What is pain?

Pain is defined by the IASP Council as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage.”

There are several different types of pain, and treatment may vary from one type to the next. The different types of pain are: 

  • Nociceptive pain – This is pain associated with damage to the body’s tissues and is often a result of injury such as surgery or a fall. It typically responds well to opioid and non-opioid medications. There are two types of nociceptive pain, which each travel through different pathways to reach the spinal cord: 
    • Somatic pain is pain felt in the bone, muscles, skin, and connective tissues. It is specific to the area that’s affected and is easy to pinpoint. Depending on the specific location and tissue, somatic pain may be described as throbbing, sharp, burning, or aching.
    • Visceral pain is pain associated with the internal organs and is more difficult to localize. Visceral pain is often described as aching or pressure, but can also be sharp, gnawing, colicky,  or cramping. Note that visceral pain can cause referred pain, which is pain felt elsewhere in the body.
  • Neuropathic pain – Neuropathic pain is associated with damaged or abnormal nerve tissue. Examples of neuropathic pain include trigeminal neuralgia, shingles, amputation (phantom limb pain), and diabetic neuropathy. It is often described as intense burning, “pins and needles,” shooting, or electric shocks. Additionally, the patient may describe sensitivity to touch or movement. Neuropathic pain is often treated with adjuvant medications including skeletal muscle relaxants and antidepressants. Unfortunately, those with neuropathic pain tend to have more severe pain and it can be difficult to manage.
  • Nociplastic pain – According to the IASP, nociplastic pain is pain that “arises from altered nociception despite no clear evidence of actual or threatened tissue damage.” This alteration in nociception causes the activation of peripheral nociceptors which leads to sensations of pain. This is thought to be the type of pain associated with fibromyalgia, tension headaches and some low back pain.

It’s also important to distinguish between acute and chronic pain. 

Acute pain lasts less than six months and is generally associated with a specific injury such as surgery or a broken bone. It is considered protective and resolves once the injury heals. Chronic pain, however, is pain that has lasted longer than six months and is felt most days. Chronic pain can be related to a variety of conditions such as fibromyalgia, cancer, back pain, headaches, and arthritis. Individuals with chronic pain are at high risk for anxiety and depression, both of which can exacerbate pain perception. Chronic pain has detrimental effects on both quality of life and work productivity.

The Body’s Response to Pain

Though pain is an unwelcome and unpleasant experience, it actually is highly beneficial to the body. When the body undergoes an injury, pain encourages us to behave in a way that promotes healing. For example, if you sprain your ankle, pain signals prevent you from continuing to walk on the injured ankle. The result is that you rest the injured body part, which helps it to heal. 

When the body is exposed to a painful stimulus, the stimulus is transformed into a nerve impulse which travels to the brain. The brain then perceives the pain, bringing it into conscious awareness. The body’s response to pain is widespread and affects every body system: 

  • Nervous system – Pain activates the SNS in the “fight or flight” response.
  • Respiratory system – Pain causes tachypnea and shallow breathing. With shallow breathing, the individual is at higher risk for pneumonia.
  • Cardiovascular system – Pain causes tachycardia and hypertension.
  • Gastrointestinal system – Pain can cause nausea and vomiting, delayed gastric emptying, reduced gastric motility, and constipation.
  • Endocrine system – Pain causes hyperglycemia and increases cortisol levels.
  • Neurological system – Pain causes depression, fear, anxiety, and difficulty concentrating. In addition, chronic pain has shown to cause the brain to shrink over time.
  • Musculoskeletal system – Pain leads to muscle tension, shaking and shivering.
  • Immune system – Pain increases the individual’s risk for infection. Researchers found that pain reduces the amount of available oxygen which makes the skin less effective at fighting off pathogens.

Pain Severity Assessment

Pain assessment is multifactorial, with a key component being the severity of pain. The most commonly used pain scale is the 0 to 10 scale, but there are actually multiple tools available. Which one is utilized depends on the patient’s age, cognitive abilities and level of consciousness. Some common pain scales used are: 

  • Numeric Rating Scale (NRS): With this scale, the patient self-reports their pain on a 0 to 10 scale. 0 indicates no pain and 10 indicates the worst pain imaginable. The numerical scale is ideal for patients with normal cognition who are able to self-report their pain. It is not suitable for those with dementia, reduced LOC or young children. 
  • Adult Non-Verbal Pain Scale (NVPS): This pain scale is utilized in individuals who are not able to self-report their pain. It looks at behavioral cues and vital signs to determine if the individual is feeling pain. The NVPS assigns points in five categories: facial expression, level of activity, presence of guarding, vital signs, and respiratory status. This pain scale is suitable for adults with dementia, individuals on palliative care and patients who are non-communicative such as those with global aphasia.
  • PAINAID: This is another behavioral pain scale utilized for patients who are unable to self-report pain, and is specific for individuals with advanced dementia. The PAINAID scale looks at breathing, vocalization, facial expression, body language, and consolability as indicators of pain. 
  • CPOT – The critical care pain observation tool is used in the ICU and looks at facial expression, body movement, compliance with the ventilator, and muscle tension.
  • FLACC – Pediatric: The FLACC scale was originally developed and is validated for use in children aged 2 months to 7 years as a way to assess postoperative pain, though you may see it also used during potentially painful procedures such as getting stitches. The FLACC scale looks at behavioral cues including facial expression, leg position and activity, level of activity, crying, and consolability.
  • Wong-Baker Faces Scale: This easy-to-use pain scale is utilized for those who are able to self-report pain. While it may be used in adults as an alternative to the NRS, it is especially appropriate for children over the age of three and adults who have difficulty communicating verbally or who have mild to moderate cognitive impairment. To use this scale, the individual is asked to select the picture that best describes their pain.
  • The Modified Pain Assessment Tool (mPAT): The mPAT scale is an observational tool utilized in neonates aged 24 weeks to 6 months. It looks at several factors including posture, sleep pattern, expression, cry, color, respirations, heart rate, oxygen saturation, blood pressure, and the nurse’s overall impression of the child.
  • Neonatal Pain Agitation and Sedation Scale (nPASS): This scale looks at both behavior and physiology to assess pain and sedation in neonates of all ages, including preterm infants in the NICU. This scale looks at crying and irritability, behavior, facial expression, extremity tone, and vital signs.  

Full Pain Assessment

When possible, pain assessment goes beyond determining the severity and looks to fully describe the pain. One commonly used mnemonic is OPQRST:

  • O (Onset): When did the pain start? Did it come on suddenly or gradually?
  • P (Provocation/Palliation): What makes the pain worse? What makes the pain better? This could be things like medication, rest, heat, ice, or a certain position.
  • Q (Quality): What is the quality of the pain? Is it burning, dull, sharp, constant, aching etc?
  • R (Radiation): Does the pain radiate to other areas of the body?
  • S (Severity): What is the severity of the pain?
  • T (Timing): How long has the pain lasted? Is it getting better, worse, or staying the same?

Pain Interventions

While it may seem like the first treatment for pain in the clinical setting is opioid medication, successful pain management actually involves a multifaceted approach. 

Opioid medications include morphine, fentanyl, hydromorphone, hydrocodone and oxycodone (among others). Opioids are generally utilized to treat moderate to severe pain such as post-operative pain, the pain associated with a myocardial infarction, and cancer-related pain. Common adverse effects of opioids include respiratory depression, constipation, orthostatic hypotension and sedation. If a patient becomes over-sedated with opioids and has respiratory depression, the reversal agent is naloxone. Note that the effects of naloxone may not last as long as the opioid effects, and re-sedation is possible. Patients who receive naloxone must be monitored closely for at least two hours after administration to ensure they do not experience respiratory depression once the naloxone dose wears off. 

Non-opioid pain medications include acetaminophen and NSAIDS such as ibuprofen and ketorolac. They are utilized to treat mild to moderate pain, and may also be used in coordination with opioid analgesics for more severe pain. 

Acetaminophen can cause hepatotoxicity and in the clinical setting healthy individuals are limited to 3 to 4 grams per day. A key teaching point is to ensure patients understand that hydrocodone contains acetaminophen and that taking too much not only puts them at risk for respiratory depression from the opioid component, but that liver toxicity is possible due to the acetaminophen component.

NSAIDs can cause gastric bleeding with sustained use as well as hypertension and renal impairment. They are generally used to treat pain associated with inflammation such as muscle aches or inflammatory arthritis, but they are also used post-operatively in some cases where bleeding risk is not significant. A commonly used postoperative NSAID is IV/IM ketorolac, but note it can cause gastric irritation, renal failure, gastric ulcers, and bleeding, especially if its use extends beyond five days.

Adjuvant analgesics are medications that have a primary clinical use other than pain but are used as analgesics in some cases. They may be utilized as monotherapy for certain types of chronic pain, as an enhancement for opioids so that less opioids are used, or to address symptoms that exacerbate pain such as anxiety, inflammation and depression. 

  • Skeletal muscle relaxants such as baclofen and cyclobenzaprine are primarily used to treat muscle spasticity but also have beneficial effects in many types of neuropathic pain. 
  • Antidepressants such as amitriptyline, a tricyclic antidepressant and duloxetine, an SNRI. These medications are used to address chronic pain including back pain, fibromyalgia and neuropathic pain.
  • Anticonvulsants such as carbamazepine and gabapentin. Gabapentin is commonly used to treat pain associated with postherpetic neuralgia and diabetic neuropathy, and it does this by changing the way the body senses pain.
  • Corticosteroids decrease pain by reducing inflammation, edema and nerve depolarization which make them effective adjuvants for bone pain, visceral pain and neuropathic pain.
  • Bisphosphonates may be utilized to lessen bone pain associated with some types of cancer.
  • Antihistamines such as hydroxyzine and diphenhydramine can reduce anxiety associated with pain and may help muscular pain as well.
  • Anti-anxiety medications such as diazepam are used to treat pain associated with muscle spasm.
  • Botulinum toxin (Botox) is a local medication that relieves muscle spasticity, which can contribute to migraine headaches. 

Nonpharmacologic Pain Management

There are a lot of possible pain management therapies that are nonpharmacologic in nature. Some of the most commonly used at the bedside are heat, cold, distraction and positioning.

Heat is utilized to improve blood flow, relax muscles and reduce stiffness, while cold is used to decrease inflammation. The general rule of thumb with heat and cold therapy is not to exceed about 20 minutes at a time and to watch the skin carefully for injury. 

Distraction can be an effective way to address mild to moderate pain and includes things like watching television, talking with a visitor, ambulating or playing a game. Positioning is an easy and often overlooked method for lessening pain. Simply elevating the affected extremity on two or three pillows reduces edema and the additional pressure against nerve tissue. For patients with chronic pain, always ask them what position or other interventions help their pain…they definitely know best!

Another nonpharmacologic pain therapy you may see utilized for chronic pain is transcutaneous electrical nerve stimulation (TENS). The TENS device utilizes small electrodes that emit electric signals that blocs pain messages from being sent to the brain and changes how the individual perceives pain. 

Patient Controlled Analgesia (PCA)

With patient-controlled analgesia, the patient is in control of when they receive pain medication via a system that enables them to self-administer safe doses of opioids such as morphine. 

Some key things to know about patient controlled analgesia are: 

  • The medication may be dosed as intermittent boluses only, or the physician may also prescribe a basal dose that runs continuously at a low rate. Always read medication orders carefully and double-check them with another nurse prior to administration.
  • Only the patient should press the button to deliver a dose. Teach visitors not to press the button for the patient as this could cause oversedation and respiratory depression. 
  • Monitor patients closely for oversedation and respiratory depression, especially when the PCA has a basal dose in addition to self-administered doses. If the patient becomes overly sedated or has respiratory depression, let the MD know immediately and anticipate a lowering of the PCA dose. If emergent reversal is needed, the medication utilized is naloxone.
  • Patients with a PCA should be on continuous pulse oximetry monitoring, and some  hospitals require supplemental oxygen at least 2L NC to prevent hypoxia. 

Pro tip! Never forget to reassess pain after performing an intervention or giving a medication. Reassess pain one hour after giving PO pain medications and about 15 minutes after administering IV medication. If you are applying heat, using an ice pack, or helping the patient to find a more comfortable position, give the intervention a few minutes to take effect before reassessment. It may take some trial and error, but with patience and practice your ability to treat pain in a variety of ways will improve.

Has this brief overview of pain helped you understand this important fundamental concept? Explore more nursing fundamentals here.

You can review basics of pain again while you’re on the go in episode 309 of the Straight A Nursing podcast. Tune in wherever you get your podcast fix, or straight from the website here.


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