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Respiratory sinus arrhythmia in man: relation to right ventricular output
Scandinavian Journal of Clinical and Laboratory Investigation
|September 1, 1976
Summary
Negative and positive pressure ventilation significantly impact heart rate and right heart blood flow. These respiratory maneuvers alter stroke volume and pulmonary arterial flow, suggesting a link to heart rate regulation.
Area of Science:
- Cardiovascular Physiology
- Respiratory Physiology
Background:
- Respiratory maneuvers influence cardiovascular function.
- Understanding the effects of intrathoracic pressure changes on cardiac output is crucial.
Purpose of the Study:
- To investigate the beat-by-beat respiratory effects on heart rate (HR), right ventricular stroke volume (SVRV), and pulmonary arterial flow (PAF).
- To compare the effects of negative inspiratory pressure (NIP) and intermittent positive pressure ventilation (IPPV) on these cardiovascular parameters.
Main Methods:
- Studied 7 healthy subjects using beat-by-beat measurements.
- Applied controlled tidal volumes (VT) with varying intrathoracic pressures: negative inspiratory pressure (NIP) and intermittent positive pressure ventilation (IPPV).
- Utilized control experiments with standard breathing rates and tidal volumes.
Main Results:
- Control conditions showed an inspiratory increase in HR and SVRV (respiratory sinus arrhythmia).
- NIP augmented the inspiratory increase in SVRV and respiratory oscillations of PAF.
- IPPV decreased SVRV and HR during inspiration.
Conclusions:
- Both NIP and IPPV significantly affect right ventricular stroke volume and right heart blood flow.
- Observed similarities in HR and SVRV responses suggest a potential role for heart-rate-regulating reflexes.