Pain Management Nursing Exam

This content sits in Domain I, Fundamentals of Pain, subdomain A, Science of Pain. Domain I carries about 44% of the scored items on the PMGT-BC exam (55 of 125), and Science of Pain is split between this section and Section 2. ANCC rarely asks you to recite physiology for its own sake. Instead, a stem describes a patient's words ("burning," "like an electric shock," "a deep ache I cannot pinpoint") and asks you to classify the pain, choose the drug class most likely to help, explain why a therapy works, or recognize that rising opioid doses are making pain worse. Expect applied questions in which mechanism drives the nursing action.

This chapter covers the clinical and scientific definitions of pain, the classification of pain by mechanism and by duration, and the special categories of cancer pain and breakthrough pain. Correct classification is the first step toward choosing the right multimodal plan.

The International Association for the Study of Pain (IASP) describes pain as an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. Key implications: pain is always both sensory and emotional, it can exist without identifiable tissue damage, a person's report deserves respect even when no cause is found, and inability to communicate does not mean a person is not in pain.

The clinical definition taught by Pasero and McCaffery states that pain is whatever the person experiencing it says it is, existing whenever the person says it does. This principle makes the patient's self-report the gold standard of assessment. It does not mean the nurse stops thinking: the nurse still assesses sedation, function, behavior and safety, but does not discount the report because vital signs are normal, the patient is smiling, sleeping, using a phone, or has a history of substance use.

Nociception is the neural process of encoding a noxious stimulus. Pain is the conscious experience. The two can be separated: nociception without pain occurs under general anesthesia, and pain without ongoing nociception occurs in phantom limb pain and nociplastic conditions.

Pain is classified by its underlying mechanism because mechanism predicts which treatments work.

Nociceptive pain arises from actual or threatened damage to non-neural tissue and activation of intact nociceptors. It has two subtypes. Somatic pain comes from skin, muscle, bone, joints and connective tissue; it is well localized and described as aching, throbbing, sharp or stabbing. Examples include incision pain, fractures, osteoarthritis and bone metastases. Visceral pain comes from organs; it is poorly localized, diffuse, cramping, squeezing or pressure-like, often accompanied by nausea, sweating and blood pressure changes, and frequently referred to distant skin areas (cardiac pain to the left arm or jaw, gallbladder pain to the right shoulder, pancreatic pain to the back). Visceral nociceptors respond to stretch, distension, ischemia and inflammation rather than cutting.

Neuropathic pain is caused by a lesion or disease of the somatosensory nervous system. It may be peripheral (postherpetic neuralgia, diabetic neuropathy, chemotherapy-induced neuropathy, radiculopathy, nerve injury) or central (post-stroke pain, spinal cord injury, multiple sclerosis). Patients describe burning, shooting, electric shock-like, stabbing, tingling, pins and needles, or numbness. Key exam terms include allodynia (pain from a stimulus that normally does not cause pain, such as bedsheets or light touch), hyperalgesia (an exaggerated response to a stimulus that normally hurts), paresthesia (an abnormal but not unpleasant sensation) and dysesthesia (an unpleasant abnormal sensation). Neuropathic pain responds poorly to opioids alone and better to adjuvants such as gabapentinoids, SNRIs, TCAs and topical lidocaine or capsaicin.

Nociplastic pain arises from altered nociception without clear evidence of actual or threatened tissue damage activating nociceptors and without evidence of disease or lesion of the somatosensory system. It reflects augmented central processing. Examples are fibromyalgia, irritable bowel syndrome, some chronic low back pain, tension-type headache, temporomandibular disorder, interstitial cystitis and chronic primary pain. Pain is often widespread and accompanied by fatigue, unrefreshing sleep, cognitive complaints ("fibro fog") and sensitivity to light, sound or smell. Opioids are not recommended; exercise, CBT, sleep management and centrally acting medications (duloxetine, milnacipran, pregabalin, low-dose amitriptyline) are preferred.

Mixed pain involves more than one mechanism. Cancer pain, chronic low back pain with radiculopathy, and postoperative pain with nerve injury are common examples. Mixed pain is a strong argument for multimodal therapy.

Acute pain has a sudden onset, follows tissue injury such as surgery, trauma or an acute illness, is expected and protective, and resolves as tissue heals. It often produces sympathetic signs (tachycardia, hypertension, diaphoresis, pallor) and observable behaviors such as guarding, grimacing and moaning. Goals are rapid relief, prevention of complications and prevention of transition to chronic pain.

Chronic or persistent pain generally lasts longer than 3 months or persists past the normal time for tissue healing. It no longer serves a protective purpose and is considered a disease in its own right. Many clinicians use the term persistent pain, and the ANCC content outline names acute, chronic and persistent pain. The body adapts physiologically, so vital signs and facial expressions are often normal despite severe pain. Instead, chronic pain shows up as fatigue, sleep disruption, depression, anxiety, withdrawal from activities, reduced function and strained relationships. Goals shift from eliminating pain to improving function and quality of life with a biopsychosocial, interdisciplinary plan.

Recurrent acute pain (such as migraine or sickle cell crises) and acute-on-chronic pain (a patient with chronic back pain who has surgery) are important hybrids. Acute-on-chronic pain usually requires higher analgesic doses than expected because of baseline opioid tolerance and sensitization, plus continuation of the patient's usual regimen to prevent withdrawal.

Cancer pain may be caused by the tumor (bone invasion, nerve compression or infiltration, organ capsule distension, obstruction of a hollow viscus), by treatment (surgery, chemotherapy-induced neuropathy, radiation fibrosis or mucositis), or by unrelated conditions. Most patients with advanced cancer have more than one pain and more than one mechanism. Cancer pain often has a continuous baseline component treated with scheduled, around-the-clock long-acting or regularly dosed medication, plus episodes of breakthrough pain treated with an immediate-release rescue dose. Total pain is common: physical pain is intertwined with fear, grief, financial strain and spiritual questions.

Breakthrough pain is a transient flare of moderate to severe pain occurring on top of otherwise controlled persistent pain. Three types are classically described:

The typical breakthrough dose is an immediate-release opioid of about 10-20% of the 24-hour total opioid dose, offered as often as every 1-2 hours orally or every 15-30 minutes IV per order. If a patient regularly needs more than about 2-3 breakthrough doses a day, the nurse notifies the prescriber so the scheduled dose can be adjusted.

• Pain is a sensory and emotional experience; the patient's self-report is the gold standard.
• Somatic pain is localized and aching, visceral pain is diffuse, cramping and referred, neuropathic pain is burning, shooting or electric, and nociplastic pain is widespread with fatigue and poor sleep.
• Chronic or persistent pain generally lasts longer than 3 months or past healing; vital signs and behaviors adapt and do not rule out pain.
• Breakthrough pain is incident, spontaneous or end-of-dose failure; end-of-dose failure calls for changing the scheduled regimen.
• Breakthrough doses are about 10-20% of the 24-hour opioid total; more than 2-3 rescue doses a day means the prescriber should adjust the basal dose.