FIG: 5: This Figure shows the results of a study about 18 years ago that looked for the predictive factors for hospitalization for acute exacerbations in 29 patients hospitalized for COPD.[5]  Some of the risk factors related to inadequate response to outpatient management; that is, the patients were refractory to optimal outpatient management, had severe breathlessness despite optimal management, or were at high risk of a comorbid condition (such as coronary artery disease).  Some of these patients’ symptoms were refractory to therapy and prolonged for 2 weeks or longer.

Some of the patients had altered mentation, and others had evidence of secondary pulmonary hypertension or worsening pulmonary function due to comorbid conditions such as heart failure superimposed on COPD. 

Impaired gas exchange was also important.  Patients who had worsening hypoxemia or new or worsening hypercapnia also had an increased risk for COPD hospitalization, meaning patients with a mean PaO2 of about 55 mmHg and a median of 50 mmHg, with mean and median PaCO2 levels about 61 and 55 mmHg, respectively. 

Abbreviations:  APACHE, acute physiology and chronic health evaluation; FIO2 , fraction of inspired oxygen; FIO2, 20% + (4 × O2 liter flow) in case of O2 delivery by nasal prongs (1); IQR, interquartile range (25th–75th percentiles). * Pneumonia in all 4 cases. † With or without oxygen therapy.