Interview questions Flashcards
What is an EVD?
External Ventricular Drain
a soft catheter/ flexible tube that is inserted into the anterior horn of the lateral ventricle
for drainage of CSF and to monitor intracranial pressure
the catheter is connected to a drainage system outside of the body and drains via gravity. It can be opened or clamped to control the rate of drainage
What are the reasons for using an EVD?
- to reduce intracranial pressure caused by build up of CSF (possible due to a blockage)
- to divert infected CSF away from the brain & to give antibiotics directly into the CSF to treat the infection
- to drain excess fluid/blood post surgery or after a brain bleed
What symptoms would you expect if not enough CSF is being drained through the EVD?
- bulging of fontanelle in infants
- headaches
- vomiting
- irritability
- lethargy
What symptoms would you expect if too much CSF is being drained through the EVD?
- sinking of fontanelle in infants
- headaches
- pallor
- tachycardia
- irritability
What are possible EVD complications?
- Ventriculitis
- suspect if CSF glucose <50mg/dl
- higher risk if catheter has been in for a long time
- treat with Vancomycin & an anti-pseudomonal beta-lactam - Catheter occlusion
- intracranial hypotension
- blood being drained is coagulated and too thick
- ventricular wall has collapsed around the catheter - Over-drainage
- can result in subdural haemorrhage or upwards herniation
What is a subarachnoid haemorrhage?
bleeding into the subarachnoid space (between arachnoid and pia mater)
it is a life threatening condition which causes brain damage through hypoxia, raised ICP and direct cranial injury
Causes of subarachnoid haemorrhages?
Traumatic injuries such as road traffic accidents
Or spontaneous, due to:
- intracranial aneurysms
- arteriovenous malformation
- unknown
What are risk factors for spontaneous subarachnoid haemorrhages
- hypertension
- smoking
- family history
- age >50
- female sex
What are the 3 typical symptoms of subarachnoid haemorrhage?
- thunderclap headache - sudden onset severe headache reaching max intensity within seconds
- nausea & vomiting
- photophobia
What are typical clinical findings of subarachnoid haemorrhage?
- reduced consciousness - usually secondary to raised ICP
- neck stiffness - due to meningeal irritation
- +ve Kernig’s sign - inability to extend the knee when supine and hips are flexed due to pain - this is caused by irritation of the motor nerve roots which pass through the inflamed meninges
- but this is non-specific, can also be because of meningitis
What investigations can be carried out to confirm subarachnoid haemorrhage?
- plain CT head - look for blood in subarachnoid space or hydrocephalus
- CT angio - identifies aneurysms
- lumbar puncture - CSF stained yellow due to infiltration of blood from haemorrhage
Run through an ABCDE assessment of a patient with subarachnoid haemorrhage
A - ensure airway is patent because patients with reduced consciousness are at risk of occluding their airways.
May require oropharyngeal airway or intubation
B - check resp rate and SpO2 - patients may be hypoxic due to occluded airway
C - check BP and pulse - IV fluids may be needed to maintain BP
Patients may require electrolyte replacement because hyponatraemia is common in SAH
Calcium channel blockers to reduced cerebral ischaemia
D - disability - if GCS <8 anaesthetist may be required to manage airway
E - investigate whether there are any primary of secondary injuries
Management of subarachnoid haemorrhage
- EVD - to manage ICP and bleed
- obliteration of the ruptured aneurysm - via clipping or inserting fine wire
- ventricular drainage in cases with secondary hydrocephalus
Complications of subarachnoid haemorrhage
- obstructive hydrocephalus
- arterial vasospasm - cerebral arteries vasoconstrict leading to brain ischaemia
What is obstructive hydrocephalus?
occurs due to blood pooling in the ventricular system
this obstructs CSF drainage
and leads to rise in ICP
and death if untreated
diagnosed on CT as ventricles appear enlarged
EVD required
What is hydrocephalus?
active distension of the ventricular system of the brain
due to inadequate passage of CSF from its point of production within the cerebral ventricles
to its point of absorption into the systemic circulation
so the increase in CSF volume distends the ventricles and sometimes increases ICP
What are the 2 types of hydrocephalus?
- Communicating = ventricular distension in the presence of a patent ventricular system - due to conditions that reduce CSF absorption or increase CSF production
- like SAH - Obstructive = ventricular distension due to a blockage within the cerebral ventricular system
Why is it important to differentiate between communicating vs obstructive hydrocephalus before doing a lumbar puncture
Differentiating communicating and obstructive hydrocephalus is clinically useful because a lumbar puncture can be safely performed if the patient has communicating hydrocephalus.
In contrast, a lumbar puncture risks cerebral herniation if there is high intracranial pressure in a patient with obstructive hydrocephalus.
What is a VP shunt?
A ventriculoperitoneal shunt
= a medical device that connects the ventricular system of the brain with the peritoneal cavity
so CSF can drain from the ventricles into the abdomen
it runs in the subcutaneous tissue
most common indication for this is hydrocephalus
What is an extradural haematoma?
acute haemorrhage between the dura mater and inner surface of the skull
can compress local brain structures and raise ICP
if not treated can cause cerebellar herniation leading to brainstem death
most common in males between 20-30
Causes of extradural haematoma?
- commonly caused by skull trauma/ fracture - after fall, assault, sports injury
- rupture of middle meningeal artery
- arteriovenous abnormalities or bleeding disorders
How does extradural haematoma appear on CT and MRI imaging?
as a lemon shaped haematoma
What is the classical clinical presentation of an extradural haematoma?
A lucid interval following head trauma
followed by progressively decreasing level of consciousness
What is the Cushing’s reflex?
a physiological response to raise ICP in order to improve perfusion
presents with classic triad of:
- hypertension
- bradycardia
- irregular breathing pattern
How would you initially manage extradural haematoma?
- if patient is on anticoagulation, give them reversal agents to prevent further bleeding
- prophylactic antibiotics to reduce risk of intracranial infection
- anticonvulsant medical - due to increased risk of seizures - e.g. phenytoin
- IV Mannitol to decrease ICP
or Barbiturates
What is the definitive management of extradural haematoma?
Craniotomy - to evacuate the haematoma and treat the cause of bleeding (e.g. ligation of blood vessel) and to reduce ICP
What is idiopathic intracranial hypertension?
raised intracranial pressure in the absence of intracranial mass or hydrocephalus (an abnormal increase in CSF volume)
What is the ACVPU or AVPU score?
rapid method of assessing a patients level of consciousness
A = Alert (fully awake)
C = Confusion (awake but with new onset or worsening confusion)
V = Voice (patient demonstrates some form of response when you talk to them (e.g. words, grunting, moving a limb))
P = Pain (patient responds to a painful stimulus (e.g. supraorbital pressure))
U = Unresponsive (no response to any stimulus)
In patients who are not fully awake, calculate GCS score for more accurate assessment
What is NEWS score?
a tool used to assess a patients clinical status and identify early signs of deterioration based on 6 parameters
- Respiratory rate
- Oxygen saturation
- Systolic BP
- Pulse rate
- Level of consciousness
- Temperature
additional 2 points if patient is on 02 therapy
5+ = urgent
7+ = severe
What is the Glasgow Coma Scale?
used to evaluate level of consciousness in a patient
typically used in context of head trauma
Based on 3 aspects:
1.Eye-opening (4 points if they can open)
2. Verbal response (5 points if pt is orientated)
3. Motor response (6 points if pt obeys commands)
GCS 15 = fully conscious
GCS 3 = coma or dead
escalate if it drops to 8 or below
What is a tracheostomy tube?
a curved tube that is inserted into an opening made in the neck and trachea to aid breathing
Reasons you may need to have a tracheostomy include:
to help you breathe if your throat is blocked
to remove excess fluid and mucus from your lungs
to deliver oxygen from a machine called a ventilator to your lungs
What would you do if a patient has a blocked tracheostomy tube?
This is an emergency so escalate ASAP
- Check for signs of blockage: Look for signs like noisy breathing, laboured breathing, or blood in the tube.
Apply high flow oxygen to the face and tracheostomy - Suction the tube: If possible, insert a suction catheter through the tube to remove any secretions. If the catheter doesn’t pass easily, the tube is likely blocked.
- If blocked then change the inner cannula
- Ventilate the patient: If you can’t quickly proceed, you can remove the tracheostomy tube and use a manual resuscitator to ventilate the patient through their mouth and nose.
- Deflate the cuff: If the tube remains blocked, you can deflate the cuff so the patient can breathe around the tube.
- If this is not working then remove the tracheostomy tube and ensure oxygen is being given
Attempt oral intubation
What could cause a blocked tracheostomy tube?
- dried secretions
- blood clots
- a displaced over-inflated cuff
- the tracheal wall (if the tracheostomy tube is malpositioned)
