SS_NS 1.26: Endovascular thrombectomy Flashcards
:) What are the 3 main issues for endovascular thrombectomy for acute stroke?
- Time is brain (increases Rx options & chance of a good outcome)
- Remote location
- Tight BP control 140-180mmHg systolic to optimise cerebral perfusion
:) What’s the A-Z of anaesthesia considerations for endovascular thrombectomy for acute stroke?
Emergency procedure & time is brain so focussed Hx/exam, going on limited info in a pt who may have expressive/receptive dysphasia (consent issues)
All anaes procedures as rapid as possible
A: awake vs GA (no evidence-based algorithm to decide)- suggestion that pts may have better neurological outcome w GA vs MAC so long as haemodynamic stability maintained; GA if uncooperative, unable (eg. nausea/vomit) or post circulation stroke, otherwise MAC reasonable if pt can protect airway
RSI w big dose m relaxant (dysphagia in 30%). TAPE vs tie to limit pressure on carotids
Consider C-spine precautions if there was a fall/LOC ass’d w the stroke
Plan for a smooth emergence w avoidance of cough/strain/HTN, w pt awake enough for adequate neuro exam soon after extubation
Continue vasoactive medications post extubation to maintain BP goals
B: Aim SpO2 >92% (avoid hyperoxia) & PaO2 >60mmHg
Aim normocapnia
all pts should have continuous pulse ox & capnography & RR
Surgeons may request a breath hold
C: proactive, TIGHT BP control (“brain-directed haemodynamic management”) SBP>140 & <180 w DBP <105 (irrespective of if received tPA), avoid post-induction hypotension
after recanalisation discuss bp goals to reduce risk reperfusion-related complications (SBP 120-140mmHg may be reasonable)
Watch for BP spike & Brady (which may indicate ICH)
May heparinise- watch for BP spike (may indicate a dissection/haemorrhage, if so & heparinised, have protamine ready)
If ICH, keep SBP >140mmHg. if haemorrhage & heparin was given, d/w procedurals re: protamine. May require labetalol or nicardipine to keep SBP <180 & MAP <130mmHg with an ICH but shouldn’t rapidly lower- d/w surgeons.
intra-procedure ecg recommended
Art line recommended but not if delays start (otherwise slave off the radiologist’s femoral line, normal set-up with long tubing- or NIBP @ least 3-minutely)
D: Disability: pre-op neuro exam, BIS, NMT (keep 1-2 twitches, particularly important during passage of intracranial catheters)
Drugs:
Rapid-onset, short-acting sedatives/analgesics
If neurologically impaired, may require lower than normal induction doses (props/remi), give high-dose relaxant to optimise intubation
FULLY reverse (either just use sux or use roc + sugammadex)
Minimal sedative to limit confounding to postop neuro Ax
Interventionalists use contrast +++ (risk anaphylaxis, nephropathy)
Interventionalist may request heparin esp if deploy stent, may request aspirin (mix w sterile H2O)
E:
Exposure: temp probe & warming during GA but goal= normothermia (35-37degC), Rx fever w antipyretics & cooling devices
Environment: remote location issues
PERSONNEL: may be unfamiliar w anaesthetic & emergency procedures, team time-outs critically important
PATIENT:
access limited esp airway, potentially multi-comorbid requiring remote procedures
HAZARDS:
radiation
PLACE:
ergonomics (C-arm, moving bed, long extensions for venous/art access, longer tubing more dead-space)
emergency equip/procedures- unfamiliar (often different anaes equipment/draws too)
distance from OT- call early if crisis/extra hands or equip needed
lighting may be suboptimal
F: Aim for euvolemia (to minimise risk hypotensive episodes, attain adequate cerebral perfusion & to avoid cerebral oedema, accounting for the diuresis that occurs w contrast. ideally use PPV or SVV for dynamic Ax of fluid responsiveness) but lean towards RESTRICTIVE fluid (esp as unlikely IDC & interventionalists give a LOT of fluid), avoid glucose-containing fluids unless BGL <5 & avoid hypotonic fluids (risk cerebral oedema)
Consider in/out catheter @ end of procedure (may want to be assessing bl function as part of neuro)
G: monitor BGL start of case & 45-60 minutely. Rx w glucose if BGL <5, Rx w insulin infusion if BGL >14, aim 7-14; avoid glucose-containing infusions unless BGL <5
Positon/pressure areas:
limited pt access so meticulous setup vital, may be prolonged so pressure areas important
Pressure applied to vascular access site & the pt may be kept flat for up to 24hrs (cannulated leg straight/immobilised 4-6hrs)
M: pt should be on continuous BP, HR & cardiac rhythm monitoring as soon as Dx of AIS confirmed
Pain:
Minimal- LA is placed for femoral catheter insertion, the intracranial catheter manipulation can cause pain & pt agitation/movement if awake
Disposition: extubated, awake to stroke ward unless pt/surg/anaes factors impeding safe extubation (eg. significant intra-op complications, significant stroke w poor pre-op neuro function & anticipating unable to protect airway or if doesn’t meet standard extubation criteria). continuous haemodynamic monitoring should continue @ disposition.
:) What are the remote location issues for endovascular thrombectomy for acute stroke?
Access to patient:
-vigilant w setup- protect pressure areas, ensure radio-opaque items aren’t in the interventionalists’ field (need to image aortic arch, carotids, brain), ensure IV running well, backup & that it & art line are as easy as possible to access if needed (ideally on the L))
C-arm, moving bed, ergonomics:
-double extensions on lines, clear them of the C-arm w a tourniquet
-ensure enough slack on all cords
-vigilant with watching/anticipating what interventionalist doing
-positioning/ergonomics of line placement (double extensions)
High radiation:
-lead, conscious of other personnel, minimise time close to radiology source, consider that can scatter, remote monitor access while maintaining vigilance to pt/environment
:) What are some of the considerations the stroke physician & interventional radiologist will discuss re: pt suitability for clot retrieval?
-time since sign/symptom onset (within 24hrs= a candidate; pts with a large prox artery can have mechanical thrombectomy within 24hrs of last time to be @ neurologic baseline (IV tPA if <4.5hrs))
-pt premorbid status
-severity of stroke/degree of impairment caused by stroke (NIHSS score)
-how favourable the penumbra
:) What will the pt have had prior to arriving in interventional radiology?
-non-contrast brain CT (esp if within 4.5hrs for potential thrombolysis)
-Discussion btwn stroke physician & int radiologist re: clot retrieval suitability
:) Which factors may facilitate clot retrieval under sedation vs GA?
Patient factors:
-only if VERY cooperative, not agitated
-able to lie flat & still & follow commands
-NO receptive/expressive dysphasia or aphasia
-NO active cough, acute resp distress, hypoxaemia, requirement for high-flow, inability to protect airway or dysphagia (which occurs in 30%) or other risk issues w aspiration (eg. obesity, OSA), high seizure risk, nausea/active vomiting, posterior circulation/dominant cerebral hemisphere occlusion, high NIHSS (>15) or low GCS (<9)
Surgical factors:
-expected very simple, rapid procedure
:) What are benefits of clot retrieval under sedation vs GA? Cons? If sedation, what drugs?
-less vasopressor used, allows NEUROLOGICAL MONITORING throughout the procedure
-no issue w delay related to induction of GA
-less pulm morbidity
-risk of pt movement during critical components which may risk vascular injury & may slow the procedure, pt may become agitated/uncomfortable, procedure MAY be longer. Risk conversion to GA the biggest problem (delays the intervention)- if ANY concerns about the risk of conversion to GA, just do GA from outset
-GA has more control over oxygenation & ventilation
-low-dose remi or prop infusion w fentanyl @ the time of most stimulation (clot aspiration)
:) What’s the numerical goal with our tight, proactive BP control?
- maintain SBP 140-180 OR as close to possible as what they came in with
:) What may we expect the pts BP to be doing on arrival? Considerations with this?
-pt may come in hypertensive in an attempt to maintain perfusion to compromised areas of brain- it may reduce after clot removed (BP goals may need to be readjusted after reperfusion in discussion w interventionists & the stroke team)
-Procedure minimally stimulating after the laryngoscopy so will very likely need titrated high-dose vasopressor
:) What proportion are posterior strokes? Concern with this
-20-30%
-posterior strokes higher risk decreased consciousness (may be less likely able to protect airway)
:) What proportion of strokes have dysphagia symptoms?
Approx. 30%
:) Any evidence for one type of GA over another?
-no
:) Why aim SpO2 >92% for clot retrievals?
Avoid hyperoxia (ass’d with cerebral vasoconstriction)
:) What’s the pt’s ideal disposition? Considerations?
awake to stroke ward
Consider their status before the procedure, were there any complications during procedure (eg. cerebral oedema), will they have airway reflexes (even if impaired GCS)
:) Do we extubate?
-Always plan to extubate unless significant complications or significant stroke with marked neuro impairment expected lack of airway reflexes, or other standard anaesthetic reasons (eg. if hypothermic, impaired oxygenation/ventilation, if pt had an aspiration event)
:) What’s the NIHSS score?
National Institutes of Health Stroke Scale, quantifies stroke severity, 11 items scored 0-4
:) What’s the evidence for use of GA vs MAC for neurological outcome for clot retrieval for acute stroke?
GA non inferior to MAC, may be ass’d w better neurological outcome as long as haem stability maintained (improved or no worse outcome w GA shown in 3x single-centre RCTs)
eg. GOLIATH RCT- 128 pts, successful reperfusion higher in GA group, no difference in infarct growth btwn the groups but GA group had better 90-day mRS.
SIESTA RCT, 150 pts w severe AIS, better mRS @ 3/12 in the GA group
