Influence of Caffeine on Psychomotor Vigilance and Carbon Dioxide Tolerance During Graded Hypercapnia

NCT ID: NCT06636825

Last Updated: 2024-10-15

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 29 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2023-11-09
• Study Completion Date: 2024-09-17

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.

Conditions

Hypercapnia

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: OTHER
• Blinding Strategy: DOUBLE

Study Groups

Placebo

Placebo (microcrystalline cellulose) capsule taken in a single dose 1 hour prior to graded hypercapnia

Group Type: PLACEBO_COMPARATOR

Graded hypercapnia

Intervention Type: OTHER

Volunteers breathe 0%, 2%, 4%, 6%, and 8% CO2 (with 21% O2, balance nitrogen) for 12 minutes each

Placebo

Intervention Type: DRUG

Placebo (microcrystalline cellulose) capsule taken in a single dose 1 hour prior to graded hypercapnia

Experimental

400 mg caffeine capsule taken in a single dose 1 hour prior to graded hypercapnia

Group Type: EXPERIMENTAL

Graded hypercapnia

Intervention Type: OTHER

Volunteers breathe 0%, 2%, 4%, 6%, and 8% CO2 (with 21% O2, balance nitrogen) for 12 minutes each

Caffeine

Intervention Type: DRUG

400 mg caffeine capsule taken in a single dose 1 hour prior to graded hypercapnia

Interventions

Graded hypercapnia

Volunteers breathe 0%, 2%, 4%, 6%, and 8% CO2 (with 21% O2, balance nitrogen) for 12 minutes each

Intervention Type: OTHER

Caffeine

400 mg caffeine capsule taken in a single dose 1 hour prior to graded hypercapnia

Intervention Type: DRUG

Placebo

Placebo (microcrystalline cellulose) capsule taken in a single dose 1 hour prior to graded hypercapnia

Intervention Type: DRUG

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)

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 45 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

United States Army Research Institute of Environmental Medicine

FED

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Locations

US Army Research Institute of Environmental Medicine

Natick, Massachusetts, United States

Countries

United States

Provided Documents

Document Type: Informed Consent Form

View Document

Other Identifiers

23-05

Identifier Type: -

Identifier Source: org_study_id