Case study #1 (see attached) tells about a patient, Maria, who has a history of hypertension and high cholesterol and 30 pack a year smoking.i Although normally under control with medication, upon traveling by plane she experienced what she thought was new condition with new symptoms which would ultimately be diagnosed as chronic heart failure.
Maria's recent history showed that she was experiencing difficulty breathing on exertion, fatigue, abdominal bloating, lower edema, diaphoresis and dizziness among other symptoms. All of these symptoms and medical history point to chronic heart failure (CHF). Maria experienced an intensification of these symptoms while flying from Florida to Denver. If Maria would not have ignored the signs that were presenting themselves, she may not have flown. The cabin air system in today's jetliners is designed to provide a safe, comfortable cabin environment at cruising altitudes that can reach upwards of 40,000 feet. At those altitudes, the cabin must be pressurized to enable passengers and crew to breathe normally. By government regulation, the cabin pressure cannot be less than the equivalent of outside air pressure at 8,000 feet.ii
In CHF, a person is already having difficulty supplying oxygen sufficiently to the body. When you increase in altitude, oxygen levels decrease. Although a normally functioning heart and lungs can adjust to the decreased pressure, a person with impaired heart and lung functions may present with intensified symptoms which may become a medical emergency. In a study by the National Institute of health, in which 464 CHF patients (response rate = 39%) returned completed survey questionnaires, 35% (89/252) of patients who flew experienced health-related problems (these are patients who knew of their condition). 9% (8/89) of patients experienced breathlessness, dizziness, swollen ankles, headache, and chest pain. 3 of 8 patients used in-flight oxygen due to