[Continuous tracheal gas insufflation during pressure control ventilation with a pressure relief valve].
OBJECTIVE
To establish the method of continuous tracheal gas insufflation (CTGI) and investigate the role of pressure relief valve (PRV) in limiting high peak airway pressure induced by CTGI.


METHODS
CTGI device was made by authors. Nine healthy mongrel dogs were mechanically ventilated by using Evita 2 (Drager Inc.). PRV was inserted into the ventilatory circuit for selected experiment steps and adjusted a threshold pressure equal to the preset inspiratory pressure. PCV, PCV + CTGI (TGI group) and PCV + CTGI + PRV (PRV group) were conducted in different inspiration/expiration (I/E) ratio of 1:2 and 2:1. Gas exchange, lung mechanics and hemodynamics status were monitored at the constant set inspiratory pressure of PCV.


RESULTS
At the same I/E ratio, peak airway pressure in TGI group was higher than that of PRV and PCV group (P < 0.01), whereas PRV group maintained the preset inspiratory pressure as PCV group. At the different I/E ratio, peak airway pressure in TGI (2:1) group was higher than that of TGI (1:2) group(P < 0.01). PaCO2 in TGI and PRV group decreased significantly than that of PCV, TGI group was more lower than PRV group, PaO2, hemodynamics and oxygenation remained unchanged in all groups.


CONCLUSIONS
The CTGI device is effective in improving alveolar ventilation with no significant influence on hemodynamics and oxygenation; A pressure relief valve is necessary to ensure the safe use of CTGI.
Zhan
Q
Q
Beijing Institute of Respiratory Medicine, Beijing Red Cross Chaoyang Hospital, Capital University of Medical Sciences, Beijing 100020.
Wang
C
C
Shang
M
M
D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D007327:Insufflation / Q000379:methods*; D008297:Male; D008961:Models, Structural; D011312:Pressure; D012121:Respiration, Artificial; D012129:Respiratory Function Tests; D014132:Trachea / Q000502:physiology