Interaction between high frequency jet ventilation and cardiovascular function.

We have studied the interaction of high frequency jet ventilation with cardiovascular pressures and flows. Results in dogs show that the amplitude of all intrathoracic pressures and flows fluctuate with a frequency equal to the difference between the heart rate and ventilator rate. The magnitude of this amplitude variation may be sufficient to obliterate periodically the pulsations in pulmonary artery and right atrial pressures. It is also shown that these cardiovascular beats can occur when the ventilator rate is close to integral multiples of the heart rate. Direct measurement of pleural pressure and the observation that the beats are markedly reduced when the chest is open support the hypothesis that the primary mechanism responsible for these beats is the interaction of the respiratory fluctuations in pleural pressure with the cardiac-generated pressure pulsations.