PURPOSE: It is well known that breath hold divers usuallly experience hemoptysis during diving. Since the transfer factor of carbon monoxide is the best marker to test the integrity of the blood-gas barrier, it was employed before and after diving in elicited breath hold-divers in order to search for any related changes.
METHODS: The study population consisted of 30 elicited divers (instructors), whose history of breath hold diving was more than 5 years at the time of the study, with personal limit above 50 meters. None of divers were current smokers neither reported cardiopulmonary diseases. All performed standard spirometry, lung volumes and single breath diffusing test according to the ERS-ATS guidelines. The experimental set-up was based on a series of dives progressively increased from 10 to 30 meters and performed during a national course of instrunctors for learning divers applying for the licence to dive. The single breath test manouvers were repeated immmediately after the last diving to 30 meters. Informed consent was regularly signed.
RESULTS: Nobody showed signs of airflow limitation neither of hyperinflation at baseline. Single breath diffusing indices were almost normal in all divers. When compared to the baseline values, the transfer factor measured immediately after the immersion showed a significant increase in all divers (more than 30% of the percent predicted). Most of the values returned back to the values recorded before diving in less than one hour. Alveolar volumes did not change.
CONCLUSION: This study showed that during diving to 30 meters there is a transient increase of the diffusing capacity. This finding, caused by the increase of intravascular blood volume and the consequent reduction of lung volumes, may suggest the presence of transient alveolar hemorrhage.
CLINICAL IMPLICATIONS: The continuous insults directed to lung during diving may be responsible of the rupture of the pulmonary capillaries.There is the need to increase the knowledge on the behaviour of the lung in this field and to study prospectically the outcome of these results in a cohort of divers.
DISCLOSURE: Renato Prediletto, None.