Neonate with Meningomyelocele for Surgical Repair Case Discussion

1
Neonate with Meningomyelocele for Surgical
RepairCase Discussion

• Prof Elsa Varghese

2

• What would you ask in the history
• look for when you examine this neonate?

3
(No Transcript)
4
History Examination

• Pre-natal hx, method of delivery complications
• Gestational age
• Medications antibiotics re meningitis
• Family history
• Physical Exam
• Vital signs
• Neurologic deficits
• Associated anomalies
• Volume status ? fluid deficit
• Vascular access adequate?

5
Clinical Evaluation of Dehydration
?
Appearance
Skin turgor
Pulse
BP
Fontanelle
Capillary Refill time
Eyeballs
Mucous membranes
Urine output
Respiration
6
Do you Need Laboratory Investigations
CBC, electrolytes blood sugar Echocardiogram
7
What Does the Surgery Involve

• Goal closure within 24-72hr of delivery
• Surgical Goals
• Close dural defect, stop CSF leak
• Prevent infection
• Preserve neural function
• Prevent secondary tethering of spinal cord
• Surgical Technique
• Separate neural placode
• Dissection of the dura
• Approximation of tissues in midline
• Closure of dural sac, skin defect (may require
  rotational flap if defect large)

8
What are our Anaesthetic Concerns Management ?

• Airway
• Positioning
• Fluid management
• Monitors
• Breathing circuit and their flows
• Temperature
• Pain
• Latex allergy

9
Preparation
Hand washing
Warming devices
Small volumes
Drug tray
Monitoring equipment
10
Inhalation anesthetic over dosage
? uptake CVS depression
Bradycardia (fentanyl) Delayed clearance
(sedation, respiratory ?)
opioids
Sepsis CCF Prematurity
Altered pharmacokinetics/ kinetics
Careful titration of all medications for the
desired response
11
Airway Management
Can be a challenge !
Hypoxia
High oxygen consumption ? FRC

• Appropriate airway equipment
• Assisted mask ventilation, scoline,atracurium
• Sedated-awake / awake intubation
• Oxyscope
• Cuffed vs. uncuffed ETT, reinforced?
• Avoid long acting muscle relaxants
• neural element identification

12
Meningomyelocele Repair

• Positioning for intubation surgery
• Supine or lateral for induction, airway
  management
• Donut for protection of defect from pressure,
  trauma if supine
• Prone for repair

13
Anesthesia Maintainance, What Drugs?

• Induction inhalation/IV
• IPPV, circuit
• ETT tube size , length (precautions to avoid
  endobroncheal intubation)
• Maintenance ?N2O
• Inhalation agent
• Analgesia
• LA

14
Neonates Are Extremely Vulnerable to Hypothermia
Neutral thermal environment Heated
incubators Radiant warmers Fluid
warmers HME Forced air warmers Warmed surgical
solutions Plastic wrap Padding
15

• May need high FiO2
• SpO2 93-96
• Retinopathy of newborn

Oxygenation during GA
Mode of ventilation

• Assisted /Controlled ventilation
• Maintain normal PaO2, PaCO2
• Be alert to changes in airway pressures
• (blocked, kinked ETT
• May develop restrictive defect with large closure

16
Maintenance Fluids, Electrolytes Glucose
Management

• Neonates are sensitive to dehydration
• and fluid overload
• Calculate Deficits maintenance fluid
• Blood loss
• Replace CSF loss with NS/RL
• Include volumes administered with drugs
• Glucose solutions additional losses
• replaced with balanced salt solutions
• Tendency for hypoglycemia (serum glucoselt40 mg
  mL-1)

17
Neonates- Intraoperative Glucose Fluid
Replacement
Low glycogen stores Impaired gluconeogenesis
Maintenance fluid 1-3 days 10 Dextrose in
0.18 Saline _at_ 60 mL kg-1day-1
(5 mL kg-1
h-1) gt3 days 5-10 Dextrose in 0.75 Saline _at_ 4
mL kg-1h-1 20 mEq NaHCO3 20 mEq L-1 KCl
(Klt3.5 mEq L-1)
Replace any further perioperative losses with
Ringers lactate or 0.9 normal saline
Ellis D. In Motoyama EK, Davis PJ ed. Smiths
Anesthesia for infants children 2006.p.109-52
18
Emergence

• Confirm adequacy of analgesia
• Confirm adequate spontaneous ventilation
• Beware vocal cord paralysis, stridor
• Be prepared for emergent re-intubation

19
Postoperative Period
Alert !
Sepsis
Apnoeic spells carefully monitor

• ICU setting for post-op monitoring
• Prone or lateral position
• Monitoring for CSF leak, infection, hydrocephalus

20
Spinal Anesthesia for Closure of MMC

• Viscomi et al. Anes Analg 199581492-5
• Case series
• n14 neonatal lumbo-sacral MMC closures
• Prone positioning with chest roll
• Hyperbaric tetracaine 0.5 injected at caudal
  border
• Supplemental intrathecal tetracaine infused by
  surgeon PRN for crying related to surgical
  manipulation
• Fussy infants given pacifier /- midazolam for
  sedation 9/14
• Post-op apnea monitoring x 36 hrs with impedance
  monitor
• Results
• Spinal anesthesia 100 successful
• Supplemental spinal anesthesia required in 50 _at_
  93/-14 minutes
• 2 post-op respiratory events correlated to dose
  of midazolam
• Considerations
• Contraindicated with local infection
• Uncontrolled neonatal airway in prone position

21
Fetal Surgery for MMC Closure

• Animal studies suggest in utero closure of MMC
  defect may
• mitigate neurological damage
• decreased incidence of hydrocephalus
• Two Hit Hypothesis
• First Hit failure of neuralation ? open defect
• Second Hit amniotic fluid induced spinal cord
  injury CSF leak through neural tube defect

22
Prenatal Diagnosis

• Pre-natal ultrasound 18wk GA
• Inter-operator variability
• Sensitivity increases with risk of NTD
• 60 low risk, 89 high risk
• a-Fetoprotein levels
• Sensitivity 64
• Non-specific
• Combined 86 sensitivity

23
Etilogy

• Nutritional deficiency / Metabolic defect
• Folate 0.4mg/day US Public Health Service
• Decrease risk of NTD by 70
• Teratogens
• Valproic acid, carbamezapine, cytochalasins,
  calcium channel blockers
• Genetics
• Lower risk in blacks(13000), increased risk
  caucasian (11000)
• Increased risk if previous child with NTD

24
What are the Systemic Effects of Meningomyelocele

• CNS Open defect CSF leak
• ? High infection risk
• ? Damage to exposed neural tis
• Flaccid paralysis below lesion
• Sensory deficits
• Bladder / Bowel dysfunction
• Hydrocephalus (15 at primary closure ? 90 post
  closure (VP shunting)

25
Arnold-Chiari Malformation Type II
Small posterior fossa Caudal displacement of
cerebellum medulla and pons into cervical canal
80 incidence with MMC 20 develop symptoms of
brainstem dysfunction Dysphagia Poor
feeding Recurrent Aspiration Vocal cord paralysis
Stridor Apnea Abnormal responses to hypoxia,
hypercapnea BEWARE extreme head flexion ?
brainstem compression
26
Other Systemic Effects

• Pulmonary
• Sequellae of recurrent aspiration
• Possible restrictive pulmonary function
  post-closure
• Kyphoscoliosis
• CVS
• Congenital cardiac defects 40, FgtM
• Secundum ASD most common then VSD
• GI
• Neurogenic bowel dysfunction / incontinence

27

• GU
• Bladder extrophy
• Neurogenic bladder dysfunction
• Urinary incontinence/obstruction
• Recurrent UTIs/pyelonephritis
• Bladder dysfunction ? chronic vesico-ureteric
  reflux
• Renal dysfunction ? ESRD
• MSK
• Kyphoscoliosis
• Clubfoot
• Hip dislocation
• Flexion Contractures

28
Key Points

• Possibility of pressure trauma, operate at the
  earliest
• Look out for other congenital anomalies
• Problems with positioning for induction,intubation
  , prone
• Hypothermia, fluid deficit if major CSF loss
• Challenge of anesthetizing the neonate
• Likely to come for further surgical procedures
• Latex alergy in the older child