On the basis of our data, we estimate that 44,000 in-flight medical emergencies occur worldwide each year. Medical emergencies during commercial airline travel, although rare when considered on a per-passenger basis, occur daily; traveling physicians and other health care providers are often called on to aid ill passengers. A basic knowledge of in-flight medical emergencies and awareness of the resources available can help them be effective volunteers. The emergency medical kit available on every commercial airliner regulated by the FAA is usually sufficient to initiate treatment for serious problems. Many airlines have an enhanced emergency medical kit, increasing treatment options (Table S3 in the Supplementary Appendix). Most in-flight medical emergencies are self-limiting or are effectively evaluated and treated without disruption of the planned route of flight. Serious illness is infrequent, and death is rare.

Although the FAA does not require consultation with a physician on the ground in the case of an in-flight emergency, airlines partner with specific health care delivery groups to provide consistent availability of medical expertise. Consulting physicians on the ground are able to communicate directly with flight crew members and on-board health care volunteers or through efficient relay processes involving the pilot. In our experience, passengers' symptoms can often be managed in collaboration with the flight attendants, who are well versed in the equipment that the airplanes carry and in operational procedures. When the need for evaluation or intervention exceeds their capabilities, flight attendants may seek health care professionals on the flight. Many airlines require consultation with a ground-based physician before the emergency medical kit is used. A collaborative approach to management of the medical problem should ensue. The health care provider in flight can make direct observations, and the consulting ground-based physician has familiarity with the environment, the available medical resources, knowledge of passenger health issues, and awareness of airline operational concerns. As a team, they provide the best possible care, given the constraints.

The risk of medical liability may be a concern for volunteer health care providers. The 1998 Aviation Medical Assistance Act includes a Good Samaritan provision,12 protecting passengers who offer medical assistance from liability, other than liability for gross negligence or willful misconduct.13 Although there is no legal obligation to intervene, we believe that physicians and other health care providers have a moral and professional obligation to act as Good Samaritans.

Table 3. Table 3. Recommendations for Traveling Physicians or Other Health Care Providers during In-Flight Medical Emergencies.

We suggest an algorithm for approaching the more common in-flight medical emergencies on the basis of our findings (Table 3). In our study, syncope, respiratory symptoms, nausea or vomiting, and cardiac symptoms were the most common in-flight emergencies, findings that are consistent with the results of prior studies.14,15 Although patients with syncope are often unresponsive and may initially have hypotension, in most cases, improvement occurs within 15 to 20 minutes, and further treatment is usually not required, other than oral or intravenous fluids. The partial pressure of oxygen is lower in a pressurized aircraft than at sea level, and supplemental oxygen can be helpful. Persistently altered mental status or factors that raise concern about time-sensitive conditions, such as myocardial infarction or stroke, should prompt consideration of landing the aircraft.

Potential cardiac symptoms account for a relatively large number of in-flight medical emergencies. Most can be managed with simple treatment after a focused history taking, until definitive care is available. Aspirin, nitrates, and oxygen are available in the emergency medical kit. Patients with angina or atypical chest pain can be treated and transferred to an ambulance on landing. In cases in which myocardial infarction or acute dysrhythmia is suspected, monitoring with an AED may aid in diagnosis and decisions about disposition. Serious nonarrest cardiac events resulting in hospital admission are rare; of the 920 nonarrest cardiac cases, none resulted in death.

Obstetrical symptoms were rare causes of in-flight medical emergencies, a finding that supports existing recommendations that air travel is safe up to the 36th week of gestation.16 The majority of cases of obstetrical or gynecologic symptoms (60.7%) occurred in pregnant women at less than 24 weeks of gestation. Only three cases involving pregnant women in labor beyond 24 weeks resulted in diversion.

In-flight cardiac arrest can be managed with an AED and epinephrine, which is stocked in the emergency medical kit. The rate of survival after cardiac arrest on a commercial airliner ranges from 14 to 55%, with the higher rates among patients with ventricular fibrillation.17,18 We found that in 42.1% of cases of cardiac arrest, the flight was not diverted. These cases included arrests that occurred at a time when immediate diversion was not feasible (e.g., while the airplane was crossing the ocean), and arrests that occurred when the airplane was close to the intended destination and diversion would not have been beneficial to the patient. The death rate among all patients with in-flight medical emergencies was 0.3%, which is consistent with previously reported rates of 0.3 to 1.3%.1-3,9

Common challenges to providing medical care aboard an aircraft include limited space and equipment. In unfamiliar settings, physicians and others may rely on what they know best, including making specific diagnoses on the basis of their areas of expertise. Physicians and other health care providers may be called on by the crew for more serious cases, which may help explain the higher rates of diversion and hospitalization when health care professionals provide on-board assistance.

Diversion of a commercial airliner to an unscheduled destination for an ill passenger requires consideration of both medical and operational issues. The potential medical benefit should be assessed on the basis of the condition and its time sensitivity, the ability to stabilize the patient's condition with available supplies, and the likely time savings with consideration of the time needed to land and the proximity of medical resources to specific airports. Immediate operational factors that may contribute to variability in airline practices include weather, fuel load and the potential need to drop fuel before landing, the availability of specific aircraft services at airports, and air-traffic control.

Our study is limited by its retrospective nature, with only in-flight medical emergencies that prompted calls to our communications center included in the analysis. Although all flight crews are instructed to use this consultation service for any in-flight medical emergency, there are events that occur without notification of the communications center. The medical categories we used were based on descriptions of the passenger's primary symptom, not on diagnoses. The data obtained as part of these consultations were limited by the use of radio or satellite-telephone transmission, communications among multiple people, and the collection of follow-up data from facilities located across the world. Follow-up data were not available for one airline, although the medical problems encountered by that airline were similar to the problems encountered by the other airlines. Differences among airlines in the likelihood of diversion, EMS transport, and hospital admission warrant further study.

On the basis of our findings, we believe that airline passengers who are health care professionals should be aware of their potential role as volunteer responders to in-flight medical emergencies. We also advocate for systematic tracking of all in-flight medical emergencies, including subsequent hospital care and other outcomes, to better guide interventions in this sequestered population.