Thirty-four patients with cystic fibrosis (CF) were assessed for baseline pulmonary functions before, and 5 and 15 minutes after cold air challenge (CACh). Most of the patients had no change in forced expiratory volume in 1 second (FEV1) and maximum expiratory flow at 25% vital capacity (Vmax25%VC) post-CACh. Five patients responded with reduced FEV1 and 13 with reduced Vmax25%VC. However, paradoxical increases were noted in 10 patients for FEV1 and in 5 for Vmax25%VC. Paradoxical responses were most frequent in patients with severe lung disease. The explanation for this variability may lie in the varying degrees of airway instability and volume of airway contribution (VAC) to early flows, resulting from the damage caused by chronic infection. Conventional challenges may be useless in determining the true incidence of bronchial hyperreactivity in patients with CF.

Adolescent↗

PubMedDate not supplied

Individualization of tobramycin dosage in patients with cystic fibrosis.

Tobramycin was administered to 52 patients, ages 2 months to 27 years, with cystic fibrosis during acute exacerbation of Pseudomonas-related pulmonary infection. Elimination pharmacokinetics of tobramycin was characterized for each patient after intravenous administration using a standardized infusion technique. The minimal inhibitory concentration was determined for Pseudomonas strains isolated from 26 of the 52 patients. The pharmacokinetic parameters of individual patient were used to adjust the dose and dosing interval to maintain the serum concentration of tobramycin above the minimal inhibitory concentration for the infecting organism for at least 75% of the dosing interval without exceeding the maximum concentration of 12 micrograms/ml or a minimum concentration of 2.0 micrograms/ml. This resulted in an increase of the mean daily dose of tobramycin to 12 mg/kg from an initial mean dose of 5.5 mg/kg and a reduction of the dosing interval from 8 hours to 4 or 6 hours for patients greater than 1 year of age. Significant differences between the pharmacokinetic profiles of the infants and older patients were observed.

Adolescent↗