Effects of Positive End‐Expiratory Pressure on Oscillated Volume during High‐Frequency Chest Compression in Children with Cystic Fibrosis

Abstract

OBJECTIVE:To investigate the effects of positive end-expiratory pressure (PEEP) on end-expiratory lung volume (EELV) and mean oscillated volume (V osc ) during high frequency chest compression (HFCC). DESIGN: A clinic-based prospective intervention study. SETTING: Pulmonary function laboratory, University of Alberta, Edmonton, Alberta. POPULATION: Nine children with cystic fibrosis with little or no obstructive airway disease who were selected from the outpatient Cystic Fibrosis and Pediatric Pulmonary Clinics at the University of Alberta Hospital, Edmonton, Alberta. METHODS: Each child received HFCC alone (at 10 Hz with chest wall pressure of 8 cm H 2 O) and HFCC plus PEEP. A closed circuit spirometry system was used to measure HFCC-and PEEP-induced changes in EELV, expressed as per cent baseline functional residual capacity (FRC) measured using helium dilution. An isothermic chamber permitted measurement of V osc . RESULTS: HFCC caused a significant 9% decrease in EELV. Adding 2.0±0.3 cm H 2 O of PEEP increased EELV back to at least the FRC level. With HFCC alone, V osc was significantly lower during spontaneous expiration than during spontaneous inspiration, but adding PEEP to HFCC increased V osc , especially during spontaneous expiration. CONCLUSIONS: Adding PEEP during HFCC prevents the decrease in EELV and increases V osc . Therefore, PEEP may improve HFCC-induced mucus clearance in children with cystic fibrosis. circuit fermé a été utilisé pour mesurer les modifications produites par la CTHF et la PEEP sur le VOM, exprimées à titre de pourcentage de la capacité résiduelle fonctionnelle (CRF) de base mesurée au moyen de dilution à l'hélium. Une chambre isothermique a permis de mesurer le VOM. RÉSULTATS : La CTHF a provoqué une diminution significative de 9 % du VEP. L'ajout de 2,0±0,3 cm d'H 2 O de PEEP a accru le VEP pour qu'il revienne au moins au taux de la CRF. Avec la simple CTHF, le VOM était beaucoup plus bas pendant l'expiration spontanée que pendant l'inspiration spontanée, mais l'ajout de PEEP à la CTHG faisait augmenter le VOM, surtout pendant l'expiration spontanée. CONCLUSIONS : L'ajout de la PEEP pendant la CTHF prévient la diminution du VEP et accroît le VOM. Par conséquent, la PEEP améliore peut-être la clairance muqueuse produite par la CTHF chez les enfants atteints de fibrose kystique. P atients with cystic fibrosis (CF) have viscous airway mucus that is difficult to clear from the lungs and that often plugs airways, causing air trapping (1). High frequency chest compression (HFCC) is a technique that increases mucus clearance in patients with CF after short term (2-4) or long term use (5).HFCC has comparable (6) or greater (7) effects on weight of expectorated sputum compared with conventional chest physiotherapy (CPT) and has the advantage of being self administered (6). Patients with CF have reported greater satisfaction and compliance using HFCC than with CPT (8).With HFCC, a pneumatic vest is worn that is inflated with air; the air pressure is then cycled at frequencies between 5 a...

High‐Frequency Chest Compression: A Summary of the Literature

“…Guerin et al (45) indicated that inspiratory airway resistance decreased with increasing lung volume from positive end-expiratory pressure. In 2003, Dosman et al (47) found that the addition of a small amount of positive end-expiratory pressure (2.0±0.3 cm H 2 O) during HFCC prevented the HFCC-induced decrease in endexpiratory lung volume and significantly increased the mean oscillated volume during expiration in pediatric patients with cystic fibrosis.…”

Effects of Changes in Lung Volume on Oscillatory Flow Rate During High‐Frequency Chest Wall Oscillation

“…al (14) found that a small amount of PEP, between 2 cm H 2 O and 3.7 cm H 2 O, maintained EELV at the level of FRC and it increased mean oscillated volume measured at the mouth in pediatric patients with CF (12) and in older patients with chronic obstructive pulmonary disease (COPD) (14). It was concluded that decreases in airway resistance, due to the PEP-induced increase in EELV (15), accounted for the increases in oscillated volume.…”

“…HFCWO has been demonstrated to decrease end-expiratory lung volume (EELV) to as much as 50% of the functional residual capacity (FRC) in patients with airway disease (10) due to the increased load applied to the chest wall (11). The decreased EELV was found to have a secondary effect on decreasing the HFCWO-induced oscillated volume in humans (10,12) and in dogs (11,13), but this effect can be reversed with the use of positive expiratory pressure (PEP) in combination with HFCWO. Dosman et al (12) and Perry et ©2007 Pulsus Group Inc. All rights reserved…”

Estrategias actuales en el manejo de las secreciones traqueobronquiales

“…50 Yuan y Dosman han empleado esta tecnología en pacientes pediátricos con problemas neurológicos (v.gr., parálisis cerebral y enfermedades neuromusculares); han informado un beneficio con menos fatiga y estancia hospitalaria con adecuada tolerancia. Otros escenarios clínicos están en proceso de ser analizados 51,52 (figura 4).…”