Pathophysiology of Acute Pain


Pathophysiology of Acute Pain

Acute pain, also called nociceptive pain, begins suddenly and is a normal response that the body produces for the purpose of “alerting the individual to a condition or experience that is immediately harmful to the body” and prompting them to take actions to address the problem (Huether & McCance, 2017, p. 339). Acute pain occurs when peripheral pain receptors are activated and the impulses transmitted by A delta and C fibers (Huether & McCance, 2017). Acute pain typically comes and goes, lasting anywhere from minutes to days up until 3 months, and can be classified as three different types: somatic, visceral, and referred (Huether & McCance, 2017). Somatic pain can be either sharp and well-localized, or dull, achy, and poorly localized, and it originates from the skin, muscles, and joints (Huether & McCance, 2017). Visceral pain can be aching, gnawing, throbbing, or cramping, and is felt in the organs or the lining of body cavities (Huether & McCance, 2017). Acute pain can result in physical symptoms such as anxiety, hypertension, elevated heart rate, and sweating (Huether & McCance, 2017).

Pathophysiology of Chronic Pain

Chronic, or persistent pain, is pain that lasts for over 3-6 months and can be continuous or intermittent (Huether & McCance, 2017). Unlike acute pain, chronic pain serves no purpose and is not well understood, but it is thought to originate when changes in the peripheral and central nervous systems leads to the disruption of nociception and pain modulating processes (Huether & McCance, 2017). Chronic pain is subjective and affects each person differently. It causes ongoing stress, both physically and mentally. Chronic pain may be associated with cognitive deficits and a lower tolerance for coping with that pain (Huether & McCance, 2017).

Pathophysiology of Referred Pain

Referred pain occurs when pain is felt in another area instead of the area that is the actual source of the problem. The referred pain area shares the same spinal segment as the actual pain source and the brain is unable to pinpoint the exact location of the pain (Huether & McCance, 2017). Referred pain occurs due to the activation of nociceptors within the viscera causing a perception of pain that is localized to a specific area.

Similarities and Differences

Acute, chronic, and referred pain are similar in that they each begin with a response to a stimulus and originate from visceral, cutaneous, or somatic sources in the body (Huether & McCance, 2017). When the nerve endings of C fibers and A delta fibers are stimulated, it creates the sensation of pain (Hammer & McPhee, 2014). The pain signals are transmitted to the brainstem, cerebral cortex, and spinal cord (Huether & McCance, 2017). Acute pain comes on suddenly and gets better with time and healing, while chronic pain is a state of recurrent and persistent pain over time with no relief (Huether & McCance, 2017). Acute pain is well understood physiologically, while chronic pain is not. Referred pain is different from both acute and chronic pain because the source of the pain may not be where the person actually feels the pain.

How Selected Factors Impact Pain

The perception of pain may vary based on factors such as gender, age, life circumstances, and behaviors. The pain perceptions and adaptive responses are sometimes different depending on age groups. For example, elderly people may have a lower pain threshold and more serious responses due to the decline in the body’s systems or the presence of chronic diseases that they have developed over time (Huether & McCance, 2017). Studies have shown that gender is a significant factor in pain tolerance, perception, and responses; as men and women feel pain in different ways and respond to treatments differently (Ackerman, 2011). Women also report more severe and longer lasting pain when compared to men (Ackerman, 2011). This is due in part to differences in each gender’s body pharmacodynamics and pharmacokinetics, as well as differences in metabolism (Ackerman, 2011). Women tend to have lower body weights than men, but have higher body fat percentages, which can affect how medications are distributed and metabolized in the body (Ackerman, 2011). Another reason pain perception differs between gender is related to the effects of female hormones estrogen and progesterone on the brain and spinal cord, and their influence on the regulation and transmission of impulses that transmit pain (Ackerman, 2011). Studies have also suggested that “female gender-specific diseases may be related to estrogen receptor abnormalities” (Ackerman, 2011). Additionally, estrogen affects the central nervous system levels of dopamine and serotonin, and its suggested that “women’s greater sensitivity to pain may be dependent on the fact t