A method for the measurement of tremor, and a comparison of the effects of tocolytic beta-mimetics

A method permitting measurement of finger tremor as a displacement-time curve is described, using a test system with simple amplitude calibration. The coordinates of the inversion points of the displacement-time curves were transferred through graphical input equipment to punched tape. By means of a computer program, periods and amplitudes of tremor oscillations were calculated and classified. The event frequency for each class of periods and amplitudes was determined. The actions of fenoterol-hydrobromide, ritodrin-HCl and placebo given to 10 healthy subjects by intravenous infusion in a double-blind crossover study were tested by this method. At therapeutic doses both substances raised the mean tremor amplitude to about three times the control level. At the same time, the mean period within each class of amplitudes shortened by 10--20 ms, whereas the mean periods calculated from all oscillations together did not change significantly. After the end of fenoterol-hydrobromide infusion, tremor amplitudes decreased significantly faster than those following ritodrin-HCl infusion.