Orthopedic Disorders
Conditions
Keywords
opening injection pressure, femoral nerve block, fascia iliaca, ultrasound guided nerve block
Brief summary
Recent evidence suggests that injection pressure monitoring may be able to predict needle nerve contact in the brachial plexus nerve block model, but little is known about multifascicular nerves. The investigators hypothesize that injection pressure monitoring can reliably predict needle-nerve contact during femoral nerve block.
Detailed description
Single center, observational study. Patients scheduled for elective lower limb surgery with femoral nerve block will be recruited. Femoral nerve will be identified using a linear ultrasound transducer. A 22 GA 5 cm nerve block needle will be inserted with bevel downward and advanced to the following conditions: 1. Needle tip slightly indenting the fascia iliaca lateral to the femoral nerve 2. Needle tip advanced through fascia iliaca 3. Needle tip slightly indenting the anterior surface of the femoral nerve 4. Needle tip withdrawn 1 mm from nerve. At each of these conditions, 1 ml of dextrose solution will be injected via an automated pump at 10 ml/min and the spread of injectate observed sonographically. Simultaneously, a blinded observer will measure opening injection pressure using both an electronic and a mechanical transducer. If opening pressure reaches 15 psi, this investigator will halt the injection. In addition, minimum threshold current required to elicit a motor response will be recorded for conditions 3 and 4. Patients will be contacted at 7 days and asked about any adverse effects.
Interventions
PROCEDUREApposition of needle bevel against femoral nerve
Indentation of femoral nerve and fascia iliaca by block needle and measurement of opening injection pressure during the controlled injection of 1 ml of dextrose (D5W) solution
Sponsors
St. Luke's-Roosevelt Hospital Center
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Age 18-65 * ASA physical status I-III * scheduled for lower limb surgery where femoral block is part of intended analgesic plan
Exclusion criteria
* Contraindication to femoral nerve block (e.g. infection) * BMI \> 35 kg/m2 * inability to communicate postoperative symptoms * pre-existing neurologic deficits in the operative extremity * allergy to local anesthetics * history of opioid dependence
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Incidence of high opening injection pressure (15 psi or greater) when needle tip in contact with nerve | 1 minute |
Secondary
| Measure | Time frame |
|---|---|
| Incidence of high opening injection pressure (15 psi or greater) at other needle locations | 1 minute |
| Minimum threshold current to elicit a motor response with needle-nerve contact and needle disengagement | 1 minute |
| Incidence of paresthesias | 1 week |
Countries
United States
Outcome results
None listed