Regional anaesthesia in children

1. Regional anaesthesia in children Presenter: B. Uma Moderator: Dr. Asha Tyagi University College of Medical Sciences & GTB Hospital, Delhi www.anaesthesia.co.in email: anaesthesia.co.in@gmail.com

2. Regional anaesthesia in children • Differences in anatomy and physiology • Selection of techniques, agents and equipments • Central neuraxial blockade in children including caudal block

3. Introduction • Regional anaesthesia in children first studied by August Bier in 1899 • In 1900, Bainbridge reported a case of strangulated hernia repair under spinal anaesthesia in an infant of three months • Tyrell Gray, a British surgeon published a series of 200 cases of lower abdominal surgeries in infants and children under spinal anaesthesia in 1909-1910

4. Introduction(contd.) • Advantages over GA: • Safe, reliable technique in infants at risk of apnoea, bradycardia and desaturation after GA • Good alternative for day care surgeries • Minimal risk of postoperative respiratory depression • Limited stress response to surgery • Cost effective

5. Perception of pain • Somatic pain has 3 components: • Motivational directive: • conveyed by unmyelinated C fibres • Slow/true pain • Fully functional from early fetal life • Leads to protective reflexes • Sensory discriminatory • Cognitive evaluative

6. Perception of pain(contd.) • Immature connections b/w dorsal horn neurons and C fibres till 2wks of life • Heightened response to nociceptive stimulation till 2 wks of life in response to large amounts of substance P • Immaturity of inhibitory control pathways till 2wks of life

7. Spinal cord anatomy

8. Relevant Differences between Children and Adults

15. Commonly used additives in pediatric RA

17. Indications of regional anaesthesia • Infraumbilical extraperitoneal surgeries like inguinal hernia, circumcision, hypospadias, orchidopexy, cystoscopy, colostomy for imperforate anus, rectal biopsy and other perineal surgeries • Lower extremity orthopaedic and reconstructive surgeries • Preterm and former preterm infants less than 60 weeks post-conceptual age/less than 3 Kg/hematocrit <30% and with other co-morbidities who are prone to post-operative apnoea,bradycardia and desaturation after GA

18. Indications(contd.) • Neonates with respiratory diseases like bronchopulmonary dysplasias, hyaline membrane disease • Children with h/o or high risk for malignant hyperthermia • Children with acute respiratory conditions, chronic disease of the airways like asthma or cystic fibrosis • Meningomyelocele, gastroschisis repair, open heart surgery etc in addition to light GA (rare)

19. Indications(contd.) • Management of nonsurgical pain • Herpes zoster, AIDS, mucocutaneousleisons-regional blocks • Vaso-occlusive crisis of sickle cell disease • Non analgesic indications • Sympathetic blockade for severe trauma • Vascular insufficiency in Kawasaki disease • Severe frostbite • Accidental intra arterial injection of LA

20. Contraindications to regional anaesthesia • Absolute contraindications to neuraxial blocks: • Severe coagulation disorders- constitutional or acquired • Severe infection such as septicemia or meningitis • Hydrocephaly and intracranial tumoralprocess • True allergy to local anesthetics • Chemotherapies (such as with cisplatin) • Uncorrected hypovolemia • Cutaneousor subcutaneous lesions at the contemplated site of puncture • Parental refusal

21. Contraindications( contd.) • Absolute contraindication to PNB procedures: • True allergy to the local anaesthetic agent • Relative contraindications: • Patients at risk of compartment syndrome • Sickle cell ds a/w hypoxemia and hemodynamic disorder • Extended malformations of vertebrae, spinal fusion, myelomeningoceles, open spina bifida, and major spondylolisthesis • Pre-existing neurologic disorder

22. Complications of regional anaesthesia • Local complications: • Inappropriate needle insertion damaging the nerve and surrounding anatomic structures • Tissue coring and introduction of epithelial cells into tissues where they do not belong • Injection of neurotoxicsolutions • Leakage around the puncture site which may cause partial block failure and favor bacterial contamination • Systemic complications: • Accidental iv injection of LA • Excessive dosing

23. Selection of materials, techniques and agents • Considerations for selection of suitable procedure: • Adequate sensory blockade • Minimal potential morbidity • Postoperative analgesia • Various approaches: • Single-shot technique with either a short-acting or a long-acting local anaesthetic • Single-shot technique with local anaestheticand adjuvants • Catheter technique with repeat/continuous injections of local anaesthetic

24. Selection of equipments….(contd.) • Identification of anatomic space: • Surface mapping or percutaneous guidance • Ultrasound techniques (Jockey probes) • Acoustic devices • Electrostimulation • Loss of resistance with air or saline • Whoosh test is now obsolete

25. Selection of equipments….(contd.) • Selection of anaesthetic agent depends on: • Site/ extent of surgery • Expected duration of intense postoperative pain • Hospital stay vs early discharge

26. Selection of equipments….(contd.) • Selection of block needles and catheters:

27. Safety precautions • Acceptable environment for performing regional blocks: • Minimal mandatory monitoring • Anaesthetic and emergency drugs • Resuscitation equipments • Trained anaesthesiologist • Trained staff • iv line in situ

28. Discharge criteria- Modified Aldrete score

29. Spinal anaesthesia • Anatomy and physiology: • The spinal cord and dural sac of infants younger than 1 year of age end at a lower level • Volume of CSF • 10 mL/kg in neonates • 4 mL/kg in infants weighing less than 15 kg • 3 mL/kg in children • 1.5 to 2.0 mL/kg in adolescents and adults • 50% CSF volume is located within the spinal subarachnoid space versus 25% in adults • Lower CSF hydrostatic pressure • Children older than 5yr behave like adults after spinal anaesthesia, whereas younger patients remain hemodynamically stable, without significant hypotension or bradycardia

30. Spinal anaesthesia(contd.) • Indications: • Inguinal hernia repair in former preterm infants <60 weeks of postconceptual age • Elective lower abdominal or lower extremity surgery • Cardiac surgery or cardiac catheterization (controversial)

31. Spinal anaesthesia(contd.) • Technique of spinal anaesthesia: • Position: • Lateral position with head extended to avoid airway compromise • Sitting position • Firm grasp of the awake infant by an assistant • Neonates and infants: 1.5” 22G spinal needle with stylet at L4-5 level • >2yr: longer needle, smaller guage • Pop felt as needle enters the ligamentumflavum • Free flow of CSF • Inject the LA slowly • Child to remain supine and legs should not be raised for any reason

32. Spinal anaesthesia(contd.)

33. Caudal anaesthesia Anatomy of sacral hiatus

34. Caudal anaesthesia(contd.) • Anatomy of sacral hiatus: • V-shaped aperture formed d/t lack of dorsal fusion of the 5th and 6th sacral vertebral arches • Limited laterally by sacral cornua • Covered by sacrococcygeal membrane • Mean distance from skin to anterior sacral wall: 21 mm (2 mo to 7 yr) • Less suitable after 6-7yrs as • Change in axis of sacrum • Difficulty to identify sacral hiatus • Densely packed epidural fat

35. Caudal anaesthesia(contd.) • Indications of caudal anaesthesia: • Surgical procedures below the umbilicus • As an adjuvant to GA • Sole anaesthetic technique in fully awake ex-premature infants younger than 60 wk of post conceptual age • Contraindications to caudal anaesthesia: • Major malformations of sacrum (myelomeningocele, open spina bifida) • Meningitis • Intracranial hypertension

36. Caudal anaesthesia

37. Caudal anaesthesia(contd.) • Technique of caudal anaesthesia: • Positioning the patient • Sim’s position • Semiprone • Prone- esp. in non anaesthetized (frog position) • Palpate for sacral cornua along the spinal processes at the level of sacrococcygeal joint • The sacral hiatus along with both PSIS forms an equilateral ∆ • Introduce needle in midline at 45⁰ or less • Resistance felt on piercing the sacrococcygeal ligament • Inject the LA with frequent aspirations • Finger should palpate the skin cephalad t the injection to ensure drug is not s/c

38. Caudal anaesthesia(contd.) • Technique using ultrasound: • Linear ultrasound transducer set at highest operational frequency to achieve max. resolution of the superficial anatomy • Transducer placed in longitudinal plane b/w 2 sacral cornua • Sacrococcygeal ligament identified • Needle introduced at 20⁰ • In difficult cases longitudinal paramedian approach

39. Caudal anaesthesia(contd.) • The armitage regime: • O.5 ml/kg- all sacral dermatomes blocked • 1 ml/kg- sacral and lumbar dermatomes blocked • 1.25 ml/kg- upto midthoracic levels blocked

40. Caudal anaesthesia(contd.) • Complications with caudal blocks: • Risks during performance of the block • Intravascular placement • Needle into subarachnoid space • Needle into sacral marrow • Risks from injection of LA • Side effects of other agents used • Block failure (3%- 5%)

41. Epidural anaesthesia • Anatomy and physiology of epidural space: • The epidural space surrounds the spinal cord and the meninges from the foramen magnum to the sacral hiatus • Limited posteriorly by the vertebral laminae and the ligamentaflava • Communicates quite freely with the paravertebral spaces • Near the spinal ganglia, connected with the subarachnoid space owing to protrusion of arachnoid granulations • Contains blood vessels and lymphatics • Filled with loose fat in infants and in children up to 6 to 8 years of age

42. Epidural anaesthesia(contd.) • Indications of epidural anaesthesia: • Major abdominal surgeries • Retroperitoneal, pelvic and thoracic surgeries • Pectusexcavatum repair • Scoliosis corrective surgeries • Controversial in cardiac surgeries • Contraindications to epidural anaesthesia: • Severe malformations of spine and spinal cord • Intraspinalleisons and tumors • Tethered cord syndrome • Hydrocephalus, unstable epilepsy • Previous spine surgery

43. Epidural anaesthesia(contd.) • Technique (for lumbar epidural anaesthesia): • Midline approach below L2-L3 interspace, which represents the lower limit of the conusmedullaris • Paramedian approach in spinous process anomaly or spine deformity • Semiproneposition with the side to be operated lowermost and the spine bent to enlarge the interspinousspaces • LOR with air in infants and saline in older children • Distance from skin to epidural space 1 mm/kg b/w 6mo- 10yr • Disconnect the LOR syringe • No reflux of biological fluid at hub • Catheter is inserted to not more than 3 cm in order to avoid buckling, knotting, and lateralization of blockade or erratic migration

44. Epidural anaesthesia(contd.)

45. References • Bernard DJ. Regional anesthesia in children. In: Miller RD, editor. Miller’s Anaesthesia. 7th ed. Philadelphia: Churchill Livingstone; 2010. • Pawar D. Regional anaesthesia in pediatric patients. Indian J. Anaesth.2004;48(5). • Davis PJ, Cladis FP et al. Smith’s anaesthesia for infants and children. 8th ed. 2012.

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