Age-related decrease in toe-thumb temperature difference with lumbar epidural anaesthesia.

With lumbar epidural anaesthesia, big toe skin temperature increases and is associated with a compensatory decrease of thumb temperature. The purpose of the present study was to examine whether thumb-big toe temperature differences were affected by age. Following the attachment of temperature probes at the digital pad of the right big toe and the right thumb, lumbar epidural anaesthesia at L2/3 was performed in 54 patients with 10 ml lidocaine 1.5%. Big toe and thumb skin temperatures were measured continuously and recorded every minute. Fifteen minutes after epidural injection, the toe temperature increased 6.3 +/- 2.1 degrees C (delta F) from the control value, 29.4 +/- 2.2 degrees C, and the thumb temperature decreased -1.5 +/- 1.0 degrees C (delta H) from the control value, 31.6 +/- 2.8 degrees C. Regression coefficient between delta T15 (toe-thumb skin temperature 15 min after epidural injection) and age was: Y = -0.7X + 8.95 (r = 0.35, P < 0.01; Y = delta T15, X = age). The ratio of delta H to delta F and age was expressed as: Y = 0.51X - 46.57 (r = 0.41, P < 0.01: Y = delta H/delta F, X = age). It is concluded that, in lumbar epidural anaesthesia, the decrease of the thumb skin temperature is reduced with aging.