Oxygen ToxicityNCT05831228
Effects of Pre-dive Ketone Food Products on Latency to CNS Oxygen Toxicity (Aim 2)
A study testing Ketogenic food products in people with Oxygen Toxicity, run by Duke University at 1 site in United States.
Trial summary
The purpose of this study is to understand how ketogenic food products affect oxygen toxicity in undersea divers. Oxygen toxicity affecting the central nervous system, mainly the brain, is a result of breathing higher than normal oxygen levels at elevated pressures as can be seen in SCUBA diving or inside a hyperbaric… Read more about this study
- Who is it for?
- Ages 18 to 39 yearsHealthy volunteers can take part
- Conditions the study is for
- Oxygen Toxicity
- What is being tested?
- Ketogenic food products
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 20 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Sep 2023to 31 Mar 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 39 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Males \& females between 18 and 39 years old.
- Measured (Phase 2) VO2max ≥ 30 ml/kg/min (female) or 35 ml/kg/min (male).
- BMI ≤ 30.0 unless VO2max and baseline exercise profile is deemed appropriate for the study by the PI.
- (Phase 2 only) Able to exercise continuously on cycle ergometer for 2 hours.
- (Phase 2 only) Able to equalize middle ears and tolerate hyperbaric chamber exposure test.
Who cannot join
- Prolonged QTc on initial ECG
- Currently pregnant or attempting to become pregnant.
- Have a medical history of:
- Smoking history deemed significant by PI
- Known significant electrolyte disorders
- Coronary artery disease
Show all 19Show fewer
- Cardiac arrhythmia deemed significant by PI
- Lung disease
- Hypertension
- Seizures
- Exercise intolerance or inability to meet inclusion requirements
- Psychiatric disorder deemed significant by PI
- Previous pneumothorax or pneumomediastinum
- Hypo- or hyperglycemia
- Diabetes
- Inability to equalize middle ear spaces during hyperbaric compression
- Claustrophobia
- Regularly take any medications which may alter heart rate, blood pressure, neurotransmitter function, alter seizure threshold, mood or affect per PI discretion.
- Any other condition limiting ability to perform exercise testing or dive profile as determined by the investigators.
Trial locations and contacts
1 site in 1 country.
United States1 site
Duke University Hospital
Durham, North Carolina, 27710
About this study
Official title: Effects of Pre-dive Ketone Food Products on Latency to Central Nervous System Oxygen Toxicity
The purpose of this study is to understand how ketogenic food products affect oxygen toxicity in undersea divers. Oxygen toxicity affecting the central nervous system, mainly the brain, is a result of breathing higher than normal oxygen levels at elevated pressures as can be seen in SCUBA diving or inside a hyperbaric (pressure) chamber. This is a condition that may cause a wide variety of symptoms such as: vision disturbances, ear-ringing, nausea, twitching, irritability, dizziness, and potentially loss of consciousness or seizure. Because nutritional ketosis has been used to reduce or eliminate seizures in humans, it may be beneficial to reduce oxygen toxicity as well. The investigators hope this study will provide a help to develop practical and useful methods for improving the safety of undersea Navy divers, warfighters and submariners.
Read the detailed description
Central nervous system (CNS) oxygen toxicity continues to be a risk for military divers and constrains their operations. Manifestations of this condition range from nausea, twitching, and tinnitus to seizures and unresponsiveness, and the latter may lead to death by drowning. The NAVY has a need for better methods to prevent or delay the onset of CNS oxygen toxicity (CNSOT) and to safely expand the scope of diving operations. It is the broad objective of this study to generate information that will enhance warfighter safety and performance in relevant NAVY operations by reducing the risk of CNS oxygen toxicity.
It is known that nutritional ketosis through a diet with a high fat-to-carbohydrate ratio (ketogenic diet) can reduce the frequency and severity of epileptic seizures in humans, and a recent animal study has shown that dietary ketosis also delays the onset of CNSOT. In recent years, ketone ester food products ketone esters have been made commercially available which may elevate circulating ketone levels. The investigators aim to investigate whether ketosis from commercially available ketogenic food products prior to a dive will delay the onset of CNSOT.
The first aim of this study will be to determine the effect of ketone food product ingestion on serum ketone levels, and document any relevant side effects. Post-ingestion ketone levels will be trended for 3 different ketone food product regimens in 15 total subjects. Data will be used to select the optimal ketone food product strategy to investigate in the second aim.
This second aim will be to evaluate the primary hypothesis, that pre-dive ketone food products will prolong latency to CNSOT. To assess this, 20 subjects will be studied in a randomized, controlled, double-blind, crossover methodology. After consuming either the ketone food product or placebo, each subject will complete an immersed, head out hyperbaric oxygen exposure while exercising on an underwater cycle ergometer at 2.06 ATA (35 fsw) until oxygen toxicity symptoms develop or the maximum time limit of 120 minutes is reached. The experiment will be repeated on a different day by each subject after consuming the opposite (ketone food products or placebo). Primary outcome will be time to manifestation of CNSOT. Physiologic monitoring throughout the study will provide secondary endpoints such as cognitive performance, sympathetic nervous system stimulation via electrodermal activity, electroencephalography, cardiorespiratory measures and end-tidal CO2/O2/N2; all adding to our understanding of CNSOT physiology which may guide future mitigation and monitoring strategies.
- Conditions
- Oxygen Toxicity
- Being tested
- Ketogenic food products, Control: Placebo
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Ketogenic food productsDietary supplement
Participants will be given a ketogenic food product prior to the hyperbaric oxygen exposure.
Control: PlaceboDietary supplement
Participants will be given a dietary supplement comparator prior to the hyperbaric oxygen exposure.
| Study group | Role | What they receive |
|---|---|---|
| Experimental: Ketogenic food products | Experimental | Dietary Supplement: Ketogenic food products Participants will be given a ketogenic food product prior to the hyperbaric oxygen exposure. Receives: Dietary Supplement: Ketogenic food products |
| Control: Placebo | Placebo comparator | Dietary Supplement comparator Receives: Dietary Supplement: Control: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Latency to central nervous system oxygen toxicity (CNSOT)
Assessment of latency to CNSOT in a simulated working dive breathing 100% oxygen at 2.06 ATA, immersed in water (head out), in a hyperbaric chamber while performing exercise. Endpoint is time to development of signs or symptoms of CNSOT. Maximum duration 120 minutes.
Measured: 2 hours
Secondary outcomes (9)
Cognitive performance
Changes in Multi Attribute Test battery scores prior to and during hyperbaric exposure. Tracking score pixel distance from target center, scale min = 0, no defined maximum.
Measured: Day 1
Level of nutritional ketosis as detected by serume beta hydroxybutyrate levels
Measure serume beta hydroxybutyrate levels in blood samples
Measured: Day 1
Number of participants with change in EEG
Changes in visual EEG inspection prior to and during hyperbaric exposure.
Measured: Day 1
Change in qEEG alpha/delta power ratio (ratio of power in alpha frequency band to power in delta frequency band)
Changes in qEEG readings prior to and during hyperbaric exposure
Measured: Day 1
Change in end-tidal CO2
Changes in end-tidal CO2 levels in blood samples prior to and during hyperbaric exposure
Measured: Day 1
Change in venous CO2
Changes in CO2 levels in blood samples prior to and during hyperbaric exposure
Measured: Day 1
Change in heart rate
Changes in heart rate prior to and during hyperbaric exposure
Measured: Day 1
Change in ventilatory rate
Changes in ventilatory rate prior to and during hyperbaric exposure
Measured: Day 1
Number of participants who develop CNS oxygen toxicity
Any symptoms of CNSOT during hyperbaric exposure as described by participants will be recorded.
Measured: Day 1
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Apr 2023
- Study start1 Sep 2023
- Primary completion31 Mar 2025
- Study completion31 Mar 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Oxygen ToxicityStudies of the same condition, open and under way.
- More trials run by Duke UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- Duke University
- Sponsor type
- University, hospital or other
- Collaborators
- United States Navy
- Responsible party
- Sponsor
- Investigators
- Bruce Derrick, MD, Principal investigator, Duke Health
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05831228
- Sponsor's protocol ID
- Pro00111000_1
- Status last verified
- May 2025
- First submitted
- 24 Mar 2023
- Last updated
- 3 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Pre-dive Ketone Food Products on Latency to Central Nervous System Oxygen Toxicity
- ClinicalTrials.gov ID
- NCT05831228
- Acronym / sponsor ID
- Pro00111000_1
- Conditions
- Oxygen Toxicity
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 20 participants (actual)
- Lead sponsor
- Duke UniversityUniversity, hospital or other
- Collaborators
- United States Navy
- Study start
- 1 Sep 2023 (actual)
- Primary completion
- 31 Mar 2025 (actual)
- Study completion
- 31 Mar 2025 (actual)
- First posted
- 26 Apr 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to understand how ketogenic food products affect oxygen toxicity in undersea divers. Oxygen toxicity affecting the central nervous system, mainly the brain, is a result of breathing higher than normal oxygen levels at elevated pressures as can be seen in SCUBA diving or inside a hyperbaric (pressure) chamber. This is a condition that may cause a wide variety of symptoms such as: vision disturbances, ear-ringing, nausea, twitching, irritability, dizziness, and potentially loss of consciousness or seizure. Because nutritional ketosis has been used to reduce or eliminate seizures in humans, it may be beneficial to reduce oxygen toxicity as well. The investigators hope this study will provide a help to develop practical and useful methods for improving the safety of undersea Navy divers, warfighters and submariners.
Detailed description
Central nervous system (CNS) oxygen toxicity continues to be a risk for military divers and constrains their operations. Manifestations of this condition range from nausea, twitching, and tinnitus to seizures and unresponsiveness, and the latter may lead to death by drowning. The NAVY has a need for better methods to prevent or delay the onset of CNS oxygen toxicity (CNSOT) and to safely expand the scope of diving operations. It is the broad objective of this study to generate information that will enhance warfighter safety and performance in relevant NAVY operations by reducing the risk of CNS oxygen toxicity.
It is known that nutritional ketosis through a diet with a high fat-to-carbohydrate ratio (ketogenic diet) can reduce the frequency and severity of epileptic seizures in humans, and a recent animal study has shown that dietary ketosis also delays the onset of CNSOT. In recent years, ketone ester food products ketone esters have been made commercially available which may elevate circulating ketone levels. The investigators aim to investigate whether ketosis from commercially available ketogenic food products prior to a dive will delay the onset of CNSOT.
The first aim of this study will be to determine the effect of ketone food product ingestion on serum ketone levels, and document any relevant side effects. Post-ingestion ketone levels will be trended for 3 different ketone food product regimens in 15 total subjects. Data will be used to select the optimal ketone food product strategy to investigate in the second aim.
This second aim will be to evaluate the primary hypothesis, that pre-dive ketone food products will prolong latency to CNSOT. To assess this, 20 subjects will be studied in a randomized, controlled, double-blind, crossover methodology. After consuming either the ketone food product or placebo, each subject will complete an immersed, head out hyperbaric oxygen exposure while exercising on an underwater cycle ergometer at 2.06 ATA (35 fsw) until oxygen toxicity symptoms develop or the maximum time limit of 120 minutes is reached. The experiment will be repeated on a different day by each subject after consuming the opposite (ketone food products or placebo). Primary outcome will be time to manifestation of CNSOT. Physiologic monitoring throughout the study will provide secondary endpoints such as cognitive performance, sympathetic nervous system stimulation via electrodermal activity, electroencephalography, cardiorespiratory measures and end-tidal CO2/O2/N2; all adding to our understanding of CNSOT physiology which may guide future mitigation and monitoring strategies.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Experimental: Ketogenic food products | Experimental | Dietary Supplement: Ketogenic food productsDietary Supplement: Ketogenic food products Participants will be given a ketogenic food product prior to the hyperbaric oxygen exposure. |
| Control: Placebo | Placebo comparator | Dietary Supplement: Control: PlaceboDietary Supplement comparator |
Who may qualify
- Ages
- 18 to 39 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Males \& females between 18 and 39 years old.
- Measured (Phase 2) VO2max ≥ 30 ml/kg/min (female) or 35 ml/kg/min (male).
- BMI ≤ 30.0 unless VO2max and baseline exercise profile is deemed appropriate for the study by the PI.
- (Phase 2 only) Able to exercise continuously on cycle ergometer for 2 hours.
- (Phase 2 only) Able to equalize middle ears and tolerate hyperbaric chamber exposure test.
Key exclusion criteria (19 listed)
- Prolonged QTc on initial ECG
- Currently pregnant or attempting to become pregnant.
- Have a medical history of:
- Regularly take any medications which may alter heart rate, blood pressure, neurotransmitter function, alter seizure threshold, mood or affect per PI discretion.
- Any other condition limiting ability to perform exercise testing or dive profile as determined by the investigators.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Ketogenic food productsParticipants will be given a ketogenic food product prior to the hyperbaric oxygen exposure. | Dietary supplement | Experimental: Ketogenic food products |
| Control: PlaceboParticipants will be given a dietary supplement comparator prior to the hyperbaric oxygen exposure. | Dietary supplement | Control: Placebo |
Primary outcome
Latency to central nervous system oxygen toxicity (CNSOT)
Time frame: 2 hours
Assessment of latency to CNSOT in a simulated working dive breathing 100% oxygen at 2.06 ATA, immersed in water (head out), in a hyperbaric chamber while performing exercise. Endpoint is time to development of signs or symptoms of CNSOT. Maximum duration 120 minutes.
9 secondary outcomes
Cognitive performance
Time frame: Day 1
Level of nutritional ketosis as detected by serume beta hydroxybutyrate levels
Time frame: Day 1
Number of participants with change in EEG
Time frame: Day 1
Change in qEEG alpha/delta power ratio (ratio of power in alpha frequency band to power in delta frequency band)
Time frame: Day 1
Change in end-tidal CO2
Time frame: Day 1
Change in venous CO2
Time frame: Day 1
Change in heart rate
Time frame: Day 1
Change in ventilatory rate
Time frame: Day 1
Number of participants who develop CNS oxygen toxicity
Time frame: Day 1
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Apr 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Bruce Derrick, MD principal investigator
Duke Health
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Ketogenic food products in people with Oxygen Toxicity, run by Duke University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 19 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 3 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Latency to central nervous system oxygen toxicity (CNSOT) (time frame: 2 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Apr 2026.