THE EFFECT OF HIGH-FREQUENCY VENTILATION ON PATTERN OF BREATHING OF ANAESTHETIZED RABBITS

¹ The Department of Physiology, University Medical School, Edinburgh EH8 9AG

The lungs of anaesthetized rabbits were ventilated with a frequency of 30 Hz and a displacement of 5 ml. High-frequency ventilation (HFV) was superimposed on static inflation or deflation pressures of 2·5 and 5 cmH₂O and was maintained for 10 s. Changes in pattern of breathing in response to this procedure were recorded before and during block of pulmonary stretch receptors by SO₂. With lung stretch receptors intact apnoea or extended duration of expiration demonstrated the predominant role of pulmonary stretch receptors in the response to HFV. Block of stretch receptors exposed effects of other pulmonary afferents, presumably rapidly adapting receptors, during HFV, and demonstrated the influence of their sustained stimulation on pattern of breathing as augmented breaths and the reduction of duration of expiration. High-frequency ventilation may represent a useful experimental method of stimulating rapidly adapting receptors.