Should PEEP Titration Be Based on Chest Mechanics in Patients With ARDS?

Abstract

Functional residual capacity (FRC) is essentially the alveolar volume and a determinant of both oxygenation and respiratory system compliance (CRS). ARDS decreases FRC, and sufficient PEEP restores FRC; thus, assessments of PEEP by its impact on oxygenation and CRS are intimately linked. PEEP also can ameliorate or aggravate ventilator-induced lung injury. Therefore, it can be argued that PEEP should be titrated primarily by its impact on CRS The pro position argues that the heterogeneous nature of lung injury and its unique presentation in individual patients results in an uncoupling between oxygenation and CRS Therefore, relying upon oxygenation alone may enhance lung injury and mortality risk, particularly in those with severe ARDS. The con argument is that the preponderance of preclinical and clinical evidence suggests that a relatively narrow range of PEEP is required to manage all but the most severe cases of ARDS. In addition, pathological alterations in chest wall compliance confuse the interpretation of chest mechanics. Moreover, ambiguities and technical limitations in advanced techniques, such as esophageal manometry and pressure-volume curves, add a layer of complexity that renders its broader application in all ARDS patients both impractical and unnecessary. Whether sophisticated monitoring of chest mechanics in severe ARDS might improve outcomes further is open to question and should be studied further. However, it is highly improbable that we will ever discover a PEEP strategy that optimizes all aspects of cardiorespiratory function and chest mechanics for individual patients suffering from ARDS.

Severity of Hypoxemia and Other Factors That Influence the Response to Aerosolized Prostacyclin in ARDS

“…In ARDS, mean FRC is reduced to between 1.8 and 0.6 L (or approximately 75 to 25% of normal). 11 Because FRC is essentially the alveolar volume and the primary determinant of oxygenation and compliance of the respiratory system (C RS ), 12 we hypothesized that the initial response to aerosolized prostaglandin I 2 in ARDS would be greater in those with less impaired oxygenation. We used both P aO 2 /F IO 2 and C RS as indirect correlates of FRC status.…”

Ventilator Graphics: Scalars, Loops, & Secondary Measures

“…47,67 In light of these issues, the best strategy for setting PEEP and V T remains controversial. In 2016, Kallet 75 published a pro/ con argument around the question of whether PEEP titration should be based on P-V plots. In the pro argument, he stated that 2 randomized controlled trials demonstrated significant reduction in mortality and duration of mechanical ventilation using open-lung ventilation based on P-V plots.…”

Predicting physiologic response to changes in positive end-expiratory pressure in mechanically ventilated children: a computable phenotype and machine learning approach

“…However, PEEP can ameliorate or exacerbate lung injury. (1) Although it is clinically important to optimize PEEP in this population, there is a paucity of literature to guide clinicians at the bedside. The physiologic rationale for increasing PEEP is often to reduce physiologic dead-space fraction, improve oxygenation and lung mechanics as well as improve shunt fraction and ventilation/perfusion mismatch.…”