The Advantages Of Electrical Impedance Tomography(EIT) During Individual PEEP Selection In ARDS Patients

Objective:Mechanical ventilation as an important support treatment for acute respiratory distress syndrome（ARDS）patients includes lung recruitment,the selection of positive end expiratory pressure（PEEP）,the determination of tidal volume,the setting of oxygen and carbon dioxide targets,prone position and other comprehensive treatment.A growing body of researches have shown that low tidal volume ventilation can reduce mortality in ARDS patients and reduce the days on the ventilator.But when it comes to PEEP settings,the results of different PEEP setting methods are various.With clinicians pay more attention to the change of local respiratory respiration in the lungs,there comes electrical impedance tomography（EIT）.There are less studies about this technology used in ARDS patients.As a single-center,prospective clinical controlled study,we will compare the PEEP/Fi O₂ tables with the EIT-PEEP titration method on mechanical ventilation time and intensive care unit（ICU）hospitalization time of ARDS patients.Methods:The population in this study were patients admitted to the general ICU in the Forth Hospital of Hebei Medical University from September 2020 to February 2021.Patients who still met the diagnostic criteria according to ARDS Berlin definition after more than 24 hours invasive mechanical were included.After baseline data collection,they were randomly divided into EIT group and PEEP/Fi O₂ Tables method group.PEEP settings were made according to EIT or PEEP/Fi O₂ Tables after grouping.Data collection were carried out on the first day and the third day.The end point was defined as weaning from mechanical ventilation or death.We recorded the length of ICU stay,mechanical ventilation duration,complications and prognosis at the end point.The primary outcomes were prognosis,mechanical ventilation time and ICU length of stay.Secondary outcomes were improvements in breathing and circulation.Results:A total of 49 patients who met the inclusion criteria were included in the study,and 25 patients were excluded.The remaining 24patients were randomly divided into EIT group（n=14）and PEEP/Fi O₂ Tables method group（n=10）.Of all patients,70.8%was pulmonary ARDS patients,and 75%was surgical patients.There was no statistic difference in baseline characteristics between the two groups.On the first day,the driving pressure of the EIT group were lower than the PEEP/Fi O₂ table group（12.8±3.3cm H₂O,15.8±2.7cm H₂O,P=0.03）and compliance were better（32.5±6.6m L/cm H₂O,24.3±3.9m L/cm H₂O,P<0.01）.On the third day,the EIT group had a higher dead space rate（14.8±7.0%,9.2±3.0%,P=0.02）and a lower drive pressure which was 13.5（12.8-14.3）cm H₂O and15.5（13.8-18.0）cm H₂O,P=0.01.And the lung ultrasound score of the EIT group was lower（13.9±2.3,18.7±3.8,P<0.01）.In terms of complications,the table group had more kidney injuries than the EIT group（21.4%,70.0%,P=0.03）.The mortality rates for the EIT group and the PEEP/Fi O₂ table group were respectively 28.6%,30.0%;mechanical ventilation time of two groups were 6.0（5.0-15.8）days and 7.5（5.8-10.5）days;the ICU length of stay of two groups were 9.5（8.0-23.3）days and 11.0（10.0-14.5）days,but there were no statistical differences.Conclusions:Individualized PEEP setting in patients with acute respiratory distress symptoms is still an active area of study.This study verified the value of EIT in clinical applications and proofed that the EIT-PEEP titration can reduce transpulmonary pressure and enhance lung compliance.