Abstract
BACKGROUND: We used a piglet model of respiratory failure to compare cardiopulmonary responses and pathologic effects on the airway mucosa and lung parenchyma of a combination of high frequency ventilation (HFV) and conventional breaths as provided by an electronic high frequency flow interrupter (HFFI) and a pneumatic oscillator (HFO). Unlike the HFFI, the HFO superimposed high frequency pulses on the conventional breaths. MATERIALS & METHODS: Twelve piglets (mean age 9 days, mean weight 2980 g), assigned at random to either ventilator, received lung lavage and 6 hours of ventilation (FIO2 1.0). Five additional piglets of similar characteristics received alternating HFFI and HFO. RESULTS: The combination of CMV and HFV was readily provided by both devices. Successful gas exchange was accomplished without cardiovascular compromise with either the well-known HFFI or the new pneumatic HFO. CONCLUSIONS: Absence of significant airway and lung injury suggests that the ventilatory strategies instituted resulted in alveolar recruitment and lung-volume maintenance. No beneficial effects of high frequency pulses superimposed on conventional breaths were observed in this study, but the unique capability of the pneumatic HFO to oscillate during lung inflations of different magnitudes and duration should be explored further.
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