Lung recoil and the determination of airflow limitation in cystic fibrosis and asthma

Abstract

A reduction of lung recoil pressure could aggravate any airflow limitation that might be present in patients with cystic fibrosis (CF) or asthma. In a group of 22 children and young adults (8 with cystic fibrosis, 8 with asymptomatic asthma, and 6 healthy controls) aged 8-24 years, lung recoil pressure (Pst) at 100%, 90%, and 60% of TLC and static lung compliance (Cst) were measured using an esophageal balloon. The indices of airflow limitation, including maximal expiratory flow at 25% VC (Vmax25), forced expiratory volume in 1 second (FEV1), and specific airway conductance (sGaw), were also measured. In all patients, Vmax25 was reduced, the airway obstruction being more pronounced in patients with CF. Pst was reduced in CF and asthma, again more in the patients with CF. Cst was normal in both groups because the pressure volume curve was shifted up and to the left. There were significant correlations between Pst at 60%, 90%, and 100% of TLC and both Vmax25 and FEV1 (P < 0.01). sGaw correlated with Pst90 and Pst60 (r = 0.47 and 0.53, respectively; P < 0.05 for both). No correlation was found between Cst and Pst at any lung volume. No correlations were observed between Cst and Vmax25, FEV1, or sGaw. These results suggest that loss of elastic lung recoil pressure is a factor in airflow limitation of children and young adults with CF or asthma.

Physiological and morphological determinants of maximal expiratory flow in chronic obstructive lung disease

“…Lung elastic recoil, airway conductance, and airway collapsibility are all important in the pathogenesis of airflow obstruction. Loss of lung elastic recoil pressure results in a reduction of the driving force to generate airflow, and is thought to decrease airway conductance secondary to a loss of the tethering forces that distend the airways [1,2,23]. Airflow obstruction correlated significantly with loss of lung elastic recoil pressure in the group of patients studied.…”

“…Maximal expiratory flow in COPD could be reduced by three different mechanisms. Firstly, loss of lung elastic recoil can decrease the driving pressure [1,2]. Secondly, inflammatory thickening and narrowing of airways can decrease the airway conductance upstream of flow-limiting segments.…”

Progression of pulmonary hyperinflation and trapped gas associated with genetic and environmental factors in children with cystic fibrosis

“…Previous investigations have demonstrated that pulmonary hyperinflation influences lung mechanics in terms of increased work of breathing, greater severity of breathlessness, impaired respiratory muscle function [53-58] and increased energy expenditure and oxygen consumption [55,56,59]. Recognition of functional deterioration is therefore critical to the ongoing management of patients with CF.…”

Effect of pattern of preceding inspiration on FEV1 in asthmatic children

“…In contrast, in asthmatic subjects, RV is determined by airway closure and, hence, it may be affected by increased airway stability that should accompany the increase in Pel,L during Manoeuvre No. 3 [20,21]. It has been shown that patients with emphysema have extensive collateral ventilation, which helps to preserve gas exchange [22].…”