Anaesthesia for vascular surgery.

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Anaesthesia for vascular surgery.

• Speaker Dr. Pragati
• Moderator Dr. Madhok.

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.co
m
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• Elective vascular surgeries are performed for
  ischemic symptoms resulting from atherosclerotic
  occlusive disease of internal carotid, aortoiliac
  and femropopliteal arteries.
  
• Emergency surgeries are done for rupture of
  aorta, cause being atherosclerotic aneurysmal
  disease or acutely thrombosed femoral trees.

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Atherosclerosis

• Risk factors DM,HTN, age,smoking, lipid
  metabolism abnormalities, high homocysteine or
  fibrinogen levels.
• PATHOGENESIS
  
• Vascular endothelial injury
  
• Increased superoxide anion generation.
• Decreased nitric oxide generation.
• Release of chemokines and adhesion molecules
  attract monocytes,which accumulate lipid and
  become foam cells.
  
• Fatty streak develops leading to irregulariy of
  intima,which attracts platelets.
  
• PDGF induce smooth muscle proliferation and
  formation of fibrous plaque.

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Medical Therapy
Drug Side Effects Recommendation
Aspirin Bleeding, ? GFR Continue until day of surgery.
Clopidogrel Bleeding, TTP Hold for 7 days before surgery.
HMG CoA reductase inhibitors (statins) LFT abnormalities, Rhabdomyolysis LFT, Continue through morning of surgery. Check CPK if myalgias
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Beta blockers Bronchospasm Hypotension Bradycardia, continue
ACE inhibitors Induction hypotension, cough Consider one half dose on day of surgery.
Diuretics Hypovolemia, electrolyte abnormalities Monitor fluid and urine status
Calcium channel blockers Hypotension with amlodipine continue
Oral hypoglycemics Hypoglycemia, Lactic acidosis with metformin Switch over to insulin, Monitor glucose.
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Neuroaxial Anaesthesia in patient receiving
thromboprophylaxis
Antiplatelet Medications Discontinue Ticlopidine 14 d Clopidogrel 7 d GP IIb/IIIa 8-48 hr in advance
Subcutaneous UFH Needle placement 4 hr after heparin Heparin 1 hr after Needle placement or Catheter removal
Intravenous UFH Needle placement / catheter removal 4 hr after discontinuing, heparinize 1 hr after neuraxial technique, delay 6 hr if traumatic.
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LMWH Neuraxial technique 12 hr after LMWH first postop dose 4-12 hr, catheters removed 10-12 hr after LMWH and 4 hr prior to next dose postpone LMWH 24 hr if traumatic.
WARFARIN INR lt 1.5 for performance of neuraxial techniques and catheter removal.
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Major Vascular Reconstruction

• High risk surgery in high risk patients
• Mortality 5 (mostly cardiac)
• An opportunity to identify and treat significant
  cardiac disease
• May be the patients first time for such
  assessment

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• The Conventional Question
• Which patients need further evaluation or
  treatment for coronary artery disease ?
  But, No evidence that CABG
  prior to non-cardiac surgery reduces mortality

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• Risk assessment methods
• Clinical
• Non-invasive tests
• Invasive tests

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• Stress ECG
• First choice in the Ambulatory patient
• More sensitive than a resting ECG
• 50 vascular patients can
  not attain adequate HR
• Assesses functional capacity
• Cost effective

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• Nuclear Perfusion Imaging
• Dipyridamole/Adenosine Thallium scanning
• Mimics exercise
• Useful when patients cannot
  exersise.
• Most common non-invasive
  test
• Relatively costly.

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• Coronary Angiogram
• The Gold Standard

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• ETTStress Mangano 1999
• ECG

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Risk reducing strategies for MI
Periop Beta-blockade 30 days before surgery and continuing. Class I
Alpha-2- agonists Clonidine 300 ?g 90 min before Sx, continue OD-3 days. Class II A
Statin Atrovastatin 20 mg OD 45 d prior and after surgery 2 wks. Class I
ACE inhibitors Decreased stroke rate, ? mortality, stabilize plaque Class II B
CCB ? Peri op cardiac events. (SVT) Class II B
NTG Suspected coronary vasopasm, treat hypertension Class III
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Perioperative myocardial infarction

• Detection 1. ECG
  2.Periop Holter monitoring.
  3.TEE.
  4.creatine kinase myocardial
  band isoenzyme.
  5.Cardiac troponins.
  MANAGEMENT mc in 1st
  24 hrs.after sx. Stable coronary syndrome occur
  with increased oxygen demand,in setting of fixed
  coronary plaques.

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• Unstable ischemic syndrome caused by rupture of
  plaque with local thrombus and vasoreactivity.
  
• Anaesthetist can control Tachycardia,hypertensio
  n/hypotension, anemia, hypothermia and shivering,
  inadequate analgesia, hypoxia.
  
• High dose narcotic anaesthetics reduce stress
  response and improve outcome.
• Epidural analgesia reduce periop MI.
• Postop sufetanil infusion reduces severity.
  
• In patients with evolving MI, intra aortic baloon
  pump can improve coronary blood flow and decrease
  afterload.

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Other medical problems.

• Hypertension increase chances of cerebral bleed
  and intraop hypotension.
• DM risk of PVD,exacerbate neurological injury,
  maintain glult150mg/dl.
• Hypercagulable states more common postop, in pts
  of PVD,deficient protien C,S antithrombin and
  HIT. Rxstop heparin, anticoagulate with
  Argatroban and 3wks of coumadin.
  
• Tobacoo abuse FEV1lt2L/sec pulmonary
  complications pneumonia, post op ventilation,
  ARDS.
  
• Renal insufficiency postop renal faliure,
  dialysis, hyperkalemia.
  

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CAROTID ENDARTERECTOMY

• Carotid a. disease atherosclerotic plaque at
  bifurcation.Thrombosis is likely to occur. 1 or 2
  TIAs/RINDsamaurosis fugax, episodes of
  clumsiness,speech problem etc. occur frequently
  before final stroke.
  
• surgical approaches
  1. carotid endarterectomy.
  
  2.percutaneous transluminal angioplasty and
  stenting.
  
• Goal for anaesthetist maintain cerebral
  perfusion.

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• PREOP EVALUATION
  H/O DM, HTN, age, tobacco abuse,
  dislipidemia,CAD. Asprin/clopidogril intake.
  
• All blood reports,cadiac tests,cerebral
  angiography size, morphology of plaque and
  associated cerebral or aortic disease.

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• MONITORING
• 
  ECG lead 2 and v5, pulseoximetry,
  etco2,temperature probe, IABP,CVP not put bcoz
  of risk of carotid puncture.
• Neurological monitoring
  1.Electrical integrity EEG,SSEP,AEP.
  2.Flow velocities and embolism detection
  transcranial doppler.
  3.Perfusion stump pressure,
  cerebral oximetry,juglar venous oxigenation.

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Intra operative concerns

• Maintain stable high normal BP to maitain
  cerebral perfusion.
• Maintain normocarbia/moderate hypocarbia
  hypercarbiasteal phenomenon
  
  
  
• use NS as IVF.
  
• Brain protection during regional ischemia
  thiopentone/ propofol/ etomidate. Hypothermia.

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• Prevention of reperfusion injury
  nimodipineCCB, steroids.
• If collateral flow is compromised or B/L carotid
  disease or complex procedure SHUNT is used.
  problems with shunt embolisation of atheroma,
  air embolism, kinking of shunt,disruption of
  artery.
• 
  
• Ensure adequate heparinisation heparin
  50-100u/kg. maintain ACTgt300sec.
• As surgeon approaches carotid sinus sudden
  bradycardia and hypotension occurs,baro-receptor
  reflex.surgeon shuld infilterate bifurcation
  with 1 lignocaine.

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Regional anaesthesia

• Sensory blockade of C2 C4 dermatomes is needed.
  Superficial and deep cervical block or
  subcutaneous infilteration of surgical field.
  
• Advantages pt. as cerebral monitor, stability of
  blood pressure, inexpensive, avoidence of GA
  induced cardiorespiratory depression.
  
• Disadvantages requires highly cooperative
  pt.,pharmacological brain protection cant be
  given,surgeons preference,difficult to protect
  airway in seizure/loc/panic.

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Postoperative management

• 1. Hyperperfusion syndrome result from increased
  CBF. Ipsilateral headache /seizures. Rxsteroids.
  
• 2.Hypertension Can lead to MI, cerebral odema,
  stroke, neck haematoma. Rx labetalol,NTG,
  esmolol.
  
• 3.Hypotension and bradycardia bcoz of
  baroreceptor exposed to high transmural pressure.
  Adjust in 12-24hrs.
  
• 4.postop respiratory insufficiency caused by
  recc. larangeal/ hypoglossal n. injury,
  defficient carotid body function , neck haematoma.

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Aortic reconstruction.

• Aneurysmal disease-ever present threat to life.
  
• Risk of rupture diameter of aneurysm.gt5cm,greate
  r risk.
• Sx.-
• Endovascular
  
  
• Open -Trans / retroperitonial
  
• approches.
  
• Expected blood loss 500 to gt2 Lts.
  

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Pathophisology of aortic occlusion.

• 1.CVS changes inc afterload,renin
  activation,catecholamine release-VC.
• Shift of blood vol. proximal to clamp inc.
  preload, inc ICP, inc. lung blood volume.
  
• Level of clamping affects- Infrarenal clamping is
  well attenuated by compliant splanchnic
  vasculature.
• 0.5mcg/kg of nitroprusside offsets the effects.
  
• Unclamping- sev. Hypotension and reperfusion
  injury Rx CaCl2 , gradual unclamping, mannitol.

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2. Renal haemodynamics.

• ARF- m/c post suprarenal clamping. Even with
  infrarenal- 70 reduction in RBF.
  Renal protection
  good hydration, mannitol, dopamine, fenoldopam.
• 3.PULMONARY COMPLICATIONS pul. Odema result
  from inc PVR and sequesteration of neutrophils.

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• 4.BOWEL ISCHEMIA hypoxic insult and bacterial
  translocation-25 mortality. Rx methyl
  prednisolone at induction is beneficial.
  
• 5.CNS/SPINAL CORD ISCHEMIA Radicular a. of
  Adamkeiewicz and hence ant. Spinal a.
  Preventive stratigies fast Sx, short clamping
  time, maintain normal cardiac function and high
  perfusion pressure.
  

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Management of aortic surgery

• Monitoring ECG,IABP, SpO2, CVP / PCWP, UO.
  
• Induce anaes. With small doses of Propofol with
  judicious amt. of Esmolol, lignocaine.
  
• For thoracic aneurysm, bronchial blockers are
  advantageous as they allow postop ventilation.
  
• Half hour before clamping reduce fluids.
  
  
• At time of clamping- VD drug/ Vol. anaes. Is
  inc./ PEEP just before clamping.

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• For thoracic level occlusion- SC perfusion is a
  concern. Accept proximal HTN, ensure adequate
  volume,maintain BP by light anaes,BT and
  endogenous vasoconstrictors.
  
• Autotransfusion devices can be used. Immediately
  before unclamping allow BP and filling pressures
  to rise high, continue volume replacement ,
  Mannitol 0.5 to 1.0 g/kg .
  
• During emergence and postop NTG/Esmolol infusions
  and maintain HRgt55bpm and BPgt110mmhg.
  

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Endovascular surgery

• Technique involves delivery of grafts PTFE/
  dacron through a catheter in Femoral a.
  
• Goals of anaesthesia
• 1. Preserve organ function
  
• 2. At time of deployment,mild hypotension and
  lack of patient movement.
  
• Preimplantation angiography is required.
  Before Dye inj. Pretreat pts. With Fluid and
  N-acetylcysteine .
  Complications of endovascular Sx are
  lower less blood loss, less ICU stay. Paraplegia
  may occur Rx induced HTN and CSF drainage. Be
  prepared for rupture, Vs. injury and embolic
  ischemia.

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Anaesthesia for emergency sx.

• For ruptured AAA- retroperitonial
  hemorrhage-pain,faintness,vomiting, pain in back/
  abdomen, shock.
  
• Prefer awake intubation/RSI with Etomidate in
  uncooperative pts.
  
• Replace volume and blood. Secure 14G catheter .
  Use fluid warmers.
  
• Once aorta is controlled,CVP and TEE probe can be
  put.
  
• If shock is resistant to dopamine/ epinephrene/
  Norepinephrine- Vasopressin should be used.
  
• Pts. Are often acidotic- Sodabicarb and increased
  ventilation should be used.
  
• Maintain temperature, hematocrit and coagulation.
  
  Primary goal is to control blood loss, maintain
  BP and then preservation of myocardial function.

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Lower extremity revascularisation

• C/C claudication,ischemic rest pain, ulceration,
  gangrene. Goals of
  anaesthetic management
  1. prevent cardiac complications.
  2. prevent hypercoagulation
• response to sx.
  3. ensure adequate perfusion.
  4. maintain graft patency.

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• Endovascular repair Angioplasty/ stenting.
  Drug eluting stents
• release Paclitaxel and prevent restenosis.
  
• Vascular reconstruction procedures inflow
  reconstruction Aortoiliac/ Aortofemoral bypass.
  
  Outflow reconstruction Fempop.
  Saphenous vein and cryopreserved umbilical v.
  show better patency than PTFE grafts.

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Anaesthetic management

• Monitoring IABP,CVP,U/O.
• Pay close attention to temparature, Oxygen
  delivery, haemodynamic homeostasis and Pain
  relief.
• Two major disadv. Of regional anaes. are risk of
  CHF autotransfusion and epidural haematoma.
  

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Regional V/S GA
Anaes.Tech Advantages Disadvantages
Regional Effective stress response blockade. Patient as monitor. Improved graft BF. No post op hypercoagulability. Postop. Analgesia Prevent chronic pain syndromes. Improved cardiopul. morbidity Time consuming. Technically difficult Inadequate for the surgery. Pt. discomfort in long cases Sympathectomy requires vol. loading. Resp. depression. Neurological sequelae. Precludes thrombolytic Rx.
General Controlled airway Hemodynamics easily controlled Reliable Patients comfort in long cases. Hyperdynamic state after surgery Fluctuations in catecholamine levels. Postop. Hypercoagulability. Greater perturbation of resp. mechanics.
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Anaesthesia for emergency peripheral vascular Sx.

• Pulseless ,cold, numb extremity, paresthesias,
  sensory/motor loss.
• Cause
  
  if embolic Fogarty embolectomy.
  If ThromboticBypass
  reconstruction.
• Risks blood loss, Inc. potassium and myoglobin,
  compartment syndrome.
• Free radical scavengers-Mannitol and N-acetyl
  cysteine should be given at time of reperfusion.

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Thank You
www.anaesthesia.co.in anaesthesia.co.in_at_gmail.co
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