Analysis was based on treatment completers only, except for measurement of catheter dislodgement, leaving 21 in each group for analysis. Primary health outcomes were:
(1) the rate of catheter dislodgement,
(2) other mild side effects (including itching, nausea, respiratory depression and transient hypotension),
(3) the time taken for the patient to accept liquids and
(4) the time taken for the patient to accept solids,
(5) the time to ambulation,
(6) the length of stay, and
(7) pain recorded by a visual analogue scale on postoperative days 1, 2 and 3.
Groups were shown comparable in terms of age, number of levels fused, the use of instrumentation, estimated blood loss and intra-operative complications.