MEDICAL GUIDELINES
AsMA Medical Guidelines for Air Travel: Stresses of Flight Claude Thibeault; Anthony D. Evans
INTRODUCTION:
KEYWORDS:
Medical Guidelines for Airline Travel provide information that enables healthcare providers to properly advise patients who plan to travel by air. Modern commercial aircraft are very safe and, in most cases, reasonably comfortable. However, all flights, short or long haul, impose stresses passengers. PreflightUser stresses include airport commotion on the ground Delivered byon Ingenta to: Guest such as carrying baggage, walking long distances, getting the 2016 gate on02:21:29 time, and being delayed. In-flight stresses IP: 195.34.79.224 On: Sun, 26toJun Copyright: Aerospace Association include acceleration, vibration (including turbulence),Medical noise, lowered barometric pressure, variations of temperature and humidity, and fatigue among others. Healthy passengers normally tolerate these stresses quite well; however, there is the potential for passengers to become ill during or after the flight due to these stresses, especially for those with pre-existing medical conditions and reduced physiological reserves. cabin pressure, cabin humidity, flight environment, jet lag, stress. Thibeault C, Evans AD. AsMA medical guidelines for air travel: stresses of flight. Aerosp Med Hum Perform. 2015; 86(5):486–487.
M
odern commercial aircraft are very safe and, in most cases, reasonably comfortable. However, all flights, short or long haul, impose stresses on passengers. Preflight stresses include airport commotion on the ground such as carrying baggage, walking long distances, getting to the gate on time, and being delayed. In-flight stresses include acceleration, vibration (including turbulence), noise, lowered barometric pressure, variations of temperature and humidity, and fatigue, among others.2 Nevertheless, healthy passengers normally tolerate these stresses quite well and for the most part they are quickly forgotten once the destination is reached. In general, passengers with a stable illness also usually reach the destination airport without ill effects. However, there is the potential for passengers to become ill during or after the flight due to these stresses, especially for those with pre-existing medical conditions and reduced physiological reserves. The primary difference between the aircraft cabin environment and the ground environment relates to the atmosphere, as aircraft cabins are not pressurized to sea level equivalent. Instead, on most flights the cabin altitude will be between 5000 and 8000 ft (1524 and 2438 m). This results in reduced barometric pressure with a concomitant decrease in partial pressure of oxygen (Po2). While the barometric pressure is about 760 mmHg at sea level with a typical corresponding Pao2 (arterial oxygen pressure) of 98 mmHg, the barometric pressure at 8000 ft will be about 565 mmHg, resulting in a Pao2 of 55 mmHg. If 486
AEROSPACE MEDICINE AND HUMAN PERFORMANCE Vol. 86, No. 5
these latter 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 degree of hypoxemia, this may not be true for patients having coronary, pulmonary, cerebrovascular, or anemic diseases. Because these patients may already have a reduced Pao2 on the ground, further reduction in aircraft cabin pressure could bring them to the steep part of the oxyhemoglobin dissociation curve with, potentially, a resultant very low saturation, causing distress and/ or exacerbation of their illness (Fig. 1). Today’s aircraft have low cabin humidity, usually ranging from 10–20%. This is unavoidable because the outside 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. However, there is no core dehydration if the passenger continues normal intake of fluids, but limits alcohol and caffeine.3 Fortunately, the irritant effects of tobacco smoke are no longer a significant problem, since the vast majority of airline flights are nonsmoking. For passengers with the potential for Medical Guidelines for Airline Travel provide information that enables healthcare providers to properly advise patients who plan to travel by air. These Guidelines have been peer-reviewed and also appear as a set on the AsMA website: http://www.asma.org/ publications/medical-publications-for-airline-travel/medical-guidelines-for-airline-travel. Reprint & Copyright © by the Aerospace Medical Association, Alexandria, VA. DOI: 10.3357/AMHP.4225.2015
May 2015
STRESSES OF FLIGHT—Thibeault & Evans
Delivered by Ingenta to: Guest User IP: 195.34.79.224 On: Sun, 26 Jun 2016 02:21:29 Copyright: Aerospace Medical Association Fig. 1. Oxyhemoglobin dissociation curve.
in-flight nicotine withdrawal symptoms, a variety of nicotine gum or patches can be considered, although use of so-called “electronic cigarettes” is not permitted by most airlines. Jet lag or circadian desynchronosis results from the desynchronization of the body clock with surrounding environmental cues. It may not be only an annoyance for well passengers, but it can also complicate the timing of medications, such as insulin (See Jet Lag and Diabetes sections1). On commercial flights, regardless of aircraft type, many passengers may sit in a relatively small, cramped space. 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. Immobility is also a risk factor for deep venous thrombosis (See Deep Venous Thrombosis section1). REFERENCES 1. Aerospace Medical Association. Medical guidelines for air travel. [Accessed 2014 Dec. 14.] Available from: http://www.asma.org/publications/medicalpublications-for-airline-travel/medical-guidelines-for-airline-travel. 2. Rayman RB, Davenport ED, Dominguez-Mompell R, Gitlow S, Hastings JD, et al. Clinical aviation medicine, 5th ed. New York: Castle Connolly Graduate Medical Publishing, LLC; 2013. 3. Stroud MA, Belyavin AJ, Farmer EW, Sowood PJ. Physiological and psychological effects of 24-hour exposure to a low humidity environment. Farnborough (UK): Royal Air Force Institute of Aviation Medicine; May 1992. IAM report no 705.
AEROSPACE MEDICINE AND HUMAN PERFORMANCE Vol. 86, No. 5
May 2015
487
AsMA Medical Guidelines for Air Travel: Stresses of Flight Claude Thibeault; Anthony D. Evans
INTRODUCTION:
KEYWORDS:
Medical Guidelines for Airline Travel provide information that enables healthcare providers to properly advise patients who plan to travel by air. Modern commercial aircraft are very safe and, in most cases, reasonably comfortable. However, all flights, short or long haul, impose stresses passengers. PreflightUser stresses include airport commotion on the ground Delivered byon Ingenta to: Guest such as carrying baggage, walking long distances, getting the 2016 gate on02:21:29 time, and being delayed. In-flight stresses IP: 195.34.79.224 On: Sun, 26toJun Copyright: Aerospace Association include acceleration, vibration (including turbulence),Medical noise, lowered barometric pressure, variations of temperature and humidity, and fatigue among others. Healthy passengers normally tolerate these stresses quite well; however, there is the potential for passengers to become ill during or after the flight due to these stresses, especially for those with pre-existing medical conditions and reduced physiological reserves. cabin pressure, cabin humidity, flight environment, jet lag, stress. Thibeault C, Evans AD. AsMA medical guidelines for air travel: stresses of flight. Aerosp Med Hum Perform. 2015; 86(5):486–487.
M
odern commercial aircraft are very safe and, in most cases, reasonably comfortable. However, all flights, short or long haul, impose stresses on passengers. Preflight stresses include airport commotion on the ground such as carrying baggage, walking long distances, getting to the gate on time, and being delayed. In-flight stresses include acceleration, vibration (including turbulence), noise, lowered barometric pressure, variations of temperature and humidity, and fatigue, among others.2 Nevertheless, healthy passengers normally tolerate these stresses quite well and for the most part they are quickly forgotten once the destination is reached. In general, passengers with a stable illness also usually reach the destination airport without ill effects. However, there is the potential for passengers to become ill during or after the flight due to these stresses, especially for those with pre-existing medical conditions and reduced physiological reserves. The primary difference between the aircraft cabin environment and the ground environment relates to the atmosphere, as aircraft cabins are not pressurized to sea level equivalent. Instead, on most flights the cabin altitude will be between 5000 and 8000 ft (1524 and 2438 m). This results in reduced barometric pressure with a concomitant decrease in partial pressure of oxygen (Po2). While the barometric pressure is about 760 mmHg at sea level with a typical corresponding Pao2 (arterial oxygen pressure) of 98 mmHg, the barometric pressure at 8000 ft will be about 565 mmHg, resulting in a Pao2 of 55 mmHg. If 486
AEROSPACE MEDICINE AND HUMAN PERFORMANCE Vol. 86, No. 5
these latter 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 degree of hypoxemia, this may not be true for patients having coronary, pulmonary, cerebrovascular, or anemic diseases. Because these patients may already have a reduced Pao2 on the ground, further reduction in aircraft cabin pressure could bring them to the steep part of the oxyhemoglobin dissociation curve with, potentially, a resultant very low saturation, causing distress and/ or exacerbation of their illness (Fig. 1). Today’s aircraft have low cabin humidity, usually ranging from 10–20%. This is unavoidable because the outside 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. However, there is no core dehydration if the passenger continues normal intake of fluids, but limits alcohol and caffeine.3 Fortunately, the irritant effects of tobacco smoke are no longer a significant problem, since the vast majority of airline flights are nonsmoking. For passengers with the potential for Medical Guidelines for Airline Travel provide information that enables healthcare providers to properly advise patients who plan to travel by air. These Guidelines have been peer-reviewed and also appear as a set on the AsMA website: http://www.asma.org/ publications/medical-publications-for-airline-travel/medical-guidelines-for-airline-travel. Reprint & Copyright © by the Aerospace Medical Association, Alexandria, VA. DOI: 10.3357/AMHP.4225.2015
May 2015
STRESSES OF FLIGHT—Thibeault & Evans
Delivered by Ingenta to: Guest User IP: 195.34.79.224 On: Sun, 26 Jun 2016 02:21:29 Copyright: Aerospace Medical Association Fig. 1. Oxyhemoglobin dissociation curve.
in-flight nicotine withdrawal symptoms, a variety of nicotine gum or patches can be considered, although use of so-called “electronic cigarettes” is not permitted by most airlines. Jet lag or circadian desynchronosis results from the desynchronization of the body clock with surrounding environmental cues. It may not be only an annoyance for well passengers, but it can also complicate the timing of medications, such as insulin (See Jet Lag and Diabetes sections1). On commercial flights, regardless of aircraft type, many passengers may sit in a relatively small, cramped space. 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. Immobility is also a risk factor for deep venous thrombosis (See Deep Venous Thrombosis section1). REFERENCES 1. Aerospace Medical Association. Medical guidelines for air travel. [Accessed 2014 Dec. 14.] Available from: http://www.asma.org/publications/medicalpublications-for-airline-travel/medical-guidelines-for-airline-travel. 2. Rayman RB, Davenport ED, Dominguez-Mompell R, Gitlow S, Hastings JD, et al. Clinical aviation medicine, 5th ed. New York: Castle Connolly Graduate Medical Publishing, LLC; 2013. 3. Stroud MA, Belyavin AJ, Farmer EW, Sowood PJ. Physiological and psychological effects of 24-hour exposure to a low humidity environment. Farnborough (UK): Royal Air Force Institute of Aviation Medicine; May 1992. IAM report no 705.
AEROSPACE MEDICINE AND HUMAN PERFORMANCE Vol. 86, No. 5
May 2015
487
