Effect of Altitude in Oxygenation

Abstract

The air medical transport of cardiac patients is a rapidly expanding practice. For various medical, social, and economic indications, patients are being flown longer distances at commercial altitudes, including international and intercontinental flights. There are data supporting the use of short-distance helicopter flights early in the course of a cardiac event for patients needing emergent transfer for percutaneous coronary intervention or aortocoronary bypass. When considering elective long-distance air medical transport of cardiac patients for social or economic reasons, it is necessary to weigh the benefits against the potential risks of flight. A few recent studies suggest that long-distance air medical transport is safe under certain circumstances. Current guidelines for air travel after myocardial infarction do not address the use of medical escorts or air ambulances equipped with intensive care facilities. Further research using larger prospective studies is needed to better define criteria for safe long-distance air medical transport of cardiac patients.

Introduction

The use of air medical transport services provided by private and insurance company-affiliated air ambulance companies has risen significantly over the past 15 years. In 1992 alone, the 250 US-based and 12 internationally based air medical transport operators belonging to the Association of Air Medical Services performed > 160,000 transfers over a wide range of distances.1 For a combination of medical, social, and economic reasons, cardiac patients with increasing acuity of illness are being transported distances spanning the globe. (De, 1997).

Air medical transport is performed using rotary wing aircraft (i.e., helicopter) or fixed-wing aircraft (e.g., engine propeller or jet air ambulance, or medical escort on a commercial airline). Rotary-wing aircraft are used for emergency transport over short distances, whereas fixed-wing aircraft are used for transport over longer distances (e.g., > 150 miles).2 For long-distance transport that is elective (i.e., for economic and/or social reasons), patients in relatively stable condition may be medically escorted aboard a commercial aircraft. Elective long-distance transport of patients in less stable condition (e.g., early post-myocardial infarction [MI], receiving mechanical ventilation, or receiving IV vasopressors or antiarrhythmic agents) and emergency long-distance transport is performed using fixed-wing air ambulances. The type of fixed-wing aircraft used for air ambulance transport generally depends on the distance to be travelled, with single- or twin-engine propeller aircraft reserved for shorter flights, whereas jets may even be used to transport across continents. The quality of air ambulance services may vary across companies. Generally, air ambulances should be configured to function as flying ICUs with a full range of pharmaceuticals, and compact portable medical equipment including IV pumps, cardiac and homodynamic monitor, defibrillator, ventilator, pulse oximetry, and blood gas analyzer. The medical crew should include an intensive care trained physician, nurse, and/or medic(Proctor, 1993).

When air medical transport is considered elective (e.g., repatriation of patients from foreign countries where quality medical care is available), the risks and benefits should be considered. The social benefit of returning patients to their country is treatment in their language near their family and support system. For patients with travel insurance, if the anticipated cost of hospitalization ...