Impact of NaHCO3- on Exercise Hyperpnea

Study Overview
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Brief Summary
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An abnormally high V̇E/V̇CO2 response to exercise is a key pathophysiological feature of patients with chronic cardiopulmonary disease that is associated with adverse health outcomes. It follows that any intervention capable of decreasing the V̇E/V̇CO2 response to exercise has the potential to improve clinical and/or patient-reported outcomes. The investigators of this trial will compare the effects of orally administered sodium chloride (4 g, placebo) and sodium bicarbonate (0.3 g/kg of body mass) on ventilation, breathing pattern, dynamic operating lung volume, gas exhange, cardiovascular, metabolic and symptom parameters during symptom-limited, high-intensity, constant-work-rate cycle exercise testing in healthy adults aged 20-40 years.

Detailed Description
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The ventilatory response (V̇E) to exercise-induced increases in the rate of CO2 production (V̇CO2) depends on the regulated level of arterial PCO2 (PaCO2) and the dead space to tidal volume ratio (VD/VT). An abnormally high V̇E/V̇CO2 response to exercise, reflecting a high VD/VT and/or low PaCO2 equilibrium point, is a key pathophysiological feature of patients with chronic cardiopulmonary disease, including heart failure, pulmonary arterial hypertension, interstitial lung disease and chronic obstructive pulmonary disease. In these patient groups, exercise ventilatory inefficiency is associated with: disease severity and progression; exercise intolerance; exertional breathlessness; and increased risk of hospitalization, major cardiac events and mortality. It follows that any intervention capable of decreasing the V̇E/V̇CO2 response to exercise has the potential to improve clinical and/or patient-reported outcomes. Unfortunately, our ability to enhance exercise ventilatory efficiency is limited by the fact that, with the possible exception of lung volume reduction surgery in chronic obstructive pulmonary disease and pulmonary vasodilator therapy in pulmonary arterial hypertension and heart failure, ventilation-perfusion abnormalities reflecting a high VD/VT are often irreversible. A largely unexplored approach to decreasing the V̇E/V̇CO2 response to exercise is increasing the PaCO2 equilibrium point by inducing a metabolic alkalosis via administration of an alkalizing agent such as sodium bicarbonate (NaHCO3). Thus, the primary objective of this randomized, double blind, placebo controlled, crossover study was to test the hypothesis that increasing the PaCO2 equilibrium point via induced acute metabolic alkalosis by single-dose oral administration of NaHCO3 would decrease in the V̇E/V̇CO2 ratio at its lowest point (nadir) during high-intensity constant-load cycle exercise testing in healthy adults.

Official Title
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Effect of Induced Metabolic Alkalosis by Sodium Bicarbonate Administration on the Ventilatory Response to Exercise in Healthy Adults

Conditions
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Pulmonary Ventilation

Intervention / Treatment
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* Drug: Sodium Bicarbonate
* Drug: Sodium Chloride


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy Non-smoking Habitually active Non-obese (Body Mass Index <30 kg/m2) Normal lung function on spirometry Exclusion Criteria: Self-reported gastrointestinal, cardiovascular, vascular, respiratory, kidney, liver, musculoskeletal, endocrine, neuromuscular and/or metabolic disease/dysfunction Taking doctor prescribed medications other than oral contraceptives

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Sodium Bicarbonate<br>Ingestion of sodium bicarbonate (0.3 g/kg of body mass) | Drug: Sodium Bicarbonate<br> <br> |
| Placebo Comparator: Sodium Chloride<br>Ingestion of sodium chloride (4 g) | Drug: Sodium Chloride<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ventilatory equivalent to carbon dioxide (V̇E/V̇CO2) at its lowest point (nadir) during exercise | The V̇E/V̇CO2 nadir will be identified as the lowest 30-sec average data point during constant-load cycle exercise testing | Participants will be followed until all study visits are complete, an expected average of 3 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Partial pressure of carbon dioxide in the arterialized capillary blood (PacCO2) | PacCO2 (mmHg) will be measured at rest 90-min post-dose | Time Frame: Participants will be followed until all study visits are complete, an expected average of 3 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Exercise, Sodium Bicarbonate, Ventilatory equivalent for carbon dioxide