Local anaesthetics can compromise recovery in a number of ways, as a direct result of their actions, or because of potential side effects:

• Local anaesthetic toxicity may cause cardiac arrhythmias or hypotension
• High spinal/epidural anaesthesia may result in hypotension or respiratory difficulty
• Interscalene nerve block may cause respiratory problems by anaesthesia of the phrenic nerve, especially if there is pre-existing diaphragmatic paralysis on the contralateral side