Bedside Adjustment of Proportional Assist Ventilation to Target a Predefined Range of Respiratory Effort*

Abstract

This first study assessing the clinical feasibility of titrating proportional assist ventilation with load-adjustable gain factors in an attempt to target a predefined range of effort showed that adjusting the level of assistance to maintain a predefined boundary of respiratory muscle pressure is feasible, simple, and often sufficient to ventilate patients until extubation.

Esophageal and transpulmonary pressure in the clinical setting: meaning, usefulness and perspectives

“…Values of Pmus between 5 and 10 cmH 2 O can be considered, as a crude estimate, to be the desirable respiratory effort during partial ventilatory support [39]. The work of breathing (WOB) of the respiratory muscles corresponds to the integral of the product of Pmus and the generated volume, represented graphically by the Campbell diagram [40] (Fig.…”

“…In patients who are assisted with proportional assist ventilation mode, the Pmus value can PTPes = Pmus · dt be estimated from the value of the Paw and the gain set by the clinician [39].…”

A Pilot Randomized Trial Comparing Weaning From Mechanical Ventilation on Pressure Support Versus Proportional Assist Ventilation*

“…2, Lausanne Switzerland) was inserted into the ventilator circuit to obtain a 60 ± 30 minute recording that was saved on a laptop computer for later analysis of Vt, ventilatory rate (RR vent ), minute ventilation (VE'), inspiratory time (Ti), total cycle time (Ttot), peak airway pressure (Peak Pao), delta pressure (ΔP), calculated as peak Pao minus extrinsic PEEP (13), and area under the inspiratory airway pressure time curve (PaoArea) (14) (ICU Lab 2.4; KleisTEK Advanced Electronic Systems, Bari, Italy). Asynchrony was detected by visual inspection of the recordings according to the method described by Thille et al (15).…”

“…However, these studies were limited in number of patients (12)(13)(14)(15) and duration (minutes to hours) and used an earlier version of PAV, which required physicians to manually measure compliance and resistance of the respiratory system during controlled MV. An automated, closed-loop system called "PAV with load-adjustable gain factors" (PAV+, Puritan Bennett 840 ventilator; Covidien, Boulder, CO) is now available, which automatically, frequently, and noninvasively measures compliance and resistance, making this mode more accessible for routine clinical use.…”

A New Purpose for Proportional Assist Ventilation?*

“…In this context, Carteaux et al (6), in this issue of Critical Care Medicine, take an initial step toward demonstrating a potential use of PAV in maintaining respiratory muscle work in a "normal or reasonable" target range as patients enter the weaning phase from mechanical ventilation. They theorize that such an approach is desirable because it should minimize dyspnea while avoiding both excessive or insufficient respiratory muscle work that could contribute to persistent fatigue (7) and ventilator-induced diaphragm dysfunction (VIDD) (8), respectively.…”