Physiological effects of decannulation in tracheostomized patients.
OBJECTIVE
To evaluate the physiological effects of decannulation on breathing patterns and respiratory mechanics by comparing mouth breathing (MB) to tracheal breathing (TB) in tracheostomized patients.


METHODS
Prospective cross-over study in a critical and neuromuscular care unit.


METHODS
Nine consecutive neuromuscular tracheostomized patients. Flow, esophageal pressure, gastric pressure, expiratory gas, and arterial blood gases were measured during MB and TB.


RESULTS
MB induced an increase in tidal volume (from 330+/-60 ml to 400+/-80 ml) without changing respiratory frequency, inspiratory time, or arterial CO(2) pressure. This ventilation increase was due to a significant increase in physiological dead space (from 156+/-67 to 230+/-82 ml) and was associated with significant increases in work of breathing (from 6.9+/-3.4 to 9.1+/-3.3 J/min), transdiaphragmatic pressure swing (from 10+/-4 to 12.5+/-7 cmH(2)O), diaphragmatic pressure-time product per minute (from 214+/-100 to 271+/-92 cmH(2)O s(-1) min(-1)), and oxygen uptake (from 206+/-30 to 229+/-34 ml/min). Upper airway resistance did not differ from in vitro tracheostomy tube resistance. In addition, total lung-airway resistance, dynamic pulmonary compliance, and intrinsic positive end-expiratory pressure were similar in both conditions.


CONCLUSIONS
Decannulation resulted in a dead space increase with no other detectable additional loading. It increased work of breathing by more than 30%. Decannulation deserves special attention in patients with restrictive respiratory disease.
Chadda
Karim
K
Service de Réanimation Médicale, Hôpital Raymond Poincaré, Assistance Publique-Hôpitaux de Paris, 92380 Garches, Paris, France.
Louis
Bruno
B
Benaïssa
Lamine
L
Annane
Djillali
D
Gajdos
Philippe
P
Raphaël
Jean Claude
JC
Lofaso
Frédéric
F
D000293:Adolescent; D000328:Adult; D000368:Aged; D000403:Airway Resistance; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000378:metabolism; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008170:Lung Compliance; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D018467:Positive-Pressure Respiration, Intrinsic; D011312:Pressure; D011446:Prospective Studies; D012126:Respiratory Dead Space; D015656:Respiratory Mechanics / Q000502:physiology*; D018709:Statistics, Nonparametric; D014139:Tracheostomy; D015300:Ventilator Weaning; D014939:Work of Breathing
D002245:Carbon Dioxide