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Hemodynamic effects of resistive breathing
Journal of Applied Physiology (Bethesda, Md. : 1985)
|March 1, 1986
Summary
Breathing with external airway resistance during both inhalation and exhalation increases the heart's workload. This study simulated obstructive lung disease to assess hemodynamic effects, finding increased myocardial oxygen demand.
Area of Science:
- Physiology
- Cardiovascular System
- Respiratory System
Background:
- Obstructive lung diseases can cause significant intrathoracic pressure swings.
- Understanding the hemodynamic consequences of increased breathing effort is crucial.
Purpose of the Study:
- To investigate the acute hemodynamic effects of simulated airway obstruction.
- To quantify the impact of resistive breathing on myocardial oxygen consumption.
Main Methods:
- Eight healthy subjects breathed through external resistances simulating airway obstruction during rest and exercise.
- Mouth pressure, pleural pressure, heart rate, and systemic arterial pressure were monitored.
- Minute ventilation and end-tidal CO2 were measured to assess gas exchange.
Main Results:
- Inspiratory-expiratory resistive breathing increased heart rate and systolic blood pressure.
- Myocardial oxygen consumption, estimated via pressure-rate product, rose significantly (17-20%).
- Gas exchange was impaired, with decreased ventilation and increased end-tidal CO2.
Conclusions:
- Simulated airway obstruction significantly increases the metabolic load on the myocardium.
- Breathing against external resistance, particularly during both inspiration and expiration, elevates myocardial oxygen demand.