Regional Quiz #7 Flashcards
What is some of the differences between epidural and spinal’s?
- Same as spinal except it allows continuous anesthesia secondary to the placement of a catheter.
- More suitable for procedures of longer duration and for extended use in the post-op period to deliver long-term, titratable anesthesia
- Spinal is one-shot deal; epidural is prolonged
Explain steps for epidural procedure.
- Make skin wheal with lidocaine
- Use Touhy needle
- Go into skin
- Go thru subcut tissue
- Into Supraspinous ligament: once in this ligament, if you let go of needle, it will not move. If just in subcut tissue, it will be floppy.
- Pull stylet out
- Get glass “loss of resistance” syringe, use filter needle to draw up saline to wet the barrel of syringe, easier to slide.
- Place it onto needle with air or saline inside, keep finger on plunger side and advance little by little.
- Once you get to ligamentum flavum (feels like hard rice krispy treats), push a little bit further.
- Once ligamentum flavum transversed, syringe should rapidly expel due to negative pressure inside the epidural space.
- Get epidural catheter and thread it until the 20 cm mark (4 single-line mark)
- Then, apply forward pressure to the catheter while slowly removing needle
- As soon as the tip of the needle is out and catheter at skin level is exposed, grab catheter at this site and anchor in place while the needle is fully removed.
- Pull/retract catheter out until you see the solid black line (12.5 cm), which leaves roughly 10-11 cm catheter at skin.
- If it took 5 cm to reach loss of resistance, subtract it from 10 or 11= 4-6 cm inside the epidural space
If too much air is expelled into epidural space, what can it cause?
Pneumocephalus: can recreate symptoms of PDPH
T or F: Each epidural catheter is graduated at 1 cm increments, for a total of 8.9 to reach the little white piece attached to the hub (8.9 cm of stainless steel).
True
What is the cm amount that 80% of women have loss of resistance with epidural insertion?
Between 4-6 cm
What is the cm length of the first double line on epidural catheter?
10.5 cm
What is the cm length of the solid black line?
12.5 cm
At what cm length does the epidural catheter start exiting the epidural needle?
12.5 cm, at the first solid black line after the double black line
T or F: If your epidural catheter goes into the patient 4 cm, never pull catheter back out when needle is still in place; it will cause potential shearing of catheter.
True
If you are unable to advance catheter how far it needs to go, what should you do?
Take the needle out and then slowly pull catheter out…then start over.
How many cm of catheter should be left into epidural space?
- 4-6 cm max
- Epidural spaces have epidural plexuses, fat, septums that separate rt/lt halves
- The more you thread, the more likelihood of threading into epidural vein or a dural sleeve on one side or the other
What is a test dose for epidural catheter insertion?
- To make sure that epidural catheter is not in subarachnoid space or in epidural vein, take 3 ml of 1.5% lidocaine w/epi (1:100,000 or 1:200,000=5mcg/ml)
- If test dose is injected into spinal space, patient will have response in 3-5 minutes
- If test dose is injected into vein, the 15 mcg of epi will cause transient increase in HR
What should you do if after dosing the epidural and patient has only one side numb?
-untape everything and pull catheter out 1 cm, and dose again
T or F: Single-shot epidurals are usually seen with epidural LA/steroid injections; catheters are not threaded for chronic pain patients.
True
How does LA and other solutions spread through epidural space?
- Horizontally, left and right, into the dural cuffs
- Dural cuffs where it diffuses into CSF and leak into intervertebral foramen and paravertebral spaces (where nerve roots are!)
- Then Longitudinally: primarily cephalad acting on paravertebral nerve trunks, intradural spinal roots, dorsal/ventral spinal roots, dorsal root ganglia, spinal cord, and brain.
Know roots of spinal nerves, dorsal root, ganglia, spinal nerve, dorsal ramus, ventral ramus.
These are the sites where epidural LA will take effect
Know roots of spinal nerves, dorsal root, ganglia, spinal nerve, dorsal ramus, ventral ramus.
These are the sites where epidural LA will take effect
T or F: Epidural medication diffusion is dependent on large volumes of LA, compared to small amount with SAB.
- True
- Dural cuffs or sleeves have a proliferation of arachnoid villi and granulations which reduce the thickness of the dura mater permitting rapid diffusion into the CSF.
What are LA diffusion rates with epidurals altered by?
Physiochemical properties of anesthetics:
- Lipid solubility
- Protein binding
T or F: The more lipid soluble and protein-bound of the LA injected into the epidural space, the less likely it will diffuse out of the area.
-True, it will usually stick around where you inject it.
What will happen if morphine is injected into the epidural space (only 30% protein bound)?
It will travel rostral all the way to foramen magnum
Is there any reason that an epidural can be done, but a spinal is contraindicated?
NO…both procedures have the same contraindications; if you can’t do one, you shouldn’t do the other
How much curvature does the Touhy needle have?
- 30 degrees
- blunt tip less likely to pierce subarachnoid space
How much curvature does the Hustead needle have?
- 15 degree curve
- more easily pierces skin and ligamentum flavum
Which needle is usually used for thoracic epidural placement, due to steep angle needed, or also if catheter advancement is difficult?
-Crawford needle
T or F: The gauge of the epidural is typically 2 gauges less than the epidural needle.
True
If you have an 18 gauge epidural, what size gauge would the epidural catheter be?
20 gauge
What are the types of epidural catheters?
- Single-holed, open-ended (uni-port)
* Lateral-holed, closed-tip (multi-port)
Between which structures is the epidural space located?
Between Ligamentum Flavum and Dura Mater
With the Paramedian or Lateral epidural approach, which two areas are bypassed, compared to the midline approach?
- Supraspinous ligament
- Interspinous ligament
How is total epidural dose calculated?
Volume x Concentration
What effects the density of the block?
Concentration
What affects the spread of LA throughout epidural space?
Volume
What direction does epidural block occur fastest?
Cephalad
T or F: Epidural space size increases down the spinal cord, as the cord occupies less space.
True
How many ml’s of LA are needed per segment to block cervical and thoracic epidural space?
0.7-1 ml/segment
How many ml’s of LA are needed per segment to block lumbar are needed?
1.25-1.5 ml/segment
T or F: In the elderly and pregnant patients, spread of LA is greater (3-4 dermatones), so only 0.5-1 ml/segment is needed.
True
T or F: If primary purpose of epidural is to provide complete surgical anesthesia, a higher concentration must be used.
True
T or F: The “take-home” drug volume dose for epidurals is 1-2 ml/dermatomal segment to be covered, with elderly and pregnant patients needing less than general population.
True
When an opioid is injected epidurally, where are the opioid receptors located in the spinal cord?
-In the substantia gelatinosa (Rexed Laminae II)
In order to achieve adequate analgesia from epidurally administered opioids, the dose is increased _____ the amount needed for intrathecally injected opioids.
10 X
If 100 mcg of morphine is injected intrathecally, what is the dose required epidurally to have the same effect?
1 mg
*epidural opioid dose correlates to IV dose of opioid
If 15 mcg of fentanyl is injected intrathecally, what is the dose required epidurally to have the same effect?
150 mcg
How much time does it take for maximum spread of LA to occur?
between 10-25 minutes
When sensory regression of 1-2 dermatomes occur, what is the dose given?
30-50% of the VOLUME of the initial dose
If sensory regression of 2 dermatomes occurs, and the initial epidural dose was 20 ml, what is the new dose given to get back those 2 dermatomes?
6-10 ml
What is a patchy block?
-One single place that has pain, but everywhere else is numb
What happens with a missed dermatome?
-There is a band all the way around the body that is not blocked, but above and below are numb
What happens with an inadequate block?
-Not enough volume given!
What is a rapid and high level epidural?
-epidural dose actually goes into subarachnoid space and patient is comfortable but NOT BREATHING
T or F: Complications of epidurals are same as spinals.
True:
- Hemodynamic changes
- Backache (#1 complication)
- PDPH
- Infection
- Neurologic Sequelae
