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Thomas McCabe describes a case of delirium apparently precipitated by flying. This is not unusual. Most liaison psychiatrists, especially old age liaison psychiatrists, will have seen several such cases and many of them after shorter flights. I reviewed the evidence for this in 2002 (1) and again in 2012 (2) and presented some ideas about how to proceed.
Planes ascend to and descend from 30,000 – 40,000 feet above sea level in 20 minutes; in-flight cabin environments are artificially controlled, except for ambient radiation which is higher at these altitudes. The controlled cabin pressures are equivalent to 6,000 – 8,000 feet above sea level. At these altitudes, there is a reduction of 20 – 26% available oxygen resulting in haemoxyhaemoglobin saturations 83 – 85% of normal. In fit people this can cause tachycardia, tachypnoea, headaches, dizziness, impaired coordination, fatigue and confusion. Reduced air pressure can also cause peripheral oedema and expansion of any air-filled spaces such as bowels, sinuses and middle ears (Boyle’s law).
Air humidity is reduced at altitude. The ‘comfort zone’ for humidity is 50 – 65%. A centrally heated room has about 25% humidity and air cabin humidity is 1 – 20%. This can cause dehydration, hypovolaemia and reduced peripheral circulation.
Most research on passenger health has been done on fit young airmen, but the effect on the physiology of older or unw...
Most research on passenger health has been done on fit young airmen, but the effect on the physiology of older or unwell people, or those with evidence of cerebrovascular disease, is unclear.
The Warsaw Convention (1929) states that airlines are not responsible for their customers’ health; the fact that passengers are responsible for their own health may limit the industry’s motivation to explore this further. The British Medical Association have published a review of the impact of flying on passengers’ physical health (3).
For some years I have advised my patients with dementia, especially those with significant vascular aetiology, to avoid flying if possible. If flying is essential, I advise that they sit near the front of the plane (higher oxygen saturation), drink plenty of non-alcoholic fluids and move as much as possible during the flight.
I agree with many of Dr McCabe’s recommendations. The most important next step is research into the prevalence of post-flight confusion, its prognosis and risk factors. This would not be difficult to do, though may be controversial. For instance, people over the age of 65 embarking on flights of more than 4 hours could be asked to complete cognitive tests before departure, within a week of return and a few months after return. Any signs of confusion would indicate further investigations. It may be that those who experience sun-downing or psychotic symptoms are more at risk, but this needs researching. Only by identifying the extent and associated risk factors of post-flight confusion can good advice be given to patients, travellers and the travel industry. More knowledge would not only give clues to aetiology but also inform risk reduction.
1 G.Rands (2002) Fear of Flying reviewed. An example of evidence based Old Age Psychiatry, Psych. Bulletin, 26. 188–190
2 Gianetta Rands (2011) Have we gone too far in translating ideas from aviation to patient safety? letter BMJ 2011 342:c7309; doi:10.1136/bmj.c7309
3 The Impact of Flying on Passenger Health; a guide for healthcare professionals BMA Board of Science and Education, BMA (2004). www.bma.org.uk
I read with interest the case report of delirium being associated with long-haul air travel. A plethora of causes were investigated to ascertain the aetiology of the delirium; however I note that the authors did not consider the impact of crossing multiple time zones and resulting disruption of the circadian rhythm. There are multiple reasons why circadian disruption might contribute to a delirium: excessive tiredness, change in sleep-wake cycle, and disorientation in time, to name but a few. Sleep disturbance is a well-recognised clinical feature in individuals with both delirium and dementia. From my personal experience of crossing multiple time zones on a long-haul flight, the effects can be unsettling to say the least. One can only imagine the stress this could place upon a vulnerable brain with a predisposition to acute or chronic cognitive deficits.
Future research in the areas of sleep, dementia, and delirium might provide more guidance for health professionals advising patients about long-haul air travel.
Vol 41 Issue 1
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