Control of spinal blockade. A volume expansion technique with hyperbaric cinchocaine

Subarachnoid anaesthesia was performed using 2 ml of hyperbaric cinchocaine diluted with cerebrospinal fluid in 83 patients. When different volumes of the diluted cinchocaine (6 ml or 8 ml) were injected in the same manner into two comparable groups of patients in the height range of 150-180 cm, there was a statistically significant (p less than 0.001) difference in the mean levels of the analgesia obtained. Individual values had a narrow range of spread for a given volume of injectate. There was no significant correlation between maximum analgesic levels and age and height in this group. When the smaller volume of 6 ml was given to 21 patients under 150 cm in height, there was a statistically significant correlation (r = -0.74) between height and levels obtained. It is possible to obtain the required analgesic levels by varying the volume of dilution without altering the drug dosage, but height is an important consideration in patients of less than 150 cm.