Pain Management
Online Course #3004 or #2004 - 5 Contact Hours
Updated 2009


Authors:
Kim Marie Falk, RN, MSN
Peggy M. Goulding, Ph.D.
Shelda L. K. Hudson, RN, BSN, PHN
© National Center of Continuing Education, Inc.

About the Authors

After receiving her BSN from Messiah College, Kim Marie Falk began her registered nursing career as a psychiatric nurse at a specialized psychiatric hospital. A year later she switched to the medical-surgical arena at a community hospital and it was there that she developed a love for oncology. While obtaining her MSN as an oncology advanced practice nurse at the University of Pennsylvania she worked with both hospitalized and hospice patient populations. Upon receiving her MSN she became a clinical instructor for BSN students at Widener University and Holy Family College. After teaching a classroom course at Holy Family College she sought out a full-time teaching position to be able to incorporate both classroom and clinical components to her work. During her years of teaching she has enjoyed incorporating her knowledge and experiences within the psychiatric, medical-surgical, oncology, and hospice fields in order to educate future nurses.

Peggy M. Goulding, Ph.D., received a doctoral degree in educational psychology from the University of Texas at Austin and completed a post-doctoral program in clinical neuropsychology at the University of Houston. She has over twenty years of professional experience in a variety of settings, including state, local and Federal government; private industry; hospitals; rehabilitation facilities; nursing homes; and public and private schools. A former faculty member in neurology at the Saint Louis University School of Medicine, she has also taught at the University of Houston, University of Missouri, and Maryville University.

Shelda L. K. Hudson, RN, BSN, PHN completed her Baccalaureate Degree in Nursing and public health certificate at Azusa Pacific University, and is a member of the International Association of Forensic Nurses (IAFN). She is the Nurse Supervisor of the Instructional Systems Development section of the National Center of Continuing Education. Ms. Hudson has over 18 years of extensive experience in publishing courses in continuing education for healthcare professionals with the National Center.

Purpose and Goals

We, as healthcare professionals, must do our part to provide patients with adequate pain management. One way is through education. This course presents material to educate the healthcare practitioner about pain: its pathophysiology, influencing factors, assessment techniques, and interventions. It also addresses common misconceptions about pain and pain management.

Instructional Objectives

After completing this course the motivated learner should be able to:

• Define pain.
• Name the three nociceptors involved in pain sensation.
• Define pain threshold and pain tolerance.
• List five factors that influence pain perception.
• List four misconceptions that are barriers to pain management.
• Name the parts of the assessment mnemonic PQRST.
• List several physical and behavioral signs and symptoms of pain.
• List the non-opioids, opioids, and adjuvant medications used to treat pain.
• List six non-pharmacologic options for pain management.
• Name three principles of pain treatment.
• Outline current nursing standards for pain management.

Hope for the Univeral Disorder

The You know it at once. It may be the fiery sensation of a burn moments after your finger touches the stove. Or it’s a dull ache above your brow after a day of stress and tension. Or you may recognize it as a sharp pierce in your back after you lift something heavy.
It is PAIN. In its most benign form, it warns us that something isn’t quite right, that we should take medicine or seek a healthcare professiona. At its worst, however, pain robs us of our productivity, our well-being, and, for many suffering from extended illness, their very lives. Pain is a complex perception that differs enormously among individual patients, even those who appear to have identical injuries or illnesses.

A Brief History of Pain

Ancient civilizations recorded on stone tablets accounts of pain and the treatments used: pressure, heat, water, and sun. Early humans related pain to evil, magic, and demons. Relief of pain was the responsibility of sorcerers, shamans, priests, and priestesses, who used herbs, rites, and ceremonies as their treatments.
The Greeks and Romans were the first to advance a theory of sensation, the idea that the brain and nervous system have a role in producing the perception of pain. But it was not until the Middle Ages and well into the Renaissance-the 1400s and 1500s-that evidence began to accumulate in support of these theories. Leonardo da Vinci and his contemporaries came to believe that the brain was the central organ responsible for sensation. Da Vinci also developed the idea that the spinal cord transmits sensations to the brain.
In the 17th and 18th centuries, the study of the body-and the senses-continued to be a source of wonder for the world’s philosophers. In 1664, the French philosopher René Descartes described what to this day is still called a “pain pathway.” Descartes illustrated how particles of fire, in contact with the foot, travel to the brain and he compared pain sensation to the ringing of a bell.
In the 19th century, pain came to dwell under a new domain-science-paving the way for advances in pain therapy. Physician-scientists discovered that opium, morphine, codeine, and cocaine could be used to treat pain. These drugs led to the development of aspirin, to this day the most commonly used pain reliever. Before long, anesthesia-both general and regional-was refined and applied during surgery.
In 1931, the French medical missionary Dr. Albert Schweitzer wrote, “Pain is a more terrible lord of mankind than even death itself.” Today, pain has become the universal disorder, a serious and costly public health issue, and a challenge for family, friends, and health care providers who must give support to the individual suffering from the physical as well as the emotional consequences of pain.
“It has no future but itself,” wrote the 19th century American poet Emily Dickinson, speaking about pain. As the 21st century unfolds, however, advances in pain research are creating hope and a less grim future than that portrayed in Dickinson’s verse, a future that includes a better understanding of pain, along with greatly improved treatments to keep it in check.

Managing pain is a pervasive topic among health care professionals

The Pain is one of the most common reasons people enter the healthcare system; yet it is also one of the most widely under-treated health problems. Untreated and inadequately treated pain causes suffering and financial burden to both patients and society. It is not just pain that is the problem. The side effects of chronic pain illnesses caused by a sedentary lifestyle, seclusion and depression, and sometime addiction to pain killers can be just as devastating as the pain itself. It has a profound effect on the quality of human life.
Pain can cause disruptions in sleep, eating, mobility, and overall ability to function. Progress is being made in understanding the physiological mechanisms involved in pain. However, understanding individuals’ pain experience presents unique scientific challenges. The levels of pain different people experience and their reactions to it vary widely, perhaps due to psychological state, age, gender, social environment, and cultural background, as well as genetic or physiological differences. Thus, the pain experience needs to be examined at all levels of research, with the goal of developing interventions to manage or prevent pain.

Pain is Prevalent

Pathophysiology of Pain

Pain is a term every healthcare practitioner is familiar with, from the professional standpoint as well as through personal experience. However, beyond knowing what pain personally feels like, healthcare practitioners need to know what causes pain and the best ways to manage it in order to give patients excellent care. Though the experience may seem simple - you stub your toe, then you feel pain - pain has been defined in numerous ways.
As a basic scientific definition, pain is a sensation caused by some type of noxious stimulus. From the behavioral aspect, pain is a pattern of responses that function to protect an individual from harm. The International Association for the Study of Pain (IASP) defines pain as "an unpleasant, subjective sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage." Within nursing, one of the most popular definitions has been the one coined by Margo McCaffery: "Pain is whatever the experiencing person says it is, existing whenever he says it does."
Certainly all these definitions describe pain; it is a multi-factorial phenomenon. For the sake of clarity, pain can be divided into two basic components, physical and emotional. From the physical standpoint, almost every tissue found in the human body contains pain receptors, called nociceptors. It has been estimated that the skin may contain as many as 1,300 nociceptors in one square inch. These nociceptors respond to thermal, chemical, and mechanical stimuli through a-delta, C, and a-beta fibers. The a-delta receptors contain small, myelinated fibers that rapidly transmit acute, sharp pain signals from the peripheral nerves to the spinal cord. C receptors have larger, unmyelinated fibers that transmit pain at a slower rate and are commonly associated with long lasting, burning pain sensation. The a-beta receptors respond to non-painful touch, such as a gentle rub or pressure.
Physiologically, both the peripheral and central nervous systems are involved with pain perception. (Figure 1) The peripheral nerve fibers first convey the painful stimuli to the spinal cord. Numerous ascending pathways transmit the stimuli through the dorsal root of a spinal nerve, ending in the dorsal horn of the spinal gray matter. In the substantia gelatinosa, located in the dorsal horn, the stimuli are directed to various parts of the spinal cord. Long nerve fibers, termed spinothalamic axons and spinoreticular axons, cross over to the opposite side of the spinal cord and ascend to the brain in the anterolateral column of the spinal white matter. The interactions between these pathways are complex, involving multiple influences, chemicals, and neurological processes. However, it is this intricate system of neurological processes that enables humans to determine the presence, location, nature, and intensity of pain. Pain perception also involves descending pathways, which have been theorized to be principally involved with pain modulation.
In response to the tissue damage from the noxious stimulus, pain-producing substances are released into the extracellular fluid surrounding the pain fibers. These substances include bradykinin, cholecystokinin, serotonin, histamine, potassium ions, norepinephrine, prostaglandins, leukotrienes, and substance P. The first six chemicals stimulate, whereas the latter three chemicals sensitize the a-delta and C fibers. But the brain and spinal cord also produce pain relieving substances, endorphins and enkephalins. These chemicals attach to endogenous receptors in the brain, spinal cord, and peripheral tissues, activating the descending inhibitory system. The descending opioid-related pain inhibitory system was proposed by Fields and Basbaum and describes several centers in the brain that produce analgesia. The release of endorphins can be triggered by many situations, particularly those entailing stress, fear, or excitement. Aerobic activity can also stimulate endorphins.
From the emotional standpoint, the interconnectedness of thoughts, feelings and beliefs plays a part in pain perception. Research has shown that people experience more pain when they focus on it, are told to expect one thing but experience something different, expect a high level of pain, and are tense and under stress. It has been theorized that structures in the brain are closely involved with the emotional aspects of pain perception. It is believed that stimuli are filtered through the limbic-hypothalamic system and that the frontal cortex influences rational interpretation and response to pain.
Though physical pain reception is a universal human phenomenon, people experience different pain thresholds and tolerances. Pain threshold is the earliest point at which a person perceives stimuli as painful. Most researchers conclude that there is little variation in pain threshold, from person to person and from situation to situation. However, it has been noted that repeated exposure to noxious stimuli can lower a person’s threshold, even if only minimally. This may be due to increased nociceptor sensitivity; when nociceptors are already stimulated less stimulus is needed to produce pain. Pain tolerance refers to the lowest level of stimulation at which a person will stop or seek to stop the stimulus. It is very individualized, different from person to person and from situation to situation.
One theory that attempts to explain both the psychological and physiologic aspects of pain is the Gate Control Theory. (Figure 2) First proposed by Melzack and Wall in 1965, it has undergone numerous modifications, and is still being used today to explain pain. The theory proposes that the transmission of noxious stimuli is modulated by a gating mechanism in the dorsal horn. These theoretical gates can be opened or closed to either allow for or prevent pain transmission. The stimulation of smaller fibers opens the gate; the wider it is opened, the more pain occurs. However, stimulation of large fibers closes the gate, inhibiting pain transmission. It is these large fibers that are thought to selectively activate cognitive processes. The gate can also be closed by messages from higher brain centers; therefore, both ascending and descending systems are involved to control pain impulses and reduce pain intensity.
Pain can be categorized either by its origination or duration. Categories of origin include cutaneous, somatic, visceral, neuropathic, and referred. Cutaneous pain is a direct, acute, and localized sensation activated within the epidermis, dermis, or subcutaneous tissues. A pinprick or paper cut is an example of cutaneous pain. Somatic pain originates from the musculoskeletal system, from structures such as the tendons, ligaments, muscles, joints, bones, blood vessels, and nerves. It is felt as a scattered or diffuse sensation such as the pain experienced by a sprain. Visceral pain is a diffuse, poorly localized feeling emanating from body organs with hollow cavities, such as the cranium, thorax, and abdomen. Appendicitis often causes visceral pain. Neuropathic pain results from damage to either the peripheral or central nervous system. Typically, neuropathic pain is caused by non-noxious stimuli and has a delayed onset. Many people describe neuropathic pain as a burning with periodic stabbing sensations. When pain is felt in a part of the body away from the site of injury it is known as referred pain. Pain can also be categorized in other ways, many of which involve specific sites such as headache and phantom limb.
Pain that is of short duration (less than six months) is called acute; whereas prolonged pain (six months or greater) is termed chronic. However, chronic pain is not necessarily acute pain that has persisted. Most often, the cause of acute pain is known and the course of healing follows a predictable pattern. With chronic pain, treatment does not eradicate the pain, the cause of which may or may not be known. Of importance is that a person experiencing acute pain usually manifests signs and symptoms caused by stimulation of the sympathetic nervous system such as an increase in heart rate, respiratory rate, and blood pressure. However, many people suffering from chronic pain do not demonstrate these objective physical signs but rather experience sleep disturbances, irritability, lack of energy, depression, and even lifestyle or personality changes. Chronic pain can have an insidious onset with characteristics that change over time.

Influencing Factors

Certainly people of all ages are capable of feeling pain. Two particular age groups with special needs include children and older adults. Nonverbal children will not be able to articulate the presence of pain, nor describe its characteristics. The practitioner must be alert to nonverbal cues such as excessive crying, grimacing, and restlessness. Even those children that can speak may have difficulty expressing their feelings. Therefore, the practitioner needs to be very astute when assessing children for the presence of pain.
The other age group with special needs includes the older adult. Many older adults assume that pain is a natural part of aging; this is untrue. What is true is that the incidence of disease and illness increases as we age and pain is a common accompanying symptom. Practitioners need to inquire about and then explore older adults’ areas of pain. Treatment of the diseases and illnesses present is of utmost importance in achieving pain relief.
While studies have been conducted on pain threshold and pain tolerance in relationship to age, many conflicting results have been documented. Considering the elderly, two researchers concluded that pain threshold increases but pain tolerance decreases with age. However, numerous other researchers have criticized studies conducted on older adults’ pain thresholds and tolerances, citing attitudinal bias, delayed reaction times, physical impairments, and cognitive deficits as variables not taken into account. One would suspect that the changes that often accompany aging do affect the pain experience.
In respect to gender, in the American culture men have typically been socialized to deny or conceal their pain, while women are often encouraged to be demonstrative with their reaction to pain. Phrases such as, “Be a big boy and don’t cry” and “You just let it all out now, girl” are part of the American culture. Some researchers have theorized that estrogen is instrumental in regards to modulation of pain sensitivity. Others have demonstrated that the physical and emotional experiences of pain are similar for both genders, while it is the expression that often differs. Nonetheless, very few studies support gender differences in pain threshold. Most scientists believe that social influences, not physical differences, contribute to variations in the pain experience.
Another aspect of culture is the patient’s environment: how he was raised and where he is currently situated. Many professionals are familiar with patients who are more expressive of their pain when family are present and those that remain stoic even in obviously painful situations. When assessing for pain consider factors such as: is the patient generally vocal or quiet and does he seek and trust the healthcare environment? For the patient who is quiet or distrustful of health care, you may need to actively elicit more information and work to establish trust before you can get an accurate pain assessment.
As mentioned earlier, emotional state affects pain. Any additional stressors can aggravate the pain experience. Many times anxiety is also present with pain, causing an increased perception of pain intensity. Other psychological factors affecting pain include fatigue and depression.
Family and social support are usually helpful to patients when dealing with pain. Often patients have their own strong support systems already established and find this helps them to manage the emotional aspect of pain. Sometimes the practitioner needs to assist patients to utilize or even establish support systems. For example, if the patient is agreeable, facilitating visits from family and friends may be necessary. Many people assume that those who experience pain like to be alone but this is not always true, particularly for those that experience chronic or episodic, recurring pain. Studies have shown that when people do not have adequate social support, or perceive insufficient support, they have more complaints of pain and reduced psychological well-being. Formal support groups have been established for many circumstances and nurses can be instrumental in connecting patients to these resources.

Misconceptions

There are many misconceptions among healthcare workers that are barriers to patients receiving adequate pain management. One of the most common and persistent myths is that drug abusers overreact to pain. Many times healthcare workers assume that drug abusers are always seeking to satisfy their addiction and not eliminate actual physical pain. While it is true that part of the drug-abusing syndrome involves drug-seeking behavior, it is also true that people who abuse drugs can experience pain. In fact, changes in the central nervous system related to drug abuse may result in an exaggerated physiologic response to pain stimuli; thus your drug abusing patient may be less tolerant of pain than someone who doesn’t use drugs, and he may be suffering more intensely than the patient in the next bed. As with all people, this pain deserves to be treated effectively. Even though studies have shown that drug abusers tend to need higher doses of pain medicine than the general population due to this tolerance, doctors often prescribe lower doses of narcotics or substitute non-narcotics.
Another misconception lies in the belief that minor illnesses and injuries are less painful than severe ones. However, the amount of tissue damage is not a predictable factor for pain intensity. In fact, when pain receptors are destroyed in a severe injury the patient can experience little or no pain. Additionally, many disorders manifest themselves differently among patients; and each patient can encounter great fluctuations, predictable or unpredictable, in their pain.
One of the most widespread myths among healthcare workers and the general population is that the regular use of analgesics, particularly narcotics, leads to addiction. This belief is rooted in a misunderstanding of the terms tolerance, physical dependence, and addiction. Tolerance is a physical occurrence that will result after repeated administration of a narcotic. A person will need a larger dose of narcotic to gain the same level of pain relief. This is an expected side effect when narcotics are administered over a period of time. Physical dependence is also a physiologic phenomenon that occurs when narcotics are abruptly stopped and the person undergoes a withdrawal syndrome. However, addiction is when a patient’s psychological need for a drug exceeds his physical need. An addicted patient becomes overwhelmingly involved with obtaining and using a drug for its psychic effects. Only a very small minority of patients, less than 1%, actually develops addiction when they are prescribed narcotics for pain. Most often, narcotics are prescribed on a short term basis for severe pain, but their use as appropriate for long term pain, such as in terminal cancer, has been well supported.
Lastly, because pain is subjective, the best authority on the patient’s pain is the patient himself. However, many healthcare workers consider themselves the expert on the patient’s pain. While it is true that healthcare workers often have more knowledge about pain in general, this does not negate the fact that the patient is the only one experiencing the particular pain being treated. This is a very important point to remember when assessing and treating pain. One study of elderly patients’ and nurses’ pain ratings found a significant difference between when nurses and patients thought pain should be treated. Additionally, the nurses tended to underestimate severe pain and overestimate mild pain. This emphasizes the need to continually involve the patient in the treatment process. The most effective treatment occurs when healthcare workers and patients work together to relieve pain.

Assessment

The American Pain Society stresses that clinicians consider pain as the fifth vital sign. This elevates it to an importance given to the measurements of temperature, pulse, blood pressure, and respirations during patient assessments. Unfortunately, inconsistent and incomplete assessments have been cited as major factors contributing to inadequate pain management.
One of the most common mnemonics for remembering the steps involved in pain assessment is PQRST: Provoking factors, Quality, Region/Radiation, Severity/Symptoms, & Timing. Provoking factors include both precipitating and aggravating conditions: what brings the pain on and what makes it worse. This information may lead to the origin of the pain, if unknown, and can also be useful when teaching patients what situations to avoid or modify to help lessen or eliminate the pain. The number of provoking factors is vast and can include certain positions, movements, or activities; specific times of the day or night; and even particular emotions such as anxiety or anger.
To ascertain the quality of the pain the nurse should ask open-ended questions, thus allowing the patient to provide his own description. If the patient is having difficulty, prompts are acceptable and should include common descriptors, for example: sharp, dull, pulling, crushing, throbbing, burning, or pricking. This information can often help determine the pain origin and can be most useful when prescribing or recommending treatment options.
The easiest way to determine the region of pain is to ask the patient to point to or name the specific area or areas on his body. When a patient has diffuse pain, he may indicate a large area or be unable to pinpoint the exact spot. Additionally, those experiencing deep pain, such as visceral pain, may verbally describe the feeling as “deep” or “inside.” Not all pain radiates; but this is a good time to ascertain if radiation is occurring and, particularly when the patient indicates a large area, to clarify if the pain is at the same intensity within the whole area. Remember, radiation is when the pain originates from the injury outward; whereas, referred pain is when the feeling occurs at a site different than the injury. Patients also can experience shifting areas of pain, where certain areas are only periodically painful.
Many tools have been developed to assist the nurse in determining the severity of pain. The use of standardized tools has several advantages. First, they are reliable and objective and thus the most accurate way to rate pain severity. Also, they take very little time and training to implement. Thirdly, the same tools can be used to assess the effectiveness of interventions. The most common tool is the visual analog scale, which features a numerical pain-rating scale. (Figure 3) It uses a 10 cm line with numbers ranging from 0 to 10. Patients point to a number that corresponds to the level of pain they are feeling. Before using the scale with a particular patient the nurse should explain the significance of the numbers: 0 represents no pain, 1-3 mild pain, 4-6 moderate pain, 7-9 severe pain, and 10 means you are experiencing the worst pain imaginable. A variation of the scale often used by health professionals is to describe verbally the 0 to 10 rating and ask the patient to state the corresponding number.
For patients who do not have mastery of the English language or the appropriate cognitive level to use a number scale, the Wong-Baker Faces Pain-Rating Scale is an appropriate alternative (Figure 4) This tool depicts 6 faces ranging from a happy face to a crying grimace. The nurse reads a statement about how each face correlates to pain and then the patient points to the face that best represents how he is feeling.
Besides severity, the “S” in the pneumonic PQRST stands for symptoms. Assess the patient for other symptoms that accompany the pain. Common ones include nausea, vomiting, dizziness, and restlessness. Many times when the patient is given treatment for pain, these symptoms subside or are eradicated; but other times, adjuvant treatments are needed.
The questions to ask in determining timing include: “How long does the pain usually last?” and “When and how does it usually lessen or stop?” The answers to these questions help the nurse to understand the precise nature of the patient’s pain experience and allow the nurse to support the patient’s methods of pain relief, unless they are harmful.
Besides using the PQRST mnemonic, the nurse must be alert for various physical and behavioral signs and symptoms associated with pain or those that may accompany pain. The nurse may observe some of these behavioral indicators, such as restlessness, moaning, crying, clenched teeth, or protecting/guarding body parts. Or the patient may need to state their presence, such as when he is feeling anxious or nauseous. Vital sign changes can also indicate pain, such as an elevation in pulse rate, blood pressure, and respirations. However, this is more accurate for the presence of acute, not chronic, pain. Also, elevated vital signs are not always seen in every acute pain situation, nor are they a reliable indicator of pain intensity. Therefore, the absence of behavioral indicators or vital sign elevations does not mean the patient is not experiencing pain. For example, it is unclear whether a comatose person experiences pain; just because a person cannot respond to a noxious stimulus may not mean that he cannot feel it. Conversely, these other signs and symptoms may be the only clue the nurse has that the patient is in pain. This is particularly significant when the patient has difficulty expressing pain due to factors such as socioculturally learned behaviors, immaturity, neurologic damage, or mental or physical handicap.
Another area for the healthcare professional to observe is how the patient’s pain is affecting activities of daily living (ADLs). When a patient is in pain, ADLs are often either neglected or altered. Sleep can become erratic, sexual activity may decline, exercise programs can cease, playtime or hobbies are neglected and the patient may miss more hours at work. Simply asking patients, “How does pain limit your daily activities?” or “What can you no longer do because of your pain?” may elicit useful information.
Another important area for the healthcare professional to consider when assessing the patient’s pain is neurological status. When deficits are present in the central nervous system, such as dementia, mental handicap, or even immaturity, the nonverbal cues of pain become most important. Though it is more difficult to assess a patient with cognitive impairment, it is not impossible; every person deserves a thorough pain assessment. Behaviors that can indicate pain include flinching, guarding, grimacing, whimpering, and restlessness. Additionally, further investigation is warranted when a patient refuses to move or eat, pulls at equipment such as tubing, or has a change in continence. When the patient has a peripheral nervous system deficit, such as the diabetic with peripheral neuropathy, the sensation of pain in certain parts of the body is altered. Teaching the patient with peripheral nervous system deficits to visually inspect his body on a daily basis is important; injuries can occur without the sensation of pain as a warning. Also, careful application of certain treatments, for example hot or cold packs, is essential.

Pharmacologic Interventions

Once a complete assessment has been done, the patient needs to receive treatment in a timely manner. The key to any treatment plan is individualization, for each patient and sometimes each pain episode. Often a variety of resources are needed for pain control. Certainly the goal is pain eradication, but sometimes bringing pain to an acceptable level of tolerance is more realistic. Pharmacological intervention is usually a good place to start. The three main categories of pharmacologic pain relief medications are non-opioids, opioids, and adjuvants.
Specific examples of commonly used non-opioid pain medications, often called non-narcotics, include acetaminophen, aspirin, nonsteroidal anti-inflammatories (NSAIDs), choline magnesium trisalicylate (Trilisate), and diflunisal (Dolobid). Acetaminophen’s analgesic properties appear to involve central mechanisms associated with nitric oxide and N-methyl-D-aspartate receptors. Aspirin, other salicylates, and NSAIDs inhibit prostaglandin synthesis to produce analgesia.
Common opioid medications, sometimes referred to as narcotics, are typically characterized as either weak or strong. Weak opioids include codeine, oxycodone, Vicodin, and oxycodone combined with either acetaminophen or aspirin. Morphine, hydromorphone, fentanyl, and meperidine are examples of strong narcotic medications. Opioids can also be classified by two subtypes: agonists and agonist-antagonists. Both types of opioids provide analgesia through mu, delta, and kappa receptors found in the central and peripheral nervous systems. The agonists attach to mu, delta, and kappa sites; however, the agonist-antagonists bind to the mu and kappa receptors, producing effects at the kappa sites but blocking effects at the mu sites.
Adjuvant medications can also be used to supplement non-opioid and opioid medications. Adjuvant analgesics are medications whose primary indication is not for pain management but which have demonstrated analgesic effects. Examples of adjuvant medications used to treat pain include tricyclic antidepressants and anticonvulsants. Tricyclic antidepressants help to improve mood and increase pain threshold. The analgesic action of tricyclic antidepressants is not certain; however, it has been theorized that they enhance the descending pain inhibitory system through prevention of serotonin and norepinephrine re-uptake. They have been found to be particularly useful for treating some types of migraines and burning types of pain. Examples of tricyclic antidepressants include amitriptyline and nortriptyline. The anticonvulsants’ mechanism for pain control is also uncertain; however, they have been found to be particularly useful in treating lancinating and neuropathic pain. Carbamazepine, valproate, and gabapentin are three examples of anticonvulsants used to treat pain.
The medication chosen to treat pain is often based on practitioner’s preference; however, certain restrictions apply. Generally, a patient should not be taking two analgesics from the same class at the same time, unless one is sustained release used on a round-the-clock basis and the other is instant release for breakthrough pain. When a patient needs to switch from one narcotic to another, due to ineffectiveness or intolerable side effects, health practitioners should consult an equianalgesic guide. An equianalgesic chart shows practitioners the equivalent potency regarding dosage and route between narcotics, helping to eliminate the possibility of under or overdosing. Educate patients to ask for pain medication when the pain begins, not when it becomes unbearable. Pain control methods work best when they are administered at the onset of pain. Also remember to check patients’ allergies before administering any medication.
In addition to administering medications, nurses are also responsible to know the potential side effects of each medication. Every medication has the potential for side effects, even if the patient has had the medicine before and not experienced a particular side effect. Also, be aware that side effects may occur at lower doses among the older adult population. With the exception of acetaminophen and Trilisate, the non-opioids have antiplatelet effects that can lead to bleeding, particularly in the gastrointestinal tract. Nausea and vomiting have also been associated with the non-opioids. Acetaminophen may cause hepatotoxicity, but this is rarely seen except for overdose or when used with people who have a compromised liver. Be aware that for each non-opioid there is a ceiling dose. The ceiling dose is the highest level of analgesia that can be achieved without significant side effects or toxicity.
The most troublesome side effect of the opioids is constipation. Fortunately, concurrently instituting a bowel regimen usually helps to eliminate this side effect. A good bowel regiment includes the daily use of a stool softener plus a laxative, increasing fiber and fluid intake, and instituting routine aerobic exercises. Opioids can also cause sedation, nausea, and vomiting. As with any sedating medication, caution must be instituted when performing physical activities. An antiemetic can be prescribed for relief of nausea and vomiting. Fortunately, tolerance generally develops to sedation, nausea, and vomiting. Respiratory depression is a potentially serious side effect of opioids but fortunately not a very common one. If respiratory depression does occur, it tends to be a short-lived phenomenon. Additionally, using the antagonist medication naloxone can reverse respiratory depression. However, because the half-life of naloxone is shorter than most opioids, the patient must be monitored closely for recurrence of respiratory depression. Also, using naloxone can reverse the analgesic effects of the opioid; therefore, the patient may need further treatment to control his pain.
Besides the choice of medication, the way a medication is administered is also important. Options include enteral and parenteral medications. Enteral medications are those that use the gastrointestinal (GI) tract, while parenteral medications bypass the GI system. If the GI system is intact, this is usually the best choice. When parenteral medication is preferred there are several notable options: local pain relief, epidurals, rectal administration, and patient controlled anesthesia.
Local pain relief can involve a topical application to the skin or mucous membranes. One popular use of topical pain relief, particularly among the pediatric population, has been the use of a cream mixture of prilocaine and lidocaine applied to the skin before an intravenous insertion is performed.
Another way to administer parenteral medication is through an epidural. An anesthesiologist or anesthetist places a catheter into the epidural space in the spine, securing it with a sterile dressing and tape. Medication is either administered continuously through a pump or intermittently by the anesthesiologist or anesthetist. Usually the catheter placement is temporary and exits out the back; however, long-term epidurals can be performed and they often exit through the abdomen. The nurse’s responsibility to a patient who has an epidural includes making sure the catheter is securely in place, usually taped to the skin, and informing the anesthesiologist or anesthetist when the patient on intermittent dosing needs more medication to be injected into the catheter. Advantages of the epidural route include site-specific, rapid and prolonged pain relief with less severe systemic adverse side effects.
An often neglected route is rectal administration. Advantages of the rectal route include simplicity of administration and lower cost than most other parenteral methods. To administer, position the patient on his left side with top leg flexed, while aiming toward the patient’s umbilicus insert a moistened suppository against the rectal wall approximately a finger’s length into the rectum, and after withdrawing your finger ask the patient to relax and not bear down. Briefly holding the patient’s buttocks together may aid in eliminating expulsion. While suppositories are most often the products given rectally, solutions, injectable medications, and even tablets have been used with little or no alteration. Contraindications of the rectal route include neutropenia (low white blood cell count), thrombocytopenia (low platelets), and rectal bleeding.
Another very effective method of parenteral pain medication administration entails the use of patient controlled anesthesia (PCA). The effectiveness of PCA is based on its individualization, a primary component of pain management. With PCA the patient receives either intravenous or subcutaneous medication when he presses a button on the PCA machine to which he is attached. The nurse, following prescriptive order, presets the medication, dosage, and timing before the patient is attached to the machine. The machine can be set to include a lockout time. This is when the patient can push the button to deliver medication but no medicine is released until a certain time elapses, thus preventing overdose. However, it is very important to monitor patients who are on PCAs, particularly in the initial stage of operation. Areas for potential problems include machinery malfunction, a too strong prescribed dosage, or a too short or too long lockout time. Additionally, patients must be educated on how to use a PCA machine. When a patient is on PCA a nurse should include, as part of the pain assessment, whether the patient understands how PCA works and how to use it to obtain medication. Luckily, PCA machines are easy to use and have the advantage of giving the patient control of his own pain relief. An additional advantage is that patient’s serum drug levels can remain constant since the moment he feels pain, he can push a button to receive medication. When patients rely on nurses for pain medication, relief takes longer since the patient must notify the nurse he is feeling pain, the nurse must check the medication order, then pour the medication, before she can finally give it. An exciting new development is the use of PCA for treating pain in children and adolescents.
A simple, widely used, and effective approach to pharmacotherapy for cancer and other pain hasbeen devised by the World Health Organization (WHO). The five essential concepts in the WHO approach to drug therapy of pain are:

• By the mouth.
• By the clock.
• By the ladder.
• For the individual.
• With attention to detail.

It has been shown to be effective in relieving pain for approximately 90 percent of patients with cancer and over 75 percent of cancer patients who are terminally ill. Called the WHO Pain Ladder, this approach incorporates the concept of an analgesic ladder, a rational, stepwise approach to pain management.
The first step in the ladder is the use of acetaminophen, aspirin, or another NSAID for mild to moderate pain. Adjuvant drugs to enhance analgesic efficacy, treat concurrent symptoms that exacerbate pain, and provide independent analgesic activity for specific types of pain may be used at any step.
When pain persists or increases, an opioid such as codeine or hydrocodone should be added (not substituted) to the NSAID. Opioids at this step are often administered in fixed dose combinations with acetaminophen or aspirin, because this combination provides additive analgesia. Fixed-combination products may be limited by the content of acetaminophen or NSAID, which may produce dose-related toxicity. When higher doses of opioid are necessary, the third step is used. At this step separate dosage forms of the opioid and nonopioid analgesic should be used to avoid exceeding maximally recommended doses of acetaminophen or NSAID.
Pain that is persistent, or moderate to severe at the outset, should be treated by increasing opioid potency or using higher dosages. Drugs such as codeine or hydrocodone are replaced with the more potent opioids (usually morphine, hydromorphone, methadone, fentanyl, or levorphanol), as described above. Medications for persistent cancer-related pain should be administered on an around-the-clock basis, with additional “as-needed” doses, because regularly scheduled dosing maintains a constant level of drug in the body and helps to prevent a recurrence of pain. Patients who have moderate to severe pain when first seen by the clinician should be started at the second or third step of the ladder.
The topic of placebos is controversial. A placebo is any inactive substance given to satisfy a demand for medication. Studies have been done to demonstrate the effectiveness of placebos; however, many healthcare practitioners deem the use of placebos as unethical. Some studies have demonstrated that the effectiveness of placebos may be due to the body’s release of endorphins or even the presence of the healthcare worker. Essentially, when a practitioner prescribes placebos he negates the subjectivity of pain because he has labeled the patient’s pain as not real and therefore, not needing an active treatment. Those patients who are prescribed placebos are often seen as liars, drug seekers, or mentally ill. Certainly, when one prescribes or gives a placebo, there is the potential that the trust relationship, so important within the healthcare arena, could be destroyed.

Non-Pharmacologic Interventions

Besides medications there are also non-pharmacologic options to control pain. Most often they are used to complement pharmacologic options. The advantages of using non-pharmacologic methods include the fact that many of them do not require a prescription or any special equipment. However, always make sure an intervention is appropriate and safe for each patient situation before implementation.
The simplest way to eliminate or reduce pain can involve altering the environment. Many variables within the patient’s setting can cause or worsen pain such as temperature, bedding, body alignment, equipment, and clothing. Adjusting the air-conditioning, adding a fan, or removing or supplying a blanket can help the patient who is uncomfortable due to temperature. Wrinkles in sheets can cause extra friction and pressure, which can be relieved by tightening and smoothing linens. Adding an eggcrate mattress can improve old or unsupportive mattresses. Positioning in anatomical alignment, providing support for limbs, and eliminating pressure points are important ways to prevent pain from occurring in the immobilized patient. Therapeutic beds can also relieve pressure. Encouraging active range-of-motion exercises or providing passive range-of-motion can alleviate pain caused from stiffness and prevent painful muscle contractures. Equipment can cause pressure points and friction areas and therefore must be routinely checked for proper placement, with frequent skin assessments. For example, a nasal cannula can cause erosion of nares or ear tissue, or tubing can become lodged underneath the patient. Also clothing, whether a gown or street clothes, can become bunched up or caught on equipment, causing constriction and pain. Wet clothing can also become an irritant.
Other non-pharmacologic interventions are relaxation and guided imagery, often used together. Relaxation can be as simple as focusing on one’s breathing to control tachypnea or mentally concentrating on a pleasant thought or scene. Patients can also be taught to progressively contract and then relax various muscle groups, usually in a sequential pattern, such as from neck to toes. Meditation is a form of relaxation. Guided imagery generally implies that a trained practitioner reads or speaks in soothing tones while the patient focuses on a positive image, such as a beach scene or a walk in the park. The key points of guided imagery involve focusing on a repetitive thought, word, phrase, or activity and taking a positive attitude toward intruding thoughts, eliminating them as distractions. Relaxation and guided imagery are thought to counterbalance the “fight or flight” response the body often activates in response to pain. As a result of using these techniques the body often experiences a reduction in skeletal muscle tension, a decrease in vital signs, lowered metabolic rate, and less oxygen consumption.
Cutaneous stimulation can be used to eliminate pain as well. The therapeutic effects of cutaneous stimulation are based on the Gate Control Theory of pain discussed earlier. Cutaneous stimulation focuses on non-painful peripheral skin surfaces, thereby blocking the painful stimulation, causing a decrease in pain. Techniques that use cutaneous stimulation are massage, acupressure, acupuncture, hot and cold applications, and transcutaneous electrical nerve stimulation (TENS).
Massage involves using either the hands or a smooth hard object, such as a sandbag, to hold, clutch, knead and rub the skin and superficial muscle layer. Particular attention is given to areas of pain. In its simplest form, a person may automatically massage a painful area; however, the use of professional massage therapists is growing in popularity.
Both acupressure and acupuncture originated in China. Acupressure entails massaging and/or applying pressure to trigger points. Trigger points are hypersensitive areas in connective or muscle tissue. Acupuncture also uses trigger points but instead of massage, fine sterilized flexible needles are placed at these sites. After the needles are inserted under the skin, the practitioner agitates the needles in order to produce pain relief. Pain relief is based on the belief that health is a state of constantly changing flow of energy which, when unbalanced, causes disease and pain. Acupuncture is thought to help regulate the body’s energy flow back to a state of balance. Though the energy flow theory has not been proven, it has been demonstrated that acupuncture stimulates the body’s endorphins and monoamines.
Heat has been found effective in soothing inflamed muscles and helping to reduce inflammation, particularly for post-traumatic pain, rheumatic aches, and neck and back pain. It is best used after initial inflammation has resolved, usually twenty-four hours after injury occurs. Also, heat can be applied before mobilization is attempted, allowing for a greater degree of movement as well as increased comfort. When heat is applied there is increased blood flow, decreased vasomotor tone, and increased tissue metabolism providing overall effects of analgesia, reduced muscle spasticity, sedation, and elevation of the pain threshold. Heat should not be used, however, at the site of neoplasms, skin desensitization, vascular insufficiency, active infection, or bleeding.
Cold application can be as effective as heat and is usually the first application in an initial acute injury. Cold reduces inflammation and swelling through decreasing vascular flow. It is useful to lessen muscle spasticity and may elevate pain threshold by reducing nerve conduction velocity. Contraindications for cold therapy include vascular insufficiency and conditions directly aggravated by cold, such as Raynaud’s syndrome. Both hot and cold are useful for analgesia, and the choice may be simply a matter of patient preference.
A TENS unit is a portable machine attached to the patient’s skin at specific trigger points or peripheral nerves near the site of pain. The practitioner applies the unit and then, with patient input, adjusts the placement, frequency, and voltage. A TENS unit can either be set for continual or periodically delivered electrical stimulation in order to provide for optimal pain relief. The electrical current stimulates sensory cutaneous nerve endings that are thought to block deeper, more painful sensations. Additionally, TENS may stimulate the release of endorphins. Patients report that the stimulus feels like a pricking or buzzing sensation. TENS has been found to be very effective for certain types of pain such as rheumatic aches, back and neck pain, stump pain, postoperative pain, and neuralgia. People with cardiac arrhythmias or pacemakers should not use a TENS unit. Also, TENS should not be placed over an open wound nor on areas of desensitivity.
Another non-pharmacologic treatment option is biofeedback. Biofeedback requires the use of special equipment and trained practitioners, which can be a costly endeavor. The patient is taught, through systematic trial and error, to condition brain wave activity. The patient is attached to a machine that relays information to him about body changes occurring and thus, he learns to control or replace those associated with pain with a more pleasant experience. Biofeedback has been found to be effective for a variety of painful conditions including headaches and osteoarthritis.
Therapeutic touch is based on an eastern philosophy of energy manipulation. A trained practitioner does not actually touch the patient but rather directs the patient’s energy by moving her hands above the body part experiencing pain. The practitioner must center herself, make an assessment of the patient, unruffle the field, direct and modulate the energy, and also recognize when to stop. Proponents of therapeutic touch believe it to be a healing therapy that can also decrease pain. However, due to spiritual conflicts, some healthcare workers and patients have declined to participate in therapeutic touch.

EASING PAIN WITHOUT SWALLOWING A PILL

Somewhere along the line, pain relief became synonymous with swallowing a “pill”. But nature offers relief that’s just as effective when applied topically, especially for joint and muscle pain. There are two European plants that now have an impressive amount of scientific proof: comfrey and arnica.
There is ‘comfort’ from the herb comfrey for sprains and pains. In fact, according to Jonathon V. Wright, M.D. in his Nutrition and Healing newsletter, the benefits go beyond the regular muscle and joint aches, that it has been used to treat in France and Germany for centuries. Document in a large placebo-controlled clinical trial, 220 patients applied 2 grams of ointment three times a day to the painful knee joint. The ointments were randomly given containing either comfrey or a placebo. In terms of self rated pain, there was a 55% pain decrease in the comfrey group as opposed to only 11% in the placebo group. Similar results were seen in other symptoms of osteoarthritis. Overall, pain was reduced, mobility improved, and quality of life increased. Not bad results for a localized treatment.
An herb that works better than ibuprofen?! It’s Arnica. Arnica is a perennial plant native to Europe and North America. The yellow-orange flowers of this plant are used in medical preparations (both fresh and dried form). Tropically arnica is used for different conditions like bruises, muscle aches, sprains, inflammation, rheumatic pain, wound healing, insect bites and swelling caused mainly due to fractures.

Principles of Pain Treatment

Some principles to remember when administering pain treatments include obtaining the patient’s consent before implementation, particularly for the non-pharmacologic options. Consent can be as simple as a verbal agreement to participate in the activity or the patient may need to sign an actual form. Also teach the patient to inform you of his pain before it becomes severe; pain is best treated before reaching a severe level. Likewise, assessments should occur on a routine basis so that pain does not become severe before it is treated. Be aware that people may not use the word pain but call the experience an ache or discomfort. Also, do not assume that, because the patient received adequate relief for four hours from the last medication administration, he will get the same length of relief from the same amount of medicine at the next administration. Too many variables are changing throughout the day; for instance, a painful procedure may need to be done during one time span or nighttime may occur, when endorphins are known to be lower. It is also important to consider the patient’s willingness and ability to engage in treatment. The best methods will not help if the patient is unwilling or unable to utilize them.

Hope

Certainly another integral part of pain treatment involves documentation. Things that need to be documented include the assessment findings, treatments offered and utilized, and the results of the treatments. Documentation can occur in a variety of forms, from narratives to flow charts or a combination; however, it is most important that it is done routinely in a systematic format. Documentation helps to facilitate regular reassessment and follow-up, and is essential for effective pain management. Examples of documentation forms for assessment and evaluation are included as figures 6 and 7.

Pain Standards Continue a Positive Direction

Practitioners who work with patients with cancer have long been aware of the problems caused by pain. Much of the research on pain has in fact been conducted in an effort to deal with cancer pain. Unfortunately, treatment of cancer pain is still problematic. Identified barriers include lack of knowledge and assessment skills among healthcare professionals, patient and family reluctance to report pain, fears and misconceptions concerning opioid medications, and physicians’ hesitancy to prescribe adequate amounts of opioids due to fear of investigation by regulatory authorities. In order to overcome these barriers and to begin steps toward satisfactory pain management for patients with cancer, many healthcare professionals have focused on the process of institutionalizing pain management. The basic underlying principle of institutionalizing pain management is that healthcare professionals would make pain management a priority within their practice environment. Recognizing the importance of adequate pain management, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) approved standards for pain management.
The Standards discussed below were developed as guidelines for healthcare organizations providing ambulatory care, behavioral health care, home care, hospice, hospital, and long-term care.
The healthcare organization addresses care at the end of life. Patients facing death need respectful, responsive care. Among the responsibilities of caregivers is managing pain aggressively and effectively, and responding to the psychological, social, emotional, spiritual, and cultural concerns of the patient and the family.
Patients have the right to appropriate assessment and management of pain. Pain management is an important part of patient care. Not only should healthcare providers be educated fully on assessment and management, but patients and their families should understand its importance and appreciate their roles in managing pain.
Pain is assessed in all patients. Good patient care requires treatment of all symptoms that might be associated with a disease, condition, or treatment, including pain. The initial assessment of every patient includes pain, and appropriate treatment is provided. More comprehensive assessments may be required by the specific condition of the patient. Measures of pain intensity and quality should be used that facilitate reassessment and follow-up.
Policies and procedures support safe medication prescription or ordering. Procedures supporting safe medication prescription or ordering address, among other issues, appropriate use of patient-controlled analgesia (PCA), spinal/epidural or intravenous administration of medications, and other pain management techniques.
The patient is monitored during the post-procedure period. Pain intensity and quality (e.g., the character, frequency, location, and duration of pain), and responses to treatments are to be monitored continuously.
Rehabilitation is designed to achieve an optimal level of functioning, self-care, self-responsibility, independence, and quality of life. Problems addressed during the rehabilitation process may include pain interfering with optimal level of function or participation in rehabilitation.
Patients are educated about pain and managing pain as part of treatment, as appropriate. Topics to be covered during patient/family education include understanding pain, the potential for pain-accompanying various procedures, the importance of effective pain management, the pain assessment process, and methods for pain management.
The discharge process provides for continuing care based upon the patient’s assessed needs at the time of discharge. Pain and pain management should be addressed as part of the discharge planning process.
The organization collects data to monitor its performance. Each healthcare organization is expected to collect and evaluate data from patients and their families regarding their perceptions of care and service. Data considered for collection include the appropriateness and effectiveness of pain management.

Patient Education

In recent years, the Joint Commission has launched a national campaign entitled “Speak Up”. These initiatives were created to urge patients to take a role in preventing health care errors by becoming active, involved and informed participants on the health care team. The program features brochures, posters and buttons on a variety of patient safety topics. Speak Up™ encourages the public to: ask questions; voice concerns; pay attention and participate in all decisions regarding the care and treatment they receive, and more. In late 2008, Speak Up: “What You Should Know About Pain Management” was introduced. It identifies questions and answers that will help patients find out more about treatments that can be used for pain caused by injury, illness or surgery. Among the topics are: talking about and describing pain, understanding pain treatments, managing pain, and questions to ask caregivers. The brochure encourages patients to ask their caregivers specific questions about pain medication, including doses and times that medication should be taken, side effects, how long the medication will take to work, and what to do if the medication does not work. The brochure is available at http://www.jointcommission.org/PatientSafety/SpeakUp/ www.jointcommission.org/PatientSafety/SpeakUp/.
Despite the wide variety of reasons people seek healthcare, pain is one of the most common presenting symptoms found to accompany health problems. Often, pain is the main reason a person has chosen to enter the healthcare system. And though pain is a common experience, there are a wide variety of types, many influencing factors, and numerous ways to treat it. It has been noted that nurses spend more time with patients in pain than any other member of the healthcare team. Therefore, nurses have a duty to stay informed about pain so they can be competent partners with their patients towards effective pain management.

What is the Future of Pain Research?

In the forefront of pain research are scientists supported by the National Institutes of Health (NIH). Some pain medications dull the patient’s perception of pain. Morphine is one such drug. It works through the body’s natural pain-killing machinery, preventing pain messages from reaching the brain. Scientists are working toward the development of a morphine-like drug that will have the pain-deadening qualities of morphine but without the drug’s negative side effects, such as sedation and the potential for addiction. Patients receiving morphine also face the problem of morphine tolerance, meaning that over time they require higher doses of the drug to achieve the same pain relief. Studies have identified factors that contribute to the development of tolerance; continued progress in this line of research should eventually allow patients to take lower doses of morphine.
One objective of investigators working to develop the future generation of pain medications is to take full advantage of the body’s pain “switching center” by formulating compounds that will prevent pain signals from being amplified or stop them altogether. Blocking or interrupting pain signals, especially when there is no injury or trauma to tissue, is an important goal in the development of pain medications. An increased understanding of the basic mechanisms of pain will have profound implications for the development of future medicines. The following areas of research are bringing us closer to an ideal pain drug.

Systems and Imaging

The idea of mapping cognitive functions to precise areas of the brain dates back to phrenology, the now archaic practice of studying bumps on the head. Positron emission tomography (PET), functional magnetic resonance imaging (MRI), and other imaging technologies offer a vivid picture of what is happening in the brain as it processes pain. Using imaging, investigators can now see that pain activates at least three or four key areas of the brain’s cortex, the layer of tissue that covers the brain. When patients undergo hypnosis so that the unpleasantness of a painful stimulus is not experienced, activity in some, but not all, brain areas is reduced. This emphasizes that the experience of pain involves a strong emotional component as well as the sensory experience, namely the intensity of the stimulus.

Channels

The frontier in the search for new drug targets is represented by channels. Channels are gate-like passages found along the membranes of cells that allow electrically charged chemical particles called ions to pass into the cells. Ion channels are important for transmitting signals through the nerve’s membrane. The possibility now exists for developing new classes of drugs, including pain cocktails that would act at the site of channel activity.

Trophic Factors

A class of “rescuer” or “restorer” drugs may emerge from our growing knowledge of trophic factors, natural chemical substances found in the human body that affect the survival and function of cells. Trophic factors also promote cell death, but little is known about how something beneficial can become harmful. Investigators have observed that an over-accumulation of certain trophic factors in the nerve cells of animals results in heightened pain sensitivity, and that some receptors found on cells respond to trophic factors and interact with each other. These receptors may provide targets for new pain therapies.

Molecular Genetics

Certain genetic mutations can change pain sensitivity and behavioral responses to pain. People born genetically insensate to pain, that is, individuals who cannot feel pain have a mutation in part of a gene that plays a role in cell survival. Using “knockout” animal models, animals genetically engineered to lack a certain gene, scientists are able to visualize how mutations in genes cause animals to become anxious, make noise, rear, freeze, or become hypervigilant. These genetic mutations cause a disruption or alteration in the processing of pain information as it leaves the spinal cord and travels to the brain. Knockout animals can be used to complement efforts aimed at developing new drugs.

Plasticity

Following injury, the nervous system undergoes a tremendous reorganization. This phenomenon is known as plasticity. For example, the spinal cord is “rewired” following trauma as nerve cell axons make new contacts, a phenomenon known as “sprouting.” This in turn disrupts the cells’ supply of trophic factors. Scientists can now identify and study the changes that occur during the processing of pain. For example, using a technique called polymerase chain reaction, abbreviated PCR, scientists can study the genes that are induced by injury and persistent pain. There is evidence that the proteins that are ultimately synthesized by these genes may be targets for new therapies. The dramatic changes that occur with injury and persistent pain underscore that chronic pain should be considered a disease of the nervous system, not just prolonged acute pain or a symptom of an injury. Thus, scientists hope that therapies directed at preventing the long-term changes that occur in the nervous system will prevent the development of chronic pain conditions.

Neurotransmitters

Just as mutations in genes may affect behavior, they may also affect a number of neurotransmitters involved in the control of pain. Using sophisticated imaging technologies, investigators can now visualize what is happening chemically in the spinal cord. From this work, new therapies may emerge, therapies that can help reduce or obliterate severe or chronic pain.

Selected Resources and Websites

Joint Commission on Accreditation of Healthcare Organizations (JCAHO) 630-792-5000
www.jcaho.org

American Pain Foundation
www.painfoundation.org

American Pain Society
www.ampainsoc.org

American Society for Pain Management Nursing (ASPMN)
www.aspms.org/index.htm

Clinical Trials
www.clinicaltrials.gov

National Foundation for the Treatment of Pain
www.paincare.org
www.painandhealth.org

NIH Pain Consortium
www.painconsortium.nih.gov

National Pain Foundation
www.painconnection.org

American Chronic Pain Association
www.theacpa.org

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