Pulmonary edema and hemoptysis after breath-hold diving at residual volume

Abstract

To simulate pressure effects and experience thoracic compression while breath-hold diving in a relatively safe environment, competitive breath-hold divers exhale to residual volume before diving in a swimming pool, thus compressing the chest even at depth of only 3–6 m. The study was undertaken to investigate whether such diving could cause pulmonary edema and hemoptysis. Eleven volunteer breath-hold divers who regularly dive on full exhalation performed repeated dives to 6 m during a 20-min period. The subjects were studied with dynamic spirometry, video-fibernasolaryngoscopy, and single-breath diffusion capacity of carbon monoxide (DlCO). The duration of dives with empty lungs ranged from 30 to 120 s. Postdiving forced vital capacity (FVC) was reduced from mean (SD) 6.57 ± 0.88 to 6.23 ± 1.02 liters ( P < 0.05), and forced expiratory volume during the first second (FEV1.0) was reduced from 5.09 ± 0.64 to 4.59 ± 0.72 liters ( P < 0.001) ( n = 11). FEV1.0/FVC was 0.78 ± 0.05 prediving and 0.74 ± 0.05 postdiving ( P < 0.001) ( n = 11). All subjects reported a (reversible) change in their voice after diving, irritation, and slight congestion in the larynx. Fresh blood that originated from somewhere below the vocal cords was found by laryngoscopy in two subjects. DlCO/alveolar ventilation (V̇a) was 1.56 ± 0.17 mmol·kPa−1·min−1·l−1 before diving. After diving, the DlCO/V̇a increased to 1.72 ± 0.24 ( P = 0.001), but 20 min later it was indistinguishable from the predive value: 1.57 ± 0.20 ( n = 11). Breath-hold diving with empty lungs to shallow depths can induce hemoptysis in healthy subjects. Edema was possibly present in the lower airways, as suggested by reduced dynamic spirometry.