Respiratory effects of tracheal gas insufflation in spontaneously breathing COPD patients.
OBJECTIVE
To evaluate the effect of tracheal gas insufflation (TGI) in spontaneously breathing, intubated patients with chronic obstructive pulmonary disease (COPD) undergoing weaning from the mechanical ventilation.


METHODS
A prospective study in humans.


METHODS
Polyvalent intensive care unit (14-bed ICU) in a 700-bed general university hospital.


METHODS
Twelve patients with chronic obstructive pulmonary disease (COPD) who required intubation and mechanical ventilation were studied. All patients met standard criteria for weaning from mechanical ventilation. Seven patients (group 1) had been transorally intubated during episodes of acute respiratory failure. Five patients, all men (group 2), had previously undergone tracheostomy and had a transtracheal tube in place.


METHODS
Intratracheal, humidified, O2-mixture insufflation (TGI) was given via a catheter placed in distal or proximal position. Gas delivered through the intratracheal catheter was blended to match the fractional of inspired gas through the endotracheal tube. Continuous flows of 3 and 6 l/min in randomized order were used in each catheter position. Prior to data collection at each stage, an equilibration period of at least 30 min was observed, and thereafter blood gases were analyzed every 5 min. A new steady state was assumed to have been established when values of both PaCO2 and V CO2 changed by less than 5% between adjacent measurements. The last values of blood gases were taken as representative. The new steady state was confirmed within 35-50 min. Baseline measurements with zero Vcath were made at the beginning and end of the experiment.


RESULTS
This study shows that VT, MV, PaCO2, and VD/VT are reduced in a flow-dependent manner when gas is delivered through an oral-tracheal tube (group 1). The distal catheter position was more effective than the proximal one. In contrast, when gas was delivered through tracheostomy (group 2), TGI was ineffective in the proximal position and less effective than in group 1 in distal position.


CONCLUSIONS
Under the experimental conditions, tracheal gas insufflation decreased dead space, increased alveolar ventilation and possibly reduced work of breathing. From the preliminary data reported here, we believe that TGI may help patients experiencing difficulty during weaning.
Nakos
G
G
Intensive Care Medicine Department, University Hospital of Ioannina, Greece.
Lachana
A
A
Prekates
A
A
Pneumatikos
J
J
Guillaume
M
M
Pappas
K
K
Tsagaris
H
H
D000208:Acute Disease; D000368:Aged; D005260:Female; D006801:Humans; D007327:Insufflation / Q000379:methods*; D008173:Lung Diseases, Obstructive / Q000150:complications*; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012131:Respiratory Insufficiency / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D013990:Tidal Volume; D014139:Tracheostomy; D015300:Ventilator Weaning / Q000379:methods*; D014939:Work of Breathing