ABSTRACT
Objective To study the changes of trans-diaphragmatic pressure (Ptra) and its correlation with esophageal pressure (Peso) through ARDS piglet model.Methods Five piglets were enrolled in the study.Peso,gastric pressure (Pgas) and intra-thoracic pressure (Pint) was monitored through balloon inserted.The data before ARDS serve as control.ARDS was produced in the piglets through saline lavage.The pressure were observed and the Ptra were calculated.The pressure changes and correlation between Ptra and Peso were analyzed as well.Linear regression with the coefficient of determination and t-test were used as appropriate.Significance was assumed for P ＜ 0.05.Results Peso,Pgas and Pint before ARDS were 7.3 ± 1.9,25.5 ± 2.4,- 1.23 ± 0.21 cmH2O,Ptra was 18.2 ± 1.6 cmH2O.While after ARDS,the data were 4.7 ± 1.4,31.1 ± 3.1 and - 1.79 ± 0.28 cmH2O,and Ptra was 26.4 ± 2.1 cmH2 O,and all these changes were obviously ( P ＜ 0.05 ).The correlation between Pint and Peso,Pint and Ptra (A) and Ptra ( B ) were 0.93 ± 0.025,0.88 ± 0.023 and 0.87 ± 0.37 before ARDS.After ARDS,the correlation changed to be 0.82 ±0.21,0.81 ±0.20 and 0.78 ±0.31.Although a bit decreased,the correlation was still positive (P ＜ 0.01 ).Conclusions There existed good correlations between Peso and Ptra as well as between Pint and Peso before or after ARDS.Ptra was increased obviously after ARDS,which could lead to respiratory muscle fatigue.
ABSTRACT
After electrical stimulation of the phrenic nerve,the function of the diaphragm was assessed by measurement of the transdiaphragmatic pressure (PDi),establishment of the Pdi-sti-mulating frequency (F) curve,and analysis of the power spectrum on the diaphragmatic elec-tromyogram (EMGdi) at spontaneous breathing.Hypercapnia of the dogs was induced by forcing the animals to inhale a mixture of CO2 and air.The findings were as follows:(1) After acute hypercapnia,PDi rapidly and progressively decreased.The power spectrum of EMGdi was also reduced.The PDi-F curve was shifted to right.These findings suggest that the function of the diaphragm was severely damaged.(2) The decrease of pH value was the important cause of diaphragmatic fatigue.(3) The diaphragm in a static condition could reduce the damage of hypercapnia.(4) Cedi-lanid exerted certain effects on the prevention of diaphragmatic fatigue created by acute hypercapnia.
ABSTRACT
Experiments were performed on spontaneously breathing rabbits anesthetized with urethan. The diaphragmatic fatigue (DiF) was reproduced by the phrenic nerve stimulation (30 Hz, 10 V,0. 2 ms). The transdiaphragmatic pressure (Pdi) and diaphragm evoked potential (DEP) were measured before injury and after injury 30, 60, 90, and 120 min. Pdimax and the amplitude of DEP obviously decreased and the latency of DEP obviously delayed after injury 30min. The amplitude of Pdi and DEP were quickly promoted by introvenous injection of neostig-mine after DiF. The latency of DEP was partially recovered by introvenous injection of neostig-mine. It is concluded that neostigmine can improve the generation of the fatigued diaphragm. and promote its recovery.
ABSTRACT
AIM: To investigate the application of phrenic nerve conduction time(PNCT) in the recovery of general anaesthesia. METHODS: Pdi (t) and PNCT were measured by cervical magnetic stimulation of phrenic nerves in 8 patients before and after the administration of muscle relaxant. RESULTS: Pdi (t) was reduced from (23.7?2.4) cmH 2O to (11.5?3.4) cmH 2O (reduction rate: 51.5%, P