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.