Cardiac Arrhythmias during Theophylline Toxicity: Methods (3)
Serum Theophylline Concentration Determination and Interpolation
Serum theophylline concentrations were determined using high pressure liquid chromatography (Hewlett-Packard, Waltham, MA) at MCV and a multiple chemistry analyzer that uses a fluorescence polarization immunoassay (Abbott TDX, Abbott Laboratories, North Chicago, IL) at MVAMC. Blood samples with markedly elevated STCs were serially diluted and tested again to optimize accuracy. The logarithm of each measured STC value was graphed on semi-log paper against the corresponding time the blood sample was obtained to estimate an approximate serum theophylline level for each hour of ECG recording. flovent inhaler
Data were expressed as mean±SD unless otherwise noted. Continuous data were analyzed using Students t tests unless the data had abnormal distribution, in which case the Wilcoxon ranked-sign test was used. Discontinuous data were tested using x2 analysis, unless fewer than five observations were present in any cell, in which case Fishers exact test was used. The relationship between STC and heart rate was examined using linear regression; p<0.05 was accepted as significant.