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Pain is a feeling of physical or emotional discomfort that’s different for every person and can range from mild to severe. When assessing your patient’s pain, follow the steps of the Clinical Judgment Measurement Model or CJMM to make clinical decisions about patient care.

Now, to better assess and intervene for your patient’s pain, let’s review the physiology of pain. So, the pain process is called nociception which involves pain receptors, which are free nerve endings called nociceptors located throughout the body, that send pain signals to the central nervous system. There are four main processes involved in pain signaling: transduction, transmission, perception, and modulation.

First, transduction is when a painful stimulus is converted into an electrical signal. This stimulus can be mechanical, like pinching someone; chemical, like a strong acid causing damage to the skin; or thermal, like spilling hot coffee on your lap.

Next, the pain signal is transmitted from the site of injury by nerve fibers to the spinal cord. During this time, the body uses motor reflexes to protect itself by moving away from the stimuli that’s causing the pain; for example, pulling back from someone pinching you, or wiping the hot coffee off your leg.

Then, perception occurs when the pain signal reaches the cerebral cortex. This is where an individual consciously perceives pain and its characteristics like location, intensity, and what makes the pain better or worse.

And finally, modulation refers to how the brain regulates pain by sending inhibitory messages to the spinal cord to slow transmission of the pain signal and to release endogenous opioids, or the body’s natural pain killers. For example, if a runner sprains their ankle, they may not feel the pain fully until after the race due to the effects of endogenous opioids.

Now, pain can be classified as acute or chronic. First, acute pain has a sudden onset and can be caused by trauma like cutting your finger, or chest pain from a myocardial infarction. It typically resolves within three months, or whenever the underlying cause resolves.

In contrast, chronic pain is mainly caused by long-term disorders like endometriosis, rheumatoid arthritis, or Crohn disease. It has a gradual onset and lasts more than three to six months, which is past the normally expected healing time.


  1. "Fundamentals of Nursing" Elsevier (2020)
  2. "Fundamentals of Nursing" Elsevier (2022)

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