The potential risk to health from travelling by air are many and varied. On a recent trip from Stansted the aircraft I was flying in hit some clear air turbulence and dropped like a stone. A passenger in the row in front of ours was scalded by hot tea and he required first aid treatment as a result.
While an incident such as this is exceptional, medical emergencies in the air are on the increase. An analysis of the flight movements at Shannon Airport for November 1999 showed a total of five unscheduled landings at the airport to facilitate the treatment of a sick passenger. These planes were flying to and from North America and Europe when the medical condition of a passenger required a premature landing.
Virgin Atlantic Airways, the long-haul carrier, recorded a total of 24 inflight medical emergencies in 1998. These included four cardiac arrests, six suspected heart attacks, two miscarriages, five strokes and one passenger with acute abdominal pain. In eight of the 24 emergencies, the plane had to divert to an alternative airport to access emergency treatment.
Not surprisingly, Virgin Atlantic made a decision in 1990 to place semi-automated defibrillators on board its aircraft to deliver electrical current to reverse a sudden cardiac arrest. These automatic external defibrillators (AEDs) supply an electric shock to the heart, after the machine has analysed the presence of a rhythm disorder called ventricular fibrillation. Research has shown that the interval between the onset of ventricular fibrillation and the delivery of the first shock is the main determinant of a successful outcome. Survival falls by approximately 10 per cent for every minute after collapse for patients with this common complication of cardiac arrest.
Virgin Atlantic has had some success with the AED - one person is still alive today after surviving four cardiac arrests on a flight to Miami in November 1997.
More than 10 years later, Aer Lingus has announced plans to instal AEDs on its longhaul Airbus A330s. The airline is currently in discussion with the Irish Heart Foundation with a view to organising training for cabin crew. This should see the planned introduction of defibrillators in April by the national airline.
Modern aircraft fly at an altitude of 33,000-37,000 feet. At this height and air pressure, the ability of the blood to carry oxygen falls by up to 10 per cent. This could be a problem if you have angina (narrowing of the coronary arteries), heart failure or a low blood count. People with obstructive airways disease may develop dangerously low levels of oxygen in the blood stream.
If you have any of these conditions and are wondering if you are fit to travel, the following is a good rule of thumb. An ability to walk 50 metres on the flat or climb 12 steps of stairs without becoming breathless or developing chest pain suggests you are fit to fly. Flying involves travelling in a confined and sometimes cramped space. With longhaul flights lasting up to 14 hours, a completely new medical condition has been identified. Called economy class syndrome, it involves the formation of blood clots in the deep veins of the legs. These can travel to the lung, causing pulmonary embolism, a potentially fatal condition.
Narrow seat pitches mean that some passengers' legs can be trapped or their thighs compressed by the seat edge. This can lead to clot accumulation, as the blood flow becomes sluggish. When combined with some conditions that increase the natural tendency of the blood to clot (being pregnant, overweight or taking the contraceptive pill for example) long periods of sitting can lead to a problem.
It is important to take preventive action. The ideal situation is to walk around the aircraft every half hour to stretch tense muscles. If this is not possible, occasionally massaging and contracting your leg muscles will help. Placing hand luggage under your feet will also ease any compression of your thighs against the seat edge. Drink plenty of water, which will help to prevent excessive stickiness in the blood. Try to avoid taking sedatives during the flight as these will encourage heavy sleep and a consequent lack of movement.
There are three cardinal rules for good health while flying: walk around at regular intervals; abstain from alcohol but drink plenty of fluids; keep taking your prescribed medication throughout the flight.
Don't fly if: you are more than 36 weeks pregnant; you are breathless at rest; you have suffered a heart attack in the past four weeks; you suffer from severe anaemia (blood count < 8 gms/dl); You have had abdominal surgery in the past 10 days. If you are in any doubt about your fitness to fly, talk to your family doctor.
Dr Muiris Houston can be contacted by email at mhouston@irish-times.ie