Impact of NaHCO3- on Exercise Hyperpnea

Early Phase 1

Completed

• Conditions: Pulmonary Ventilation
• Interventions: Drug: Sodium Bicarbonate; Drug: Sodium Chloride

• Registration Number: NCT03057535
• Lead Sponsor: McGill University

Brief Summary

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

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.

Study Timeline

• Study Start: 2015-05
• Primary Completion: 2016-04
• Study Completion: 2016-09
• Status Verified: 2017-02
• Study First Submitted: 2017-02-10
• Study First Submitted QC: 2017-02-15
• Last Update Submitted: 2017-02-15
• Study First Posted: 2017-02-20
• Last Update Posted: 2017-02-20

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 20

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Sodium Bicarbonate	Sodium Bicarbonate	Ingestion of sodium bicarbonate (0.3 g/kg of body mass)
Sodium Chloride	Sodium Chloride	Ingestion of sodium chloride (4 g)

Primary Outcome Measures

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

Secondary Outcome Measures

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

Trial Locations

Locations (1)

McGill University, Department of Kinesiology & Physical Education, Clinical Exercise & Respiratory Physiology Laboratory; 🇨🇦 Montreal, Quebec, Canada