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

NCT ID: NCT02468752

Last Updated: 2022-05-27

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

PHASE2/PHASE3

Total Enrollment

48 participants

Study Classification

INTERVENTIONAL

Study Start Date

2015-05-31

Study Completion Date

2019-04-30

Brief Summary

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Primary objective:

\- Assessment of venous gas emboli load post diving when breathing normobaric oxygen compared to air.

Secondary objective:

* Assessment of fluid markers of central nervous system injury in blood post diving
* Assessment of fluid markers of inflammation and endothelial dysfunction in blood post diving

Tertiary objective:

\- Assessment of DCS frequency

Detailed Description

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This is a prospective, double blinded, randomized, cross-over study in Sweden. The study was performed in two different sets, each containing standardized dives in a wet hyperbaric chamber. The dives included movement on depth.

In each study set 16-32 professional divers performed no-decompression dives to a depth of 42 metres of seawater (msw). The gas used during the dives was compressed air.

After surfacing the divers breathed either normobaric oxygen or normobaric air on a demand mask. Timing of oxygen/air-breathing differed between study sets. The content of breathing gas was unknown to both divers and examining personnel.

Immediately post dive the divers were assessed using either transthoracic doppler ultrasound (TTD) or transthoracic 2-D ultrasound (TTE) to determine VGE load, time to VGE detection and VGE duration.

Signs of DCS were actively sought.

TTD measurements were done every five minutes during the first 30 minutes, thereafter every 15 minutes during 90 minutes.

TTE was performed every 30 minutes, using an apical 4-chamber view.

Blood samples were obtained pre-dive, 30-45 minutes post-dive and 120 minutes post-dive.

Set 1: 16 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. Immediately post dive breathing of oxygen (group A) or air (group B) during 30 min. VGE load, time to VGE detection and VGE duration is recorded. Blood samples were obtained pre-dive and 30 and 120 minutes post-dive. After 48 hours, the dives were repeated with switched gases between the groups.

Set 2: 32 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. Fifteen minutes post dive breathing of oxygen (group A) or air (group B) during 30 min. VGE load, time to VGE detection and VGE duration is recorded. Blood samples were obtained pre-dive and 45 and 120 minutes post-dive, from the first 16 divers. After 48 hours, the dives were repeated with switched gases between the groups.

Two further planned sets with repeated diving and shorter duration of oxygen/air-breathing were never carried through.

AE including SAE will be recorded during the study. DCS may be considered either an AE or SAE depending on severity. Ongoing AE and SAE will be followed up.

Conditions

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Hyperbaric Diving Medicine Decompression Sickness Central Nervous Injury Inflammation Endothelial Dysfunction

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

CROSSOVER

Primary Study Purpose

PREVENTION

Blinding Strategy

TRIPLE

Participants Caregivers Investigators

Study Groups

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Air

Normobaric air breathing

Group Type SHAM_COMPARATOR

Air

Intervention Type OTHER

Oxygen

Normobaric oxygen breathing

Group Type EXPERIMENTAL

Oxygen

Intervention Type DRUG

Interventions

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Oxygen

Intervention Type DRUG

Air

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Professional diver
* Fit to dive according to Swedish Navy standards

Exclusion Criteria

* NONE
Minimum Eligible Age

18 Years

Maximum Eligible Age

65 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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Swedish Armed Forces Diving and Naval Medicine Centre

OTHER

Sponsor Role collaborator

KTH Royal Institute of Technology

OTHER

Sponsor Role collaborator

Sahlgrenska University Hospital

OTHER

Sponsor Role collaborator

Göteborg University

OTHER

Sponsor Role lead

Responsible Party

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Nicklas Oscarsson

MD

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Mikael Gennser, PhD

Role: PRINCIPAL_INVESTIGATOR

Kungliga Tekniska Högskolan, Stockholm, Sweden

Locations

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Sahlgrenska University Hospital

Gothenburg, , Sweden

Site Status

Kungliga Tekniska Högskolan

Stockholm, , Sweden

Site Status

Countries

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Sweden

Other Identifiers

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DYK 14-16

Identifier Type: -

Identifier Source: org_study_id

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