Within-breath respiratory impedance and airway obstruction in patients with chronic obstructive pulmonary disease

OBJECTIVE: Recent work has suggested that within-breath respiratory impedance measurements performed using the forced oscillation technique may help to noninvasively evaluate respiratory mechanics. We investigated the influence of airway obstruction on the within-breath forced oscillation technique in smokers and chronic obstructive pulmonary disease patients and evaluated the contribution of this analysis to the diagnosis of chronic obstructive pulmonary disease. METHODS: Twenty healthy individuals and 20 smokers were assessed. The study also included 74 patients with stable chronic obstructive pulmonary disease. We evaluated the mean respiratory impedance (Zm) as well as values for the inspiration (Zi) and expiration cycles (Ze) at the beginning of inspiration (Zbi) and expiration (Zbe), respectively. The peak-to-peak impedance (Zpp=Zbe-Zbi) and the respiratory cycle dependence (ΔZrs=Ze-Zi) were also analyzed. The diagnostic utility was evaluated by investigating the sensitivity, the specificity and the area under the receiver operating characteristic curve. ClinicalTrials.gov: NCT01888705. RESULTS: Airway obstruction increased the within-breath respiratory impedance parameters that were significantly correlated with the spirometric indices of airway obstruction (R=−0.65, p<0.0001). In contrast to the control subjects and the smokers, the chronic obstructive pulmonary disease patients presented significant expiratory-inspiratory differences (p<0.002). The adverse effects of moderate airway obstruction were detected based on the Zpp with an accuracy of 83%. Additionally, abnormal effects in severe and very severe patients were detected based on the Zm, Zi, Ze, Zbe, Zpp and ΔZrs with a high degree of accuracy (>90%). CONCLUSIONS: We conclude the following: (1) chronic obstructive pulmonary disease introduces higher respiratory cycle dependence, (2) this increase is proportional to airway obstruction, and (3) ...

Hiperinsuflação manual combinada com compressão torácica expiratória para redução do período de internação em UTI em pacientes críticos sob ventilação mecânica / Manual hyperinflation combined with expiratory rib cage compression for reduction of length of ICU stay in critically ill patients on mechanical ventilation

OBJETIVO: Embora a hiperinsuflação manual (HM) seja largamente usada para a remoção de secreções pulmonares, não há evidências para sua recomendação como rotina na prática clínica. O objetivo do estudo foi avaliar o efeito da HM combinada com compressão torácica expiratória (CTE) na duração de internação em UTI e no tempo de ventilação mecânica (VM) em pacientes sob VM. MÉTODOS: Ensaio clínico prospectivo, randomizado e controlado com pacientes de UTI sob VM em um hospital acadêmico terciário entre janeiro de 2004 e janeiro de 2005. Dentre os 49 pacientes que preencheram os critérios do estudo, 24 e 25 foram randomicamente alocados nos grupos fisioterapia respiratória (FR) e controle, respectivamente, sendo que 6 e 8 foram retirados do estudo. Durante o período de observação de 5 dias, os pacientes do grupo FR receberam HM combinada com CTE, enquanto os controles receberam o tratamento padrão de enfermagem. RESULTADOS: Os dois grupos apresentaram características basais semelhantes. A intervenção teve efeito positivo na duração de VM, alta da UTI e escore de Murray. Houve diferenças significativas entre os grupos controle e FR em relação à taxa de sucesso no desmame nos dias 2 (0,0% vs. 37,5%), 3 (0,0% vs. 37,5%), 4 (5,3 vs. 37,5%) e 5 (15,9% vs. 37,5%), assim como à taxa de alta da UTI nos dias 3 (0% vs. 25%), 4 (0% vs. 31%) e 5 (0% vs. 31%). No grupo FR, houve uma melhora significante no escore de Murray no dia 5. CONCLUSÕES: Nossos resultados mostraram que o uso combinado de HM e CTE por 5 dias acelerou o processo de desmame e de alta da UTI.

OBJECTIVE: Although manual hyperinflation (MH) is widely used for pulmonary secretion clearance, there is no evidence to support its routine use in clinical practice. Our objective was to evaluate the effect that MH combined with expiratory rib cage compression (ERCC) has on the length of ICU stay and duration of mechanical ventilation (MV). METHODS: This was a prospective randomized controlled clinical trial involving ICU patients on MV at a tertiary care teaching hospital between January of 2004 and January of 2005. Among the 49 patients who met the study criteria, 24 and 25 were randomly assigned to the respiratory physiotherapy (RP) and control groups, respectively. Of those same patients, 6 and 8, respectively, were later withdrawn from the study. During the 5-day observation period, the RP patients received MH combined with ERCC, whereas the control patients received standard nursing care. RESULTS: The two groups were similar in terms of the baseline characteristics. The intervention had a positive effect on the duration of MV, as well as on the ICU discharge rate and Murray score. There were significant differences between the control and RP groups regarding the weaning success rate on days 2 (0.0% vs. 37.5%), 3 (0.0% vs. 37.5%), 4 (5.3% vs. 37.5%), and 5 (15.9% vs. 37.5%), as well as regarding the ICU discharge rate on days 3 (0% vs. 25%), 4 (0% vs. 31%), and 5 (0% vs. 31%). In the RP group, there was a significant improvement in the Murray score on day 5. CONCLUSIONS: Our results show that the use of MH combined with ERCC for 5 days accelerated the weaning process and ICU discharge.

Total inspiratory and expiratory impedance in patients with severe chronic obstructive pulmonary disease

OBJECTIVES: Several studies have confirmed the high potential of the forced oscillation technique for the assessment of respiratory modifications related to chronic obstructive pulmonary disease. However, most of these studies did not employ within-breath analyses of the respiratory system. The aim of this study is to analyze respiratory impedance alterations in different phases of the respiratory cycle of chronic obstructive pulmonary disease patients and to evaluate their clinical use. METHODS: 39 individuals were evaluated, including 20 controls and 19 individuals with chronic obstructive pulmonary disease who experienced severe airway obstruction.Weevaluated the mean respiratory impedance (Zm) as well as values for inspiration (Zi) and expiration cycles (Ze), at the beginning of inspiration (Zbi) and expiration (Zbe). The peak-to-peak impedance (Zpp), and the impedance change (DZrs) were also analyzed. The clinical usefulness was evaluated by investigating the sensibility, specificity and the area under the receiver operating characteristic curve. RESULTS: The respiratory impedance increased in individuals with chronic obstructive pulmonary disease in all of the studied parameters (Zm, Zi, Ze, Zbi, Zbe, DZrs and Zpp). These changes were inversely associated with spirometric parameters. Higher impedanceswere observed in the expiratory phase of individualswith chronic obstructive pulmonary disease. All of the studied parameters, except for DZrs (area under the receiver operating characteristic ,0.8), exhibited high accuracy for clinical use (area under the receiver operating characteristic .0.90; Sensibility $ 0.85; Sp $ 0.85). CONCLUSIONS: The respiratory alterations in severe chronic obstructive pulmonary disease may be identified by the increase in respiratory system impedance, which is more evident in the expiratory phase. These results confirm the potential of within-breath analysis of respiratory impedance for the assessment of respiratory modifications related to chronic obstructive pulmonary disease.