Journal: Anaesth Intensive Care Med 8(4):151-154, 2007. 7 References
Reprint: Dept of Anaesthesia, Alexandra Hospital, Redditch, Worcestershire Acute Hospitals NHS Trust, UK (B Fischer, FRCA)
Faculty Disclosure: Abstracted by T. Tilton, who has nothing to disclose.
Complications of regional anesthesia (RA) are generally minor, easily managed, and temporary in nature but can be serious, resulting in permanent damage. Practitioners must differentiate between side effects, which can be anticipated and may be used to patient's advantage, and complications, which are usually unexpected and may cause harm even when promptly recognized and treated. Strategies to minimize the effects of motor, sensory, and proprioceptive blocks include: adequate support for affected limbs; prevention of joint hyperextension or flexion; protective padding of pressure areas (especially heels and elbows); and maintenance of appropriate blood pressure and heart rate. Estimates of the incidence of serious, permanent injury, or fatality consistently range from 0.2-5:10,000 for adult, non-obstetric patients and for children and obstetric patients, <0.1:10,000.
Technique-related complications include failure, total spinal, and equipment factors. One significant risk factor for serious neurological damage is multiple attempts at a regional technique. Generally, 2 to 3 unsuccessful attempts may indicate the need to stop, seek help, or use an alternative technique. Specifically, a failed spinal should not be repeated because neurological damage is more likely, probably due to maldistribution of local anesthetic within the cerebral spinal fluid (CSF) and localized nerve toxicity due to high local anesthetic concentration around a few nerve roots.
Total spinal presents as rapid onset of profound motor blockade and high dermatomal sensory block. If the local anesthetic reaches the cervical spine, weakness of the upper limbs and respiratory embarrassment or even respiratory failure occurs. If local anesthetic reaches the CSF, unconsciousness, respiratory arrest, severe hypotension, and pupillary dilatation ensue. Treatment is supportive until the block regresses, about 2 to 4 hours.
Equipment issues include catheter insertion (penetration of epidural blood vessels or subdural layer of the dural sac into the CSF), insertion of excessive catheter length (may exit the intended space to encircle a nerve root or knot), and design of the spinal needle tip (some pencil-points increase the risk of spinal cord injury but reduce the risk of postdural puncture headache). Current opinion supports the use of short-bevel cutting needles for both peripheral and spinal blocks, which offer the best risk/benefit balance, but for obstetric patients, the pencil-point (especially Whitacre) should be performed at levels no higher than L3-4.
Causes of major neurological complications include technique failure (due to multiple attempts or failed spinal), direct nerve trauma (intraneural injection or needle damage to spinal cord or major peripheral nerve/plexus), infection (viral/bacterial, perineural, or epidural/intrathecal), hematoma (epidural or brachial plexus), drug toxicity (transient neurological symptoms, adhesive arachnoiditis, drug error), and miscellaneous (anterior spinal artery syndrome or spinal cord infarction).
The incidence of epidural abscess formation occurs rarely (1:1000-1:100,000) and is influenced by risk factors such as compromised immunity, spinal column disruption, and pre-existing sources of infection. Most epidural-associated infections are limited to superficial skin or subcutaneous tissue infection along the catheter tract. Any sign of infection or complaints of lumbar spinal pain need to be investigated and treated promptly. It is recommended to review the website of the American Society of Regional Anaesthesia for current information about epidural hematoma and the use of thrombolytics.
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