Most reports regarding unplanned extubation (UE) are case-control studies with matching age and disease severity. To avoid diminishing differences in matched factors, this study with only matching duration of mechanical ventilation aimed to re-examine the risk factors and the factors governing outcomes of UE in intensive care units (ICUs). This case-control study was conducted on 1,775 subjects intubated for mechanical ventilation. Thirty-seven (2.1%) subjects with UE were identified, and 156 non-UE subjects were randomly selected as the control group. Demographic data, acute Physiological and Chronic Health Evaluation II (APACHE II) scores, and outcomes of UE were compared between the two groups. Logistic regression analysis was used to identify the risk factors of UE. Milder disease, younger age, and higher Glasgow Coma Scale (GCS) scores with more frequently being physically restrained (all p<0.05) were related to UE. Logistic regression revealed that APACHE II score (odds ratio (OR) 0.91, p<0.01), respiratory infection (OR 0.24, p<0.01), physical restraint (OR 5.36, p<0.001), and certain specific diseases (OR 3.79–5.62, p<0.05) were related to UE. The UE patients had a lower ICU mortality rate (p<0.01) and a trend of lower in-hospital mortality rate (p = 0.08). Cox regression analysis revealed that in-hospital mortality was associated with APACHE II score, age, shock, and oxygen used, all of which were co-linear, but not UE. The results showed that milder disease with higher GCS scores thereby requiring a higher use of physical restraints were related to UE. Disease severity but not UE was associated with in-hospital mortality.

Exertional dyspnea scales (EDS) and health-related quality-of-life questionnaires (HRQoLQs) are used to assess chronic obstructive pulmonary disease (COPD). The GOLD guidelines categorize patients according to either 1 of these 2 domains, the lung function and the frequency of acute exacerbations in the preceding year, however with inconsistent results. Combining EDS and HRQoLQs may yield better results; however, the best combination is unclear. Whether the EDS quantifies the exercise capacity or the dyspnea perception is also unclear. The study was designed to correlate the EDS with exercise capacity and dyspnea perception and to evaluate the best combination of the EDS and HRQoLQ.Three EDS were compared by exercise capacity and Borg scores at rest and during exercise in 57 patients with COPD. Three HRQoLQs were compared by 4 domains of clinical assessments, and 2 types of exercise. The strength of correlation |r| was categorized by quartiles from <0.3 to ≥0.6.The EDS was better correlated with exercise capacities (|r| = 0.29–0.65, P < 0.05–<0.0001) than with the resting and exertional Borg scores (|r| = 0.08–0.55, P = NS- <0.0001). The EDS were moderately to strongly interrelated, but this correlation was weaker when including Oxygen-cost Diagram (OCD) (with the modified Medical Research Council, mMRC r = −0.56, with the baseline dyspnea index, BDI r = 0.49 vs. mMRC with BDI r = −0.73); however, the OCD had the strongest correlation with walking distance (r = 0.65, vs mMRC r = −0.59, BDI r = 0.5) and peak oxygen uptake (r = 0.39 vs mMRC r = −0.29, BDI r = 0.36). Among the HRQoLQs, the COPD assessment test (CAT) was most strongly correlated with the St. George Respiratory Questionnaire (SGRQ) (r = 0.77) and similar to the SGRQ regarding significant correlations with the other instruments (|r| = 0.29–0.67 vs. 0.36–0.77) but poorly with walking distance (r = −0.02). The OCD was mildly correlated with the CAT (r = −0.4).The EDS was more related to the exercise capacity than to the dyspnea perception and the CAT was most closely related to the other instruments but poorly with walking distance. The OCD can be used to compensate for this weak correlation. The study suggests using the CAT and the OCD simultaneously when undertaking clinical evaluation of patients with COPD.