Clinical Trial: Reduction of Venous Emboli Load After Breathing Normobaric Oxygen Compared to Air

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title:

Brief Summary:

The primary objective of this study is to assess venous gas emboli load post diving when breathing normobaric oxygen compared to air.

The secondary objectives are

  • Assessment of DCS frequency
  • Comparison of TCD and TTD consistency in venous gas emboli measurements
  • Inflammatory activity in blood post diving

Detailed Summary:

3.1 Overall study design and flow chart This is a prospective, double blinded, randomized and controlled, cross-over study in Sweden.

The study will be performed in three different sets, each containing identical standardized dives. The dives include movement on depth. Dive-computers will be used.

In each pair of dives 10-20 professional divers from the Swedish navy will perform no-decompression dives. If multiple dives are performed during one day, there will be an appropriate adjustment of dive depth and time, according to established Swedish navy standards. The gas used during the dives is compressed air.

After surfacing the divers will breathe (15 L/min) either normobaric oxygen or normobaric air during 15-30 minutes, depending on study set. Both oxygen and air will be administered using a free-flowing mask. The content of the gas containers will be unknown to both divers and examining personnel.

Immediately post dive the divers will be assessed using TTD, TTE or TCD to determine VGE load, time to VGE detection and VGE duration. In Set 3 measurements will be done after the second dive. The subjects will avoid strenuous activities during the examination period and between dives in Set 3.

Signs of DCS will be actively sought. TTD measurements will be done every five min during the first 30 min, thereafter every 15 min during 90 min.

TTE will be performed every 30 min, using an apical 4-chamber view. TCD measurements are done continuously.

Set 1: 10-20 divers, divided into two equal groups (A and B). Dive to 42 msw during 10 min with a safety stop at five msw during three min.
Sponsor: Göteborg University

Current Primary Outcome: Venous gas emboli [ Time Frame: 150 minutes ]

Original Primary Outcome: Same as current

Current Secondary Outcome:

  • Inflammatory activity [ Time Frame: 150 minutes ]
    Biomarkers
  • Decompression sickness [ Time Frame: 24 hours ]
  • Correlation of bubble load between Transcranial doppler and Transthoracic doppler [ Time Frame: 150 minutes ]
    Quantification of bubble load after dive with transthoracic doppler and transcranial doppler. We will investigate if there is any correlation between the two modalities. Bubble load are measured using a standardized scale (0-4) for each heart beat.


Original Secondary Outcome: Same as current

Information By: Göteborg University

Dates:
Date Received: June 3, 2015
Date Started: May 2015
Date Completion:
Last Updated: February 22, 2017
Last Verified: February 2017