title: Variations in exhaled nitric oxide concentration after three types of dives.
abstract: BACKGROUND
  An increase in exhaled nitric oxide concentration (FENO) occurs during an exacerbation of chronic obstructive lung disease or other inflammatory processes of the airway. Raised FENO levels are also observed during normobaric, mild hyperoxic exposures, whereas after hyperbaric hyperoxic exposure the FENO level is reduced. This study investigated the variations of FENO after three different types of dives.
  
  
  METHODS
  Military divers participated in either a closed circuit rebreather dive (CCR, n = 17, pO2 = 130 kPa), semi-closed circuit rebreather dive (S-CCR, n = 12, pO2 = 180 kPa) or a compressed air dive (scuba, n = 17 pO2 = 126 or attendant, n = 12, pO2 = 118). Before and after each dive, the FENO was measured using a handheld electrochemical analyser (Niox Mino®).
  
  
  RESULTS
  All values for FENO feel within the normal range (5-25ppb). A small decrease in FENO level was found after all dives. After CCR dives FENO fell from 16.4 (± 8.0) pre-dive to13.6 (± 7.5) ppb, S-CCR from 16.2 (± 7.2) to 13.6 (± 6.3) ppb, scuba from 17.1 (± 5.6) to 16.1 (± 5.2) ppb and attendants from 17.7 (± 9.8) to 17.3 (± 9.1) ppb. Only after a CCR or S-CCR dive was this decrease statistically significant (P < 0.05).
  
  
  CONCLUSIONS
  In our divers, hyperbaric hyperoxia up to 180 kPa led to a small decrease in FENO in the conductive compartment of the lungs, the biological importance of which is unknown.
authors.affiliation: Senior diving medicine physician at the Diving Medical Centre, Royal Netherlands Navy, PO Box 10.000 1780 CA Den Helder, The Netherlands, Phone: +31-(0)223-653076, Fax: +31-(0)223-653148, E-mail: Pjam.v.ooij.01@mindef.nl.
authors.forename: Pieter-Jan
authors.initials: PJ
authors.lastname: van Ooij
authors.forename: Antoinette
authors.initials: A
authors.lastname: Houtkooper
authors.forename: Rob
authors.initials: R
authors.lastname: van Hulst