Diving and Hyperbaric Medicine Volume 43 No. 4 December 2013 232 The diving doctor’s diary Pneumomediastinum or lung damage in breath-hold divers from different mechanisms: a report of three cases Akin Savaş Toklu, Mustafa Erelel and Abdullah Arslan Abstract (Toklu AS, Erelel M, Arslan A. Pneumomediastinum or lung damage in breath-hold divers from different mechanisms: a report of three cases. Diving and Hyperbaric Medicine. 2013 December;43(4):232-235.) Normally pulmonary over-inflation is not an issue during breath-hold diving, in contrast to lung squeeze. Compared with compressed air diving, pulmonary barotrauma is rare in breath-hold diving. Several mechanisms can lead to an increase in intrathoracic pressure in breath-hold diving that may cause alveolar rupture. Here we report three cases of pulmonary barotrauma in breath-hold diving. Using high-resolution chest tomography, bullous damage in Case 1, and pneumomediastinum in Cases 2 and 3 were detected. Transient neurological symptoms in Cases 1 and 2 suggested cerebral arterial gas embolism. The mechanisms that caused intrapulmonary overpressure were, respectively, lung packing (‘buccal pumping’), considerable effort and straining at depth, and breathing compressed air at depth and ascending without exhaling. All three cases recovered without specific treatment such as recompression. Key words Breath-hold diving, freediving, pulmonary barotrauma, arterial gas embolism, cerebral arterial gas embolism (CAGE), buccal pumping, case reports Introduction Breath-hold diving is associated with a variety of physiological responses induced by immersion, apnea and lung compression. 1 Normally pulmonary over-inflation is not an issue during breath-hold diving, in contrast to lung squeeze. 2 Compared with compressed air diving, pulmonary barotrauma (PBT) is rare in breath-hold diving. Nevertheless, several mechanisms can lead to an increase in intrathoracic pressure. 2 Alveolar rupture can cause pneumothorax, pneumomediastinum, surgical emphysema and arterial gas embolism (AGE) and may occur when intrapulmonary pressure is higher than environmental pressure, such as in divers and aviators or airline passengers and mechanically ventilated patients. 3,4 PBT may also be caused by repeated bearing down to increase abdominal pressure, sneezing, vomiting and oesophageal rupture. PBT is especially a risk for divers using scuba or surface-supply breathing apparatus (SSBA). Gas may escape from ruptured alveoli to the interstitial space, tracking along perivascular sheaths or entering the pulmonary circulation via torn pulmonary vessels to reach the left heart, leading to AGE. 5 Cerebral (CAGE) or coronary AGE are the most dangerous complications of pulmonary barotrauma and CAGE is a major cause of mortality in diving. 6 We report three cases of breath-hold (BH) divers who suffered PBT from three different but well-documented mechanisms and presented between 2010 and 2012. Patients gave their verbal consent for their cases to be reported. Case reports CASE 1 A 40-year-old, otherwise healthy, male, competitive breath-hold diver, who was in the habit of lung packing (glossopharyngeal insufflation or ‘buccal pumping’) prior to breath-holding, made a dive in a swimming pool to a depth of approximately 1.5–2 metres of water for dynamic apnea training. He performed lung packing for 20 seconds prior to the dive. He felt dizziness, nausea and numbness all over his body 10 seconds after his dive started, and was unable to control the right side of his body and had visual disturbances Editor’s note: Pulmonary barotrauma (PBT) and its consequences are well recognised in scuba diving, but less so in association with breath-hold diving. The same may be said for iatrogenic PBT and arterial gas embolism (AGE), and failure to recognise these may (and sadly often does) lead to tragic consequences. These five cases, and a later letter to the Editor regarding retrograde venous gas embolism have been put together to remind clinicians to always be on the lookout for these complications. I have myself managed breath-hold divers who have taken a breath from a scuba regulator at depth, leading to AGE, and iatrogenic cases similar to the one reported by Janisch et al.