Regional Anesthesia: Spinal and Epidural Blockade for Surgical Procedures
Spinal and epidural anesthesia are best reserved for operations below the umbilicus. Needle placement is most commonly at the L3/4 and L4/5 interspaces. These include gynecologic and obstetric surgeries, hernia repairs, hip surgery, lower limb surgeries, urologic operations, and operations on the perineum or genitalia.
Spinal and epidural anesthesia may be preferable in patients with respiratory disease, cardiac disease, or who are at increased risk for post-operative delirium. Spinal anesthesia provides more rapid onset of conditions required for surgery in healthy patients compared with epidurals. In older or sicker patients, or more complicated surgeries, the slower onset of epidural blockade may be preferred over spinal anesthesia since it is associated with less hypotension and reflex tachycardia.
Epidurals offer the advantage that placement of the epidural catheter allows for continued maintenance of anesthesia for prolonged periods of time whereas a single spinal injection provides time-limited anesthesia. Epidural catheters are commonly used for labor and delivery analgesia and management of postoperative analgesia.
With a spinal anesthetic, local anesthetics are injected directly into the intrathecal space. With an epidural, a catheter is left in the epidural space which allows for intermittent injection of local anesthetics. Commonly used local anesthetics include lidocaine and bupivacaine. Opioids such as morphine or fentanyl can also be added to the local anesthetics as an adjunct to augment the block.
Contraindications for Central Neuraxial Blockade:
Absolute
- Lack of skilled personnel or proper equipment, including resuscitative drugs and equipment
- Severe hypovolemia
- Infection at insertion site
- Coagulopathy or bleeding diathesis
- Septic shock
- Fixed cardiac output lesions (ex: aortic or mitral stenosis)
- Increased intracranial pressure
Relative
- Pre-existing neurological deficits (ex: MS)
- Severe spinal deformity or prior surgery at site of injection (may make insertion more challenging and block may be unpredictable)
- Prolonged surgery
- Major blood loss
- Maneuvers that may compromise respiration
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