INTRODUCTION
A brachial block via the axillary approach is a common technique to provide anesthesia for upper extremity surgery. Peripheral nerve blocks offer numerous advantages, such as providing better postoperative pain scale scores, lower incidences of nausea and vomiting, shorter recovery time, early mobilization, decreased hospital stay, more stable hemodynamic results, and greater patient satisfaction. For the past decades, the nerve stimulator (NS) had been the gold standard for nerve localization in regional anesthesia. However, with recent developments in high-frequency imaging, using ultrasound (US) technology has significantly increased nerve localization.
A US-guided peripheral nerve block can be applied more successfully, easily, safely, and painlessly. This technique enables direct visualization of nerves and surrounding anatomy, continuous observation of the needle tip, and local anesthetics distribution. However, complications occur during the US alone. Therefore, using a combination of different techniques is recommended.
This study aims to compare peripheral nerve block guided with the NS with and without ultrasonography to investigate the time to perform the block, sensory and motor blocks onset time, pain related to the block procedure, and complications related to anesthesia.
METHODS
After obtaining Institutional Ethics Committee approval was received for this study from the Local Ethics Committee of İstanbul University, Medical Faculty of İstanbul (decision date: 12/04/2013, decision no: 412), a total of 60 patients undergoing elective upper extremity surgery between 18-70 ages and American Society of Anesthesiologists (ASA) I-IV status were enrolled in this prospective randomized study. Before conducting the study, all patients provided their informed consent. Then, they were randomly divided into two groups according to a randomization table: the NS-guided technique group and the NS with ultrasound (NU)-guided technique group. Patients with coagulation disorders, a history of allergy to local anesthetics, and neuromuscular and psychiatric diseases, a history of peripheral neuropathy, and patient refusal were the study’s exclusion criteria.
After arrival at the operating room, standard monitoring was used, including non-invasive arterial blood pressure, heart rate (HR), and pulse oximetry, and an intravenous catheter was placed to the forearm contralateral to the operating arm 30 min before the block, standard premedication was given intravenously (2 mg) to all the patients. Then, the patients were placed supine with the arm abducted 90 degrees.
The skin sterilization was made with chlorhexidine antiseptic solution.
In all patients, the block procedure was done by an experienced anesthesiologist applying the axillary approach technique.
Systolic arterial pressure, diastolic arterial pressure, mean arterial pressure, HR, and peripheral oxygen saturation (SPO2) was recorded in 0th, 5th, 10th, 15th, 30th, 45th, 60th, 120th, and 180th seconds.
In the NS group, after palpating the axillary artery’s pulse at the attachment of the major pectoral muscle, the nerve was localized using a 21 gauge, 100 mm needle connected to the negative lead of the NS (Stimuplex® HNS B/BRAUN). The NS was set at a pulse duration of 0.1 ms, a current intensity of 1.5 mA, and a frequency of 2 Hz. The stimulator flow was deducted after receiving the proper muscle contraction (wrist flexion for the nervus medianus, ulnar deviation for the nervus ulnaris, wrist extension for the radial nerve, and elbow flexion for the nervus musculocutaneous).
In cases of motor responses between 0.3-0.5 mA, after determining that there was no blood aspiration, an equal amount of a prepared solution containing a mixture of prilocaine 2% and lidocaine 2% was injected around each nerve by the axillary artery. This volume was one-quarter of the solution prepared earlier, with prilocaine 2% and lidocaine 2% using the height/5 formula.
In the NU group before the procedure, the US settings were set at depth: 3-5 cm, frequency: 8-14 Hz, and the stimulator parameter was set at 1.5 mA, 2 Hz, and 0.1 ms. The US probe was covered with a sterile sheath, coated with a sufficient amount of gel, and placed on the short axis of the humerus’ insertion point on the pectoralis major muscle.
After recognizing the pulsatile axillary artery by gentle suppression of the probe, a 100 mm 21 G needle was inserted into the skin at a 45° angle with the long axis approach.
When the needle was visible under the probe, it was directed to the target nerves. After obtaining the proper muscle contraction (wrist flexion for the nervus medianus, ulnar deviation for the nervus ulnaris, wrist extension for the nervus radialis, elbow flexion for the nervus musculocutaneous), the flow of the simulator was deducted. In cases of motor responses between 0.3-0.5 mA, after determining that there was no blood aspiration, an equal amount of a prepared solution containing a mixture of prilocaine 2% lidocaine 2% was injected around each nerve by the axillary. This volume was one-quarter of the solution prepared earlier, with prilocaine 2% and lidocaine 2% using the height/5 formula.
In all patients, the block procedure time, onset time of sensory and motor blocks, the number of skin punctures, procedure-related preoperative complications, procedure-related postoperative complications, visual analog scale (VAS) (0: No pain; 10: Worst imaginable) scores were recorded.
The block procedure time: Time from skin contact with either the US probe or the needle to the injection of the local anesthetic solution.
The onset time of the sensory and motor block: From the end of the injection of the local anesthetic solution, the onset time for the sensory block was evaluated with the pinprick test. For the motor block, the radial, ulnar, median, and musculocutaneous nerves were evaluated with the medical research council scale at 3, 5, 10, 15, 20, 25, 30, and 40 min, respectively.
Sensory Block
0: Normal sensation, 1: Decreased sensation (analgesia), 2: Complete sensory block (anesthesia).
Visual Analog Scale Score
When the sensory and motor blocks were completely performed, pain levels were assessed during the verbal pain scale.
0-2: No pain, 3-4: Mild pain, 5-6: Moderate pain, 7-8: Severe pain, 9-10: Excruciating pain.
Complications
Procedure-related preoperative complications: vascular puncture, hematoma, paresthesia, allergic reaction.
Procedure-related postoperative complications: After 24 hours, neurological complications, such as paresthesia and motor weakness, were evaluated.
Block Success was Evaluated as
Successful block: The operation was completed under block without any additional analgesia.
Partial block: The need for additional analgesia.
Failed block: General anesthesia was needed, or the procedure duration exceeded 20 min.
Insufficient block: In pain during the surgery, sedo-analgesia was administered with a bolus of 0.03 mg kg-1 midazolam IV and remifentanil infusion 0.05 mcg kg-1 h-1 under 3 L min-1 oxygen. If SPO2 <90% or apnea was longer than 20 sec-1 under sedo-analgesia, general anesthesia was administered.
Statistical Analysis
All data were evaluated with Statistical Package for Social Sciences for Windows v. 16.0 program. Data are given as mean ± standard deviation. Categorical data were compared with the chi-square test and continuous data with Fisher’s exact test. P values <0.05 were considered significant.
RESULTS
During the study, 70 patients were scheduled. Four patients refused to participate in the study, six patients did not meet the inclusion criteria, and 60 patients were enrolled in this investigation (Figure 1). Demographic data of the patients were not significantly different between the two groups (Table 1).
There were no significant differences in operation time and time to perform the block between the two groups (Table 2).
The number of skin punctures and VAS scores was significantly higher in the NS group than in the NU group (p=0.001, p<0.05) (Table 2).
There was not a statistically significant difference between the two groups in the usage of a total local anesthetic volume (p>0.05) (Table 2).
While there was no statistically significant difference in sensory and motor onset times of the ulnar nerve, the median nerve, and the radial nerve (p>0.05) in the NU group, there was a significant difference in the motor onset time of the musculocutaneous nerve in the NS group (p<0.05) (Figure 2).
There were no differences in the patients’ hemodynamic values between the two groups during the procedure (p>0.05).
Although the success rate was higher in the NU group, there was no statistically significant difference between groups (p>0.05) (Table 3).
While a total of 19 complications were seen in the NS group during the block procedure, four complications were observed in the NU group (p=0.0001) (Table 3); and complete recovery of sensory and motor function was observed in all studied patients.
DISCUSSION
In this study comparing the peripheral nerve block guided with the NS with and without ultrasonography, no significant difference was observed to perform the block between the two groups. While the two groups’ data consistently showed similar success rates, the complication rates and VAS scores were better in the US group.
In recent clinical studies, it was demonstrated that, in peripheral nerve blocks, the success rate was influenced by the local anesthetic solution type, concentration, and volume, and by patients’ demographic data (1-3). In our study, patients’ demographic data were similar, and we administered equal doses of the local anesthetic solution to each patient to provide the standardization between the groups.
Our study found no significant difference in the time to perform the block between the two groups. Cataldo et al. (4) showed that using the time was faster using the US popliteal block than with the NS. In Chan et al.’s (5) study, US was used with the NS to perform the block. They observed that an additional technique extended the time to perform the block.
The application time to perform the block varied with the different approaches used (6). Song et al. (7) demonstrated that performing the brachial block via the infraclavicular approach was faster than the axillary approach. This difference in the processing time was explained by fewer injection requirements in the infraclavicular approach. Imasogie et al. (8) performed the US-guided axillary approach brachial plexus block using four nerve injections in 10.9 min and with two nerve injections in 7.86 min.
Our study performed four nerve injections in 10.7 min in the NS group and 9 min in the NU group.
In our study, the number of skin punctures and VAS scores was significantly higher in the NS group than in the NU group. While VAS scores were not an objective criterion, the relationship between the skin punctures was demonstrated in different studies (9,10). On the other hand, Cataldo et al. (4) observed that while the number of skin punctures was higher in the US group, patient satisfaction was much better. This finding is likely because the time to perform the block was shorter when using the US.
Several trials demonstrated that the onset times of motor and sensory blocks were shortened by utilizing the US in peripheral nerve blocks (11,12). Our results showed that while the onset times of motor and sensory blocks were shorter in the US group, there was no significant difference except musculocutaneous nerve block. The smaller diameter of the musculocutaneous nerve than other nerves can make localization difficult with NS alone. It is possible to obtain a similar effect on onset times as in our study with US and NS technique in experienced hands (9).
The local anesthetic solution’s characteristics used, dose, and concentration affect the onset time of action. Casati et al. (9) using 20 mL ropivacaine 0.75%, the sensory and motor block action onset times were 18±6 and 25±8 min, respectively, while 14±6 and 24±8 min in the ultrasonography group. In our study, sensory and motor block action time was 12.8±5.5 and 17.3±5.4 min in the NS group, 12±4.3 and 15.2±5.2 min in the NU group. It was showed that sensory and motor block effect onset times are shorter in our study. This is due to the usage of a higher volume of lidocaine and 2% prilocaine in our study.
Training is essential for US techniques and takes longer than other techniques. Sandhu and Capan (13) stated that at least 20 procedures should be performed for successful block by ultrasonography. Therefore, all ultrasonographic blockage procedures were performed by an experienced anesthesiologist in our study.
Auroy et al. (14) stated that there is a possibility of developing systemic complications in the range of 0 to 25 at 10,000 according to the applied block type. In contrast, Zetlaoui et al. (15) reported developing generalized seizures in the axillary approach with brachial nerve block using ultrasonography. In this study, the short-term clinical picture after drug injection suggests that intravascular injection was performed.
Liu et al. (16) stated that they did not see systemic and local complications using ultrasonography. In our study, 26.6% of vascular pneumonectomy was performed in the NS group, and 25% of these patients had hematomas in their axillary region. In contrast, the vascular puncture was not performed in the NS group. Nevertheless, no systemic complications were encountered in any of our patients.
The frequency of nerve injury in the axillary approach to peripheral block ranges from 0.2% to 19% (17,18). In our study, paresthesia was observed in four patients (13.3%) in the NU group but nine patients (30%) in the NS group. Less skin fouling affects paresthesia frequency in the NU group. Nevertheless, none of the patients had neurological complications after the operation.
Study Limitations
The limitation of our study was that we did not perform a neurological follow-up for a long time after the operation.
CONCLUSION
In our study, while ultrasonography was associated with decreased pain and complications associated with the procedure, though not statistically significant, a higher success rate was obtained. Our study results support the routine use of ultrasonography with the NS.
Ethics
Ethics Committee Approval: Institutional Ethics Committee approval was received for this study from the Local Ethics Committee of İstanbul University, Medical Faculty of İstanbul (decision date: 12/04/2013, decision no: 412).
Informed Consent: Written informed consent was obtained from the patients who participated in this study.
Peer-review: Externally peer-reviewed.
Authorship Contributions
Concept: D.A., M.T., Design: D.A., Data collection or Processing: D.A., M.S.K., E.A.Ş., G.D., Analysis or Interpretation: D.A., M.T., Literature Search: D.A., M.S.K., E.A.Ş., Writing: D.A., G.D.
Conflict of Interest: No conflict of interest was declared by the authors.
Financial Disclosure: The authors declared that this study received no financial support.