Theophylline Disposition in Patients with COLD with and without Hypoxemia: Methods

The present study further investigated the effect of arterial blood gases on theophylline disposition. The experimental protocol differed from that of the earlier studies in two critical areas: first, the disposition of theophylline was assessed in the same patients with hypoxia and later on oxygen therapy, and second, theophylline and its three major metabolites were assayed in urine so as to document how hypoxia influenced theophylline biotransformation.

Methods
Subjects

The selection of the patients was based on the following two criteria: (1) hypoxic patients requiring oxygen therapy; and (2) patients presenting no obvious cause, other than the disease itself, able to alter theophylline disposition. Ten patients (nine men and one woman) with COLD were selected for the study. Special care was taken to exclude patients older than 70 years old, or patients with cor pulmonale, congestive heart failure or hepatic disease. None of the patients exhibited acute decompensation but rather a gradual deterioration of their ventilatory status. The patients did not smoke; however, three of them gave up smoking two, four, and five weeks before the admission to the hospital. this
Patients were hospitalized for clinical evaluation and possible oxygen therapy in the Respiratory Section of the C.H.U. de Brabois, Vandoeuvre-les-Nancy (France). Each candidate gave informed consent for inclusion in the study. Mean patients’ age was 58.2 ±3.1 years (± SEM) and their mean weight was 66.0 ±3.2 kg. Clinical data concerning the ventilatory status of the patients are shown in Table 1. Arterial blood gases, FVC, and FEV, were measured just prior theophylline administration, using an automated and computerized gas microanalyzer and an electronic spirometer, respectively.
Table 1—Mean (± SEM) Arterial Blood Gases and Ventilatory Function of Ten Patients with COLD

Before 02 Therapy After 02 Therapy
Heart rate, beats/min 75± 12 83±3
Respiratory rate, insp/min 20 ± 1 18 ± 1
Pa02, mm Hg 54.9± 1.3 73.6 ±1.9*
PaC02, mm Hg 46.4±2.3 49.3 ±3.2
pH 7.39 ±0.01 7.39 ±0.01
FVC, L 1.88±0.27 (4.18)f 1.76±0.27
FEV„ L 0.78 ±0.14 (2.91) 0.68±0.08
FEVj/FVC, % 40.7 ±2.7 (69.6) 40.2±3.5

Category: COLD

Tags: Hypoxemia, oxygen therapy, patients COLD, theophylline disposition