Adaptive support ventilation for faster weaning in COPD: a randomised controlled trial.

Adaptive support ventilation (ASV) is a closed-loop ventilation mode that can act both as pressure support ventilation (PSV) and pressure-controlled ventilation. Weaning with ASV shows promising results, mainly in post-cardiac surgery patients. The aim of the present randomised controlled study was to test the hypothesis that weaning with ASV could reduce the weaning duration in patients with chronic obstructive pulmonary disease (COPD) when compared with PSV. From among 435 COPD patients admitted to the intensive care unit (ICU) during a 20-month period, 97 were enrolled. Patients were assigned at random to either ASV or PSV as a weaning mode. Compared with PSV, ASV provided shorter weaning times (median 24 (interquartile range 20-62) h versus 72 (24-144) h, p=0.041) with similar weaning success rates (35 out of 49 for ASV and 33 out of 48 for PSV). Length of stay in the ICU was also shorter with ASV but the difference was not statistically significant. This study suggests that ASV may be used in the weaning of COPD patients with the advantage of shorter weaning times. Further studies are needed to investigate the role and potential advantages of ASV in the weaning period of different patient groups.

Urinary uric acid excretion as an indicator of severe hypoxia and mortality in patients with obstructive sleep apnea and chronic obstructive pulmonary disease.

OBJECTIVE: Uric acid (UA) is the end product of adenosine triphosphate degradation, and could increase due to hypoxia. We investigated the association of UA metabolites with nocturnal hypoxemia, apnea-hypopnea index (AHI), noninvasive mechanical ventilation (NIMV) usage and five-year mortality. MATERIALS/SUBJECTS AND METHODS: We obtained urinary specimen before and after the night polysomnography in order to measure UA excretion and overnight change in urinary UA/creatinine ratio (ΔUA/Cr) in 75 subjects (14 controls, 15 chronic obstructive pulmonary disease (COPD) without nocturnal hypoxemia (NH), 15 COPD with NH, 16 obstructive sleep apnea syndrome (OSAS) without NH, 15 OSAS with NH). Percentage of time spent below SaO2 of 90% (T90%) for >10% of sleep time was considered as nocturnal hypoxemia. Patients were contacted after 5 years with a questionnaire including information on the use of NIMV treatment (n: 58) and urinary specimen analysis (n: 35). RESULTS: T90% was found to be significantly correlated with UA excretion (coefficient: 0.005, 95%CI: 0.003-0.007) and ΔUA/Cr (coefficient: 0.8, 95%CI: 0.3-1.2) after adjustments for age, gender, body mass index and apnea-hypopnea index. Median and IQR (interquartile range) of baseline UA excretion were 0.79 (0.51-0.89) and 0.41 (0.31-0.55) in 10 deceased and 58 surviving patients, respectively (p=0.001). UA excretion median and IQR of baseline and 5 years of NIMV treatment were 0.41 (0.36-0.57) and 0.29 (0.23-0.37), respectively (p=0.01). CONCLUSION: UA excretion, as a marker of tissue hypoxia, may be useful in the management of OSA and COPD patients.