To give valid consent, a patient must be informed of the potential risks of regional anesthesia. That includes information that a reasonable patient would expect to receive from the anesthesia team.
Serious risks are rare and benefits (improved pain control / rehabilitation / recovery, reduced opioid use and its side effects, avoidance of GA etc.) far outweigh any risk.
Incidence of peripheral nerve injury - long term injury 2-4 per 10,000 nerve blocks; short term (resolved within 3 months) neurological symptoms 0.5-1%. Note that the use of ultrasound guidance has NOT been shown to reduce incidence of long term injury. Also, it is possible that more proximal nerve blocks, e.g. interscalene block, carry a higher risk of nerve injury compared to more distal ones. Furthermore, patient factors (pre-existing peripheral neuropathy) and surgical factors (e.g. tourniquet neuropahty, mechanical injury) can also be contributory.
Incidence of neuraxial complications (e.g. hematoma, infection, direct cord injury) - extremely rare but often results in devastating permanent injury. Incidence varies widely dependent on modality (epidural > spinal), patient factors (increased risk with age, female, concurrent spinal stenosis / neurologic diseases, immune / coagulation status). Risk of paraplegia or death from neuraxial techniques 0.7-1.8 per 100,000. Risk of permanent injury (but not death or paraplegia)1:5800 to 1:12,200.
Home Base Zone (green area in the scale) - These risks often represent activities that most people feel comfortable with and, although we're aware they come with a remote chance of serious accidents, most of us don't alter our lifestyles to avoid them. Dr. Paling, John
Other potential complications that are worth mentioning: 1. Block failure (reassure patients block will be checked) 2. LAST (mitigate by careful technique and proper dosing) 3. Pneumothorax (e.g. supraclavicular, paravertebral blocks) 4. Known transient side effects of certain blocks (e.g. phrenic nerve palsy, Horner's)
For out patients, advise about care and protection of blocked limb: Minful about diminished sensation, proprioception, and weakness of the affected limb. Inform the patient to guard the limb and not to attempt any tasks with it until resolution of block.
A collection of articles on regional anesthesia complications can be found here.
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