Regional anaesthesia in children

1
Regional anaesthesia in children
Presenter B. Uma Moderator Dr. Asha Tyagi
University College of Medical Sciences GTB
Hospital, Delhi
email anaesthesia.co.in_at_gmail.com
www.anaesthesia.co.in
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
Anatomic factors Anaesthetic implications
Lower termination of spinal cord (L3-4) Increased risk of direct trauma to the spinal cord Avoid epidural approaches above L3
Lower projection of dural sac (S3-4) Increased risk of inadvertent penetration of the dura mater
Delayed myelinization of nerve fibers Easier intraneural penetration of local anesthetics Onset time shortened Diluted local anesthetic as effective as more concentrated anesthetic
9
Anatomic factors Anaesthetic complications
Cartilaginous structure of bones and vertebrae Danger of direct trauma and bacterial contamination of ossification nuclei Use short and short beveled needles
Lack of fusion of sacral vertebrae Persistence of sacral intervertebral spaces
Delayed development of curvatures of the spine Same orientation of epidural needles at all level before 6 months of age
Changing axis of coccyx and absence of growth of sacral hiatus Identification of sacral hiatus difficult above 6-8 years Increased failure rate of caudal anesthesia
Delayed ossification and growth of iliac crests Tuffiers line passes over L5-S1 interspace
10
Anatomic factors Anaesthetic implications
Increased fluidity of epidural fat Increased diffusion of local anesthetic up to 6-7 years of age with excellent caudal blockade
Loose attachment of sheaths and aponeuroses to underlying structures Larger volume of LA for epidural blocks due to leakage along spinal nerve roots Increased spread along nerve paths with danger of penetrating remote anatomic spaces and blocking distant nerves
Sympathetic immaturity, diminished autonomic adaptability of the heart, smaller vascular bed in lower extremities Hemodynamic stability during neuraxial blocks Fluid preloading and use of vasoactive agents unnecessary
11
Pharmacologic factors Anaesthetic implications
Low plasma protein content (HSA and AAG) Increased unbound free fraction of all local anesthetic greater danger of systemic toxicity
Increased cardiac output and heart rate Increased regional blood flow resulting in increased systemic absorption of LA shorter duration of action
Enzymatic immaturity Slower metabolism of LA with risk of accumulation
Increased extracellular fluids Increased distribution volume and mean body residency time of LA with increased risk of accumulation after continous infusion
12
Pharmacologic factors Anaesthetic implications
Red cell storage In neonates high hematocrit values and enlargement of erythrocytes result in consistent entrapment of LA In infants physiologic anemia reduces red cell storage protective effect against systemic toxicity of LA
Pulmonary extraction Children with right-to-left shunts undergo considerable increase in arterial plasma concentration of LA due to pulmonary bypass
Absorption from epidural space The time (Tmax) to reach peak plasma concentration (Cmax) remains basically unchanged Ropivacaine and Levobupivacaine Tmax is prolonged up to 2 hours in infants and Cmax is increased Reduced continous infusion rates/repeat injections dosage
13
Pharmacologic factors Anaesthetic implications
Metabolism Low plasma cholinesterase activity Decreased cytochrome P450 activity Phase 2 reactions immature upto 3yrs of age
Elimination half life gt1yr same as adults lt 1yr increased thus favoring accumulation with repeated injections
Systemic toxicity Thresholds of toxicity of the unbound form of LA 0.3 µg/ml for bupivacaine 0.6 µg/ml for ropivacaine
Hepatic extraction and clearance of aminoamides High hepatic extraction ratio GFR 30 of adult values
14
Pharmacologic factors Anaesthetic implications
Opioids morphine Elimination half-life of neuraxial opioids increase in neonates and infants CSF concentrations very high after epidural injection takes 12 to 24 hours before their decrease below minimal effective concentrations (near 10 ng/mL)
Fentanyl, sufentanil Acute respiratory depression (sudden apnoea)
Additives Clonidine Clearance in neonates is approximately one third that in adults owing to immature elimination pathways Several instances of respiratory depression in neonates and small infants Should be avoided during the first 6 month of life.
15
Commonly used additives in pediatric RA
Additive Recommended doses Maximum doses
Morphine Epidural Intrathecal 30 µg/kg 10 µg/kg 50 µg/kg 20 µg/kg
Fentanyl (epidural) 1-1.5 µg/kg 2.5 µg/kg
Sufentanil (epidural) 0.25-0.5 µg/kg 0.75 µg/kg
Clonidine (epidural) 1-1.5 µg/kg 2 µg/kg
Ketamine (epidural) 0.5 mg/kg 1 mg/kg
16
Psychological factors Anaesthetic implications
Delayed acquisition of body scheme and conceptualization, anxiety Inability of patients to locate precise body areas Concept of paresthesia not understandable Difficult cooperation Heavy sedation or general anesthesia is required in most patients
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 lt30 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, mucocutaneous
  leisons-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 tumoral process
• True allergy to local anesthetics
• Chemotherapies (such as with cisplatin)
• Uncorrected hypovolemia
• Cutaneous or 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 neurotoxic solutions
• 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 anaesthetic and
  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

Local anaesthetic Usual conc. Max dose of plain soln mg/kg Max dose with epinephrine mg/kg
Lidocaine 0.25-0.2 5 10
Bupivacaine 0.125-0.5 2 3
Levobupivacaine 0.125-0.5 3 4
Ropivacaine 0.1-10 3 Not recommended
26
Selection of equipments.(contd.)

• Selection of block needles and catheters

Block procedure Recommended device
Spinal anaesthesia Spinal needle (24-25 gauge 30, 50 or 100 mm long, Quincke bevel, stylet)
Caudal anaesthesia Short (25-30 mm) and short beveled (45-degree) needle with stylet
Epidural anaesthesia Tuohy needle (22, 20, and 19/18 gauge) LOR syringe and medium epidural catheter
PNB Insulated 21-23 gauge short beveled needles
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
Parameters Scores
Level of consciousness Fully awake Arousable on calling No response 2 1 0
Oxygen saturation gt90 on room air gt90 on oxygen lt90 on oxygen 2 1 0
Circulation/ BP SBP within 20mm Hg of pre sedation values SBP within 20-50 mm Hg of pre sedation values SBP gt50 mm Hg of pre sedation values 2 1 0
Movement /activities Moves all extremities on command Moves 2 extremities Does not move 2 1 0
Respiration able to breathe and cough freely Dyspnea is with shallow breathing Apneic 2 1 0
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
  lt60 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
• gt2yr longer needle, smaller guage
• Pop felt as needle enters the ligamentum flavum
• 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.)
Local anaesthetic (neonates) Dose mg/kg Volume ml/kg
0.5 bupivacaine isobaric/hyperbaric o.5-1 0.1-0.2
0.5 levobupivacaine 1 0.2
0.5 ropivacaine 1.08 0.22
Local anaesthetic (children) Usual dose
0.5 bupivacaine isobaric/hyperbaric 5 to 15 kg 0.4 mg/kg (0.08 mL/kg)gt15 kg 0.3 mg/kg (0.06 mL/kg)
0.5 levobupivacaine 5 to 15 kg 0.4 mg/kg (0.08 mL/kg)15-40 kg 0.3 mg/kg (0.06 mL/kg)gt40 kg 0.25 mg/kg (0.05 mL/kg)
0.5 ropivacaine 0.5 mg/kg (max 20 mg)
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
• Sims 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 45 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 20
• 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

Bupivacaine in Concentration Dose Possible additives
Single dose caudal 0.175- 0.5 0.75- 1.25 ml/kg (max. 3 ml/kg) Epinephrine 2.5- 5 µg/kg Clonidine 1- 2 µg/kg Morphine 30- 70 µg/kg
Continous caudal 0.1- 0.25 0.4 ml/kg Fentanyl 2- 5 µg/kg
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 ligamenta flava
• 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
• Pectus excavatum repair
• Scoliosis corrective surgeries
• Controversial in cardiac surgeries
• Contraindications to epidural anaesthesia
• Severe malformations of spine and spinal cord
• Intraspinal leisons 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 conus
  medullaris
• Paramedian approach in spinous process anomaly or
  spine deformity
• Semiprone position with the side to be operated
  lowermost and the spine bent to enlarge the
  interspinous spaces
• 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.)
Agent Initial dose Continous infusion (max dose)
Bupivacaine, levobupivacaine Solution 0.25 with 5 µg/mL (1/200,000) epinephrineDoselt20 kg 0.75 mL/kg20-40 kg 8-10 mLgt40 kg same as for adults lt4 mo 0.15 mL/kg/hr of 0.125 or 0.3 mL/kg/hr of 0.0625 (0.2mg/kg/hr)4-18 mo 0.2 mL/kg/hr of 0.125 or 0.4 mL/kg/hr of 0.0625 (0.25mg/kg/hr)gt18 mo 0.3 mL/kg/hr of 0.125 or 0.6 mL/kg/hr of 0.0625 (0.3mg/kg/hr)
Ropivacaine Solution 0.2Dose same regimen in mL/kg as for bupivacaine Same age-related infusion rates in mg/kg/hr as for bupivacaine (0.1, 0.15, or 0.2)Do not infuse for more than 36 hr in infants lt 3 mo
45
References

• Bernard DJ. Regional anesthesia in children. In
  Miller RD, editor. Millers Anaesthesia. 7th ed.
  Philadelphia Churchill Livingstone 2010.
• Pawar D. Regional anaesthesia in pediatric
  patients. Indian J. Anaesth.200448(5).
• Davis PJ, Cladis FP et al. Smiths anaesthesia
  for infants and children. 8th ed. 2012.

46
Thank you
www.anaesthesia.co.in