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Altered cardiovascular reflex responses during positive pressure breathing
Federation Proceedings
|June 1, 1981
Summary
Positive end-expiratory pressure (PEEP) affects cardiovascular responses through complex reflex interactions. Cardiopulmonary mechanoreceptors and baroreceptors exert conflicting influences on heart rate and blood pressure during PEEP-induced hyperinflation.
Area of Science:
- Cardiovascular Physiology
- Respiratory Physiology
- Neuroscience
Background:
- Positive end-expiratory pressure (PEEP) can alter cardiovascular function through mechanical effects and reflex mechanisms.
- The interplay between cardiopulmonary mechanoreceptors and systemic baroreflexes during PEEP-induced hyperinflation is not fully understood.
Purpose of the Study:
- To investigate the modulatory interactions between cardiopulmonary mechanoreceptors and systemic baroreflexes during PEEP-induced hyperinflation.
- To differentiate the roles of chemo-, mechano-, and baroreflexes in cardiovascular responses to PEEP.
Main Methods:
- Anesthetized rabbits with a closed chest were subjected to incremental PEEP (0-7.5 cm H2O).
- Cardiovascular parameters were monitored before and after progressive elimination of reflexes (carotid intrasinus pressure control, aortic denervation, vagotomy).
Main Results:
- Heart rate responses to PEEP changed from an initial increase to a decrease and then abolition after baroreflex and vagal elimination, respectively.
- The fall in mean arterial pressure (MAP) during PEEP was exacerbated by baroreflex elimination and attenuated by vagotomy.
- Vagal receptors were suggested to influence both venous and arterial vascular pressure.
Conclusions:
- Cardiopulmonary mechanoreceptors and arterial baroreceptors exert opposing reflex influences on cardiovascular responses during PEEP-induced hyperinflation.
- Vagal afferents play a significant role in modulating systemic arterial pressure and heart rate during PEEP.