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MEDSURG: CHAPTER 12: PAIN MANAGEMENT:

Terms in this set (71)

- Prostaglandins are lipid compounds that initiate inflammatory responses that increase tissue swelling and pain at the site of injury
- They form when the enzyme phospholipase breaks down phospholipids into arachidonic acid.
- In turn, the enzyme cyclo-oxygenase (COX) acts on arachidonic acid to produce prostaglandins
- COX-1 and COX-2 are isoenzymes of COX and play an important role in producing the effects of the nonopioid analgesic agents, which include the nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen (Tylenol).
- NSAIDs produce pain relief primarily by blocking the formation of prostaglandins in the periphery
- The nonselective NSAIDs, such as ibuprofen (Motrin, Advil), naproxen (Naprosyn), diclofenac (Voltaren), and ketorolac (Toradol), inhibit both COX-1 and COX-2, and the COX-2 selective NSAIDs, such as celecoxib (Celebrex), inhibit only COX-2.
- Both types of NSAIDs produce anti-inflammation and pain relief through the inhibition of COX-2.
- Acetaminophen is known to be a COX inhibitor that has minimal peripheral effect, is not anti-inflammatory, and can both relieve pain and reduce fever by preventing the formation of prostaglandins in the CNS
- Other analgesic agents work at the site of transduction by affecting the flux of ions.
- For example, sodium channels are closed and inactive at rest but undergo changes in response to nerve membrane depolarization.
- Transient channel opening leads to an influx of sodium that results in nerve conduction
- Local anesthetics reduce nerve conduction by blocking sodium channels.
- Anticonvulsants also produce pain relief by reducing the flux of other ions, such as calcium and potassium
- Transmission is another process involved in nociception.
- Effective transduction generates an action potential that is transmitted along the A-delta (δ) and C fibers
- A-δ fibers are lightly myelinated and faster conducting than the unmyelinated C fibers
- The endings of A-δ fibers detect thermal and mechanical injury, allow relatively quick localization of pain, and are responsible for a rapid reflex withdrawal from the painful stimulus.
- Unmyelinated C fibers are slow impulse conductors and respond to mechanical, thermal, and chemical stimuli.
- They produce poorly localized and often aching or burning pain. A-beta (β) fibers are the largest of the fibers and respond to touch, movement, and vibration but do not normally transmit pain
- Noxious information passes through the dorsal root ganglia and synapses in the dorsal horn of the spinal cord.
- An action potential is generated, and the impulse ascends up to the spinal cord and transmits the information to the brain, where pain is perceived.
- Extensive modulation occurs in the dorsal horn via complex neurochemical mechanisms
- The primary A-δ fibers and C fibers release various transmitters including glutamate, neurokinins, and substance P.
- Glutamate is a key neurotransmitter because it binds to the N-methyl-D-aspartate (NMDA) receptor and promotes pain transmission.
- The drug ketamine, an NMDA receptor antagonist, produces analgesia by preventing glutamate from binding to the NMDA receptor sites.
- Endogenous and exogenous (therapeutically given) opioids bind to opioid receptor sites in the dorsal horn to block substance P and thereby produce analgesia
- The opioid methadone (Dolophine) binds to opioid receptor sites and has NMDA antagonist properties
- Patient-controlled analgesia (PCA) is an interactive method of pain management that allows patients to treat their pain by self-administering doses of analgesic agents.
- It is used to manage all types of pain by multiple routes of administration, including oral, IV, subcutaneous, epidural, and perineural
-. A PCA infusion device is programmed so that the patient can press a button (pendant) to self-administer a dose of an analgesic agent (PCA dose) at a set time interval (demand or lockout) as needed.
- Patients who use PCAs must be able to understand the relationships between pain, pushing the PCA button or taking the analgesic agent, and pain relief and must be cognitively and physically able to use any equipment that is utilized to administer the therapy.
- The use of a basal rate (continuous infusion) is commonly used for opioid tolerant patients and when PCEA is used. It is sometimes used for patients who are opioid naïve and receiving IV PCA to allow them to manage their pain and rest better. However, it is important to recognize that the patient has no control over the delivery of a continuous infusion.
- Therefore, extreme caution in using basal rates for acute pain management in opioid-naïve individuals is recommended
- Essential to the safe use of a basal rate with PCA is close monitoring by nurses of sedation and respiratory status and prompt decreases in opioid dose (e.g., discontinue basal rate) if increased sedation is detected
- The primary benefit of PCA is that it recognizes that only the patient can feel the pain and only the patient knows how much analgesic will relieve it.
- This reinforces that PCA is for patient use only and that unauthorized activation of the PCA button (PCA by proxy) should be discouraged
- For some patients who are candidates for PCA but unable to use the PCA equipment, the nurse or a capable family member may be authorized to manage the patient's pain using PCA equipment.
- This is referred to as Authorized Agent Controlled Analgesia; guidelines are available for the safe administration of this therapy
- Lidocaine patch 5%

- Local anesthetics have a long history of safe and effective use for all types of pain management.
- Local anesthetics are sodium channel blockers that affect the formation and propagation of action potentials.
- They are given by various routes of administration and are generally well tolerated by most individuals
- Injectable and topical local anesthetics are commonly used for procedural pain treatment.
- Local anesthetics are added to opioid analgesic agents and other agents to be given intraspinally for the treatment of both acute and chronic pain.
- They are also infused for continuous peripheral nerve blocks, primarily after surgery.
- The lidocaine patch 5% (Lidoderm) is placed directly over or adjacent to the painful area for absorption into the tissues directly below.
- The drug produces minimal systemic absorption and adverse effects.
- The patch is left in place for 12 hours and then removed for 12 hours (12 hours on, 12 hours off regimen).
- This application process is repeated as needed for continuous analgesia.
- The drug is approved for the neuropathic pain syndrome postherpetic neuralgia; however, research suggests that it is effective and safe for a wide variety of acute and chronic pain conditions
- Allergy to local anesthetics is rare, and adverse effects are dose related. CNS signs of systemic toxicity include ringing in the ears, metallic taste, irritability, and seizures.
- Signs of cardiotoxicity include circumoral tingling and numbness, bradycardia, cardiac dysrhythmias, and CV collapse
- Most individuals use self-management strategies to deal with their health issues and promote well-being.
- Recent national health survey results reveal that American adults spent $14.9 billion on complementary health practices (e.g., acupuncture, chiropractic manipulation, herbal medicines) to treat painful conditions (e.g., back pain, fibromyalgia, arthritis)
- Non-pharmacologic complementary and alternative interventions include using natural products (e.g., herbs or botanicals, vitamins, probiotics) or using mind and body practices (e.g., acupuncture, chiropractic manipulation, massage therapy, yoga, tai chi)
- Non-pharmacologic therapies are usually effective alone for mild to some moderate-intensity pain, and they should complement, but not replace, pharmacologic therapies for more severe pain
- The effectiveness of nonpharmacologic methods can be unpredictable, and although not all will relieve pain, they offer many benefits to patients with pain.
- For example, research suggests that non-pharmacologic methods can facilitate relaxation and reduce anxiety and stress
- Many patients find that the use of non-pharmacologic methods helps them cope better with their pain and feel greater control over the pain experience.
- Several non-pharmacologic methods can be used in the clinical setting to provide comfort and pain relief for all types of pain; however, time is often limited in this setting for implementation of these methods.
- Nurses play an important role in providing them and instructing patients about their use
- Many of the methods are relatively easy for nurses to incorporate into daily clinical practice and may be used individually or in combination with other non-pharmacologic therapies.