Acute pain (AP) is the normal and predicted biological response to a noxious chemical, thermal, or mechanical stimulus associated with surgery, procedures, trauma, or acute illness. ^,,, This physiologic response may indicate an awareness to stimuli signaling potential tissue damage, beginning with sensitization in the periphery and extending to the central nervous system. AP symptoms can vary in severity, duration, and frequency depending upon the type of tissue injured and the extent of the injury. The release of substances such as prostaglandins, antihistamines, substance P, and other endogenous mediators trigger nociceptor sensitization and produce primary hyperalgesia at the site of injury. This peripheral sensitization (ie, increased sensitivity to peripheral nociceptors, often mediated by an inflammatory process) may lead to central sensitization (ie, increased excitability of spinal cord neurons triggered by release if neurotransmitters). Over time, an individual’s pain response changes with the inflammatory process, tissue healing, and physical movement which can vary by genetics, gender, psychological, and social factors. ^, Timely AP management can shape its subsequent presentation and if left untreated, or inadequately managed, can develop into chronic pain.

In the United States, AP is highly prevalent in both inpatient and outpatient settings. Nearly 100 million surgeries are performed annually with more than 80% of these surgical patients reporting acute postoperative pain. Of these, 20% experience severe pain within the first 24 hours after surgery. AP is highly prevalent in the emergency department accounting for over 70% of visits related to pain (eg, acute headache, musculoskeletal, neuropathic, or visceral pain). Outpatient settings in primary care and other specialty clinics (ie, neurology, chiropractic, orthopedics, dental clinics, among others.) commonly also encounter patients with AP.

The financial burden of poorly managed AP can result in prolonged or extended hospitalization, increased cost from complications including delayed mobilization, slower recovery resulting in more days of lost work productivity, and unnecessary partial or total disability. ^, Inadequate pain management may also lead to hospital readmissions, poor clinical outcomes, and reduced patient satisfaction. ^,, The financial implications have been estimated to affect 100 million adults at a cost of $635 billion annually in treatment and lost productivity.

Despite substantial advances in pain research, inadequate AP management remains prevalent and continues to pose a significant challenge for many clinicians. ^, For acute pain, the primary focus of treatment is to identify and eliminate the underlying source of nociception, in contrast to chronic pain management, which emphasizes reducing pain perception and improving function. However, in complex or refractory cases of acute pain, a more comprehensive evaluation is often necessary; one that incorporates the Biopsychosocial (BPS) Model to account for the multiple factors that influence the AP experience. ^, In this article, adapting this theoretic framework may identify the biological, psychological, and social factors influencing AP and highlights the importance of multimodal pain care and an interdisciplinary team approach. An outline of specific treatments, interventions, and AP education supports the rationale for individualized care by targeting not just the physical source of pain but also addressing emotional well-being and social factors to optimize recovery.

The overall goal is to achieve patient-centered pain care; to help an individual manage their symptoms, improve function and quality of life, and facilitate recovery, while minimizing adverse effects including overprescribing of opioids. ^,,, Moreover, adequate AP management can decrease the likelihood of developing chronic pain, increase patient satisfaction, and reduce long-term care costs along with disability.

Based on Engel’s BPS model of health and illness and other researchers, and adapted by Gatchel and colleagues for chronic pain, the BPS model reconceptualizes the complex interactions among the biological, psychological, and social processes associated with AP. As illustrated in Fig. 1 , the BPS model describes these complex interactions between central (eg, biologic, cognitive, somatic, and affective inputs) and peripheral (ie, immune response to pain through changes in autonomic and endocrine systems) processes through efferent and afferent feedback. These interactions are further influenced by an individual’s genetic disposition. The BPS model of AP lists the most common biological (eg, acute nonsurgical pain and surgical pain), psychological (eg, fear, anxiety, stress, depression, coping mechanisms, catastrophizing, previous pain experience, and substance use/opioid use disorder), and social (eg, social support, work/school/family expectations, cultural/environmental norms, socioeconomic status, barriers to acute pain and interactions with health care professionals) factors that may affect this AP experience. As illustrated in Fig. 2 , treatments and interventions can be individualized to tailor each patient’s plan of AP care.

A conceptual model of the BPS model in acute pain.

( Adapted from Gatchel and colleague’s Biopsychosocial Model of Chronic Pain. )

Biopsychosocial model of acute pain.