Chapter 6Conveyance & Transportation Issues
Worldwide, >1 billion people travel by commercial aircraft every year, and this number is expected to double in the next 20 years. Travelers often have concerns about the health risks of flying in airplanes. Those with underlying illness need to be aware that the entire point-to-point travel experience, including buses, trains, taxis, and public waiting areas, can pose challenges. While illness may occur as a direct result of air travel, it is uncommon; the main concerns are:
- Exacerbations of chronic medical problems due to changes in air pressure, humidity, and oxygen concentration
- Relative immobility during flights (risk of thromboembolic disease, see Chapter 2, Deep Vein Thrombosis & Pulmonary Embolism)
- Close proximity to other passengers with certain communicable diseases
- Spraying of airplane cabins with insecticides (disinsection) before landing in certain destinations
EXACERBATION OF CHRONIC DISEASE
During flight, the aircraft cabin pressure is usually maintained at the equivalent of 6,000–8,000 ft (1,829–2,438 m) above sea level. Most healthy travelers will not notice any effects. However, for travelers with cardiopulmonary diseases (especially those who normally require supplemental oxygen), cerebrovascular disease, anemia, or sickle cell disease, conditions in an aircraft can exacerbate underlying medical conditions. Aircraft cabin air is typically dry, usually 10%–20% humidity, which can cause dryness of the mucous membranes of the eyes and airways.
People with chronic illnesses, particularly those whose conditions may be unstable, should be evaluated by a physician to ensure they are fit for air travel. For those who require supplemental in-flight oxygen, the following must be taken into consideration:
- Federal regulations prohibit airlines from allowing passengers to bring their own oxygen aboard; passengers requiring in-flight supplemental oxygen should notify the airline ≥72 hours before departure.
- Information regarding the screening of respiratory equipment (such as oxygen canisters or portable oxygen concentrators) at airports in the United States and regulations regarding oxygen use on aircraft can be found at www.tsa.gov/traveler-information/portable-oxygen.
- Airlines might not offer in-flight supplemental oxygen on all aircraft or flights; some airlines permit only portable oxygen concentrators.
- Travelers must arrange their own oxygen supplies while on the ground, at departure, during layovers, and on arrival. The National Home Oxygen Patients Association provides information to assist patients who require supplemental oxygen during travel (www.homeoxygen.org/airtrav.html).
BAROTRAUMA DURING FLIGHT
Barotrauma may occur when the pressure inside an air-filled, enclosed body space (such as the middle ear, sinuses, or abdomen) is not the same as air pressure inside the aircraft cabin. It most commonly occurs during rapid changes in environmental pressure, such as during ascent, when cabin pressure rapidly decreases, and during descent, when cabin pressure rapidly increases. Barotrauma most commonly affects the middle ear; it occurs when the eustachian tube is blocked and thus unable to equalize the air pressure in the middle ear with the outside cabin pressure. Middle ear barotrauma is usually not severe or dangerous and can usually be prevented or self-treated. It may rarely cause complications such as a perforated tympanic membrane, dizziness, permanent tinnitus, or hearing loss. The following suggestions may help avoid potential barotrauma:
- People with ear, nose, and sinus infections or severe congestion may wish to temporarily avoid flying to prevent pain or injury.
- Oral pseudoephedrine 30 minutes before flight departure, or a nonsteroidal anti-inflammatory agent, may alleviate symptoms.
- Travelers with allergies should continue their regular allergy medication.
- Travelers should stay hydrated to help avoid irritation of nasal passages and pharynx and to promote better function of the eustachian tubes.
- Travelers sensitive to abdominal bloating should avoid carbonated beverages and foods that can increase gas production.
- People who have had recent surgery, particularly intra-abdominal, neurologic, intrapulmonary, or intraocular procedures, should consult with their physicians before flying.
VENTILATION AND AIR QUALITY
All commercial jet aircraft built after the late 1980s and a few modified older aircraft recirculate 10%–50% of the air in the cabin mixed with outside air. The recirculated air passes through a series of filters 20–30 times per hour. In most newer-model airplanes, the recycled air passes through high-efficiency particulate air (HEPA) filters, which capture 99.9% of particles (bacteria, fungi, and larger viruses) 0.1–0.3 µm in diameter. Air flow occurs transversely across the plane in limited bands, and air is not forced up and down the length of the plane. As a result, the air cabin environment is not conducive to the spread of most infectious diseases.
IN-FLIGHT MEDICAL EMERGENCIES
Increasingly, large aircraft, combined with an aging flying population, makes the incidence of onboard medical emergencies likely to increase. Approximately 1 in 10,000 to 40,000 passengers has a medical incident during air transport. Of these, approximately 1 in 150,000 requires use of in-flight medical equipment or drugs. The most commonly encountered in-flight medical events, in order of frequency, are the following:
- Vasovagal syncope
- Gastrointestinal events
- Respiratory events
- Cardiac events
- Neurologic events
Deaths aboard commercial aircraft have been estimated at 0.3 per 1 million passengers; approximately two-thirds of these are caused by cardiac problems. Air carriers in the United States that fly with a maximum payload capacity of >7,500 pounds and with ≥1 flight attendant (typically those aircraft with a capacity of ≥30 passengers) are now required to carry ≥1 approved automatic external defibrillator and an emergency medical kit. The kit is required to have the items specified by the Federal Aviation Administration (for contents, see www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22516).
Although flight attendants receive training in basic first aid procedures, they are generally not certified in emergency medical response. Many airlines use ground-based medical consultants via radio or phone communication to assist volunteer passenger responders and flight attendants in managing medical cases.
The goal of managing in-flight medical emergencies is to stabilize the passenger until ground-based medical care can safely be reached; it should not be considered a method of maintaining the original flight route in order to reach the scheduled destination. The captain must, therefore, weigh the needs of the ill passenger with other safety considerations such as weather, landing conditions, and terrain. Certain routes, such as transoceanic flights, may severely restrict diversion options, while others may present a number of safe landing choices. In the latter circumstance, consideration should be given to choosing an airport that has timely access to a medical facility.
IN-FLIGHT TRANSMISSION OF COMMUNICABLE DISEASES
Communicable diseases may be transmitted to other travelers during air travel; therefore, people who are acutely ill, or still within the infectious period for a specific disease, should delay their travel until they are no longer contagious. Travelers should be up-to-date on routine vaccinations and receive destination-specific vaccinations before travel. Travelers should be reminded to wash their hands frequently and thoroughly (or use an alcohol-based hand sanitizer containing ≥60% alcohol), especially after using the toilet and before preparing or eating food, and to cover their noses and mouths when coughing or sneezing.
If a passenger with a communicable disease is identified as having flown on a particular flight (or flights), passengers who may have been exposed may be contacted by public health authorities for possible screening or prophylaxis. When necessary, public health authorities will obtain contact information from the airline for potentially exposed travelers so they may be contacted and offered intervention. Notifying a passenger of potential exposure to a communicable disease during a flight is facilitated if he or she has provided the airline with accurate and up-to-date contact information.
Mycobacterium tuberculosis is transmitted from person to person via airborne respiratory droplet nuclei. Although the risk of transmission onboard aircraft is low, CDC recommends conducting passenger contact investigations for flights ≥8 hours if the person with tuberculosis (TB) is sputum smear positive for acid-fast bacilli and has cavitation on chest radiograph or has multidrug-resistant TB. People known to have active TB disease should not travel by commercial air (or any other commercial means) until they are determined to be noninfectious. State health department TB controllers are valuable resources for advice (www.tbcontrollers.org/community/statecityterritory).
Meningococcal disease (caused by Neisseria meningitidis) is transmitted by direct contact with respiratory droplets and secretions and can be rapidly fatal. Therefore, close contacts need to be quickly identified and provided with prophylactic antimicrobial agents. Antimicrobial prophylaxis should be considered for any of the following:
- Household member traveling with the ill traveler
- Travel companion with very close contact
- Passenger seated directly next to the ill traveler on flights ≥8 hours
Measles (rubeola) is a viral illness transmitted by respiratory droplets or direct contact, but it can also be spread via airborne routes. Most measles cases diagnosed in the United States are imported from countries where measles is endemic. Travelers should ensure they are immune to measles before travel. Infants aged 6–11 months who will be traveling overseas should receive 1 dose of measles-mumps-rubella (MMR) vaccine before travel. However, this dose will not count as part of the recommended immunization schedule of 2 doses, which begins at age 12–15 months. An ill traveler is considered infectious during a flight of any duration if he or she traveled during the 4 days before rash onset through 4 days after rash onset. Flight-related contact investigations are initiated as quickly as possible so postexposure prophylaxis may be provided to susceptible travelers. MMR vaccine given within 72 hours of exposure or immune globulin given within 6 days of exposure may prevent measles or minimize its severity.
Transmission of the influenza virus aboard aircraft has been documented, but data are limited. Transmission is thought to be primarily due to large droplets; therefore, passengers seated closest to the source case are believed to be most at risk for exposure. Influenza vaccine is routinely recommended each year for all people aged ≥6 months who do not have contraindications.
See the CDC Travelers’ Health website (www.cdc.gov/travel and wwwnc.cdc.gov/travel/page/air-travel-cruise-ships.htm) for additional information. Travel advice specific for air crews may be found in Chapter 8.
To reduce the accidental spread of mosquitoes and other vectors via airline cabins and luggage compartments, a number of countries require disinsection of all inbound flights. The World Health Organization (WHO) and the International Civil Aviation Organization (ICAO) specify 2 approaches for aircraft disinsection:
- Spraying the aircraft cabin with an aerosolized insecticide (usually 2% phenothrin) while passengers are on board
- Treating the aircraft’s interior surfaces with a residual insecticide while the aircraft is empty
Some countries use a third method, in which aircraft are sprayed with an aerosolized insecticide while passengers are not on board.
Disinsection is not routinely done on incoming flights to the United States. Although disinsection, when done appropriately, was declared safe by WHO in 1995, there is still much debate about the safety of the agents and methods used. Guidelines for disinsection have been updated for the revised International Health Regulations (www.who.int/ihr/en). Many countries, including the United States, reserve the right to increase the use of disinsection in case of increased threat of vector or disease spread. An updated list of countries that require disinsection and the types of methods used is available at the Department of Transportation website (http://ostpxweb.dot.gov/policy/safetyenergyenv/disinsection.htm).
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