RESUMEN
The authors present a case of an 86-year-old man who developed tension pneumothorax while receiving hyperbaric oxygen therapy (HBOT) for adhesive intestinal obstruction. The patient experienced general malaise and was admitted to our hospital with abdominal pain due to intestinal obstruction, which was revealed by computed tomography on day 3. He received HBOT from day 5. On day 6, while receiving the 2nd session of HBOT, he experienced severe dyspnea and backache after decompression and developed cardiac arrest soon after he was moved out of the compression chamber. Tension pneumothorax was detected, and he was successfully resuscitated by immediate thoracic drainage. Though tension pneumothorax during HBOT is extremely rare, it is a life-threatening emergency. Therefore, it is essential to detect and manage pneumothorax prior to HBOT.