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Open Access

Effects of change in the expiratory trigger during pressure support ventilation in COPD

  • D Chiumello1,
  • N Raimondi2,
  • M Cressoni1,
  • F Polli1,
  • S Terragni1,
  • R Colombo2,
  • E Ballone2 and
  • F Tallarini1
Critical Care200610(Suppl 1):P39

Published: 21 March 2006


OxygenPublic HealthEmergency MedicineRespiratory FailurePressure Time


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.


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.


See Table 1.
Table 1

(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

Statistically significant


The change of percentage of ET at a low level of PSV did not modify the inspiratory effort and pattern of breathing.

Authors’ Affiliations

Policlinico IRCCS, Milano, Italy
Sacco Hospital, Milano, Italy


© Biomed central limited 2001