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THE MERCK MANUAL MEDICAL LIBRARY: The Merck Manual of Medical Information--Home Edition
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Problems in Transit

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Several conditions are common even among healthy people while in transit.

Motion Sickness

Motion sickness during air, sea, rail, bus, or car travel occurs when the brain receives conflicting signals about movement (see Dizziness and Vertigo: Motion Sickness). Motion sickness is often triggered by turbulence and vibration and made worse by warmth, anxiety, hunger, or overeating. The main symptoms are stomach upset, nausea, vomiting, sweating, and dizziness (vertigo).

Motion sickness can be minimized by the following measures:

  • Moderating intake of food, fluids, and alcohol (before and during travel)
  • Fixing the eyes on a stationary object or on the horizon
  • Lying down and keeping the eyes closed
  • Choosing a seat where motion is felt least (for example, in the center of an airplane, over the wing)
  • Refraining from reading
  • Sitting by an open window or an air vent if possible

A cabin in the middle of a ship close to water level may reduce motion sickness in some people. A scopolamine Some Trade Names
TRANSDERM SCOP
patch (which requires a prescription) or over-the-counter or prescription antihistamines are often useful, especially if taken before travel. However, these drugs often cause drowsiness, light-headedness, and dry mouth and can result in confusion, falls, and other problems in older people.

Blood Clots

Blood clots can occur when people sit for long periods during air, rail, bus, or car travel. Blood clots (deep vein thrombosis—see Venous Disorders: Deep Vein Thrombosis (DVT)) are more common in people who

  • Are older
  • Are overweight
  • Smoke cigarettes
  • Have varicose veins
  • Are taking estrogen
  • Are pregnant
  • Have recently undergone surgery
  • Have had blood clots previously
  • Have been inactive or immobile

Blood clots form in leg or pelvic veins and occasionally dislodge and travel to the lungs (pulmonary emboli—see Pulmonary Embolism (PE): Pulmonary Embolism). Some blood clots in the legs do not cause symptoms, whereas others cause cramping, swelling, and color changes of the calves and feet. Pulmonary emboli are much more serious than leg blood clots. People may first develop a sensation of not feeling well, followed by shortness of breath, chest pain, or fainting. Pulmonary emboli are sometimes fatal.

The risk of developing blood clots can be reduced by changing positions frequently, straightening and moving the legs frequently while seated, drinking enough fluids, and getting up to walk and stretch every 1 to 2 hours. Prolonged leg crossing may decrease leg circulation and should be avoided. Avoiding caffeine and alcohol and wearing elastic support stockings also reduce risk.

Ear and Sinus Pressure

Ear and sinus pressure while flying is the result of changes in air pressure (cabin pressure). Normally, as an airplane takes off and climbs (ascends), cabin pressure decreases, and small pockets of air trapped in the sinuses and middle ear expand, leading to ear pressure, ear “popping,” or both, and mild sinus pressure or discomfort. As an airplane descends, cabin pressure increases, and similar symptoms occur. These mild sensations usually disappear as air pressure in the sinuses and ears equalizes with cabin pressure. Untreated dental problems or teeth subject to recent dental procedures also may become painful when air pressure changes.

Swallowing (particularly while holding the nose closed) frequently or yawning during ascent and descent helps equalize pressure. Some people suck on hard candies during descent. These actions are normally sufficient to relieve minor ear and sinus discomfort. With allergies, sinus problems, and head colds, however, the passages that connect the ears and sinuses to the nose and mouth become inflamed and sometimes blocked by mucus, which prevents air pressure from equalizing normally. People with these problems may experience significant discomfort. They may benefit from taking decongestants before flying or by blowing hard against a closed mouth and pinched nostrils to equalize air pressure.

Children are particularly susceptible to the pain of unequal air pressure. They should chew gum, suck hard candy, or be given something to drink during ascent and descent to encourage swallowing. Babies can be breastfed or given a bottle or pacifier.

Sleep Disturbance

Sleep disturbance (jet lag) is common with air travel across more than 3 time zones. Sleep disturbance does not occur with sea, rail, or car travel because travelers have time to adjust to time zone changes. The most obvious symptom is fatigue on arrival. Other symptoms include irritability, difficulty sleeping (insomnia), headache, and difficulty concentrating. Jet lag can be minimized by starting to adjust sleep and wake times 1 or 2 days before departure to coincide with those of the destination time zone. In flight, a person should drink plenty of fluids and avoid smoking, caffeine, and excessive alcohol. Managing exposure to light also can help travelers adjust to a new time zone.

Westward Travel: People traveling westward tend to awaken earlier and feel tired earlier than they should by local time. For example, if people who normally wake up at 7 am and go to bed at 11 pm travel 3 time zones west, they tend to awaken at 4 am local time and feel the need for sleep by 8 pm. To adjust, people should try to get bright sunlight in the late afternoon and try to stay up until the appropriate bedtime.

Eastward Travel: People traveling eastward tend to awaken later and stay awake longer than they should by local time. For example, if people who normally wake up at 7 am and go to bed at 11 pm travel 3 time zones east, they tend to awaken at 10 am local time and not feel the need for sleep until 2 am. To adjust, people should get bright sunlight in the early morning. Those who had an overnight flight should try to remain physically active until evening and try not to nap.

Short-acting sedatives may help people fall asleep at the appropriate local time after eastward travel. However, sedatives may cause side effects, such as daytime drowsiness, amnesia, and nighttime insomnia. Long-acting sedatives, such as diazepam Some Trade Names
DIASTATVALIUM
, can also cause confusion and falls in older people and should be avoided.

The hormone melatonin regulates the sleep-wake cycle. Some doctors have recommended using melatonin supplements after eastward travel to reset the body's internal clock for sleep. Although some travelers report melatonin is beneficial, its effectiveness and safety have not been thoroughly proved.

Dehydration

Dehydration while flying is common because of the low humidity in airplanes. Dehydration tends to affect older people and people with certain medical conditions, such as diabetes and disorders requiring treatment with drugs used to increase sodium and water excretion in the urine (diuretics). The main symptoms are light-headedness, drowsiness, confusion, and, occasionally, fainting. Dehydration can be prevented by drinking fluids and by avoiding alcohol and caffeine. Dry skin can be treated with moisturizers.

Spread of Infection

Spread of infection on airplanes and cruise ships often receives media attention but is relatively uncommon. Concern is greatest for influenza, viral diarrhea, and bacterial meningitis. Travelers can minimize their risk of influenza by making sure they have received the most current influenza vaccine. They can minimize their risk of diarrhea by washing their hands frequently. There is no reliable way to prevent bacterial meningitis. Some cruise ships offer antibiotics to passengers who have been in close contact with passengers who have these infections.

Minor Injuries

Minor injuries are common. Unaccustomed lifting of heavy luggage is a common cause of shoulder injuries. Luggage falling out of overhead storage bins can cause other significant injuries. During ship travel, injuries can be prevented by wearing shoes that provide good traction on wet surfaces, using handrails and removing sunglasses before entering ship stairwells, and remaining alert in unfamiliar surroundings. A flashlight is useful for preventing falls at night as well.

Anxiety

Anxiety affects many people who travel. Fear of flying, fear of confined spaces, and worries about medical conditions worsening during flight are common sources of anxiety. Anxiety can cause insomnia, making jet lag worse. People may hyperventilate, often with symptoms such as chest pain, trouble breathing, muscle spasms, and tingling in the arms and hands and around the mouth. Companionship with a seasoned traveler or caretaker may help relieve anxiety. Cognitive therapy and desensitization programs or hypnosis may also help. Sedatives or antianxiety drugs, such as zolpidem Some Trade Names
AMBIEN
or alprazolam Some Trade Names
XANAX
, may be of benefit as well (see Antianxiety DrugsTables).

Last full review/revision February 2009 by Christopher Sanford, MD, MPH

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