PEDIATRIC REGIONAL ANESTHESIA Jodie L. Johnson, M.D. Assistant Professor of Clinical Anesthesia Riley Hospital for Children

Introduction Regional anesthesia being used more frequently in pediatric setting Most blocks placed at beginning of case “preemptive analgesia” Some placed at end Rarely used as sole anesthetic

General Principles Must acquire experience/dexterity with RA in adults before employing techniques in kids Be aware of anatomical differences between small child and adult Be aware of pharmacokinetic differences

General Principles Consider individual drug profiles Skin infection in area of needle/catheter insertion is contraindication Coagulation disorders are contraindication (unless corrected) Chemotherapeutic agents cause vascular fragility and thus central blocks are contraindicated in pts on chemo

General Principles Have clear strategy Good organization of equipment, drugs and assistant helps avoid delays Close monitoring just as important as with GA

General Principles Significant development in regional anesthesia in peds due to: Advances in safety information Advances in pharmacology(Ropivicaine) Improvements in equipment Types of blocks limited only by skill and interest of individual anesthesiologist

Benefits Analgesia provided by block reduces amount of GA More rapid recovery Decreased incidence of nausea & vomiting Faster return of appetite Earlier discharge Decreased need for opioids

Benefits Regional block eliminates undesirable autonomic reflexes Laryngospasm decreased Cardiac dysrhythmias decreased Muscle relaxation can be obtained with suitable local anesthetic Can avoid use of muscle relaxants, decrease risk of respiratory insufficiency

Benefits Easier to obtain immobilization of limb after delicate surgery if child is pain-free and there is some residual motor block

Benefits Hypotension and urinary retention rarely seen in children Intra- and post-operative bleeding reduced under neural blockade A technique of choice if history of MH Can avoid interference with respiratory tract in premies with BPD

Benefits Diminished stress response Fewer episodes of hypoxia Greater cardiovascular stability Faster return of GI function Reduced need for postop vent support Shorter stay in ICU

Safety Low complication rates Lack of hypotensive response from sympathectomy produced by LA Loose perineurovascular sheaths Wider spead of LA from single injection site

Pharmacology and Physiology Increased risk of toxicity with local anesthetics Infants have immature hepatic metabolism Increased total body water Larger Volume of Distribution Longer elimination half-life Decreased plasma proteins ( more drug in free/active form) Rapid increase in blood levels due to higher cardiac output/regional blood flow

Pharmacology Long-acting local anesthetics provide for 6-12 hours of post-operative pain relief Bupivicaine 0.2% to 0.5% Ropivicaine 0.2%

Pharmacology Strictly follow maximal dosing guidelines to prevent side effects

Physiology Decreased minimum anesthetic concentration required to block impulse conduction Nerves have thinner myelin sheaths Nerves have smaller fiber diameter and a shorter internodal distance Adequate surgical block with smaller concentrations of LA

Equipment Appropriate equipment decreases risk of injury despite risks of increased toxicity Use nerve stimulator in anesthetized kids to improve success rate of peripheral nerve blockade 1- or 2-inch insulated needles used

Caudal Blockade Most common regional block in children Simple to perform Easily adaptable to ambulatory anesthesia practice Greatly decreases risk of reflex laryngospasm

Caudal - Anatomy Sacral hiatus easy to identify Palpable large bony processes on each side of hiatus called cornua Hiatus covered by sacrococcygeal membrane Dural sac may extend to S3 or S4 in infants (short distance between hiatus and dural sac)

Caudal- Technique Lateral decubitus position Palpate coccyx Move finger gently from side to side and proceed in cephalad direction First double bony protuberance encountered are sacral cornua which define the sacral hiatus

Caudal - Technique Sterile prep/drape 21 g butterfly needle usually used Insert at 45-60 degree angle with bevel facing anteriorly Distinct pop felt as sacrococcygeal membrane pierced Lower angle of needle and advance 2-3 mm

Caudal Blockade If outpatient, use just local anesthetic 0.25% Bupiv or 0.2% Ropiv with epi Test dose: 0.1 ml/kg with 5mcg/ml of epi (max 3ml) Look for signs of intravascular injection Increased heart rate > 10 bpm above baseline Increased blood pressure >25% change in T-wave amplitude Doses: 0.5cc/kg for LE/perineal surgery 0.75cc/kg for T-10 level 1cc/kg for lower thoracic level

Caudal Blockade For inpatients, can add PF MSO4 for 18 to 24 hours of postop analgesia 50 mics/kg for perineal surgery 60 mics/kg for mid abdominal incision 70 mics/kg for sternotomy (open hearts)

Caudal Blockade Recent interest in Clonidine ? Dose Less respiratory depression Less nausea/vomiting Less pruritis Similar/prolonged analgesia VS. Morphine ? Dose 1, 2 or 3 mcgs/ kg… to be determined

Caudal Blockade ? Use of Clonidine in outpatients Some staff do not use at all Some use if > 1 year of age ? Use of hydromorphone ? Use of ketamine

Caudal Blockade Major complications rare Intravascular injection with systemic toxicity Dural puncture causing high spinal blockade Infection (especially after interosseous puncture/penetration)

Continuous Caudal Catheter Manufactured kits available Styletted catheter increases passage to thoracic level Care taken to prevent fecal contamination

Continuous Caudal Catheter Caudal approach to thoracic epidural anesthesia used in children > 10 years of age Success related to less densely packed epidural fat Easy cephalad passage of catheter

Continuous Caudal Catheter Correct placement confirmed by: Ease of injection Negative aspiration Radiographic imaging Nerve Stimulation through catheter

Epidural Block Improved surgical outcomes: Decreased stress response Fewer episodes of hypoxia Decreased cardiac morbidity Decreased pulmonary infections Decreased thromboembolic events Decreased blood loss Faster return of GI function

Epidural Block Drugs Used: Ropivacaine/Bupivacaine 2 - Chloroprocaine Morphine Clonidine

Epidural Block Line drawn between two iliac crests passes closer to L5 (vs. L3-4 interspace in adults) Under 1 year of age: Spinal cord ends at lower level (L3 vs. L1) Dural sac ends at lower level (S4 vs. S2)

Epidural block Lateral decub position Surgical side down Hips and knees flexed by 90 degrees Sterile prep/drape “Loss of Resistance” technique with saline

Epidural Block Epidural space more superficial in children than adults Guideline for determining epidural depth: 1mm/kg of body weight Depth (cm) = 1 + 0.15 X age (years) Depth (cm) = 0.8 + 0.05 X weight (kg) Use shorter needles and extreme care

Epidural Block Dosing: Depends on upper level of analgesia required > 10 years of age: Volume to block one spinal segment V (in ml) = 1/10 X (age in years) < 10 years old: 0.04ml/kg/segment

Epidural Block Dosing:

Epidural Block Complications: Intrathecal injection High block Postdural puncture headache Intravascular injection/Local anesthetic toxicity Sympathectomy Hypotension Bradycardia

Epidural Block Complications: Opioid –induced respiratory depression Damage to neural structures Infection Epidural Hematoma  paraplegia < 1 in 150,000 Usually associated with anticoagulation

Epidural Block Although potential complications, there are multiple benefits Decreased stress response Decreased thromboembolic complications Decreased pulmonary problems Improved patient/parent satisfaction

Ilioinguinal and Iliohypogastric Nerve Block Simple Block Good pain relief for hernia repair, hydrocelectomy and orchiopexy Can be done at beginning of case for both intraop and postop analgesia May be done intraop under direct visualization

Ilioinguinal Nerve Block Anatomy Nerves run between abdominal muscles Close to ASIS Both blocked by infiltration in area medial to ASIS

Ilioinguinal Nerve Block 25-gauge needle Puncture skin 1 cm medial and 1 cm inferior to ASIS Three fan-shaped injections Sub Q wheal as needle withdrawn Bupiv 0.25% w/ epi up to 2mg/kg used

Penile Nerve Block Provides analgesia after superficial surgery of penis Circumcision Meatotomy Blocks both dorsal nerves at base of penis Anesthesia to distal two-thirds of penis

Penile Nerve Block Usually performed by surgeon Avoid epinephrine May lead to ischemia of tissue Complications: Intravascular injection Hematoma formation

Brachial Plexus Block Can be done at three levels: Axillary Interscalene Supraclavicular Excellent analgesia during/after surgery on the upper extremities

Brachial Plexus Block Axillary approach used most Major complications rare Interscalene/ Supraclavicular approaches provide better analgesia of upper arm/shoulder Higher complication rate : pneumothorax and subarachnoid blockade

Brachial Plexus Block Can perform with one-injection technique using nerve stimulator Insert needle at 45 degree angle immediately superior to artery high in the axilla Advance needle toward midclavicle until evidence of nerve stimulation distally

Brachial Plexus Block Can also be performed by feeling distinct “pop” upon entering perineuroplexus sheath After injection: Adduct arm Hold distal pressure on artery

Brachial Plexus Block Transarterial approach not recommended due to possible hematoma formation with secondary nerve compression

Parascalene Block Analgesia of shoulder joint Avoids major structures in neck Decreases chance of vascular injection Spares phrenic nerve

Parascalene Block Place supine with roll under shoulder Arm down at side Head extended and turned to opposite side Line drawn between midpoint of clavicle and transverse process of C6

Parascalene Block Insert needle perpendicular to skin at junction of upper two thirds and lower one third of drawn line Nerve stimulator used to determine depth Usually only 7 –30 mm below skin

Parascalene Block Complications: Puncture of external jugular vein Pneumothorax Horner’s Syndrome

Brachial Plexus Block Dosing: 0.3- 0.5cc/kg of 0.25% Bupiv or 0.2% Ropiv with 1:200,000 epi

Lower Extremity Blocks Lumbar Plexus (L1-L4) Sciatic Nerve (L4-S3) Femoral Nerve

Lumbar Plexus Block Provides analgesia to hip, thigh, groin Lateral decub position Lines drawn between iliac crests and parallel to spinous processes the through ipsilateral PSIS

Lumbar Plexus Block Insert needle 90 degrees to skin through quadratus lumborum Nerve stimulation appears as strong contraction of quadriceps muscle

Lumbar Plexus Block Complications rare Epidural spread may occur if needle place too medially

Summary Improvements in technique Refinements in equipment Regional anesthesia safely applied to children