- Time cycled ventilator: - Time delivery of gas flow;
tidal volume = flow
rate x insp. time - Delivers relatively constant Tidal Volume; - Allows precise control of gas delivery; - Types:
IMV-Bird, Foregger 210, Emerson;
- Volume Cycled Ventilator: - Inspiratory gas flow terminated after preselected volume delivery - Pressure in circuit determined by
tidal volume and
Compliance; - Delivered Tidal volume changes with changes in
Compliance; - Types: Bennett, Ohio 560, Bourns Bear 1, Monaghan, Siemons Servo;
- Pressure cycled ventilators: - Gas flow continues until preset pressure develops; -
tidal volume = Flow
rate x Time until pressure is reached; - Variable volume if circuit pressure varies (change in
Compliance); - Types: Bird Mark, Bennett PR;
- High Frequency Ventilators: - 5 types: - High frequency positive pressure ventilation - Jet ventilation - Flow interruption - Oscillation - Percussive ventilation
- Advantages: - Lower Mean airway pressure - Lung volume is increased
- Indications: - Closed Head injury: lower intracranial pressure - Larger pulmonary air leaks / Fail chest w/ contussions - Hemodynamic instability: less
CO depression; - Refractory respiratory depressioin;
