Oxygen-Enriched Air: Is It Bad for the Diver?

Home , Nitrox, Paul Bert

Oxygen-Enriched Air: Is it bad for the diver? Zenske A1, Schipke JD 2, Kähler W3, Koch A3, Stirban A4, Krüll M5 1Klinikum Landshut, Landshut & Charité, Berlin, 2University Hospital Düsseldorf, Research Group SchiffMedInst, Kiel Experim. Surgery, Düsseldorf, 3SchiffMedInst der Marine, Kiel, 4Profil, Metabolic Research Institute, Neuss, 5Medical Institute Berlin-Marathon & Charité, Berlin

Background Results Discussion

While SCUBA diving, the increasing 1. Pulmonary function Already in 1878, Paul Bert investigated ambient pressure increases pO 2 in Nitrox and described its potential toxicity parallel with increasing depth. Usage of (O-radicals; oxidative stress). oxygen enriched air (=Nitrox) as breathing gas, additionally increases pO 2 and Nitrox is increasingly used by recreational thus, oxidative stress. On the other hand, divers, in particular by dive guides. Thus, pN 2 is decreased with Nitrox, thereby possible harmful effects could become decreasing potential narcotic N 2 effects. more relevant.

Until now, predominantly O 2 effects on Aim of study CNS and lungs were investigated. We suggest to also address other organs like Investigate whether increasing O 2 and Fig. 1: Diving with either breathing gas left skeletal and cardiac muscle, blood and the reducing N 2 exerts effects on total pulmonary resistance unchanged but eyes, as oxidative stress likely induces (1) pulmonary function, lead to an increase of the peripheral pulmo- injury in all cell types. (2) elastic properties of blood vessels, nary resistance (AX): air: +9 %, Nx40: 19 %. (3) cognitive competence, and With the advent of newer measuring (4) bubble formation. devices, more subtle aspects (peripheral 2. Reactive hyperemia (RH) pulmonary resistance) and/or other aspects (RH) were investigated in this study. Volunteers & Methods Luft; max. Blutstrom Nx40; max. Blutstrom 160 160 Our results suggest that the increased oxidative stress impairs small pulmonary 25 divers (~40 ys) performed one dive 120 120 airways as well as the vascular com- with air and another with Nitrox40 (i.e. 80 80 pliance. On the other hand, cognitive ~60 % N 2 and 40 % O 2). Maximum depth 40 40 competence is better preserved with less was 25 m, and dive time was 40 min. narcotic N 2-effects and less N 2-bubbles are 0 0 Before and after the dive, pulmonary vor nach vor nach formed (see table). function (MasterScreen-IOS, CareFusion; Nitrox40 Fig. 2: RH after air remained unchanged but top, left) and reactive hyperemia (RH) Lungs peripheral resistance was reduced by 29.5% after Nx40 measured with Laser-Doppler (Peri- Blood vessels dilatative capacity flux5000, Perimed; top, right) were Cognition memory / alertness ☺ assessed. 3. Cognitive competence N2-bubbles bubble trouble ☺ Cognitive competence (memory; after Helmstaedter C, VLMT-A 2001 & Conclusion alertness; Oswald WD, Roth E; ZVT-A; 1970; bottom, left) was assessed during the dive, and bubbles in the internal Under the conditions of this study, jugular vein (Doppler; bottom, right) were Nitrox40 exerts both advantages and counted 30, 60, and 90 min after the end disadvantages. As disadvantages of the dive. might accumulate over time, dive Fig. 3: Nx40 improved memory and alertness. pauses should be allowed for injured organic tissue to recover. 3. Bubble trouble

150 Acknowledgements 120 Pulmonary function, Spirometry / Oscillometry 90 HJ Smith; Fa. Care Fusion, Höchberg 60 Bubble formation, Prof. A Salm, Esslingen Summe Blasen Summe 30 Training Centre for Trimix & Mixed Gas Diving, 0 Timo Zischka, Geretsried 30 min 60 min 90 min

Fig. 4: Nx40 reduced bubble formation by Sponsor 15 % (30 min) and 50 % (60 min). Bubble amount peaked at 60 min relatively late GTÜM, German Society for Diving after end of dive and Hyperbaric Medicine, Murnau 93. Annual Meeting of the DPG, Mainz 2014