Spinal Blocks

What could possibly contraindicate a spinal block?

Hypovolemia

Infections

Deformities

Abnormal coagulation states

Where is the local anesthetic injected in a spinal block?

Lumbar subarachnoid space

What are the landmarks for a spinal and what do they identify?

Spinous processes - midline

Iliac crests - 4th lumbar vertebrae

What are the two patient positions?

Lateral decubitus

Sitting

Describe the procedure of a spinal:

The skin is prepped with an antiseptic and thoroughly dried. A skin wheal is raised using a local anesthetic. A 22 or 25 gauge needle is inserted parallel to the spinous processes. The needle is directed towards the patients head (cephalad) until lodged in the supraspinous ligament. Further advancement pops the needle through the dura mater. After feeling the popping one verifies subarachnoid placement of the needle by looking for CSF in the hub of the needle and injects the local anesthetic.

What is the advantage of using a 25 gauge needle?

Incidence of post-spinal headache is reduced.

22 Gauge needle?

An introducer is not needed with this larger needle.

Rank the local anesthetics in order of length of duration:

Tetracaine and bupivacaine > lidocaine > procaine

How much longer can a vasoconstrictor prolong a spinal block?

50%

What does a spinal block interrupt?

Sensory, motor and sympathetic systems.

What does sympathetic block often cause?

Decreased venous return resulting in hypotension. Bradycardia may contribute to further reductions in cardiac output.

What are characteristics of a post-spinal headache?

Frontal or occipital pain

Made worse by sitting

Improved in supine position

Sometimes accompanied by diplopia, tinnitus, and decreased hearing

What causes post-spinal headached and how do you treat it?

Caused by decreased CSF pressure due to leakage and treated by:

1) Bedrest, analgesics and hydration

2) Caffeine sodium benzoate

3) "Blood patch" (10-20 ml of patient's blood)

What are some other complications of a spinal block?

1) Backache

2) Nausea and vomitting

3) Hypoventilation

4) Urinary retention