How to Perform an Inspiratory Hold in PRVC Mode
To perform an inspiratory hold in PRVC mode, use the ventilator's dedicated inspiratory pause/hold button (typically labeled "Insp Hold" or "Inspiratory Pause") to temporarily halt inspiratory flow at end-inspiration, allowing measurement of plateau pressure (Pplat).
Technical Execution
The inspiratory hold maneuver in PRVC follows the same mechanical principles as in volume-controlled ventilation, since both modes deliver a set tidal volume. The key steps are:
- Locate the inspiratory hold control on your ventilator interface (button or touchscreen function)
- Apply the hold for 0.5-2 seconds at end-inspiration to allow pressure equilibration across the airways
- Read the plateau pressure from the ventilator display during the pause
- Release the hold to resume normal ventilation
Monitoring Parameters During the Hold
When performing inspiratory holds in PRVC, you should routinely monitor 1:
- Plateau pressure (Pplat) - should be maintained ≤30 cm H₂O in non-obese patients, ≤40 cm H₂O in obese patients
- Driving pressure (ΔP = Pplat - PEEP) - a critical determinant of lung stress
- Dynamic compliance - calculated as tidal volume/(Pplat - PEEP)
The 2019 international expert consensus strongly recommends (100% agreement) that Pplat and driving pressure should be monitored on all controlled mechanically ventilated patients 1.
Important Considerations for PRVC
PRVC differs from traditional volume control in that it uses variable pressure delivery to achieve target volume, but the inspiratory hold technique remains identical. During the hold:
- Peak inspiratory pressure (PIP) will drop to plateau pressure as flow ceases
- In PRVC, PIP is typically lower than in volume control ventilation 2, 3, but Pplat and driving pressure remain similar between modes 2
- The hold allows you to distinguish the resistive component (PIP - Pplat) from the elastic component (Pplat - PEEP) of airway pressure
Clinical Rationale
The inspiratory hold is essential for assessing true alveolar distending pressure, which cannot be determined from peak pressures alone. For the same tidal volume, there is no outcome advantage of using pressure-controlled versus volume-controlled ventilation in terms of stress and strain generated 4, making plateau pressure measurement equally important in PRVC.
Common Pitfalls to Avoid
- Insufficient hold duration: Holds <0.5 seconds may not allow complete pressure equilibration, especially in patients with high airway resistance
- Patient triggering during hold: Active patient effort during the maneuver invalidates the measurement; ensure adequate sedation or perform during passive ventilation
- Ignoring the driving pressure: Focusing only on Pplat without calculating ΔP misses a key predictor of ventilator-induced lung injury
- Excessive hold frequency: Repeated prolonged holds can cause patient discomfort and disrupt ventilation; perform only as clinically indicated for assessment