{"id":1488,"date":"2026-03-22T11:18:22","date_gmt":"2026-03-22T11:18:22","guid":{"rendered":"https:\/\/perfusfind.com\/ic\/?p=1488"},"modified":"2026-03-22T11:18:22","modified_gmt":"2026-03-22T11:18:22","slug":"toward-optimal-mechanical-ventilation-of-the-injured-lung-the-role-of-expiratory-duration","status":"publish","type":"post","link":"https:\/\/perfusfind.com\/ic\/index.php\/2026\/03\/22\/toward-optimal-mechanical-ventilation-of-the-injured-lung-the-role-of-expiratory-duration\/","title":{"rendered":"Toward optimal mechanical ventilation of the injured lung: the role of expiratory duration"},"content":{"rendered":"

Abstract<\/h3>\n

This perspective challenges one of the most fundamental assumptions in ARDS ventilation: that only inspiratory forces<\/strong> (tidal volume, driving pressure, plateau pressure, mechanical power) shape lung injury. The authors argue that expiratory time<\/strong>\u2014specifically, the rate of lung emptying<\/em>\u2014is an overlooked determinant of stress and strain.<\/p>\n

In injured lungs with low compliance and heterogeneous time constants, rapid expiration may generate harmful regional pressure gradients, promoting \u201cimplosive\u201d injury as unstable units collapse too quickly. Conversely, excessively prolonged expiration risks de-recruitment and cyclic collapse.<\/p>\n

The authors propose that controlling expiratory duration<\/strong> may become a missing pillar of lung-protective ventilation, complementing tidal volume reduction, plateau pressure limitation, and optimized PEEP. They highlight the need for individualized management based on lung mechanics, time constants, and the balance between maintaining alveolar stability and preventing overdistension.<\/p>\n

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Key Insights<\/h2>\n
\n

1\ufe0f\u20e3 Lung injury does not occur only on inspiration \u2014 expiration matters too<\/h3>\n

Traditionally, VILI has been attributed to inspiratory overdistension and cyclic stretching. The authors emphasize that expiration can also impose injury through rapid pressure shifts and dynamic compression of unstable alveoli, especially in heterogenous ARDS lungs with mismatched time constants.<\/p>\n

2\ufe0f\u20e3 Injured lungs empty unevenly due to time-constant heterogeneity<\/h3>\n

Regions with short time constants empty quickly, while those with long time constants empty slowly. Rapid global expiration may cause \u201cimplosive\u201d collapse of vulnerable units, producing shear stresses comparable to the damaging forces seen during injurious inflation.<\/p>\n

3\ufe0f\u20e3 Classical lung-protection strategies focus only on inspiration<\/h3>\n

Low tidal volume, low plateau pressure, optimized PEEP, and driving pressure reduction form the modern protective framework. However, these fail to address how<\/em> the lung deflates, which may expose certain regions to abrupt collapse, deformation, and shear.<\/p>\n

4\ufe0f\u20e3 Expiratory flow limitation becomes clinically important<\/h3>\n

In injured lungs, expiratory flow may become too fast relative to regional mechanical properties. This creates transient but significant pressure gradients between units, a phenomenon that can amplify mechanical stress and propagate injury.<\/p>\n

5\ufe0f\u20e3 Too short an expiratory time may produce \u201cimplosive atelectrauma\u201d<\/h3>\n

The article describes how rapid deflation can cause immediate collapse of unstable alveoli, generating shear forces that resemble dynastic collapse injury. This mechanism may operate in parallel with classical atelectrauma during inspiration and warrants targeted mitigation.<\/p>\n

6\ufe0f\u20e3 Too long an expiratory time risks derecruitment<\/h3>\n

Prolonging expiratory duration to prevent rapid collapse may inadvertently promote cyclic derecruitment, particularly when PEEP is insufficient to maintain end-expiratory lung volume. Thus, expiratory timing\u2014like PEEP\u2014must be titrated individually.<\/p>\n

7\ufe0f\u20e3 The ideal expiratory duration is personalized, not fixed<\/h3>\n

The authors state that expiratory time must be tailored to the patient\u2019s:<\/p>\n