Pain Management -03-07 Version

By: Mayla Lerias Saba, R.N., M.D.

A look at pain Pain is a complex, subjective phenomenon that involves biological, psychological, cultural, and social factors to put it succinctly, pain is whatever the patient says it is, and it occurs whenever she says it does. The only true authority on any given pain is the person experiencing it.

Pain thresholds and tolerances vary. Pain threshold is a physiologic attribute that denotes the intensity of the stimulus needed to sense pain. Pain tolerance is a psychological attribute that describes the amount of stimulus ( duration and intensity) that the patient can endure before stating that she’s in pain. Theories about pain Specificity Pattern Gate control

Let’s get specific The specificity theory maintains that individual specialized peripheral nerve fibers are responsible for pain transmission. This biologically oriented theory doesn’t explain pain tolerance, nor does it allow for social, cultural, or empirical factors that influence pain.

Pain Pattern The pattern theory suggest that excessive stimulation of all nerve endings produces a unique pattern interpreted by the cerebral cortex as pain. Although this theory addresses the brain’s ability to determine the amount, intensity, and type of sensory input, it doesn’t address no biological influences on pain perception and transmission.

Opening the gate The gate control theory asserts that some sort of gate mechanism in the spinal cord allows nerve fibers to receive pain sensations. (See Understanding the gate control theory.) This theory has encourage a more holistic approach to pain management and research by talking into account the no biological components of pain. Pain management techniques, such as cutaneous stimulation, distraction, and acupuncture are, in part, based on this theory.

Types of pain There are two fundamental pain types acute and chronic. Acute Pain Acute pain commonly accompanies tissue damage from injury or disease. It varies from mild to serve in intensity and typically lasts for a brief period (less than 6 months). Acute pain is considered a protective mechanism, alerting the individual to tissue damage or organ disease as the underlying disorder heals.

Relief and healing Treatment goals for acute pain include relieving pain and healing the underlying injury or disease responsible for the pain. Palliative treatment may include surgery, drug therapy, application of heat or cold, or psychological and behavioral techniques to control pain.

Understanding the gate control theory Intensive research into the pathophysiology of pain has yielded several theories about pain perception, including the MelzackWall gate control theory. According to this theory, pain and thermal impulses travel along smalldiameter, slow-conducting afferent nerve fibers to the spinal cord’s dorsal horns. There, they terminate in an area of gray matter called the substantia gelatinosa.

Open or close the gate When sensory stimulation reaches a critical level, a theoretical “gate” in the substantia gelatinosa opens, allowing nearby transmission cells to send the pain impulse to the brain along the interspinal neurons to the spinothalamic tract, and then to the thamalus and cerebral cortex (see illustration below, left). The small sizes of the fibers enhances pain transmission. In contrast, large-diameter fibers inhibit pain transmission Stimulation of these large, fast-conducting afferent nerve fibers counters the input of the smaller fibers, thereby closing the theoretical gate in the substantia gelatinosa and blocking the pain transmission (see illustration below, rigth).

Keys to the gate Descending (efferent) impulses along various tracts from the brain and brain stem can enhance or reduce pain transmission at the gate. For example, triggering specific brain processes, such as attention, emotions, and memory of pain, can intensity pain by opening the gate.  

Chronic pain The cause or chronic pain isn’t always clear. Chronic pain can stem from prolonged disease or dysfunction, as in cancer and arthritis, or it can be associated with a mental disorder such as posttraumatic stress syndrome. It can be intermittent, limited, or persistent and usually 6 months or longer. This type of pain is strongly influenced by the patient emotions and environment.

There are three categories of chronic pain: 1 chronic nonmalignant pain, such as the pain associated with nonprogressive or healed tissue injury 2 chronic malignant pain, such as the pain associated with cancer or other progressive disorder 3 chronic intractable pain, such as the pain that increases as the patient ability to cope deteriorates

Not the pain next door Chronic pain isn’t always localized which makes difficult at times for the patient to clearly describe what he feeling. Furthermore, a patient with chronic pain reacts in different ways, making it difficult for the health care professionals to assess the pain. One patient may cry out, one may groan and still another may simply withdraw. Changes in appetite, sleeping patty can be important clues into the nature of the

Have a stable day Treat for chronic pain focuses on reducing or eliminating the patient pain while improving, or at least stabilizing, his ability to conduct daily activities. It also attempts to reduce the patient need for medication. In mild chronic pain Treatment might simply involve ice massage and exercise. However, severe chronic pain typically requires a multidisciplinary program to address the physiological, psychological, and social component of the patient’s condition

Assessing pain The only way to get an accurate understanding of the patient’s pain is to ask him. Begin by asking the patient’s to describe his pain Where does it hurt? What exactly does it feel like? When does it start, how long does it last, and how often does it recur? What provokes it? What makes it feel better? There are a variety of assessment tools that can help. Encourage the patient to use one to obtain a more accurate and consistent description of pain intensity and relief two important measurements.

Where does it hurt Find out how the patient responds to pain. Does his pain interfere with eating? Sleeping? Working? His sex life? His relationship? Ask the patient to point to the area where he feels pain, keeping in mind That Localized pain is felt only at its origin Projected pain travel along the nerve pathways Radiated pain extend in several direction from the site of origin. Referred pain occurs in places remote from the site of origin.

Nature’s Source Factors that influence the nature of patient’s pain include duration, severity and source. The source may be: Cutaneous, originating in the skin or subcutaneous tissue Deep somatic, which include nerve, bone, muscle, and supporting tissue Visceral, which include the body organs. Watch for physiological responses to pain (nausea, Vomiting changes in vital signs) and behavioral responses to pain (facial expression, movement and positioning, what the patient say or doesn’t say). Also note psychological responses, such as anger, depression, and irritability.

About attitude Assess the patient’s attitude about pain. Ask him how he usually handles pain. Does he tell other when he hurt, or does he try to hide it? Does his family understand his pain and try to help him deal with it? Does he accept their help?

Pain Assessment tools Several easy-to-use tools can help you better understand the patient’s pain. A rating scale is a quick method of determining the patient’s perception of pain intensity. Ask him to rate his pain on a scale from 1 to 10. With 1 representing pain-free and 10 representing the most pain imaginable.

A face rating scale uses illustrations of five or more faces with expressions that range from happy to very unhappy. The patient chooses the face that represents how he feels at the moment. It's particularly useful with a young child or a patient with language difficulty.

A body diagram allows the patient to draw the location and radiation of pain on an illustration of the body A questionnaire provides the patient with key question about the pain’s location, intensity, quality, onset, and aggravate pain.

A questionnaire provides the patient with key question about the pain’s location, intensity, quality, onset, and aggravate pain.

Managing pain Pain management can involve drug therapy with opioid or nonopioid analgesic, including patient controlled analgesic (PCA) and adjuvant analgesic, neurosurgery; transcutaneous electrical nerve stimulation (TENS) and cognitive behavioral strategies

 Opioid

analgesics

Opioid analgesics are prescribed to relieve moderate to serve pain They include opiates and opioid. Opiates are natural opium alkaloids and their derivatives, opioid are synthetic compound but can also include opiates. Morphine is the prototype for both types of opioid analgesic

The agony and the ecstasy Opioid analgesics are classified as agonists or agonists-antagonists. Agonists are drugs that produce analgesia by binding to central nervous system (CNS) opiate receptors. These drugs are the drugs of choice for severe chronic pain. They include:  Codeine  Hydromorphone  Levorphanol  Meperidine  Methadone  Morphine  Propoxyphene

Up the anti Agonists-antagonists also produce analgesia by binding to CNS receptors. However, they’re of limited use for patients with chronic pain because many have a ceiling effect or upper dosing limit. As the dosage increases, they also can cause hallucinations and other psychotomimetic effects and, in opioid-dependent patients, can produce withdrawal symptoms. This class of drugs includes:  Buprenorphine  Butorphanol  Nalbuphine  Pentazocine

Caution is the key Opioids can produce severe adverse effects; therefore, caution is the key. They’re contraindicated in patients with severe respiratory depression and should be used cautiously in patients with: Chronic obstructive pulmonary disease Hepatic or renal impairment, because they’re metabolized by the liver and excreted by the kidneys Head injuries or any conditions that raises intracranial pressure (ICP) because they increase ICP and can induce miosis (which can mask pupil dilation, an indicator of increased

 

Monitoring Before giving an opioid analgesic, make sure the patient isn’t already taking a CNS depressant such as barbiturate. Concurrent use of another CNS depressant enhances drowsiness, sedation, and disorientation. During administration, check the patient’s vital signs and watch for respiratory depression. If his respiratory rate declines to 10 breaths/minute or less, call his name, touch him, and tell him to breathe deeply. If he can’t be aroused of if he’s confused or restless, notify the doctor and prepare to administer oxygen. If ordered, administer an opioid antagonist such as naloxone.

Understanding patient-controlled analgesia A patient controlled analgesia (PCA) system provides optimal opioid dosing while maintaining a constant serum concentration of the drug. How it works? A PCA system consists of a syringe injection pump piggybacked into an I.V. or subcutaneous infusion port. When the patient presses a button, he receives a preset bolus dose of medication. The doctor programs the bolus dose and the “lock-out” time between boluses, thus preventing overdose. The device automatically records the number of times the patient presses the button, helping the doctor adjust the dosage.

In some cases, the PCA system allows a reduction in drug dosage, possibly because the patient feels more control over his pain relief and knows that, if he’s in pain, analgesia is quickly available. This tends to reduce the patient’s level of stress and anxiety which can exacerbate pain.

Patient teaching Teach the patient About his drug therapy and ways to avoid or resolve adverse effects. Tell him to:  Take the prescribed drug before the pain becomes intense

to maximize its effectiveness and talk with the doctor if the drug seems less effective over time.  Not increase the dose or frequency of administration and take a missed dose as soon as he remembers, while maintaining the interval between doses.  Skip the missed dose if it’s just about time for the next dose to avoid serious complications of double dose.  Refrain from drinking alcohol while taking the drug to avoid pronounced CNS depression.  Talk with his doctor if he decides to stop taking the drug because the doctor can suggest an appropriate gradual dosage reduction to avoid withdrawal symptoms.  Avoid postural hypotension by getting up slowly when getting out of bed or a chair.  Eat a high-fiber diet, drink plenty of fluids, and takes a stool softener, if prescribed.

Nonopioid analgesics Nonopioid analgesics are prescribed to manage mild to moderate pain. When used with an opioid analgesic, they help relieve moderate to severe pain and also allow lower dosing of the opioid agent. These drugs include acetaminophen and NSAIDs, such as aspirin, ibuprofen, indomethacin, naproxen, naproxen sodium, phenylbutazon, and sulindac.

  Special effects NSAIDs and acetaminophen produce antipyretic and analgesic effects. In addition, as their name suggest, NSAIDs have an anti inflammatory effect. Because these drugs all differ in chemical structure, they vary in their onset of action, duration or effect, and method of metabolism and excretion. In most cases, the analgesic regimen includes a nonopiod drug even if the patient’s pain is severe enough to warrant treatment with an opiod. They’re commonly used to treat postoperative and postpartum pain, headache, myalgia, arthralgia, dysmenorrheal, and cancer pain.

Not so special effects The chief adverse effects of NSAIDs include: inhibited platelet aggregation (rebounds when drug is stopped) GI irritation Hepatotoxicity Nephrotoxicity Headache Liver damage (in long-term, high-dose use).

NSAIDs shouldn’t be used in patients with aspirin sensitivity, especially those with allergies, asthma, and aspirin-induced nasal polyps, due to the increased risk of bronchoconstriction or anaphylaxis. Also, NSAIDs are contraindicated in patients with thrombocytiopenia, and should be used cautiously in neutropenic patients because antipyretic activity may mask the only sign of infection. Some NSAIDs are contraindicated in patients with renal dysfunction, hypertension, GI inflammation, or ulcers.

Before administering nonopioid analgesics, check the patient’s history for a previous hypersensitivity reaction, which may indicate hypersensitivity to a related drug in this group. If the patient is already talking an NSAID, ask him if he has experienced GI irritation. If he has, the doctor may choose to reduce the dosage or discontinue the drug. If the patient is undergoing long-term therapy, report any abnormalities in renal and liver function studies. Also, monitor hematologic studies and evaluate complaints of nausea or gastric burning. Watch for sign or iron deficiency anemia, such as pallor unusual fatigue, and

Patient teaching For patient talking and NSAID, teach him the signs and symptoms of overdose, hypersensitivity, and GI bleeding, such as rash, dyspnea, confusion, blurred vision, nausea, bloody vomitus, and black, tarry stools. Tell him to report any of these signs to his doctor immediately. If the patient is talking acetaminophen, teach him that nausea, vomiting, abdominal cramps, or diarrhea may indicate an overdose and that he should notify his doctor immediately.

Neurosurgery Neurosurgery is an extreme form of pain management and is rarely needed. However , there are a number of procedures, such as rhizotomy and cordotomy, that can control pain by surgically modifying critical points in the nervous system. (see surgical intervention for pain,)

 

Surgical intervention for pain Surgery is typically considered to manage pain only when pharmacologic therapies fail. More and more however, these techniques are being used earlier with excellent effect. Surgical procedures used to treat pain include neurectomy, rhizotomy, cordotomy, cryoanalgesia, and radio frequency lesioning.

Neurectomy involves resection or partial or total excision of a spinal or cranial nerve. This procedure is relatively quick and only requires local or regional anesthesia. Unfortunately. Loss of motor sensation is a possible adverse effect, and pain relief may only be temporary, peripheral neurectomy is consider when all standard pain management therapies have failed.

Rhizotomy involves cutting a nerve to relief pain. Rhizotomy of the dorsal nerve root may produced analgesia for localized severe pain, such as on the trunk, abdomen, or limb. Motor function is usually unaffected if one dorsal nerve root for the area is left intact.  

Cordotomy can be performed as an open surgery or percutaneously. A unilateral cordotomy is performed to relieve somatic pain on one side of the body. A bilateral cordotomy is performed to relieve visceral pain on both sides of the body.

Cryoanalgesia deactivates a nerve using a cooled probe that cause temporary nerve injury. Nerve function returns over time and the procedure can be repeated. Cryoanalgesia can provide pain relief for the patient with pain from a surgical scar, a neuroma trapped in scar tissue, and occipital neuralgia.

Radio-frequency lesioning Radio-frequency lesioning may affect the nerve from heat generated, the magnetic field created by the radio waves, or both nerve function is stopped for a prolonged period. If it does return, the procedure can be repeated. The most frequent use of this technology is to retreat pain related to the facet joint and lumbar sympathetic and peripheral nerves. Because it’s a focused therapy. It’s used when specific nerves can be targeted.

Tens Tens relieves acute and chronic pain by using a mild electrical current that stimulates nerve fibers to block the transmission of pain impulses to the brain. The current is delivered through electrodes placed on the skin at points determined to be related to the pain. TENS is used to treat:

 Chronic back pain  Postoperative pain  Dental pain  Labor pain  Pain from peripheral neuropathy or nerve injury  Postherpetic neuralgia  Reflex sympathetic dystrophy  Musculoskeletal trauma  Arthritis  Phantom limb pain.

  TENS is contraindicated if the patient has a pacemaker. The current may also interfere with electrocardiography or cardiac monitoring. Furthermore, TENS shouldn’t be used when the etiology of the pain is unknown because it might mask a new pathology.

Asses the patient for signs of excessive or inadequate stimulation. Muscle twitching may indicate overstimulation, whereas an inability to feel any tingling sensation may mean that the current is too low. If the patient complaints of pain or intolerable paresthesia, check the settings, connections, and electrode placements. Adjust the settings if necessesary. If you must relocate the electrodes during treatment, first turn off the TENS unit. Evaluate the patient’s response to each TENS treatment and compare the results. Also, use your baseline assessment evaluate the effectiveness of the procedure.

If the patient will use the TENS unit at home, have him demonstrate the procedure, including electrode placement, the settings of the unit’s control, electrode removal, and proper care of the equipment. Explain that he should strictly follow the prescribed settings and electrode placement. Warm against using high voltage, which can increase pain, or using the unit to treat pain for which he doesn’t know the cause. Also tell the patient to notify the doctor if pain worsens or develops at another site.

Behavior modification and relaxation techniques may be used to help the patient reduce the suffering associated with pain. These techniques included biofeedback, distraction. Guided imagery, hypnosis, and meditation. These “mind-over-pain” techniques allow the patient to exercise a degree of control over his pain. In addition, they have the added benefit of being virtually risk-free with few contraindications. Even so, if the patient has a significant psychiatric problem, a psychotherapist should teach him the relaxation techniques