Background: The relative effects of the mass, volume and concentration of local anaesthetic solution used for epidural anaesthesia and analgesia are still under debate. Clinical studies have shown discrepancies, probably because of limited consideration of total dose.
Methods: This prospective, randomized and blinded study evaluated the spread, the quality of post-operative analgesia and the incidence of side-effects of continuous thoracic epidural levobupivacaine 15 mg/h in three different concentrations: 1.5 mg/ml, 10 ml/h (n = 26), 5 mg/ml, 3 ml/h (n = 33) or 7.5 mg/ml, 2 ml/h (n = 31). The following variables were registered within 48 h: sensory block, pain scores, rescue morphine consumption, motor blockade, haemodynamics, sedation, nausea and vomiting, and patient satisfaction.
Results: The three groups were similar with regard to demographics, quality of analgesia, morphine consumption, and satisfaction rate. The upper level of sensory block was two segments higher in the 1.5 mg/ml group. Motor blockade in the lower limbs was low in the three groups. Haemodynamic profile was more stable in the higher concentration groups compared with the 1.5 mg/ml patient group (P < 0.001). Nausea was more frequent in the 1.5 mg/ml group (P = 0.02).
Conclusion: The same dose of levobupivacaine provides an equal quality of analgesia in low or high volume continuous thoracic epidural infusion with reduced haemodynamic instability and nausea in the low volume/high concentration groups.