Pulmonary overinflation syndrome (POIS) is a group of barotrauma-related diseases caused by the expansion of gas trapped in the lung, or over-pressurization of the lung with subsequent over-expansion and rupture of the alveolar air sacs. This group of disorders includes arterial gas embolism, tension pneumothorax, mediastinal emphysema, subcutaneous emphysema and rarely pneumopericardium. In the case of diving activities, POIS is rarely reported and is frequently related to unsafe diving techniques. We report a classical case of POIS in an underwater logger while cutting trees for logs in Tasik Kenyir, Terengganu. The patient, a 24-year-old worker, made a rapid free ascent to the surface after his breathing equipment malfunctioned while he was working underwater. He suffered from bilateral tension pneumothoraces, arterial gas embolism giving rise to multiple cerebral and cerebellar infarcts, mediastinal and subcutaneous emphysema as well as pneumopericardium. He was treated in a recompression chamber with hyperbaric oxygen therapy and discharged with residual weakness in his right leg.

Rozali, Sulaiman, Zin, Khairuddin, Abd-Halim, Sherina, , , (2006). Pulmonary overinflation syndrome in an underwater logger. The Medical journal of Malaysia, 2006 Oct;61(4):496-8. https://www.ncbi.nlm.nih.gov/pubmed/17243532