Inflammatory and Cerebrospinal Biochemical Markers in Blood After Trimix Diving (TriMix17-18)

March 8, 2019 updated by: Anders Rosén, Sahlgrenska University Hospital, Sweden

Biokemiska förändringar Vid förhöjt Partialtryck för Syrgas

Research hypothesis

  • Diving to depths up to 90msw with an oxygen partial pressure of 130kPa in the breathing gas will affect the central nervous system.
  • Diving to depths up to 90msw with an oxygen partial pressure of 130kPa in the breathing gas will induce inflammatory changes.

Objectives:

  • To investigate the presence of cerebrospinal biochemical markers in blood after diving to depths up to 90msw with an oxygen partial pressure of 130kPa in the breathing gas.
  • To investigate the presence of inflammatory markers in blood after diving to depths up to 90msw with an oxygen partial pressure of 130kPa in the breathing gas.
  • To investigate the presence of venous gas emboli (VGE) in blood after diving to depths up to 90msw with an oxygen partial pressure of 130kPa in the breathing gas.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

When diving with compressed air as breathing gas, a continuous accumulation of nitrogen will take place in the body. The total uptake of nitrogen by the tissues is dependent on the duration and depth of the performed dive. Decompression at the end of a dive can cause accumulated nitrogen to form intravascular bubbles.

Furthermore, at depths greater than 30 meters seawater (msw) the elevated partial pressure of nitrogen in the breathing gas will exert a direct effect on the nervous system. This is known as nitrogen narcosis and can cause altered cognitive function, confusion, behavioural disturbance and altered level of consciousness. The effect of nitrogen narcosis gets more pronounced with increasing diving depth. To avert nitrogen narcosis it is common to reduce the amount of nitrogen in the breathing gas being used. At the same time the amount of oxygen must also be reduced, as partial pressures of oxygen above 1,6kPa could induce seizures. Usually a breathing gas mixture containing helium, nitrogen and oxygen (TriMix) is used.

It has long been considered that decompression sickness (DCS) is caused by bubble formation when dissolved nitrogen at the end of diving comes out of solution. Doppler ultrasound techniques have shown that intravascular gas bubbles could exist even after uneventful dives. Therefore, additional pathophysiological factors must be sought.

There is evidence of an increased inflammatory activity in blood after diving. Signs of neutrophil activation is a common finding. It is not known if hyperbaric exposure in itself is enough to elicit these biochemical changes or if the presence of intravascular nitrogen bubbles is needed.

Studies have shown that biochemical markers of central nervous system (CNS) injury can be detected in blood samples obtained from patients with DCS, metabolic and neurologic disease, during cardiac surgery and after traumatic brain injuries. Such markers can also be seen in blood after sport activities like boxing and breath hold diving. If biochemical markers of CNS injury will be present in blood after hyperbaric exposure is not known.

The Swedish armed forces (SwAF) Diving and Naval Medicine Center (DNC) is responsible for education and training of divers for SwAF. The centre is also responsible for research and development and conduct tests for diving medicine, and tests of underwater equipment.

SwAF DNC will during 2017 and 2018 be responsible for naval dive training including deep dives (up to 90 msw) using TriMix as breathing gas. The partial pressure of oxygen will be kept at 130kPa. The study "Inflammatory and cerebrospinal biochemical markers in blood after TriMix diving - an observational controlled study" will be followed out during these tests. It entails venous blood sampling and cardiac ultrasound.

This is a prospective, controlled observational study (see addendum 08/03/19 below). The study aims to involve at least 16 study subjects. Half of the subjects (at least 8 persons), named the intervention group, dive to depths up to 90msw with an oxygen partial pressure of 130kPa in the TriMix breathing gas. Half of the subjects (at least 8 persons), named the control group, do not dive. The dives are part of the Swedish navy´s training programme for TriMix diving.

Blood samples are obtained from the intervention group before and after diving (two tubes and about 8mL of blood each time, in total 16mL of blood). If possible, a third blood sample are taken about 24 hours after the first sample. Blood samples are obtained from the control group at the same time points as from the intervention group.

Immmediately after diving, cardiac ultrasound will be used to assess presence and duration of VGE in the intervention group.

Signs of DCS will be actively sought.

Addendum 08/03/19: A control group containing non-diving military divers was initially planned. However, difficulties in subject recruitment meant that an appropriate control group could not be formed. It was performed as an observational study without controls.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
10

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Sweden
      • Gothenburg, Sweden, S-405 30
        • Gothenburg University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 60 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Military divers and individuals approved by the Swedish navy to dive or perform work in hyperbaric environment.

Description

Inclusion Criteria:

- Military diver or individual approved by the Swedish navy to dive or perform work in hyperbaric environments

Exclusion Criteria:

- As this is a highly selected population there is no exclusion criteria

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Cohort
  • Time Perspectives: Prospective

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Trimix
Exposure to ambient pressure of maximum 11 ATA breathing Trimix. Exposure to oxygen partial pressure of 130 kPa breathing Trimix.
Other: Exposure to oxygen partial pressure of 130 kPa
Open sea diving to a maximum depth of 100 msw while breathing Trimix.
Other: Exposure to ambient pressure of maximum 11 ATA
Open sea diving to a maximum depth of 100 msw while breathing Trimix.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Concentration of cerebrospinal and inflammatory biochemical markers in blood
Time Frame: Three months
E.g. GFAP, Tau, NfL, JCHL-1, VCAM-1, ICAM-1
Three months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Presence of Venous Gas Emboli (VGE)
Time Frame: Five days
Kisman-Masurel grading
Five days
Decompression Sickness (DCS)
Time Frame: Five days
Clinical diagnosis
Five days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Sahlgrenska University Hospital, Sweden

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Göteborg University
KTH Royal Institute of Technology
Swedish Armed Forces Diving and Naval Medicine Centre

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 12, 2017

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 30, 2019

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 30, 2019

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
June 14, 2017

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 14, 2017

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
June 16, 2017

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 12, 2019

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 8, 2019

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2019

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • EPN 292-17

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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