The additive analgesia of adrenaline in epidural blockade

The landmark paper discussed in this chapter is ‘Adrenaline markedly improves thoracic epidural analgesia produced by a low-dose infusion of bupivacaine, fentanyl and adrenaline after major surgery’, published by Niemi and Breivik in 1998. The analgesic potential of neuraxial blockade has long been recognized. The extensive opioid receptor expression in areas germane to pain pathways gave credence to the effective clinical application of lower doses of neuraxial opioids compared with systemic administration. Preclinical data also proposed a potential spinal action of α‎2 agonists in achieving analgesia by a number of mechanisms, including a direct antinociceptive action and by reducing elution of other epidural drugs from the spinal effector site. Early clinical data failed to show a clear benefit from the addition of adrenaline to epidural infusions. Niemi and Breivik’s experiment addressed the methodological flaws of previous studies by using combinations of relatively sub-analgesic doses of each of the combined elements.