Efficacy of Ultrasound-Guided Local Anesthetic Injection Into or Around the Sciatic Nerve for Lower Limb Anesthesia

Intraneural Injection of Ropivacaine for Subgluteal Sciatic Nerve Block Leads to Faster Onset and Higher Success Rates: a Randomized, Controlled Trial

This study was designed to assess whether the injection of local anesthetic into the nerve (intraneural), as opposed to around it (perineural), requires a shorter time to develop surgical anesthesia of the lower leg.

The investigators will compare the two types of injection using the same drug, so as to determine if there is an actual difference onset time. They will also examine the overall success rate of either kind of sciatic nerve blocks as the sole anesthetic for non-emergent orthopedic surgery.

The safety of these procedures will be examined by in-hospital and phone-call follow-up contacts.

Study Overview

• Status: Completed
• Conditions: Foot Diseases; Injuries, Knee; Orthopedic Disorders; Injuries, Leg; Injuries, Foot
• Intervention / Treatment: Procedure: Perineural Injection for Subgluteal Sciatic Nerve Block; Procedure: Femoral Nerve Block; Procedure: Intraneural Injection for Subgluteal Sciatic Nerve Block; Procedure: Patient-Controlled Postoperative Analgesia; Drug: Ropivacaine

Detailed Description

This will be a randomized, controlled, patient- and observer-blinded trial assessing block characteristics after intra- or perineural injection of ropivacaine for subgluteal sciatic nerve blocks performed for elective surgery of the lower limb.

• Study Type: Interventional
• Enrollment (Actual): 64
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Italy
  • PR
    • Parma, PR, Italy, 43126
      • Anesthesia, Critical Care and Pain Medicine - University of Parma

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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 any neurological disturbance of the ipsilateral lower extremity
• Inability to satisfactorily image the sciatic nerve in the opinion of the attending anesthesiologist

Study Plan

How is the study designed?

Design Details

• Primary Purpose: TREATMENT
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: TRIPLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
ACTIVE_COMPARATOR: Perineural; Patients in this group will receive a perineural injection for subgluteal sciatic nerve block under real-time, short-axis, in-plane ultrasound guidance, in addition to a femoral nerve block and patient-controlled postoperative analgesia. Ropivacaine will be used for the sciatic nerve block, whereas the choice of agent for the femoral nerve block is left to the attending anesthesiologist.	Procedure: Perineural Injection for Subgluteal Sciatic Nerve Block; 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.; Other Names: Epineural injection; Extraneural injection; Injection outside the common investing extraneural layer; Injection outside the paraneurium; Procedure: Femoral Nerve Block; Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated.; Procedure: Patient-Controlled Postoperative Analgesia; Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication.; Other Names: PCA; PCIVA; PCCPNB; Patient-controlled continuous peripheral nerve block; Drug: Ropivacaine; Thirty milliliters of 0.75% (wt/vol) ropivacaine will be used for the sciatic nerve block.; Other Names: Naropin; Naropine; Local Anesthetic
EXPERIMENTAL: Intraneural; Patients in this group will receive an intraneural injection for subgluteal sciatic nerve block under real-time, short-axis, in-plane ultrasound guidance, in addition to a femoral nerve block and patient-controlled postoperative analgesia. Ropivacaine will be used for the sciatic nerve block, whereas the choice of agent for the femoral nerve block is left to the attending anesthesiologist.	Procedure: Femoral Nerve Block; Patients will receive an ultrasound-guided femoral nerve block using a short- or long-acting local anesthetic, as deemed indicated.; Procedure: Intraneural Injection for Subgluteal Sciatic Nerve Block; 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.; Other Names: Subepineural Injection; Gluteal sciatic nerve block; Subparaneural injection; Injection beneath the common investing extraneural layer; Procedure: Patient-Controlled Postoperative Analgesia; Patients will receive a patient-controlled intravenous or perineural catheter-based analgesia, depending on their preference and the anesthesiologist's indication.; Other Names: PCA; PCIVA; PCCPNB; Patient-controlled continuous peripheral nerve block; Drug: Ropivacaine; Thirty milliliters of 0.75% (wt/vol) ropivacaine will be used for the sciatic nerve block.; Other Names: Naropin; Naropine; Local Anesthetic

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Onset Time of Sciatic Nerve Block	Time to onset of sciatic nerve anesthesia, defined as both 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.	≤30 minutes after block performance

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Differences in Time to Resolution of Sciatic Nerve Block	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.	<12 h
Success Rate of Sciatic Nerve Blocks	The percentage of patients who attain the criteria for block success within 30 minutes of the injection. 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."	≤30 min after block performance
Incidence and Prevalence of Neurologic Disturbances	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.	30 days after anesthesia performance

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Extra- vs. Intraneural Minimum Electrical Stimulation Thresholds	The minimum electrical nerve stimulation threshold will be recorded as a function of needle tip position.	During performance of nerve block (<30 min)

Collaborators and Investigators

• Sponsor: University of Parma

Publications and helpful links

General Publications

• Tran DQ, Dugani S, Pham K, Al-Shaafi A, Finlayson RJ. A randomized comparison between subepineural and conventional ultrasound-guided popliteal sciatic nerve block. Reg Anesth Pain Med. 2011 Nov-Dec;36(6):548-52. doi: 10.1097/AAP.0b013e318235f566.
• Andersen HL, Andersen SL, Tranum-Jensen J. Injection inside the paraneural sheath of the sciatic nerve: direct comparison among ultrasound imaging, macroscopic anatomy, and histologic analysis. Reg Anesth Pain Med. 2012 Jul-Aug;37(4):410-4. doi: 10.1097/AAP.0b013e31825145f3.
• Robards C, Hadzic A, Somasundaram L, Iwata T, Gadsden J, Xu D, Sala-Blanch X. Intraneural injection with low-current stimulation during popliteal sciatic nerve block. Anesth Analg. 2009 Aug;109(2):673-7. doi: 10.1213/ane.0b013e3181aa2d73.

Study record dates

Study Major Dates

• Study Start: December 1, 2011
• Primary Completion (ACTUAL): September 1, 2012
• Study Completion (ACTUAL): December 1, 2012

Study Registration Dates

• First Submitted: November 25, 2013
• First Submitted That Met QC Criteria: November 25, 2013
• First Posted (ESTIMATE): December 3, 2013

Study Record Updates

• Last Update Posted (ESTIMATE): December 4, 2013
• Last Update Submitted That Met QC Criteria: December 2, 2013
• Last Verified: December 1, 2013

More Information

Terms related to this study

• Keywords: Ultrasonography; Ropivacaine; Anesthetics, Local; Lower Extremity; Sciatic Nerve
• Additional Relevant MeSH Terms: Skin Diseases; Leg Injuries; Wounds and Injuries; Musculoskeletal Diseases; Knee Injuries; Foot Diseases; Foot Injuries; Physiological Effects of Drugs; Central Nervous System Depressants; Peripheral Nervous System Agents; Sensory System Agents; Anesthetics; Anesthetics, Local; Ropivacaine
• Other Study ID Numbers: ANEST-ORT-04