A force meter to assess lower limb motor function after epidural analgesia.

Background and Objectives. Current methods of assessing lower limb motor function using low-dose epidural analgesia are either too insensitive (Bromage scale) or too cumbersome for use during labor. Accordingly, we have designed a force meter that quantitatively measures isometric muscle power of the lower limbs during peak voluntary exertion. Methods. The force meter was tested for linearity using calibrated reference weights. Measurements were made on two occasions (separated by an interval of approximately 5 years), and differences in response were assessed by regression analysis. Departure from linearity was examined by a lack of fit test. Results. There was no significant nonlinearity in response over the range 0-15 kg, nor was there any significant difference in slope between the two functional modes of this device. The device overread slightly at the higher weights. Conclusions. The force meter described was found to be sufficiently accurate and suitable for the quantitative assessment of lower limb motor function after epidural analgesia during labor.