Anaesthetists Handbook - MEDICAL EDUCATION at University ...

Pain management and postoperative careKetamineIt is an antagonist at NMDA receptors; these receptors have asignificant role in chronic pain.1. Ketamine is not an ideal first line drug in postoperative painmanagement in patients with chronic pain because of thepsychomimetic adverse effects.2. There is no evidence that pre-emptive use of this medicine canprevent development of chronic pain.3. In occasional opioid tolerant cases, low-dose ketamine (10-25mg bolus or 0.50-1 mg kg -1 hour -1 infusion) has been usedsuccessfully.Regional anaesthesiaSatisfactory postoperative pain relief in chronic pain patients isdifficult exclusively with pharmacological means, because of neuronalchanges resulting in hyperalgesia.1. Single shot central neuraxial, paravertebral, peripheral nerveblocks, local infiltration and joint injections provide good painrelief in the immediate postoperative period. Ensure enoughanalgesics and normal medications are prescribed under‘regular medications’ – otherwise patient will wake-up in themiddle of the night with agonizing pain.2. Continuous catheter infusions are especially helpful. Epiduralmixtures of local anaesthetics and opioids provide superiorpostoperative pain control in chronic opioid dependent patients.3. Although regional block can provide pain relief for acute surgicalpain it is important to continue the background analgesicmedications and adjuncts for managing underlying chronic painand to prevent withdrawal syndrome.Ineffective analgesia can lead to anxiety, distress, drug seekingbehaviour and demands, as well as pain. It delays recovery anddischarge.116 Anaesthetists Handbook January 2010