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The Challenge of In-Flight Emergencies
Five hours into a transatlantic flight from Philadelphia to Paris, a flight attendant finds a 47-year-old woman unresponsive in a cabin restroom. The patient's husband started knocking on the restroom door after his wife was inside for approximately 15 minutes. When there was no response, he called a flight attendant to unlock the door. The flight attendant dragged the patient out of the restroom and requested medical assistance via the overhead pager. A firefighter, a physician and I immediately responded to the request.
Upon arrival, we found the patient supine and unresponsive, with feces and urine covering her pants. She was not breathing and had no carotid pulse. We immediately started chest compressions. According to the patient's husband, the woman had a medical history of diabetes and cardiomyopathy leading to the placement of an implantable cardioverter-defibrillator. We requested the automated external defibrillator (AED), oxygen and medical bag from the flight attendant. While continuing chest compressions, we gave the patient 100% oxygen via bag-valve mask. A laryngoscope and endotracheal tube were not available in the first aid kit. We attached the AED pads to her chest and waited for rhythm analysis. No shock was advised. We proceeded to the Advanced Cardiac Life Support (ACLS) survey without knowledge of the patient's heart rhythm. I obtained a finger stick, which resulted in a blood glucose of 238 mg/dl. We attempted venous access on both arms unsuccessfully. Twenty minutes into the resuscitation attempt, a cardiologist, who was sitting in first class and had not heard the initial request for help, arrived on scene. He administered 1 mg of intracardiac epinephrine. We continued chest compressions for another 10 minutes, for a total resuscitation time of roughly 30 minutes. Shocks were never advised by the AED throughout the resuscitation attempt. The patient never regained a pulse.
Discussion
Approximately 2 billion passengers travel aboard commercial airlines each year.1 The estimated incidence of in-flight medical events worldwide is 1 in 14,000 passengers.2 Furthermore, a study conducted by the Federal Aviation Administration (FAA) found a rate of 13 medical events a day among domestic flights between 1996 and 1997.2 A recent retrospective review revealed a total of 10,189 in-flight medical emergencies between 2002 and 2007 aboard 32 European airlines.3 The leading causes of medical events in this study were syncope (5,307 cases, 53.5%), gastrointestinal disorders (926 cases, 8.9%) and cardiac conditions (509 cases, 4.9%).3 In the six-year study period, 52 deaths (0.5% of cases) occurred in flight.3
Since 1986, all commercial flights carrying more than 30 passengers have been required to carry basic emergency kits.2 In 1997, U.S. airlines began to introduce AEDs on aircrafts and in airport terminals. Over two years (from June 1, 1997 through July 15, 1999), AEDs were used 191 times on aircraft, with 29 deaths (15.2%).4 The FAA currently requires emergency kits to include airway devices, IV kits and certain ACLS medications, among other equipment (Table 1).
High altitude coupled with decreased barometric pressure during flight is associated with several physiologic changes. Federal Aviation Regulations require American aircrafts to maintain the cabin altitude pressure at no more than 8,000 ft (2,438 m) while in flight5--that is to say, no matter the altitude of the aircraft, the cabin pressure can't be any lower than that found at 8,000 feet. At this altitude, alveolar oxygen tension decreases to 65 mmHg, leading to a fall in arterial oxygen tension (PaO2) to 60 mmHg.6 Although in healthy individuals this may result in a slight decrease in oxyhemoglobin saturation, compensation occurs by increases in minute ventilation and cardiac output.1,[7] In individuals with pre-existing cardiac or pulmonary conditions, such as heart failure or chronic obstructive pulmonary disease, compensation is a greater challenge, given that the individual is already on a steeper portion of the oxygen-hemoglobin dissociation curve. Additionally, hypoxemia and the resulting reflex tachycardia may exacerbate ischemic heart disease.1 Lastly, there is an increased risk, peaking with flights greater than 8 hours, for venous thromboembolic events.7
Conclusion
Given that the AED never interpreted a shockable rhythm, our patient likely experienced a pulseless electrical activity (PEA) or asystolic cardiac arrest. Although there are a myriad of causes for both conditions, myocardial infarction and pulmonary embolism are at the top of the differential. She had several risk factors for pulmonary embolism, including heart failure, obesity, age greater than 40, and immobilization.8 Similarly her risk factors for myocardial infarction included diabetes mellitus, obesity, pre-existing cardiac disease and in-flight hypoxia. Managing either event in flight is challenging, given the lack of medical resources. Nonetheless, good BLS with ACLS medication administration is a feasible option on a commercial aircraft.
As of 2004, all commercial American aircraft requiring flight attendants and having a maximum payload capacity of greater than 7,500 lbs. are required to have AEDs on board.9 Flight attendants must be trained in BLS and AED use.10 Additionally, most airlines have land-based medical command physicians who help manage medical emergencies with flight attendants or health professionals on board. Although staffing every commercial aircraft with a healthcare provider may not be financially reasonable, a cost-effectiveness analysis should be conducted. All providers who fly on commercial flights should be familiar with resources available prior to traveling (see Table 1). Lastly, people with cardiac or pulmonary comorbidities should consult a physician prior to flying.
References
1. Kahn RA, Ruckman RF, Brown SB. Cardiac arrest at 30,000 feet. J Cardiothorac Vasc Anesth 120: 438–444, 2006.
2. Gendreau MA, DeJohn C. Responding to medical events during commercial airline flights. N Engl J Med 346: 1067–1073, 2002.
3. Sand M, Bechara FG, Sand D, Mann B. Surgical and medical emergencies on board European aircraft: A retrospective study of 10,189 cases. Crit Care 13(1): 121, 2009.
4. Page RL, Joglar JA, Kowal RC, et al. Use of automated external defibrillators by a U.S. airline. N Engl J Med 343: 1210–16, 2000.
5. Cabin cruising altitudes for regular transport aircraft. Aviat Space Environ Med 29: 433–39, 2008.
6. Cottrel JJ. Altitude exposures during aircraft flight: Flying higher. Chest 93: 81–84, 1988.
7. Silverman D, Genreau M. Medical issues associated with commercial flights. Lancet 373: 2067–2077, 2009.
8. Lapostolle F, Surget V, Borron SW, et al. Severe pulmonary embolism associated with air travel. N Engl J Med 345: 779–783, 2001.
9. Delaune EF 3rd, Lucas RH, Illig P. In-flight medical events and aircraft diversions: One airline's experience. Aviat Space Environ Med 74(1): 62–8, Jan 2003.
10. Drummond R, Drummond AJ. On a wing and a prayer: Medical emergencies on board commercial aircraft. CJEM 4(4): 276–80, Jul 2002.
11. U.S. House of Representatives Subcommittee on Aviation. Medical kits on commercial airlines, https://commdocs.house.gov/committees/Trans/hpw105-23.000/hpw105-23_0f.htm.
Jonathan Ludmir, BA, EMT-B, is a member of the Volunteer Medical Service Corps of Lower Merion and Narberth, Ardmore, PA, and a 2011 graduate of the University of Pennsylvania School of Medicine.
