Significance of serum uric acid in patients with chronic respiratory failure treated with non-invasive positive pressure ventilation.

PURPOSE:The aim of the study was to evaluate serum uric acid (UA) levels before and after non-invasive positive pressure ventilation (NPPV) to assess the utility of serum UA as an indicator of acute exacerbation of chronic respiratory failure (CRF) in patients treated with NPPV. METHODS:We analyzed change in the serum UA level in 29 patients with CRF due to restrictive thoracic disease and treated with NPPV. RESULTS:After NPPV therapy, PaO2 was significantly increased and PaCO2 was significantly decreased in all patients. Sixty-two percent of patients (18 of 29) showed a decreased serum UA/creatinine (Cr) ratio after NPPV therapy, but, overall, there was no significant change in serum UA/Cr (P=0.0688). The change in serum UA/Cr was not correlated with the changes in PaO2 and PaCO2 after NPPV. When we compared patients in whom serum UA/Cr decreased (n=18) with patients in whom serum UA/Cr did not decrease (n=11), there were significantly fewer patients who suffered CRF exacerbation in the group with a decrease (P=0.0021). Furthermore, the cumulative proportion (Kaplan-Meier) of patients who did not suffer exacerbation of CRF was significantly higher in the group in which serum UA/Cr decreased (P=0.0003). CONCLUSIONS:Our data suggest that serum UA may be a useful clinical indicator of CRF exacerbation in patients treated by NPPV.