199 Metabolic alkalosis in patients with cystic fibrosis: Are we missing something?

Objectives Metabolic alkalosis is a recognised complication of CF. The condition appears to occur during both clinical stability and during pulmonary exacerbations. The aim of this study was to explore the relationship between metabolic alkalosis, clinical status and blood biochemistry. Methods A retrospective review of electronic patient records (2007–2013) was undertaken for all patients attending the Leeds Adult CF Unit who had a blood gas analysed. Demographic data, diabetic status, pancreatic status, CF liver disease, sputum microbiology and blood electrolytes were extracted for the most recent blood gas for each individual. Results A total of 568 samples were analysed from 124 subjects. Median age was 30 years (range 17–69). pH was normally distributed but the curve was shifted to the right with a median pH of 7.44 (range 7.1–7.66). Full data was available for 120 subjects. Reduced FEV1% (p ≤ 0.0001), elevated MRC dyspnoea score (p ≤ 0.0001), low BMI (p = 0.02), chronic Pseudomonas status (p<0.05) and use of intravenous antibiotics (p ≤ 0.01) were associated with higher blood gas bicarbonate levels. Although there was no association between bicarbonate and potassium, magnesium or sodium plasma levels, there was an inverse correlation with plasma chloride (r = –0.557, p<0.0001). Conclusion Metabolic alkalosis is a common complication of CF and is associated with worse clinical status, antibiotic therapy and reduced plasma chloride. The aetiology remains unclear and cannot be explained by simple electrolyte depletion. [ABSTRACT FROM AUTHOR]