on the many domestic and international airlines. It has
been predicted that in the coming two decades, the
number of passengers will double. A global increase in
travel, as well as an increasingly aged population in
many countries, makes it reasonable to assume that
there will be a significant increase in older passengers
and passengers with illness. Patients frequently ask
their physicians whether or not it is advisable for them
to travel, and if so, what precautions they should take.
Consequently, physicians need to be aware of the environmental
and physiological stresses of flight in order
to properly advise their patients. In addition, because
international travelers can fly to the four corners of the
world in just hours, a basic understanding of vaccinations
is requisite.
Two caveats are brought to the attention of the
reader. First, if inflight illness or even death has occasionally
been reported by the airlines, the event was not
necessarily caused by airline travel or the stresses of
flight. The physician must be mindful that, with so
many passengers spending so many hours inflight, flying
and the medical event may be coincidental rather
than causal. Second, the guidelines described herein are
just that– guidelines, and not rigid criteria or hard and
fast rules. Like all patient management, these guidelines
must be individualized and tempered by the physician’s
clinical judgment.
This publication was prepared by the Aerospace
Medical Association Medical Guidelines Task Force.
The information contained herein is for primary care
and specialist physicians so they will be better prepared
to advise patients who are contemplating air travel.
(The reader is cautioned that the material applies only
to passengers and not to airline crews or cabin attendants.)
The authors sincerely hope that this publication
will educate the physician and contribute to safe and
comfortable flight for passengers.
Stresses of Flight
Modern commercial aircraft are very safe and, in
most cases, reasonably comfortable. However, all
flights, short or long haul, impose stresses on all passengers.
Preflight stresses include airport tumult on the
ground such as carrying baggage, walking long distances,
and being delayed. Inflight stresses include lowered
barometric pressure and partial pressure of oxygen,
noise, vibration (including turbulence), cigarette
smoke, uncomfortable temperatures and low humidity,
jet lag, and cramped seating (64). Nevertheless, healthy
passengers endure these stresses which, for the most
part, are quickly forgotten once the destination is
reached. In general, passengers with illness (i.e., stable
illness) also usually depart the destination airport none
the worse. However, there is always the potential for
such passengers to become ill during or after the flight
due to these stresses.
The primary difference between the aircraft environment
and the ground environment relates to the atmosphere.
Contrary to popular belief, modern aircraft are
not pressurized to sea level equivalent. Instead, on most
flights the cabin altitude will be between 5000 and 8000
ft (1524 m and 2438 m). This results in reduced barometric
pressure with a concomitant decrease in partial
pressure of oxygen (PO2). While the barometric pressure
is 760 mm Hg at sea level with a corresponding PaO2
(arterial O2 pressure) of 98 mm Hg, the barometric
pressure at 8000 ft will be 565 mm Hg with PaO2 of about
55 mm Hg. If these last data are plotted on the oxyhemoglobin
dissociation curve, we obtain a blood oxygen
saturation of 90%. Although most healthy travelers can
normally compensate for this amount of hypoxemia,
this may not be true for coronary, pulmonary, cerebrovascular,
and anemic patients. Because these patients
may already have a reduced PaO2 on the ground, further
reduction in aircraft cabin pressure will bring them to
the steep part of the oxyhemoglobin dissociation curve
with a resultant very low saturation, which could cause
distress and/or exacerbation of their illness (Fig. 1).
The hazards of cigarette smoking, active and passive,
are well known and need not be recounted here. There
is a worldwide movement to ban inflight smoking, with
the International Civil Aviation Organization (ICAO)
having asked all member States to comply. U.S. air
carriers prohibit smoking on all flights. As a result,
there has been vast improvement in cabin air quality
and commensurate crew and passenger comfort. (For
passengers with the potential for inflight nicotine withdrawal
symptoms, nicotine gum or patch might be
considered.)
Today’s aircraft have very low cabin humidity, usually
ranging from 10-20%. This is unavoidable because
the air at high altitude is practically devoid of moisture.
As a result, there can be a drying effect of airway
passages, the cornea (particularly under contact lenses),
and the skin.
Jet lag or circadian desynchronosis results from the
desynchronization of the body clock with surroundingenvironmental cues. It may not only be an annoyance
for healthy passengers, but it can also complicate the
timing of medications, such as insulin (See Jet Lag and
Diabetes sections).
On commercial flights, regardless of aircraft type,
many passengers sit in small, cramped spaces. This is
not only uncomfortable, but also reduces the opportunity
to get up, stretch, and walk about the cabin. Sitting
for long periods is tolerable for most passengers, but for
some there is the potential for exacerbating peripheral
edema, cramps, and other circulatory problems. Of particular
concern are deep venous thrombosis and, even
worse, the potential for pulmonary embolus (See Deep
Venous Thrombosis section).
been predicted that in the coming two decades, the
number of passengers will double. A global increase in
travel, as well as an increasingly aged population in
many countries, makes it reasonable to assume that
there will be a significant increase in older passengers
and passengers with illness. Patients frequently ask
their physicians whether or not it is advisable for them
to travel, and if so, what precautions they should take.
Consequently, physicians need to be aware of the environmental
and physiological stresses of flight in order
to properly advise their patients. In addition, because
international travelers can fly to the four corners of the
world in just hours, a basic understanding of vaccinations
is requisite.
Two caveats are brought to the attention of the
reader. First, if inflight illness or even death has occasionally
been reported by the airlines, the event was not
necessarily caused by airline travel or the stresses of
flight. The physician must be mindful that, with so
many passengers spending so many hours inflight, flying
and the medical event may be coincidental rather
than causal. Second, the guidelines described herein are
just that– guidelines, and not rigid criteria or hard and
fast rules. Like all patient management, these guidelines
must be individualized and tempered by the physician’s
clinical judgment.
This publication was prepared by the Aerospace
Medical Association Medical Guidelines Task Force.
The information contained herein is for primary care
and specialist physicians so they will be better prepared
to advise patients who are contemplating air travel.
(The reader is cautioned that the material applies only
to passengers and not to airline crews or cabin attendants.)
The authors sincerely hope that this publication
will educate the physician and contribute to safe and
comfortable flight for passengers.
Stresses of Flight
Modern commercial aircraft are very safe and, in
most cases, reasonably comfortable. However, all
flights, short or long haul, impose stresses on all passengers.
Preflight stresses include airport tumult on the
ground such as carrying baggage, walking long distances,
and being delayed. Inflight stresses include lowered
barometric pressure and partial pressure of oxygen,
noise, vibration (including turbulence), cigarette
smoke, uncomfortable temperatures and low humidity,
jet lag, and cramped seating (64). Nevertheless, healthy
passengers endure these stresses which, for the most
part, are quickly forgotten once the destination is
reached. In general, passengers with illness (i.e., stable
illness) also usually depart the destination airport none
the worse. However, there is always the potential for
such passengers to become ill during or after the flight
due to these stresses.
The primary difference between the aircraft environment
and the ground environment relates to the atmosphere.
Contrary to popular belief, modern aircraft are
not pressurized to sea level equivalent. Instead, on most
flights the cabin altitude will be between 5000 and 8000
ft (1524 m and 2438 m). This results in reduced barometric
pressure with a concomitant decrease in partial
pressure of oxygen (PO2). While the barometric pressure
is 760 mm Hg at sea level with a corresponding PaO2
(arterial O2 pressure) of 98 mm Hg, the barometric
pressure at 8000 ft will be 565 mm Hg with PaO2 of about
55 mm Hg. If these last data are plotted on the oxyhemoglobin
dissociation curve, we obtain a blood oxygen
saturation of 90%. Although most healthy travelers can
normally compensate for this amount of hypoxemia,
this may not be true for coronary, pulmonary, cerebrovascular,
and anemic patients. Because these patients
may already have a reduced PaO2 on the ground, further
reduction in aircraft cabin pressure will bring them to
the steep part of the oxyhemoglobin dissociation curve
with a resultant very low saturation, which could cause
distress and/or exacerbation of their illness (Fig. 1).
The hazards of cigarette smoking, active and passive,
are well known and need not be recounted here. There
is a worldwide movement to ban inflight smoking, with
the International Civil Aviation Organization (ICAO)
having asked all member States to comply. U.S. air
carriers prohibit smoking on all flights. As a result,
there has been vast improvement in cabin air quality
and commensurate crew and passenger comfort. (For
passengers with the potential for inflight nicotine withdrawal
symptoms, nicotine gum or patch might be
considered.)
Today’s aircraft have very low cabin humidity, usually
ranging from 10-20%. This is unavoidable because
the air at high altitude is practically devoid of moisture.
As a result, there can be a drying effect of airway
passages, the cornea (particularly under contact lenses),
and the skin.
Jet lag or circadian desynchronosis results from the
desynchronization of the body clock with surroundingenvironmental cues. It may not only be an annoyance
for healthy passengers, but it can also complicate the
timing of medications, such as insulin (See Jet Lag and
Diabetes sections).
On commercial flights, regardless of aircraft type,
many passengers sit in small, cramped spaces. This is
not only uncomfortable, but also reduces the opportunity
to get up, stretch, and walk about the cabin. Sitting
for long periods is tolerable for most passengers, but for
some there is the potential for exacerbating peripheral
edema, cramps, and other circulatory problems. Of particular
concern are deep venous thrombosis and, even
worse, the potential for pulmonary embolus (See Deep
Venous Thrombosis section).
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