Pediatric spinal anaesthesia

Pediatric spinal anaesthesia

1. Pediatric Spinal Anesthesia Presenter: Dr. Suresh Pradhan Moderator: Dr. Upendra Krishna Regmi

2. History J. Leonard Corning is credited with discovering and administering the first spinal anesthesia in 1885 which was published in a medical journal regional anesthesia in children was first studied by August Bier in 1899 SA was known to be practiced for several years with a series of cases published as early as in 1900-1910

3. in 1900, Bainbridge reported a case of strangulated hernia repair under SA in an infant of three months Tyrell Gray published a series of 200 cases of lower abdominal surgeries in infants and children under SA in 1909-1910 1983, in the American Society of Anesthesiologists Regional Anesthesia Breakfast Panel, Abajian et al started the “frenzy” of modern pediatric SA when they reported 78 cases in 81 infants

4. however, pediatric spinal anaesthesia never achieved its popularity because of continuous discoveries of newer and better volatile agents and muscle relaxants for general anaesthesia although SA is today considered safe and effective for pediatric patients, it remains underutilized compared to GA

5. in the last decade, it started being advocated again by many centers due to increasing knowledge on pharmacology safety information availability of specialized equipment for regional anesthetic techniques and monitoring in children in the coming times, pediatric spinal anaesthesia will not only be used in cases where general anaesthesia is risky or contraindicated but also be the preferred choice in most lower abdominal and lower extremity surgeries in children

6. spinal anaesthesia provides a good alternative to general anaesthesia in newborns with increased anaesthesia-related risk for infants undergoing lower abdominal or lower extremity surgery during the first 6 months of life it is most successful as a single shot technique, limited to surgery lasting less than ninety minutes spinal anaesthesia in children requires the technical skills of experienced anaesthesia providers

7. Anatomical and Physiological Considerations in Children spinal cord terminates at a much more caudad level in neonates and in infants compared to adults it ends approximately at L3 level at birth and at L1-L2 level in children over one year old dural sac in neonates and infants terminates in a more caudad location compared to adults--about the level of S3 compared to the adult level of S2

8. to avoid potential injury to the spinal cord, dural puncture should be performed below the level of the spinal cord, i.e. below L3-L4 in neonates and infants Tuffier's / Intercristal line crosses spinal axis at the L5-S1 level in neonates and infants up to one year of age at the L4-L5 level in older children landmark applicable in all pediatric patients

9. the distance between the skin and the subarachnoid space is influenced by age – from 10 to 15mm in newborns the distance between skin and subarachnoid space can be related to height or weight using the formulae: distance from skin to subarachnoid space (cm) = 0. 03 x height (cm) distance from skin to subarachnoid space (mm) = [2 x weight (kg)] + 7(mm)

10. the subarachnoid space in newborns is very narrow (6 to 8mm) and successful lumbar puncture in this population requires great precision and avoidance of lateral deviation CSF Volume:

11. the spinal/cerebral distribution of CSF also varies with age: Half the CSF volume is located within the spinal subarachnoid space versus only 25% in adults the volume of distribution of drugs injected into the subarachnoid space is higher in infants and neonates than in adults and consequently the injected dose is relatively greater in infants and neonates

12. Hemodynamic Consequences the physiological impact of sympathectomy is minimal or none fall in BP and a drop in the heart rate are practically not seen in children less than five years infants respond to high thoracic spinal anaesthesia by reflex withdrawal of vagal parasympathetic tone to the heart children >5 years of age behave like adults after SA

13. Respiratory Effects respiratory effects of SA are generally seen in association with high motor block above T6 children with severe chronic lung disease should receive supplemental oxygen or Continuous Positive Airway Pressure (CPAP) during SA

14. Pharmacological Concerns most important concerns with intrathecal LA in infants and young children is the risk of toxicity REASONS immature hepatic metabolism decreased plasma proteins

15. higher Cardiac Output and regional blood flow in infants also increase the drug uptake from neuraxial spaces can predispose them to local anesthetic toxicity decreases the duration of action decreased levels of plasma pseudocholinesterase - increased risk of ester LA toxicity

16. Indications preterm and former preterm infants who are prone to post-operative apnea, bradycardia and desaturation after GA less than 60 weeks post-conceptual age less than 3 Kg hematocrit <30% with other co-morbidities neonates with respiratory diseases like bronchopulmonary dysplasias , hyaline membrane disease

17. children with history of or at high risk for malignant hyperthermia children with acute respiratory conditions, chronic disease of the airways like asthma or cystic fibrosis for elective lower abdominal or lower extremity surgery

18. Contraindications coagulation abnormalities systemic sepsis or local infection at the puncture point uncorrected hypovolemia parental refusal neurological abnormalities such as spina bifda

19. progressive neurological disease increased intracranial pressure procedures lasting more than 90 minutes allergy to local anesthetics

20. Preoperative Preparation

21. Consent and risk-benefit aspect the technique should be explained fully to the parents (and child if appropriate), with a description of risks and benefits consent from the parents is an important issue before planning a central neuraxial blockade for children consent should be informed and written, and the various aspects of regional technique should be explained

22. a full blood count including platelet count and coagulation screen (PT, APTT) may be performed preoperatively where clinically indicated blood tests are not usually required for a routine herniotomy , the most common indication for infant spinal anaesthesia

23. NPO and Premedication the standard preoperative fasting guidelines are required to be followed before elective spinal anaesthesia Fasting for: 2-3 hours fasting for clear fluids 4 hours for milk/other liquids 6 hours for solids adequate premedication is the key to a smooth regional procedure in children

24. Various drugs via different routes may be used to achieve a well sedated child who allows venous puncture, placement of monitors and even a lumbar puncture oral combination of different drugs are used as premedication other routes of premedication like rectal, sublingual, nasal or intramuscular are also practiced

25. Midazolam PO 0.25-0.75mg/kg IV 0.025-0.1mg/kg IM 0.1-0.2mg/kg IN 0.2mg/kg PR 0.6-1mg/kg (15min prior) Diazepam - PO 0.1-0.3mg/kg, IM not recommended

26. Ketamine IV 0.25-0.5mg/kg(sedation dose) IM 1-2mg/kg PO 5-6mg/kg (sedated within 10-12min) Nasal 6 mg/kg (sedated within 20-40min) PR 5 mg/kg (sedation & anxiolysis with in 30 min)

27. Fentanyl 10 to 15 μg /kg PO 1 to 2 μg /kg-nasally Anticholinergic Drugs atropine 0.01 to 0.02 mg/kg glycopyrrolate 0.01 mg/kg scopolamine 0.005 to 0.010 mg/kg IV, IM

28. Technique of Spinal Anesthesia Preparation: EMLA cream or Ametop gel may be applied to the lumbar area, 60 to 90 minutes prior to SA the operating room should be warmed prior to bringing the patient into the room with older children, the room should be quiet and if possible, surgical instruments should be covered so as to minimize patient anxiety

29. newer operating rooms may be equipped with stereo or video equipment which may be used to distract older children if the block is performed while the child is awake or sedated standard routine monitoring and standard intravenous infusion should be started prior to performing the block

30. Operative Management : a plan should be made regarding the concomitant use of IV sedation or GA in preterm or former preterm infants undergoing lower abdominal procedures <90 min duration, it is common practice to perform SA without adjuvant sedation and to conduct the anesthesia without supplemental IVA or GA

31. older children may require supplemental sedation or light general anesthesia prior to performing the block in some cases, SA may be combined with caudal or epidural anesthesia

32. Patient Position: there should be an assistant for the anesthetist to help with preparation of the equipment, positioning and holding the child during SA can be performed with the patient in the lateral decubitus position or sitting if the sitting position is preferred, ensure that the neck is not flexed which may result in airway obstruction

33. in older children, the assistant should maintain good positioning and reassure & distract the child while the block is being performed essential to monitor the SPO 2 of the infant while performing spinal anesthesia to ensure the adequacy and patency of the airway

34. Wrong Positioning

35. Technique all drugs and equipment should be prepared and checked prior to starting full barrier aseptic technique should be used, with a sterile work surface for equipment the operator should use sterile gloves, gown and mask and the patient’s skin should be cleaned with an antiseptic solution

36. the skin should be allowed to dry and a sterile sheet should be placed over the child with a hole to reveal the field the dose of local anesthetic solution is calculated according to the weight of the child the drug should be drawn into a 1-2ml syringe as appropriate and placed on the sterile work surface prior to dural puncture

37. Dose of Local Anaesthetic for SA in Children

38. in infants, the L4-5 or L5-S1 interspace and in older children L3-4 interspace, may be used for lumbar puncture if EMLA cream or Ametop gel were not applied, local anesthesia should be administered prior to the block in awake or sedated children

39. various sizes and lengths of needles are available depending on the child’s age 25G or 26G needle with stylet are used for neonates and infants length of spinal needle varies from 25-50 mm 25-30 mm for infants 50 mm for small children 90 mm adult spinal needle in older children

40. both cutting and pencil point needles have been used with similar success a short bevel allows better appreciation of tissue resistance and reduces the chance of incomplete injection of drug IV catheter's hollow stylet and hypodermic needles can also be used

41. a free flow of CSF should be obtained when the spinal needle is advanced into the intrathecal space depth of insertion at L4-L5 level varies with age newborn 10-15 mm up to 5 years 15-25 mm 5-8 years 30-40 mm

42. a midline approach is recommended over a paramedian approach ligamentum flavum is very soft in children and a distinctive "pop" may not be perceived when the dura is penetrated once clear CSF is seen exiting the needle, drug should be injected slowly barbotage method is not recommended the caudal end of the patient should not be elevated

43. Assessing the block assessing the level of blockade may prove difficult in infants and young children in infants, pin prick or their response to cold stimuli can be accessed by observation of their rate and pattern of ventilation

44. in infants and sedated patients, transcutaneous electrical stimulation is a better and reproducible method in children > 2 years Bromage scale can be used inability to move the blocked extremity after emergence is a good evidence of successful block

45. Intrathecal drugs among the various drugs approved by FDA for pediatric intrathecal use, 0.5% hyperbaric bupivacaine and tetracaine are common and popular ropivacaine and levobupivacaine are not currently approved for spinal administration in pediatric patients

46. Pediatric Spinal Anesthesia contd …

47. Recovery and discharge before shifting the patient to recovery room- ensure stable vital signs intact gag swallowing cough reflexes adequate respiration

48. criteria for discharge should include ambulation (appropriate for age) orientation to time, place and person appropriate for child's age tolerating oral fluids with minimal nausea and vomiting voiding, though not necessary, helps establish fluid status and degree of residual block

49. If residual sensory block is present, instructions to protect the child from hot, cold, or sharp objects should be given

50. Limitations duration is an important and a limiting factor for pediatric SA especially in infants and younger children restricted to one hour duration surgeries only duration of long acting local anesthetics like bupivacaine is only about 45 min in neonates and 75-90 min in children upto five years

51. need for sedation and GA in some children for performance of block and despite successful block during the surgery technical difficulties pediatric spinal needles are expensive and may not be freely available

52. Advantages of SA over GA SA is a cheaper due to rapid recovery shortened hospital stay more procedures performed on day care basis provides all components of balanced anesthesia with minimum cardio-respiratory disturbances less chances of PONV early ambulation rapid return of appetite

53. tracheal intubation and respiratory effects of GA and IV opioids can be avoided in high-risk patients with limited respiratory reserve more effective in blunting the neuroendocrine stress and adverse responses to surgery preferred choice in a child at risk of developing Malignant Hyperthermia

54. Adverse Effects and Complications the complications related to spinal anaesthesia are usually either due to the needle used to perform the procedure (backache, headache, nerve or vascular injury and infection) or the drugs injected (high or total spinal, drug toxicity) however, little data is available regarding the incidence as compared to adults.

55. Cardio-respiratory insufficiency : Hypotension and desaturation are rare in children High or total spinal anesthesia : (0.6%) can result if infant's legs are lifted after injection of drug or with overdose and barbotage Backache : (5-10%) is a common complaint, but its causal relationship has not been established.

56. incidence of PDPH is less in children compared to adults Kokki et al studied on 200 children using two different sizes spinal needles of 25 G and 29 G Quinke , found that 10 had PDPH with no difference regarding the type of needle used transient neurological symptom (TNS) has been reported by some authors following SA due to direct toxicity of large doses of local anesthetics

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