Abdominal Non-Aortic Pathology

These pathologies include chronic mesenteric disease, acute mesenteric ischemia, and renovascular disease.

The patient history should include any previous history of smoking, hypertension (HTN),  hyperlipidemia, and presence of other atherosclerotic diseases. In addition, it is important to assess nutritional status preoperatively, and assess for symptomatic vs. asymptomatic status to determine the need for revascularization, and for acute vs. chronic vs. sub-acute onset.  

Mesenteric occlusive disease 

In patients with mesenteric ischemia, assessment of the presence of other more common causes of abdominal pain should be included (peptic ulcer disease, cholelithiasis, diverticular disease, etc.). 

Specific elements of the history should be assessed for certain conditions: 

• Chronic Mesenteric Disease: Symptomatic patients should undergo timely revascularization for symptom relief (i.e., post-prandial pain, unexplained weight loss, food fear, etc.), to prevent bowel infarction, or to prevent further weight-loss. Asymptomatic patients may be considered for revascularization if they have the severe multivessel disease or if they require aortic surgery for other indications.
• Acute Mesenteric Ischemia (AMI): Differentiate between Acute Superior Mesenteric Artery  (SMA) embolism vs. SMA thrombosis vs. Non-Occlusive Mesenteric Ischemia (NOMI). 

Renovascular disease 

A history of early onset, resistant, accelerated, or malignant hypertension should be obtained. In  addition, inquire about unexplained renal insufficiency, ischemic nephropathy, renal atrophy, flash pulmonary edema, or cardiac perturbation syndromes.²⁷ 

Physical Examination 

Abdominal bruit may be noted in approximately 50% of patients with visceral occlusive disease,  but it is non-specific and a marker of systemic atherosclerosis.²⁸ 

A classic finding of “pain out of proportion to physical exam” is absent in about one-quarter of patients with Acute Mesenteric Ischemia (AMI). A high level of clinical suspicion is needed to establish the diagnosis.  

In patients with renovascular disease, peripheral edema can be noted, in addition to an abdominal bruit or diminished lower-extremity pulses.

Imaging 

While a detailed discussion of the imaging studies to appropriately diagnose the pathology is beyond the scope of this project, duplex ultrasound and computed tomography angiography  (CTA) are the two most commonly used imaging studies to confirm the diagnosis. While there are established ultrasound criteria for renovascular and visceral occlusive disease, this is limited by operator dependence, patient body habitus and fasting status, and a high negative predictive value.²⁹ CTA is more accurate but can be detrimental in patients with baseline renal insufficiency and can also be limited by the presence of heavy calcifications.  

Diagnostic angiogram is typically done at the time of a planned endovascular intervention.  

Medical Management and Lifestyle Changes  

Patients typically have systemic vascular disease and associated comorbidities. Accordingly,  patients undergoing invasive treatment should undergo an expedited preoperative evaluation designed to optimize their underlying medical conditions and management of their atherosclerotic risk factors. Patients with mesenteric ischemia may benefit from enteral or parenteral nutritional supplements, although this should not delay or prolong the preoperative evaluation before definitive revascularization. 

The associated comorbidities and risk factors, including smoking cessation, should be managed  optimally before revascularization, similar to patients undergoing any major vascular surgical  procedures.^{7, 30} 

The use of long-term medications can be coordinated with the patient’s primary care physician and can include the use of statins or a PCSK9 inhibitor in order to achieve optimal LDL control.  In addition, anti-platelet agents, anti-hypertensive agents, and agents for glycemic control should be prescribed, as indicated. Dual antiplatelet therapy (DAPT) should be considered if stenting is anticipated. 

Risk Stratification for Surgery 

The associated comorbidities and risk factors should be managed optimally before any revascularization for Chronic Mesenteric Ischemia (CMI), similar to patients undergoing any major vascular surgical procedures. There are well-accepted, published guidelines from most of the medical subspecialties to guide the preoperative evaluation, including those from the  American Heart Association (AHA) and the American College of Cardiology (ACC) for the optimal preoperative cardiac evaluation for patients undergoing major noncardiac surgery.^{31, 32} 

Patients with active cardiac conditions, including unstable angina, recent myocardial infarction,  significant arrhythmias, poorly compensated congestive heart failure, and/or significant valvular disease should be seen in consultation with a cardiologist and may benefit from preoperative cardiac intervention. Patients should be counseled about the importance of smoking cessation and should be treated with an antiplatelet agent and a cholesterol-lowering agent, preferentially a  statin, unless there are specific contraindications.

Patients with imaging consistent with mesenteric occlusive disease and atypical symptoms should undergo a gastrointestinal evaluation to rule out non-vascular causes of their symptoms.  

Risk Assessment  

A multidisciplinary approach to care will provide best outcomes. Team members (nurses,  physician extenders) must be familiar with the disease process to efficiently counsel and educate patients and families. Team members and specialty consultants can assist patients with risk factor modification, such as smoking cessation, maintaining glycemic control, normalizing blood pressure and lipid levels, maintaining antiplatelet therapy and fostering participation in exercise programs, thereby promoting a positive patient experience. Discharge planning should be considered at time of surgical planning.^5-9 

Acute Care Surgery consultation should be considered for patients with Acute Mesenteric  Ischemia (AMI) if bowel resection is anticipated.  

Preoperative Labs  

Recommended preoperative labs include: 

• Standard CBC, chemistry profile and coagulation profile  
• Albumin/pre-albumin for nutritional status 
• 12-lead electrocardiogram (EKG) 
• Lipid panel and HbA1c. 

In addition, if applicable, consider testing for Clopidogrel resistance, as indicated. For AMI, preoperative labs include Lactic acid, Anion gap, and D-dimers. 

It should be noted, with respect to AMI, that the following have no evidence of use yet: Serum intestinal fatty acid-binding protein (iFABP) and Urinary ileal bile acid-binding protein (I BABP). 

Preoperative Medication Adjustment  

• Medication Adjustment:  
  • Start Acetylsalicylic Acid (ASA, Aspirin) 75-100 mg/day 
  • Start high-intensity statins: Atrovastatin 40-80 mg/day or Rosuvastatin 20-40  mg/day 
  • Antibiotics: Broad spectrum coverage in cases of bowel infarction/contaminated cases. 
• Renovascular Disease: strategies to minimize nephropathy include:^{13, 14}
  • Insuring adequate IV hydration. 
  • ACE Inhibitors: If significant volume depletion is anticipated, it is suggested to hold ACE inhibitors and angiotensin receptor antagonists on the morning of surgery and restarting these agents after the procedure, once euvolemia has been achieved. 
• Diabetes Mellitus: It is suggested to hold metformin at the time of administration of contrast material among patients with an eGFR of <60 mL/min or up to 48 hours before administration of contrast material if the eGFR is <45 mL/min and restarting no sooner than 48 hours after administration of contrast material as long as renal function has remained stable. Diabetic patients who receive intermediate or long-acting insulin should receive half the scheduled dose when nil per os (NPO) in preparation for surgery.  Glycemic control should be considered per the current guidelines of the American  Diabetes Association.¹⁸ 

Anesthesia Management 

a. Optimization and Risk Assessment  

Patients who present with chronic or acute mesenteric ischemia or renovascular disease often present with multiple significant comorbidities such as poorly controlled hypertension, CAD or  COPD due to long standing smoking. These comorbidities may significantly impact the anesthesia plan.  

Patients with significant CAD and congestive heart failure may benefit from intraoperative TEE  to evaluate for regional wall motion abnormalities and left heart strain during cross clamping. 

Acute blood loss may precipitate intraoperative myocardial ischemia in patients with significant  CAD. Moderate to severe COPD predisposes patients to postoperative respiratory complications after open abdominal surgery.  

Gastric emptying may be delayed increasing the risk of aspiration upon induction of anesthesia.

b. Anesthesia Management for Open Procedures 

i) Anesthesia Techniques for Open Procedures  

Open abdominal procedures are usually performed under general endotracheal anesthesia.  Maintenance of anesthesia can be accomplished using volatile anesthetics, such as sevoflurane and desflurane, or with a propofol drip. Opioids (i.e., fentanyl or sufentanil) can be used for intraoperative pain control. Non-steroidal drugs, such as ketorolac or ibuprofen, may need to be avoided depending on the risk of kidney injury. 

Preoperative placement of an epidural catheter allows for intraoperative sparing of opioids as well as postoperative pain control.  

Most patients can be extubated in the operating room after open abdominal vascular surgery. 

If an epidural catheter could not have been placed preoperatively, bilateral TAP blocks can be  placed in the operating room prior to emerging from anesthesia to facilitate postoperative pain  management.³³ 

ii) Monitoring and Access (Open) 

Standard monitoring of SaO2, EKG, non-invasive BP, and temperature. 

• Invasive Arterial blood pressure monitoring pressure: Placement of an arterial catheter may be necessary due to cardiac comorbidities. Arterial access also allows for intraoperative blood draws for ACT measurements. 
• Central venous catheter: The use of vasoactive drugs for tight blood pressure control may require the placement of a CVL after induction of anesthesia. 
• Large bore IV access: The possibility of acute intraoperative blood loss requires large bore intravenous access for volume resuscitation. 

iii) Intraoperative Concerns (Open) 

• Patients should be well-hydrated and administered prophylactic antibiotics, typically against skin and also enteric organisms in contaminated cases. Bowel preparations should likely be avoided owing to the theoretical risk of dehydration.  
• Aortic cross clamping usually has less effects on blood pressure in occlusive aortic disease than in non-occlusive disease.  
• Renal protection during suprarenal aortic cross-clamping remains a controversial topic and thus no recommendations have been included in recent guidelines.^{3, 21} Renal cooling techniques or the use of fenoldopam or mannitol have been considered nephroprotective to some degree in smaller studies.^{22, 23} 
• In addition, intraoperative TEE may be indicated to assess left ventricular function  during aortic cross-clamping and monitor for wall motion abnormalities indicative of  myocardial ischemia, depending on the patient’s comorbidities.^{34, 35} 

Prior to release of the cross clamp, the administration of an intravenous fluid bolus (500ml  crystalloid or colloid infusion) can mitigate the effects of central hypovolemia caused by the various physiological of aortic cross clamping and the subsequent release of the clamp.  Intraoperative duplex U.S. surveillance for open procedures (mesenteric or renal) can be considered.  

Intraoperative papaverine or glucagon is not recommended yet for splanchnic vasodilatation but can be used on a case-by-case basis. 

Consider hybrid approaches—such as retrograde open mesenteric stenting (ROMS)—in patients requiring bowel resection for ischemic bowel given the contaminated field.

c. Anesthesia Management for Endovascular Procedures 

i) Anesthesia Techniques for Endovascular Procedures 

Endovascular approach can be performed under a variety of anesthesia techniques. General endotracheal anesthesia may be best-suited if holding respiration to improve imaging quality is warranted. Depending on the percutaneous or cut-down approach, endovascular procedures can be performed under local anesthesia; regional anesthesia with a nerve plexus block, such as ilioinguinal plexus block; or neuraxial anesthesia in the form of epidural or spinal anesthesia.  

The ilioinguinal nerve plexus block can be performed by the surgeon in the sterile field. 

Both the iliohypogastric and the ilioinguinal nerves originate from the nerve root of L1 and perforate the transverse abdominis muscle near the anterior part of the iliac crest. In the anterior abdominal wall, the nerves travel between the transverse abdominis and the internal oblique muscles. The nerve bundle can be visualized using ultrasounds and the injection of 10-20 ml of local anesthetic (e.g., mepivacaine, ropivacaine or bupivacaine) will anesthetize the groin area, as well as the lower portion of the abdominal wall and the upper thigh. 

Local anesthesia or regional anesthesia technique can be supplemented with mild to moderate sedation with a propofol or dexmedetomidine drip for patient comfort. 

ii) Monitoring and Access 

Standard monitoring of SaO2, EKG, non-invasive blood pressure and temperature. 

• Invasive Arterial blood pressure monitoring pressure: Placement of an arterial catheter may be necessary due to cardiac comorbidities. Arterial access also allows for intraoperative blood draws for ACT measurements. 
• Central venous catheter: The use of vasoactive drugs for tight blood pressure control may require the placement of a CVL after induction of anesthesia. 
• Large bore IV access: The possibility of acute intraoperative blood loss requires large bore intravenous access for volume resuscitation. 

d. General and Procedure-Specific Concerns 

General intraoperative concerns: Skin preparation (CHG wipe timeout for three minutes to dry),  Foley placed by trained staff, shaving performed with clippers, maintenance of normothermia.

Steps Prior to Discharge 

a. Open Procedures 

• Patients might require a stay in the intensive care unit (ICU) in order to be monitored for cardiopulmonary and gastroenterological complications. 
• Suspicion for graft failure and bowel ischemia should prompt immediate CT,  abdominal re-exploration for mesenteric ischemia, or flexible sigmoidoscopy for colonic ischemia. 
• Post-procedure ileus may be prolonged in some patients (~10%), who will require  Total Parenteral Nutrition (TPN) support.  

b. Endovascular Procedures 

• Those procedures can be done on an outpatient basis, or with overnight observation,  depending on the patient’s need for hydration and the type of access or need for access site observation.  

Steps After Discharge 

• Follow-up: Follow up call within the first week after surgery.  
• Office / Telehealth Visit: Follow-up within a month postoperative, unless indicated sooner.
• Medication:  
  • The use of long-term medications can be coordinated with the patient’s primary care provider and can include the use of statins or a PCSK9 inhibitor in order to achieve optimal LDL control. In addition, anti-platelet agents, anti-hypertensive agents, and agents for glycemic control should be prescribed, as indicated.
  • For patients treated with endovascular intervention, DAPT should be considered with ASA+Clopidogrel for 6-8 weeks, or longer if a covered stent was used. Use an alternative agent such as Ticagrelor (Brilinta) in patients who have a resistance to  Clopidogrel.  
• Imaging: Most patients receive ultrasound surveillance of the treated artery at one month. 

References