Measurement of glucose in tracheobronchial secretions to detect aspiration of enteral feedings

OBJECTIVES: To determine (1) the relationship between results from 2 methods to measure glucose in tracheobronchial aspirates, (2) the effect of blood glucose levels on tracheobronchial glucose levels, and (3) the relationship between results from 2 methods to measure glucose in selected enteral formulas. DESIGN: Descriptive. SETTING: Two midwestern acute-care hospitals, a research laboratory, and a clinical laboratory. PATIENTS: Sixty-two acutely ill adult subjects with artificial airways whose secretions required frequent suctioning for therapeutic purposes; 53 of these 62 patients also required capillary blood glucose measurements for therapeutic purposes. OUTCOME MEASURES: Glucose concentrations in tracheobronchial secretions, capillary blood, and selected enteral formulas. INTERVENTION: None. RESULTS: Measures of glucose content made on 75 split samples of tracheobronchial secretions by 2 methods (glucose oxidase reagent strips and a laboratory assay) were highly correlated (r = 0.94; P <.001) and mean readings were not statistically different (P =.17). Sixty-six capillary blood glucose readings made within 5 minutes of tracheobronchial suctioning correlated poorly with the glucose content in the tracheobronchial aspirates (r = 0.12; P =.36). Glucose concentrations in 22 enteral formulas determined by 2 methods correlated highly (r = 0.95; P <.001). Glucose concentrations were higher with the laboratory assay (259.6 +/- 206.3 mg/dL) than with glucose oxidase reagent strips (188.6 +/- 157.5 mg/dL). CONCLUSION: It appears appropriate to use glucose oxidase reagent strips to estimate glucose concentrations in tracheobronchial fluid. Elevated blood glucose levels apparently do not have a major effect on the glucose content in tracheobronchial fluid. Although mean glucose concentrations in the 22 formulas were higher with the laboratory assay, the readings were sufficiently similar to allow using glucose oxidase reagent strips to give a good estimation of the formulas' glucose content.