====== Neuraxial anesthesia ======


Neuraxial [[Anesthesia]] is a type of [[regional anesthesia]] where drugs are administered into the central nervous system spaces around the spinal cord to block nerve signals. It includes [[spinal anesthesia]], [[epidural anesthesia]], and combined spinal-epidural anesthesia. This technique is widely used for surgeries, childbirth, and acute pain management.

===== Types of Neuraxial Anesthesia =====

Spinal Anesthesia (Subarachnoid Block):

Location: Injection into the cerebrospinal fluid (CSF) in the subarachnoid space (below the second lumbar vertebra in adults).
Uses: Common in lower abdominal, pelvic, or lower limb surgeries.
Onset: Rapid, typically within minutes.
Duration: Shorter, depending on the drug used (e.g., 2-4 hours).
Technique: Single injection using a fine needle.
Drugs Used:
Local anesthetics: Bupivacaine, Lidocaine.
Adjuvants: Opioids (e.g., fentanyl, morphine), Clonidine.
Epidural Anesthesia:

Location: Injection or infusion into the epidural space, outside the dura mater.
Uses: Labor pain, thoracic surgeries, or postoperative pain management.
Onset: Slower compared to spinal anesthesia (10-20 minutes).
Duration: Longer with continuous infusion via a catheter.
Technique: Placement of a catheter allows for intermittent or continuous drug administration.
Drugs Used:
Local anesthetics: Ropivacaine, Bupivacaine.
Opioids: Fentanyl, Sufentanil.
Combined Spinal-Epidural (CSE):

Location: Combines single-shot spinal with the continuous infusion capabilities of an epidural.
Uses: Provides rapid onset and prolonged effect; useful in labor or complex surgeries.
Advantages: Combines the benefits of both techniques.
Mechanism of Action
Local Anesthetics: Block sodium channels, inhibiting nerve signal transmission.
Opioids: Act on opioid receptors in the spinal cord to reduce pain perception.
Adjuvants: Enhance analgesic effects or prolong the duration.
Indications
Surgical Anesthesia: Lower abdominal, pelvic, hip, or lower limb surgeries.
Obstetric Anesthesia: Labor pain relief (epidural) or cesarean section (spinal or CSE).
Postoperative Pain Management: Especially after thoracic or abdominal surgeries.
Chronic Pain Relief: Epidural for conditions like radiculopathy.
Advantages
Localized Effect: Reduces systemic drug exposure and side effects.
Improved Recovery: Reduces reliance on systemic opioids postoperatively.
Patient Consciousness: Maintains awareness during surgery when appropriate.
Versatility: Can be tailored to the duration and intensity of procedures.
Complications
Common:
Hypotension due to sympathetic blockade.
Post-dural puncture headache (PDPH) after spinal anesthesia.
Serious:
Infection (e.g., meningitis, epidural abscess).
Bleeding (epidural hematoma).
Neurological injury.
Local anesthetic systemic toxicity (LAST).
Maternal Considerations:
Epidural prolonging the second stage of labor.
Fetal bradycardia in rare cases.
Contraindications
Absolute:
Patient refusal.
Infection at the injection site.
Coagulopathy or anticoagulant therapy.
Severe hypovolemia.
Allergy to local anesthetics.
Relative:
Pre-existing neurological conditions.
Spine deformities.
Procedure Overview
Pre-procedure:
Informed consent.
Evaluation of contraindications (e.g., bleeding disorders).
Positioning:
Patient in a sitting or lateral decubitus position.
Technique:
Identify the desired level of injection (usually L3-L4 for spinal, L2-L5 for epidural).
Use sterile technique for needle placement and drug administration.
Monitoring:
Continuous assessment of blood pressure, heart rate, and oxygen levels.

===== Neuraxial drug delivery =====
[[Neuraxial drug delivery]]