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Questions and Answers
What structures does the needle pierce before reaching the cerebrospinal fluid (CSF)?
What structures does the needle pierce before reaching the cerebrospinal fluid (CSF)?
- Subcutaneous fat, Supraspinous ligament, and Ligamentum flavum
- Subarachnoid space, Dura, and Spinal cord
- Skin, Dura, and Epidural space
- Interspinous ligament, Ligamentum flavum, and Epidural space (correct)
What is the purpose of injecting local anesthetic into the subarachnoid space below the level of L2?
What is the purpose of injecting local anesthetic into the subarachnoid space below the level of L2?
- To achieve anesthesia of the lower half of the body below the umbilicus (correct)
- To block sensory nerves
- To avoid peripheral vasodilatation
- To stimulate motor nerves
What position is commonly used for administering a spinal anesthetic?
What position is commonly used for administering a spinal anesthetic?
- Sitting position (correct)
- Supine position
- Lateral position
- Prone position
Which type of needle is preferred to avoid excessive cerebrospinal fluid (CSF) loss?
Which type of needle is preferred to avoid excessive cerebrospinal fluid (CSF) loss?
What volume of heavy bupivacaine 0.5% is typically injected into the subarachnoid space?
What volume of heavy bupivacaine 0.5% is typically injected into the subarachnoid space?
What happens when a localized sympathetic block occurs during spinal anesthesia?
What happens when a localized sympathetic block occurs during spinal anesthesia?
What anatomical structure marks the endpoint during a spinal anesthetic injection?
What anatomical structure marks the endpoint during a spinal anesthetic injection?
What is the specific gravity of hyperbaric bupivacaine compared to cerebrospinal fluid (CSF)?
What is the specific gravity of hyperbaric bupivacaine compared to cerebrospinal fluid (CSF)?
What happens if the spinal needle is inserted above L2?
What happens if the spinal needle is inserted above L2?
Why is it important to identify the subarachnoid space during a spinal anesthetic injection?
Why is it important to identify the subarachnoid space during a spinal anesthetic injection?
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Study Notes
Epidural Anesthesia
- Close monitoring of heart rate, blood pressure, and respiration is crucial.
- Technique, site, and speed of injection are important factors.
- Local anesthetic volume, concentration, specific gravity, and additives must be considered.
- Patient position after injection affects the outcome.
Complications
- Early complications: bradycardia, hypotension, respiratory embarrassment, nausea, and vomiting.
- Delayed complications: post-dural puncture headache, back pain, urinary retention, and diplopia.
- Rare complications: meningitis, meningism, and neurological deficit.
Procedure
- Epidural anesthesia can be done at all levels of the vertebral column (cervical, thoracic, lumbar, and sacral).
- The epidural space is identified by loss of resistance to injection of saline or air after piercing the ligamentum flavum.
- A large dose of local anesthetic (about 20 ml lignocaine or bupivacaine) is injected into the epidural space.
- An epidural catheter can be inserted for postoperative analgesia.
Characteristics
- Slow onset: about 20 minutes, and less intensity of sensory and motor block than spinal.
- Disadvantages: time-consuming, and higher rate of failure than spinal.
Comparison with Spinal Anesthesia
- Puncture level: all vertebral column (epidural) vs. below L2 (spinal).
- Injection site: epidural space (epidural) vs. subarachnoid space (spinal).
- Needle shape: larger gauge, curved tip (epidural) vs. small gauge, pointed tip (spinal).
Contraindications
- Patient refusal, uncooperative patients, coagulation disorders, and patients on anticoagulant drugs.
- Infection, increased intracranial tension, neurological disorders, low fixed cardiac output, and hypovolemia.
- Anatomical deformities, previous back surgery, and inadequate resuscitative drugs and equipment.
Anatomy
- Spinal nerves: 31 pairs, and spinal vertebrae: 33.
- Cauda equina: formed of lumbar, sacral, and coccygeal nerves.
- Subarachnoid space: lies between Pia and Arachnoid mater, contains spinal cord, CSF, nerves, and blood vessels.
- CSF: about 150 ml, 30 ml of which in the spinal subarachnoid space.
Spinal Anesthesia
- Structures pierced by the needle: skin, subcutaneous fat, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura, and subarachnoid space.
- Local anesthetic blocks conduction of impulses along the spinal nerve roots leading to anesthesia of the lower half of the body below the umbilicus.
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