifications.
Although flying is generally a safe and comfortable method of transportation, several environmental and physiologic stresses may be encountered in modern commercial aircraft. These include but are not limited to preflight activities, lowered barometric pressure and partial pressure of oxygen, sustained periods of noise and vibration exposure, turbulence, variable air circulation, environmental temperature changes, low humidity, disruption of circadian rhythms, sustained periods of postural immobility and varying exposure to low-level radiation.5 In addition, smoking during flight is still allowed by many international carriers, although smoking is banned on all domestic flights in the United States. Factors such as length of flight and class of ticket purchased must be considered in assessing the impact of these environmental and physiologic stresses.
Commercial air travel is inadvisable for anyone with a preflight sea level PaO2 measurement below 68 to 70 mm Hg, unless supplemental oxygen can be arranged.
Commercial jet aircraft maintain a relative cabin altitude between 5,000 and 8,000 feet during routine flight, with the FARs specifying that an 8,000-foot environment be maintained even at the highest operating altitude.