Short-term effects of positive end-expiratory pressure on breathing pattern: an interventional study in adult intensive care patients.
BACKGROUND
Positive end-expiratory pressure (PEEP) is used in mechanically ventilated patients to increase pulmonary volume and improve gas exchange. However, in clinical practice and with respect to adult, ventilator-dependent patients, little is known about the short-term effects of PEEP on breathing patterns.


METHODS
In 30 tracheally intubated, spontaneously breathing patients, we sequentially applied PEEP to the trachea at 0, 5 and 10 cmH2O, and then again at 5 cmH2O for 30 s each, using the automatic tube compensation mode.


RESULTS
Increases in PEEP were strongly associated with drops in minute ventilation (P < 0.0001) and respiratory rate (P < 0.0001). For respiratory rate, a 1 cmH2O change in PEEP in either direction resulted in a change in rate of 0.4 breaths/min. The effects were exclusively due to changes in expiratory time. Effects began to manifest during the first breath and became fully established in the second breath for each PEEP level. Identical responses were found when PEEP levels were applied for 10 or 60 s. Post hoc analysis revealed a similar but stronger response in patients with impaired respiratory system compliance.


CONCLUSIONS
In tracheally intubated, spontaneously breathing adult patients, the level of PEEP significantly influences the resting short-term breathing pattern by selectively affecting expiratory time. These findings are best explained by the Hering-Breuer inflation/deflation reflex.
Haberthür
Christoph
C
Surgical Intensive Care Medicine, Department of Anaesthesia, Kantonsspital Luzern, Switzerland. christoph.haberthuer@ksl.ch
Guttmann
Josef
J
D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000378:metabolism; D003422:Critical Care / Q000379:methods*; D045853:Exhalation; D005260:Female; D006801:Humans; D001239:Inhalation; D007442:Intubation, Intratracheal; D008170:Lung Compliance; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods*; D015656:Respiratory Mechanics; D013990:Tidal Volume
D002245:Carbon Dioxide