Regional analgesia approaches can be used for several reasons. The ability to provide selective analgesia with minimal adverse effects can be beneficial, particularly in older patients, who may have co‐existing conditions (Macintyre and Schug [99], Parizkova and George [137], [138]). A nerve block or a continuous infusion of local anaesthetic can provide pain relief that is superior to the use of opioids alone, and the use of opioids can be minimized in the post‐operative setting, resulting in fewer adverse effects, such as nausea, vomiting, sedation and pruritus (D'Arcy [45]). Pain relief and functionality may also be improved. Ilfeld ([85]) found that, in comparison with systemic opioid analgesia (including PCA), CPNB leads to better pain relief and fewer opioid‐related side‐effects. Humble et al. ([82]) found during their systematic review of perioperative interventions that regional analgesia was beneficial for reducing perioperative pain and subsequent chronic symptoms.

Regional analgesia can be administered as a single‐shot injection where the effects last for several hours after the procedure or as a continuous infusion (CPNB). CPNB can be used in both the inpatient and ambulatory care settings. CPNB analgesia infusion pumps can also be programmed to allow patients the option of bolus dosing in addition to the baseline continuous infusion rate.

In peripheral nerve blocks, the most frequently used drug is a local anaesthetic. Commonly used local anaesthetic agents include bupivacaine, levobupivacaine and ropivacaine. Local anaesthetics bind directly within the intracellular portion of voltage‐gated sodium channels. The degree of block produced by local anaesthetics is dependent on how the nerve has been stimulated and on its resting membrane potential. Local anaesthetics are only able to bind to sodium channels in their charged form and when the sodium channels are open. They cause numbness and loss of sensation and there may also be some loss of muscle function depending on the purpose of the block.

The dose of a local anaesthetic agent will also determine which nerves are blocked. Low concentrations of bupivacaine (e.g. 0.100–0.125%) preferentially block nerve impulses in the smallest‐diameter nerve fibres, which include the pain and temperature sensory fibres. As the larger‐diameter motor fibres are less likely to be blocked with concentrations of 0.100–0.125% bupivacaine, the incidence of motor weakness is reduced and patients are able to mobilize.