The Impact of a Preoperative Nerve Block in Foot and Ankle Surgery on the Consumption of Sevoflurane
Status:
Recruiting
Trial end date:
2021-08-01
Target enrollment:
Participant gender:
Summary
Reconstructive foot and ankle surgery is performed under general anesthesia. Included in this
spectrum of surgery are ankle arthroplasties, various fusions, corrective arthrodesis, and
more. Pain control for after the surgery can be achieved purely with intravenous and oral
pain medication or in combination with freezing of the nerves. Nerve freezing (nerve block)
placed before surgery has the potential to substantially reduce the amount of inhaled
anesthetic given to the patient during surgery. This can benefit the patient with being more
awake and crisp more quickly after surgery. It can also reduce cost to the system. A further
benefit which has received very little attention so far, is that reducing the amount of
inhaled anesthetic given also lowers the environmental footprint created by the anesthetic.
For the region of the foot and ankle to be fully frozen, both the sciatic nerve and the
saphenous nerve must be successfully blocked. Sciatic nerve blockade is most commonly
achieved by blocking the nerve in the popliteal fossa. This block is named popliteal nerve
block.
The investigators will examine and quantify the amount of inhaled anesthetic used for each
case and will compare how the consumption is affected by whether the nerve blocks are applied
before or after surgery. Patients will have two nerve block catheters (popliteal and
saphenous catheter) placed under ultrasound-guidance prior to the case by an experienced and
specifically trained anesthesiologist. The catheters will be loaded with a solution to which
the anesthesiologist is blinded. It will either be local anesthetic or 5% dextrose (sham).
The general anesthetic will be conducted according to a research protocol with anesthetic
depth being the targeted endpoint. Measurements of the required MAC-Value (minimum alveolar
concentration) of inhaled anesthetic will be recorded every five minutes by a study team
member. At the end of the case the anesthesiologist will be unblinded to the solution. Should
the patient have received sham initially, they will now receive the full dose of local
anesthetic prior to being woken up.