Extradurals and shivering: effects of cold and warm extradural saline injections in volunteers.

We tested the hypothesis that cooling the extradural space may provoke shivering, by giving three 80-ml extradural injections of warm (39.8 +/- 1.2 degrees C) or cold (17 +/- 2.2 degrees C) saline to four healthy volunteers, whilst recording central temperature and electromyographic activity from four muscles. The first injection (always cold) did not induce shivering in any of the subjects. The second and third injections, randomly cold or warm, were given after induction of shivering with cold blankets, but had no detectable effects on the intensity of shivering. This suggests that shivering in extradural anaesthesia does not result solely from cooling of the extradural space.