During the clinical course of COPD, 2-3 acute
exacerbations per year are known to occur. These are
often precipitated by upper and/or lower respiratory
tract infections, exposure to environmental pollution
and in one-third of the cases no cause is apparent.
Each exacerbation may leave the patient with
worsening of symptoms and greater vulnerability to
further exacerbations and development of respiratory
failure and pulmonary hypertension.7-10 Long-term
follow-up studies show that in-hospital mortality in