title: Nitric oxide and carbon monoxide diffusing capacity after a 1-h oxygen dive to 9 m of sea water.
abstract: BACKGROUND
  To prevent extensive pulmonary lesions in submerged oxygen divers lung function like the forced vital capacity (FVC) or the diffusing capacity for carbon monoxide (DL,co) are used to monitor pulmonary oxygen toxicity (POT). As the diffusing capacity for nitric oxide (DL,no) measures more accurately the membrane diffusing capacity compared to DL,co we hypothesized that DL,no is superior in monitoring the onset of physiological changes indicative of POT as compared to DL,co or FVC.
  
  
  METHODS
  26 healthy divers (mean age 30.7 ± 6.2 years) made two submerged dives to 190 kPa for 1 h on two randomized separate days, whilst breathing 100% oxygen or compressed air. FVC, DL,no, DL,co and alveolar volume (VA ) were measured 6 times during a 26-h period.
  
  
  RESULTS
  Up to 8 h no significant differences in outcomes were found between the oxygen and air dives. However, at 8 h after the oxygen dives there was a significant reduction in DL,no, DL,co and VA as compared with air dives. In contrast, the reduction in FVC was significantly greater after the air dive. At 22 h there were no longer differences in outcomes between the dives.
  
  
  CONCLUSIONS
  These data show that DL,no and DL,co are significantly reduced 8 h after submerged oxygen dives as compared to similar air dives. Together with the reduction in VA this may be indicative of interstitial edema as an early sign of POT. Our data warrant validation of the superiority of DL,no and DL,co over FVC in the practical monitoring of divers.
authors.affiliation: Diving Medical Center, Royal Netherlands Navy, Den Helder, Netherlands; Department of Respiratory Medicine, Academic Medical Centre, Amsterdam, Netherlands.
authors.forename: P J A M
authors.initials: PJ
authors.lastname: van Ooij
authors.forename: R A
authors.initials: RA
authors.lastname: van Hulst
authors.forename: A
authors.initials: A
authors.lastname: Houtkooper
authors.forename: P J
authors.initials: PJ
authors.lastname: Sterk
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D015415:Biomarkers / Q000097:blood; D002248:Carbon Monoxide / Q000097:blood*; D018592:Cross-Over Studies; D004242:Diving; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D018496:Hyperoxia / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D008168:Lung / Q000378:metabolism* / Q000503:physiopathology; D008176:Lung Volume Measurements; D008297:Male; D009569:Nitric Oxide / Q000097:blood*; D010100:Oxygen / Q000008:administration & dosage* / Q000009:adverse effects; D011237:Predictive Value of Tests; D011653:Pulmonary Diffusing Capacity; D012623:Seawater; D013147:Spirometry; D013997:Time Factors; D014797:Vital Capacity; D055815:Young Adult
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide; D002248:Carbon Monoxide; D010100:Oxygen
keywords: DL,CO; DL,NO; FVC; pulmonary oxygen toxicity; submersion