Ultrasound-guided Nerve Blocks for the Sciatic and Saphenous Nerves: Characteristics of the Single Penetration Dual Injection (SPEDI) Technique

Ultrasound-guided Nerve Blocks for the Sciatic and Saphenous Nerves: Characteristics of the Single Penetration Dual Injection (SPEDI) Technique

Ultrasound-guided Nerve Blocks for the Sciatic and Saphenous Nerves: Characteristics of the Single Penetration Dual Injection (SPEDI) Technique

Background and aims: Ultrasound-guided (USG) nerve blocks of the sciatic nerve (popliteal level = PL) and the saphenous nerve (mid-femoral level = MFL) provides analgesia following leg surgery. Traditionally two separate injections are performed. The aim was to describe a novel, faster USG block combination requiring only one skin penetration to block the sciatic and saphenous nerves; i.e. the SPEDI block = Single PEnetration Dual Injection. Methods: A randomized, controlled and double-blinded trial. Following ethics committee approval 60 patients will be randomized to the administration of an USG SPEDI block compared to two separate USG blocks of the saphenous (MFL) and sciatic (PL) nerves. Blocks will be performed after induction of general anaesthesia. Outcome measures will be performance time (primary outcome measure), Post-Anaesthesia Care Unit pain scores (VAS scores 0-10), block difficulty level (easy, middle, difficult), opioid consumption (in the PACU), serum-ropivacaine pharmacokinetics (blood sample 0-180 minutes). Both block combinations will be evaluated by MR imaging (MRI). Hypothesis: The USG SPEDI block combination is expected to be performed significantly faster without moving the leg, and achieve successful perioperative pain management. The SPEDI block may find important use in the emergency setting.

These are the patients that will be randomized to receive a SPEDI block of the sciatic and saphenous nerve with at single needle penetration of the skin

These are the patients that will be randomized to the administration of a popliteal sciatic nerve block combined with a mid-femoral saphenous nerve block with two separate injections

Single penetration dual injection (SPEDI) block technique to block the sciatic and the saphenous nerve with one needle penetration of the skin

Performance time (seconds and minutes). Time measurement from the time the ultrasound transducer is placed on the skin and until the needle is taken out of the body.

The measurement (seconds and minutes) will take place in the operating room. This will normally be within a time frame of 1 minute to 10 minutes.

When the patient are evaluated in the recovery unit upon arrival and when the patient is discharged from the recovery unit. This means from time 0 hours (arrival in the PACU) and normally until 2 hours after arrival in the PACU.

Sensory dermatome testing is done with cold ethanol on skin test. All dermatomes on the leg and foot are tested, and there is a comparison of the outcome between the operated leg and the not-operated leg.

Inclusion Criteria: lower leg surgery American Society of Anesthesiologist (ASA) score I-III Can cooperate in the study Speaks and understand the Danish language General anesthesia Exclusion Criteria: Intake of oral morphine above 40 mg per day Know allergy to ropivacaine Abuse of alcohol or other substance abuse Neuropathy Pregnant Nerve block contraindicated