Background This thesis investigates the effect of sodium modification on asthma and heart rate variability (HRV) using a randomised controlled study design. Cross-sectional data were used to assess novel markers of asthma control and if serum osmolality was inversely associated with lung function. Methods and Results The effect of dietary sodium modification on asthma control and HRV The study design was a randomised placebo-controlled double-blind study of participants aged 18-65 years old with asthma and measurable bronchial reactivity. The intervention involved adopting a low sodium diet for six weeks. 199 participants provided measures of asthma control and 29 participants provided 24-hour electrocardiographic measurements at baseline and six weeks later. There were no differences between those allocated to the low and normal sodium diet groups in any of the measures of asthma control or HRV. Bronchoconstriction induced by deep inspiration and exhaled carbon monoxide as surrogate marker of asthma control Serial PEFR measures were provided by 127 individuals to measure bronchoconstriction after deep inhalation and 182 individuals provided measurements of eCO. The relationship between these measures and asthma control was assessed. There was no relationship between either bronchoconstriction after deep inspiration or eCO and asthma control. Serum osmolality and lung function The NHANES III database was used to investigate if serum osmolality was cross-sectionally associated with lung function. In 13,602 individuals a SD increase in serum osmolality was associated with a decrease in FEV1 of 19.8ml (95% CI; -30.3 to -9.3) and FVC of 35.3ml (95% CI; -47.9 to -22.7). Conclusions A low sodium diet did not improve asthma control or increase heart rate variability in adults with asthma. Bronchoconstriction to deep inspiration and measurements of eCO have limited potential as markers of asthma control. In the NHANES dataset, increased serum osmolality was associated with decreased lung function.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:514716 |
| Date | January 2009 |
| Creators | Pogson, Zara |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/10626/ |
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