Neuraxial: Procedures

Discuss pros and cons of the following:

Single shot spinal

Epidural

Combined epidural and spinal

Continuous spinal

Name some examples of procedures that you may use an epidural or spinal in? Will you need additional GA?

Which surgeries would neuaxial placement be needed in the upper thoracic area?

Thorcotomy

Pectus repair

Thoracic aortic aneurysm repair

Which surgeries would neuaxial placement be needed in the mid thoracic area?

Upper abd surgery like:

Esophagectomy

Gastrectomy

Pancreatectomy

Hepatic resection

Which surgeries would neuaxial placement be needed in the lower thoracic area?

Lower abd surgery:

AAA repair

Colectomy

Abd perineal resection

WHat are absolute contraindications to neuraxial

Infection at site

Pt refusal

Coagulopathy

Severe hypovolemia

Increased ICP

Severe aortic stenosis

Severe mitral stenosis

What aresome relative contraindications to neuraxal

Sepsis

Uncooperative pt

Preexisting neuro deficit

Demyelating lesions

Stenotic valvular heart lesions

Left ventricular outflow obstruction (hypertrophic cardiomyopathy)

Can you ever use a neuraxial technique in a pt with thrombocytopenia

• Yes, The etiology of thrombocytopenia, the pt’s bleeding history, and a trend in platelet count must be taken into account when determining the safety of epidural in thrombocytopenic patients.  Conditions such as ITP and gestational thrombocytopenia are assoc. with functioning platelets despite a low platelet count.

MOA of a spinal

• LA injected into the CSF spreads to the nerves of the cauda equina and laterally to the nerve roots

Explain the difference between these needle types:

Quincke

Sprotte

Whitacre

Greene

Pitkin

Tuohy

Starting at the skin, name the layers that are passed during a midline spinal approach

How does the paramedian approach differ from the midline approach?

Paramedian enters 1.5 cm laterally to the inferior border of the spinal process

WHat factors affect spread of a spinal

AKA position block- dependent on baricity and dose

How do you determine baricity?

Density of the LA/ density of the CSF at 37C

How can you create a hypobaric LA? Where will this posiion?

• LA mixed with sterile H2O or warmed a little

• Flows up in the CSF column

How can you create a isobaric LA? Where will this posiion?

• LA approx. = to CSF density

• Stays at about the same spot in the CSF column

How can you create a hyperbaric LA? Where will this posiion?

• LA mixed with dextrose

• Flows to most dependent part of the CSF column due to gravity

  • Baricity and Spinal Contour

What is the high point of the spine in the supine position? Low point?

High point- L3-4

Low Point- T5-6

WHat 4 factors effect the uptake of LAs from the subarachnoid space to the neuronal tissue

• 1) concentration of local anesthetic in CSF

• 2) surface area of nerve tissue exposed to CSF

• 3) lipid content of nerve tissue

• 4) blood flow to nerve tissue.

What are the zones of a differential blockade?

ANS>sensory> motor

Motor block- hardest to achieve

Sensory Block- 2 levels above motor

Sympathetic Block- 2 levels above sensory

How should you treat HOTN caused by sympathetic blockade?

Prompt IV fluids and phenylephrine

What is the general progression of block onset? How does function return?

At what level would sympathetic block result in bradycardia?

T4- location of cardioaccelerator fibers

What level would a block have to be located to not interferewith the SNS?

T12

Who is more likely to get a post dural puncture headache?

Young, females, low BMI, h/o headaches

Also correlateswith needle size and type

What is the most common complication of spinal

Backache

MOA of epidural

• Medication retained in the fatty tissue of the epidural space

• Some absorbed into the circulatory system

• Remainder will enter the spinal nerves and nerve roots

• Spread occurs through the dural cuff to the CSF via arachnoid granulations

Name examples of each needle type:

Pencil

Cutting

Epidural

Pencil point= Whitacre/Sprotte

Cutting=Greene, Quincke

Epidural=Tuohy, Hustead

Which layer may be skipped with the paramedian approach?

Supraspinous ligament (and maybe the interspinous ligament)

What determines the level of a block with an epidural?

AKA volume block (more controllable compared to spinal)

• Segmental block- dermatome by dermatome

  • Typically 1-2 cc per dermatome blocked

  • Therefore 10 cc will block ~5-10 dermatomes

What is a typical length to enter the epidural space?

4-6cm

What is a typical test dose? What would be seen in a positive test dose?

3cc 1.5% lido + 1:200,000 epinehrine

Name some early complications of an epidural

• Dural puncture

• Unintentional SAB = ‘Wet Tap’

• LA overdose

• Backache

• Bloody tap= epidural veins

• Intravascular injection

  • LA toxicity

• Catheter complications

  • Kinking, migrating, trapping by ’facet’

• Neurologic injury

Name some late complications of an epidural and how may you treat them

• Post-dural puncture headache

  • Conservative treat

  • Epidural blood patch

• Infection

  • Abx and drainage

• Epidural hematoma

  • True surgical emergency

  • Laminectomy