Venous thromboembolism (VTE) consists of deep vein thrombosis (DVT) and pulmonary embolism (PE). While only 25% of patients with DVT have clinical evidence of PE, up to 80% can have clinically silent embolization to the lungs.136 Patients with DVT typically present with acute onset of lower extremity pain, swelling, and erythema. Chest pain, dyspnea, and sometimes hemoptysis are symptoms of PE.
Occasionally, patients can present with paradoxical arterial embolization (stroke, limb ischemia) in the setting of a patent foramen ovale.
Patients should be assessed for provoking factors such as recent surgery, hospitalization, immobilization, and long travel. Patients with active cancer, hypercoagulable disorders, and personal history of VTE are particularly at increased risk.
Physical exam of the lower extremities reveals edema, erythema, and calf or thigh pain upon palpation. Cyanosis and decreased pulses on exam especially if the limb is tense or exhibits neurological changes should raise concern for phlegmasia and constitutes a vascular emergency.
Patients with PE can present with tachycardia and low oxygenation on pulse oximetry. Distended neck veins and signs of right sided heart failure can be noted in intermediate risk PE. Patients with high-risk PE present with hypotension and can progress to hemodynamic collapse.
Duplex scanning of the lower extremities is the imaging modality of choice to diagnose acute DVT. The affected veins are non-compressible, dilated, and show no flow on doppler interrogation in the presence of occlusive thrombus.
Computed tomography angiography (CTA) provides fast and accurate imaging for the diagnosis of PE and the extent of embolization to the lungs, as well as the presence of right heart strain. Echocardiography is indicated for patients with submassive and massive PE to look for right heart strain (McConnell sign). Cross sectional imaging of the abdomen and pelvis with CTA or Magnetic Resonance Venography (MRV) is sometimes warranted to diagnose occult DVT and rule out extrinsic compression or to assess the proximal extent of the thrombus in patients with extensive iliofemoral DVT. Cross sectional imaging can also be used to assess thrombus burden in the IVC, the size of the IVC, and any associated anatomical abnormalities if IVC filter placement is considered.
Medical Management and Lifestyle Changes
Anticoagulation is the mainstay treatment for VTE.137 Patients can receive heparin drip in the inpatient setting as a bridge to oral therapy. Alternatively, direct oral anticoagulants (DOACs) can be used for outpatient therapy without hospitalization. Dabigatran, rivaroxaban, apixaban, and edoxaban (DOACs) are the anticoagulants of choice for outpatient VTE treatment over vitamin K antagonists, or LMWH.137
Patients with PE and hypotension (high-risk PE) should be evaluated by the PE response team (PERT) if available and treated with systemic thrombolytic therapy, suction thrombectomy or pulmonary embolectomy as indicated.138
A selective group of patients are considered at low risk of VTE recurrence or propagation and can be managed without anticoagulation. Patients with subsegmental PE and no proximal DVT can undergo clinical surveillance and patients with provoked isolated tibial vein DVT (unless symptomatic) can undergo serial ultrasounds to rule out proximal extension. Compression stockings should be offered to patients with DVT and significant swelling for symptomatic relief as needed. Leg elevation can also alleviate symptoms in patients with DVT.137
Risk Stratification for Surgery
Patients with iliofemoral DVT who have moderate-to-severe symptoms despite anticoagulation and compression therapy can be treated with catheter-directed thrombolysis or thrombectomy. Early thrombus removal can be offered to patients with acute iliofemoral DVT, who are at low risk of bleeding and are ambulatory with good functional capacity and an acceptable life expectancy.139
Patients with extensive DVT and limb threatening venous ischemia (phlegmasia) should be treated with emergent thrombus removal. Patients with PE and signs of right heart strain (intermediate and high-risk PE) could be treated with catheter-directed thrombolysis, suction thrombectomy or surgical thrombectomy in consultation with the PERT.
Patients with contraindication to anticoagulation and documented VTE should be considered for IVC filter placement in the setting of ongoing significant clinical risk for PE. IVC filter placement can be selectively placed in patients undergoing catheter directed interventions for DVT or PE with a defined plan for filter retrieval.140
A multidisciplinary approach to care can optimize outcomes. Medical specialists and team members 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 also be considered at time of surgical planning.7
Standard CBC, chemistry profile and coagulation profile are recommended before all interventions. D-dimer levels can help in diagnosing VTE. Patients with PE should have biomarker levels of troponin and Brain Natriuretic Peptide (BNP) checked as markers of myocardial injury. Baseline fibrinogen levels can be considered for patients undergoing thrombolytic therapy.
Preoperative Medication Adjustment
Patients who plan to undergo catheter directed intervention are typically hospitalized and should be stable on anticoagulation without evidence of bleeding. Hydration with normal saline or 5% dextrose/sodium bicarbonate before and after the procedure should be considered in patients at risk of postcontrast acute kidney injury, and if pharmacomechanical intervention with the is considered given the risk of hemolysis and renal insult (specifically with the Angiojet device (Boston Scientific)).141
Preoperative anticoagulation with heparin infusion can be usually continued but should be held prior to procedure if the perceived risk of bleeding is high..
- Perioperative antibiotics: Prophylactic antibiotics for open procedures should be considered perioperatively as for any other surgery, and for endovascular interventions on a case-by-case basis.
- Anticoagulation and its reversal: If patient is on oral anticoagulation preoperatively, then discontinue them as needed before the procedure to minimize bleeding complication. DOAC should be held for 48-72 hours before procedure. Warfarin should be discontinued 3-5 days in advance. Bridging with parenteral anticoagulation (UFH or LMWH) in appropriate patients with high thrombosis risk should be considered.
- Nephropathy: Techniques to minimize contrast nephropathy for endovascular procedures in patients with CKD should be utilized. While many different agents have been studied with varying success, only fluid loading has been consistently reported to be associated with better renal outcomes. If there is no contraindication fluid administration pre, intra and postoperatively is recommended. The issue to hold ACEs and ARBs is still not resolved and more research is needed.
- Allergy: Patients with allergy to intravenous iodinated contrast and scheduled for angiography should get premedication with prednisone 50 mg in 3 oral doses at 13 hours, 7 hours, and one hour prior to procedure, and Diphenhydramine 50mg one hour prior to procedure. Rescue dosing with IV solumedrol or Decadron can be used as needed. CO2 venography can also be considered as indicated.
- 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
Recommended Perioperative Consultations
Patients with family history of VTE or recurrent episodes of VTE should get a vascular medicine or hematology evaluation to identify hypercoagulable conditions and help to define a long-term anticoagulation plan.
The decision to intervene on PE is preferably made by a pulmonary embolism response team (PERT) which can include vascular surgery, vascular medicine, cardiology, pulmonology, interventional radiology, cardiac surgery, or other specialists depending on the local expertise.
General: Some procedures for venous thromboembolic disease, such as IVC filter placement, can be safely performed without anesthesia involvement.
Patients who may benefit from anesthesia care team involvement, include patients: • With high ASA classification.
• At-risk for respiratory or hemodynamic decompensation.
• Who are unable to tolerate awake procedure or supine position for a prolonged period of time.
• With procedures that are anticipated to be technically complex.
Postoperative pain for venous thromboembolic disease is commonly well-controlled with the intraoperatively administered local anesthetic and over-the-counter non-opioid analgesics, such as Acetaminophen.
a. Optimization and Risk Assessment
The acuity with which a venous thromboembolic disease presents can range from a stable patient awaiting a “semi-elective” procedure to a highly unstable patient requiring hemodynamic support and mechanical ventilation.
Consequently, the perioperative anesthesia process should be meticulous and include identifying potential risk factors, with particular attention paid to h/o hypercoagulable state, including h/o DVT, PE, pulmonary HTN due to potential chronic embolic burden (RV function), and anticoagulation.
b. Anesthesia Management
i) Anesthesia Techniques
MAC is preferred.
LA +/- sedation is the technique most commonly used for venous thromboembolic disease interventions.
Sedation is commonly provided with benzodiazepine, propofol, and/or dexmedetomidine infusion. Notably, avoidance of perioperative benzodiazepines has been recommended to reduce the risk of postoperative delirium.110 Dexmedetomidine, with its lack of respiratory depression, may be an attractive alternative. When used in high doses, however, hypotension and/or bradycardia resulting from Dexmedetomidine may outlast its sedative effects leading to prolonged stay in the PACU.
Opioids may be added for analgesia/sedation as well.
General anesthesia may be required in select patients who are unable to tolerate sedation, be supine for prolonged period of time, or who require a complex surgical intervention. Patients with high acuity (e.g., hypoxia or hypercarbia) and/or co-morbid burden may need endotracheal tube placement for mechanical ventilation. However, general anesthesia (or even deep sedation with propofol) can lead to hemodynamic collapse in unstable patients with PE. Therefore, in unstable patients with PE general anesthesia induction should either be avoided or conducted with great caution, with ECMO stand-by, if available.
ii) Monitoring and Access
All patients require the standard mandated by the American Society of Anesthesiologists including oxygenation (peripheral O2S), ventilation (CO2 monitor), circulation (ECG and BP) and temperature monitoring.67
In addition, all patients need an adequate IV-access and continuous oxygen supply.
• Indwelling Arterial Catheter: May be considered in patient with cardiac, pulmonary, renal, or metabolic conditions requiring continuous hemodynamic monitoring and/or blood sampling.
• Depth of Anesthesia Monitor (EEG, or EEG-based device): May be considered in elderly patients at risk, as increased anesthesia depth has been linked with postoperative cognitive decline and delirium.127, 128
• Brain Oxygenation: Monitoring using cerebral oximetry (similar principle as peripheral pulse oximetry) may be considered in patients with history of or at risk for stroke.129
• Cardiac Output Monitor: May be considered in those with tenuous cardio-pulmonary status or at risk of hemodynamic decompensation.
iii) Intraoperative Concerns
In most patients the intraoperative course is uneventful. However, hypotension, kidney injury, and/or hypothermia may ensue.
• Patients with Pulmonary Hypertension: For example, due to thromboembolic burden, should be identified in effort to prevent acute intraoperative right heart failure/ischemia (e.g., due to acute embolus or intraoperative hypercarbia leading to increase in right heart pressures). The differential diagnosis of an intraoperative hemodynamic collapse (code blue) should include acute RV ischemia/failure. Notably, the reverse Trendelenburg and not the Trendelenburg position may help unload right heart chamber. In patients with pronounced hypotension refractory to other therapies, emergent use of VA-ECMO should be considered.142 Bradycardia can also occur with rheolytic thrombectomy using the Angiojet device. Although often asymptomatic and self-resolving, it can lead to cardiac compromise in elderly patients with existing coronary disease and should be treated accordingly.
• Kidney Injury: While many different agents have been studied with varying success, only fluid loading (while avoiding overt volume overload) has been consistently reported to be associated with better renal outcomes. This is particularly important when rheolytic thrombectomy with the Angiojet device is performed, given the risk of heme pigment nephropathy from intravascular hemolysis.
• Hypothermia: In the elderly, hypothermia could be detrimental. Thermoregulation becomes impaired with aging.69, 70 Thus, proactive methods for temperature regulation should be aggressively utilized.7
c. 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, normothermia.
• Perioperative antibiotics are not routinely administered unless intravenous/intraarterial catheters are left in place for lytic infusion.
• Venous access should be performed under ultrasound guidance regardless of site (femoral, popliteal, jugular or other)
• Contrast volume should be minimized in patients with renal insufficiency by using dilute contrast or CO2 angiography to avoid Postcontrast acute kidney injury. Intravascular ultrasound can further decrease use of contrast and is the preferred modality for identifying venous outflow obstruction and sizing of venous stents.
• Full dose anticoagulation is administered prior to intervention (balloon angioplasty/stenting/mechanical thrombectomy) and ACT is maintained above 200s.
• For initiation/continuation of catheter-directed thrombolysis, the sheaths and catheters should be secured to the patient to prevent dislodgement during transportation.
• For initiation/continuation of catheter-directed thrombolysis, all the infusion lines should be clearly labeled with the respective medication for continuation of care.
• Patients Undergoing Catheter-directed Thrombolysis
- Administer low-dose heparin through the access sheaths and avoid full anticoagulation during the infusion of thrombolytic agent to minimize the risk of bleeding.
- Patients are on bed rest and should not ambulate.
- Patients can resume diet after the procedure but should be kept NPO subsequently for enough time in preparation for follow up procedure.
• Patient should be admitted to a monitored unit or intensive care unit per hospital protocol.
• Patients should be assessed at least every 2-3 hours for bleeding at the access site and remotely, extremity perfusion, and change in mental status.
• Patients should have labs (CBC, prothrombin time [PT], partial thromboplastin time [PTT], INR, and fibrinogen) checked periodically during the day per local protocol.
Steps Prior to Discharge
- Mobilization out of bed is initiated within 24 hours after termination of catheter-directed thrombolysis and removal of procedural sheath (s)
- Full anticoagulation should be resumed within 24 hours of termination of catheter directed thrombolysis and removal of procedural sheath (s) when deemed safe from a bleeding standpoint.
- IVC filter placement can be performed on an inpatient or outpatient basis and requires immobilization for 2-3 hours after procedure only.
- Perioperative antibiotics are discontinued in 24 hours.
- Pain medications can be administered orally or intravenously.
Steps After Discharge
- Patients with IVC filters should be periodically evaluated for retrieval within the recommended device instructions for use, when the risk of PE resolves or when they can resume anticoagulation.143
- The use of compression stockings is recommended for edema management.
- Follow up call within the first week after surgery.
Office / Telehealth Visit:
- Follow-up in a month after the procedure to assess clinical improvement and related imaging (venous duplex of the lower extremities for patients with DVT, Echo for patients with PE)
- Follow-up office visit with ultrasound after one year to assess clinical status, recurrence of VTE, and development of post-thrombotic syndrome or post thrombotic pulmonary hypertension.
- Proper follow-up with consulting services (such as hematology, nephrology, or the pulmonary hypertension clinic) should be established, as needed.
- Patients are typically kept on oral antithrombotic therapy
- Anticoagulation is recommended following deep venous intervention/stenting for chronic ilio-caval obstruction although the duration is still in evolution and is not well established and can vary from 4-6 weeks to a year based on local protocols and different clinical trial protocols.
- Patients can use Acetaminophen or NSAID over-the-counter pain medications, as needed.
- 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.