Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Decompression at 1.3 versus 1.6 bar and Nitrogen Elimination and Venous Gas Emboli : A Randomized Controlled Trial

Plogmark, Oscar LU ; Hjelte, Carl LU orcid ; Olsson, Max LU orcid ; Ekström, Magnus LU orcid and Frånberg, Oskar LU (2025) In Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc 52(4). p.577-585
Abstract

INTRODUCTION: The optimal depth for decompression stops is unclear. We hypothesize that a decompression stop at 1.3 bar, compared with 1.6 bar, decreases post-dive whole-body nitrogen washout volumes and venous gas emboli (VGE).

METHODS: In this randomized crossover trial, divers performed wet air dives of 40 minutes at 3.4 bar (340 kPa) with a seven-minute-long decompression stop at either 1.3 bar (Deco 1.3) or 1.6 bar (Deco 1.6) in randomized order. The primary outcome was the difference in post-dive whole body nitrogen washout volume, analyzed using multilevel linear regression. The secondary outcome was the difference in peak VGE detected by cardiac two-dimensional ultrasound, graded using the Eftedal-Brubakk scale, and... (More)

INTRODUCTION: The optimal depth for decompression stops is unclear. We hypothesize that a decompression stop at 1.3 bar, compared with 1.6 bar, decreases post-dive whole-body nitrogen washout volumes and venous gas emboli (VGE).

METHODS: In this randomized crossover trial, divers performed wet air dives of 40 minutes at 3.4 bar (340 kPa) with a seven-minute-long decompression stop at either 1.3 bar (Deco 1.3) or 1.6 bar (Deco 1.6) in randomized order. The primary outcome was the difference in post-dive whole body nitrogen washout volume, analyzed using multilevel linear regression. The secondary outcome was the difference in peak VGE detected by cardiac two-dimensional ultrasound, graded using the Eftedal-Brubakk scale, and analyzed with Wilcoxon matched-pairs signed-rank tests.

RESULTS: Sixteen divers completed both Deco 1.3 and Deco 1.6. Post-dive whole body nitrogen washout volumes were measured in eight of the 16 participants and were lower with Deco 1.3 than Deco 1.6 (696 ml [95% confidence interval [CI], 601 to 790] versus 1068 ml [95% CI, 962 to 1174]), mean difference of 373 ml (95% CI, 243 to 502). Deco 1.3 had lower peak bubble grades than Deco 1.6 (interquartile range 2-3 versus 3-4; P=0.005), but the median grade was the same at 3.

CONCLUSIONS: Decompression stop at 1.3 bar instead of 1.6 bar decreased post-dive whole body nitrogen washout volume and VGE. These findings may inform the development of future decompression models.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Humans, Embolism, Air/prevention & control, Nitrogen/metabolism, Male, Diving/physiology, Adult, Decompression/methods, Cross-Over Studies, Female, Time Factors, Decompression Sickness/prevention & control, Middle Aged, Ultrasonography, Linear Models
in
Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc
volume
52
issue
4
pages
577 - 585
publisher
Undersea and Hyperbaric Medical Society
external identifiers
  • scopus:105025600471
  • pmid:41429035
ISSN
1066-2936
language
English
LU publication?
yes
additional info
Copyright© Undersea and Hyperbaric Medical Society.
id
aa1765cf-af6b-4582-b926-652f519062f1
alternative location
https://www.uhms.org/uhm-search/uhm-journal-volume-52-2025/number-4/815.html
date added to LUP
2026-02-16 09:01:25
date last changed
2026-02-17 04:00:26
@article{aa1765cf-af6b-4582-b926-652f519062f1,
  abstract     = {{<p>INTRODUCTION: The optimal depth for decompression stops is unclear. We hypothesize that a decompression stop at 1.3 bar, compared with 1.6 bar, decreases post-dive whole-body nitrogen washout volumes and venous gas emboli (VGE).</p><p>METHODS: In this randomized crossover trial, divers performed wet air dives of 40 minutes at 3.4 bar (340 kPa) with a seven-minute-long decompression stop at either 1.3 bar (Deco 1.3) or 1.6 bar (Deco 1.6) in randomized order. The primary outcome was the difference in post-dive whole body nitrogen washout volume, analyzed using multilevel linear regression. The secondary outcome was the difference in peak VGE detected by cardiac two-dimensional ultrasound, graded using the Eftedal-Brubakk scale, and analyzed with Wilcoxon matched-pairs signed-rank tests.</p><p>RESULTS: Sixteen divers completed both Deco 1.3 and Deco 1.6. Post-dive whole body nitrogen washout volumes were measured in eight of the 16 participants and were lower with Deco 1.3 than Deco 1.6 (696 ml [95% confidence interval [CI], 601 to 790] versus 1068 ml [95% CI, 962 to 1174]), mean difference of 373 ml (95% CI, 243 to 502). Deco 1.3 had lower peak bubble grades than Deco 1.6 (interquartile range 2-3 versus 3-4; P=0.005), but the median grade was the same at 3.</p><p>CONCLUSIONS: Decompression stop at 1.3 bar instead of 1.6 bar decreased post-dive whole body nitrogen washout volume and VGE. These findings may inform the development of future decompression models.</p>}},
  author       = {{Plogmark, Oscar and Hjelte, Carl and Olsson, Max and Ekström, Magnus and Frånberg, Oskar}},
  issn         = {{1066-2936}},
  keywords     = {{Humans; Embolism, Air/prevention & control; Nitrogen/metabolism; Male; Diving/physiology; Adult; Decompression/methods; Cross-Over Studies; Female; Time Factors; Decompression Sickness/prevention & control; Middle Aged; Ultrasonography; Linear Models}},
  language     = {{eng}},
  number       = {{4}},
  pages        = {{577--585}},
  publisher    = {{Undersea and Hyperbaric Medical Society}},
  series       = {{Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc}},
  title        = {{Decompression at 1.3 versus 1.6 bar and Nitrogen Elimination and Venous Gas Emboli : A Randomized Controlled Trial}},
  url          = {{https://www.uhms.org/uhm-search/uhm-journal-volume-52-2025/number-4/815.html}},
  volume       = {{52}},
  year         = {{2025}},
}