Anesthesia Technique and Lower Limb Revascularization Patency

Study Overview
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Brief Summary
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The role of regional anesthesia in lower extremity revascularization procedures on reducing graft failure and need for reoperation remains unclear. In this study, we will analyze data from the multicenter National Surgical Quality Improvement Program (ACS NSQIP®) to assess the association between regional anesthesia (RA) and graft outcomes, as compared to general anesthesia (GA). Our primary objective is to determine for patients undergoing elective open lower limb revascularization, whether RA (spinal, epidural, and peripheral nerve block), compared to GA or general anesthesia with regional anesthesia (GA+RA), is associated with higher rates of patent graft within 30 days postoperatively (primary outcome).

Detailed Description
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Lower limb (infrainguinal) revascularization surgeries are performed for patients with blood flow occlusion, with the goals of improving pain and function. Graft patency is associated with higher quality of life scores. However, open lower limb revascularization is associated with a significant risk of graft failure. Multiple anesthesia options exist for elective open lower limb revascularization, including general and regional (spinal, epidural, peripheral nerve block). The literature has shown mixed results regarding the superiority of regional anesthesia over general anesthesia for morbidity and mortality. In this study, we will analyze data from the multicenter National Surgical Quality Improvement Program (ACS NSQIP®) to assess the association between regional anesthesia (RA) and graft outcomes, as compared to general anesthesia (GA).Our primary objective is to determine for patients undergoing elective open lower limb revascularization, whether RA (spinal, epidural, and peripheral nerve block), compared to GA or general anesthesia with regional anesthesia (GA+RA), is associated with higher rates of patent graft within 30 days postoperatively (primary outcome). Our secondary outcomes are major reintervention, amputation, bleeding requiring transfusion or secondary procedure, venous thromboembolism (VTE), myocardial infarction (MI) or stroke, pneumonia, discharge destination, postoperative length of stay, readmission rate, and death, all within 30 days postoperatively. There will be two composite outcomes: thromboembolism, and morbidity and mortality. We hypothesize that the use of RA is associated with increased graft patency after elective lower limb revascularization compared to GA. Compared to GA, RA is associated with decreased rates of major reintervention, amputation, death (30 days), bleeding requiring transfusion or secondary procedure, VTE, MI or stroke, pneumonia, mortality, composite thromboembolism, and composite morbidity and mortality.; Compared to GA, RA is associated with increased rates of discharge destination being home.

Official Title
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Association of Anesthesia Technique With Graft Patency Rates After Open Lower Limb Revascularization: a Retrospective Population Cohort Study

Conditions
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Regional Anesthesia, Vascular Grafting, Vascular Patency

Intervention / Treatment
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* Procedure: NSQIP Lower Extremity Open (LEO) procedure-targeted dataset (i.e. undergoing Lower extremity open revascularization) from 2014-2019


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All elective cases within the NSQIP Lower Extremity Open (LEO) procedure-targeted dataset (i.e. undergoing Lower extremity open revascularization) from 2014-2019 will be included. Hybrid procedures (where patients had both open and endovascular repair) are included, as long as there is an open component. Exclusion Criteria: Patients will be excluded if they underwent urgent or emergency surgery (identified using NSQIP variable EMERGNCY=1 OR ELECTSURG=0) local was the only anesthetic technique listed in principal and additional anesthesia technique. missing data on exposure, procedure name, or status of elective surgery. This includes having other or unknown for BOTH principal and additional anesthesia technique Patients with INR >= 1.5 on day of surgery

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 110 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Regional Anesthesia (RA)<br>RA Includes spinal, epidural, peripheral nerve block, excludes local infiltration (unlikely that any major open revascularization can be done under local) Defined as: NSQIP Principal (ANESTHES) or additional (ANESTHES_OTHER) anesthesia technique = regional, spinal, epidural, or MAC (in NSQIP RA/Spinal/Local + MAC are coded as MAC; while this includes local + MAC, it would be unlikely that local anesthesia would be sufficient for open revascularization) | Procedure: NSQIP Lower Extremity Open (LEO) procedure-targeted dataset (i.e. undergoing Lower extremity open revascularization) from 2014-2019<br>* Infrainguinal, open lower extremity revascularization procedures<br>|
| General Anesthesia (GA)<br>GA Defined as: NSQIP Principal or additional anesthesia technique = general Since GA is selected as the principal anesthetic technique by default when multiple techniques are present, GA + RA could potentially have been coded as GA if the optional variable of additional anesthesia technique is not filled in, leading to differential misclassification of patients with GA + RA (most likely epidural and peripheral nerve block) in the GA group. | Procedure: NSQIP Lower Extremity Open (LEO) procedure-targeted dataset (i.e. undergoing Lower extremity open revascularization) from 2014-2019<br>* Infrainguinal, open lower extremity revascularization procedures<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Graft Patency | Derived using NSQIP variables Most Severe Procedural Outcome LEO_MOSTSEVOUTCOME and Untreated Loss of Patency (i.e. not patent and no procedure done) LEO_ULP Yes if LEO_MOSTSEVOUTCOME is any of Clinically Patent Graft Patent graft, no stenosis Patent graft with stenosis No if LEO_MOSTSEVOUTCOME is any of Death Image-proven graft thrombosis or clinically evident thrombosis with no planned intervention Major Amputation New bypass in the treated arterial segment Not documented Other Revised graft with stenosis Revised graft, no current stenosis No if LEO_ULP = yes | 30 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Major reintervention | 1. Major reintervention, using NSQIP variable Major Reintervention on the Bypass defined as Yes if the patient underwent a subsequent procedure (new or revision lower extremity bypass operation, jump/interposition graft revision, bypass graft thrombectomy/thrombolysis) within 30 days of the original primary operation. | 30 days | 
| Amputation | 2. Amputation, using NSQIP variable Major Amputation (Transtibial or Proximal), defined as Yes if the patient underwent transtibial or more proximal amputation on the ipsilateral leg within 30 days of the original primary operation. | 30 days | 
| Bleeding requiring transfusion |  | 30 days | 
| Venous thromboembolism |  | 30 days | 
| MI or stroke |  | 30 days | 
| Pneumonia |  | 30 days | 
| length of postoperative hospital stay |  | 30 days | 
| Discharge destination | dichotomize as home vs. not home | 30 days | 
| Readmission rate |  | 30 days | 
| death |  | 30 days or in-hospital admission | 
| Composite thromboembolism | combination of venothromboembolism, MI, stroke | 30 days | 
| Composite Morbidity and Mortality | combination of bleeding requiring transfusion, venothromboembolism, MI, stroke, pneumonia, death | 30 days |