The Physiological and Psychosocial Aspects of Acute and Chronic Pain
Acute pain is defined as a “sharp, stinging pain that is usually localized in an injured area of the body” (Straub, 2012, p. 419). This type of pain is normally associated with an injury or some type of surgery. According to Straub (2012), acute pain “can last from a few seconds to several months, it generally subsides as normal healing occurs,” but if left untreated can turn into chronic pain (Straub, 2012, p. 419). According to Australian and New Zealand College of Anesthetists (ANZCA) (n.d.), acute pain is “one of the activators of the complex neurohumoral and immune response to injury and both peripheral and central injury responses [has] a major influence on acute pain mechanisms” (p. 15). Some of the physiological aspects of acute pain can be “broadly classified as inflammation, hyperalgesia, hyperglycemia, protein catabolism, increased free fatty acid levels (lipolysis) and changes in water and electrolyte flux” and there are “cardiovascular effects of increased sympathetic activity and diverse effects on respiration, coagulation and immune function” (ANZCA, n.d., p. 16). When there is acute pain from an injury the body can “activate sympathetic efferent nerves and increase heart rate, inotrope, and blood pressure” as “sympathetic activation increases myocardial oxygen demand and reduces myocardial oxygen supply, the risk of cardiac ischemia, particularly in patients with pre-existing cardiac disease, is increased” (ANZCA, n.d., p. 19). According to ANZCA (n.d.), the “enhanced sympathetic activity can also reduce gastrointestinal (GI) motility and contribute to ileus” and if the acute pain is severe after certain types of surgeries it can contribute to “an inability to cough and a reduction in functional residual capacity, resulting in atelectasis and ventilation-perfusion abnormalities, hypoxemia and an increased incidence of pulmonary complications” as well as “suppression of cellular and humoral immune function and a hypercoagulable state following surgery, both of which can contribute to postoperative complications” (ANZCA, n.d., p. 19).
There are also psychological aspects of acute pain. According to ANZCA (n.d.), when the acute pain is not relieved it “may result in increasing anxiety, inability to sleep, demoralization, a feeling of helplessness, loss of control, inability to think and interact with others” and in the most extreme situations “where patients can no longer communicate, effectively they have lost their autonomy” (ANZCA, n.d., p. 21). It is also said that “in acute pain, attention has been focused on postoperative cognitive dysfunction (POCD)” and that “although the etiology of POCD is unknown, factors probably include dysregulation of cerebral neurotransmitters, patient factors (age, comorbidities, preoperative cognitive function and general health) surgical procedures (Coronary artery bypass) and perioperative drug therapy” (ANZCA, n.d., p. 21).
According to Straub (2012), chronic pain is defined as “pain that lasts 6 months or longer, long past the normal healing period, may be continuous or intermittent, moderate or severe in intensity, and felt in just about any of the body’s tissues” (p. 419). Chronic pain is said to lower an individual’s “overall quality of life and increases his or her vulnerability to infection and thus to a host of diseases” and takes “a devastating psychological toll, triggering lowered self-esteem, insomnia, anger, hopelessness, and many other signs of distress” upon the person (Straub, 2012, p. 419). According Straub (2012), chronic pain patients, “compared with acute pain patients, those with chronic lower back pain tend also to have higher rates of depression and personality disorders, and they are more likely to abuse alcohol and other drugs” and are more likely to “become even more sensitive to pain, [which is] a condition known as hyperalgesia” (p. 419). Straub (2012), also states that “both acute and chronic pain patients often show elevated scores on two [of] the Minnesota Multiphasic Personality Inventory scales: hysteria (the tendency to exaggerate symptoms and use emotional behavior to solve problems) and hypochondriasis (the tendency to be overly concerned about health and to over report body symptoms)” (Straub, 2012, p. 432).
Although some instances of “chronic pain might have originated with an initial trauma/injury or infection, or there might be an ongoing cause of pain…some people suffer chronic pain in the absence of any past injury or evidence of body damage” (The Cleveland Clinic Foundation, 1995-2014, What is chronic pain?, para. 2). The Cleveland Clinic Foundation (1995-2014), also reports that “there might be no known cure for the disease (such as arthritis or phantom pain) that is causing the chronic pain” or that “the cause of chronic pain might be unknown or poorly understood” (The Cleveland Clinic Foundation, 1995-2014, What is the difference between acute and chronic pain?, para. 1). It is for this reason that chronic pain is the most difficult to treat.
Australian and New Zealand College of Anesthetists. (n.d.). Acute pain management: Scientific evidence. Retrieved from http://www.anzca.edu.au/resources/college-publications/pdfs/Acute%20Pain%20Management/books-and-publications/1.%20Physiology%20and%20psychology%20of%20acute%20pain%20FINAL.pdf
Straub, R. O. (2012). Health psychology: A biopsychosocial approach (3rd ed.). New York, NY: Worth.
The Cleveland Clinic Foundation. (1995-2014). Acute vs. chronic pain. Retrieved from http://my.clevelandclinic.org/services/anesthesiology/pain-management/diseases-conditions/hic-acute-vs-chronic-pain
Image source for chronic pain cycle: Brain and Spine Institute of California. (n.d.). Understanding pain & pain scale. Retrieved from http://www.basicspine.com/pain-management/pain-scale-rating.html#axzz3kHD67gE6
Image source for crying lady: Damron Dr., A. (n.d.). Chronic pain. Retrieved from http://damronchiropractic.com/chronic-pain/
Image source for multiple injuries: Integrative Osteopathy. (2015). Acute pain. Retrieved from http://integrativeosteopathy.com.au/acute-pain/
Image source for neck pain: Lookfordiagnosis.com. (Last update: September 2014). Acute pain. Retrieved from http://lookfordiagnosis.com/mesh_info.php?term=acute+pain&lang=1