Anesthesia for infrainguinal revascularization

INTRODUCTION — Patients with lower extremity peripheral vascular conditions may have indications to undergo surgery to replace (eg, trauma) or exclude (eg, aneurysm) diseased vessels, or to improve blood flow in partially or completely occluded vessels. Infrainguinal revascularization may be accomplished via an open surgical, endovascular, or combined (hybrid) approach, depending on the anatomy and severity of arterial disease.

This topic will review anesthetic management of patients undergoing lower extremity revascularization procedures for arterial disease processes located at or below the level of the groin (ie, infrainguinal revascularization). Anesthetic management of thoracic aneurysm and dissection, aortoiliac aneurysm, and other indications for aortoiliac intervention and surgery are reviewed separately:

●(See "Anesthesia for endovascular aortic repair".)

●(See "Anesthesia for open abdominal aortic surgery".)

●(See "Anesthesia for open descending thoracic aortic surgery".)

GENERAL CONSIDERATIONS — Infrainguinal revascularization refers to lower extremity revascularization procedures performed at or below the level of the groin to manage a variety of arterial conditions (including complications of previous lower extremity revascularization). Revascularization efforts may be grouped according to the type of condition requiring revascularization, type of procedure, or type of access or surgical incision.

Conditions requiring infrainguinal revascularization — For patients with acute limb-threatening ischemia, early revascularization is necessary for limb salvage. For patients with chronic limb ischemia, sufficient time is typically available for preanesthetic assessment. (See 'Preanesthetic assessment' below.)

The choice of open surgical or endovascular strategy depends on the disease process, the anatomic location of arterial disease or injury, and individual patient-specific factors [1]. Decision-making for proceeding to infrainguinal revascularization is discussed in separate topic reviews:

●Peripheral artery disease (PAD)

•(See "Management of claudication due to peripheral artery disease".)

•(See "Management of chronic limb-threatening ischemia".)

●Aneurysmal disease

•(See "Femoral artery aneurysm" and "Femoral artery pseudoaneurysm following percutaneous intervention".)

•(See "Popliteal artery aneurysm" and "Surgical and endovascular repair of popliteal artery aneurysm".)

●Trauma

•(See "Severe lower extremity injury in the adult patient" and "Surgical management of severe lower extremity injury".)

●Thromboembolism

•(See "Embolism to the lower extremities" and "Thromboembolism from aortic plaque" and "Embolism from atherosclerotic plaque: Atheroembolism (cholesterol crystal embolism)".)

•(See "COVID-19: Acute limb ischemia".)

Types of procedures and access/incisions — Surgical and interventional procedures for infrainguinal revascularization or management of complications may include endovascular procedures, focal procedures, and open surgical bypass. Depending on the nature and extent of revascularization, the approach to may involve only percutaneous access, a focal cutdown procedure, longer surgical incisions to access the arteries or to harvest veins, or a combination of these (eg, hybrid revascularization).

●Endovascular procedures – Endovascular procedures use contrast arteriography to define the anatomy and extent of vessel occlusion. Interventions may include angioplasty with or without stenting/stent-grafting, and possibly thrombolytic agents for thrombolysis either as a primary procedure (eg, embolism) or as a rescue procedure to manage complications (eg, thrombosed stent). (See "Endovascular techniques for lower extremity revascularization" and "Intra-arterial thrombolytic therapy for the management of acute limb ischemia".)

Endovascular procedures are performed via percutaneous access, typically at the level of the groin, but approaches can also include popliteal or pedal access. On occasion, a cutdown procedure may be required to gain access.

●Focal open surgical procedures – Examples of focal procedures include endarterectomy of a stenotic vessel (eg, common femoral endarterectomy) or repair of a discrete arterial injury (eg, debridement and primary repair). Common femoral endarterectomy may be done as a standalone revascularization, but more typically it is an adjunctive procedure for surgical bypass or endovascular revascularization. (See "Approach to revascularization for claudication due to peripheral artery disease", section on 'Common femoral artery' and "Surgical management of severe lower extremity injury", section on 'Revascularization'.)

Focal arterial procedures typically involve open surgical exposure directly over the vessel of interest, most typically the common femoral artery to perform embolectomy, or for endarterectomy.

●Open surgical bypass – For open surgical bypass grafting, the extent of surgical incisions varies depending on the nature of the proposed bypass and type of conduit used (eg, autogenous venous conduit, prosthetic conduit). (See "Lower extremity surgical bypass techniques".)

Arterial access for infrainguinal bypass procedures involves proximal and distal incisions in the extremity at the sites of arterial inflow and outflow to and from the graft, respectively. Typical locations include the groin, the distal thigh overlying the superficial femoral artery at the adductor canal, the medial proximal leg to access the popliteal or proximal tibial vessels, distally at the medial ankle (posterior tibial artery), or on the dorsal foot (anterior tibial artery). When prosthetic graft is used, the graft is tunnelled subcutaneously between these incisions.

Additional incisions are necessary to harvest vein for autogenous grafting. Vein harvesting for infrainguinal bypass is ideally from the ipsilateral great saphenous vein if adequate in diameter. Alternatively, other veins must be harvested, such as the contralateral great saphenous vein, the small saphenous vein(s), and at times, upper extremity vein(s) (eg, cephalic, basilic). Although these incisions can be extensive, they are limited to the subcutaneous tissues.

Management of complications related to lower extremity revascularization might include evacuation of an incisional hematoma, re-do lower extremity bypass grafting (eg, failed bypass, stent/stent-graft occlusion), or excision of graft material related to infection (eg, bypass, stent-graft). At times, amputation may be necessary to manage a failed bypass, or as a primary option for patients with chronic limb-threatening ischemia who do not have any revascularization options. (See "Lower extremity surgical bypass techniques", section on 'Complications' and "Endovascular techniques for lower extremity revascularization", section on 'Complications and management' and "Access-related complications of percutaneous access for diagnostic or interventional procedures".)

PREANESTHETIC ASSESSMENT — Comorbid conditions that may impact overall perioperative risk are common in patients with peripheral vascular conditions (eg, peripheral artery disease [PAD], aneurysm, thromboembolism). Goals of the preanesthetic consultation for elective procedures include working with the patient's primary care and/or cardiology teams to identify and manage treatable issues to ensure optimal preoperative condition. Particular attention is directed to management of cardiovascular disease, chronic obstructive pulmonary disease (COPD), diabetes mellitus (DM), and renal insufficiency that may be exacerbated by the exposure to contrast necessary for endovascular procedures.

Cardiovascular risk — Patients presenting for infrainguinal revascularization typically have a high incidence of coronary artery disease (CAD), cardiac valvular disease, hypertension, and cerebrovascular disease, and postoperative myocardial injury is common [2,3]. Severe asymptomatic CAD was present in 55 percent of patients with lower extremity PAD in one study [4]. Patients with vascular trauma are younger with few cardiovascular comorbidities; however, extremity vascular trauma is associated with other injuries that may increase anesthetic and perioperative risk.

In a 2018 prospective cohort study of more than 15,000 vascular surgery patients, myocardial injury after noncardiac surgery (MINS) was defined as elevation of fourth-generation troponin T ≥0.03 ng/mL [2]. Patients with MINS had significantly higher 30 day postoperative mortality (12.5 percent) compared with those without MINS (1.5 percent). Nearly three-quarters of the vascular surgical patients with MINS were asymptomatic in the postoperative period, with no overt evidence of myocardial ischemia [2]. Furthermore, in a retrospective study that included more than 16,000 patients undergoing vascular procedures, postoperative troponin elevation predicted a 26 percent reduction in survival five years after surgery, while overt postoperative myocardial infarction predicted a 55 percent reduction in survival after five years [3].

Preoperative evaluation of cardiac risk is discussed in separate topics, including perioperative management of chronically administered medications such as beta blockers, angiotensin converting enzyme inhibitors, clonidine, statins, and aspirin or other antiplatelet agents. (See "Evaluation of cardiac risk prior to noncardiac surgery" and "Management of cardiac risk for noncardiac surgery".)

Perioperative anesthetic management of patients with ischemic heart disease and/or hypertension is discussed separately. (See "Anesthesia for noncardiac surgery in patients with ischemic heart disease" and "Anesthesia for patients with hypertension".)

Chronic kidney disease — Chronic kidney disease is common among patients with lower extremity PAD requiring revascularization.

Patients with chronic kidney disease are at increased risk for developing contrast-induced nephropathy (CIN). A creatinine level should be obtained in the immediate preoperative period. If the value is elevated compared with the patient's baseline, consultation with a nephrologist is recommended. (See "Prevention of contrast-associated acute kidney injury related to angiography", section on 'Identifying patients at risk'.)

If angiography with contrast is to be performed, the patient should be adequately hydrated to reduce the risk of CIN.

●For outpatients (eg, endovascular revascularization for lifestyle limiting claudication), intravenous isotonic saline 3 mL/kg is typically administered over one hour before the planned procedure, then 1 to 1.5 mL/kg/hour is administered during and for four to six hours after the procedure.

●For inpatients, 1 mL/kg/hour of isotonic saline is administered for 6 to 12 hours before and during the procedure, then for 6 to 12 hours after the procedure. Such protocols for fluid administration as well as other preventive measures to minimize risk for CIN are discussed separately. The use of a balanced salt solution rather than saline is generally advocated for patients at risk of acute kidney injury (AKI). However, this recommendation has not been studied in the context of CIN [5]. (See "Prevention of contrast-associated acute kidney injury related to angiography", section on 'Fluid administration'.)

In a meta-analysis that included 15 studies and more than 11,000 patients undergoing endovascular procedures, the incidence of CIN ranged from 0 to 45 percent [6]. In a large registry study of more than 13,000 patients undergoing endovascular procedures, a 3 percent incidence of CIN was noted; 6.5 percent of these patients required dialysis [7]. Patients who developed CIN had increased risk for in-hospital mortality (adjusted odds ratio [OR] 18.1, 95% CI 10.7-30.6), as well as other morbidity such as myocardial infarction, stroke or transient ischemic attack, increased blood transfusions, and longer durations of hospital stay. Predictors of CIN included case acuity (urgent or emergency surgery); extremes of body mass index (>30 or <18); low preprocedure creatinine clearance <30 mL/minute; anemia; patient history of DM, heart failure, or COPD; as well as a contrast dose exceeding three times the calculated creatinine clearance [7].

Other medical comorbidities — Other common comorbidities in patients with arterial disease requiring infrainguinal revascularization include:

●Diabetes mellitus – Approximately one-third of patients with PAD have comorbid DM. Risk factor management and glycemic control are important for reducing complications. (See "Overview of peripheral artery disease in patients with diabetes mellitus" and "Perioperative management of blood glucose in adults with diabetes mellitus".)

●Chronic obstructive pulmonary disease – COPD is common and usually associated with chronic tobacco use among patients with PAD requiring infrainguinal revascularization. Counseling regarding preoperative smoking cessation is particularly important in patients with PAD to improve perioperative outcomes, including risk of adverse cardiovascular events, pulmonary complications, and limb loss. Although optimal timing is at least eight weeks prior to surgery, cessation for as little as two days may have some benefits for those requiring urgent revascularization [8]. (See "Evaluation of perioperative pulmonary risk", section on 'Smoking' and "Strategies to reduce postoperative pulmonary complications in adults", section on 'Smoking cessation'.)

Planned surgical technique — Preoperative communication between the surgical and anesthesia teams is necessary to understand the planned surgical procedure and potential incisions. This may affect choice of anesthetic technique (eg, type of access, extent and location of surgical incision[s]). (See 'General considerations' above and 'Choice of anesthetic technique' below and "Patient safety in the operating room", section on 'Timeouts, briefing, and debriefing'.)

CHOICE OF ANESTHETIC TECHNIQUE — Local, regional, neuraxial, and general anesthesia techniques have been used for endovascular or open infrainguinal revascularization. The selection of a particular technique depends on procedure-specific factors (eg, anticipated duration of the procedure, anticipated incisions), patient-specific factors (eg, anticoagulation, patient preference), and surgeon preference [9]. (See "Overview of anesthesia", section on 'Types of anesthesia'.)

In some cases when local or regional anesthesia has been selected, conversion to general anesthesia may be necessary as the surgical procedure progresses. Indications for conversion to general anesthesia include patient inability to lie still (eg, severe agitation), patient request, or surgery-related factors (eg, procedure will take longer than initially anticipated).

Occasionally, a combined technique that includes both a neuraxial anesthetic and general anesthesia is selected at the beginning of the procedure to provide optimal intraoperative conditions as well as excellent multimodal management of postoperative pain (ie, general anesthesia plus epidural or peripheral nerve block for supplemental analgesia) in selected patients.

Endovascular revascularization — For most patients undergoing endovascular infrainguinal revascularization, only local anesthesia with monitored anesthesia care (MAC) is needed. Endovascular revascularization typically uses percutaneous access to perform angioplasty, place stents or stent-grafts at an area of stenosis/occlusion, or to administer thrombolytic agents. Local anesthesia is administered prior to needle access by the surgeon. Difficult access or hybrid procedures may necessitate surgical cutdown to access the vessel, which is often amenable to local anesthesia administered by the surgeon, or a peripheral nerve block administered by the anesthesiologist [10]. Since anticoagulation is required during lower extremity endovascular procedures, a neuraxial technique is rarely selected. (See 'Types of procedures and access/incisions' above and "Endovascular techniques for lower extremity revascularization".)

Sedative and/or analgesic agents can be minimized or even avoided during MAC for endovascular revascularization, provided the patient can lie still. As an example, 25 to 50 mcg boluses of fentanyl may be administered to patients with discomfort during angioplasty. (See "Monitored anesthesia care in adults", section on 'Drugs used for sedation and analgesia for monitored anesthesia care'.)

For patients with chronic-limb threatening ischemia and severe rest pain, combined femoral and sciatic nerve blocks can be used to treat the pain may facilitate absence of movement and tolerance of complex endovascular revascularization procedures [11].

General anesthesia is a reasonable alternative for patients who are poor candidates for local anesthesia with MAC. Examples include those who are unable to tolerate supine positioning (eg, due to severe symptomatic COPD, heart failure, chronic back pain) or lie still for the duration of the procedure due to pain or inability to cooperate or communicate. The surgeon's preferences and patient requests (eg, the desire to avoid any awareness experiences associated with conscious sedation) also influence selection of anesthetic technique. (See "Monitored anesthesia care in adults", section on 'Appropriateness of monitored anesthesia care' and "Accidental awareness during general anesthesia", section on 'Management of patient expectations'.)

Open surgical revascularization — For patients undergoing open infrainguinal revascularization, we suggest a neuraxial technique (spinal, epidural) when there are no contraindications [12-16]. There is no guidance regarding the specific choice of neuraxial technique. The decision to proceed with spinal rather than epidural or combined spinal-epidural should be made based on the anticipated duration of the surgical procedure and the anticipated benefit of an epidural for postoperative pain control. In general, a T10 level is adequate.

Due to procedure- and patient-related factors, general anesthesia rather than a neuraxial technique is often necessary or desirable. In some cases, a combined technique (ie, general anesthesia plus epidural or peripheral nerve block for supplemental analgesia) will optimize intraoperative conditions as well as excellent multimodal management of postoperative pain. (See 'Poor candidates for neuraxial techniques' below and "Overview of neuraxial anesthesia", section on 'Preoperative evaluation' and "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication".)

Open infrainguinal revascularization techniques vary in complexity, ranging from procedures that require a single incision in the groin such as femoral embolectomy, to those that require more extensive incisions along the length of the extremity (see 'Types of procedures and access/incisions' above). A neuraxial anesthetic technique (eg, spinal or epidural) is often selected for femoral endarterectomy, femoral-to-popliteal bypass, or hybrid procedures [12,13].

In a 2013 meta-analysis that included four trials [14], the pooled incidence of pneumonia from two of the trials (201 patients) was significantly reduced for neuraxial compared with general anesthesia (odds ratio [OR] 0.37, 95% CI 0.15-0.89) [17,18]; however, other outcomes (eg, mortality, myocardial infarction, lower limb amputation) were similar in the four included trials, and in other trials [17-22].

Large database studies comparing anesthetic outcomes after lower extremity revascularization have reported inconsistent results, which may be due to selection bias stemming from the inability to control for factors influencing the clinician's technique selection that may not have been recorded in the databases, such as perioperative use of antithrombotic agents, anticipated duration of surgery, intraoperative need to perform an upper extremity vein harvest, as well as patient or surgeon preferences [15,16,21,23-26]. Furthermore, studies often don't differentiate between patients receiving spinal anesthesia, epidural anesthesia, or peripheral nerve block, which have different physiologic effects [27]. It is notable that retrospective database studies show that under real-world conditions, general anesthesia is used more often for infrainguinal revascularization [15,16].

●A review of the Danish Vascular Registry used propensity score-matching to compare outcomes of general anesthesia versus regional anesthesia (6267 in each group); regional anesthesia was defined as epidural, spinal, or peripheral nerve block [27]. The incidence of surgical (eg, wound infection, reoperation) and general complications (eg, myocardial infarction, stroke) was significantly higher in the general anesthesia compared with the regional anesthesia group (3.8 versus 2.5 percent, 6.5 versus 4.2 percent, respectively). Perioperative (30 day) mortality was also significantly higher in the general anesthesia group (3.1 versus 2.4 percent). There was small, but significant differences with respect to surgical time, estimated blood loss and indication for surgery.

●A 2013 review of infrainguinal bypass from the National Surgical Quality Improvement Program (NSQIP) in the United States noted that 4768 patients received general anesthesia, while only 694 patients received regional anesthesia (either neuraxial anesthesia or a regional block) [16]. There was no association between anesthetic type and outcomes. General anesthesia was more likely for patients receiving anticoagulants, while a regional anesthesia was more likely for those with COPD. An earlier report from NSQIP from 2006 reported similar rates of perioperative (30 day) mortality for general anesthesia compared with neuraxial techniques (spinal or epidural); however, general anesthesia was associated with increased risk of pneumonia (OR 2.2, 95% CI 1.1- 4.4), postoperative myocardial infarction (OR 1.8, 95% CI 1.32-2.48), need for return to the operating room (OR 1.17, 95% CI 1.05-1.31), and graft failure (OR 1.43, 95% CI 1.16-1.77) [15]. Other observational studies have not found associations between graft patency or amputation rates in patients receiving general anesthesia compared with other types of anesthesia [16,24,25].

●A 2019 review of the Vascular Quality Initiative (VQI) database identified 16,052 patients chronic limb-threatening ischemia undergoing infrainguinal bypass from 2011 to 2016, but only 572 (3.2 percent) patients received neuraxial anesthesia (epidural or spinal) [28]. One-third of participating centers did not report using neuraxial anesthesia. While perioperative mortality was similar, neuraxial anesthesia was associated with a shorter length of stay and a lower incidence of postoperative heart failure. Patients who received neuraxial anesthesia were older, more likely to have COPD, and were undergoing non-emergency procedures.

●Lastly, a 2020 review of nearly 21,000 patients undergoing a first infrainguinal revascularization from hospitals in Ontario, Canada noted that the percentage of patients receiving neuraxial anesthesia varied widely ranging from <1 percent to 91 percent in different institutions [26].

Poor candidates for neuraxial techniques — Although a neuraxial technique is desirable, most open lower extremity infrainguinal revascularization procedures are performed using general anesthesia. In a review of the NSQIP database, 694 of 5462 patients (13 percent) received regional anesthesia (either neuraxial anesthesia or a regional block) [16]. Those receiving general anesthesia were more likely to be receiving anticoagulants, while those receiving a regional anesthetic technique had a higher prevalence of COPD. In a later NSQIP review, only 3.5 percent undergoing lower extremity bypass received neuraxial anesthesia [28]. Older age, COPD, and surgical urgency were associated with selection of a regional anesthetic technique.

Potential reasons for choosing general anesthesia rather than neuraxial anesthesia include:

●Concerns regarding antithrombotic therapy – Patients undergoing infrainguinal revascularization for peripheral artery disease (PAD), thromboembolism, aneurysmal disease, and those with vascular stents are often receiving antiplatelet, antithrombotic, or thrombolytic therapy for the treatment of their vascular disease [16,29]. Whether to interrupt antiplatelet therapy or anticoagulation (acute or chronic) is determined by weighing the risk of complications associated with temporary cessation of antithrombotic medications versus the potential risk of surgical bleeding while anticoagulated and/or the desire to avoid general anesthesia.

•Antiplatelet therapy – Patients with chronic disease will typically be receiving either aspirin alone or dual antiplatelet therapy with aspirin and clopidogrel. (See "Overview of lower extremity peripheral artery disease", section on 'Antithrombotic therapy'.)

Data are scant regarding the safety of neuraxial anesthesia if antiplatelet therapy continued throughout the perioperative period [30]. In one retrospective study, none of the 306 patients who underwent elective lower extremity vascular surgery under continuous epidural anesthesia without withholding clopidogrel (except on the day of surgery) had suspected spinal-epidural hematoma (SEH) or developed any new neurologic symptoms [31]. Similarly, a report of 17 patients with PAD who had above- or below-knee amputations under spinal anesthesia after stopping clopidogrel for <24 hours noted that none developed SEH [32].

•Anticoagulation/thrombolytic therapy that will not be interrupted – Patients who require continuous perioperative anticoagulation or thrombolytic therapy are not candidates for neuraxial techniques. Patients with acute arterial thromboembolism are typically treated using a heparin infusion or thrombolytic agents in the perioperative period. If temporary interruption is not possible, the use of neuraxial anesthesia is precluded. (See "Perioperative management of patients receiving anticoagulants", section on 'Deciding whether to interrupt anticoagulation' and "Embolism to the lower extremities", section on 'Anticoagulation'.)

A detailed discussion of the decision-making process for use of neuraxial anesthesia in patients who are receiving medications that interfere with coagulation or platelet function is reviewed separately. Considerations also include the appropriate timing for performance of neuraxial procedures when antiplatelet or antithrombotic therapy will be interrupted, and also for removal of epidural catheters to minimize the risk of SEH [33]. (See "Perioperative management of patients receiving anticoagulants", section on 'Deciding whether to interrupt anticoagulation' and "Perioperative management of patients receiving anticoagulants", section on 'Neuraxial anesthesia' and "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication".)

●Infection – Patients undergoing lower extremity procedures can require surgery to manage infective complications (eg, infected pseudoaneurysm, graft infection, foot infection). Neuraxial anesthesia is generally avoided in those with systemic infection [34]. (See "Overview of neuraxial anesthesia", section on 'Infection'.)

●Anticipated prolonged duration of the procedure – Complex infrainguinal revascularization procedures are likely to have a prolonged duration. Some patients will not tolerate supine positioning or cannot lie still for the duration of the procedure. (See 'Endovascular revascularization' above.)

●Patient factors – These include the inability to cooperative or communicate, or the desire to avoid any awareness experiences associated with conscious sedation. These considerations can influence selection of anesthetic technique. (See "Accidental awareness during general anesthesia", section on 'Management of patient expectations'.)

●Surgeon preference – The surgeon may indicate a preference based on patient characteristics, possible need for extending the incision or performing additional procedures, or other technical factors.

INTRAOPERATIVE ANESTHETIC MANAGEMENT

Intravascular access and invasive monitoring — In the absence of severe cardiac comorbidity, standard American Society of Anesthesiologists monitors are typically sufficient for elective endovascular and open revascularization procedures. (See "Basic patient monitoring during anesthesia", section on 'Standards for monitoring during anesthesia'.)

Insertion of an intra-arterial catheter is reasonable for blood pressure monitoring in patients with significant cardiac dysfunction and those undergoing complex open procedures that may be of prolonged duration. Ultrasound is typically used to identify and guide catheter placement for patients in whom peripheral vessel palpation is difficult. Although peripheral arterial disease is a risk factor for catheter thrombosis, permanent injury is rare. (See "Intra-arterial catheterization for invasive monitoring: Indications, insertion techniques, and interpretation".)

Large bore volume access is typically unnecessary for patients undergoing endovascular procedures or uncomplicated open infrainguinal revascularization procedures. Central venous catheter (CVC) access may be used in patients with inadequate peripheral access and those likely to require intraoperative administration of inotropes or vasopressors. If a CVC is inserted, central venous pressure (CVP) may be monitored to provide supplemental data regarding intraoperative fluid management. (See "Central venous access in adults: General principles" and "Intraoperative fluid management", section on 'Traditional static parameters'.)

Anticoagulation administration and monitoring — When the surgeon has determined that anticoagulation will be used prior to vascular clamping, intravenous unfractionated heparin is administered and monitored by the anesthesiologist via point-of-care activated clotting time (ACT) testing.

Open surgical revascularization — During open surgical infrainguinal revascularization, intravenous unfractionated heparin is typically administered prior to placing a clamp across a peripheral artery to prevent thrombosis in the distal artery during the ensuing period of low or no flow. (See "Lower extremity surgical bypass techniques", section on 'Antithrombotic therapy'.)

Intraoperative unfractionated heparin may be administered one or more hours after the insertion of an epidural catheter without significant increased risk of spinal epidural hematoma, as discussed separately. (See "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication", section on 'Intravenous UFH'.)

Since there are few data regarding optimal dosing strategies for heparin, institutional practices vary with respect to monitoring of anticoagulant effect, timing of readministration, and decisions to reverse with protamine. We use a heparin dosing strategy that is guided by point-of-care ACT values, typically with a target ACT of 200 to 250 seconds. Others target an ACT that is approximately twice the patient's baseline value [35,36]. However, there are few data supporting specific ACT targets for infrainguinal revascularization procedures [37]. Some institutions obtain intermittent activated partial thromboplastin time levels, with measurements performed in the laboratory.

In some institutions, a fixed-dose strategy is used, with periodic heparin boluses over the course of the procedure. Guidelines from the American College of Chest Physicians recommend administration of 100 to 150 units/kg of heparin prior to clamp placement with re-administration of 50 units/kg every 45 minutes while the arterial clamps remain in place [38,39]. However, fixed-dose heparin administration doesn't account for variability in heparin metabolism, challenges of weight-based dosing in patients with obesity or cachexia, or the possibility of heparin resistance in some patients [35].

Some surgeons inject heparin directly into the cross-clamped vessels, either in addition to, or as a substitute for systemic anticoagulation (eg, limited procedure, contraindications to anticoagulation). In such cases, heparin administration and dosing of its reversal agent are based on the ACT value following reperfusion.

Few data exist regarding appropriate indications and dose for reversal of heparin anticoagulation after infrainguinal revascularization [40]. If the surgeon decides to administer protamine sulfate, dosing is typically based on estimates of the remaining heparin in the plasma (eg, 1 mg protamine per 100 units of estimated remaining heparin). Considerations for estimates of remaining heparin include the number of heparin doses administered, half-life of heparin (approximately 45 minutes), and time since the last dose of heparin. (See "Heparin and LMW heparin: Dosing and adverse effects", section on 'Reversal'.)

Endovascular revascularization — Anticoagulation is required during endovascular procedures; a target ACT of 180 to 240 seconds is typically selected [41]. Most surgeons elect to withhold protamine administration after endovascular procedures. (See "Endovascular techniques for lower extremity revascularization", section on 'Anticoagulation'.)

Few data exist to guide heparin dosing and reversal in these procedures. One retrospective study of more than 1200 patients undergoing endovascular interventions noted that a total heparin dose ≥60 units/kg or a peak ACT ≥250 seconds predicted reduced hemoglobin levels and higher transfusion rates [42].

Alternatives to unfractionated heparin for anticoagulation during endovascular procedures have been described (eg, low molecular weight heparin, direct thrombin inhibitors) [43,44]. Specific alternatives for patients with heparin-induced thrombocytopenia are discussed separately. (See "Management of heparin-induced thrombocytopenia (HIT) during cardiac or vascular surgery".)

Hemodynamic management — Generally, we attempt to maintain blood pressure within 20 percent of the patient's baseline and keep mean arterial pressure >65 mmHg (see "Hemodynamic management during anesthesia in adults", section on 'Blood pressure targets'). Most patients with PAD also have hypertension. Although untreated hypotension may result in insufficient myocardial, cerebral, and renal perfusion in such patients, severe hypertension may also result in myocardial ischemia as well as increased surgical bleeding. (See "Anesthesia for patients with hypertension".)

Similar to anesthetic management of patients undergoing endovascular or open aortic surgery, vasoactive drugs should be readily available to rapidly treat hypotension, hypertension, tachycardia, bradycardia, or arrhythmias. These include sympathomimetics, vasoconstrictors, vasodilators, adrenergic antagonists, and antiarrhythmic agents (table 1 and table 2). (See "Anesthesia for open abdominal aortic surgery", section on 'Vasoactive drugs' and "Anesthesia for endovascular aortic repair", section on 'Hemodynamic management'.)

POSTOPERATIVE ANESTHETIC AND PAIN MANAGEMENT — Postoperative care in the post-anesthesia care unit is typically adequate. Intensive care unit admission may be necessary for patients who have undergone complex revascularization procedures with significant blood loss or those who are hemodynamically unstable [45].

Pain management techniques are tailored to the extent of the procedure. General recommendations for management of acute postoperative pain after surgical procedures are reviewed separately. (See "Approach to the management of acute pain in adults".)

Most patients experience only mild-to-moderate pain due to superficial incision(s) and are able to ambulate as early as the first postoperative day. Administration of systemic opioids is minimized, and regional anesthesia involving continuous infusion of local anesthetic is usually avoided as these techniques may hamper the patient's ability to ambulate. A technique using continuous postoperative catheter-infused local anesthetic into the operative limb wound has been used in some centers to reduce requirements for systemic pain medication after infrainguinal revascularization procedures [46]. (See "Lower extremity nerve blocks: Techniques".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Aortic and other peripheral aneurysms" and "Society guideline links: Occlusive carotid, aortic, renal, mesenteric, and peripheral atherosclerotic disease".)

SUMMARY AND RECOMMENDATIONS

●General considerations – Surgical options for revascularization below the level of the groin (ie, infrainguinal) include endovascular (eg, angioplasty, stenting/stent-grafting) as well as open surgical (eg, bypass grafting, endarterectomy) procedures. (See 'General considerations' above.)

●Preanesthetic assessment – Goals of the preanesthetic consultation include ensuring optimal preoperative patient condition, with particular attention to management of cardiovascular risk and medical comorbidities such as chronic kidney disease, chronic obstructive pulmonary disease (COPD), and diabetes. (See 'Preanesthetic assessment' above.)

●Choice of anesthetic technique – Selection of anesthetic technique (eg, local or regional, neuraxial, or general anesthesia) depends on procedure-specific factors, particularly whether a percutaneous endovascular intervention or small incision or open surgical revascularization is planned, and the duration of the planned procedure. However, patient-specific factors are also considered (eg, recent administration of anticoagulant drugs, evidence of systemic infection, ability to cooperate, communicate, and tolerate supine positioning, as well as willingness to accept a technique with the possibility of awareness associated with conscious sedation rather than general anesthesia). (See 'Planned surgical technique' above and 'Choice of anesthetic technique' above.)

•Endovascular revascularization – For most patients undergoing an endovascular intervention, we suggest local anesthesia with monitored anesthesia care (MAC) (Grade 2C). Other anesthesia techniques are reasonable alternatives (eg, peripheral nerve block, general anesthesia). (See 'Endovascular revascularization' above.)

•Open revascularization – For patients undergoing open lower extremity infrainguinal revascularization, we suggest a neuraxial technique (spinal, epidural) provided there are no contraindications (Grade 2C). Examples of open procedures that may be appropriate for a neuraxial technique include femoral endarterectomy or other local procedures, femoral-to-popliteal or more distal bypass, and hybrid revascularization. However, general anesthesia is often selected due to the extent of the procedure or anticipated long duration, anticoagulation, infection, or patient or surgeon preference. (See 'Open surgical revascularization' above.)

●Intraoperative anesthetic management

•Intraoperative monitoring – In the absence of severe cardiac comorbidity, standard American Society of Anesthesiologists monitors are typically sufficient for elective endovascular and open infrainguinal revascularization procedures. Insertion of an intra-arterial catheter is reasonable for patients with significant cardiac dysfunction or those undergoing complex open procedures that may be of prolonged duration. (See 'Intravascular access and invasive monitoring' above.)

•Anticoagulation administration and monitoring – Unfractionated heparin is administered during open or endovascular surgical revascularization before occlusion of the peripheral artery to prevent arterial thrombosis. Although institutional practices vary, a target ACT value of 180 to 240 seconds (or a target twice the patient's baseline value) is often used. Heparin anticoagulation may or may not be reversed with protamine sulfate after open revascularization procedures (eg, 1 mg protamine per 100 units of heparin estimated to remain in the plasma); anticoagulation is typically not reversed after endovascular revascularization. (See 'Anticoagulation administration and monitoring' above.)

•Hemodynamic management – Generally, we attempt to maintain blood pressure within 20 percent of the patient's baseline and keep mean arterial pressure >65 mmHg. Similar to anesthetic management of patients undergoing endovascular or open aortic surgery, vasoactive drugs should be readily available to rapidly treat hypotension, hypertension, tachycardia, bradycardia, or arrhythmias (table 1 and table 2). (See 'Hemodynamic management' above.)

●Early postoperative and pain management – Care in the post-anesthesia care unit is typically adequate, although admission to an intensive care unit may be necessary for hemodynamically unstable patients or after complex infrainguinal revascularization procedures with significant blood loss. Pain management techniques are tailored to the extent of the procedure; most patients experience only mild-to-moderate pain, and are able to ambulate as soon as the first postoperative day. (See 'Postoperative anesthetic and pain management' above.)