Effects of digoxin on diaphragmatic contractility in the piglet

Minute ventilation, arterial blood gases and pH, cardiac output, and transdiaphragmatic force generation were measured in eight anesthetized, tracheostomized piglets before and after administration of 40 micrograms/kg body wt of digoxin. No changes were noted in cardiac output, heart rate, tidal vol, respiratory rate, or minute ventilation. Blood pressure decreased from baseline to 60 min postinfusion. No change was noted in the force frequency curves at 30 and 60 min postinfusion. Serum digoxin levels averaged 10.4 ng/mL at 30 min and 5.6 ng/mL at 60 min. In seven control animals, no changes were noted in any ventilatory or hemodynamic parameter from baseline to 60 min. In contrast to the reported effects of digoxin on the diaphragm of adult humans and animals, digoxin did not augment diaphragmatic contractility in normal infant swine.