Effect of digoxin on global respiratory muscle strength after cholecystectomy: a double blind study

Background-Upper abdominal surgery has been shown to impair the function of the respiratory muscles. In addition, controversial results have been repo rted concerning the effect of digoxin on the diaphragm. The aim of this stu dy was to investigate further the mechanism(s) of respiratory muscle dysfun ction after cholecystectomy and the effect of digoxin on the impaired respi ratory muscle function. Methods-Twenty three patients (four men) were studied before and 48 hours a fter surgery. Eleven received digoxin and 12 placebo. Respiratory muscle st rength was assessed 48 hours after surgery by measuring mouth pressure duri ng maximum static inspiratory (PImax) and expiratory (PEmax) efforts before and after 90 minutes of intravenous administration of 0.25 mg digoxin in a double blind, placebo controlled fashion. In addition, spirometric and pai n measurements were performed. Results- Postoperatively (+48 h) PImax and PEmax decreased significantly (p < 0.01) from their preoperative values in both groups by a similar degree. After administration of digoxin or placebo only the digoxin group showed a significant increase in both PImax (p < 0.02) and PEmax (p < 0.05) with a mean increase of 15% for PImax and 12.3% for PEmax. The mean difference in PImax (Delta PImax) and PEmax (Delta PEmax) between the digoxin and placebo groups was 1.01 (95% CI 0.28 to 2.2) and 1.05 (95% CI 0.04 to 2.4), respec tively. Estimates of postoperative pain did not differ between the two grou ps. Spirometric indices showed a similar restrictive defect postoperatively in both groups but did not change after digoxin or placebo. Conclusion-Digoxin improves the impaired global strength of the inspiratory and expiratory muscles after cholecystectomy and this may be clinically re levant. Muscle contractility could play a part in this impairment.