Management of In-Flight Medical Emergencies
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Martin-Gill C, Doyle TJ, Yealy DM. In-Flight Medical Emergencies: A Review. JAMA. 2018;320(24):2580–2590. doi:10.1001/jama.2018.19842
In-flight medical emergencies (IMEs) are common and occur in a complex environment with limited medical resources. Health care personnel are often asked to assist affected passengers and the flight team, and many have limited experience in this environment.
In-flight medical emergencies are estimated to occur in approximately 1 per 604 flights, or 24 to 130 IMEs per 1 million passengers. These events happen in a unique environment, with airplane cabin pressurization equivalent to an altitude of 5000 to 8000 ft during flight, exposing patients to a low partial pressure of oxygen and low humidity. Minimum requirements for emergency medical kit equipment in the United States include an automated external defibrillator; equipment to obtain a basic assessment, hemorrhage control, and initiation of an intravenous line; and medications to treat basic conditions. Other countries have different minimum medical kit standards, and individual airlines have expanded the contents of their medical kit. The most common IMEs involve syncope or near-syncope (32.7%) and gastrointestinal (14.8%), respiratory (10.1%), and cardiovascular (7.0%) symptoms. Diversion of the aircraft from landing at the scheduled destination to a different airport because of a medical emergency occurs in an estimated 4.4% (95% CI, 4.3%-4.6%) of IMEs. Protections for medical volunteers who respond to IMEs in the United States include a Good Samaritan provision of the Aviation Medical Assistance Act and components of the Montreal Convention, although the duty to respond and legal protections vary across countries. Medical volunteers should identify their background and skills, perform an assessment, and report findings to ground-based medical support personnel through the flight crew. Ground-based recommendations ultimately guide interventions on board.
Conclusions and Relevance
In-flight medical emergencies most commonly involve near-syncope and gastrointestinal, respiratory, and cardiovascular symptoms. Health care professionals can assist during these emergencies as part of a collaborative team involving the flight crew and ground-based physicians.
In-flight medical emergencies (IMEs) are unique events for which traveling physicians, nurses, and other health care professionals may render medical assistance. Cruising at 35 000 ft with limited medical equipment, often hours away from the closest medical facility, creates an unfamiliar care challenge for many health care professionals. This clinical review focuses on IME data and offers guidance to assist medical professionals who may encounter these events using both literature and the authors’ insights providing airline care guidance for IMEs.
A literature search was conducted in MEDLINE using PubMed for English-only articles published between January 1, 1990, and June 2, 2018, using the terms air emergency, air emergencies, air passenger, air travel, aircraft, airline, aviation, commercial air, flight, and fitness to fly (n = 14 842). Scanning the titles to identify appropriateness and searching bibliographies yielded the final list of relevant articles (n = 765). Each article was assessed for completeness of data reporting and importance to management and prevention of IMEs. Based on this assessment, a total of 317 articles were included in the review. Frequency data were extracted and means and 95% confidence intervals were calculated when appropriate.
The estimated prevalence of IMEs is 1 in 604 flights based on a review of 11 920 requested ground consultations from 5 large domestic and international airlines from 2008 to 2010.1 This is likely an underrepresentation of all IMEs because many minor incidents do not result in consultations. Other IME frequency estimates from individual airlines with data from 2009 to 2013 ranged from 24 to 130 IMEs per 1 million passengers.2,3 Given that 4 billion commercial airline passengers travel worldwide annually,4 it is possible that 260 to 1420 IMEs occur daily worldwide.
A total of 14 articles described the relative frequency of medical conditions comprising IMEs aboard commercial aircraft (Table 1).1-3,5-15Quiz Ref ID The aggregate frequency of medical conditions among 49 100 IMEs showed that syncope or near-syncope was the most common IME (32.7%); other common condition categories included those with gastrointestinal (14.8%), respiratory (10.1%), and cardiovascular (7.0%) symptoms. In-flight cardiac arrest was rare (0.2% of IMEs).
Diversion refers to altering a flight destination for a medical emergency; based on 14 publications reporting 56 599 IMEs (Table 2), diversion occurred in 2515 flights with IMEs (4.4%; 95% CI, 4.3%-4.6%).1-3,5-10,13-17
Quiz Ref IDCommercial aircraft fly at a cruising altitude (during level flight) of 30 000 to 40 000 ft, and passenger cabins are pressurized to 12 psi to 11 psi, which is equivalent to being at an altitude of 5000 to 8000 ft.18-22 This pressurization leads to expansion of closed gas-containing spaces in the body (eg, sinuses and middle ear) and nonphysiological gas collections (eg, pneumothorax or following gastrointestinal, ocular, or intracranial surgery).23 At 8000 ft of altitude or equivalent, the volume of gas in an enclosed space increases by approximately 30%24; altitude changes commonly trigger discomfort in patients, especially those with existing upper respiratory tract inflammation or infection, including sinusitis or otitis media.
The aircraft cabin has a lower partial pressure of oxygen at altitude, with resultant mild hypoxia in healthy passengers (decreasing mean arterial oxygen saturation from 97% to 93%). This effect can be more pronounced or symptomatic in passengers with existing pulmonary conditions.23-26 Passengers with hypoxia or respiratory insufficiency at baseline may benefit from supplemental oxygen at cruising altitude27-29; alternatively, the baseline flow of oxygen may need to be increased for the duration of a flight. Use of a portable oxygen concentrator during flight needs approval by the airline, a physician’s certification of need, and sufficient battery life, all typically coordinated at least 48 hours prior to the flight.30-32
Quiz Ref IDProlonged sitting and hypoxia may trigger decreased venous flow, systemic inflammation, and platelet activation, which explains the association between air travel and venous thromboembolism,33,34 although controversy exists regarding the risk compared with the general population.34-38 Symptoms of deep venous thrombosis or pulmonary embolism most commonly present hours to days after completing air travel39 but can occur on flights of long duration or during multiple flights in succession.40,41 The risk of lower limb venous thrombosis in high-risk passengers may be up to 5% per flight,41 and symptomless venous thromboembolism may occur in up to 10% of passengers on flights of long duration (ie, >4 hours).42
Quiz Ref IDCabin air, drawn from an outside dry environment at altitude and pressurized and dehumidified by cycling through the engine compartment, may contribute to dehydration among passengers.21,24,43 Recycling of air may also expose passengers to potential allergens, even when the source of allergens is several rows away from a passenger. Although the enclosed and limited-space environment of aircraft raises concern for transmission of communicable diseases,44,45 preexisting exposure is a more common infectious source.
The Federal Aviation Administration (FAA) has minimum requirements for contents of an emergency medical kit aboard US airlines (Table 3).46 Non-US airlines have different minimum requirements,6,47 and individual airlines vary widely in the contents of their emergency medical kits.23 The FAA requires automated external defibrillators on all airplanes with “a maximum payload capacity of more than 7,500 pounds and with at least one flight attendant,”46 but automated external defibrillators are not currently mandated for European airlines.48,49 The FAA-mandated medical kit contains protective gloves and equipment for a basic medical assessment, hemorrhage control, and initiation of an intravenous line (Table 3). The FAA-mandated medical kit contents also include medications to treat mild pain, allergic reactions, bronchoconstriction, hypoglycemia, dehydration, and some cardiac conditions. Common enhancements to the medical kit include a glucometer, urinary catheter, and medications for nausea, moderate to severe pain, seizures, and additional cardiac indications. Controlled substances are not commonly available in medical kits on US airlines but may be available in kits on some non-US airlines.
Commercial aircraft carry oxygen bottles intended for short-term use by flight crew during sudden depressurization. Airline oxygen bottles deliver oxygen to passengers at low (2 L/min) or high (4 L/min) settings, which may be sufficient to address the need for oxygen at cruising altitudes.27,50 These oxygen stores generally do not fully meet the needs of persons with respiratory failure. The number of oxygen bottles on an individual aircraft varies, and there is no requirement to carry enough portable oxygen to administer to a passenger for the duration of a flight.
Several organizations recommend contents for an optimal medical kit.51-58 Some have suggested that common emergency medical kits lack adequate equipment for pediatric emergencies.59,60 Recommended improvements include standardization of content and location of equipment,61 availability of pulse oximetry,60 and additional medications, including a “major analgesic,”56 naloxone,60 and antibiotics.62 Despite these suggestions, current basic emergency medical kits contain sufficient equipment to handle most IMEs; only a minority of cases require a medication or performance of advanced procedures.1
Ground-based medical support comes from trained medical personnel who provide recommendations for IMEs and preflight screenings.63 Most airlines contract with third-party entities to provide this service.1,13,15,64,65 When an IME occurs on an aircraft, a flight attendant notifies the pilot in command; next, that pilot establishes radio or satellite telephone communications with the ground-based medical support center and the airline operations center. The flight attendant relays information to and from ground-based support via the pilot or through headsets in the cabin. Communication clarity is often a challenge, including device issues and relaying of information, making well-articulated exchanges essential. The effect of ground-based medical support on patient outcomes following an IME has not been studied.
Guided by individual airline policies, airline personnel often seek aid from trained medical professionals, augmenting existing capabilities. Medical volunteers are not generally required to carry proof of their medical license, although this varies by individual airline policy. Volunteers who have a business card or licensure documents ready to share may allay concerns by flight teams about ability to aid. More importantly, medical volunteers must honestly consider their own capability of providing medical care, and if they choose to do so, they should not be under the influence of alcohol or other drugs.66 In one study, approximately half of IME aid was by a physician, 25% by a nurse or other emergency personnel, and 25% by flight crew alone.1 If multiple potential volunteers exist, a collegial conversation about capabilities is optimal; for instance, a specialist physician may be less capable to assess and manage a patient with an IME than another medical volunteer with training and experience more directly linked to the symptoms or condition.
In most cases, the primary role of a medical volunteer is to gather information, assess an ill or injured passenger, aid with communications with any ground-based support, and potentially administer medications or perform procedures. Flight crew particularly seek the recommendations of ground-based medical experts before use of medications or equipment from the emergency medical kit, considering the variability in training and experience of onboard volunteers.67 Medical volunteers may be asked to provide a recommendation, but a consulting ground-based physician usually makes a final recommendation about care. The key to success is for everyone involved to contribute their expertise as part of a collaborative team, with the sole goal of ensuring the best interest of the patient with the IME in consideration of all passengers on board.
In the United States, the Aviation Medical Assistance Act (also referred to as a “Good Samaritan” shield) protects passengers who provide medical assistance from liability except in cases of gross negligence or willful misconduct.68 Medical volunteers who seek compensation in return for providing aid (such as money, seat upgrades, mileage points, or other items of value) may jeopardize their standing under existing immunity laws, although no case law related to this exists.69
Flights outside of the United States are governed by a complex combination of public and private international laws, including the Warsaw Convention, Montreal Convention, and Tokyo Convention.69 In addition to differences in “Good Samaritan” volunteer protections, which are not present in many other countries, the duty to respond also varies by country. For example, in the United States, Canada, England, and Singapore, there is no legal duty for an off-duty medical professional to assist during an IME.69-71 Conversely, Australia and many European countries require physicians to render assistance during IMEs as defined by case law and civil law codes.69,72,73 Regardless of applicable laws, physicians often feel an ethical duty to act.74 According to one study, only 1 case has occurred in the United States involving a physician being sued for assisting in an IME, and that case was dismissed without hearing.69 Considering existing legal protections and international requirements, medical assistance rendered by a capable physician is of little personal legal risk and is supported by experts in aviation medicine.1,56,63,66
Diversion, which involves changing a landing destination because of an IME, is appropriate for several types of medical emergency. A commercial aircraft is not a medical facility, has limited onboard medical equipment, and has no dedicated medical personnel on board who can adequately address all events. However, the decision to divert involves consideration of multiple factors, many unknown to an onboard medical volunteer. Aircraft commonly take off with more fuel than is safe for landing; immediate diversion soon after departure may require dumping a large amount of fuel into the atmosphere (a feature not available in many newer aircraft). The closest possible diversion airport may not have appropriate medical capabilities to manage a patient, negating a time-to-treatment benefit of going to the closest airport. Even if a facility seems nearby, it may take 30 minutes to reach the ground from cruising altitude; flying onward may not result in any meaningful delay in medical treatment. Some patients may not desire to be diverted, especially when they are returning to their home cities, where they can be transported to a familiar health system. Even with a request for emergency medical services to be available at the time of arrival of a patient with an IME, only a third of passengers are transported by emergency medical services to a hospital, and only a third of those transported are admitted to the hospital, either because their condition was not serious or because they ultimately refused care.1
The pilot in command, in coordination with the flight dispatcher, coordinates all operational decisions for the aircraft and is responsible for decisions about aircraft diversion. Any other persons involved in an IME, including flight staff, volunteers, or ground-support experts, are offering recommendations rather than making decisions about diversion. To make these decisions, the pilot in command seeks input from involved medical volunteers while relying largely on the opinion of ground-support physicians. Input from their operations center often affects these decisions, which must account for airport capabilities, fuel on board the aircraft, and other variables.
The direct cost of diversion ranges from $20 000 to $725 0006,60 and varies based on logistical considerations in addition to direct and time costs to reroute other passengers. Although the benefit of diversion is sometimes clear, such as for a passenger who has been resuscitated after cardiac arrest or who has new-onset stroke symptoms, most cases of diversion require balancing multiple factors including the passenger’s condition. In one study, the medical conditions that most frequently resulted in diversion included cardiac arrest, obstetric emergencies, cardiac symptoms, and suspected stroke.1 Despite these symptoms, most patients with an IME are managed with onboard interventions and the situation does not result in diversion, transport to a hospital, or admission. The best decision path for most circumstances is a collaboration among airline personnel, ground-based expert physicians, and any onboard volunteer physicians or other health care professionals. In this manner, it is much like making complex medical decisions in other health care environments with the assistance of a specialty consultant.
Diversion decisions involving a patient in cardiac arrest are complex. If the event occurs at cruising altitude, it can take longer than 30 minutes to land regardless of physical distance to an airport. The pilot and ground-based expert consider these factors and the pilot decides about diversion. Diversion decisions may also depend on operational considerations and the distress of other passengers; in some settings, especially when resuscitation fails, diversion away from the intended destination may not be in the best interest of family members or other passengers.
On request of a flight crew for assistance, medical professionals should identify themselves and report their training and current clinical practice. Next, the assessment should determine the type and duration of symptoms, presence of high-risk symptoms (eg, chest pain, shortness of breath, or focal weakness), vital signs (pulse, blood pressure, and respirations), mental status, and pertinent physical findings. The flight attendant should obtain the emergency medical kit, and oxygen should be administered to the person with the IME if needed. After gathering patient information, the flight attendant should establish contact with any ground-based medical support personnel available and relay this information, including any recommendations for therapeutic interventions or diversion concerns. Any IME triggering a request for a medical volunteer on board is serious enough to warrant contact with ground-based medical personnel; airlines arrange this service for this explicit purpose. Airlines commonly have standardized forms to document care; health care professionals involved in IMEs should request and use these forms. Additional individual recommendations are shown in Figure 1 and Figure 2 (see also the Supplement) along with key diagnoses to consider when assessing passengers with these symptoms (Table 4).
Syncope or near-syncope is the most common category triggering an IME. With both benign and serious etiologies of syncope, most patients initially appear ill, have altered sensorium, and may be pale or sweaty. A common pattern is resolution after limited interventions (supine positioning, elevation of legs, and other basic care), with the passenger often improving to a normal state over 15 to 30 minutes. Initial mild bradycardia and hypotension are common during syncopal events; medical volunteers who do not commonly provide care for patients during a syncopal event may be unfamiliar with finding hypotension at the time of even benign vasovagal syncope. The key is identifying markers of etiology and need for additional interventions, such as administration of glucose or other medications.
Initial assessment of a passenger with chest pain seeks to inform the likelihood of an acute ischemic, pulmonary, vascular, or other serious medical condition. Generally, chest pain that subsides with basic onboard interventions (eg, oxygen or initial medication) is not usually caused by an acute ST elevation myocardial infarction, aortic dissection, or pulmonary embolism that would need diversion. In the event of persistent pain, abnormal vital signs, or ongoing respiratory distress, diversion is an option.
For a passenger with a possible seizure, a history of seizures or use of antiepileptic medications helps define probability of occurrence and potential recurrence. Rapid return (seconds) to a normal mental status suggests a nongeneralized seizure or vasomotor syncope rather than convulsive seizures. A few myoclonic jerks alone are not specific for seizure, as many individuals have these with syncope of any cause. If a well-described seizure stops, the passenger may remain less responsive for 15 to 30 minutes; ongoing observation is the plan for this common scenario. Single-event seizures in which the passenger recovers usually do not necessitate a diversion; multiple or ongoing seizures or failure to recover from a postictal state should prompt consideration of diversion options.
Most trauma on commercial airlines is minor and appropriately addressed with content in the emergency medical kit. Head injuries from falls or tumbling luggage are best assessed for loss of consciousness, persistent head or neck pain, scalp wounds, and any neurological symptoms. Passengers without these factors and with only minor discomfort may be rechecked later in flight or at the destination.
A variety of psychiatric symptoms may manifest on board an airplane, from simple anxiety to acute psychosis.75,76 Anxiety may also produce physical symptoms (eg, chest pain, shortness of breath). Patients may cause disruption and be threatening to other passengers, a challenge in the enclosed environment of an aircraft.77-79 Most cases of acute agitation or anxiety can be managed through verbal calming techniques. Consider administration of a patient’s own medication if taken for anxiety and carried on board. The FAA-mandated emergency medical kit has little content that could be used for agitation.
Allergic reactions often occur in flight but are rarely serious, accounting for 1.6% of IMEs (Table 1).80 Food-related allergies are the most common inciting cause of symptoms, especially peanuts or tree nuts,80-83 and other allergens may include exposure to traveling pets84 and other environmental allergens. Specific treatment for allergic reaction includes diphenhydramine. Anaphylaxis may be treated with epinephrine and oxygen. If available from an enhanced medical kit, corticosteroids may be administered.
Obstetric emergencies are a small proportion of IMEs (0.7%) (Table 1) but can be distressing for both the mother and the medical volunteer, who is unlikely to have experience managing obstetric emergencies. Most health care professionals recommend no flying in commercial aircraft beyond 36 weeks’ gestation for single pregnancies or beyond 32 weeks for multiple gestations.56 Vaginal bleeding or abdominal pain before 20 weeks’ gestation does not typically require diversion or specific interventions during the flight beyond coordination of emergency medical services personnel on arrival. Pregnancy complications after 20 weeks’ gestation or initiation of labor should prompt an urgent call to ground-based medical support to consider diversion.
For a patient with suspected cardiac arrest, resuscitate using standard cardiopulmonary resuscitation approaches.85 Provide chest compressions at a rate of 100/min to 120/min in adults with 1 breath every 5 to 6 seconds or use compression-only cardiopulmonary resuscitation. Apply an automated external defibrillator as soon as possible. If capable, place an intravenous line and administer epinephrine, 1 mg (0.1 mg/mL) every 5 minutes. Lidocaine, 100 mg intravenously, is an option for persistent ventricular fibrillation or ventricular tachycardia in adults. Termination of resuscitation may be appropriate after 20 to 30 minutes of resuscitation without return of circulation.86
Quiz Ref IDThe most effective way to address IMEs is to prevent them. The risk of syncope increases with dehydration in the setting of a low-humidity environment, pressure changes, and exhaustion. Travelers should hydrate often and eat scheduled meals and snacks during travel, especially with connecting or extended flights. Physicians and nurses assisting flight travel plans for patients with chronic medical conditions should consider and educate patients on the effects of altitude, need for routine medications, and potential occurrence of medical emergencies. For example, glucometers are not part of the FAA-mandated emergency medical kit contents; a patient with diabetes should carry a glucometer, glucose supplements, and diabetes medications on board. Passengers at risk of symptomatic hypoxia need to have a portable oxygen concentrator for the flight. Multiple studies suggest that the hypoxic challenge test (exposure to 15% oxygen in nitrogen) correlates better with in-flight hypoxia than preflight oximetry, forced expiratory volume in 1 second, or the commonly used 50-m test (ability to walk 50 m).87-89 However, the hypoxic challenge test is not routine or commonly available. A reasonable estimate of need for in-flight oxygen can use published equations and a passenger’s ground-level Pao2 and Paco2 measurements.90,91 Passengers with portable oxygen concentrators should have battery life that exceeds the duration of the flight (preferably 150% of flight time) to account for unforeseen delays. Parents traveling with children should bring medications in pediatric formulations because these are not commonly available in emergency medical kits.
For patients with acute or other specific medical conditions, the International Air Transport Association recommends appropriate time intervals for fitness to travel, which are available online.56 For other conditions, health care professionals should consult with flight and medical transport experts.
In-flight medical emergencies most commonly involve near-syncope and gastrointestinal, respiratory, and cardiovascular symptoms. Health care professionals can aid during these emergencies as part of a collaborative team involving the flight crew and ground-based physicians.
Corresponding Author: Christian Martin-Gill, MD, MPH, Department of Emergency Medicine, University of Pittsburgh, 3600 Forbes Ave, Iroquois Building, Ste 400A, Pittsburgh, PA 15261 (email@example.com).
Accepted for Publication: November 20, 2018.
Author Contributions: Dr Martin-Gill had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: All authors.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: All authors.
Critical revision of the manuscript for important intellectual content: All authors.
Administrative, technical, or material support: All authors.
Supervision: Martin-Gill, Yealy.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Drs Martin-Gill, Doyle, and Yealy reported that they oversee the University of Pittsburgh Medical Center Medical Communications Center, which provides ground-based medical support for commercial airlines. Dr Yealy reported receipt of grants from the National Heart, Lung, and Blood Institute and royalties from McGraw-Hill, Lippincott Williams & Wilkins, and Oxford Press.