The ALOFT Pilot Trial

Background: Despite promising evidence suggesting benefit from neuraxial anesthesia for lower limb revascularization surgery, our data demonstrate that use of neuraxial anesthesia varies 6-fold between Canadian hospitals and is decreasing over time. Currently available evidence is largely observational. Only data from a multicenter, randomized trial of anesthesia type for lower limb revascularization surgery, powered for patient-reported outcomes and designed with patient and knowledge user partners, will provide the high-certainty evidence of the possible benefits of neuraxial anesthesia. Therefore, we are designing the Anesthesia for Lower limb revascularization to Optimize Functional ouTcomes (ALOFT) Trial to address this important question. Prior to conducting this full trial, the feasibility of the trial protocol must be demonstrated using a multicenter pilot design.

Overarching Aim: The ALOFT Pilot Trial will evaluate three pragmatic elements (recruitment, adherence, and follow-up) of neuraxial versus general anesthesia for lower limb revascularization surgery that are necessary to support a successful, large-scale evaluation.

Methods:

Design, setting and participants:

The ALOFT Pilot Trial is an assessor blinded, multicenter, individual patient, parallel-arm randomized controlled trial.

People => 18 years with a planned lower limb revascularization surgical procedure (on an elective or urgent basis): infrainguinal arterial bypass, femoral endarterectomy, patch angioplasty will be included.

Intervention: The intervention arm participants will be allocated to neuraxial anesthesia. The specific approach (spinal, epidural, or combined spinal and epidural) will be at the discretion of the treating anesthesiologist, as the underlying physiologic mechanisms and impacts are similar for both approaches.

Outcomes and sample size: Primary outcome is monthly recruitment. Secondary outcomes are intervention adherence, retention, and elicitation of patient, clinician and researcher-identified barriers. Our pilot trial sample size estimate is informed by a power calculation for the future full-scale trial. In the future trial, a sample of 778 (389/arm) will provide 90% power using ANCOVA to detect the 5% minimally important between group difference in the continuous WHODAS score assuming a common standard deviation of 20 and a correlation with baseline of 0.4 (as observed in our previous work4) as well as accounting for up to 10% attrition and up to 10% cross-over. For the pilot trial, a sample size of 90 directly links to our 3 feasibility outcomes.

Expertise: Our team features multidisciplinary clinical and methodological experts, nationally representative knowledge users and patient representatives.

Expected outcomes: Our objective is for results of the planned full trial to change practice in caring for lower limb revascularization surgery patients.

Inclusion criteria

• Age ≥18 years
• Planned lower limb revascularization surgical procedure (on an elective or urgent basis): infrainguinal arterial bypass, femoral endarterectomy, patch angioplasty
• Able to access a telephone for postoperative follow-up

Exclusion criteria

• Absolute contraindications to neuraxial anesthesia: impaired coagulation state (due to intrinsic, congenital or extrinsic (i.e., anticoagulant not held for guideline recommended period based on the American Society of Regional Anesthesia recommendations) factors), infection at the needle insertion point, increased intracranial pressure or intracranial mass, uncorrected hypovolemia or hypotension (systolic blood pressure <90 mmHg), severe uncorrected aortic stenosis)
• Traumatic arterial injuries as an indication for surgery
• Multiple sclerosis or demyelinating central nervous system conditions
• Known malignant hyperthermia or who require a malignant hyperthermia trigger-free anesthetic
• Pregnancy
• Prior enrollment in this study, or participating in another interventional trial that could interfere with interpretation of data for either study (may be acceptable if unrelated interventions/outcomes and study PIs mutually agree in writing to co-enrollment)
• Determination by the surgeon, anesthesiologist, or other clinician, that the patient would not be suitable for randomization