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Fig. 6 | Annals of Intensive Care

Fig. 6

From: Prevention and treatment of acute lung injury with time-controlled adaptive ventilation: physiologically informed modification of airway pressure release ventilation

Fig. 6

Personalizing the release phase using the slope of the expiratory flow curve (SlopeFE). The release phase becomes briefer, directed by the SlopeFE with lung injury severity. a Normal lung release phase is 0.5 s, with moderate ARDS of 0.4 s and Severe ARDS of 0.3 s, all directed by changes in the SlopeFE. b The release phase duration is calculated by expiratory flow terminating (EFT) at 75% of the expiratory flow peak (EFP) (red arrow head). In this example, the EFP = − 50 l/min, so flow will be terminated (EFT) at − 37.5 l/min (− 50 l/min × 75% = − 37.5 l/min). Although the EFT is always at 37.5 l/min in our example, the release phase duration varies (0.3, 0.4, 0.5 s) due to changes in the SlopeFE (a, b). We did not directly measure the slope of the expiratory flow curve, but by terminating expiration at 75% of the EFT, changes in the slope change the expiratory duration (a, b). Thus, the release phase is both personalized and adaptive as the patient’s lungs become better or worse using the TCAV method. c Expiratory flow/time graphics on a ventilator monitor from a brain-dead organ donor meeting Berlin criteria for severe ARDS. The release phase was set using the equation: EFP × 75% = EFT. The SlopeFE when TCAV was initially applied was 58.8°, resulting in a release phase of 0.3 s. Twenty-four hours on TCAV and the SlopeFE increased to 76.3°, resulting in a release phase of 0.5 s. The spike in the expiratory flow curve is an artifact due to compression of gas in the ventilator circuit

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