Quality of epidural blockade. II. Influence of physico-chemical factors; hyaluronidase and potassium.

A trial was made of hyaluronidase and potassium chloride as adjuvants for epidural analgesia in 137 patients. Lignocaine hydrochloride in 2 per cent concentration with adrenaline 1/200,000 was used as the control solution in 61 cases; hyaluronidase, 5 USP units/ml, was added in 26 cases, and 1 per cent potassium chloride was added in 50 cases. Hyaluronidase tended to impair the quality of sensory blockade rather than to enhance it, whereas 1 per cent potassium chloride gave rise to a shortened latency of spread and a more intense quality of sensory block, especially in the sacral segments. It is concluded that hyaluronidase has no place in epidural analgesia. Potassium chloride should be used with great caution because it produces undesirable effects if introduced into the subarachnoid space.