RESUMO Pressão Expiratória Positiva (PEwP) melhora a função pulmonar, entretanto, as mudanças induzidas pela PEP não estão totalmente estabelecidas. O objetivo do estudo foi avaliar os efeitos agudos de diferentes intensidades de PEP nos volumes da parede torácica (PT) e padrão respiratório em crianças com Fibrose Cística (FC). Dados antropométricos, função pulmonar e força da musculatura respiratória. Os volumes da PT foram avaliados através da Pletismografia Optoeletrônica (POE) em repouso e durante o uso de diferentes intensidades de PEP (10 e 20 cm H2O). Foram recrutados 8 sujeitos com FC (5H; 11,5 ± 3,2 anos; 32 ± 9,5 kg) e 7 sujeitos (4H; 10,7 ± 1,5 anos; 38,2 ± 7,8 kg). Grupo FC mostrou valores significativamente menores para FEF 25-75% (FC: 1,8 ± 0,8 vs. GC: 2,3 ± 0,6) e relação VEF1/CVF (FC: 0,8 ± 0,1 vs. GC: 1 ± 0,1) comparado ao grupo controle (p>0,05). Diferentes intensidades de PEP levaram a um aumento do volume corrente da PT e seus compartimentos em ambos os grupos, entretanto, este volume aumentou de forma significativa no grupo controle quando comparado ao grupo FC durante PEP20 (CW: 0,77 ± 0,25 L vs. 0,44 ± 0,16 L; RCp: 0,3 ± 0,13 L vs. 0,18 ± 0,1 L; RCa: 0,21 ± 0,1 L vs. 0,12 ± 0,1 L; AB: 0,25 ± 0,1 L vs. 0,15 ± 0,1 L; p>0,05 para todas as variáveis). A ventilação minuto aumentou de forma significativa durante a PEP em comparação a respiração em repouso para ambos os grupos (p>0,005). Volume expiratório final também foi maior durante a PEP em comparação a respiração em repouso para PT e caixa torácica pulmonar em ambos os grupos (p>0,05). Diferentes intensidades de PEP podem induzir aumentos nos volumes da parede torácica em pacientes com FC.

ABSTRACT Positive Expiratory Pressure (PEP) improves lung function, however, PEP-induced changes are not fully established. The aim of this study was to assess the acute effects of different PEP levels on chest wall volumes and the breathing pattern in children with Cystic Fibrosis (CF). Anthropometric data, lung function values, and respiratory muscle strength were collected. Chest wall volumes were assessed by Optoelectronic plethysmography at rest and during the use of different PEP levels (10 and 20 cm H2O), randomly chosen. Eight subjects with CF (5M, 11.5±3.2 years, 32±9.5 kilograms) and seven control subjects (4M, 10.7±1.5 years, 38.2±7.8 kilograms) were recruited. The CF group showed significantly lower FEF values 25-75% (CF: 1.8±0.8 vs. CG: 2.3±0.6) and FEV1/FVC ratio (CF: 0.8±0.1 vs. CG: 1±0.1) compared with the control group (p<0.05). Different PEP levels increased the usual volume in chest wall and its compartments in both groups; however, this volume was significantly higher in the control group compared with the CF group during PEP20 (CW: 0.77±0.25 L vs. 0.44±0.16 L; RCp: 0.3±0.13 L vs. 0.18±0.1 L; RCa: 0.21±0.1 L vs. 0.12±0.1 L; AB: 0.25±0.1 L vs. 0.15±0.1 L; p<0.05 for all variables). Minute ventilation was significantly higher during PEP compared with breathing at rest in both groups (p<0.005). End-expiratory volume was also higher during PEP compared with breathing at rest for chest wall and pulmonary rib cage in both groups (p<0.05). Different PEP levels may increase chest wall volumes in CF patients.

RESUMEN La Presión Espiratoria Positiva (PEP) mejora la función pulmonar, mientras tanto, los cambios inducidos por la PEP no están totalmente establecidos. El objetivo del estudio fue evaluar los efectos agudos de distintas intensidades de PEP en los volúmenes de la pared torácica (PT) y patrón respiratorio en niños con Fibrosis Cística (FC). Datos antropométricos, función pulmonar y fuerza de la musculatura respiratoria. Los volúmenes de la PT fueron evaluados a través de la Pletismografía Optoelectrónica (POE) en reposo y durante el uso de distintas intensidades de PEP (10 y 20 cm H2O). Fueron reclutados 8 sujetos con FC (5H; 11,5 ± 3,2 años; 32 ± 9,5 kg) y 7 sujetos (4H; 10,7 ± 1,5 años; 38,2 ± 7,8 kg). Grupo FC mostró valores significativamente menores para FEF 25-75% (FC: 1,8 ± 0,8 vs. GC: 2,3 ± 0,6) y relación VEF1/CVF (FC: 0,8 ± 0,1 vs. GC: 1 ± 0,1) comparado al grupo control (p>0,05). Distintas intensidades de PEP conllevaron a un incremento del volumen corriente de la PT y sus compartimentos en ambos los grupos, mientras tanto, este volumen incrementó de manera significativa en el grupo control cuando comparado al grupo FC durante PEP20 (CW: 0,77 ± 0,25 L vs. 0,44 ± 0,16 L; RCp: 0,3 ± 0,13 L vs. 0,18 ± 0,1 L; RCa: 0,21 ± 0,1 L vs. 0,12 ± 0,1 L; AB: 0,25 ± 0,1 L vs. 0,15 ± 0,1 L; p>0,05 para todas las variables). La ventilación minuto incrementó de manera significativa durante la PEP en comparación a la respiración en reposo para ambos grupos (p>0,005). El volumen espiratorio final también fue más grande durante la PEP en comparación a la respiración en reposo para PT y la caja torácica pulmonar en ambos los grupos (p>0,05). Las distintas intensidades de PEP pueden inducir incrementos en los volúmenes de la pared torácica en pacientes con FC.

BACKGROUND: Cystic fibrosis (CF) is a multisystem disease that affects the cardiorespiratory system and the cardiac autonomic control may be altered at rest and after a submaximal exercise. OBJECTIVE: To assess the cardiac autonomic control by heart rate variability (HRV) analysis before and after a 6-minute walk test (6MWT). METHOD: Thirteen children diagnosed with Cystic Fibrosis (CFG) aged 12±2.7 years (FEV1/FVC: 0.83±0.11, FEV1: 71.4±21 %pred) and 12 healthy children (control group-CG) aged 11.4±2.4 years (FEV1/FVC: 0.91±0.12, FEV1: 91.6±17.4 %pred) were included in the study. HRV was evaluated prior to and immediately after the 6MWT and the heart rate recovery assessed on the first and second minute after test. RESULTS: Prior to exercise, CF patients presented higher values for the variables LFnu (53.2±15.0 vs. 32.8±7.9, p=0.0003) and LF/HF (1.25±0.72 vs. 0.49±0.18, p<0.006) as well as lower values of HF% (25.4±18.4 vs. 53±9.6, p=0.002) and HFnu (47.3±14.7 vs. 68.3±8.7, p0.001) when compared to CG. After the 6MWT, both groups demonstrated HRV recovery to baseline levels; however, the differences between CFG and CG were maintained for the variables LF(ms 2) (846.7±754.8 vs. 345.6±197.2, p=0.02); LF% (35.4±8.1 vs. 25.9±6.2, p=0.002); LFnu (60.0±16.3 vs. 34.9±8.7, p<0.0001); HF% (27.4±13.7 vs. 48.1±6.3, p=0.0003); HFnu (40.4±15.8 vs. 65.6±8.2, p=0.0003) and LF/HF (1.9±1.7 vs. 0.5±0.2, p=0.0001). CONCLUSIONS: Children with cystic fibrosis exhibited predominance of sympathetic activity at rest that persisted after the 6-minute walking test when compared to the control group.