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A convenient alternative for monitoring opening pressure during multiple needle redirection

2014; Elsevier BV; Volume: 112; Issue: 4 Linguagem: Inglês

10.1093/bja/aeu083

1471-6771

Jui‐An Lin, H.-T. Lu,

Dental Anxiety and Anesthesia Techniques

Editor—Triple monitoring (ultrasound, nerve stimulator, and injection pressure) during nerve block has been proposed as the standard to minimize nerve injury.1Gadson J. Monitoring and documentation.in: Hadzic A Hadzic’s Peripheral Nerve Blocks and Anatomy for Ultrasound-Guided Regional Anesthesia. McGraw-Hill, New York2012: 71-79Google Scholar Ultrasound improves safety in nerve block, but it is relatively user-dependent and hard to differentiate between intra- or extra-fascicular injection by current resolution. Besides, the expert opinion did not reveal that high-definition ultrasound alone could be the answer for safe paraneural injection in popliteal sciatic nerve block in the future.2Abdallah FW Chan VW The paraneural compartment: a new destination?.Reg Anesth Pain Med. 2013; 38: 375-377Crossref PubMed Scopus (15) Google Scholar On the contrary, ultrasound guidance seems to encourage multiple injection and small readjustment of needle tip position has been suggested to ensure local anaesthetic spread to all trunks for supraclavicular block.3Perlas A Lobo G Lo N Brull R Chan VW Karkhanis R Ultrasound-guided supraclavicular block: outcome of 510 consecutive cases.Reg Anesth Pain Med. 2009; 34: 171-176Crossref PubMed Scopus (166) Google Scholar The effect of nerve stimulator might also be attenuated by previous local anaesthetic spread nearby. Therefore, once the needle has been redirected, monitoring ‘every’ opening pressure before local anaesthetic administration is the key to avoid intrafascicular injection, especially during performance of block within the nerve plexus or when the information about needle–nerve contact could not be confirmed. Half-the-air technique helps to keep injection pressure below 15 psi,4Tsui BC Li LX Pillay JJ Compressed air injection technique to standardize block injection pressures.Can J Anaesth. 2006; 53: 1098-1102Crossref PubMed Scopus (27) Google Scholar from which we provide an easy, convenient, and inexpensive setting to monitor opening pressure during multiple needle redirection. The extra-cost includes a three-way stopcock (B. Braun Discofix, Germany), a low-dead space (1.4 ml) extension tube (Innovative Extension Set ETC018, Taiwan), and a 20 ml syringe (BD Plastipak, Spain), which total £0.7 (€0.8/$1.1). The three-way stopcock has one male luer lock and two female luer connectors, one at the side and the other at the end. The extension tube connects the male luer lock to the patient. The test syringe is attached to the side female luer port and is ready to perform the pressure test when the three-way is turned on to the patient and the test syringe is held upright. Before local anaesthetic administration for a new needle tip location, opening pressure is tested simply by half-the-air at this setting (Fig. 1a). Local anaesthetic can then be injected into the space that has been tested (Fig. 1b). In addition to easy pressure monitoring, it also ensures that the total amount of local anaesthetic can be injected into the target site because the test syringe’s injectate consumed to hydrolocate the needle tip is the test volume (D5W or normal saline) instead of local anaesthetic. After injection of local anaesthetic, the volume of which retained in the dead space of the extension tube could be emptied by the volume in the test syringe. None declared.