2012 Volume 16 Issue 1 Pages 13-19
An investigation was performed with regard to an optimum citric acid concentration for a cough test using a cough threshold for patients with dysphagia accompanying a primary disease.
The subjects of the investigation were 94 patients suspected of having dysphagia, aged from 21 to 92 years old (male: 64, female: 30, average age: 66 ± 13 years old), all of whom underwent Videoendoscopy (VE) or Videofluorography (VF), and also a cough test .
The patients inhaled a citric acid isotonic sodium chloride solution from a supersonic wave nebulizer for 1 min, and any resulting coughing was observed. The concentration was set so that coughing could be observed at least five times in a 1 min period of time, with a cough threshold of the subject being determined. If coughing occurred four times or less, the citric acid concentration was increased until coughing occurred five times, so that the cough test could be performed. The concentrations of citric acid used were 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0%. The specificity and sensitivity of the screening of silent aspiration (SA) were obtained from this data and an ROC curve was drawn up.
As a result of the VE/VF, the group with no aspiration or laryngeal penetration (no aspiration group) contained 43 patients, the aspiration group 30 patients, and the SA group 21 patients.
From this, the average of the overall cough threshold was 1.55±1.44%, and the cough thresholds from the results of the VE/VF were 1.26±1.25% in the no aspiration group, 1.21±1.03% in the aspiration group and 2.63 ± 1.78% in the SA group. Significant differences were found between the no aspiration group and the SA group, and between the aspiration group and the SA group.
The optimum citric acid concentration for the cough test was examined for the screening of SA, and as a result 1.0% was found to be the most suitable concentration. It was also revealed that the cough threshold of the SA group was significantly elevated in comparison with the thresholds of the no aspiration group and the aspiration group.
