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Anaesthesia for vascular surgery.

Anaesthesia for vascular surgery. Speaker: Dr. Pragati Moderator: Dr. Madhok. www.anaesthesia.co.in anaesthesia.co.in@gmail.com.

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Anaesthesia for vascular surgery.

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  1. Anaesthesia for vascular surgery. Speaker: Dr. Pragati Moderator: Dr. Madhok. www.anaesthesia.co.in anaesthesia.co.in@gmail.com

  2. 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.

  3. 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.

  4. Medical Therapy

  5. Neuroaxial Anaesthesia in patient receiving thromboprophylaxis

  6. 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 patient’s first time for such assessment

  7. 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

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

  9. 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

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

  11. Coronary Angiogram • The “Gold Standard”

  12. u • ETT=Stress Mangano 1999 • ECG

  13. Risk reducing strategies for MI

  14. 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.

  15. Unstable ischemic syndrome ; caused by rupture of plaque with local thrombus and vasoreactivity. • Anaesthetist can control; Tachycardia,hypertension/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.

  16. Other medical problems. • Hypertension; increase chances of cerebral bleed and intraop hypotension. • DM; risk of PVD,exacerbate neurological injury, maintain glu<150mg/dl. • Hypercagulable states; more common postop, in pts of PVD,deficient protien C,S antithrombin and HIT. Rx;stop heparin, anticoagulate with Argatroban and 3wks of coumadin. • Tobacoo abuse; FEV1<2L/sec ; pulmonary complications; pneumonia, post op ventilation, ARDS. • Renal insufficiency ;postop renal faliure, dialysis, hyperkalemia.

  17. CAROTID ENDARTERECTOMY • Carotid a. disease; atherosclerotic plaque at bifurcation.Thrombosis is likely to occur. 1 or 2 TIAs/RINDs[amaurosis 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.

  18. 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.]

  19. MONITORING: ECG [lead 2 and v5], pulseoximetry, etco2,temperature probe, IABP,[CVP not put b’coz 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.

  20. Intra operative concerns • Maintain stable high normal BP to maitain cerebral perfusion. • Maintain normocarbia/moderate hypocarbia [hypercarbia;steal phenomenon] • use NS as IVF. • Brain protection during regional ischemia; thiopentone/ propofol/ etomidate. Hypothermia.

  21. Prevention of reperfusion injury; nimodipine[CCB], steroids. • If collateral flow is compromised or B/L carotid disease or complex procedure; SHUNTis used. problems with shunt; embolisation of atheroma, air embolism, kinking of shunt,disruption of artery. • Ensure adequate heparinisation; heparin 50-100u/kg. maintain ACT>300sec. • As surgeon approaches carotid sinus; sudden bradycardia and hypotension occurs,[baro-receptor reflex].surgeon shuld infilterate bifurcation with 1% lignocaine.

  22. 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 can’t be given,surgeons preference,difficult to protect airway in seizure/loc/panic.

  23. Postoperative management • 1. Hyperperfusion syndrome; result from increased CBF. Ipsilateral headache /seizures. Rx;steroids. • 2.Hypertension; Can lead to MI, cerebral odema, stroke, neck haematoma. Rx; labetalol,NTG, esmolol. • 3.Hypotension and bradycardia; b’coz 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.

  24. Aortic reconstruction. • Aneurysmal disease-ever present threat to life. • Risk of rupture~ diameter of aneurysm.[>5cm,greater risk.] • Sx.- Endovascular Open -Trans / retroperitonial approches. • Expected blood loss; 500 to >2 Lts.

  25. 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.

  26. 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.

  27. 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.

  28. 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.

  29. 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 HR>55bpm and BP>110mmhg.

  30. 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.

  31. 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.

  32. 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.

  33. *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.

  34. 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.

  35. Regional V/S GA

  36. Anaesthesia for emergency peripheral vascular Sx. • Pulseless ,cold, numb extremity, paresthesias, sensory/motor loss. • Cause if embolic; Fogarty embolectomy. If Thrombotic;Bypass 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.

  37. Thank You www.anaesthesia.co.in anaesthesia.co.in@gmail.com

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