Vascular Surgery Lecture 3 – Flashcards
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What are the main 6 anticipated responses to aortic unclamping?
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Decreased arterial BP Decreased myocardial contractility Decreased CVP Decreased CO Decreased preload Decreased venous return ....when in doubt - DECREASED!
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Release of aortic cross-clamp allows for ______________ sequestered in tissues distal to the clamp to be released.
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Anaerobic metabolites
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What systemic response occurs with the release of anaerobic metabolites?
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SVR decrease, decreased venous return, decreased preload
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What is the systemic response to reactive hyperemia?
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transient vasodilation secondary to the presense of tissue hypoxia, release of adenine nucleotides
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What is anticipated to occur with fluids with AAA resection?
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Extreme loss of fluid due to: Significant third spacing Evaporative fluid loss Large blood loss
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What is the goal for fluid replacement?
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10-15 ml/kg/hr
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How are colloids helpful with fluid status?
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Help mobilize third-spaced fluid sequestration
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Where should the hematocrit be maintained with AAA resection?
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at or above 30% range
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Fluid losses greater than ________ require appropriate replacement.
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2000ml
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What product contains the majority of clotting factors?
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FFP - everything except platelets
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CAD is reported in how many patients requiring AAA resection?
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more than half
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What 5 disease processes are extremely common with AAA?
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HTN COPD DM Renal dysfunction PVD
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What is the renal blood flow reduction that occurs with infrarenal clamping?
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78%
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What ECG leads are standard for monitoring?
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lead II V5
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What vasoactive drugs should be readily available with AAA resection?
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Phenylepherine NTG SNP Dopamine
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What are three benefits of epidural combined with GETA?
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Postop analgesia early postop ambulation decreased anesthetic requirement
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What is the incidence of renal failure with infrarenal cross-clamp?
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1-2%
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What patients are at greatest risk for having renal failure post AAA repair?
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aneurysm rupture hypotensive episode suprarenal cross clamp
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What is the best prophylaxis in preventing renal dysfunction in patients undergoing AAA resection?
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adequate intravascular volume and myocardial function
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T/F: UO is a consistent predictor of postop renal dysfunction in normovolemic patients.
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FALSE - is NOT
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What is the most powerful predictor of postoperative renal dysfunction?
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preoperative renal dysfunction
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Why do most anesthetists keep patients undergoing AAA slightly hypovolemic prior to aortic cross clamp?
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Clamping increases afterload, increasing the workload of the heart Hypovolemia helps abate this response
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Where do most anesthetists keep the patient's volume status for aortic unclamping?
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slightly hypervolemic
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What are other considerations to be made with clamp of juxtarenal or suprarenal?
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Greater potential for blood loss Renal perfusion greater risk PA lines used more frequently Visceral ischemia to organs below clamp Potential for spinal cord ischemia
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What is the mortality rate for a ruptured AAA?
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94%
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What is the percent mortality with a hemodynamically stable with AAA rupture?
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50% at best
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In a patient with a hemodynamically stable AAA rupture, what are 3 main considerations?
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Same considerations but proceed expeditiously Prevent hypertension with induction Have surgical team ready to cut
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What type of induction should be performed on a hemodynamically unstable AAA rupture?
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immediate rapid sequence
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In a hemodynamically unstable AAA rupture patients, what are some of the few medication options?
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Oxygen Scopolamine Ketamine Etomidate
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What are the most common postop complications post AAA repair?
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Cardiac, respiratory, renal failure
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Where is the graft placed in an endovascular repair?
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lumen of aortic aneurysm, extending into iliac arteries
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Endovascular repair graft serves as a _______ relieving wall pressure.
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bypass
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What are the advantages of endovascular repair?
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Less invasive shorter surgery time reduced hemodynamic and metabolic stress response Decreased perioperative M&M Decreased blood loss
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What are the disadvantages of endovascular repar?
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Difficulty placing stent graft Failure to obtain adequate seal Delayed displacement of graft and leak requiring revision Unknown long term success rate (conversion to open)
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What is the percentage of anesthesia technique with endovascular repair?
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Local anesthesia Regional anesthesia general anesthesia
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What is probably more important with endovascular repair than the anesthetic technique?
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stable hemodynamics
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Where is the arterial line often placed for endovascular repair? why?
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right Left brachial artery may be accessed by surgeon
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What is a consideration with opioids in endovascular repair?
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decreased opioid requirement
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What are complications of endovascular repair?
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hemorrhage deployment failure endoleak
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How many classifications are there of an endoleak?
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5 - based on etiology
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What is the mortality with elective thoracic aneurysm and rupture?
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22% elective 54% rupture
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What is considered one of the most challenging procedures for anesthetic management?
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thoracic aortic aneurysm
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What are some causes of thoracic aortic aneurysms?
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atherosclerosis #1 Trauma #2 degenerative connective tissue disorders (marfans, ehler-danlos) Infection Congenital defects Inflammatory processes (Takayasu aortitis)
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What is the most common area for thoracic aneurysm?
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descending portion
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Thoracic dissection ________ (which direciton?) may involve the aortic valve or coronary ostia
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proximally
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Thoracic dissection ______ (which direction?) may involve the abdominal aorta or even renal and mesenteric arteries
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distally
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What is the second most common problem causing thoracic aorta dissection?
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Trauma
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False aneurysms may form distal to the left subclavian artery at the insertion of what?
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Ligamentum arteriosum
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False aneurysms often degrade in what type of fashion?
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anterograde - often deadly
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What is the incision for an ascending aortic aneurysm?
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median sternotomy requires cardiopulmonary bypass
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What is the incision for a thoracoabdominal aneurysms (TAA)?
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median sternotomy to symphysis pubis
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What is the crawford classification?
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Classification of thoracoabdominal aneurysms 4 types
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What is the worst crawford classification and what is involved?
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Type 2 - subclavian artery to distal abdominal aorta
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What is crawford classification type 1?
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begins distal to subclavian artery and extends to proximal visceral vessels
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What is crawford classification type 3?
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mid-descending thoracic aorta and varying segments of abdominal aorta
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What is crawford classification type 4?
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From mid-diaphragm down to distal aorta
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What other findings with thoracic aortic aneurysm need to be taken into consideration?
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airway deviation or compression esophageal compression with dysphagia Distortion and compression of central venous and arterial anatomy (affects afterload, preload, venous return) Hemothorax and mediastinal shift
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What is a hemothorax with mediastinal shift?
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Tension hemothorax
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T/F: THe magnitude of response to afterload is much greater with aortic cross clamp with a thoracic aortic aneurysm?
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true
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What medication is an arterial vasodilator?
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sodium nitroprusside
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What medication is a venous vasodilator?
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nitroglycerine
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What is the incidence of paraplegia after elective and ruptured thoracic aneurysm?
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20% elective 40% ruptured
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Why can paralysis occur with thoracic aneurysm repair?
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Disruption of greater radicular artery - Adamkiewicz T9-12
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What is a unique anesthetic consideration for thoracic aortic aneurysm?
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one lung ventilation
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Why is surgery for lower extremity PVD usually performed?
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bypass occlusive disease or aneurysm remove emboli repair pseudoaneurysm
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PAtients with lower extremity revascularization typically have what coexisting diseases?
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CAD CVD COPD DM Renal insufficiency
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What are three indications for elective surgery for chronic peripheral occlusive disease?
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claudication - controversial ischemic rest pain gangrene
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How are vascular reconstruction procedures classified?
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inflow - bypass of obstruction in the aortoiliac segment outflow - bypass obstructions distal to inguinal ligament
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What is the most common inflow procedure?
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aortofemoral bypass
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What is the most common outflow procedure?
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Fem-pop bypass
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The difficulty of a fem-pop and fem-tib bypass depends on what?
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site for distal anastomosis and quality of outflow vessels
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What 3 graft options may be used in lower extremity bypass?
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reversed saphenous vein saphenous vein in situ prosthetic graft
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What has a lower patency rate, prosthetic or graft?
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prosthetic
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Is an art line usually needed for an inflow or outflow procedure?
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usually inflow only
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What regional anesthetic technique is good for blocking a single extremity?
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lumbar plexus combined with sciatic nerve block
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What is a side effect of spinal or epidural anesthesia?
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reduced preload from sympathetic blockade
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What is a reason to avoid general anesthesia with lower extremity bypass surgery?
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reduction in cardiac complication - however studies are inconclusive
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Is heparin always reversed with lower extremity bypass surgery?
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nope. Bleeding problems are rare and graft occlusion is of concern
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Blood loss with lower extremity bypass surgery can go ________.
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unrecognized May not notice until you start seeing hemodynamic issues
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What are the main postoperative considerations with lower extremity bypass surgery?
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postop pain control hemodynamic monitoring
