Ultrasound guidance improves the success rate of axillary plexus block: a meta-analysisABSTRACT
OBJECTIVE: To evaluate the value of real-time ultrasound (US) guidance for axillary brachial plexus block (AXB) through the success rate and the onset time.
METHODS: The meta-analysis was carried out in the Anesthesiology Department of the Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China. A literature search of Medline, EMBASE, Cochrane database from the years 2004 to 2014 was performed. The literature searches were carried out using medical subject headings and free-text word: "axilla", "axillary", "brachial plexus", "ultrasonography", "ultrasound", "ultrasonics". Two different reviewers carried out the search and evaluated studies independently.
RESULTS: Seven randomized controlled trials, one cohort study and three retrospective studies were included. A total of 2042 patients were identified. 1157 patients underwent AXB using US guidance (US group) and the controlled group included 885 patients (246 patients using traditional approach (TRAD) and 639 patients using nerve stimulation (NS)). Our analysis showed that the success rate was higher in the US group compared to the controlled group (90.64% vs. 82.21%, p < 0.00001). The average time to perform the block and the onset of sensory time were shorter in the US group than the controlled group.
CONCLUSION: The present study demonstrated that the real-time ultrasound guidance for axillary brachial plexus block improves the success rate and reduce the mean time to onset of anesthesia and the time of block performance.
Keywords:
Meta-analysis; Brachial plexus block; Ultrasonography
RESUMO
OBJETIVO: Avaliar o valor da orientação por ultrassonografia (US) em tempo real para bloqueio do plexo braquial por via axilar (BPBA) pela taxa de sucesso e tempo de latência.
MÉTODOS: Uma metanálise foi feita no Departamento de Anestesiologia do Segundo Hospital Afiliado da Universidade de Soochow, Suzhou, província de Jiangsu, China. Fizemos uma pesquisa bibliográfica nas bases de dados Medline, Embasa e Cochrane de 2004 a 2014. A pesquisa foi feita com títulos de assuntos médicos e palavras de texto livre: axilla, axillary, brachial plexus, ultrasonography, ultrasound, ultrasonics. Dois revisores fizeram a pesquisa e avaliaram os estudos de forma independente.
RESULTADOS: Sete estudos clínicos randômicos, um estudo de coorte e três estudos retrospectivos foram incluídos. Foram identificados 2.042 pacientes, dos quais 1.157 foram submetidos ao BPBA guiado por ultrassom (grupo US); o grupo controle incluiu 885 pacientes, dos quais 246 foram submetidos à abordagem tradicional (TRAD) e 639 à estimulação do nervo (EN). Nossa análise mostrou que a taxa de sucesso foi maior no grupo US em comparação com o grupo controle (90,64% vs. 82,21%, p< 0,00001). As médias do tempo necessário para fazer o bloqueio e do tempo de latência foram mais curtas no grupo US do que no grupo controle.
CONCLUSÃO: O presente estudo demonstrou que a orientação por ultrassom em tempo real para o bloqueio do plexo braquial por via axilar melhora a taxa de sucesso e reduz a média do tempo de início da anestesia e do tempo de execução do bloqueio.
Palavras-chave:
Metanálise; Bloqueio do plexo braquial; Ultrassonografia
Introduction
In recent years, the people paid more and more attentions on the local anesthesia, especially on peripheral nerve block technique.1and2 The traditional nerve block needs the help of anatomical landmarks, the arterial pulse, needling of abnormal sensation or nerve stimulator, but, with the rapid development of technology of ultrasound device, under the guidance of ultrasound nerve block anesthesia as a new field of an ultrasonic applications are gradually being retired by the attention, ultrasonic technology is a fundamental change in the way nerve block. Brachial plexus block are the most common methods used in peripheral nerve block. Peripheral nerve stimulation may have a high degree of accuracy and reliability for the axillary nerve block, but sometimes cause failure or incomplete block, even when took multiple stimulation and injection.3and4
Anesthesiologists have been able to observe the brachial plexus and the surrounding structures through the ultrasound guided puncture.5 So anesthesiologists can puncture into the target peripheral nerve accurately with real-time ultrasound. The injection process and the diffusion range of local anesthetics can also be observed by ultrasonography. The technology ensured the local anesthetic evenly spread to peripheral nerve, make local anesthetics fully infiltrate the nerve, significantly improve the success rate and reduce the complications.
Methods
Search strategy
The meta-analysis was carried out in the Anesthesiology Department of the Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China. A literature search of Medline, EMBASE, Cochrane database from the years 2004 to 2014 was performed. The literature searches were carried out using medical subject headings and free-text word: "axilla", "axillary", "brachial plexus", "ultrasonography", "ultrasound", "ultrasonics". Two different reviewers carried out the search and evaluated studies independently.
Inclusion criterion
All randomized, non-randomized controlled clinical trials, which compared ultrasound-guided AXB with traditional approach or peripheral nerve stimulation included.
Exclusion criterion
Abstracts, letters, case reports, comments, and conference proceedings were not included in the review. We exclude studies with small-sized group (<40 patients).
Date collection
Two reviewers independently extracted the following from each study: first author, publication data, study design, inclusion criteria and exclusion criteria. All disagreements were resolved through discussion. Non-comparative studies, cases series, and case report were not included.
Statistical analysis
We used Review Manager 5.2 to conduct the review. The Mantel-Haenszel method was used for the statistical analysis of the success rate, the mean time to onset of anesthesia and the time of block performance. Dichotomous data were analyzed for odds ratio (OR) and 95% effectiveness confidence interval. p ≤ 0.05 was considered statistically significant.
Results
Seven randomized controlled trials, one cohort study and three retrospective studies were included (Table 1).4,6,7,8,9,10,11,12,13,14and15 Our analysis showed that the success rate was higher in the US group compared to the controlled group (90.64% vs. 82.21%, total 1992 patients; Heterogeneity: Chi2 = 15.17; p < 0.00001;I2 = 47%; OR: 0.50; 95% CI [0.38, 0.65]) (Fig. 1). The average time to perform the block is shorter in the US group than the controlled group (total 1706 patients; Heterogeneity: Chi2 = 167.57, p < 0.00001;I2 = 96%; OR: 3.88; 95% CI [3.11, 4.65]) (Fig. 2). The onset of sensory time is also shorter in the US group than the controlled group (total 109 patients; Heterogeneity: Chi2 = 0.13, p = 0.004;I2 = 0%; OR: 3.68; 95% CI [1.15, 6.21]) (Fig. 3). The data analysis of subgroup showed that the success rate was higher in the US group compared to the NS group (91.42% vs. 83.80%, total 1699 patients; Heterogeneity: Chi2 = 9.51,p < 0.0001; I2 = 47%; OR: 0.50; 95% CI [0.36, 0.69]) (Fig. 4).
Summary of published information from controlled studies. RCT, randomized controlled trials.
Analysis of controlled studies for success rate of AXB: without ultrasound guidance vs. ultrasound guidance in the patients with AXB. 95% CI, 95% confidence interval; M-H, Mantel-Haenszel; df, degrees of freedom; OR, odds ratio; US, ultrasound.
Analysis of controlled studies for performance time of AXB: without ultrasound guidance vs. ultrasound guidance in the patients with AXB. 95% CI, 95% confidence interval; M-H, Mantel-Haenszel; df, degrees of freedom; OR, odds ratio; US, ultrasound.
Analysis of controlled studies for onset time of AXB: without ultrasound guidance vs. ultrasound guidance in the patients with AXB. 95% CI, 95% confidence interval; M-H, Mantel-Haenszel; df, degrees of freedom; OR, odds ratio; US, ultrasound.
Analysis of controlled studies for performance time of AXB: nerve stimulate vs. ultrasound guidance in the patients with AXB. 95% CI, 95% confidence interval; M-H, Mantel-Haenszel; df, degrees of freedom; OR, odds ratio; US, ultrasound; NS, nerve stimulate.
Discussion
Axillary brachial plexus block is applicable to operation of elbow and on the lower part of elbow, can prevent the tourniquet pain, also can increase the blood flow of upper limb.16,17and18 Axillary brachial plexus can block including median nerve, ulnar nerve, musculocutaneous nerve, radial nerve and all terminal branch. Musculocutaneous nerve is usually issued from axillary Fasciculus lateralis, so the AXB is often incomplete. The nerve stimulator and ultrasound guided axillary brachial plexus block significantly improve the success rate.
Although the nerve stimulator could be able to locate the target nerve, but because the injection of local anesthetic nerve had no idea to guarantee encased completely, so the nerve stimulator block has 10-15% failure rate.19and20 Ultrasonic monitoring can ensure that after the injection of drug, the nerve bundle was surrounding and infiltrating, thereby improving the axillary brachial plexus block success rate. However, the different levels of anesthesia operator may not fully be able to distinguish each nerve in ultrasound images. Especially the radial nerve were difficult to locate, and is often confused with axillary artery of posterior wall.21
The depth of insertion of the needle and the duration of axillary block placemen may affect the pain intensity.4,13,22and23 Patients who get AXB with ultrasound (US) guidance were less painful and more comfortable than the patients get AXB with neurostimulation.24 It was suggested that ultrasound requested less number of needle passes than neurostimualtion.7
In conclusion, ultrasound guidance for axillary brachial plexus block improved the success rate and decreased the performance time and onset time. The visualization technology greatly reduced the possibility of occurrence of error, such as perforating vessels and local anesthetics poisoning and improved the safety. So it is the ideal option for upper limb operation.
Acknowledgements
This work is supported by Grant No. SZD0613 (to Dr. Wang) from the Technology Bureau of Suzhou, China. Dr. Wang also received support from the Revitalizing the Key Talent's Subsidy Project in Science and Education (Jiangsu Province, China).
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