Types of Ventilators

- 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

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, May 22, 2012 1:27 pm