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Time-Controlled Adaptive Ventilation (TCAV): a personalized strategy for lung protection
Journal article   Open access   Peer reviewed

Time-Controlled Adaptive Ventilation (TCAV): a personalized strategy for lung protection

Hassan Al-Khalisy, Gary F Nieman, Michaela Kollisch-Singule, Penny Andrews, Luigi Camporota, Joseph Shiber, Toni Manougian, Joshua Satalin, Sarah Blair, Auyon Ghosh, …
Respiratory research, Vol.25(1), 37
01/18/2024
DOI: 10.1186/s12931-023-02615-y
PMCID: PMC10797864
PMID: 38238778
url
https://doi.org/10.1186/s12931-023-02615-yView
Published (Version of record) Open Access

Abstract

Acute respiratory distress syndrome (ARDS) alters the dynamics of lung inflation during mechanical ventilation. Repetitive alveolar collapse and expansion (RACE) predisposes the lung to ventilator-induced lung injury (VILI). Two broad approaches are currently used to minimize VILI: (1) low tidal volume (LV ) with low-moderate positive end-expiratory pressure (PEEP); and (2) open lung approach (OLA). The LV approach attempts to protect already open lung tissue from overdistension, while simultaneously resting collapsed tissue by excluding it from the cycle of mechanical ventilation. By contrast, the OLA attempts to reinflate potentially recruitable lung, usually over a period of seconds to minutes using higher PEEP used to prevent progressive loss of end-expiratory lung volume (EELV) and RACE. However, even with these protective strategies, clinical studies have shown that ARDS-related mortality remains unacceptably high with a scarcity of effective interventions over the last two decades. One of the main limitations these varied interventions demonstrate to benefit is the observed clinical and pathologic heterogeneity in ARDS. We have developed an alternative ventilation strategy known as the Time Controlled Adaptive Ventilation (TCAV) method of applying the Airway Pressure Release Ventilation (APRV) mode, which takes advantage of the heterogeneous time- and pressure-dependent collapse and reopening of lung units. The TCAV method is a closed-loop system where the expiratory duration personalizes V and EELV. Personalization of TCAV is informed and tuned with changes in respiratory system compliance (C ) measured by the slope of the expiratory flow curve during passive exhalation. Two potentially beneficial features of TCAV are: (i) the expiratory duration is personalized to a given patient's lung physiology, which promotes alveolar stabilization by halting the progressive collapse of alveoli, thereby minimizing the time for the reopened lung to collapse again in the next expiration, and (ii) an extended inspiratory phase at a fixed inflation pressure after alveolar stabilization gradually reopens a small amount of tissue with each breath. Subsequently, densely collapsed regions are slowly ratcheted open over a period of hours, or even days. Thus, TCAV has the potential to minimize VILI, reducing ARDS-related morbidity and mortality.
 Acute respiratory distress syndrome TCAV Driving pressure Dynamic alveolar mechanics Alveolar opening and collapse time constants Tidal volume Ventilator-induced lung injury APRV Open lung approach Stress-multipliers Viscoelastic VILI ARMA ARDS Regional alveolar instability

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