Using the Quasi-Static Pressure/Volume Curve to Identify Optimal PEEP & Recruitability

             

In previous post I mention evaluating the static P/V curve to set P-High when using Airway Pressure Release Ventilation (aka. APRV, BiLevel, BiVent) and to set optimal PEEP.

Another advantage of analyzing the static P/V curve is to identify if the patients lungs are recruitable. If they are not recruitable, then they will most likely not respond to higher levels of PEEP or placing them on APRV. 

The above video demonstrates the difference between recruitable & Non-recruitable lungs. 

RELATED POST
APRV: Setting P-High Based on the Static Pressure Volume Curve

Setting PEEP

The Constant Low Flow Method: Utilizing the PB840 part two

Identifying Optimal PEEP with the PB840 Ventilator: the Constant Low Flow Method

Setting PEEP

There is many ways to set Positive End Expiratory Pressure (PEEP). Setting PEEP too low may result in under or tidal recruitment of the lung and PEEP that is too high results in over-distention, both contribute to Ventilator Induced Lung Injury (VILI).  This post provides a synopsis of the various techniques as well as potential pros & cons.

The Minimal SSI Strategy

 

Stress Index (Si) Displayed on the SERVO-i Ventilator. 

In 2009 Brunner & Wysocki proposed that there is an optimal breathing pattern to minimize stress & strain during mechanical ventilation [1]. Stress and strain are primary causes of ventilator induced lung injury (VILI), so it would be imperative to provide a breathing pattern which decreases the chances of VILI. 

The Constant Low Flow Method: Utilizing the PB840 part two (video)

Additional Reading:

The Acute Effectiveness & Safety of the Constant-Flow, P/V Curve to Improve Hypoxemia in ALI.

Identifying Optimal PEEP with the PB 840 Ventilator: the "Constant Low Flow Method"

Evaluating the Pressure/Volume curve for the lower inflection point, provides the operator a idea of where to appropriately set the level of PEEP. The curve identifies where lung recruitment begins and at what pressure/volume creates over distention and/or injury.

In newer generation ventilators (Draeger's Evita XL or Hamilton's Galileo or G5 platforms) obtaining the static pressure/volume curve at a low flow state is simple via the machines automated tools.

Conversely, in other ventilators obtaining a static low flow P/V curve can be complicated if not impossible to perform.

The PB 840 does not have a automated tool for performing a "Low Flow" maneuver, however the practitioner can do the maneuver manually using the following steps (1):