UPDATES ON
PEDIATRIC REGIONALANESTHESIA Foudan Shaltout Professor of Anesthesia Cairo University
History Dating back to ancient Egypt 2500 BC, regional anesthesia was emphasized for circumcision. August Pier in 1899 reported the first study on regional anesthesia in children. Bainbridge in 1901 successfully performed spinal anesthesia in infants and children, time when general anesthesia was relatively risky.
Why has the interest in PRA increased
over the last two decades ? Due to (1) The realization that children, even premature, feel pain. (2) PRA controls pain with less respiratory depression. (3) Improved safety of regional techniques due to increased clinical practice. (4) The introduction of more safe local anesthetic drugs.
What is the value of Pediatric Regional Anesthesia ?
(1) In conjunction with general anesthesia, PRA can control pain, hence reduce metabolic, endocrinal and neurobehavioral stress response. (2) Provide analgesia in postoperative period, hence reduce morbidity due to use of opioids. (3) Spinal anesthesia alone in the former preterm infants who are at risk of postoperative apnea.
What are the indications ?
In children who: (1) dread to be made unconscious. (2) with: - family history of malignant hyperthermia. - neuromuscular disease with reduced respiratory reserve. - chronic airway disease (bronchial asthma) (3) Former premature infant with a history of apnea. (4) Cooperative child undergoing emergency surgery with a history of recent food intake.
CONTRAINDICATIONS ? Absolute: (1) Infection at site of injection. (2) Lack of parent consent.
Relative: (1) Lack of patient cooperation. (2) Uncontrolled Seizures. (3) Difficult airway as intubation may be needed in case of toxic reaction. (4) Coagulopathy. (5) Anatomic anomalies at site of injection.
(6) Hypovolemia ( should be corrected before block). (7) Neurologic disease (may worsen or on legal basis).
What are the differences between child and
adult in relation to regional anesthesia? Physiologic (1) Neonates have reduced protein binding of local anesthetics which increase ratio of free drug and predispose to CNS toxicity. (2) Hepatic degradation of amide local anesthetic is slower up to 3-6 month of age. Anatomic (1) Epidural space is more superficial compared to that of adult. (2) Spinal cord ,in infants, ends at L3 while quda equina ends at S4.
What are the considerations in PRA? • Its usually performed with the patient asleep. • The dose is far less than for adult and should be calculated on mg/kg basis. • Look for ECG changes rather than physiologic parameters to test dose. • Reported complications to RA are far less in a child. • Always get parent consent and suggested get child’s approval at age 0f 12 (Tait etal 2003)
PRA awake or asleep?
Double the technique double the risk? -The
difficulty in placing regional anesthesia In a child is the inability of a child to cooperate as well as the cognitive inability to relate to symptoms as parasthesia or pain. - Hence the child is best provided with RA under deep sedation or after induction of general anesthesia. (Maria etal 2009) - Spinal block can be performed in the awake former premature infant to avid the risk of respiratory depression after GA. - In cooperative adolescent RA can be performed while the child is awake.
Local anesthetic drugs Maximum Recommended Doses and Approximate Duration of Action of Commonly Used Local Anesthetic Agents Local Anesthetics
Class
Max Dose (mg/kg)
Duration of Action (min)
Procaine
Ester
10
60–90
2-Chloroprocaine
Ester
20
30–60
Tetracaine
Ester
1.5
180–600
Lidocaine
Amide
7
90–200
Bupivacaine
Amide
2–4
180–600
Ropivacaine
Amide
2–4
180–600
Levobupivacaine
Amide
2–4
180–600
When used in IV regional anesthesia, the dose of lidocaine should be reduced to 3–5 mg/kg.
Lidocaine • Maximal recommended dose is 5 mg/kg (7mg/kg with epinephrine ). • For topical application to mucosa the concentration is 1-4%. • For infiltration 0.5%.
Bupivacaine Has a longer duration and less motor block. Caudal or epidural 0.125-0.25 %. Maximal recommended dose 2.5-3 mg/kg.
Levobupivacaine a new isomer which has relative potency with less CNS and cardiovascular toxicity.
Maximum infusion dose Infant: Child :
0.2 mg/kg/h 0.4 mg/kg/h.
Ropivacaine •Is less toxic with less motor block. Concentration used for caudal and epidural is 0.2%
Systemic Toxicity of Local Anesthetic Solution Central Nervous System Dizziness and lightheadedness Visual and auditory disturbances Muscle twitching and tremors Generalized convulsions Cardiovascular
Direct cardiac effects
Depressed rapid phase of repolarization of Purkinje fibers Depressed spontaneous firing of the sinoatrial node Negative Inotrophic effect on cardiac muscle Calcium influx altered leading to decreased myocardial contractility
Effects on vascular tone
Low concentrations-vasoconstriction High concentrations-vasodilatation Increased pulmonary vascular resistance
How to avoid local anesthetic toxicity? • Aspirate prior to injection. • Inject test dose (0.5-2 ml of local anesthetic solution containing 0.5ug/kg epinephrine). • Look for signs of positive test dose on ECG and blood presser. • Incremental injection of LA . • Always test catheter by a test dose before bolusing or starting continuous infusion.
PEDIATRIC REGIONAL BLOCK
CENTRAL CAUDAL EPIDURAL SPINAL
Peripheral
NERVE BLOCK
Ilionguinal/iliohypogastric Plexus Block for abdomen and genitalia (Brachial plexus block) Penile N B Intercostal N B
More recent, there is tendency to shift from neuro-axial to peripheral nerve block. Why? Peripherally targeted location of local anesthetic drugs can minimize the undesirable side effects of central block such as urinary retention, hypotension , muscle weakness and unaffected areas. (Allison etal 2000)
CAUDAL BLOCKADE
CAUDAL BLOCK • Safe • Easy to perform • Predictable postoperative pain relief for operation below diaphragm (T 10-S 5) • Used as a single shot after GA in a dose of: 0.5 ml/kg for sacral block. 0.75 ml/kg for lower abdominal. 1 ml/kg for mid abdominal block.
Technique • • • • •
Under aseptic conditions Position: lateral or prone Identify sacral hiatus. Use a needle 22-G x 1 inch long Pierce sacrococcygeal membrane at an angle of 45 degree lower angle to 15 and advance needle for 24 mm to avoid puncture of dural sac. • Identify space with loss of resistance to injected saline. • Do test dose with 2 ml of 0.125% Marcaine with epinephrine 1/200000 ( Increased HR means IV injection). • Give volume in incremental doses.
Continuous Caudal Block • Use 18-G needle 21-G catheter. • Used for longer procedures or to extend block above diaphragm.
Complications • Vascular puncture/accidental intravenous injection. • Systemic toxicity : tachycardia, dysrhythmias, hypotension, convulsion and cardiac arrest. • Dural puncture is rare but leads to total subarachnoid injection. • Sacral marrow puncture / injection leads to toxic reaction.
Epidural Anesthesia • It should be noted that a child is unable to elicit parasthesia under GA. • Sole Epidural Analgesia may not be feasible. • Risk/benefit should be judged. • Epidural catheter should be placed at the exact dermatomal level of nerve roots of the surgical site. • Verify by injection of a small volume of hypoallergic dye and X ray.
Use
Epidural Thohy needle 18-G Catheter 21-G Loss of resistance test Don’t forget test dose Dose Volume/Spinal segment = 0.1 ml x Age in years. Infusion rate for postoperative Analgesia 0.2 mg/kg/h.
ILIOINGUINAL/ILIHYPOGASTRIC Nerve block
ILIOINGUINAL/ILIOHYPOGASTRIC NERVE BLOCK
• These nerves are major branches of lumbar plexus (L1 & T12, L1). • It is easy to perform and provides posoperative analgesia for inguinal herniotomy, varicocele ligation and orchidopexy. • Position: supine.
• • • •
Technique Site of puncture is 1cm medial and 1cm inferior to anterior superior iliac spine above inguinal ligament. Needle 22-23 G short blunt at a right angle to skin. Feel the click then inject local anesthetic while withdraw the needle. Dose 2mg/kg Marcaine (10ml of 0.25%).
PENILE NERVE BLOCK
PENILE NERVE BLOCK Indication : for procedures on external genitalia eg. Circumcisionhypospedias repair. The aim is to block the two dorsal nerves of the penis that run along the dorsal artery that supplies penis at the level of symphysis pubis ( note that this artery is a blind artery so never use epinephrine).
Technique (1) Ring block at the base of the shaft of the penis. (2) Dorsal nerve block: at a point 1cm above symphysis pubis with 27 G needle inserted at 30 degree. Aspirate and inject 4ml of local anesthetic (or 2 injections at 11 & 1 Oclock)
Sciatic Nerve Block Posterior approach
SCIATIC NERVE BLOCK • For lower limb block (L4, L5, S1-S3). • Use nerve stimulator. • Position: Sim,s position for posterior approach. • Landmarks Greater trochantar, posterior superior iliac spine and tip of coccyx. • Needle 22-G 3.3-inch spinal needle perpendicular to skin. • Dose: 0.2-0.5 ml/kg of 0.25% Marcaine.
Anterior approach for sciatic n. block • Position: supine. • Landmarks: inguinal ligament (a point between lateral 1/3 and medial 2/3) & Greater trochanter ( a line extended medially to meet a perpendicular line drawn from the last point. • Needle 22-G 3.5 inch spinal needle
BRACHIAL PLEXUS BLOCK (1) AXILLARY BLOCK (2) PARASCALENE BLOCK Needle 22-23-G short bevel. Volume: < 1year 3 ml. >1 year 0.6-0.7 ml/kg. Dose : 2-3 mg/kg.
We have to admit that the implantation of PRA in daily clinical practice is still lacking. The main problem include appropriate selection of the block and how to teach these techniques in an optimal manner. (Marhover 2012 Every day PRA)
Conclusion Regional anesthesia can improve the overall anesthetic care provided for children. It can be used as a sole anesthetic in the former preterm infant to avoid post operative apnea or in the older cooperative children. Regional blockade when performed under GA should be guided by a nerve stimulator. CT and ultrasound guided techniques have facilitated more accurate placement of needle and less complications. The newer less toxic local anesthetic drugs should be preferred and the maximum dose should not be exceeded.
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