- 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 depression