ORIGINAL RESEARCHES 233 www.journals.viamedica.pl Address for correspondence: Fariz Nurwidya, MD, PhD, FASPR, Department of Pulmonology and Respiratory Medicine, Faculty of Medicine Universitas Indonesia, Persahabatan Hospital, Jalan Persahabatan Raya No.1, Rawamangun Jakarta 13230, Indonesia, Tel. +62-21-489-3536, mobile: +62-812-8721-7858. Fax: +62-21-489-0744. Email: fariz.nurwidya@gmail.com DOI: 10.5603/ARM.2017.0038 Received: 21.03.2017 Copyright © 2017 PTChP ISSN 2451–4934 Muhammad Irfan Ilmi 1 , Faisal Yunus 1 , Mohammad Guritno Suryokusumo 2 , Triya Damayanti 1 , Erlang Samoedro 1 , Ahmad Muslim Nazaruddin 1 , Fariz Nurwidya 1 1 Department of Pulmonology and Respiratory Medicine, Faculty of Medicine Universitas Indonesia, Persahabatan Hospital, Jakarta, Indonesia 2 Division of Hyperbaric and Diving Health, Department of Community Medicine, Faculty of Medicine Universitas Indonesia, Jakarta, Indonesia Comparison of lung function values of trained divers in 1.5 ATA hyperbaric chamber after inhaling 100% oxygen and regular air: a crossover study The authors declare no financial disclosure Abstract Introduction: Diving is an activity performed in more than 1 atmosphere absolute pressure (ATA) either underwater or in a hy- perbaric chamber. We aimed to compare lung function values of trained divers in 1.5 ATA hyperbaric chambers after inhaling 100% oxygen and regular air. Methods: This experimental study with crossover design involved 18 trained divers in 1.5 ATA hyperbaric room, which is equiva- lent to a 5-meter depth. The eighteen subjects as the supplementation group, using oro-nasal mask, inhaled 100% oxygen for 30 minutes followed by a one-day washout period. The subjects were then crossed-over into control group inhaling only regular air for 30 minutes. Lung function test was performed before and after supplementation. Results: In eighteen subjects inhaling regular air, there was a signifcant difference (p < 0.05) in FEV 1 /FVC, PEF, FEF25, FEF50, and FEF75. Whereas in eighteen subjects inhaling 100% oxygen, signifcant difference (p < 0.05) was observed not only in FEV 1 /FVC, PEF, FEF25, FEF50 and FEF75, but also in FEV 1 . Conclusions: There were signifcant differences in lung function, especially in dynamic volume of trained divers in 1.5 ATA hyper- baric chamber after inhaling 100% oxygen and regular air for 30 minutes; while there were no signifcant differences in lung capa- city (VC and FVC) in the both groups. Lung function returned to normal following supplementation with a 1-day washout period. Key words: spirometry, ventilation, hyperbaric oxygenation, diving Adv. Respir. Med. 2017; 85: 233–238 Introduction Diving has been performed since ancient times for underwater works, but recently, pe- ople dive for recreation and sports, taking the advantage of the development of diving tech- nology that has allowed divers to get to places previously impossible to reach [1–4]. Diving is an activity performed in more than 1 atmos- phere absolute pressure either underwater or in a hyperbaric chamber, which affects body structure and function [5, 6]. Increase in unde- rwater environmental pressure is significant. Underwater pressure will increase by 100 kPa, which is equivalent to 1 atmosphere when di- vers descend as deep as 10 meters [1, 5]. The increase in pressure is followed by the increase in density of inhaled gas, which increases respi-