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

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00946933
Recruitment Status : Completed
First Posted : July 27, 2009
Last Update Posted : December 17, 2012
Information provided by (Responsible Party):
Dr. Denis O'Donnell, Queen's University

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.

Condition or disease Intervention/treatment Phase
Healthy Dietary Supplement: NH4Cl (ammonium chloride) Dietary Supplement: placebo Not Applicable

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: Effects of Chronic Acid-Base Changes on the Ventilatory and Perceptual Response to Hypercapnia, Hypoxia and Exercise in Healthy Older Adults
Study Start Date : November 2009
Actual Primary Completion Date : September 2010
Actual Study Completion Date : September 2010

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Placebo Comparator: Placebo
0.025 g/kg/day of NaCl (sodium chloride)
Dietary Supplement: placebo
0.025 g/kg/day of NaCl (sodium chloride)

Active Comparator: High salt diet
0.2 g/kg/day of NH4Cl (ammonium chloride)
Dietary Supplement: NH4Cl (ammonium chloride)
0.2 g/kg/day of NH4Cl (ammonium chloride)

Primary Outcome Measures :
  1. Breathlessness intensity (10-point Borg scale) [ Time Frame: Measured at the end of each 3 day treatment period ]

Secondary Outcome Measures :
  1. Exercise capacity (peak VO2) [ Time Frame: Measured at the end of each 3 day treatment period ]

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   20 Years to 80 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

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

Exclusion Criteria:

  • 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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00946933

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Canada, Ontario
Respiratory Investigation Unit at Kingston General Hospital
Kingston, Ontario, Canada, K7L 2V7
Sponsors and Collaborators
Queen's University
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Principal Investigator: Denis E O'Donnell, MD, FRCPC Queen's University and Kingston General Hospital
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Responsible Party: Dr. Denis O'Donnell, Principal Investigator, Queen's University Identifier: NCT00946933    
Other Study ID Numbers: DSS-16198
First Posted: July 27, 2009    Key Record Dates
Last Update Posted: December 17, 2012
Last Verified: December 2012
Keywords provided by Dr. Denis O'Donnell, Queen's University:
acid-base balance
ventilatory control
modified rebreathing procedure