Effects of Chronic Acid-Base Changes on Ventilatory and Perceptual Responses

NCT00946933 | Completed

• 1 other identifier: DSS-16198
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

Approximately 30% of people aged 65 years and older experience breathlessness (perceived respiratory difficulty) during daily activity. The main causes of increased breathlessness in the healthy elderly are poorly understood and are the main focus of the proposed study. Some possible contributing factors include abnormalities in the control and/or mechanics of breathing. To evaluate these possible contributory factors, the investigators will compare ventilatory and perceptual responses to: 1) exercise, 2) increased levels of inspired carbon dioxide, and 3) reduced levels of inspired oxygen under strictly-controlled experimental conditions where the investigators increase or decrease breathing requirements by altering dietary salt intake in healthy 40-80 year old men and women. Exercise and rebreathing tests will be performed at baseline and at the end of each 3 day treatment period. Breathlessness intensity will be measured and compared at a standardized work rate, ventilation or end-tidal PCO2 during these tests.

Conditions

Healthy

Keywords

acid-base balance; ventilatory control; dyspnea; exercise; modified rebreathing procedure; Normal; older

Outcome Measures

Primary Outcomes (1)

• Breathlessness intensity (10-point Borg scale)

  Measured at the end of each 3 day treatment period

Secondary Outcomes (1)

• Exercise capacity (peak VO2)

  Measured at the end of each 3 day treatment period

Study Arms (2)

Placebo

PLACEBO COMPARATOR

0.025 g/kg/day of NaCl (sodium chloride)

Dietary Supplement: placebo

High salt diet

ACTIVE COMPARATOR

0.2 g/kg/day of NH4Cl (ammonium chloride)

Dietary Supplement: NH4Cl (ammonium chloride)

Interventions

NH4Cl (ammonium chloride) DIETARY_SUPPLEMENT

0.2 g/kg/day of NH4Cl (ammonium chloride)

High salt diet

placebo DIETARY_SUPPLEMENT

0.025 g/kg/day of NaCl (sodium chloride)

Placebo

Eligibility Criteria

• Age: 20 Years - 80 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• healthy, regularly active adults
• non-smoking
• BMI 18-30 kg/m2

You may not qualify if:

• history of lung and/or heart disease (including cardiac arrhythmias) or other comorbidity which could interfere with proper conduct of the intervention or tests
• hypotension or hypertension
• hypercholesterolemia
• sleep disordered breathing
• inability to perform cycle exercise or comply with other testing procedures

Sponsors & Collaborators

• Queen's University: lead

Study Sites (1)

Respiratory Investigation Unit at Kingston General Hospital

Kingston, Ontario, K7L 2V7, Canada

Location

MeSH Terms

Conditions

Dyspnea; Motor Activity

Interventions

Ammonium Chloride

Condition Hierarchy (Ancestors)

Respiration Disorders; Respiratory Tract Diseases; Signs and Symptoms, Respiratory; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Behavior

Intervention Hierarchy (Ancestors)

Chlorides; Hydrochloric Acid; Chlorine Compounds; Inorganic Chemicals; Ammonium Compounds; Nitrogen Compounds

Study Officials

• Denis E O'Donnell, MD, FRCPC

  Queen's University and Kingston General Hospital

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: July 23, 2009
• First Posted: July 27, 2009
• Study Start: November 1, 2009
• Primary Completion: September 1, 2010
• Study Completion: September 1, 2010
• Last Updated: December 17, 2012

Record last verified: 2012-12

Locations

CA (1)