Factors Influencing Ventilatory Muscle Recruitment in Patients with Chronic Airflow Obstruction

Abstract

Patients with chronic airflow obstruction (CAO) frequently develop abnormal thoraco-abdominal excursion, but the patterns described are inconsistent and the factors that relate to their development remain unknown. We studied 45 stable patients with FEV1 ranging from 0.36 to 2.1 L. A pattern of ventilatory muscle recruitment (VMR) was established by simultaneously measuring gastric (Pg) and pleural (Ppl) pressures and rib cage (Vrc) and abdominal (Vab) volume displacement with inductance plethysmography. From these tracings, Pg-Ppl plots were constructed and the delta Pg/delta Ppl values were calculated. The delta Pg/delta Ppl was validated in 15 patients with simultaneous analysis of Vab-Pg plots. Pearson's test and multiple regression analyses were used to correlate delta Pg/delta Ppl to factors thought to influence respiratory muscle function such as age, sex, nutritional status (weight/height, albumin), hyperinflation, airflow obstruction, and arterial blood gases. We found a direct correlation between a more positive delta Pg/delta Ppl value and increasing hyperinflation (r = 0.69, p less than 0.0001), increasing airflow obstruction (r = -0.55, p less than 0.001), and decreasing diaphragmatic strength (r2 = 0.32, p less than 0.001). We also found that expiratory Ppl became more positive with decreasing FEV1 (r2 = 0.33, p less than 0.001). This change in VMR was independent of age, sex, nutritional status, and arterial blood gas determinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Expiratory muscle pressure and breathing mechanics in chronic obstructive pulmonary disease

“…In all patients from the AE group, the expiratory muscle recruitment during expiration was consistent and was seen in every breath with little variation. The mean Pga,exp.rise of the group was 1.91 0.89 cmH 2 O with a range of 0.82±3.81 cmH 2 O in different patients. Table 1 shows the anthropometric and pulmonary function data for the two groups.…”

Controlled breathing and dyspnea in patients with chronic obstructive pulmonary disease (COPD)

“…Several studies have described an increase in rib cage contribution to chest wall motion and/or asynchrony between rib cage and abdominal motion in these patients [63][64][65]. The mechanisms underlying these alterations are not fully elucidated, but appear to be related to the degree of airflow obstruction, hyperinflation of the rib cage, changes in diaphragmatic function, and increased contribution of accessory inspiratory muscles to chest wall motion.…”

Efeitos de um programa de exercícios diafragmáticos de curta duração na mecânica respiratória e capacidade funcional de pacientes com DPOC: ensaio clínico controlado e aleatorizado

“…Portanto, é esperado que pacientes com DPOC apresentem um comprometimento da mobilidade diafragmática e uma redução de sua contribuição relativa no movimento tóraco-abdominal (Suga et al, 1999;Iwasawa et al, 2002;Dos Santos Yamaguti et al, 2008). Além disso, alguns estudos têm mostrado um aumento da atividade dos músculos respiratórios da caixa torácica como mecanismo compensatório da disfunção diafragmática (Martinez et al, 1990;De Andrade et al, 2005). Foi previamente demonstrado que tanto a redução da mobilidade diafragmática quanto a maior atividade dos músculos acessórios da respiração estão associadas com o aumento da dispnéia e intolerância ao exercício (Ward et al, 1988;Breslin et al, 1990;Paulin et al, 2007).…”

“…Os efeitos da hiperinsuflação pulmonar sobre os músculos inspiratórios têm sido mostrados em modelos experimentais realizados em animais (Decramer et al, 1987), em humanos saudáveis (Wolfson et al, 1983) e em pacientes com DPOC (Martinez et al, 1990). Em relação aos músculos intercostais, tem sido relatado que essa musculatura apresenta um encurtamento de apenas 7%…”

“…Tem sido relatado que a redução da eficiência do diafragma acarreta num inevitável aumento compensatório da atividade dos músculos da caixa torácica e músculos acessórios da ventilação (Martinez et al, 1990 (Duiverman et al, 2004;De Andrade et al, 2005).…”