Neuro Flashcards
Why sedate
A - facilitate ETT and tolerance B - comply with the vent C - reduce oxygen consumption D - comfort, augment analgesia, manage anxiety, agitation, delierium, safety control ICP
Adverse effects of sedation
Prolong MV and ICU stay Can’t assess neurological function Benzos worsen delirium Propofol causes hypotension Awareness
Benefit of a sedation hold
Reduce MV and LOS Reduces PTSD and psychological issues Decreased vasopressors Less mortality in hospita lIncrease likelihood of extubation Less need for a trachy Assess neurology
Sedation scoring systems
RASS - Richmond Agitation Sedation ScoreNegative score - sedatedPositive score - hyperroused0 - calmTarget -1
Target receptors of sedation
Agonist of inhibitory neuroreceptors —> GABA A, glycine (Propofol)Antagonise excitably receptors —> NMDAAgonist at alpha 2. —> reduces central sympathetic outflow
Dexmed
A2 agonist
Sedation and anxiolytics
Analgesic
Antihypertensive (good and bad
)No effect on resp function
Dose dependent brady and hypotension
Non inferior to propofol and midaz (PRODEX MIDEX trials)
Reduces MV and less delirium than midaz.
Classify TBI
Mild GCS 13-15Mod 8-12Severe <8
Describe primary TBI
At the time of injuryAXIAL LOADING and SHEARING FORCES —> DIFFUSE AXONAL INJURYCT - diffuse swelling, loss of grey white, and contusions (contracoup)Vascular injury —> sub/extradural, parenchymal
Secondary TBI
When cerebral oxygen consumption exceeds delivery
Due to increased CMRO2 —> seizures, pyre is
Poor delivery, low BP, hypoxia
Rising ICP impedes flow, (CPP)
Causes if secondary TBI
Cranial - seizures, rise CMRO2 Haematoma, rise ICP Hydrocephalus, rise ICP Infection, rise ICP and CMRO2
Systemic - hypoxia hypercapnia —> rise ICP Pryexia Low Na Low glucose (impaired metabolism)
Normal autoregulation of CPP
Over a range of MAP 50-150mmHg —> shifts right in chronic hypertensionAutoregulation dysrupted by TBICO2 - rise, dilates, increased ICP Low - constricts, lower ICP initially, but compromise supplyO2 - no effect except when <8 when flow rises
Methods of ICP monitoring
GCS - non invasive, cheap, quick, no expertise needed. BUT - fall in GCS is non-specific and multi factorial
CT head - loss of CSF filled spaces, loss of grey white BUT - intermittent, transfer, needs interpretation
Intraperenchymal bolt - non dominant hemisphere. Easy to insert, low risk of bleed or infection Drift - cannot be recalibrated
EVD - surgically placed in ventricle - greater risk of infection and haemorrhage Drain CSF (diagnostic or therapeutic), can be recalibrated
BTF guidelines on invasive ICP
Severe TBI (GCS <8) with abnormal CT
OR Severe TBI with normal CT brain, but 2 out of 3 of: >40 Sys BP <90 Abnormal motor score
Other circumstances to use ICP monitor in non trauma
Spontaneous ICH complicated by comaAnoxic brain injury (drowning, arrest)Hepatic enceph and cerebral oedema from fulminant failureMeningitis/Enceph
ICP waves
P1, 2, 31 - Percussion wave = arterial pressure transmit from choroid plexus to ventricle2 - Tidal wave = affected by brain compliance3 - Dicrotic wave - aortic valve closureWhen P2>P1, elevated ICP, loss of compliance
Lindberg Waves
Measures ICP over time, not morphology of one waveA - slow vasogenic waves in critical perfusion Mean ICP 50-100 lasts for 5-10 minutes. reflex dilation to a low map. Terminates with increasing MAP ALWAYS PATHOLOGICAL - SUGGEST LOW COMPLIANCEB - cycles of 30 seconds to 2 minutes. Transient increases to 20-30 above base Evidence of normal autoregulation Absence AFTER head injury is a bad signC - 4-8 minute cycles,. not clinically important
Other forms of Neuro monitor
TCD —> flow through MCA good for vasospasm in SAHSjVO2 —> reduced CBF —> increased tissue extraction —> SjVO2 falls. marker of global but not local perfusion 50% false positive for raised ICP Fibre optic catheter in IJV into jugular bulb (mastoid air cells level)NIRS local conditions onlyBrain tissue oxygenation —> adapted bolt, oxygen tissue sensor, normal oxygen tension in that tissueMicro dialysis catheter - into parenchyma via bolt. Diasylate into catheter, low molecular weight moleculres (lactate, pyruvate, glucose diffuse out) rising lactate to pyruvate ratio —> bad
Poor outcomes in TBI
Increasing agePoor motor score post resusLack of pupil reactionCT —> worsening Marshall grade oedema, midline shift, extra axial blood presence of Sub arachnid bloodHypoxia/hypotensionCo-morbids
Causes of polyuria in TBIHow to investigate
AlcoholMannitolCold diureticsHigh BMDI ?CSWSBM, temperature, alcohol level (or from Hx)Plasma and urine sodium and osmols.
Define status epilepticus
Seizure activity of more than 30 minutes
OR Recurrent seizures without return of consciousness between events
Causes of seizure
Intracranial or systemic
CranialInfection - men/encephalitisAbscessTumourStrokeEpilepsyHaemorrhage
SystemicDrugs - TCA, aminophylineAlcohol withdrawalHypoglycHyponatraemiaHypoxia
Principles of management of seizures
ABCDECheck a BM earlyFirst line - loraz 4mg (0.1mg/kg children) DiazepamSecond - Phenytoin/keppraThird - Thio/propofol/anaesthesia
Complications of prolonged seizures
CVS - tachy, hypertension —> myocardial ischaemia
Resp - Aspiration pneumonia, ARDS, pulmonary oedema
Met - High lactate, raised CK, Rhabdo, hyperthermia
Neuro - hypoxia brain injury
Effects of drugs - resp depression, arrhythmia, hypotension
Why do an EEG in status
Status needs continuous EEG, check for ongoing activity Titration drugs until BURST suppressionThen taper anaesthetic agent.
What’s the role of EEG in general in ICU
Diagnose, monitor and prognosticateDiagnose Patterns associated with conditions - seizures, enceph, CJD, Monitor Look for ongoing seizure activity Depth of sedation/awarenessPrognosticate Burst suppression, low voltage —> anoxic
Types of EEG waves
Alpha - 9-12 Hz - occipital, presents when awake, eye closed. Hypoxia if generalised
Beta - 13-20 Hz - Primary frequency ins drug induced coma
Delta - 0-4 Hz - high voltage —> metabolic enceph
Theta 4-8 children
Why admit a stroke to ICU
Airway due to low GCS
Monitoring - post thrombolysis Risk of deterioration Seizures Raised ICP Low GCSHaemodynamics - uncontrolled hypertension, arrhythmiaOther - after an op, glycaemic control, complications (sepsis/pneumonia)
Scoring systems in SAH
WFNS - based on GCS and motorFisher —> radiologicalHunt and Hess scale
WFNS SYSTEM
GRADES 1-5
1 - GCS 15 - no motor2 - 13-14 no motor3 - 13-14 with motor4 - 7-12 5 3-6
Fisher Scale
Grades 1 - 4
1 - no blood
2 - diffuse deposition without clots or layers>1mm
3 - localised clots, or blood >1mm
4 -Diffuse, or no sub arachn blood, but inter cerebral /ventricular clots
BP management in SAH
MAP to maintain CPPBUT hypertension before securing increases rebleedMaintain below 140 systLabetalol
Risks after SAH
Early rebleeding - repair
Hydrocephalus - fall in GCS, change in pupils. Insert EVD (lumbar if communicating)Vasospasm/DCI Days 4-14, prophylactic nimod 60mg 4 hourly
How to monitor for DCI
Clinical - low GCS, focal Neuro (quick, free but subjective, ?sedation)
DSA - gold standard, can intervene if vasospasm seen. Needs specialist centre, risk of arterial injury and stroke
CT angio - can explain brain parenchyma, does not need arterial access. No as sensitive as DSA.
TCD - quick, Velocity MCA>200cm/S Lindegaard index (MCA:ECA >3)EEG - expertise.
Risks for DCI
High Fisher grade Smoker Hypertension Female Coma on admission
Management of DCI
Induce hypertension —> SECURE ANEURYSM FIRSTHydration to euvolaemia (HHH is out)NimodipineIntra-arterial nimodBallon angioOther - Mg, statins, intra the cal thrombolysis…
Differential diagnosis of weakness
By anotomy —> Brain to muscleCortex - vascular event, encephalopathyStem - Pontine infarct/haemorrhage
Cord - Transvese myelitis Compression Ischaemia Infection, CMV, legionella MND PoliomyeltiitsNerves - GBS, CIP, Eaton Lambert, Ureamia. MononeuroNMJ - MG, botulism, NMBDFibre - steroid myopathy, electrolytes, CIM, disuse atrophy
Pathogens and GBS
CampylobacterMycoplasmaCMVEBSHIV
RIsks for CIM
SepsisSteroid useNMDBHyperglycaemiaElectrolyte disturbanceImmobility
Key features of delirium
Disturbance in consciousness, fluctuating, reduced ability to focus
Change in cognition/perception
Onset over of short period of time and fluctuating
Evidence (Hx/OE/Ix) of a physical precipitant
Types of delirium
HyperactiveHypoactiveMixed
Risk factors for delirium
Pre-existing and those from ICU
Pre: Increasing age known cognitive impairment Alcohol/drug/nicotine addiction Hypertension Emergency surgery or trauma
ICU High APACHE II score MV Metabolic acidosis Coma Steroids Sepsis Use of benzos
Prevent delirium
Avoid drugs that make it worse
Good sleep hygieneMaintenance of sleep wake cycleRemove lines/monitorsRe-orienate, clocks, dates etcFAMILYEARLY MOBILISATION
Reversible causes of delierium
Hypoxia Hypoglyc Uraemia Sepsis CNS infection Retention/constipation Withdrawel
Types of CNS infection
MeningitisEncephalitisBrain abscessEmpyema
CI to LP
Infection skinThrombocytopenia (<50)Coagulopathy (INR>1.5) and anticoagSuspicious of raised ICP —> CT or MRI first
Tests for an LP
Microscopy : cell count and gram stainMC&S
Biochemi - protein, glucose (paired)
Viral PCRAntigens - pneumococcus, meningococcus, GBS, H.infl Tuberculous analysis
Features of bacterial meningitis on LP
WCC - NEUTROPHIL high, normal lymphGlucose (CSF: blood ratio) <0.4Protein >1g/L
Features of viral meningitis
WCC - neuts normal, lymp highCSF:blood glucose ration >0.6 (normal)Protein 0.4-1
TB or fungal LP
WCC neuts normal, Lymph raisedGlucose CSF: blood <0.3Protein 1 - 1.5g
Red cells in the CSF
Presence of blood —> SAH OR traumatic tapProblem is working out how many WCC are from blood, and how many from inflammationPredicted CSF WCC = CSF RCC x (FBC WCC/FBC RCC)Then Actual WCC - Predicted WCC expect 1 additional white cell for 1000 RCC per mm3
Classify meningitis
By CIRCUMSTANCE or By organism
CIRC Spontaneous
Post trauma
Post opOrganism Bac, viral, TB, fungal, aseptic (autoimmune/cancer)
Risk for meningitis
Age, youngProximity - halls of residence/barracks - meningococcus Sub-Saharan Africa - Mecca Surgery or fracture - staphOtitis media/pneumonia/asplenic - pneumoccocal
Organisms by age
Neonates - E.coli, listeria, GBSChildren - neiserria, strep pneum, h.infAdults- neiserrie and strepElderly - strep, neiserira, listeriaVIRAL Entero, mumps, HSV, CMV, EBV, Variccela
Abx in meningitis
High dose ceftriaxoneAdd amoxicillin if risk of listeria (elder)STEROID - Dec 0.15mg/kg - reduced risk of hearing loss in ALL types. Mortality ben in pneumococcal
Causes of encephalitis
Largely viral HSV - most common EBV HIV Entero MeaslesRarely bacterial TBListeriaSyphillisAutoimmune - NMDA