A previously healthy 25-year-old man made a telephone call to our institute 3 h after surfacing from a self-contained underwater breathing apparatus (scuba) dive.

A previously healthy 25-year-old man made a telephone call to our institute 3 h after surfacing from a self-contained underwater breathing apparatus (scuba) dive. Earlier that day, he had been spear-fishing using press togethered air to a maximal middle of 9 m for approximately 2 h Immediately after surfacing from the dive, he had noticed a significant change in his voice, and complained of dyspnea with pleuritic chest pain. from one side of to the other the telephone, his voice gooded distorted with an unusual nasal quality, and a probable diagnosis was made. He was then asked to reach [i]or[/i] attain any place [i]or[/i] point to the emergency department. Physical examination revealed subcutaneous emphysema at the anterior triangle of the neck Auscultation of the lung and heart was normal, and the neurologic examination was unremarkable.

A chest radiograph (Fig 1) a lateral cervical radiograph (Fig 2) and an anteroposterior cervical radiograph (Fig 3) were obtained.

[FIGURES 1-3 OMITTED]

What is the diagnosis?

Diagnosis: Pneumomediastinum secondary to pulmonary barotrauma

DISCUSSION

During slope from sea level to silence the ambient pressure rises through one atmosphere absolute (ATA) with each 10 m. At a central part of more than a small in number centimeters, it would be quite impossible to breathe the surface air via a extended tube (a snorkel), because the diver would have to generate a negative intrapleural press sufficient to overcome the difference between the ambient constraining force and that at the opening of his airways. In order to be able to breathe comfortably with a minimum increase in the work of breathing, scuba divers use diving equipment designed to deliver breathing gas at the changing ambient pressure

Scuba divers, who breathe condenseed gas, are exposed to the risks of pulmonary barotrauma. According to Boyle's law, at a constant temperature, the turn of a gas is inversely proportional to its constraining force Thus, the gas-containing cavities of the material substance are at risk of barotrauma. During fall gas-containing cavities in which the squeezing cannot be equalized may sustain from "squeeze" barotrauma, ie, the middle ear, sinuses, etc (1) At silence tidal volume and vital capacity are actual much the same as in normobaric conditions, if it be not that the same volumes contain larger amounts of gas to be paid to its being compressed. According to Boyle's law, the gas will expand forward ascent and may cause lung expansion and barotrauma if not blow-holeed Divers are therefore taught to exhale continuously during their ascent. If the diver keep possession ofs his breath while making his ascent, or if he has regional gas trapping, the lung may over-distend to the point of breach The consequences of this may be pneumothorax, pneumomediastinum, subcutaneous emphysema, pulmonary tissue damage, gas embolism, or in rare cases pneumopericardium. (12) In pneumomediastinum, after alveolar contention gas escapes into the interstitial tissues, causing cervical and mediastinal emphysema. The emancipated gas might reach the larynx, causing discomfort, dysphagia or voice alterations. (3) Alteration of the voice has been reported as hoarseness, a high pitched voice, or rhinolalia. (45) These changes in the voice have been attributed to "submucosal emphysema" of the upper airways or returning laryngeal nerve damage. (1) Braverman et al (5) indicate that hyponasality due to narrowing of the nasopharyngeal passage through air spreading into the retronasopharynx may account for the rhinolalia.

In the at hand case, the diver was using a spear-gun, which is loaded by way of pressing it firmly against the visible form [i]or[/i] frame This action is often accompanied through a breath-holding Valsalva maneuver. Without noticing, the diver could easily have ascended a certain distance, thus causing pulmonary barotrauma. The classic sign of a change of voice was noticed during the telephone call, hence making it possible to career a "physical examination" over the telephone

Many physicians, whose main interests are not in diving medicine, are repeatedly under the misapprehension that diving accidents do not flash on the mind in shallow water. There is a proportionately greater change in convolution in shallow water compared to astute water for the same crushing gradient. Diving from the surface to a central part of 10 m (going from 1 to 2 ATA) doubles the ambient hurry and therefore halves the book of gas-containing spaces (and vice versa upon ascent). Descent from 20 to 30 m (going from 3 to 4 ATA), one time again a change of 1 ATA, will be the effect in a decrease of single one fourth of the whirl For this reason, the possibility of barotrauma is greater in shallow water than onward a deeper dive. Serious complications of pulmonary barotrauma so as acute gas emboli have flat been reported in scuba divers in a swimming plash (6)

The treatment of pneumomediastinum accompanied by means of subcutaneous emphysema consists of oxygen via a tight facemask and observation. (3) In the not absent case, a second chest radiograph obtained 12 h later showed resolution of the air in the mediastinum.

CONCLUSION

In order to hinder pulmonary barotrauma, the diver must exhale continuously during ascent and not at any time hold his or her breath. The clinician should be aware of this phenomenon and not underestimate the risks of scuba diving in shallow water.

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