Jugular venous oxygen saturation (SjO2)

🔹 Assess  the balance between global cerebral oxygen delivery and utilization.

🔹 Normal SjO2 is 55–75%

🔹 Low SjO2 (<50%)  /↓CBF or ↑CMRO 2/

CAUSES

➖↓BP

➖↓PaCO2 

➖Seizures 

➖Fever 

➖↑ICP or ↓CPP

➖Vasospasm 

➖Arterial hypoxia 

🔹 High SjO2 (>80%) /↑CBF or ↓CMRO2/

CAUSES

➖Hyperemia 

➖Failure of oxygen utilization (mitochondrial failure) Hypothermia 

➖Sedation

➖Arteriovenous shunting 

➖Brainstem death

🔹 When the catheter tip lies level with the mastoid process above the lower border of the first cervical vertebra on a lateral cervical spine radiograph contamination from the extracranial circulation, will be minimal. 

🔹 Accuracy is ensured, only if the dominant jugular bulb is cannulated, but in practice the right side is usually selected

🔹 A stat sample provides a stat measure of the brain’s oxygenation and metabolic status

🔹 SjO2 can be used to guide intraoperative blood pressure and ventilatory management. SjO2 monitoring is also widely used after TBI

🔹 Relatively insensitive to regional ischemia

🔹 The complications and contraindications of SjO 2 monitoring are same as for the insertion of an internal jugular central venous line

Reference: Key Monitoring in Neuroanesthesia: Principles, Techniques, and Indications by Martin Smith, Essentials of Neurosurgical Anesthesia & Critical Care 2012 Strategies for Prevention, Early Detection, and Successful Management of Perioperative Complications

Anaesthesia for Myelomeningocele Repair; Precautions to be taken (UPDATED)

🔻Associated conditions: Hydrocephalus, Chiari II malformation, neurogenic bladder/ bowel, short trachea (Take care to avoid endobronchial intubation)hydronephrosis, malrotation of the gut, VSD, ASD, Craniofacial anomalies (Screen for these in first 24 hours after birth, before taking for surgery; may need ECHO, Renal US) Latex allergy is increased in this population Check electrolytes, RFT

🔻Goals of the surgery: Preservation of neural tissue, reconstituion of a normal intrathecal environment, complete skin closure to prevent CSF leak and meningitis. Concern: Most MMCs leak CSF from time of birth--> risk of ventriculitis--> hence closure is recommended within 48-72 hours after birth

🔻Points to ponder:

🔹Take care in prone position to avoid undue pressure over body parts..facial oedema can occur postoperatively

🔹Warmer should be arranged to avoid hypothermia; control the O.R. temperature

🔹Before induction, protect the back defect with sterile donut or rolls

🔹In case of large defects local or myocutaneous flaps may be required to close the defect adequately 

🔹Progressive hydrocephalus establishes after closure of MMC

🔹The efficacy of intrauterine meningomyelocoel repair is being explored 

🔹Anticipate lower brainstem dysfunction 

🔹Need for blood replacement is rare in straight forward cases (EBL ~25 mL)

🔹Usual duration: 1.5-3 hours

🔹If complex repair with fascial release and tight abdomen: better to ventilate for first 24 hours; otherwise on-table extubation can be done

🔹Postoperatively, child is usually nursed on stomach or side; head circumference and head USG are used to monitor for progressive HCP, which may require VP shunt

🔹Post operative complications: wound infection, CSF leak, renal failure, respiratory compromise from tight abdomen

🔹Respiratory complications : hypoventilation, sleep apnoea, bronchospasm, laryngospasm, prolonged breath holding as a result of structural derangement of  medullary respiratory control

🔹Cardiovascular complications: bradycardia, hypotension and tachycardia. Brainstem compression and coning causes most of the  cardiac complications including cardiac arrest when Chiari malformation is  associated with MMC.

🔹Delayed recovery has to be anticipated...so arrange for postop ventilation ( Respiratory centre dysfunction, due to brainstem compression, if there, will again, increase the chance of requirement for post op ventilation) 

🔹Check for swallowing, gag reflex before extubation. Extubation should be performed only when the child is awake and breathing well.

🔹Pain score 3-5