Regression pattern of amplitude of electrocardiographic waves during intravenous infusion in intact, buffer nerve denervated and spinal dogs.

Electrocardiographic (ECG) amplitude changes during clinically feasible rate of infusion of normal saline (NS), Ringer-Locke (RL) solution and tender coconut water (TCW) upto a dose of 100 ml/kg in paraldehyde (PLD) and chloralose and urethane (C&U) anaesthetised dogs were studied. The infusion caused a net decrease in P and QRS amplitudes but had varied effect on T wave amplitude in intact PLD and C&U anaesthetised dogs. Infusion of RL in vagotomised and/or carotid sinus (CS) denervated dogs and in spinal dogs indicated that these neural pathways had a significant effect on basal amplitude of ECG waves but their influence on infusion induced ECG changes was only marginal; in this the vagi seem to have a greater influence than the other pathways. The T wave changes during infusion were independent of simultaneous P and QRS changes and appeared to depend on the ionic composition of the infusion fluid. TCW infusion was very well tolerated, particularly by the C&U anaesthetised dogs. It would seem that the evaluation of ECG from patients on parenteral fluid be done in the context of the present observation that infusion per se decreases the amplitude of ECG.