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