Page 350 Guide to Pain Management in Low-Resource Settings

338 Corrie Avenant

What is the structure and technique would be as follows:
characteristics of a typical • Th e landmark is the base of the fi nger.
local anesthetic drug? • Insert the needle and make contact with the bone
(the proximal phalanx at its lateral point).
• Local anesthetics have a three-part structure • Withdraw the needle a bit and deposit 0.5–1 mL
• Th e three parts of the structure consist of an aro- of 0.5% bupivacaine.
matic ring, an intermediate chain, and an amino- • Redirect the needle dorsally and inject another
group 1 mL.
• Th e intermediate chain has either a ester or an • Repeat this on the other side as well.
amide linkage
Toe block
• Th e ester linkage gets broken down by hydrolysis,
has a short shelf-life, and is relatively nontoxic Indications would be fractures and amputations. As in
• Th e amide linkage is metabolized by the liver the fi nger, two nerves run on either side of each toe.
• Th e mode of action is a reversible block of nerve Th erefore the technique is the same as in fi nger blocks.
conduction by blocking the sodium channels Always use plain local anesthetics for digi-
(from the intracellular site) tal blocks; NEVER use mixtures with epinephrine
(adrenaline).
How is toxicity avoided Intravenous regional anesthesia (Bier’s block)
when using local anesthetics? Bier’s block may be a very eff ective block for upper and

lower limb manipulation, such as manipulation of sim-
• Always respect maximum doses: for bupivacaine
ple fractures and suturing of lacerations.
the maximum dose is 2 mg/kg for a single injec-
Th e method is as follows:
tion technique (daily maximum 8 mg/kg for con-
• Secure venous access on both sides.
tinuous techniques).
• Have a full resuscitation trolley available (in case
• In case of toxicity symptoms (slurred speech,
of cuff failure).
tingling in the ear, loss of consciousness, convul-
• The inflatable tourniquet is placed around the
sions, or arrhythmias), stop the injection, and ad-
upper arm over a wool bandage to protect the
minister oxygen and support ventilation to avoid
skin.
acidosis.
• A double cuff may be used for prolonged surgery
• Stop seizures with intravenous pentothal, benzo-
(>15 minutes).
diazepines, or propofol.
• Drain venous blood from the aff ected limb.
• If cardiac symptoms are present, give circulatory
• Infl ate the blood pressure cuff to 100 mm Hg
support (antiarrhythmics such as amiodarone or
above systolic blood pressure.
amrinone); if arrhythmias persist, use direct-cur-
• Inject local anesthetic.
rent (DC) cardioversion and cardiopulmonary re-
• Anesthesia is achieved after 10–15 minutes (the
suscitation (CPR) for as long as needed (which may
blood pressure cuff should not be defl ated within
be much longer than for other causes of arrest).
20 minutes).
• If available, use lipid infusion (Intralipid) to “an-
• Use 0.5 mL/kg of 0.5% lidocaine (plain) solution
tagonize” local anesthetic toxicity (a bolus of 1.5
mL/kg body weight of Intralipid 20%, followed by Intercostal nerve block
0.25 mL/kg body weight/minute for 1 hour).
A typical indication would be postoperative pain relief
after cholecystectomy or thoracotomy, as well as pain
What types of nerve blocks relief from fractured ribs. Remember that the intercos-
are easy to perform? tal nerves derive from the ventral ramus of the spinal
nerves and that they run along the inferior border of
Finger block the ribs. To block the intercostal nerves, use the fol-

Indications are fractures and lacerations. Th e two digi- lowing technique:
tal nerves run on each side of the fi nger. Th erefore, the • Position the patient in a supine position.