Epidural anesthesia describes the injection of local anesthetic into the epidural space with the result of a complete blockade or reduction in nociceptive input (pain signaling from injured tissue up the spinal cord to the brain) at the spinal cord level resulting in anesthesia or analgesia.
Epidural analgesia using an epidural catheter has been shown to provide excellent pain reduction for an extended time. For a more detailed description of the beneficial effects of epidural analgesia, please read the module ‘Epidural Anesthesia: Effects on Analgesia and other Clinical Outcomes’.
Epidural analgesia using local anesthetic causes sympatholysis via blockade of the sympathetic chain. This mechanism is responsible for some of the benefits as well as of the side effects associated with epidural analgesia.
Serious complications
Serious complications associated with epidural analgesia are fortunately rare, but need to be considered when discussing pain management options. They include (with reported incidences):
|
Dural puncture |
0.32–1.23 % |
|
Neurological damage (usually transient) |
0.016–0.56% |
|
Epidural hematoma |
0.0004–0.03% |
|
Epidural abscess |
0.01–0.05 % |
Other Complications
More commonly seen complications include:
Failure to Provide Good Analgesia
The reported failure rate is actually fairly high: 20-40%. This is most of the time attributable to the epidural infusion not being able to cover the surgical area completely. It can commonly be addressed by adjusting the epidural infusion rate or modality of infusion (such as a change to Programmed Intermittent Bolus Administration). Technical failures are actually a lot less common: a systematic review reported an occurrence of 6.1%.
Catheter Migration
The reported incidence is low, but the risk for catheter migration (the catheter coming out) increases with the time the catheter is being used.
Side Effects
Hypotension
Sympatholysis via blockade of the sympathetic chain can contribute to hypotension, especially in hypovolemic patients, a very common condition in the first days after surgery. Addition of an opioid to the local anesthetic reduces the incidence of hypotension by about 50%, but 10-20% of patients with epidural analgesia are still experiencing hypotension. This results very frequently in a down-titration of the epidural infusion that can limit is analgesic effectiveness. Fluid replacement is, in general, the most effective strategy to address the hypotension unmasked by the epidural infusion. However, frequently the epidural rate needs to be reduced to avoid low blood pressure or orthostasis.
While reducing the concentration of the local anesthetic could be helpful addressing the hypotension, most patients at UCSF are already treated with the lowest ropivacaine concentration available for epidural infusion.
Urinary Retention
Less likely in thoracic epidural infusions and more common in male patients with other risk factors for urinary retention such as benign prostatic hyperplasia.
Pruritus
This is due to the opioid frequently being co-administered with the local anesthetic. Does not respond well to anti-histamines, but reported to respond to ondansetron. More effective are nalbuphine or removal of the opioid from the epidural infusion.
Nausea – Altered Mental Status
May be due to the opioid being co-administered with the local anesthetic. Removal of opioid component and use of local anesthetic only should be considered.
Motor Blockade
Lumbar epidural infusions can result in leg weakness and increase fall risk. Reducing the rate or the local anesthetic concentration can reduce the risk for this complication.
Popping DM, Elia N, Van Aken HK, Marret E, Schug SA, Kranke P, Wenk M, Tramer MR. Impact of epidural analgesia on mortality and morbidity after surgery: systematic review and meta-analysis of randomized controlled trials. Annals of Surgery 2014; 259(6): 1056-1067.
Susan M Nimmo. Benefit and outcome after epidural analgesia, Continuing Education in Anaesthesia Critical Care & Pain, Volume 4, Issue 2, April 2004, Pages 44–47