Ventilator manufacturers offer combinations of modes and breath types that characterize how and when a breath is delivered to the patient.
Ventilator modes most commonly found on the home care ventilator include:
Assist/control (A/C)
All breaths delivered by the ventilator will control either volume or pressure. The ventilator delivers the same measured breath every time, whether the breath is patient initiated or ventilator initiated, based on the rate setting.
Continuous positive airway pressure ventilation (CPAP)
All breathing is initiated and sustained by the patient. The ventilator delivers no machine (mandatory) breaths. The ventilator controls the delivered oxygen concentration and delivers as much flow and volume as necessary to meet the patient's inspiratory demands. The patient decides the tidal volume and number of spontaneous breaths.
This mode also allows the patient to breathe at a continuous, elevated airway pressure that can improve oxygenation (see PEEP/CPAP).
The ventilator can also apply positive pressure during spontaneous inspirations taken during CPAP mode to reduce the patient's work to breathe.
Synchronized intermittent mandatory ventilation (SIMV)
The ventilator synchronizes machine breath delivery with the patient's spontaneous breath efforts. This mode is a combination of set mandatory machine breaths synchronized with the patient's own spontaneous breaths.
Pressure control ventilation (PCV or PC)
This is a type of mandatory breath that can be used in either A/C or SIMV modes and targets a specific pressure during inspiration. The delivered flow rate varies according to the patient's demand and own lung characteristics, such as lung compliance and airway resistance. The delivered tidal volume also varies with changes in compliance and resistance. In PC mode, the clinician also sets a specific time for inspiration orinspiratory time.
Pressure support ventilation (PSV or PS)
This is a type of spontaneous breath that can be used in either CPAP or SIMV modes and targets a set inspiratory pressure, much like PC. But the PS inspiration ends as the lung gets full and the delivered flow decreases to a specific valve set by the clinician. The patient decides the respiratory rate and inspiratory time as well as the flow rate and tidal volume.
Positive end expiratory pressure (PEEP)
Mechanical positive pressure is applied at the end of exhalation to prevent the lungs from emptying completely and returning to a 'zero' reading. The benefit of positive pressure at the end of exhalation is increased lung volume for improved oxygenation.