Background It has been demonstrated that aspirations could occur during respiratory failure, explained by a lack of co-ordination between swallowing and ventilation. To test this hypothesis, we examined the co-ordination of ventilation and swallowing in a completely unrestrained rat model during different level of hypercapnia, during hypoxia, and during tachypnea.
Methods A total of 50 male Wistar rats (250–350 g) were studied in a barometric plethysmograph to analyze swallowing and ventilation during swallowing, at different gas concentration [room air (G1), 10% of O2 and 0% of CO2 (G2), 21% of O2 and 5% of CO2 (G3), 21% of O2 and 10% of CO2 (G4), tachypnea (G5)].
Key Results During hypoxia, there was no difference between G2 and G1 regarding the swallowing parameters and ventilatory parameters. During hypercapnia, there was an increase in swallowing during inspiration in G4 (16 ± 20%P < 0.01) compared with G1. The analysis of ventilatory parameters during swallowing showed an increase in tidal volume (VT) and mean inspiratory time (VT/TI) (P < 0.001) with no change in respiratory cycle duration (TTOT), inspiratory time (TI), and expiratory time (TE) when compared with G1. During tachypnea (G5), the VT decreased (P < 0.05) without any change in VT/TI.
Conclusions & Inferences Our results on animal demonstrated that hypercapnia increased swallowing during inspiration, which was not the case for tachypnea or hypoxia, and could explain some aspirations during respiratory failure.