What does pressure support (PS) only on a ventilator imply?

From the Guidelines

Pressure support (PS) only on a ventilator implies that the patient is breathing spontaneously while receiving ventilatory assistance that augments their inspiratory effort. In this mode, the ventilator delivers a preset positive pressure when the patient initiates a breath, making it easier for them to inhale 1. The patient controls both the respiratory rate and inspiratory time, while the ventilator simply provides a consistent pressure boost during inspiration.

Key Characteristics of Pressure Support

• The patient's respiratory effort triggers the ventilator both on and off, with the ventilator providing assistance only when the patient makes an effort to breathe 1.
• The level of pressure support can be adjusted to meet the individual needs of the patient, with the goal of reducing the work of breathing and improving respiratory comfort.
• PS is often used in conjunction with other modes of ventilation, such as PEEP, to maintain alveolar recruitment and prevent atelectasis.

Clinical Applications of Pressure Support

• PS is commonly employed during weaning from mechanical ventilation, as it allows patients to gradually resume more responsibility for their breathing while still receiving support 1.
• This mode is typically used for patients who have adequate respiratory drive and can trigger breaths independently but need some assistance to overcome resistance in the breathing circuit or to reduce work of breathing.
• The use of PS can help to improve patient outcomes by reducing the duration of mechanical ventilation and promoting more rapid recovery of respiratory function.

From the Research

Pressure Support on a Ventilator

• Pressure support (PS) is a mode of ventilation that provides assisted spontaneous breathing to patients with acute respiratory insufficiency (ARI) 2.
• PS is often used to convert patients from controlled mechanical ventilation to assisted spontaneous breathing as early as possible 2.
• The level of pressure support is set to achieve a tidal volume and respiratory rate that is comfortable for the patient 3.
• PS has been shown to be more comfortable than volume controlled-continuous mandatory ventilation (VC-CMV) in intubated mechanically ventilated patients 3.

Implications of Pressure Support

• PS can improve gas exchange by reducing ventilation-perfusion inequality in patients with acute lung injury (ALI) 4.
• However, controlled mechanical ventilation (CMV) may be more effective in improving gas exchange than PS in some cases 4.
• PS can also improve oxygenation in patients with moderate acute respiratory distress syndrome (ARDS) 5.
• The use of PS requires careful monitoring and adjustment of ventilator settings to ensure synchrony between the patient's breathing efforts and the ventilator's support 6.

Clinical Management

• Clinicians should be aware of the potential for dyssynchrony between the patient and ventilator during PS, which can lead to muscle overload and fatigue 6.
• Adjustments to the trigger variable, use of pressure versus fixed flow targeted breaths, and manipulations of the cycle variable can help enhance synchrony 6.
• Monitoring of airway pressure and flow graphics is essential to ensure proper use of PS and to minimize the risk of dyssynchrony 6.