Effects of Aminophylline on Diaphragmatic Dysfunction after Upper Abdominal Surgery

Abstract

The effects of upper abdominal surgery on diaphragmatic function were studied in 8 supine patients before and after administration of aminophylline. Changes in pleural (.DELTA.Ppl) and gastric pressure (.DELTA.Pga) swings were measured with balloon catheter systems. Transdiaphragmatic pressure change (.DELTA.Pdi) was calculated as the difference .DELTA.Pga-.DELTA.Ppl. The ratio .DELTA.Pga/.DELTA.Pdi, used as an index of the diaphragmatic contribution to the quiet breathing process, decreased significantly as early as 1 h after operation without any further change throughout the 6-h period studied. Administration of aminophylline (6 mg/kg), 6 h postoperatively, produced a significant increase in this diaphragmatic index. The early reduced diaphragmatic activity, after upper abdominal surgery, partially may be reversed by administration of aminophylline. The mechanism of its action may involve central nervous stimulation and/or a direct inotropic effect on diaphragmatic muscle. Further studies are needed to evaluate if the correction of altered diaphragmatic motion by aminophylline improves postoperative lung function.