Personalized ventilatory strategy based on lung recruitablity in COVID-19-associated acute respiratory distress syndrome: a prospective clinical study

Abstract

Background Heterogeneity is an inherent nature of ARDS. Recruitment-to-inflation ratio has been developed to identify the patients who has lung recruitablity. This technique might be useful to identify the patients that match specific interventions, such as higher positive end-expiratory pressure (PEEP) or prone position or both. We aimed to evaluate the physiological effects of PEEP and body position on lung mechanics and regional lung inflation in COVID-19-associated ARDS and to propose the optimal ventilatory strategy based on recruitment-to-inflation ratio. Methods Patients with COVID-19-associated ARDS were consecutively enrolled. Lung recruitablity (recruitment-to-inflation ratio) and regional lung inflation (electrical impedance tomography [EIT]) were measured with a combination of body position (supine or prone) and PEEP (low 5 cmH2O or high 15 cmH2O). The utility of recruitment-to-inflation ratio to predict responses to PEEP were examined with EIT. Results Forty-three patients were included. Recruitment-to-inflation ratio was 0.68 (IQR 0.52–0.84), separating high recruiter versus low recruiter. Oxygenation was the same between two groups. In high recruiter, a combination of high PEEP with prone position achieved the highest oxygenation and less dependent silent spaces in EIT (vs. low PEEP in both positions) without increasing non-dependent silent spaces in EIT. In low recruiter, low PEEP in prone position resulted in better oxygenation (vs. both PEEPs in supine position), less dependent silent spaces (vs. low PEEP in supine position) and less non-dependent silent spaces (vs. high PEEP in both positions). Recruitment-to-inflation ratio was positively correlated with the improvement in oxygenation and respiratory system compliance, the decrease in dependent silent spaces, and was inversely correlated with the increase in non-dependent silent spaces, when applying high PEEP. Conclusions Recruitment-to-inflation ratio may be useful to personalize PEEP in COVID-19-associated ARDS. Higher PEEP in prone position and lower PEEP in prone position decreased the amount of dependent silent spaces (suggesting lung collapse) without increasing the amount of non-dependent silent spaces (suggesting overinflation) in high recruiter and in low recruiter, respectively.

Respiratory Support Effects over Time on Regional Lung Ventilation Assessed by Electrical Impedance Tomography in Premature Infants

“…However, it should be acknowledged that our time intervals between data collection points were relatively short in comparison to those utilized in the aforementioned studies. One should also bear in mind that, unlike ARDS, neonatal RDS is a highly homogenous disease, and thus, the comparison should be interpreted cautiously, even if the treatment effect might be similar across populations [ 33 ].…”

Monitoring lung recruitment

“…The potential of R/I in discriminating high recruiters and low recruiters following PEEP application was confirmed by Taeneka et al [14 ▪▪ ]. R/I allowed the adoption of an individualized ventilatory strategy involving the application of high PEEP in high recruiters and low PEEP in low recruiters during pronation, thereby avoiding deterioration in lung collapse and overdistention [14 ▪▪ ]. However, a weak correlation was found between R/I and Crs, the amount of overdistention, and the amount of collapse [14 ▪▪ ].…”

“…An increase in R/I during pronation suggested the possibility of further recruitment with high PEEP, whereas a decrease in R/I during pronation indicated no additional improvement with high PEEP. The potential of R/I in discriminating high recruiters and low recruiters following PEEP application was confirmed by Taeneka et al [14 ▪▪ ]. R/I allowed the adoption of an individualized ventilatory strategy involving the application of high PEEP in high recruiters and low PEEP in low recruiters during pronation, thereby avoiding deterioration in lung collapse and overdistention [14 ▪▪ ].…”

“…R/I allowed the adoption of an individualized ventilatory strategy involving the application of high PEEP in high recruiters and low PEEP in low recruiters during pronation, thereby avoiding deterioration in lung collapse and overdistention [14 ▪▪ ]. However, a weak correlation was found between R/I and Crs, the amount of overdistention, and the amount of collapse [14 ▪▪ ]. Zhao et al [15 ▪▪ ] suggested that R/I might be an index of lung recruitment and overdistention simultaneously.…”

Setting positive end-expiratory pressure by using electrical impedance tomography

“…A study on patients with acute respiratory distress syndrome (ARDS) examined in prone and supine positions and ventilated at two PEEP values identified less dependent silent spaces without an increase of nondependent ones at higher PEEP only in recruiters and not in nonrecruiters [10 ▪ ]. In another study, silent spaces were applied to identify the PEEP level maintaining recruitment and minimizing the overdistension by performing a 4-step incremental/decremental PEEP trial in an experimental study [11].…”