Dynamic pulmonary hyperinflation and low grade systemic inflammation in stable COPD patients

It is increasingly recognized that a low grade of systemic inflammation occurs in patients with advanced chronic obstructive pulmonary disease (COPD). C-reactive protein (CRP), a marker of systemic chronic inflammatory response, has been related with decreased survival in large cohorts of COPD patients. The aim of the study was to assess if resting dynamic pulmonary hyperinflation (DH) is linked to the presence of systemic inflammation in COPD.

In a 12-month retrospective study involving 55 out-patients with COPD (FEV1 59+/- 23% pred.) examined in stable conditions, inspiratory capacity (IC) was measured at rest and considered as index of DH when lower than 80% predicted. Simultaneously, CRP (by immuno-turbidometry) and white blood cells (WBC), uric acid and alpha-1 globulins were measured in the venous blood in the morning before eating.

CRP was significantly increased in the COPD patients with IC < 80% pred. (n = 35; IC = 61 + 14% pred.) as compared with that measured in COPD patients with IC > 80% pred. (n = 20; IC = 97 + 13% pred.), amounting to 0.70 +/- 0.59 vs 0.29 +/- 0.28 mg/dl, respectively (p < 0.01). CRP was inversely related to IC (% pred.) (r = 0.45, p < 0.01). WBC, serum uric acid (an endogenous danger signal), and albumin and alfa-1 globulins were not different between the two groups.

These results show that the IC reduction is associated with higher serum levels of CRP in stable COPD patients, suggesting a potential role of dynamic pulmonary hyperinflation on development and maintenance of low grade systemic inflammation in COPD.