Emergencies during neurosurgery and neuroradiology Flashcards
What level of ICP should prompt emergency treatment
> 22mmHg
What CPP should be targeted in traumatic brain injury and during neuro-surgery
CPP 60-70mmHg
Steps to reduce ICP intra-operatively in neurosurgery
- Reduce cerebral blood volume- head elevation, no neckties, neutral position to assist cerebral venous drainage
- Control PaCO2 to 4.5-5, can aim for 4 in an emergency but hypocapnia can cause vasodilation and reduced blood flow as well
- Adequate depth of anaesthesia- ensure propofol and remifentanil well titrated, consider thiopentone if needed in an emergency
- Osmotherapy- hypertonic saline 3% 3ml/kg or mannitol 0.5-1g/kg
- Steroids- only for intraoperative cerebral oedema
- CSF drainage- surgical EVD
Causes of intraoperative seizures in neurosurgery
- Cortical stimulation in epilepsy surgery
- Resection of tumours from the frontal or temporal lobes
- Acute haemorrhage or ischaemia
- Hypoglycaemia
- Electrolyte issues
- Hypocapnia
- Missed normal AEDs
Management of intraoperative seizures in neurosurgery
- A-E
- If awake patient may require airway management
- Surgeons to flood the field with ice-cold saline to suppress cortical activity
- Consider incremental boluses of propofol (0.5-1mg/kg), midazolam (2-5mg) and finally thiopentone (2-5mg/kg)
- Load with levetiracetam or phenytoin if appropriate
Management of acute occlusive vascular events in a neuroradiology procedure
- Neuroradiologists may be able to give intra-arterial drug therapy, perform MT etc
- Raise MAP to 30-40% above baseline to improve perfusion to at-risk tissue via collaterals
- Aim PaCO2 4.5-5
- May be asked to give anticoagulant/ antiplatelet drugs by neuroradiologist
Management of acute haemorrhagic vascular events in a neuroradiology procedure
- Likely to see an acute bradycardia and hypertension as ICP suddenly spikes
- Increase anaesthetic drugs
- Rapid active IV hypotensive agents such as labetalol
- Consider reversal of heparin with protamine (1mg per 100units of heparin given)
- Surgical management and opening skull
- Very occasionally giving adenosine 0.3-0.4mg/kg may be required to cause temporary flow arrest and aid clipping
Venous air embolism in neurosurgery
Subatmospheric venous pressure (as open veins are higher than the right atrium) allows the entrainment of air into the venous circulation. Higher risk in neurosurgery as the veins are often non-collapsing or sinuses allowing for larger volumes of air to be entrained.
RFx for venous air embolism in neurosurgery
- Sitting position surgery
- Posterior fossa surgery
- Large craniotomy
Pathophysiology of venous air embolism
Multiple processes:
- A large volume bolus of air sits in the right ventricular outflow tract and obstructs it causing cardiovascular collapse
- Accumulation of microemboli in the pulmonary vasculature leads to pulmonary hypertension and rt ventricular dysfunction
CFx of venous air embolism
- ECG- rt heart strain, ST and t wave changes
- Tachycardia
- Hypotension
- Raised CVP
- Reduced ETCO2
- Cough, SOB, Chest pain
- Collapse
- ABG- hypoxia and hypercapnia
Intraoperative monitoring for venous air embolism
- Clinical- ECG, ETCO2, IABP
- TOE is the gold standard
- Transthoracic doppler
Management of acute VAE in neurosurgery
Prevent further venous air entrainment
- Flood the surgical field with saline
- Apply bone wax
- Reposition the patient to head down positioning
- Manually compress the jugular veins
Reduce the size of the VAE
- Increase the FiO2 to 1.0 (eliminating N2)
- Stop the use of any inhaled N2O
- Aspirate from CVC if in place
- Commence CPR (if sys <50) as will help agitate gas
Haemodynamic support
- IV crystalloid
- Adrenaline infusion 0.05-1.0mcg/kg.min7
Positioning considerations for cardiac arrest in neurosurgical procedures
- Patient should be positioned in a way where effective CPR can be carried out. This can be prone if there is counterpressure beneath the abdomen and thorax
- If the head is in a Mayfield clamp this should be released prior to CPR and the head put in a horseshoe headrest
- The clamp/ pins should not be handled during defibrillation
Wound management considerations for cardiac arrest in neurosurgical procedures
- All instruments in the surgical site should be removed as quickly as possible
- Wounds should be protected by saline soaked swabs covered in an adhesive dressing
- In the event of ROSC the team should re-scrub, re-drape and then irrigate the wound with warmed saline
Specific ALS considerations for cardiac arrest in neurosurgery
- Initial boluses of adrenaline should be in 0.05-0.1mg aliquots until 1mg is reached and then continue as per ALS
- Reversible causes include:
- asystole from surgical retraction and vagal nerve stim
- VAE
- Haemorrhage
