AA Aneurysm Open

== Open Abdominal Aortic Aneurysm (AAA) Repair == * **Overview:** * Open AAA repair is becoming less common due to the availability of endovascular stent placements. * The procedure is associated with significant blood loss and is generally more complex. * **Procedure Description:** * Involves repairing the AAA through a midline abdominal incision. * Most open AAA repairs have been replaced by endovascular AAA repairs. * Elective surgery is recommended for aneurysms >5 cm in diameter. * Repair methods: * Straight tube graft * Aorta to bilateral iliac graft replacement * **Symptoms:** * Usually asymptomatic, but may present with lumbar back or abdominal pain. * **Imaging:** * Methods include CT scan, MRI, basic x-ray, or angiography. * CT angiography is preferred for assessing size, location (infra- or supra-renal), and major branch status (e.g., inferior mesenteric artery). * **Causes:** * Atherosclerosis * Marfan syndrome * Ehlers-Danlos syndrome * Dissection * Congenital vasculitis * Infections, including syphilis * **Preoperative Tips:** * Keep the patient warm. * Maintain a slow heart rate (avoid tachycardia). * Avoid anemia (keep hematocrit (HCT) >25-30). * Prevent hypertension (avoid stressing the aneurysm). * **Procedure Details:** * The surgeon cross-clamps above and below the aneurysm, opens the aorta, removes the diseased section, and replaces it with a graft. * Clamps are removed with potential for large estimated blood loss (EBL). * Hemodynamic changes should be managed carefully. * **Preoperative Preparation:** * Ensure thorough cardiac workup; treat as a coronary artery disease (CAD) patient if not done. * Line and Monitoring: * Place the largest bore peripheral IVs possible (14G if possible). * Use a right internal jugular (IJ) line. * Consider a transesophageal echocardiogram (TEE) instead of a Swan-Ganz catheter for monitoring left ventricular filling status. * Have fluid warmers (1-2) and rapid transfusers or pressure bags ready. * Blood transfusion tubing (2) should be set up with normal saline (NSS). * Prepare a cell saver and warming blankets (2). * **Induction and Intubation:** * Methods to avoid hypertension with direct laryngoscopy: * Consider adding Esmolol to induction to blunt BP spikes. * Use Remifentanil (start at 0.5-1 mcg/kg/min) 8 minutes before intubation. * High narcotic induction doses can be used, similar to heart cases. * Consider using a GlideScope to reduce stimulation. * Anesthesia: * General anesthesia with endotracheal tube (ETT). * Thoracic epidural is recommended; dose or start an infusion before incision. * Rapid Sequence Induction (RSI) is commonly used. * Nasogastric (NG) tube is advisable. * Duration: 3-5 hours. * Position: Supine with arms tucked. * Estimated Blood Loss (EBL): 500-1,000 mL. * **Common Intubation Doses:** * Fentanyl: 10-20 mcg * Midazolam (Versed): 5 mg * Be prepared for rigidity with large narcotic doses. * **Pre-Induction:** * Use a priming dose of a non-depolarizing muscle relaxant or succinylcholine for RSI. * Connect fluids to the warmer as soon as possible. * Keep the patient covered; use a Bair Hugger after central line placement. * Administer a 200-500 cc fluid bolus before induction. * **Induction to Pre-Clamp Period Goals:** * Avoid hypertension to prevent aneurysm rupture. * Administer 0.5 g/kg Mannitol (usually 12.5-25 g) 30 minutes before cross-clamping. * Have Lasix available; follow the surgeon’s instructions for administration. * **Preparation for Aortic Cross-Clamping:** * Ensure nitroglycerin and/or Milrinone are available. * Monitor ionized calcium (Ca) levels. * Maintain volume and prepare to manage BP drop when unclamping. * **Complications of Aortic Cross-Clamping:** * Increased risk of renal failure: * Preexisting renal disease * Cross-clamp time >30 minutes * Hypovolemia and decreased cardiac output without partial or complete bypass * Renal protection: * Mannitol (0.5-1.0 g/kg) is crucial before clamping. * Consider Lasix, Dopamine, and Fenoldopam based on surgeon's needs. * Paraplegia: * The anterior spinal cord, supplied by a single artery, is most prone to ischemia. * Prolonged spinal cord ischemia occurs with cross-clamping times >30-45 minutes or during perioperative hypotension. * **Methods to Prevent BP Drops with Unclamping:** * Decrease anesthetic depth. * Maintain hypervolemia while clamped. * Infuse Neosynephrine before clamp removal. * Unclamp slowly as directed by the surgeon. * **Unclamping Effects:** * Reactive hyperemia due to a drop in systemic vascular resistance (SVR) from metabolites in ischemic tissue. * Lactic acid causes vasodilation. * Increased minute ventilation may help control acidosis and manage blood flow distribution. * **Late Operative and Postoperative Considerations:** * Common issues: * Facial, scalp, and airway edema. * Recommendations: * Delay extubation until edema subsides. * Elevate the patient’s head of bed (HOB) overnight. * Monitor fluid shifts postoperatively to address potential pulmonary issues. * **Spinal Cord Blood Supply:** * Supplied by: * One anterior spinal artery. * Two posterior spinal arteries. * A network of small segmental spinal arteries. * The anterior spinal cord is most susceptible to ischemia due to single arterial supply. * **Possible Complications:** * Ruptured aneurysm * Cardiac and pulmonary issues * Nerve damage causing pain or numbness in the legs * Intestinal or organ damage * Graft infection * Ureter injury * Incisional hernia * Spinal cord injury * Sexual dysfunction * Lower extremity paralysis * Death