Patients' assessment of sensory levels during epidural analgesia in labour.

Thirty women in established labour and with epidurals in situ were asked to assess the sensory level of the epidural using loss of light touch sensation with their own finger. This dermatomal level was then compared to the sensory level assessed by an anaesthetist using loss of cold sensation with ethyl chloride spray. A total of 88 assessments were made. The mean dermatomal difference was 0.20 and 95% of the differences lay between 3.5 and -3.1 dermatomes. This large variation in dermatomal differences between the two methods of sensory assessment means that patient light touch is not an acceptable method of assessing epidural sensory level when compared to ethyl chloride.