Air Travel Emergencies
Physicians commonly help with in-flight medical events (IME). Many IME fall outside a practitioner’s normal scope of practice. The aircraft environment is cramped with limited medical resources. Despite these obstacles, health care workers should be prepared to render assistance in these situations.
- 4 billion passengers travel annually worldwide (1).
- Exact incidence of IMEs is unknown.
- Airlines estimate an IME occurs on 1 in 40 flights, most are minor and handled by the flight crew.
- Other databases, which include only more serious IMEs, estimate incidence at 1 in 600 flights (2).
- Airline estimates are that there is an IME in 1 per 7,500 to 40,000 airline passengers 250 to 1,500 events/day worldwide (3).
- The likelihood of encountering an IME is increasing because of larger aircrafts, longer flights, and an aging population.
- The most common IMEs involve syncope/near syncope (32.7%), gastrointestinal (14.8%), respiratory (10.1%), and cardiovascular symptoms (7%) (3).
- In otherwise healthy passengers, vasovagal syncope represents up to 90% of IMEs.
- 5% of passengers suffer from a chronic illness and account for two-thirds of IMEs.
- 15% of ground-based physician calls are for pediatric passengers (1).
- 3% of IMEs are fatal; however, death may be underreported as it is often not declared in-flight.
Etiology and Pathophysiology
Hypobaric hypoxia: Atmospheric pressure of oxygen drops from 160 mm Hg at sea level to 120 mm Hg at cruising altitude in a pressurized cabin.
- In healthy people, the arterial oxygen tension drops from 100 to about 60 mm Hg with associated mean inflight oxygen saturations of 93% (range: 85 to 98) (4).ALERT
Passengers with chronic obstructive pulmonary disease (COPD) or other pulmonary disorders have a lower baseline PaO2, so the drop in oxygen tension may occur on the steep part of the hemoglobin dissociation curve and result in more significant hypoxemia.Alert
Passengers with unstable angina or heart failure may not be able to compensate for hypoxia.
- Gas expansion: Gases expand about 30% in flight. This can lead to a pneumothorax, wound dehiscence or perforation from bowel gas expansion, sinus pressure, and tympanic membrane rupture in children with ear infections.
- Venous thromboembolism: There is an increased risk for clotting because of prolonged sitting, hypoxic conditions, and dehydration. There is an increased risk of deep vein thromboses (DVTs) on longer flights and in passengers with underlying medical conditions.
- Stress: Travelling is mentally and physically stressful, which may lead to psychiatric emergencies or acute coronary syndrome (ACS).
- Insomnia: Passengers have disrupted circadian rhythms, which may trigger seizures and contribute to medication nonadherence.
- Turbulence: Motion sickness is common and traumatic injury can result from falling luggage.
- Medication nonadherence: Forgotten or checked medications may lead to glycemic control problems, seizures, blood pressure instability, and inaccessible as needed medications.
- Decreased access to food and drink: Vasovagal syncope may result from dehydration. Diabetics may suffer hypoglycemia.
- Low air humidity: Cabin air is less than 20% relative humidity which contributes to dehydration, epistaxis, and asthma or COPD exacerbations.
- Viral infections: Parainfluenza and influenza are the most common viruses communicated by proximity. The cabin air is filtered and not infectious.
Transmission of SARS-CoV2 virus can occur on air travel. Like other viruses, the risk is mostly from proximity to infected, possibly asymptomatic passengers rather than cabin air flow. Risk may be mitigated by following applicable guidelines for mask-wearing, social distancing, and quarantining.
- Recent surgery: Passengers are at risk for wound dehiscence, bowel perforation, and compartment syndrome from gas expansion.
- COPD, asthma, CHF, or coronary artery disease: Passengers may suffer from hypoxemia and not be able to compensate appropriately.
- Recent cast placement: Passengers are at risk for compartment syndrome due to tissue edema.
- Hypercoagulability: Passengers with inherited or acquired hypercoagulable conditions, pregnancy, medications, heart disease, or recent surgery are at increased risk for DVTs.
- Recent scuba diving: Passengers are at risk for decompression syndromes.
- Long flights: The effects of hypoxia are cumulative and time-dependent.
- Travelers should discuss medications with their doctor and bring necessary medications and equipment onboard.
- Supplemental inflight oxygen is required for patients with a baseline PaO2 < 70 mm Hg or who are unable to walk a flight of stairs or 150 feet without becoming short of breath or experiencing angina.
Women are generally safe to fly until 36 weeks’ gestation.
Travelers with children should bring liquid formulations of medication in allowed quantities on the plane. Children with asthma should have a rescue inhaler with spacer and facemask.
- Specific guidelines:
- Avoid flying 10 to 14 days after surgery (varies by type of surgery).
- Casts may need to be bivalved if applied 24 to 48 hours before a flight.
- Avoid scuba diving 24 hours before flying.
- DVT prevention (5)[C]:
- Adequately hydrate.
- Avoid venous stasis by standing, stretching, and exercising legs in flight.
- Passengers with risk factors may need compression stockings, aspirin, or anticoagulation.
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