The controlled emergency swimming ascent (CESA) is a standardized exercise in diving training. Despite strict safety precautions, this technique carries risks, particularly for the occurrence of pulmonary barotrauma, as the case report of a diving accident illustrates.

Case report
A 23-year-old healthy male diver suffered pulmonary barotrauma with cerebral arterial gas embolism (CAGE) after performing a controlled emergency swimming ascent (CESA) during a beginner's course. The exercise required descent to 6 meters, removal of the regulator from the mouth and continuous exhalation during ascent, followed by manual inflation of the BCD at the surface. Immediately after inflating the BCD, the diver briefly went blind and lost consciousness. While being pulled to shore by the instructor, he could hear his voice but was unable to speak and felt a pronounced weakness in the right side of his body. He also complained of stabbing pains in the left side of his chest.
When the emergency services arrived, around 20 minutes after the incident, the vital signs were normal and the weakness on the right side had completely subsided. After a further 30 minutes in the emergency room, all neurological symptoms had subsided, only the left-sided chest pain persisted. An X-ray of the chest showed a small pneumothorax at the tip of the left lung. Further computed tomography confirmed bilateral pneumothoraces of the lung tips, a pneumomediastinum (accumulation of air in the space around the heart, bronchi, trachea and esophagus) and a pneumopericardium (air in the pericardium).
Despite the initial diagnosis of pulmonary barotrauma with concomitant cerebral arterial gas embolism, no neurological deficits were noted. Due to the rapid spontaneous recovery and bilateral pneumothoraces, which would have required chest drainage, hyperbaric chamber treatment was not performed. Instead, the patient received normobaric oxygen therapy overnight. On the following day, he was largely clinically recovered, apart from slight balance problems. He was discharged with a temporary ban on diving. Follow-up examinations one and two months later revealed no abnormalities, and both the CT scan and the pulmonary function test were normal. The patient was advised to refrain from diving for at least six months and to critically reconsider whether he wished to continue diving.
CESA
The controlled emergency swimming ascent (CESA) procedure was originally introduced as an emergency strategy for out-of-air situations and is still part of many diving training programs today. While the risk of pulmonary barotrauma or arterial gas embolism during CESA is considered low - a PADI study found an incidence of 0.31 cases per 100,000 ascents - some diving organizations have questioned the benefits of this training. For example, the Belgian underwater association has removed CESA-exercises from its training program after a significant number of barotrauma cases were documented during such training. Other organizations, including PADI, continue to insist on an emergency ascent from 6 to 9 meters under the strict supervision of the instructor.
CESA is obsolete.
However, the case described here illustrates the potential risks of the procedure, even if it is carried out in accordance with the rules. The diver suffered a pulmonary barotrauma with an arterial gas embolism despite correct use of CESA, which raises questions about the necessity of this training. Alternative safety measures now exist, such as adhering to minimum gas rules, practicing alternate breathing or using the buddy's backup regulator, which are taught as standards in modern beginner courses. This makes the specific training of a CESA obsolete - in recreational diving, not to mention technical diving.
Pneumothorax and return to diving
A general diving ban was not issued in this case, as the pneumothorax did not occur spontaneously, but as a result of an emergency situation that should generally be avoidable through appropriate training. Nevertheless, the question remains as to whether a hidden predisposition could have contributed to the development of the pulmonary barotrauma.
Air trapping as a possible risk factor
It is mentioned in passing that the patient had asthma as a child. However, it remains unclear whether a bronchoprovocation test (targeted triggering of bronchoconstriction by inhalation of irritating substances) was carried out as part of the pulmonary function tests in order to rule out a residual asthma problem. Undetected or inadequately controlled asthma can significantly increase the risk of pulmonary barotrauma due to air trapping (air trapping in the alveoli due to impaired exhalation as a result of bronchial inflammation or constriction).
As asthmatics are only considered fit to dive if their asthma is well controlled (with medication), a detailed assessment is strongly recommended in this case. Undiagnosed asthma could significantly increase the risk of future diving incidents and should therefore be carefully investigated before a decision is made to resume diving.
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