Cs. Poon et al., NEGATIVE-IMPEDANCE VENTILATION AND PRESSURE SUPPORT VENTILATION - A COMPARATIVE-STUDY, Respiration physiology, 108(2), 1997, pp. 117-127
Negative impedance ventilation (NIV) is a novel mode of assisted mecha
nical ventilation (AMV) in which the pressure support is regulated to
continuously track inspiratory flow and/or volume. In this study, we h
ave evaluated the efficacies of NIV and inspiratory pressure support (
IFS) ventilation in a model of central airway obstruction in six rabbi
ts. For both AMV modes there was an inverse relationship between the i
ntrinsic work of breathing and alveolar pressure. Compared to IFS, NIV
was found to: (1) achieve the same degree of ventilatory unloading an
d similar level of pulmonary ventilation with considerably lower alveo
lar pressure; (2) better restore the normal tidal volume and respirato
ry frequency; (3) yield a shorter inspiratory duty cycle, thereby help
ing to rest the respiratory muscles and preclude intrinsic positive en
d-expiratory pressure. We conclude that NIV is more efficacious than I
FS in negating airway obstruction and offers a better trade-off betwee
n the risks of respiratory muscle fatigue and pressure induced complic
ations. (C) 1997 Elsevier Science B.V.