**4.5 Adjuvants in regional anaesthesia**

The adjuvants to neuroaxial anaesthesia and peripheral nerve blocks are used in clinical practice: opioids, vasoconstrictors, clonidine, N-methyl-D-aspartate (NMDA) antagonists, γ-aminobutyric acid (GABA) agonists, glucocorticoids, nonsteroidal anti-inflammatory drugs and neostigmine. Analgesia produced by neuraxial opioids alone, or as adjuvants to local anaesthetics, has been demonstrated for acute post-operative pain, obstetric, paediatric and cancer pain [20]*.* Besides morphine, a number of different opioides and other adjuvants have been introduced to improve the efficacy of neuraxial/regional analgesia, including NMDA antagonists (ketamine, magnesium), GABA agonists (midazolam) and adrenergic agonists (clonidine, adrenaline), COX-inhibitors (ketorolac), acetyl-choline-esterase inhibitor (neostigmine), etc*.* Any drug given intrathecally rapidly redistributes within the CSF; opioid is detectable in the cisterna magna after lumbar intrathecal administration within 30 min, even with lipophilic drugs like sufentanil.

Glucocorticoids are part of induction of anaesthesia in different clinical protocols achieving much improved analgesia and minimised inflammation with reduced opioid requirements and less adverse events after surgery. Dexamethasone is a long-lasting corticosteroid with effectiveness of 36–54 h [17]. Dexamethasone prolongs sensor and motor blockade with significantly reduced post-operative analgesic requirements, which means it can inhibit phospholipase-A2 and cyclooxygenase-2 expression during inflammation decreasing prostaglandin synthesis [18]. Dexamethasone administered intrathecally affects nuclear transcription in adrenergic receptors [19].

In the study by Bani-hashem et al., intrathecal addition of dexamethasone to bupivacaine for elective orthopaedic surgery on lower limbs significantly prolongs duration of sensory block and decreases opioid requirements in post-operative management. Administration of dexamethasone has the potential to inhibit a patient's endogenous secretion of cortisol. Dexamethasone inhibits corticosterone binding to type II of adrenergic receptors in the pituitary gland passing through the cerebrospinal fluid bound to proteins. Irrelevant of the concentration, dexamethasone has a similar effect on type II of adrenergic receptors. It is possible to resorbs somewhere in the brain without effect on other types of receptors along the HPA axis not depending on the concentration [20]. Single shot of intrathecally administered dexamethasone with levobupivacaine received for surgical treatment of proximal femoral fractures reduces the stress response by decreasing plasma cortisol concentrations with longer lasting analgesic effect with better rehabilitation possibilities [21].

Based on a 2004 Cochrane systematic review of anaesthesia for hip fracture surgery, regional anaesthesia may reduce the incidence of post-operative confusion, the Scottish Intercollegiate Guidelines Network has produced the only recommendation concerning choice of anaesthetic technique, namely that 'spinal, /epidural anaesthesia should be considered for all patients undergoing hip fracture repair, unless contraindicated'. Until such time as evidence is published that confirms regional anaesthesia is superior to general anaesthesia, the Working Party endorses this recommendation. This endorsement is supported by a recent meta-analysis suggesting that regional anaesthesia is the technique of choice (although) the limited evidence available does not permit a definitive conclusion to be drawn with regard to mortality or other outcomes [22].
