From the Guidelines
Pressure support (PS) is a ventilator mode that provides a preset amount of positive pressure during inspiration, typically started at 5-10 cmH2O and titrated based on patient comfort, respiratory rate, and tidal volume, to reduce the work of breathing in patients who are breathing spontaneously but need assistance. This mode is particularly useful during weaning from mechanical ventilation, as it can be gradually decreased from higher levels to minimal support before extubation, with studies such as 1 showing that conducting spontaneous breathing trials (SBT) with pressure augmentation can lead to higher rates of successful SBTs and extubation success. Some key points to consider when using pressure support include:
- The amount of pressure support provided can vary, but common levels include 5,7, or 8 cm H2O, as seen in the study 1
- The goal of pressure support is to maintain tidal volumes of 6-8 mL/kg of ideal body weight, while reducing the work of breathing and preserving respiratory muscle function
- Pressure support works by maintaining positive pressure throughout inspiration until the patient's inspiratory flow decreases to a certain threshold, at which point the ventilator cycles to expiration, as described in the context of mechanical ventilation 1
- The use of pressure support can be associated with a trend toward lower ICU mortality, although the evidence for this is of low certainty, as noted in the study 1.
From the Research
Definition of Pressure Support (PS)
- Pressure support (PS) is a mode of ventilatory assistance that augments the patient's spontaneous inspiratory efforts with a clinician-selected level of positive airway pressure 2.
- It is widely used during the weaning phase in patients with acute respiratory distress syndrome to prevent ventilator-induced lung injury while limiting the patient's work of breathing 3.
Mechanism of Pressure Support
- Pressure support ventilation (PSV) provides a monotonous pattern of support for respiration, which is normally a dynamic process 4.
- The pressure-support level is adjusted to prevent diaphragmatic fatigue and to promote a nonfatiguing respiratory muscle activity 5.
- PSV can assist spontaneous breathing and avoid diaphragmatic fatigue by allowing adjustment of the work of each breath to provide an optimal muscle load 5.
Comparison with Other Ventilation Modes
- Neurally adjusted ventilatory assist (NAVA) is an assist mode that applies a positive pressure proportional to the integral of the electrical activity of the diaphragm, and has been compared to PSV in several studies 3, 6.
- NAVA has been shown to limit the risk of overassistance, prevent patient-ventilator asynchrony, and improve overall patient-ventilator interactions compared to PSV 3.
- A randomized crossover trial found that NAVA and PSV were feasible as a protective ventilation strategy in selected ARDS patients, with similar tidal volumes and respiratory rates 6.