To study the haemodynamic effects of intrathecal meperidine, administered either alone or mixed with bupivacaine. We studied 42 Chinese patients, aged 59-87 yr, scheduled for transurethral bladder or prostate surgery, randomized into three equals groups, that received either meperidine 0.8 mg.kg-1, meperidine 0.4 mg.kg-1 plus 1.5 ml of 0.5% heavy bupivacaine or 3 ml of heavy bupivacaine 0.5%. Non-invasive systolic (SAP) and mean (MAP) arterial pressures, central venous pressure and cardiac index, stroke index and heart rate (HR) measured by the BoMed NCCOM3-R7S bioimpedance device, were recorded over the first 25 min. Systemic vascular resistance index (SVRI) was derived. Onset of sensory and motor block was also measured. Decreases in MAP of 25% were treated with colloid and metaraminol. The onset of block was slower in the meperidine group (P < 0.05). Decreases in SAP, MAP and SVRI (all; P < 0.001) occurred within five minutes in all three groups. The HR was increased in the bupivacaine group (P = 0.03), but bradycardias treated with atropine occurred in six patients receiving meperidine and four patients receiving the mixture. Six patients receiving meperidine and two patients receiving the mixture required general anaesthesia for inadequate block. The incidence of nausea and vomiting was higher in the patients receiving meperidine (P < 0.05). No other complications were encountered. Intrathecal meperidine used alone or mixed with bupivacaine has no intra-operative advantage over heavy bupivacaine 0.5%. Conway, Critchley, Stuart, Freebairn, , , , , (1996). A comparison of the haemodynamic effects of intrathecal meperidine, meperidine-bupivacaine mixture and hyperbaric bupivacaine.¬†Canadian journal of anaesthesia = Journal canadien d’anesthesie, 1996 Jan;43(1):23-9.¬†https://www.ncbi.nlm.nih.gov/pubmed/8665630