What does inspiratory pressure look like on a mechanical ventilator (mech vent) monitor?

From the Guidelines

Inspiratory pressure on a mechanical ventilator monitor appears as an upward waveform, typically ranging from 10-30 cmH2O, with a rapid rise in pressure-controlled ventilation or a gradual rise to peak inspiratory pressure in volume-controlled ventilation. The waveform is crucial for monitoring patient-ventilator interaction and ensuring optimal ventilation settings. According to the most recent and highest quality study 1, a low tidal volume (4–6 ml/kg) and low plateau pressure (< 30 cmH2O) should be adopted for ARDS lung protective ventilation strategy. Key points to consider when interpreting inspiratory pressure on a mechanical ventilator monitor include:

• The pressure reading is measured in centimeters of water (cmH2O)
• Normal adult values typically range from 10-30 cmH2O, depending on the patient's condition and ventilator settings
• Elevated levels (>35 cmH2O) may indicate decreased lung compliance, airway obstruction, or patient-ventilator asynchrony, potentially leading to barotrauma
• Insufficient pressure may result in inadequate ventilation or atelectasis
• Clinicians should regularly assess the inspiratory pressure waveform alongside other parameters like tidal volume and flow to ensure optimal ventilator settings and patient comfort, as recommended by 1 and 1.

From the Research

Inspiratory Pressure on Mechanical Ventilator Monitor

Inspiratory pressure on a mechanical ventilator (mech vent) monitor can be understood by examining the different modes of ventilation and their effects on airway pressure.

• Pressure-controlled ventilation (PCV) limits the maximum airway pressure delivered to the lung, but may result in variable tidal and minute volume 2.
• Volume-controlled ventilation (VCV) offers the safety of a pre-set tidal volume and minute ventilation, but requires the clinician to appropriately set the inspiratory flow, flow waveform, and inspiratory time 2.
• During VCV, airway pressure increases in response to reduced compliance, increased resistance, or active exhalation and may increase the risk of ventilator-induced lung injury 2.

Factors Affecting Inspiratory Pressure

Several factors can affect inspiratory pressure, including:

• Tidal volume: Higher tidal volumes can result in higher inspiratory pressures 3.
• Inspiratory time: Longer inspiratory times can be used to increase mean airway pressure and improve oxygenation 3.
• Positive end-expiratory pressure (PEEP): Higher PEEP levels can improve oxygenation, but may also cause circulatory depression and lung injury from overdistention 4.
• Respiratory drive and effort: Monitoring respiratory drive and effort can help minimize lung and diaphragm injury, and airway occlusion pressure (P0.1) can be used as a noninvasive measure of respiratory drive 5, 6.

Monitoring Inspiratory Pressure

Inspiratory pressure can be monitored using various methods, including:

• Ventilator display: Many ventilators display inspiratory pressure and other respiratory parameters, allowing clinicians to monitor and adjust ventilation settings 2, 5.
• Airway occlusion pressure: P0.1 can be measured during an occlusion and used to estimate respiratory drive and detect potentially injurious levels of effort 5, 6.
• Esophageal pressure-time product: This measure can be used as a reference standard to evaluate the performance of P0.1 in detecting high and low effort 6.