- An air embolism is the most serious dysbaric injury and requires aggressive care, which includes 100% oxygen, intravenous fluids, and hyperbaric treatment. Patients are placed in the Trendelenburg or left lateral decubitus position to minimize the passage of air emboli to the brain.
- Since nitrogen is not metabolized, it remains dissolved until the nitrogen gas pressure in the lungs decreases and the nitrogen can be removed. During a slow ascent, as the surrounding pressure decreases, the nitrogen that is absorbed into the tissues is released into the blood and the alveoli, but if the ascent is too quick, nitrogen levels do not have the opportunity to equalize among the tissues, blood, and alveoli, which results in the gas coming out of solution and forming gas bubbles in the blood or tissue.
- The treatment of choice for most air emboli and decompression illnesses is hyperbaric (recompression) therapy. This is initiated as soon as possible, ideally within 6 hours of the onset of symptoms.
Dysbaric injuries may be the result of several distinct events that expose an individual to a change in barometric pressure. The first possible etiology is an altitude-related event, which can be illustrated by the rapid ascent or descent during airplane transport or sudden cabin decompression at an altitude of 25 000 ft. The second type of dysbaric injury results from an underwater diving accident. A third dysbarism is caused by a blast injury that produces an overpressure effect. This section primarily discusses dysbaric diving injuries and, to a lesser extent, aviation-related dysbarisms. Blast injuries are beyond the scope of this chapter.
Scuba (self-contained underwater breathing apparatus) diving (Fig. 142–1) was developed in the mid-1940s and currently allows the sport diver to descend to depths >100 ft. There are an estimated 9 million certified scuba divers in the United States. Worldwide, the diving population continues to grow at a rate of 20% per year. There are a number of recreational diving organizations that have minimum age requirements for certifications. In general, candidates must be 15 or 16 years old for full certification. Pool-based divers may be certified at the age of 8 years, and some organizations will certify 10-year olds for ocean diving to 40 ft (12 m). However, certification is not required to dive. It is the untrained or poorly trained individual who is at greater risk for injury.
There are an estimated 9 million certified scuba divers in the United States. (Photo courtesy of Ron Lachman.)
Scuba diving requires absolute adherence to safety rules and a modicum of common sense. Serious diving-related injuries and fatalities are rare and are often associated with unsafe behaviors or hazardous conditions. However, they can occur without apparent cause. On the average, each year, the Divers Alert Network receives more than 900 scuba diving injury notifications.1 From 1995 to 2006, ...