Oxygen Toxicity: Mechanisms in Humans

Part of paid clinical trials in Durham, North Carolina.

Sponsor
Duke University
Study ID
NCT05761756
Status
Recruiting
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Conditions

  • Hypercapnia
  • Oxygen Toxicity
  • Seizures

Eligibility Criteria

Sex
ALL
Age
18 Years - 45 Years
Healthy Volunteers
Accepted

Interventions

  • Sleep Deprivation — BEHAVIORAL
    24 hours sleep deprivation
  • Caffeine — DRUG
    Oral administration of caffeine
  • Methylphenidate — DRUG
    Oral administration of methylphenidate
  • Carbon Dioxide — DRUG
    Oral administration of sodium bicarbonate to simulate carbon dioxide exposure

Study Details

The goal of this clinical trial is to learn about the mechanisms of oxygen toxicity in scuba divers. The main questions it aims to answer are: * How does the training of respiratory muscles affect oxygen toxicity? * How do environmental factors, such as sleep deprivation, the ingestion of commonly utilized medications, and chronic exposure to carbon dioxide, impact the risk of oxygen toxicity? * How does immersion in water affect the development of oxygen toxicity? Participants will be asked to do the following: * Undergo a basic screening exam composed of health history, vital signs, and some respiratory function tests * Train their respiratory muscles at regular intervals * Exercise on a cycle ergometer both in dry conditions and underwater/under pressure in the context of medication, sleep deprivation, or carbon dioxide exposure Researchers will compare the performance of each subject before and after the possible interventions described above to see if there are changes in exercise performance, respiratory function, cerebral blood flow, and levels of gene expression.

Key Dates

Start date
Nov 28, 2023
Status verified
Oct 2025
Primary completion
Aug 31, 2026
Completion
Aug 31, 2026

Study Design

Enrollment
62 participants (estimated)
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION

Arms

  • Active Comparator: Sleep Deprivation
    Effect of sleep deprivation on HCVR and arterial PCO2 during submersed rest and exercise at 98 fsw. Ten subjects will be tested before and after 24 hours of sleep deprivation. The order of sleep deprivation vs. control will be randomized. Measurements at 98 fsw will be obtained at rest and during 10 minutes of moderate exercise in thermoneutral (29-30°C) water.
  • Experimental: Caffeine
    Effect of caffeine and methylphenidate on HCVR and arterial PCO2 during submersed rest and exercise at 98 fsw. Twenty subjects will be similarly sleep-deprived, tested as above and then re-tested tested following oral administration of administration of either oral caffeine (N=10) or methylphenidate (N=10). Pre-dive caffeine will be administered 500 mg orally \[59\]. Pre-dive methylphenidate will be administered as a single dose of 5 mg \[60\]. The order of drug administration vs. control will be randomized. Measurements at 98 fsw will be obtained at rest and during 10 minutes of moderate exercise in thermoneutral (29-30°C) water. fNIRS will be used to assess cerebral oxygenation and regional blood volume.
  • Experimental: Methylphenidate
    Effect of caffeine and methylphenidate on HCVR and arterial PCO2 during submersed rest and exercise at 98 fsw. Twenty subjects will be similarly sleep-deprived, tested as above and then re-tested tested following oral administration of administration of either oral caffeine (N=10) or methylphenidate (N=10). Pre-dive caffeine will be administered 500 mg orally \[59\]. Pre-dive methylphenidate will be administered as a single dose of 5 mg \[60\]. The order of drug administration vs. control will be randomized. Measurements at 98 fsw will be obtained at rest and during 10 minutes of moderate exercise in thermoneutral (29-30°C) water. fNIRS will be used to assess cerebral oxygenation and regional blood volume.
  • Experimental: Carbon Dioxide Exposure
    Effect of simulated chronic CO2 exposure on HCVR and arterial PCO2 during submersed rest and exercise at 98 fsw. Ten subjects will be studied before and after induction of metabolic alkalosis as described above with daily oral administration of sodium bicarbonate. Oral bicarbonate to simulate hypercapnia exposure will seek to increase serum bicarbonate to 30 mM/L via daily oral intake of 6 teaspoons of NaHCO3 for five days. Subsequently, blood will be drawn and intake adjusted as necessary \[61\]. The order of alkalization vs. control will be randomized. Measurements at 98 fsw will be obtained at rest and during 10 minutes of moderate exercise in thermoneutral (29-30°C) water.

Primary Outcome Measure

Hypercapnic ventilatory response [ Time Frame: 3 months ]

Central Contacts

Locations (1)

FacilityCityStateZIPSite coordinators
Duke University Health SustemDurhamNorth Carolina27705
Derek Covington, M.D.
[email protected]
919-613-8881

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