Positive end-expiratory pressure and pressure support in peripheral airways obstruction : work of breathing in intubated children.
OBJECTIVE
Children with peripheral airways obstruction suffer the negative effects of intrinsic positive end-expiratory pressure: increased work of breathing and difficulty triggering assisted ventilatory support. We examined whether external positive end-expiratory pressure to offset intrinsic positive end-expiratory pressure decreases work of breathing in children with peripheral airways obstruction. The change in work of breathing with incremental pressure support was also tested.


METHODS
Prospective clinical trial in a pediatric intensive care unit.


METHODS
Eleven mechanically ventilated, spontaneously breathing children with peripheral airways obstruction.


METHODS
Work of breathing (using pressure-rate product as a surrogate) was measured in three tiers: (a) Increasing pressure support over zero end-expiratory pressure. (b) Increasing applied positive end-expiratory pressure and fixed pressure support. The level of applied positive end-expiratory pressure at which pressure-rate product was least determined the compensatory positive end-expiratory pressure. (c) Increasing pressure support over compensatory (fixed) positive end-expiratory pressure.


RESULTS
Increases in pressure support alone decreased pressure-rate product from mean 724+/-311 to 403+/-192 cmH2O/min. Applied positive end-expiratory pressure alone decreased pressure-rate product from mean 608+/-301 to 250+/-169 cmH2O/min. The lowest pressure-rate product (136+/-128 cmH2O/min) was achieved using compensatory positive end-expiratory pressure (12+/-4 cmH2O) with pressure support 16 cmH2O.


CONCLUSIONS
For children with peripheral airways obstruction who require assisted ventilation, work of breathing during spontaneous breaths is decreased by the application of either compensatory positive end-expiratory pressure or pressure support.
Graham
Alan S
AS
Department of Pediatrics, Division of Pediatric Critical Care, Oregon Health and Science University, 707 S.W. Gaines Street, Portland, OR 97239-2901, USA. grahamal@ohsu.edu
Chandrashekharaiah
Girish
G
Citak
Agop
A
Wetzel
Randall C
RC
Newth
Christopher J L
CJ
D000402:Airway Obstruction / Q000503:physiopathology* / Q000628:therapy*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007442:Intubation, Intratracheal; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D014939:Work of Breathing