Stops Uncontrolled High-Pressure Injections in Peripheral Nerve Blocks

The risk of peripheral nerve injury remains a serious complication, with an incidence of postblock neuropathy reported up to 3 %. The causes include direct needle trauma, chemical injury from local anesthetics or adjuvants, as well as ischemia from vasoconstriction of nutrient vessels within the nerve.²

A central factor influencing the development of such nerve injuries is the injection technique – particularly the control of injection pressure. Studies have shown that an injection pressure of 15 to 20 psi is consistent with safe needle placement. Exceeding this threshold, especially during the initial injection (opening injection pressure, OIP), may indicate intraneural placement – with potentially serious consequences.²

Studies show that injection pressure currently represents the only objective criterion for detecting needle to nerve contact.³ The use of the subjective "hand-feel" technique to avoid high injection pressures is, unfortunately, not reliable as studies with experienced users have shown.¹

The NerveGuard is a disposable in-line manometer⁴ and works as a hard-stop limiter⁵/pressure-limiter⁴ rather than a monitor. In-line pressure measurement shows high sensitivity for detection of needle to nerve contact.⁶ Allowing identification of an inappropriate needle position, and reducing injections performed with excessive pressure.⁷

Studies:

¹ Choquet O., Capdevila X. Ultrasound-guided nerve blocks: the real position of the needle should be defi ned, Anaesth. Analg. 2012 May; 114(5): 929–930
² Neil J. M., Brull R., Horn J. L., Liu S. S., McCartney C. J., Perlas A., Salinas F. V., Tsui B. C. The Second American Society of Regional Anesthesia and Pain Medicine Evidence-Based Medicine Assessment of Ultrasound-Guided Regional Anesthe-sia, Reg. Anaesth. Pain Med. 2016 March–April; 41(2): 181–194
³ Robards C., Hadzic A., Somasundaram L., Iwata T., Gadsden J., Xu D., Sala-Blanch X. Intraneural injection with low-current stimulation during popliteal sciatic nerve block, Anesth. 2009 Aug; 109(2): 673– 677
⁴ Vassiliou T., Müller H. H., Limberg S., De Andres J., Steinfeldt T., Wiesmann T. Risk evaluation for needle-nerve contact related to electrical nerve stimulation in a porcine model, Acta Anaes-thesiol. Scand. 2016 Mar; 60(3): 400–406
⁶ Hadzic A., Dilberovic F., Shah S., Kulenovic A., Kapur E., Zaciragic A., Cosovic E., Vuckovic I., Divanovic K. A., Mornjakovic Z., Thys D. M., Santos A. C. Combination of intraneural injection and high injection pressure leads to fascicular injury and neurologic deficits in dogs, Reg. Anesth. Pain Med. 2004 September–October; 29(5): 417–423
⁸ Gadsden J., Choi J. J., Lin E., Robinson A. Opening injection prewssure consistently detects needle-nerve contact during ultrasound-guided interscalene brachial plexus block, Anesthesiology 2014 May; 120(5): 1246–1253
⁹ Gadsden J., Latmore M., Levine D. M., Robinson A. High Opening Injection Pressure is Associated With Needle-Nerve and Needle-Fascia Contact During Femoral Nerve Block, Reg. Anesth. Pain Med. 2016 Jan–Feb; 41(1): 50–55
¹⁰ Steinfeldt T., Graf J., Schneider J., Nimphius W., Weihe E., Borgeat A., Wulf H., Wiesmann T. Histological consequences of needle-nerve contact following nerve stimulation in a pig model, Anesth. Research and Practice 2011; Article ID 591851: 0–9
¹¹ Lundborg G., Myers R., Powell, H. Nerve compression injury and increased endoneurial fluid pressure: a „miniature compartment syndrome“, J. Neurol. Neurosurg. Psychiatry 1983 Dec; 46(12): 1119–1124