An interventional study of Graded hypercapnia and Caffeine in Hypercapnia, sponsored by United States Army Research Institute of Environmental Medicine. Completed at 1 site in United States. Open to participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2024-10-15.
Sponsored by United States Army Research Institute of Environmental Medicine · Not applicable, Interventional, and Other
The aim of this randomized, double-blind, placebo-controlled crossover trial is to determine the effects of caffeine vs. placebo on psychomotor vigilance and carbon dioxide tolerance during graded hypercapnia.
Healthy and fit young adults (men and women) will participate in this study. Participants will perform two primary experimental trials on separate days, one after consuming 400 mg caffeine, and the other after consuming a non-caffeinated placebo. During each trial, participants will breathe increasing levels of inspired CO2 in a stepwise manner (0%, 2%, 4%, 6%, 8% CO2; all with 21% oxygen) during successive 12-minute stages. The endpoints of the graded hypercapnia protocol will be completion of the 8% CO2 stage, voluntary subject termination due to discomfort, or end-tidal CO2 greater than 70 mmHg. The investigators hypothesize that, compared to placebo, caffeine will lower end tidal and arterialized PCO2 and mitigate CO2-mediated decrements in psychomotor vigilance.
156 studies on the registry are indexed under Hypercapnia; 31 are open to participants now.
This study's enrollment of 29 is below the median of 36 across 120 interventional studies indexed under Hypercapnia.
Browse Hypercapnia studies →United States Army Research Institute of Environmental Medicine is the lead sponsor of 68 studies on the registry; 7 are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 2 (33%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Placebo (microcrystalline cellulose) capsule taken in a single dose 1 hour prior to graded hypercapnia
Other: Graded hypercapnia · Drug: Placebo
400 mg caffeine capsule taken in a single dose 1 hour prior to graded hypercapnia
Other: Graded hypercapnia · Drug: Caffeine
Volunteers breathe 0%, 2%, 4%, 6%, and 8% CO2 (with 21% O2, balance nitrogen) for 12 minutes each
400 mg caffeine capsule taken in a single dose 1 hour prior to graded hypercapnia
Placebo (microcrystalline cellulose) capsule taken in a single dose 1 hour prior to graded hypercapnia
End-tidal CO2
End-tidal CO2 (mmHg)
Time frame: 60 minutes
PVT Performance
Psychomotor vigilance (mean reaction time in s)
Time frame: 60 minutes
Carbon dioxide tolerance
Time spent in graded hypercapnia protocol (minutes)
Time frame: 60 minutes
Ventilation
Ventilation (L/min)
Time frame: 60 minutes
Respiratory Rate
Breaths per minute
Time frame: 60 minutes
Tidal volume
Tidal volume (L)
Time frame: 60 minutes
Oxygen Consumption
Oxygen consumption (L/min)
Time frame: 60 minutes
Carbon dioxide release
Carbon dioxide release (L/min)
Time frame: 60 minutes
Heart Rate
Heart Rate (Beats per minute)
Time frame: 60 minutes
Blood Pressure
Blood pressure (mmHg)
Time frame: 60 minutes
Total Mood Disturbance
Profile of Mood States (AU); higher number is worse mood
Time frame: 60 minutes
Arterialized capillary pH
pH (unitless)
Time frame: 60 minutes
Arterialized capillary PCO2
Partial pressure of carbon dioxide (mmHg)
Time frame: 60 minutes
Arterialized capillary bicarbonate
Bicarbonate (mmol/L))
Time frame: 60 minutes
Dyspnea
Borg 0-10 Scale (higher number is more dyspnea)
Time frame: 60 minutes
Discomfort
Borg 0-10 Scale (higher number is more discomfort)
Time frame: 60 minutes
Headache
100mm visual analog scale (higher number is worse headache)
Time frame: 60 minutes
Plasma caffeine
Plasma caffeine (ug/mL)
Time frame: 60 minutes
Plasma theobromine
Plasma theobromine (ug/mL)
Time frame: 60 minutes
Plasma theophylline
Plasma theophylline (ug/mL)
Time frame: 60 minutes
Plasma paraxanthine
Plasma paraxanthine (ug/mL)
Time frame: 60 minutes
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No
Ran from Nov 2023 to primary completion in Sep 2024, 10 months.
Of 50 non-industry interventional studies with no phase under Hypercapnia, half reached primary completion within 13 months of starting (the median), counting those still running; a quarter within 7 and three quarters within 32. This study's 10 months is below that.
Counting every sponsor, half of 54 studies reached it within 14 months; a quarter within 7 and three quarters within 32.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Oct 2024. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Caffeine
United States Army Research Institute of Environmental Medicine