Effects of change in the expiratory trigger during pressure support ventilation in COPD
Published: 21 March 2006
Keywords
Introduction
During pressure support ventilation (PSV) the ventilator cycles from inspiration to expiration when the inspiratory flow reaches a given percentage of the peak inspiratory flow 'expiratory trigger' (ET). On the most recent available ventilators it is possible to modify the percentage of the ET.
Objective
We evaluated in a group of COPD patients during PSV the change of ET (high 40% and low 5% of the peak inspiratory flow, respectively) in terms of the pattern of breathing and inspiratory effort (pressure time product [PTP]).
Materials and methods
Nine COPD patients were studied during respiratory failure (PaO2/FiO2 295 ± 108, PEEP 6.2 ± 1.7 cmH2O, mean age 70 ± 2 years, and BMI 25.4 ± 4.3). PSV was set at 5 cmH2O without PEEP while the oxygen fraction remained constant during the study. Airway, esophageal, gastric pressures and airflow were measured.
Results
(abstract P39
Respiratory rate (bpm) | Tidal volume (ml) | Cycling flow (l/s) | PTP (cmH2O*s*min) | |
|---|---|---|---|---|
Low ET | 26.6 ± 7.5 | 361 ± 118 | 0.04 ± 0.01 | 313 ± 81 |
High ET | 26.4 ± 8.1 | 352 ± 93 | 0.17 ± 0.04† | 284 ± 85 |
Conclusion
The change of percentage of ET at a low level of PSV did not modify the inspiratory effort and pattern of breathing.
