Decompression Tables for Diving at Altitude

NCT03390335 | Completed

• 1 other identifier: Pro00087803
• Study Type: interventional
• Target: 103
• Locations: 1 country
• Sites: 1

Brief Summary

The aims of this proposal are to test current USN procedures for adjusting decompression procedures during air diving at 8,000 and 10,000 ft altitude and to provide a decompression algorithm for no-stop dives to 100 feet of sea water (fsw) at 10,000 and 12,000 ft altitude using enriched O2 (PO2=1.3 ATM). Additionally, the experiments will determine whether a period of hyperbaric hyperoxia, such as would be experienced during a dive at altitude, reverses altitude acclimatization, resulting in a return of acute mountain sickness (AMS) symptoms.

Conditions

Decompression Sickness; Acute Mountain Sickness

Outcome Measures

Primary Outcomes (2)

• Decompression Sickness

  Subjects will be evaluated for symptoms of decompression sickness when returning to the initial altitude following a dive exposure.

  12 hours

• Maximum Acute Mountain Sickness (AMS) Score Change

  Lake Louise Scoring System for Acute Mountain Sickness. Subjects will fill out a six-question questionnaire (0 - 3, higher scores are worse symptoms) and a three-question clinical assessment (0-4, 0-4, 0-2, higher score is worse a assessment). The total score of all questions and assessments (0 - 28, higher is worse AMS), is determined every eight hours for 48 hours at altitude pre-dive and 24 hours at altitude post-dive.

  48 hour, 72 hours

Secondary Outcomes (1)

• Venous Gas Emboli

  12 hours

Study Arms (1)

Altitude Dive Altitude profile

EXPERIMENTAL

Subjects are exposed to Pressure profiles (Altitude followed by a Dive with a return to Altitude) and Breathing Gases during dive exposures.

Other: Pressure; Other: Breathing Gas

Interventions

Pressure OTHER

Subjects undergo altitude exposure, diving exposure, and return to altitude. Altitudes: 8,000, 10,000, 12,000, or 15,000 feet Dives: 60 or 100 feet of sea water

Altitude Dive Altitude profile

Breathing Gas OTHER

Subjects will breathe air, 35% Oxygen, Balance Nitrogen, or 100% Oxygen during the diving exposure

Altitude Dive Altitude profile

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may not qualify if:

• smoking, cardiorespiratory disease (including hypertension, airways obstruction), seizure disorder, pregnancy, history of middle ear or sinus disease or high altitude cerebral or pulmonary edema (HACE, HAPE), inability to perform middle ear autoinflation, anemia, sickle cell disease and sickle cell trait. Individuals with VO2peak \<35 mL.kg-1.min-1 (males) and \<30 mL.kg-1.min-1 (females)

Sponsors & Collaborators

• Duke University: lead
• United States Department of Defense: collaborator

Study Sites (1)

Duke University Hospital

Durham, North Carolina, 27710, United States

Location

MeSH Terms

Conditions

Decompression Sickness; Altitude Sickness

Interventions

Pressure

Condition Hierarchy (Ancestors)

Barotrauma; Wounds and Injuries; Respiration Disorders; Respiratory Tract Diseases

Intervention Hierarchy (Ancestors)

Mechanical Phenomena; Physical Phenomena

Study Officials

• Richard Moon, MD

  Duke Universtiy Health System

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: SEQUENTIAL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: This design is a two factor, incomplete block design - three altitudes (8,000, 10,000, and 12,000 feet) and 2 breathing gases (air, 35% O2-N2). The investigators expect to see 0 events in the combinations tested, calculated by the Bayesian Method. If the rate of events is larger than expected, the investigators will use logistic regression to assess if the main effect Air (Air vs. 35% O2-N2) or altitude (8,000, 10,000 or 12,000 feet) or the interaction of these 2 factors imparts relative increased risk. The investigators will set a Type-I error rate of 0.05 (two-tailed).In the presence of 'zero cells', the investigators will either (1) collapse cells into reasonable groups, or (2) add a very small set of constants to the frequency and assess the impact on the effect sizes and tests of significance.1 In the absence of an interaction effect, main effects will be reported.

Study Record Dates

• First Submitted: December 28, 2017
• First Posted: January 4, 2018
• Study Start: February 13, 2018
• Primary Completion: October 29, 2021
• Study Completion: October 29, 2021
• Last Updated: December 14, 2021

Record last verified: 2021-11

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)