Flow-triggering reduces inspiratory effort during weaning from mechanical ventilation.
OBJECTIVE
To investigate whether a new flow-triggered (FT) system can reduce the patient's inspiratory effort compared to a traditional pressure-triggered (PT) system during weaning from mechanical ventilation.


METHODS
Prospective study.


METHODS
Intensive care unit of a General Hospital.


METHODS
10 mechanically ventilated patients, without chronic airway disease, ready to wean.


METHODS
Minute ventilation, breathing pattern, lung mechanics, inspiratory work of breathing (WI) and pressure time product (PTP) of Ppl were obtained in two conditions: 1) unsupported spontaneous breathing through the ventilator circuit (SB); 2) spontaneous breathing with continuous positive airway pressure set at 5 cmH2O (CPAP). Two triggering systems, namely PT and FT, were used in each condition.


RESULTS
Though there was no change in breathing pattern, minute ventilation, and lung mechanics, the magnitude of the inspiratory effort decreased significantly with FT compared to PT in both instances. The added resistance (total flow resistance minus pulmonary resistance) decreased by 37% on average when FT replaced PT. PTP decreased, on average, 27% and 15% during SB and CPAP, respectively, with FT compared to PT (p < 0.05). A similar significant decrease was observed in WI.


CONCLUSIONS
The new FT system, i.e. flow-by system, reduces the unintentional ventilatory workload upon the patients' inspiratory muscles compared to traditional PT system during weaning from mechanical ventilation.
Polese
G
G
Service of Pneumotisiology, ULSS 25, Verona, Italy.
Massara
A
A
Poggi
R
R
Brandolese
R
R
Brandi
G
G
Rossi
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000295:instrumentation*; D011446:Prospective Studies; D012123:Pulmonary Ventilation; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics; D012132:Respiratory Muscles; D015300:Ventilator Weaning / Q000295:instrumentation*; D014939:Work of Breathing