ANESTHESIA For VASCULAR SURGERY. Mark Welliver MS, CRNA. Significant contributions from original by Gwenn Randal MSN, CRNA. Outline. Introduction Carotid endarterectomy (not covered) Peripheral vascular surgery Bypass grafting Embolectomy Abdominal aortic surgery Endovascular Surgery
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ANESTHESIA For VASCULAR SURGERY Mark Welliver MS, CRNA Significant contributions from original by Gwenn Randal MSN, CRNA
Outline • Introduction • Carotid endarterectomy (not covered) • Peripheral vascular surgery • Bypass grafting • Embolectomy • Abdominal aortic surgery • Endovascular Surgery • Thoracic aortic surgery
Vascular Surgery Patients • Coexisting diseases: • CAD 40-80% • Htn • Diabetes • Smokers • CNS; carotid disease, stroke • Renal • 50% of post op mortalities d/t MI • If the surgical site is sclerotic so are other areas
Carotid Vascular surgery • Consider carotid vascular disease coexisting • CEA Covered next spring in trauma course
Peripheral Vascular Surgery • Bypass grafting for occlusive disease or aneurysms • Upper or lower extremities • Endogenous vessels or synthetic (Gortex) • Anesthesia options: • General • Regional
Peripheral Bypass • Potential for blood loss; type and cross 2U • 2 large bore IV access (#18 minimal) • Consider central line; fluids and CVP (PA?) • Fluid warmers with blood tubing • Colloids available; Hespan, albumin • A-line for unstable or ASA 3,4 • Heating blankets (burn risk) • Serial H&H, Abgs
Peripheral Bypass • Femoral-popliteal and lower; • general, spinal, epidural • Ileo-femoral and lower; • general, spinal, epidural • Axillo-femoral; • General, regional, local
Peripheral Embolectomy • Potential for significant blood loss • Type and screen minimal • Large bore IV access • Often MAC with local • Duration?
Abdominal Aortic Surgery • Aorta below diaphragm • Bypass grafting for occlusive disease or aneurysms • Over sew or synthetic grafts (Gortex) • Anesthesia option; General alone or with epidural catheter adjunct
Abdominal Aortic Aneurysm • Common in older adults >60 (5-7%) • Appears to be a genetic link because this type of aneurysm tends to run in families. • Usually occurs in people with atherosclerosis. • Symptoms: abdominal, groin, back pain, syncope, flank mass, or paralysis • Diagnosis: routine physical find, abdominal ultrasound.
Abdominal Aortic Aneurysm Society of Vascular Surgery and the International Society for Cardiovascular Surgery have characterized abdominal aneurysms as: -suprarenal -juxtarenal -pararenal -infrarenal 90-95% of AAAs involve the infrarenal abdominal aorta.
Aneurysms True aneurysm Involves dilation of all 3 layers of the vessel wall: (outer) Tunica externa- fibrous connective tissue (middle) Tunica Media- smooth muscle/elastic tissue (inner) Tunica interna- epithelial layer, squamous cells False aneurysm Caused by disruption of 1 or more layers of the vessel wall.
Abdominal Aortic Aneurysm • <4cm--- u/s q 6 months • 4-5cm– elective repair w/low operative risk and good life expectancy. • 5-6 cm– need repair (mortality rate 0.9-5%) • 6-7 cm– threshold for rupture (mortality as high as 75%).
Overview • Large incision in the abdominal wall, just below your breastbone to top of the pubic bone • Aorta clamped • Aneurysm cut open • Plaque and clotted blood removed • Aortic graft sewn in place- functions as a conduit for blood flow
Management • Potential for blood loss; type and cross 2U • large bore IV access (#18 minimal) • Central line; fluids and CVP (PA?) • Fluid warmers with blood tubing • Colloids available; Hespan, albumin • A-line • Vasodilator gtts and vasopressors • Clamping issues… • Heating blankets (burn risk) • Serial H&H, ABGs
Endosvascular Surgery • Performed under local, mac, ga, regional • Radial a-line & IV’s in right arm • Left arm & both groins used for surgical access • Patients are discharged in 1-2 days post-op • Approved September 2000 by FDA. • Disadvantages: • Endoleaks- (failure to exclude the AAA) • Require follow-up eval’s w/serial CT scans • Demands more office visits than open
Endovascular grafting (EVR) • Catheter tip inserted through a groin artery into abdominal aorta using fluoroscopy • Catheter’s tip holds a deflated balloon. • Balloon inflated, graft opens to span the length and width of the artery. • Devices at both ends of the graft secure it to the inner wall of aorta to strengthen it and keep from rupturing • May not be available at all hospital facilities. • ADV: much less invasive
Endovascular Stent Grafts Indications • Severe COPD • Severe cardiac disease • Active infection • Medical problems that preclude operative intervention. • 1.5cm neck of aorta to pass graft between the renal arteries and the aneurysm • Anatomy/ braches/graft selection factors
Thoracic Aortic Surgery • Aneurysms • Dissection • Occlusive disease • Trauma (covered in neuro/trauma) • Coarctation (covered in Pediatrics)
Risks • Most often requires CPB • Large blood losses • Hypertension pre-op, hypotension intra-op • Myocardial ischemia • Renal ischemia • Spinal ischemia • Death
Aneurysms • Rupture-death #1 risk. >6cm 50% rupture w/in one year. • Surgical repair 2-5% mortality risk • Leaking = >50% mortality • Thoracic aneurysms: tracheal &/or bronchial compression/deviation, Laryngeal nerve compression
Thoracic Aneurysm • Ascending-between aortic valve & innominate • Arch- between innominate & l. subclavian • Descending- distal to l. subclavian
Anesthetic Management • Ascending Aorta: • Similar to cardiac surgery utilizing CPB • Consider fem-fem bypass(risk rupture w/sternotomy • Special considerations: • Long aortic cross clamp times • Large blood loss • Right radial A-line (why?)
Anesthetic Management • Aortic Arch: • Similar to cardiac surgery utilizing CPB median sternotomy • Goal- cerebral protection • Hypothermia • Thiopental infusion • Maintain flat EEG • Corticosteroids • Free radical scavengers
Anesthetic Management • Descending Aorta: • Usually without CPB • L. thoracotomy incision • One lung anesthesia • PA cath, A-line, Many large bore ivs, TEE, Cell saver, SSEP • Cross Clamping issues: • ↑SVR, myocardial ischemia, CHF, ↓CO, • Limit fluids pre-clamping • ↑anesthetic depth • Ntg, nitroprusside gtts primed & ready • Clamp Release issues: • SEVERE HYPOTENSION,↓SVR • Preload w/fluids(crystaloid,colloid) before release, vasodilators OFF • ABGs acidosis (bicarb, ↑min. vent.) • Paraplegia risk d/t thoracolumbar artery injury • Renal failure
Aortic Occlusive Disease • Incorporates Aortobifem grafting with/without peripheral thromboendarterectomy • Tx; same as above with focus on location • Rarely a localized phenomena