title: Preliminary observations on the effect of hypoxic and hyperbaric stress on pulmonary gas exchange in breath-hold divers.
abstract: OBJECTIVE
  To evaluate pulmonary alveolar-capillary membrane integrity and ventilation/perfusion mismatch after breath-hold diving.
  
  
  METHODS
  Pulmonary diffusing capacity to carbon monoxide (DLCO) and nitric oxide (DLNO), haemoglobin (Hb) and haematocrit (Hct) were measured in six elite divers before and at 2, 10 and 25 minutes after a maximal breath-hold dive to a depth of 10 metres' sea water.
  
  
  RESULTS
  Compared to pre-dive, DLCO showed a slight increase at 2 minutes in five subjects and a tendency to decrease at 25 minutes (P < 0.001) in all subjects. DLNO showed an increase at 10 minutes in three divers and a slight decrease at 25 minutes in five subjects. There was a small but significant (P < 0.001) increase in Hb and Hct at 2 minutes, possibly affecting the DLCO measurements.
  
  
  CONCLUSIONS
  An early but transient increase in DLCO in five divers may reflect the central shift in blood volume during a breath-hold dive. The late parallel decrease in DLCO and DLNO likely reflects alveolar-capillary distress (interstitial oedema). The DLNO increase in three subjects at 10 minutes may suggest ventilation/perfusion mismatch.
authors.affiliation: Extreme Center, Scuola Superiore, Sant'Anna and National Research Council-Tuscany Region "Gabriele Monasterio" Foundation, Pisa, Italy.
authors.forename: Erika
authors.initials: E
authors.lastname: Garbella
authors.forename: Andrea
authors.initials: A
authors.lastname: Piarulli
authors.forename: Edo
authors.initials: E
authors.lastname: Fornai
authors.forename: Alessandro
authors.initials: A
authors.lastname: Pingitore
authors.forename: Renato
authors.initials: R
authors.lastname: Prediletto
mesh_terms: D000328:Adult; D002248:Carbon Monoxide / Q000378:metabolism*; D004242:Diving / Q000502:physiology*; D005260:Female; D006400:Hematocrit; D006441:Hemoglobin A / Q000032:analysis; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D011653:Pulmonary Diffusing Capacity / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D013147:Spirometry
chemical_list: D009569:Nitric Oxide; D002248:Carbon Monoxide; D006441:Hemoglobin A