From the Guidelines
The proper post-operative assessment for return of nerve function after a femoral nerve block and popliteal sciatic block involves evaluating the patient's ability to perform specific motor functions, such as straight-leg raising, at regular intervals, with the first assessment recommended at 4 hours from the time of the last local anesthetic dose. This approach is based on the guidelines for neurological monitoring associated with neuraxial block, which suggest that recovery of sensorimotor block can take several hours, typically 2-3 hours after intrathecal bupivacaine and 3-5 hours after epidural bupivacaine and/or lidocaine 1.
When assessing the return of nerve function, it is essential to evaluate both sensory and motor components. For a femoral nerve block, this includes testing sensation in the anterior thigh and medial leg, as well as evaluating motor function by asking the patient to extend the knee against resistance. For a popliteal sciatic block, assessment involves checking sensation in the lateral and posterior leg and entire foot, and testing motor function by having the patient plantarflex and dorsiflex the ankle and wiggle their toes.
Key points to consider in the assessment include:
- Evaluating the patient's ability to perform straight-leg raising at 4 hours from the time of the last local anesthetic dose
- Assessing sensory and motor function in the affected limb at regular intervals, initially hourly and then every 2-4 hours as recovery progresses
- Documenting findings using a standardized scale, such as the Bromage scale, to track the resolution or persistence of motor block 1
- Instructing patients not to bear weight on the affected limb until at least partial sensory and motor function returns to prevent falls and injury.
By following this systematic approach to assessing the return of nerve function after a femoral nerve block and popliteal sciatic block, healthcare providers can ensure timely identification of any potential complications and provide appropriate care to promote optimal recovery and minimize the risk of morbidity and mortality.
From the Research
Post-Operative Assessment of Nerve Function
The assessment of nerve function after a femoral nerve block and popliteal sciatic block is crucial for determining the return of nerve function. The following points highlight the key aspects of post-operative assessment:
- Motor Function Assessment: The assessment of motor function is essential for determining the return of nerve function 2. This can be done through various methods, including physical examinations and electrodiagnostic tests such as nerve conduction studies (NCS) and electromyography (EMG) 3.
- Sensory Function Assessment: The assessment of sensory function is also important for determining the return of nerve function. This can be done through methods such as the pinprick test 4.
- Timeline for Recovery: The timeline for recovery of nerve function can vary depending on the type and severity of the injury. In general, most severe nerve injuries are a combination of neurapraxia and variable degrees of axonotmesis, and complete recovery is expected after 3-12 months 3.
- Electrodiagnostic Prognostic Indicators: Electrodiagnostic tests such as NCS and EMG can provide prognostic information for recovery. For example, the observation of proximal to distal progression of small-amplitude, short-duration (SASD) motor unit potentials may be a significant prognostic indicator for recovery 3.
Key Considerations
The following points highlight key considerations for post-operative assessment of nerve function:
- Type of Nerve Block: The type of nerve block used can affect the assessment of nerve function. For example, a combined femoral and lateral femoral cutaneous nerve block with popliteal block can improve thigh tourniquet tolerance if supplemented with intravenous analgesics 4.
- Anesthetic Effect: The anesthetic effect of the nerve block can also affect the assessment of nerve function. For example, the duration of block performance and anesthetic effect can vary depending on the type of nerve block used 4.
- Patient Satisfaction: Patient satisfaction is an important consideration for post-operative assessment of nerve function. For example, patient satisfaction was similar in both the peripheral nerve block group and the spinal anesthesia group 4.