Adjustment of positive end-expiratory pressure during presence of tonic diaphragm electrical activity in rabbits with acute respiratory distress syndrome

Abstract

Objective To study the positive end-expiratory pressure (PEEP) adjustment after recruitment maneuver during acute respiratory distress syndrome (ARDS) especially in the presence of tonic diaphragm electrical activity (Tonic EAdi) in order to obtain optimum PEEP and in turn to get successful oxygenation.Methods Rabbit model of ARDS was nade by intratracheal instillation of hydrochloric acid.After sufficient recruitment maneuvers,the rabbits were randomly (random number) divided into two groups,namely Tonic EAdi group ( n =5 ) and maximum oxygenation group ( n =5 ).In Tonic EAdi group,the regulation of PEEP was guided by Tonic EAdi.In maximum oxygenation group,PEEP was adjusted as per maximum oxygenation.The differences in magnitude of PEEP,pulmonary mechanics,gas exchange and hemodynamics were compared between two groups.The t-test was used to compare continuous variables between the two independent samples,and the difference was statistically significant when P ＜ 0.05.Results (1) PEEP:The PEEP was (10.7 + 1.4) cmH2O (1 cm H2O=0.098 kPa) in Tonic EAdi group and (10.0 ± 2.8) cm H2O in maximum oxygenation group (P ＞ 0.05). (2) Pulmonary mechanics:After PEEP adjustment,there was no significant difference in tidal volume ( Vr),peak pressure (Ppeak) and mean pressure (Pmean) between the two groups (P ＞ 0.05 ).(3) Gas exchange:After PEEP adjustment,there was no significant difference in oxygenation index (PaO2/FiO2) and partial pressure of arterial carbon dioxide ( PaCO2 ) between the two groups (P ＞ 0.05).Conclusions Tonic EAdi could be a good indicator for regulating PEEP in ARDS. Key words: Tonic electrical activity of diaphragm; Positive end-expiratory pressure; Acuterespiratory distress syndrome; Oxygenation index; Recruitment maneuvers