Therapeutic mechanisms of acupuncture therapy for acute pain in the emergency department

Acupuncture has been used for millennia to treat pain and in recent decades included as an evidence-based strategy for comprehensive pain care. More recently, acupuncture has also been used to treat acute peri‑operative pain and acute pain in the Emergency department (ED). While there are models of acupuncture's effect on chronic pain, the lack of application of those models for acute pain represents a gap in our scientific understanding. Acupuncture in the ED is a single-session dose intervention. In the context of clarifying significant details of an acupuncture intervention including needle insertion, needle perturbation (to obtain de qi), and needle retention, point specificity, adequate dose using local and distal acupoints, and functional MRI (fMRI) brain studies of acupuncture treatment for pain, a body and auricular model of acupuncture's specific effects in acute pain reduction is presented. The biomechanisms of body acupuncture are shown to be an interaction between local physiological responses at a needling site and peripheral and central analgesic responses. An auricular model conceptualizes how stimulation of the auricular branch of the vagus nerve also modulates autonomic and central nervous systems. Nonspecific effects of acupuncture are also discussed. The purpose of this review is to illustrate the biomechanisms of acupuncture for acute pain as a complex intervention that integrates patterns of change at physiological and molecular levels that can inform existing and future effectiveness research and facilitate assimilation of acupuncture in the ED.