Determination of specific molecular breath patterns by secondary electrospray ionization mass spectrometry (SESIHRMS) during and 8 weeks after a COPD exacerbation. Furthermore, breath patterns will be assessed for correlation and association with clinical outcomes and treatment.

Inclusion Criteria:

• Informed consent
• age >= 18 years
• staged according to GOLD recommendations
• GOLD stage 2-4, GOLD ABE classification
• hospitalization due to COPD exacerbation
• subjects adherent to triple inhalational therapy (beta-2-sympathomimetics, anticholinergics, steroids)
• suitable for follow-up assessment
• <48 hours after initiation of antibiotic therapy or systemic steroid therapy

Exclusion Criteria:

• physical or intellectual impairment precluding informed consent or protocol adherence
• known pregnancy
• congenital defects with direct impact on central metabolism e.g. amino acid metabolism defect
• uncontrolled diabetes (e.g. HbA1c >11% or Glc >20mmol/l)
• acute or chronic pulmonary disease other than COPD
• renal failure or renal replacement therapy (GFR < 15 mL/min)

Patients with COPD (staged according to GOLD recommendations, aged ≥18 years) on adherent triple inhalational therapy, hospitalized due to COPD exacerbation

Data of 28 participants were included in the final analysis as five patients withdrew their participation and the main outcome (breath analysis) of two participants was not analyzable.

Serious events were collected during study period between time of inclusion (acute COPD exacerbation) and follow-up visit at stable state approximately 8 weeks after inclusion.

Serious event were defined as follows:

Any unfavorable event where it cannot be excluded that the event is attributable to the sampling of biological material or the collection of health-related personal data, and which:

1. requires inpatient treatment not envisaged in the project plan or extends a current hospital stay;
2. results in permanent or significant incapacity or disability; or
3. is life-threatening or results in death.