title: Hypobaric Decompression Sickness Treatment Model.
abstract: BACKGROUND
  The Hypobaric Decompression Sickness (DCS) Treatment Model links a decrease in computed bubble volume from increased pressure (ΔP), increased oxygen (O2) partial pressure, and passage of time during treatment to the probability of symptom resolution [P(SR)]. The decrease in offending volume is realized in two stages: 1) during compression via Boyles law; and 2) during subsequent dissolution of the gas phase via the oxygen window.
  
  
  METHODS
  We established an empirical model for the P(SR) while accounting for multiple symptoms within subjects. The data consisted of 154 cases of hypobaric DCS symptoms with ancillary information from tests on 56 men and 18 women.
  
  
  RESULTS
  Our best estimated model is P(SR)=1/(1+exp(-(ln(ΔP)-1.510+0.795×AMB-0.00308×Ts)/0.478)), where ΔP is pressure difference (psid); AMB=1 if ambulation took place during part of the altitude exposure, otherwise AMB=0; and Ts is the elapsed time in minutes from the start of altitude exposure to recognition of a DCS symptom.
  
  
  CONCLUSIONS
  Values of ΔP as inputs to the model would be calculated from the Tissue Bubble Dynamics Model based on the effective treatment pressure: ΔP=P2-P1|=P1×V1/V2-P1, where V1 is the computed volume of a bubble at low pressure P1 and V2 is computed volume after a change to a higher pressure P2. If 100% ground-level oxygen was breathed in place of air, then V2 continues to decrease through time at P2 at a faster rate.
authors.affiliation: Universities Space Research Association, Houston, TX, USA.
authors.forename: Johnny
authors.initials: J
authors.lastname: Conkin
authors.forename: Andrew F J
authors.initials: AF
authors.lastname: Abercromby
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Dervay
authors.forename: Alan H
authors.initials: AH
authors.lastname: Feiveson
authors.forename: Michael L
authors.initials: ML
authors.lastname: Gernhardt
authors.forename: Jason R
authors.initials: JR
authors.lastname: Norcross
authors.forename: Robert
authors.initials: R
authors.lastname: Ploutz-Snyder
authors.forename: James H
authors.initials: JH
authors.lastname: Wessel
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D018480:Astronauts; D003665:Decompression Sickness / Q000378:metabolism / Q000503:physiopathology* / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D010100:Oxygen / Q000097:blood / Q000378:metabolism; D010313:Partial Pressure; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D010100:Oxygen