Effect Of The Different Ps Levels Of Non-invasive Positive Pressure Ventilation On Patient-ventilator Trigger Synchrony

Objective To investigate the effect of the different PS levels of non-invasive positive pressure ventilation on patient-ventilator trigger synchrony in healthy subjects and patients with acute exacerbation of chronic obstructive pulmonary disease in order to provide a theoretical basis of more rational clinical application in NPPV.Methods Eight healthy adults in Guangzhou Institute of Respiratory Disease received randomly the different PS levels(4cmH2O,8cmH2O,12cmH2O,16cmH2O and 20cmH2O respectively) of non-invasive positive pressure ventilation. Eight inpatients with acute exacerbation of COPD in Guangzhou Institute of Respiratory Disease received randomly low PS level , Optimal PS level and high low PS level of non-invasive positive pressure ventilation. The changes of inspiratory trigger time(TItri), trigger pressur-time product(PTPtri), respiratory center drive and ineffective triggering rate,etc were observed.Results1. Impact of PS levels on TItri.1) TItri(EMGdi), TItri(Pm), TItri(Peso) and TItri(Pdi) in healthy subjects increased with increasing PS levels(from 233.73±42.30 to 435.21±97.73ms, from 151.42±37.64 to 229.16±65.41ms, from 156.76±37.92 to 230.99±67.17ms and from 157.05±37.80 to 233.55±64.65ms respectively, P <0.05).2) At the same PS level, TItri(EMGdi) was longer than TItri(Pm), TItri(Peso) and TItri(Pdi) respectively in healthy subjects ( P <0.05) ,but the differences among TItri(Pm), TItri(Peso) and TItri(Pdi) were no statistics significance.3) TItri(EMGdi), TItri(Pm), TItri(Peso) and TItri(Pdi) in patients with chronic obstructive pulmonary disease. increased with increasing PS levels(from 241.38±37.88 to 375.73±68.62ms, from 174.44±38.77 to 225.69±85.03ms, from 164.30±45.93 to 223.73±80.58ms and from 161.80±45.99 to 222.80±78.21ms respectively, P <0.05).4) At the same PS level, TItri(EMGdi) was longer than TItri(Pm), TItri(Peso) and TItri(Pdi) respectively in patients with chronic obstructive pulmonary disease ( P <0.05) ,but the differences among TItri(Pm), TItri(Peso) and TItri(Pdi) were no statistics significance.2. Impact of PS levels on Tdif(Pm-EMGdi),Tdif(Peso-EMGdi) and Tdif(Pdi-EMGdi).1) Tdif(Pm-EMGdi), Tdif(Peso-EMGdi) and Tdif(Pdi-EMGdi) in healthy subjects increased with increasing PS levels(from 82.30±40.65 to 206.46±77.11ms, from 76.99±39.92 to 204.17±75.96ms and from 76.72±40.59 to 201.72±76.52ms respectively, P <0.05).2) At the same PS level, the differences among Tdif(Pm-EMGdi), Tdif(Peso-EMGdi) and Tdif(Pdi-EMGdi) were no statistics significance(P>0.05).3) Tdif(Pm-EMGdi), Tdif(Peso-EMGdi) and Tdif(Pdi-EMGdi) in patients with chronic obstructive pulmonary disease increased with increasing PS levels(from 66.94±32.83 to150.03±77.51ms, from 77.08±32.98 to 77.08±32.98ms and from 79.58±29.12 to 152.92±60.44ms respectively, P <0.05).4) At the same PS level, the differences among Tdif(Pm-EMGdi), Tdif(Peso-EMGdi) and Tdif(Pdi-EMGdi) were no statistics significance(P>0.05).3. Impact of the different PS levels on PTPtri.1) PTPtri(Pm),PTPtri(Peso) and PTPtri(Pdi) in healthy subjects did not change with increasing PS levels(from 79.14±23.24 to 79.89±26.82 cmH2O.ms, from 189.42±56.24 to 188.53±59.73 cmH2O.ms and from 197.51±62.47 to 191.37±61.85 cmH2O.ms respectively, P >0.05).2) PTPtri(Pm),PTPtri(Peso) and PTPtri(Pdi) in patients with chronic obstructive pulmonary disease did not change with increasing PS levels(from 51.56±20.68 to 58.23±17.62 cmH2O.ms, from 144.95±40.33 to 148.15±37.42 cmH2O.ms and from 168.07±46.92 to 166.43±46.66 cmH2O.ms respectively, P >0.05).4. Impact of the different PS levels on Respiratory drive.1) Progressive increases in PS level decreased total RR and RMSdi in healthy subjects(from 18.88±2.17 to 9.75±2.32b/min and from 47.63±6.38 to 15.67±5.15μνrespectively, P <0.05).2) Progressive increases in PS level decreased total RR and RMSdi in patients with chronic obstructive pulmonary disease (from 21.6±2.6 to 13.4±3.1b/min and from 45.29±6.45 to 16.67±5.22μνrespectively, P <0.05).5. Impact of the different PS levels on ineffective triggering. 1) Ineffective triggering rate in healthy subjects increased with increasing PS levels(from 0.25±0.71% to 9.13±5.54%,P <0.05).2) Ineffective triggering rate in patients with chronic obstructive pulmonary disease increased with increasing PS levels(from 0.38±1.06% to 11.38±6.92%, P <0.05).Conclusion1. Triggering delay time increased with increasing PS levels during NPPV. When NPPV was implemented, the inspiratory trigger time based on EMGdi was longer than that based on Peso,Pdi and Pm.2. When NPPV was implemented, the neural inspiratory onset based on EMGdi was earlier than that based on Peso,Pdi and Pm, and the differences were increased as the level of NPPV developed.3. The impact of the different PS levels on PTPtri.was not obvious during NPPV.4. Respiratory drive decreased with increasing PS levels during NPPV.5. Ineffective triggering increased with increasing PS levels during NPPV.