Other Surgical Procedures
Conditions
Keywords
Sciatic Nerve, Ultrasound, Anesthesia, Regional, Orthopedic Surgery
Brief summary
For distal sciatic nerve block this prospective, randomised comparison with ultrasound guided distal subepineural block tested the hypothesis, that intraepineural injection of local anesthetic using nerve stimulation technique is common and associated with high success rate.
Detailed description
Classical methods for nerve localization (loss of resistance, cause of paresthesias, nerve stimulation technique)assumed that the target is a close approximation to the nerve, without epineural perforation. Intraneural injections were considered as evitable, with high risk for nerve damages. Ultrasound guidance provided for the first time a real-time visualization of the spread of local anesthetic. Some recent studies proved, that an intraneural injection using nerve stimulator technique is common and not necessarily accompanied with nerve damages. In the ultrasound group (group US) the investigators tested the hypothesis, that an intraneural injection of local anesthetic generate a high success rate and a short onset time without clinical apparent nerve damages. In the nerve-stimulation group (group NS) the investigators tested the hypothesis, that an intraneural injection of local anesthetic is common, and in case of intraneural injection accompanied likewise with high success rate and shorter onset time. For the sciatic division the investigators tested the hypothesis, that classical methods of nerve localization (nerve-stimulation technique, cause of paresthesias) are not able to avoid epineural perforation.
Interventions
DRUGmidazolam
Prior to performing the regional anesthesia the investigators administered midazolam as a premedication by mouth (3,75-7,5mg) or intravenously (2-3mg).
DRUGPrilocaine 1%
20ml Prilocaine 1% for distal sciatic nerve block (30ml Prilocaine 1% in outpatients)
10ml Ropivacaine 0.75% for distal sciatic nerve block (not in outpatients)
DEVICEultrasound guidance
In group US the sciatic nerve localization and needle guidance is realized using ultrasound.
DEVICEnerve stimulation technique
In the group NS sciatic nerve localization and needle guidance is realized using nerve stimulation technique. However, ultrasound is used observing (Observer) the procedure, but blinded for the physician (Anesthetist) performing the block.
Sponsors
Helios Research Center
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
* elective surgery on the foot or ankle * tourniquet distal of the knee * adult patients, 18-75 years old * ASA-risk-groups I-III (American Society of Anesthesiologists) * informed consent
Exclusion criteria
* severe coagulopathy * systemic inflammatory response * ASA-risk-groups \> III (American Society of Anesthesiologists) * drug allergy: local anesthetics * pregnancy, lactation period * participation in other studies * addiction to drugs or alcohol * non-cooperative patients
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Success Rate Without Supplementation | within 30-60 minutes after injection of the local anesthetic | After injection of local anesthetic a waiting period of 30-60 minutes was defined before completing a failed block. 1. success without supplementation = no additional analgetics or rescue blocks required (success rate without supplementation, outcome measure 1) 2. success with supplementation = analgetics or selective rescue blocks distal of the sciatic division required (success rate without supplementation and additionally all supplemented blocks, outcome measure 3) 3. failed block = change of anesthetic procedure (general, spinal) or rescue blocks proximal of the sciatic division |
| Time Until Readiness for Surgery (Minutes) | within 60 minutes after injection of the local anesthetic | — |
| Success Rate With Supplementation | later than 30-60 minutes after injection of the local anesthetic | After injection of local anesthetic a waiting period of 30-60 minutes was defined before completing a failed block. 1. success without supplementation = no additional analgetics or rescue blocks required (success rate without supplementation, outcome measure 1) 2. success with supplementation = analgetics or selective rescue blocks distal of the sciatic division required (success rate without supplementation and additionally all supplemented blocks, outcome measure 3) 3. failed block = change of anesthetic procedure (general, spinal) or rescue blocks proximal of the sciatic divisionSucces rate with supplementation |
Participant flow
Recruitment details
Adult patients were informed and included in the study in the anesthesiology outpatient clinic as part of normal pre-operative preparation. Using a computer-generated list of random numbers, patients were randomly allocated to either the nerve stimulation group (NS group, n=125) or the ultrasound group (US group, n=125).
Participants by arm
| Arm | Count |
|---|---|
| Group US Ultrasound guided block :
20ml Prilocaine 1% and 10ml Ropivacaine 0.75% (30ml Prilocaine 1% in outpatients) | 125 |
| Group NS Nerve stimulation technique:
20ml Prilocaine 1% and 10ml Ropivacaine 0.75% (30ml Prilocaine 1% in outpatients) | 125 |
| Total | 250 |
Baseline characteristics
| Characteristic | Group NS | Group US | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 30 Participants | 26 Participants | 56 Participants |
| Age, Categorical Between 18 and 65 years | 95 Participants | 99 Participants | 194 Participants |
| Age Continuous | 56.4 years STANDARD_DEVIATION 11.8 | 53.4 years STANDARD_DEVIATION 14.3 | 54.9 years STANDARD_DEVIATION 13.2 |
| Region of Enrollment Germany | 125 participants | 125 participants | 250 participants |
| Sex: Female, Male Female | 91 Participants | 107 Participants | 198 Participants |
| Sex: Female, Male Male | 34 Participants | 18 Participants | 52 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 66 / 125 | 24 / 125 |
| serious Total, serious adverse events | 0 / 125 | 1 / 125 |
Outcome results
Primary
Success Rate Without Supplementation
After injection of local anesthetic a waiting period of 30-60 minutes was defined before completing a failed block. 1. success without supplementation = no additional analgetics or rescue blocks required (success rate without supplementation, outcome measure 1) 2. success with supplementation = analgetics or selective rescue blocks distal of the sciatic division required (success rate without supplementation and additionally all supplemented blocks, outcome measure 3) 3. failed block = change of anesthetic procedure (general, spinal) or rescue blocks proximal of the sciatic division
Time frame: within 30-60 minutes after injection of the local anesthetic
Population: In the NS group two investigators were necessary in order to realize the blinded study protocol. For personnel reasons this was not possible in every case and led to deviations from the randomization protocol for seven patients in each group. These patients were excluded from the analysis.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Group US | Success Rate Without Supplementation | 112 participants |
| Group NS | Success Rate Without Supplementation | 73 participants |
Comparison: For sample size calculation we assumed a significance level of 0.05 and a success rate derived from clinical data of 75% in the nerve stimulation group and of 90% in the ultrasound group. With a group ratio of 1:1 and a power of 0.8, the required sample size was at least 226. For statistical analysis we used the exact Fisher test as a distribution-free, non-parametric test method.p-value: <0.05Fisher Exact
Primary
Success Rate With Supplementation
After injection of local anesthetic a waiting period of 30-60 minutes was defined before completing a failed block. 1. success without supplementation = no additional analgetics or rescue blocks required (success rate without supplementation, outcome measure 1) 2. success with supplementation = analgetics or selective rescue blocks distal of the sciatic division required (success rate without supplementation and additionally all supplemented blocks, outcome measure 3) 3. failed block = change of anesthetic procedure (general, spinal) or rescue blocks proximal of the sciatic divisionSucces rate with supplementation
Time frame: later than 30-60 minutes after injection of the local anesthetic
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Group US | Success Rate With Supplementation | 116 participants |
| Group NS | Success Rate With Supplementation | 85 participants |
Comparison: For sample size calculation we assumed a significance level of 0.05 and a success rate derived from clinical data of 75% in the nerve stimulation group and of 90% in the ultrasound group. With a group ratio of 1:1 and a power of 0.8, the required sample size was at least 226. For statistical analysis we used the exact Fisher test as a distribution-free, non-parametric test method.p-value: 0.05Fisher Exact
Primary
Time Until Readiness for Surgery (Minutes)
Time frame: within 60 minutes after injection of the local anesthetic
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Group US | Time Until Readiness for Surgery (Minutes) | 15.1 minutes |
| Group NS | Time Until Readiness for Surgery (Minutes) | 28 minutes |
Comparison: We used the log-rank test to compare the onset times. The significance level was defined with p\<0.05.p-value: <0.0595% CI: [13.6, 31.1]Log Rank