Readers familiar with the comedy film Airplane! (1980) might recall a scene in which an air steward asks passengers if there is a doctor aboard the aircraft. An elderly woman remarks that she thinks the man sitting next to her is a doctor. Cut to Leslie Nielsen complete with stethoscope around his neck and medical bag in tow, as he confirms that he is indeed a doctor and rises to assist multiple passengers who appear to have come down with food poisoning. It is a hilariously clichéd enactment of a situation that would fill many real doctors with terror.

So, with summer approaching and your holiday flights booked, what will you do if called upon to assist with an on-board emergency? Thankfully, Martin-Gill, Doyle and Yealy recently published an informative systematic review in the Journal of the American Medical Association.¹ According to the authors, the prevalence of in-flight medical emergencies (IMEs) is one in 604 flights (or 24-130 per million passengers).  As such, they estimate a possible 260-1,420 IMEs daily worldwide. Seemingly the most common variety of IME is syncope or near-syncope, which accounts for almost one-third. Gastrointestinal, respiratory and cardiovascular illness represent 15%, 10% and 7% respectively, while in-flight cardiac arrest is thankfully rare (0.2% of IMEs).

Why might it happen at all? In terms of pathophysiology, the authors cite a number of factors. With cabin air pressure reduced to 11-12 psi (the equivalent of that at an altitude of 5,000-8,000 feet), bodily enclosed gas-filled spaces (sinuses, middle ear and so forth) will experience a gas-volume expansion of up to 30%, potentially leading to discomfort. Cabin oxygen pressure is also lower, resulting in mild hypoxia (with mean arterial pressure reduced from 97% to 93%), which can exacerbate existing pulmonary conditions. Prolonged sitting and hypoxia increase the risk of deep venous thrombosis, while recycling of air can expose passengers to allergens and communicable disease.

So, having barely ordered your toasted sandwich and perhaps a tiny can of Heineken as you flick through the in-flight magazine, the air steward calls on you for assistance. What do you do? Firstly understand that you will not have to act alone. Airlines have ground-based medical support (usually outsourced) with trained medical personnel who provide recommendations when IMEs occur. Airlines only seek suitably-qualified passenger volunteers to help gather information, assess a sick or injured passenger, aid communication, administer medication or perform procedures. Important decisions are ultimately left to the captain while, according to the authors, flights are diverted in only 4.4% of IMEs. Data suggest that around 50% and 25% of IMEs involve a volunteer doctor or nurse respectively, but the authors advise that such volunteers should first assess whether they are capable of providing help and should certainly not be under the influence of alcohol or drugs. If there is more than one volunteer available, a collegial conversation will likely yield the most suitable person to assist.  

The paper provides specific advice for common IMEs. But will you be sued if it all goes wrong? Reference is made to the Aviation Medical Assistance Act in the US, which protects volunteering passengers from legal action unless they are grossly negligent. The authors also stress that seeking compensation (upgraded seats, mileage points etc) may invalidate this protection. The Warsaw, Montreal and Tokyo Conventions likely apply universally; moreover, in some jurisdictions (such as Australia), there is a legal duty to respond to an IME. This is worth bearing in mind when choosing an airline.   

Reference

1. Martin-Gill C, Doyle TJ, Yealy DM. In-flight medical emergencies: a review. JAMA  2018, Dec 25; 320(24):2580-90. doi: 10.1001/jama.2018.19842