Chapter 122. Surgical Epidural

Toni Torrillo, MD

Figure 122-1. Choice of Epidural Needle

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A blunt, curved tip helps push the dura away and avoid inadvertent puncture. Straight needle facilitates catheter insertion but may increase the incidence of dural puncture. Reproduced from Morgan GE, Mikhail MS, Murray MJ. Clinical Anesthesiology. 4th ed. Figure 16-18. Available at: www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.

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Choice of Location

Location of surgery

Level of epidural placement

Thoracic

T4–8

Upper abdomen

T6–8

Middle abdomen

T7–10

Lower abdomen

T8–11

Lower extremity

L2–4

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Local Anesthetics

Agent1

Concentration (%)

Onset

Sensory block

Motor block

Chloroprocaine

Fast2
Fast

Analgesic
Dense

Mild to moderate
Dense

Lidocaine

≤1
1.5
2

Intermediate
Intermediate
Intermediate

Analgesic
Dense
Dense

Minimal
Mild to moderate
Dense

Mepivacaine

1
2–3

Intermediate
Intermediate

Analgesic
Dense

Minimal
Dense

Bupivacaine

≤0.25
0.5
0.75

Slow3
Slow
Slow

Analgesic
Dense
Dense

Minimal
Mild to moderate
Moderate to dense

Ropivacaine

0.2
0.5
0.75–1

Slow
Slow
Slow

Analgesic
Dense
Dense

Minimal
Mild to moderate
Moderate to dense

Fast and intermediate agents reach maximum block height in 15–20 minutes. Slow agents can take up to 30 minutes for maximum block height to be achieved.

1Always use preservative-free local anesthetic.

2Fast is approximately 5–10 minutes.

3Slow is approximately 15–20 minutes.

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Epidural Adjuvants

Adjuvant1

Dose

Onset (min)

Peak (min)

Duration (h)

Comments/side effects

Fentanyl

50–100 μg

5–10

10–20

1–3

Itching; nausea; urinary retention; sedation; ileus; respiratory depression (delayed with morphine—↓ dose with elderly or sleep apnea)

Morphine

2–5 mg

15–30

60–90

4–24

Hydromorphone

0.75–1.5 mg

20–30

1–3

Epinephrine

1:200,000

Prolongs nerve exposure to local anesthetic

Clonidine

150–400 μg

Hypotension; prolonged sensory block

Sodium bicarbonate

1 mEq/10 mL of local anesthetic

Hastens block onset with lidocaine, mepivacaine, chloroprocaine. Will precipitate with bupivacaine

1Opioids affect quality more than duration: they prolong the surgical block without significantly delaying recovery. Epinephrine prolongs chloroprocaine, lidocaine, and mepivacaine better than it does bupivacaine and ropivacaine. Peak blood levels of local anesthetic are lower with epinephrine.

Performance:

LORA/LORS—loss of resistance to air or saline
Advance needle with stylet through skin into interspinous ligament
Resistance should be felt
Remove stylet; attach glass syringe with 2–3 mL air or saline
Advance millimeter by millimeter until loss of resistance felt
Thread catheter 3–5 cm into epidural space
- Deep catheters prone to kinking/coiling
- Superficial catheters may dislodge
If difficulty finding epidural space, attempt to “walk off” bone or try a different level and/or approach
If persistent pain or paresthesia on threading catheter or injecting local anesthetic, remove catheter and try a different level. Ask patient which side the pain/paresthesia is and redirect needle in the opposite direction
Avoid injecting ...