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Regional Blocks

Terms in this set (34)

What five factors are considered for choosing a particular local anesthetic?
The choice of a local anesthetic will depend upon:

(1) the duration of surgery,

(2) the regional technique selected,

(3) the needs of the particular type of surgery (sensory block for obstetrics, motor block for orthopedics),

(4) the skills of the anesthetist, and

(5) the potential for systemic toxicity.

[Barash, Handbook, Clin. Anes., 1997, p224]
Rank the following local anesthetic injection sites from fastest/greatest absorption to slowest/least absorption: brachial plexus, caudal, lumbar epidural, intercostal, paracervical, subcutaneous.
The rate of absorption depends on blood flow to the tissue at the injection site.

Accordingly, intercostal > caudal > paracervical > lumbar epidural > brachial plexus > sciatic > subcutaneous.

[Morgan and Mikhail, Clin. Anes., 1996, p196; Cousins and Bridenbaugh, Neural Blockade, 1998, p114; Brown, Reg. Anes. and Analg., 1996, p193]
You perform an intramuscular injection (IM) of local anesthetic (trigger-point injection). Will the systemic rate of absorption be fast or slow?
Blood flow to resting (inactive) skeletal muscle is low (3 mL/min/100 grams). Hence, the rate of systemic absorption and the rate of increase in plasma concentration will be relatively slow.

Systemic absorption from intercostal, caudal, paracervical, and lumbar epidural is probably faster than systemic absorption from inactive skeletal muscle.

With intercostal injection, some absorption occurs from intercostal skeletal muscle, but keep in mind that this is an active muscle and thus has a much higher blood flow than inactive skeletal muscle.

[Guyton, TMP, 1996, p200; Authors]
The fastest absorption of local anesthetic and the fastest increase in plasma concentration of local anesthetic will occur after injection from which of the following sites: epidural, intramuscular, paracervical, subarachnoid, subcutaneous?
Paracervical.

[Authors; Morgan and Mikhail, Clin. Anes., 1996, p196; Cousins and Bridenbaugh, Neural Blockade, 1998, p114; Brown, Reg. Anes. and Analg., 1996, p193]
Name three situations in which epinephrine should NOT be used in a local block?
(1) Digital (toes or fingers) injection;

(2) penile injection;

(3) intra-ocular injection.

"Epinephrine is not used for peripheral nerve block because of possible end-artery vasoconstriction and subsequent tissue ischemia."

[Davison, et al., Mass. Gen., 1993, p222; Barash, Clin. Anes., 1997, p226]
What nerve may be blocked by injection of agent at the base of the tonsillar pillars?
Cranial nerve IX, the glossopharyngeal nerve, may be blocked intraorally by injecting 5 mL of local anesthetic into the base of each tonsillar pillar.

An angled 22-gauge 9 cm needle is employed for this technique. Careful aspiration before injection is mandatory because of the proximity of the carotid artery to the glossopharyngeal nerve.

[Miller, Anesthe- sia, 6th ed., 2005, pp 1708-1709]
How is proper position of a needle confirmed for transtracheal block?
Proper position of the needle is confirmed by aspiration of air prior to injection of anesthetic.

[Davison, et al., Mass. Gen., 1993, p303; Morgan and Mikhail, Clin. Anes., 1996, p70]
A transtracheal block is accomplished with what local anesthetic through what membrane with what gauge needle?
Transtracheal injection of plain lidocaine (4 mL of 4% lidocaine) through the cricothyroid membrane using a 22-gauge needle attached to a small syringe.

Lidocaine is sprayed into the trachea at end-expiration (Morgan and Mikhail) or during inspiration (Miller).

[Davison, et al., Mass. Gen., 1993, p303; Morgan and Mikhail, Clin. Anes., 1996, p70; Miller, Anesthesia, 1994, p1590]
What nerve is blocked when local anesthetic is applied through a trans- tracheal puncture?
Transtracheal puncture produces topical anesthesia below the cords, up and down the trachea.

Below the cords, the larynx and trachea are supplied by the recurrent laryngeal nerve.

[Cousins and Bridenbaugh, Neural Blockade, 1998, p504]
Why is the needle quickly withdrawn after injection for a transtracheal block?
The needle is quickly withdrawn after the injection, since the patient will begin to cough.

Coughing spreads the anesthetic over the surface of the trachea and the inferior surface of the vocal cords.

[Davison, et al., Mass. Gen., 1993, p303; Morgan and Mikhail, Clin. Anes., 1996, p70]
What is the maximum length of time the tourniquet should be inflated after a Bier block is given?
Two hours. Any damage to vessels, nerves, and skeletal muscle is usually reversible for tourniquet inflations of 1-2 hours.

"Tourniquet times should not exceed two hours."

[Barash, Clin. Anes., 1997, p1035; Davi- son, et al., Mass. Gen., 1993, p234|
What is the minimal amount of time required before the tourniquet should be deflated after administration of a Bier block?
Barash, 20-40 minutes; Mass Gen 25, minutes; Miller, 25 minutes.

[Barash, Clin. Anes., 1997, p684; Davison, et al., Mass. Gen., 1993, p237; Miller, Anesthesia, 1994, p1545)
Q13. What nerve can be blocked to reduce pain from I/IH06: Other Regional Blocks tourniquet inflation during an intravenous regional neural anesthesia (Bier block)?
To reduce pain from tourniquet pain encountered during an intravenous regional neural anesthetic (Bier block), the intercostobrachial nerve can be blocked by local anesthetic infiltration proximal to the tourniquet on the medial aspect of the arm.

[Miller and Pardo, Basics, 6th. 2011 p297
What volume of local anesthetic is injected into the arm for a Bier block? What volume of local anesthetic is injected into the leg for a Bier block?
25 mL 50 mL (Stoelting and Miller) or 40-50 mL (Morgan and Mikhail) is used for upper extremity Bier block.

100 mL 200 mL (Stoelting and Miller) or 60-75 mL (Morgan and Mikhail) is used for lower extremity Bier block.

[Stoelting and Miller, BoA, 1994, p189; Morgan and Mikhail, Clin. Anes., 1996, p262,272]
What local aesthetics are used for intravenous regional local anesthetic of the upper arm (Bier block)? What volume and what concentrations are administered?
40-50 mL of 0.5% lidocaine or 40-50 mL of 0.5% prilocaine are usually injected.

[Morgan and Mikhail, Clin. Anes., 1996, p262]
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