Clinical trial NCT06636825: Influence of Caffeine on Psychomotor Vigilance and Carbon Dioxide Tolerance During Graded Hypercapnia
Official title: Influence of Caffeine on Psychomotor Vigilance and Carbon Dioxide Tolerance During Graded Hypercapnia
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Hypercapnia
Keywords: Caffeine
Carbon dioxide
Cognitive Function
Lead sponsor: United States Army Research Institute of Environmental Medicine
Sponsor class: FED
First posted: 2024-10-15
Enrollment: 29
Sex: ALL
Minimum age (years): 18
Maximum age (years): 45
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: Randomized, double-blind, placebo-controlled crossover trial
Primary purpose: OTHER

Brief summary: 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.

Detailed description: 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.

Eligibility criteria: Inclusion Criteria:

* Male or female, age 18-45
* Body mass index 18.5-30.0 kg m-2
* Body mass 50-100 kg
* In good health as determined by the Office of Medical Support \& Oversight (OMSO) General Medical Clearance
* Perform exercise at least 2 times per week
* Willing to abstain from exercise and alcoholic beverages for 24 hours before each study visit.
* Willing to abstain from caffeine for 12 hours prior to all study visits
* Willing to abstain from caffeine for 12 hours after visits 3 and 4
* Willing to remain fasted (no food or fluid other than water) from lights out until after arrival at the laboratory the following morning on each study day (\~10 hours)
* Have supervisor approval if permanent party military or a federal employee at U.S. Army Natick Soldier System Center

Exclusion Criteria:

* Females who are pregnant or planning to become pregnant during the study
* Females who are surgically sterile
* History of severe adverse reaction to caffeine (e.g., headache, dizziness, diarrhea, insomnia)
* Taking dietary supplements, prescriptions, or over the counter medication, other than a contraceptive (unless approved by OMSO \& PI)
* Abnormal blood count (For example: hemoglobin (Hb) outside of the typical normal values reported by LabCorp in accordance with OMSO (Normal \[Hb\] Males = 12.6-17.7 g/dL; Females = 11.1-15.9 g/dL) or hematocrit (Hct) outside of the normal ranges (Normal Hct Males = 37.5-51.0%; Females = 34.0-46.6%) levels, presence of abnormal blood chemicals (hemoglobin S or sickle cell traits)
* Any history of pulmonary or cardiovascular disease
* Current diagnosis of asthma (childhood asthma with no recurrence in the last 5 years ok)
* Smokers or nicotine users (unless have quit \>1 month prior)
* Current or recent respiratory tract or sinus infections (\< 1 month prior)
* Current diagnosis of migraine or recurrent headaches (previous diagnosis with no recurrence in the last 5 years ok)
* Any history of seizures
* Any history of panic disorder
* Blood donation in the previous 8 weeks
* Positive Covid-19 test within the last month (based on self-report)

Primary outcomes:
measure: End-tidal CO2
timeFrame: 60 minutes
measure: PVT Performance
timeFrame: 60 minutes
measure: Carbon dioxide tolerance
timeFrame: 60 minutes
Secondary outcomes:
measure: Ventilation
timeFrame: 60 minutes
measure: Respiratory Rate
timeFrame: 60 minutes
measure: Tidal volume
timeFrame: 60 minutes
measure: Oxygen Consumption
timeFrame: 60 minutes
measure: Carbon dioxide release
timeFrame: 60 minutes
measure: Heart Rate
timeFrame: 60 minutes
measure: Blood Pressure
timeFrame: 60 minutes
measure: Total Mood Disturbance
timeFrame: 60 minutes
measure: Arterialized capillary pH
timeFrame: 60 minutes
measure: Arterialized capillary PCO2
timeFrame: 60 minutes
measure: Arterialized capillary bicarbonate
timeFrame: 60 minutes
measure: Dyspnea
timeFrame: 60 minutes
measure: Discomfort
timeFrame: 60 minutes
measure: Headache
timeFrame: 60 minutes
measure: Plasma caffeine
timeFrame: 60 minutes
measure: Plasma theobromine
timeFrame: 60 minutes
measure: Plasma theophylline
timeFrame: 60 minutes
measure: Plasma paraxanthine
timeFrame: 60 minutes
Other outcomes:
Locations:
city: Natick
country: United States
facility: US Army Research Institute of Environmental Medicine
state: Massachusetts
Study officials:
References: