We evaluated whether the pathogens identified during acute exacerbation of chronic obstructive pulmonary disease (AE-COPD) are associated with the COPD medications used in the 6 months before AE-COPD. We collected the medical records of patients diagnosed with AE-COPD at 28 hospitals between January 2008 and December 2019 and retrospectively analyzed them. Microorganisms identified at the time of AE-COPD were analyzed according to the use of inhaled corticosteroid (ICS) and systemic steroid after adjusting for COPD severity. We evaluated 1177 patients with AE-COPD and available medication history. The mean age of the patients was 73.9 ± 9.2 years, and 83% were males. The most frequently identified bacteria during AE-COPD were Pseudomonas aeruginosa (10%), followed by Mycoplasma pneumoniae (9.4%), and Streptococcus pneumoniae (5.1%), whereas the most commonly identified viruses were rhinovirus (11%) and influenza A (11%). During AE-COPD, bacteria were more frequently identified in the ICS than non-ICS group (p = 0.009), and in the systemic steroid than non-systemic steroid group (p < 0.001). In patients who used systemic steroids before AE-COPD, the risk of detecting Pseudomonas aeruginosa was significantly higher during AE-COPD (OR 1.619, CI 1.007–2.603, p = 0.047), but ICS use did not increase the risk of Pseudomonas detection. The risk of respiratory syncytial virus (RSV) detection was low when ICS was used (OR 0.492, CI 0.244–0.988, p = 0.045). COPD patients who used ICS had a lower rate of RSV infection and similar rate of P. aeruginosa infection during AE-COPD compared to patients who did not use ICS. However, COPD patients who used systemic steroids within 6 months before AE-COPD had an increased risk of P. aeruginosa infection. Therefore, anti-pseudomonal antibiotics should be considered in patients with AE-COPD who have used systemic steroids.

Bronchiolitis obliterans (BO), which is associated with graft-versus-host disease after allogenic hematopoietic stem cell transplantation, is a major obstacle to survival after bone marrow transplantation due to its gradual progress, eventually leading to respiratory failure. Pumpless extracorporeal interventional lung assist (iLA) is effective in treatment of reversible hypercapnic respiratory failure. In this paper, we present a 23year-old female patient who underwent allogeneic peripheral blood stem cell transplantation (PBSCT) for acute lymphocytic leukemia. After 6 months, she complained of shortness of breath and was diagnosed with BO. Five months later, she developed an upper respiratory tract infection that worsened her BO and caused life-threatening hypercapnia. Since mechanical ventilation failed to eliminate CO2 effectively, iLA was applied as rescue therapy. Her hypercapnia and respiratory acidosis showed significant improvement within a few hours, and she was successfully weaned off iLA after 12 days. This is the first case report of iLA application for temporarily aggravated hypercapnia of PBSCT-associated BO followed by successful weaning. This rescue therapy should be considered in ventilator-refractory reversible hypercapnia in BO patients.