In-flight emergency: the volunteer doctor and the diversion

Two hours after takeoff, on a night flight over the ocean, the crew asks over the public address system whether there is any healthcare professional on board. A doctor stands up and finds, near the aisle, a man in his early sixties, pale and sweaty, who says he blacked out for a few seconds on his way back from the bathroom. Now he is awake, talking and wants to return to his seat. The flight attendant asks whether the plane needs to land. The scene is fictional and was written for teaching. This text uses that setting as a clinical reasoning scenario: what usually happens on board, what cabin altitude changes, what resources the doctor can count on and how the decision to divert the flight is made together.

The text avoids being a protocol. Each airline has its own procedures, and the volunteer's legal responsibility varies by country. The interest here is the reasoning: how to assess someone in a cramped, noisy environment with few instruments, and how to turn that assessment into a useful recommendation for whoever decides the plane's course. If you play the case of the day on NEXO, you will recognize the move: few clues, little time and a decision that has to be good enough.

Key points

• Medical emergencies on commercial flights are frequent, and syncope or near syncope is the most common complaint in the large published series.
• The cabin is pressurized as if the plane were at a moderate altitude, which lowers the oxygen saturation of healthy passengers and can destabilize those who already have heart or lung disease.
• The volunteer doctor works with the on-board kit, with the crew and, usually, with a ground medical service that advises by radio or satellite.
• The decision to divert the flight belongs to the captain, made with the medical recommendation, ground support and operational factors such as distance, weather and airport resources.
• The conditions with the highest chance of hospitalization after landing include suspected stroke, respiratory symptoms and cardiac symptoms.

Why the airplane cabin is a clinical reasoning scenario

Peterson and colleagues analyzed 11,920 medical emergency calls made to a ground support center by five airlines and estimated one emergency every 604 flights (Peterson and colleagues, 2013). With millions of flights per year, that means many healthcare professionals will hear, at some point, the call for help over the public address system.

The setting brings together almost every difficulty of clinical reasoning in an extreme environment. The space is small, the light is poor, noise gets in the way of auscultation and the patient often speaks another language. The history may come from a frightened companion. The available tests are few. And the final decision, land or continue, has consequences for hundreds of people. At the same time, the clinical problem is usually common: fainting, shortness of breath, chest pain, nausea. The challenge is to apply familiar reasoning under conditions that do not help.

What the volunteer brings to the scene

Martin-Gill and colleagues reviewed in-flight emergency care and describe the role of the volunteer professional: assess the passenger, use the on-board kit, communicate the findings to the crew and work together with the ground medical service, which guides care and helps with the decision about diversion (Martin-Gill and colleagues, 2018). Cocks and Liew point out that the volunteer does not have to act alone, because the crew and other sources of help are available, and does not have to work alone (Cocks and Liew, 2007).

For clinical reasoning, this has a practical consequence. The volunteer does not need to reach a definitive diagnosis. They need to answer simpler questions: is the condition serious now, can it worsen in the coming hours and what changes if the plane lands earlier? These questions recall those of triage and of the teleconsultation, where the decision depends more on risk than on the exact name of the disease.

An environment that changes physiology

The cabin is pressurized, but not to sea level. Martin-Gill and colleagues note that cabin pressure on a cruise flight usually corresponds to an altitude between five thousand and eight thousand feet, which lowers the partial pressure of oxygen in the inspired air (Martin-Gill and colleagues, 2018). Humphreys and colleagues measured the saturation of healthy passengers on commercial flights and found a mean of 97 on the ground and 93 at cruise, with 54 in every 100 passengers reaching 94 or less during the flight (Humphreys and colleagues, 2005).

For a healthy person, this drop goes unnoticed. For someone already living at the limit, with chronic lung disease, heart failure or anemia, it can be the difference between staying well and decompensating. Gas in the closed spaces of the body also expands as pressure falls, which matters in someone who had recent surgery or has an undiagnosed pneumothorax. The World Health Organization keeps a page dedicated to health in travel, with general guidance for those who are going to fly (WHO, health and travel).

What usually happens on board

The baseline rate of complaints on board is the starting point of the reasoning. In the series by Peterson and colleagues, syncope or near syncope accounted for 37 in every 100 calls, respiratory symptoms for 12 in every 100 and nausea or vomiting for about 10 in every 100 (Peterson and colleagues, 2013). Sand and colleagues, in a European series of 10,189 attendances, found syncope or fainting in about 54 in every 100 calls (Sand and colleagues, 2009).

The table below organizes the most common complaints in a didactic way. It simplifies a broad field and should be read together with the sources cited in the text.

Complaint on board	Frequent causes	What calls for greater attention
Fainting or near fainting	Vasovagal reflex, dehydration, alcohol, long periods seated	Chest pain, palpitation, fainting without warning, persistent shortness of breath
Shortness of breath	Asthma, chronic lung disease, anxiety, relative hypoxia of the cabin	Saturation that does not improve with oxygen, chest pain, swollen leg
Chest pain	Reflux, muscle pain, anxiety	Squeezing pain, cold sweat, radiation, history of coronary disease
Nausea and vomiting	Motion sickness, food, gastroenteritis	Intense abdominal pain, signs of significant dehydration
Neurological symptoms	Hypoglycemia, migraine, syncope	Weakness on one side, altered speech, crooked face
Seizure	Known epilepsy, sleep deprivation, alcohol	First seizure, prolonged seizure, no recovery of consciousness

What happens after landing

Peterson and colleagues also followed the outcome. A doctor on board helped in about 48 in every 100 calls, the plane diverted in about 7 in every 100, about 26 in every 100 passengers were taken to hospital, about 9 in every 100 were admitted and deaths stayed below 1 in every 100 (Peterson and colleagues, 2013). The authors identified that suspected stroke, respiratory symptoms and cardiac symptoms were among the conditions with the highest chance of admission (Peterson and colleagues, 2013).

These numbers help calibrate the decision. Most emergencies on board end well, with the passenger recovered before landing. A small share needs hospital care urgently. The volunteer's job is to identify which group the passenger in front of them is in.

Syncope on board: the most common problem

Let us return to the passenger in the scene. He passed out for a few seconds on the way back from the bathroom, is pale and sweaty, and now talks normally. By the baseline rate, the most likely explanation is a reflex faint: a long time seated, little water, perhaps alcohol, standing up quickly in an environment with less oxygen. This hypothesis is reasonable and, most of the time, correct.

Reasoning, however, does not stop at the most likely hypothesis. The next question is: what would be serious and needs to be ruled out? In fainting, serious causes include arrhythmia, heart attack, pulmonary embolism, internal bleeding and stroke. Some clues help separate the groups: fainting during exertion or without any warning, chest pain, palpitations before the event, persistent shortness of breath, a history of heart disease and older age raise concern.

What can be examined

With the onboard kit, the assessment usually includes pulse, blood pressure, respiratory rate, skin color, level of consciousness and, when available, blood glucose and pulse oximetry. Martin-Gill and colleagues describe that the kit contents vary according to each country's regulations, and that some flights also carry an automated external defibrillator (Martin-Gill and colleagues, 2018). Gendreau and DeJohn report that the United States aviation authority has required an emergency medical kit since 1986 on commercial aircraft with more than 30 seats and began requiring a defibrillator from 2004 (Gendreau and DeJohn, 2002).

Laying the passenger down, if there is space, and raising the legs usually helps in reflex fainting and also serves as a test: those who improve quickly and stay improved have a different profile from those who remain pale, with an irregular pulse or low blood pressure.

The question that changes the decision

For the crew, what matters is knowing whether the passenger needs a hospital before the destination. For the volunteer, this translates into two questions: is the condition stable and improving, and is there any sign of a serious cause? If the answer is yes to the first and no to the second, continuing the journey with observation is usually reasonable. If there are warning signs, the recommendation to land gains weight. The post about diagnostic uncertainty discusses how to decide when the available information is incomplete.

Respiratory and cardiac: when cabin altitude matters

Peterson and colleagues showed that respiratory and cardiac symptoms are among those that most lead to hospitalization after landing (Peterson and colleagues, 2013). In these cases, the relative hypoxia of the cabin can be part of the problem and part of the solution.

Shortness of breath that does not improve

A passenger with chronic lung disease may reach their limit at cruise, even without any new event. Another may have asthma triggered by stress or dry air. A third may have pulmonary embolism after hours seated. The oxygen available on board helps the first group and buys time to think about the third. The response to oxygen is itself a clue: those who improve quickly and stay improved have a different profile from those who remain short of breath even with oxygen.

Chest pain at altitude

In chest pain, the central question is whether it could be acute coronary syndrome. The history, age, risk factors and the patient's appearance weigh more than any test available on board. The reduced oxygen in the cabin can worsen an ischemia that already existed. Oxygen, rest and the medication available in the kit are the tools, and the decision about diversion enters the conversation early, with ground support when suspicion is high.

The onboard kit and what it allows

Martin-Gill and colleagues describe that aviation authorities define a minimum content for the onboard medical kit, which includes instruments to measure vital signs, medications commonly used in emergencies and material for venous access, with variation between countries (Martin-Gill and colleagues, 2018). Knowing the kit before you need it helps organize reasoning: what can be measured defines which hypotheses can be tested.

The kit usually allows you to:

• measure blood pressure and heart rate;
• auscultate the heart and lungs, when the noise allows;
• provide supplemental oxygen;
• administer medications commonly used in emergencies, according to what is available;
• use the automated external defibrillator when the plane carries one;
• measure blood glucose and oxygen saturation, when there are devices for this.

What is missing

What is missing also guides the reasoning. On board, there are no complete laboratory tests, imaging or twelve-lead electrocardiogram on most flights. This means that some serious hypotheses cannot be confirmed or safely ruled out before landing. When a serious hypothesis remains plausible and there is no way to test it, that is an argument in favor of landing earlier.

Attention to the passenger's own medication

Many passengers carry their medicines in their hand luggage. Asking about them and, when possible, looking at the packaging brings valuable information: use of anticoagulant, insulin, nitrate, bronchodilator or heart medication changes the differential and sometimes offers an immediate treatment that the on-board kit does not have.

Medical support on the ground

Many airlines contract medical services that respond by radio or satellite during the flight. Martin-Gill and colleagues describe that the volunteer passes the findings to the crew, who communicate with the ground support, and that this service guides care and takes part in the recommendation about diversion (Martin-Gill and colleagues, 2018).

How to hand over the case

Communication with ground support has something of a teleconsultation and something of a shift handover. A simple structure helps:

1. Who the passenger is: age, sex and known diseases.
2. What happened: the complaint, when it started and how it evolved.
3. What was found: vital signs, examination and response to what has already been done.
4. What worries: the serious hypothesis that has not yet been ruled out.
5. What is proposed: observe, treat or recommend landing.

This structure helps the person on the other side understand the risk in a few seconds. It also forces the volunteer to organize their own reasoning, which is already a form of diagnostic pause.

Sharing the decision

Cocks and Liew point out that the volunteer should not feel alone in the decision, because it is shared with the crew and with ground support, and that the medico-legal risk for those who help in good faith is small (Cocks and Liew, 2007). Martin-Gill and colleagues recall that the volunteer's legal protection varies from country to country (Martin-Gill and colleagues, 2018). Legal aspects are outside the scope of this text, and those who travel often can seek guidance from the professional council of their own country.

The decision to divert the flight

Diverting an aircraft is an operational decision with a medical component. Martin-Gill and colleagues report diversion in about 4 in every 100 emergencies in the reviewed literature (Martin-Gill and colleagues, 2018), and Sand and colleagues found diversion in about 3 in every one hundred cases in the European series (Sand and colleagues, 2009).

What goes into the decision

The medical recommendation is one part of the decision. Apart from some safety situations, the decision to divert belongs to the captain (SKYbrary, Diversion). Nable and colleagues describe that this decision rests solely with the captain and that it takes into account fuel, operating costs, the aircraft's ability to land at the nearest airport and the medical resources available there (Nable and colleagues, 2015). Gendreau and DeJohn add that the ground service physician can advise on diversion and on possible landing sites (Gendreau and DeJohn, 2002). The captain also considers the distance and time to the alternate airport and to the destination, the medical resources available near each airport, the weather, the fuel, the aircraft's landing weight, the safety of the other passengers and the guidance of the ground medical service.

For the volunteer, the useful question is: what does this passenger gain from a hospital two or three hours earlier? In suspected stroke, heart attack or severe bleeding, the gain can be large. In a reflex faint that has already improved, the gain is usually small.

The mistake of thinking only about landing

A common mistake is to turn the decision into a yes or no. In practice, there are intermediate options: continue with observation and reassess every half hour, prepare a medical team for disembarkation, agree with ground support on a worsening criterion that leads to diversion. Defining this criterion in advance, for example new loss of consciousness or a drop in blood pressure, gives direction to the observation. The post on clinical decision-making helps to think of approaches as choices with risks and benefits.

Common biases in on-board care

Croskerry described how cognitive errors lead to diagnostic errors and proposed strategies to reduce them (Croskerry, 2003). Graber and colleagues showed that cognitive factors, such as premature closure, are present in a good part of diagnostic errors in internal medicine (Graber and colleagues, 2005). The airplane cabin favors some of these biases.

The "it was just a fainting spell"

Since reflex syncope is the most common explanation, it tends to arrive first and to stay. When the passenger wakes up and talks, the feeling of relief favors premature closure. The antidote is to ask what would need to be present to change your mind: chest pain, palpitations, fainting without warning, cardiac history. The post about heuristics in clinical reasoning shows how useful shortcuts can mislead.

The pressure of the context

The volunteer may feel pressured not to disrupt the trip of hundreds of people or, on the contrary, to recommend landing out of insecurity. Both movements are understandable, and the best remedy for both is to return to the central questions: what is the risk now, what is the risk in the coming hours and what changes with landing. Shared decision-making with ground support helps reduce the individual burden.

Anchoring on the companion's account

The first story, often told by a frightened companion, can anchor the reasoning. Also listening to the passenger, when possible, and confirming the sequence of events helps prevent a wrong detail from guiding the whole assessment.

How NEXO helps train this reasoning

To use the case of the day as training, try three habits. Before each guess, write down the most likely hypothesis and the serious hypothesis that still needs to be ruled out. When a clue seems to solve the case, ask what it leaves unexplained. After the result, note which clue would have changed your decision earlier.

Three exercises with cases

Think like a volunteer. Imagine you only have pulse, blood pressure, oxygen saturation and the history. Which hypotheses can you separate with that?

Hand off the case. Summarize the case in five lines, as if you were talking to ground support, and see whether the serious hypothesis appears in the summary.

Define the criterion. For each case, write the finding that would make you recommend an immediate landing.

The post about simulation of care shows why rehearsing rare situations helps you act better when they happen.

The limits on using the game are described on the NEXO Economy page. If you research the teaching of clinical reasoning, the page for Researcher explains how to get in touch. Professionals who write or review cases find information in Curator and in Creators, and institutions can learn about the proposal on the partnerships page.

Frequently asked questions

What is the most common medical emergency on flights?

In the large published series, syncope or near-syncope is the most frequent complaint. Gastrointestinal and respiratory symptoms come next, in an order that varies between series.

Why do healthy passengers have lower oxygen saturation in flight?

Because the cabin is pressurized as if it were at a moderate altitude, which reduces the oxygen pressure in the air breathed. In healthy people, this drop is usually well tolerated.

What does the volunteer doctor find in the onboard kit?

Generally, instruments to measure vital signs, oxygen, medications commonly used in emergencies and material for venous access. The contents vary according to each country's regulations.

Who decides whether the plane will divert?

The captain decides, based on the volunteer's recommendation, on guidance from the ground medical service and on operational factors such as distance, weather and airport resources.

Which conditions weigh most in favor of landing?

Suspected stroke, chest pain with a profile of coronary disease, shortness of breath that persists even with oxygen, significant bleeding and loss of consciousness that repeats or that does not recover.

Does the volunteer need to close the diagnosis?

They need to estimate the risk and answer whether the passenger is stable, whether they may get worse and what they gain from reaching a hospital sooner. These answers guide the shared decision.

Take-home messages

• I considered the base rate of complaints on board before closing the hypothesis.
• I wrote next to the most likely hypothesis the serious hypothesis to rule out.
• I remembered that the cabin reduces oxygenation and can decompensate prior diseases.
• I used the response to oxygen and rest as a clue.
• I handed the case to ground support with a clear structure.
• I defined with the team a worsening criterion that leads to diversion.

Want to practice the reasoning with progressive clues? Play the case of the day.

References

1. Cocks R, Liew M. Commercial aviation in-flight emergencies and the physician. Emerg Med Australas. 2007. PMID 17305654.
2. Croskerry P. The importance of cognitive errors in diagnosis and strategies to minimize them. Acad Med. 2003. PMID 12915363.
3. Gendreau MA, DeJohn C. Responding to medical events during commercial airline flights. N Engl J Med. 2002. PMID 11932475.
4. Graber ML, Franklin N, Gordon R. Diagnostic error in internal medicine. Arch Intern Med. 2005. PMID 16009864.
5. Humphreys S, Deyermond R, Bali I, et al. The effect of high altitude commercial air travel on oxygen saturation. Anaesthesia. 2005. PMID 15819766.
6. Martin-Gill C, Doyle TJ, Yealy DM. In-Flight Medical Emergencies: A Review. JAMA. 2018. PMID 30575886.
7. Nable JV, Tupe CL, Gehle BD, Brady WJ. In-Flight Medical Emergencies during Commercial Travel. N Engl J Med. 2015. PMID 26332548.
8. Peterson DC, Martin-Gill C, Guyette FX, et al. Outcomes of medical emergencies on commercial airline flights. N Engl J Med. 2013. PMID 23718164.
9. Sand M, Bechara FG, Sand D, Mann B. Surgical and medical emergencies on board European aircraft: a retrospective study of 10189 cases. Crit Care. 2009. PMID 19154581.
10. SKYbrary Aviation Safety. Diversion. skybrary.aero.
11. World Health Organization. Travel and health. who.int.