Conference Lectures

Anaesthesia and Head injury in Children
Rita Pal

Introduction:
Trauma is an increasingly common cause of serious of serious morbidity and mortality around the world, and children are particularly vulnerable.TBI occurs most often in children aged 0-4 years, adolescents aged 15-19 years and elderly aged 65 years and more. Children who have severe traumatic injuries are usually pedestrians involved in road traffic accidents and head injuries occur in approximately 75% of these patients. Of those who survive severe traumatic brain injury, many are left with significant behavioral, cognitive, emotional and physical damage.
Pathophysiology:
The disproportionately larger and heavier head and weak neck muscles of children render them particularly prone to head injury after trauma. The primary cause of head injury varies with age. In infants, non-accidental injury should be considered; toddlers frequently suffer falls, whereas road traffic accidents and sports related injuries are more common in older children and adolescents.
Primary Brain injury:
Occurs in the first few milliseconds of the trauma and consists of the biomechanical effect of forces applied to the brain, which may result in brain contusion,laceration,and hematoma formation or diffuse axonal injury. Younger children are more likely to develop subdural hematomas and diffuse cerebral oedema without a skull fracture, whereas in adolescents, skull fractures, contusions and extradural hematomas are more common.
Secondary Brain injury:
Occurs in the minutes to days after the initial injury.It may be due to hypotension, raised intracranial pressure or cerebral ischaemia.Secondary brain injury is worsened by hypoxia,hypercarbia,anaemia,pyrexia,hypoglycaemia or hyperglycaemia. It may be modified by simple clinical interventions, the most important of which are avoidance of hypotension and hypoxia.

 

Types of injury:

  • Traumatic subarachnoid haemorrhage
  • Acute subdural haemorrhage
  • Epidural (extradural) haemorrhage
  • Intracerebral haemorrhage
  • Diffuse Axonal Injury

Assessment of Neurological Disability:
Rapid neurological assessment of patients with head injury may be made using the AVPU score (Alert, response to Verbal commands and Pain, Unresponsive) and modified Glasgow Coma Scale for Children:
Modified Glasgow coma score for children:

 

Score

Infant/nonverbal child

Verbal child

Eye opening

4
3
2
1

Spontaneous
To speech
To pain
None

Spontaneous
To speech
To pain
None

Verbal

5

4

3
2

1

Babbles &coos normally
Spontaneous irritable cries
Cries to pain
Moans to pain

No response

Oriented

Confused

Inappropriate words
Incomprehensible sounds
No response

Best motor response

6

5
4
3

2
1

Normal spontaneous movement
Withdraws to touch
Withdraws to pain
Abnormal flexion to pain
Extension to pain
No response

Obeys command

Localize pain
Flexion withdrawal
Abnormal flexion

Extension to pain
No response

 

Severity of head injury:


Severity of head injury

Glasgow coma scale

Mild
Moderate
Severe

13-15
9-12
</=8

 

Indication for referral for surgery:
10-20% of patients with severe traumatic brain injury have a surgically treatable condition such as extradural hematoma requiring burr hole, neurosurgical intervention may be life saving in this situation. Surgical opinion is indicated if CT scan shows an intracranial haematoma or there is clinical suspicion of an intracranial haematoma, such as focal neurological signs, depressed skull fracture,CSF leak or penetrating injury.
The anaesthesia providers may have to take care of paediatric patients on the following occations: Initial stabilization in the emergency department, providing sedation and monifor imaging, emergent surgical procedures  and intensive care management.
Therefore, they should be familiar with the principles of management of paediatric head injury as well as age-related specific anatomical and physiological aspects of trauma care.
General intensive care management:

  • Nurse the child in 300head up position with neutral head positioning
  • Maintain Spo2>95%
  • Maintain CO2 34-37.5 mm Hg
  • Maintain blood pressure in the high/ normal range
  • Avoid excessive fluid loads
  • Avoid hypotonic fluids containing dextrose. Aim for plasma sodium 145-150 mmol/l
  • Use inotropes if necessary to maintain blood pressure (noradrenalin)
  • Provide adequate sedation and analgesia
  • Maintain blood sugar in normal range
  • Consider osmotic therapies to reduce intracranial pressure such as
  • Mannitol:

10% Mannitol:0.25-0.5g/kg=2.5-0.5 ml/kg
20% Mannitol:0.25-0.5g/kg=1.25-2.5ml/kg

  • 3% Saline: Use 1-2ml/kg
  • Control seizures
  • Maintain normal temperature, treat hyperpyrexia aggressively
  • Provide adequate nutrition via a nasogastric tube

Anaesthetic Management:
Preoperative evaluation and management as outlined by AMPLE (A=Allergies,M=Medications,P=Past medical history, L=Last oral intake, Last tetanus immunization,E=Events related to injury) mnemonic should be done.In emergency,only a quick assessment of airway,breathing and circulation also to be done.
The major goals of anesthetic management of TBI are to

  • Maintain CPP
  • Treat increased ICP
  • Provide optimal surgical conditions
  • Avoid secondary insults such as hypoxemia, hyper and hypocarbia,hypo and hyperglycemia
  • Provide adequate analgesia and amnesia
  • In a child, a small intracranial bleed may result in significant loss of circulating volume.
  • Subsequent hypovolemia and hypotension may further be aggravated by preoperative infusion of mannitol and diuretic therapy
  • Cross-matched blood must be available during emergency evacuation of an extradural haematoma.
  • Precaution to prevent hypotension even for a brief period should be taken
  • Ambient temperature for infants and children to be maintained to 260c
  • Rapid-infusion devices, fluid warmers and infusion pumps should be available
  • Difficult intubation cart /provision for rapid sequence intubation should be kept ready

Anesthetic technique
Important pharmacodynamics and pharmacokinetic differences exist between intravenous and volatile anaesthetic agents. All intravenous sedative hypnotic induction agents, including barbiturates,etomidate and propofol,that are used to facilitate tracheal intubation are potent cerebral vasoconstrictors, cause coupled reduction in CBF and CMRO2,and can decrease ICP.Lidocaine is commonly used as an anaesthetic adjunct to prevent increase in ICP induced by laryngoscopy and tracheal intubation in patients, whose hemodynamic instability precludes use of large doses of sedative hypnotic agents.
All inhalational agents are cerebral vasodilators but <1 MAC of sevoflurane does not increase middle cerebral blood flow velocities compared to other agents, so sevoflurane is the preferred volatile anaesthetic agent. Nitrous oxide can increase ICP.Muscle relaxants have little effect on the tracheal intubation
Vascular access:
Peripheral intravenous or intraosseous access should be checked before medications.In traumatized child it is difficult to get a vascular access. A well-functioning iv cannula commonly in saphenous vein is used for induction and a second should be started after induction. Central venous catheters should be inserted by experienced personnel.
Fluid management:
Children can become hypovolemic from scalp injuries and isolated TBI.Isotoniccrystalloid solutions commonly used during anaesthesia and for cerebral resuscitation. Hypotonic crystalloids should be avoided. Role of colloids is controversial. The use of hydroxyethyl starch is discouraged because it may exacerbate coagulopathy.
Monitoring:
Standard ASA monitors, invasive arterial blood pressure is recommended. CVP and ICP monitoring is useful. Urine output must be monitored. Role of hypothermia in children with TBI is controversial. Arterial blood gas analysis and coagulation profile to be done hourly.
Haemodynamics (Intracranial Pressure and Blood pressure):
The presence of Cushing’s reflex and automatic dysfunction might be the only indicators of increased ICP.While SBP <5thpercentile defines hypotension,in the absence ICP monitoring and suspected increased ICP,supranormal SBP may be needed to maintain CPP. Vasopressors to be used to maintain MAP to normal level.
Maintenance of anaesthesia should follow the principles of balanced anaesthesia and provide adequate hypnosis, analgesia and muscle relaxation.
Successful extubation in patients receiving mechanical ventilation is dependent on cardiovascular stability, normal acid-base balance, presence of intact airway reflexes, ability to clear secretions  and adequate respiratory muscle strength.

 

 

Conclusion:
The unique anatomic, physiological and patho-physiological features of children  make them more susceptible to TBI.Unlike the adult with relatively poor cranial compliance the infants with open frotanelles may be able to accommodate slow and small increase in intracranial volume by expansion of the skull.However,rapid expansion of intracranial volume, small as it may be, can explain the rapid deterioration in infants following TBI.
The primary injury is irreparable other than prevention, little can be done to treat it.Hence, the focus during treatment and perioperative management of children withTBI is the prevention and treatment of secondary injuries.
The inherent problems of paediatric population poses a challenge to the anesthesiologists. To provide optimal care they must have through knowledge of neurophysiology of the developing brain and the effect of different anaesthetic agents on cerebral haemdynamics to provide optimal care.

 

References:

 

  • KavitaRaghavan,King’scollegehospital,London,Richard    Waddington,KingstonHospital,Surrey Management of paediatric traumatic brain injury –Delvered in Anaesthesia tutorial of the week 127, 30thMarch 2009.
  • Bhalla,T.et. al Perioperative Management of the Pediatric Patients with Traumatic Brain Injury.PediatricAnaesthesia ,July 2012,22(7),627-640
  • Sookplung P et al;Vassopressor Use and Effect on Blood Presser After Traumatic Brain Injury.Neurocrit Care 2011;15(1);46-54
  • Rath,G.P.,Dash H.H., Anaesthesia for neurosurgical procedure in paediatric patients. Review Article; Indian Journal of Anaesthesia, 2012,56 (5), 502-510.
  • Robert Cohn,Maroun J.Mhanna,Elie Rizkala,and Dennis M. Super: Intensive Care Unit Management of Pediatric Brain Injury , ed.Charles E. Smith,Cambridge University press Trauma Anaesthesia; pp.187-202
  • Moppett I.K.,Traumatic brain injury : assessment, resuscitation and early management; Br J Anaesth 2007;99:18-31
  • Ivashkov Y,Bhananker S.M.,Perioperative management of pediatric trauma patients;International J  of Critical Illness & Injury  Science,2012 ;2(3):143-148