The effect of back-up rate during non-invasive ventilation in young patients with cystic fibrosis.
OBJECTIVE
The aim of the study was to evaluate the effect of the back-up rate on respiratory effort during non-invasive mechanical ventilation.


METHODS
An in vitro study evaluated the inspiratory trigger in seven domiciliary ventilators. Then, a prospective, randomized, crossover trial compared the effect on respiratory effort of three different back-up rates during pressure support (PS) and assist-control/volume-targeted (AC/VT) ventilation.


METHODS
A research unit and a tertiary referral pediatric center.


METHODS
Ten patients with cystic fibrosis (CF).


METHODS
During the in vivo study, the back-up rate was progressively increased to the maximum that patients could tolerate (Fmax) and respiratory effort, as judged by pressure/time product of the diaphragm (PTPdi/min), was compared between the two ventilatory modes.


RESULTS
Differences were observed between trigger pressure, trigger time delay, trigger pressure/time product and the slope between flow and pressure in the seven ventilators. PS and AC/VT ventilation were associated with a decrease in respiratory effort (PTPdi/min was 518+/-172, 271+/-119 and 291+/-138 cmH(2)O. s(-1). min(-1), for spontaneous breathing, PS and AC/VT ventilation, respectively, p=0.05). During the two modes, increasing the back-up rate to Fmax resulted in a greater reduction in PTPdi/min (p=0.001), which was more pronounced during AC/VT ventilation, due to the automatic adjustment of the inspiratory/expiratory time ratio.


CONCLUSIONS
Increasing the back-up rate during PS and AC/VT ventilation decreases respiratory effort in young patients with CF, but this effect was more marked with AC/VT ventilation.
Fauroux
Brigitte
B
Pediatric Pulmonary Department and INSERM 213, Armand Trousseau Hospital, Assistance Publique-Hôpitaux de Paris, 28 avenue du Docteur Arnold Netter, 75012 Paris, France. brigitte.fauroux@trs.ap-hop-paris.fr
Louis
Bruno
B
Hart
Nicholas
N
Essouri
Sandrine
S
Leroux
Karl
K
Clément
Annick
A
Polkey
Michael Ian
MI
Lofaso
Frédéric
F
D000293:Adolescent; D000328:Adult; D002648:Child; D018592:Cross-Over Studies; D003550:Cystic Fibrosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008168:Lung / Q000503:physiopathology*; D008297:Male; D010366:Peak Expiratory Flow Rate; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics