Orthopedic Surgical Procedures, Postoperative Pain
Conditions
Keywords
Lower Extremity, Sciatic Nerve, Anesthesia, Regional, Anesthetics, Local, Mepivacaine, Ultrasonography
Brief summary
This study was designed to assess whether the injection of local anesthetic into the nerve (intraneural), as opposed to around it (perineural), leads to longer anesthesia and analgesia of the leg. Some reports of accidental intraneural injection mention an extremely long duration. When different drugs and doses were evaluated in a clinical trial of intraneural injection, a longer-than-expected duration was reported. The investigators will compare the two types of injection using the same drug, so as to determine if there is an actual difference in duration.
Detailed description
This randomized, controlled trial will investigate prospectively for differences in sensory and motor block duration after intra- or perineural injection of 1.5% (wt/vol) mepivacaine, a short-acting local anesthetic.
Interventions
The injection will start as the needle penetrates the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as intraneural if nerve cross section expansion and a reduction in echogenicity are observed. Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach.
The injection will start as the needle indents the outermost discernible layer of the nerve (epineurium) under ultrasound guidance. The injection will be adjudicated as intraneural if the drug infiltrates the space between the epimysium of the surrounding muscles and the outer epineurium of the sciatic nerve. Short-axis real-time ultrasound imaging will be used, with an in-plane needle approach.
PROCEDUREFemoral Nerve Block
Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated.
Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication.
DRUGMepivacaine
Thirty milliliters of 1.5% (wt/vol) mepivacaine will be used for the sciatic nerve block.
Sponsors
University of Parma
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Caregiver, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Undergoing non-emergent orthopedic procedure of knee, leg, foot with thigh tourniquet * ASA Physical Status Class I-III * Consenting to surgery under peripheral nerve block anesthesia (sciatic + femoral/saphenous block)
Exclusion criteria
* Unable to understand or communicate for the purpose of the study * Exhibiting signs of neuropathy in the ipsilateral extremity * Inability to satisfactorily image the sciatic nerve in the opinion of the attending anesthesiologist
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Differences in Time to Resolution of Sciatic Nerve Block | <12 h | The time at which sensory and motor function of the sciatic nerve have recovered at least to the following criteria: * Sensory: patients feel discomfort when pricked with a thin needle (25G) * Motor: patients may move both toes and ankle, albeit with reduced strength This outcome measure will be examined by an investigator every 30-60 min and reported by patients as time to return of sensation and movement. The investigator-reported value will be preferred if both are available. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Block Onset Time | ≤30 min | Time to onset of sciatic nerve anesthesia, defined as meeting at least the following criteria: * Sensory: does not feel pain or discomfort when pricked with a 25G needle. * Motor: able to slightly curl toes; unable to flex the ankle. |
| Success Rate of Anesthetic Nerve Blocks | ≤30 min | The percentage of patients who attain the criteria for block success within 30 minutes of the injeciton. Investigators will also report the percentage of patients who successfully complete surgery without significant additional analgesia (see below); this will be defined as clinical success rate. |
| Incidence and Prevalence of Neurologic Disturbances | 30 days | Patients will be interviewed at \ 4 h (block resolution visit), 7 days and (if necessary) at 30 days to assess for residual neurologic disturbances in the sciatic nerve territory. The incidence/prevalence of these phenomena will be noted. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Extra- vs. Intraneural Minimum Electrical Stimulation Thresholds | (during the procedure) | The minimum electrical nerve stimulation threshold will be recorded as a function of needle tip position. |
Countries
Italy
Outcome results
None listed