Association of driving pressure with the recruitment/inflation ratio in personalized positive end-expiratory pressure management: feasibility for bedside use?: a single-center prospective cohort study

Background Positive end-expiratory pressure (PEEP) titration is crucial for preserving lung mechanics and physiology in mechanically ventilated patients. End-expiratory lung volume (EELV) and compliance can be used for this purpose. Based on these parameters, the Recruitment/Inflation ratio (R/I) has been used to estimate lung recruitability. We aimed to investigate the relationship between driving pressure and the Recruitment/Inflation ratio at two consecutive PEEP levels for appropriate PEEP selection in patients receiving mechanical ventilation support. Methods End-expiratory lung volume (EELV) was measured during a decremental PEEP trial (PEEP levels of 20,15,10 and 5 cmH₂O). The PEEP level associated with the lowest driving pressure among the four tested PEEP levels was selected. Patients were then ventilated at this selected PEEP level for 24 hours. Subsequently, using the collected data, the R/I rate was calculated between consecutive PEEP levels. If the R/I rate was equal or above a pre-defined cut-off value, the higher of the two consecutive PEEP levels was considered potentially recruiting. If the R/I rate was below the cut-off value, the lower PEEP level was considered appropriate. Finally, the relationship between the PEEP level associated with the lower driving pressure (between two consecutive PEEP steps) and the PEEP level deemed appropriate based on the R/I rate cut-off was examined. Results The highest value of the arterial partial pressure of oxygen to fraction of inspired oxygen ratio (PaO₂/FiO₂) was measured at the 20 cmH₂O PEEP level. EELV was found to be higher in patients classified as high recruiters (Group C and Group A) (P = 0.033). The PaO₂/FiO₂ ratio was also higher in the high-recruiter Group C (P = 0.008). In our study, the relationship between driving pressure and the R/I rate for appropriate PEEP selection has been determined. The agreement between PEEP selection guided by driving pressure and PEEP selection guided by the R/I rate did not reach statistical significance in our study. Conslusion: Sufficient and robust evidence to support the standalone use of the R/I rate in clinical practice has not yet been established. Further studies are needed for this purpose.