Influence of age on spinal anaesthesia with isobaric 0.5% bupivacaine

Possible correlations between age and certain characteristics of spinal blockade with plain bupivacaine were investigated in 124 patients, ages ranging from 15 to 92 yr. Three millilitre of 0.5% solution (sp. gr. 1.000 at 37 degrees C) was injected at the L3-L4 interspace. There were great individual variations in all age groups, but the maximum spread of analgesia increased with age, although the correlation was poor (P less than 0.05). The spread of analgesia to L2 and L3 segments in the oldest patients (greater than or equal to 70 yr) was about twice as fast as that in the youngest (less than 30 yr). Complete motor blockade of the lower extremities developed most rapidly in the oldest patients (greater than or equal to 80 yr; mean 11 min), while in patients younger than 50 yr the mean time to complete motor block was approximately doubled. The mean sensory recovery of the two uppermost segments and the mean sensory recovery of the S1 segment did not correlate significantly with age. The decrease of systolic arterial pressure was correlated with the height of the sensory block only in the oldest (greater than or equal to 80 yr) patients. Post-spinal headache was encountered in two patients (1.6%).