control of variables
Last reviewed 08/2021
The use of a ventilator allows manipulation of:
- minute volume = tidal volume x respiratory rate
- inspired oxygen concentration
These then can be varied for different patients - size - and different conditions:
- e.g. in ARDS where the patient has stiff lungs and difficulty oxygenating blood, then a large tidal volume - 1 litre - is required with a slow respiratory rate - 10-12/minute - and 100% inspired oxygen.
- e.g. in status asthmaticus with hyperinflated lungs and difficulty breathing, they require small tidal volume - 0.5 litres - and a slow respiratory rate - 12/minute. Also, the expiration time must be at least 50% of the respiratory cycle.
The process of weaning off the ventilator must be gradual.