Pain management a comprehensive review

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Local anaesthetic agent

Local anesthesia is accomplished through the injection of a drug into the immediate area where surgery will take place. It is widely used and accepted in a variety of clinical settings [68]. Surgery in the office is highly dependent on local anesthesia. While this is convenient it is also associated with pain during administration of anesthesia. This pain can be attributed to factors involving the patient as well as the drug and technique. However, it is important to note that some patients are so adverse to this pain experience that they will either postpone or completely decline the surgery.

Factors involving the patient: The first step any practitioner should take is to carefully explain to the patient exactly what will happen. This will help alleviate anxiety and better prepare the patient psychologically. It is also useful to utilize medications such as diazepam to help relieve anxiety in those patients who are very anxious. Additionally, practitioners can utilize other methods to better help the patient cope with local anesthesia, such as using distraction methods to make the patient more comfortable. Also, rubbing the skin on the injection site reduces that pain of the prick of the needle by stimulating A-fibers and inhibiting C-fibers, a process also known as the gate control mechanism. Another way that pain at the injection site can be reduced is by utilizing a topical anesthetic prior to injection. Yet another way of reducing this pain is by precooling the skin’s surface with ice packs [69].

Factors involving the drugs utilized for local anesthesia: Lignocaine and Sensoricaine are considered to be the most commonly used drugs for local anesthesia. These drugs have an acidic nature, which is what is responsible for the pain response.

Technical factors: Twenty-seven to 30 gauge needles are preferred for the initial injection; this is because finer needles cause less pain [70]. When the initial infiltration is made, expanding tissues cause pain; therefore, if the drug is delivered at a slower rate there will be less pain [71, 72]. Additionally, the volume of the medication delivered at the infiltration site is proportional to the amount of pain experienced; this means that whenever possible a smaller volume of medication should be used.

What is most important about local anesthesia is reassuring and counselling the patient so that they are prepared for the experience. If this is done in a confident, encouraging, and unhurried way it will allow for better results overall.

  1. Opioid analgesics

Opioid analgesics have been used for the treatment of both acute and chronic pain for thousands of years [73]. The ancient Greeks were the first to identify and use opioids – which were originally derived from opium [74, 75]. From these humble roots, opioid analgesics became one of the main medical therapies utilized for pain each year [76]. Although there have been a number of drugs developed to treat different kinds of pain, there is no other single class of medication that has reached the same level of effectiveness for treating moderate to severe pain [77].

Opioids are frequently the first course of treatment for a number of painful conditions. Additionally, they may possess certain advantages over NSAID pain relievers. For instance, opioid analgesics do not have a real “ceiling” dosage; they also do not cause direct organ damage. There are, however, possible side effects that come with opioid analgesics. These include constipation, nausea or vomiting, decrease in sex drive, drowsiness, and depression of the respiratory system. Most patients do develop a tolerance to many of the side effects of opioid analgesics [77].

There is some debate over the use of opioid analgesics. It should be noted that some practitioners express concern over the use of opioids for pain conditions. However, opioids are frequently the only suitable course of treatment to control pain that is severe. This is particularly the case post-operatively [75]. Morphine is most commonly used in the post-operative period; however, some practitioners feel that other treatment action, such as the use of hydromorphone, is more suitable and better tolerated. Even given this, some recent studies indicate that there is no evidence to support the use of hydromorphone as opposed to morphine, and state that there are risks to using both drugs [78].

There is also debate over utilizing opioid analgesics to treat neuropathic pain. This is an area of study that remains a bit controversial. Recently, however, the Cochrane Review discovered that the results of utilizing opioids for neuropathic pain are mixed – shorter term trials produced contradictory results while intermediate trials indicated the efficacy of opioid analgesia for spontaneous neuropathic pain. Across all trials, the side effects that were most commonly seen were constipation, drowsiness, dizziness, and nausea [79].

It is also important to note that some individuals experience adverse reactions to opioid analgesics. This sometimes limits the effective use of opioids in certain patients. One long-term study of patients who took opioid analgesics for an extended period of time indicated that 80% of patients reported suffering at least one adverse consequence; 24% of patients stopped taking the medication as a result of experiencing one of more adverse consequences [80]. Of those who discontinued the medication as a result of an adverse consequence, 41% did so because they experienced constipation, 32% did so because they experienced nausea, 29% did so because they experienced somnolence, and 15% did so because they experienced vomiting [80].

Discontinuation of opioid analgesic treatment may result in pain being treated inadequately. This is not just an inconvenience; there are consequences to inadequate pain control that may be more far reaching. For example, patients who experience significant pain will experience an increase in autonomic and sympathetic activity [81]. In particular, older patients have a chance of developing delirium or other cognitive dysfunction [82]. Using opioid analgesics excessively may also lead to problems. There have been some reports that using opioids excessively can lead into a state of hyperalgesia [74]; this prompts some practitioners to express concern over utilizing opioid analgesics to control pain. However, the lack of effective pain control can on its own lead to a hyperalgesic state that presents as persistent pain [81].

In addition to medical issues that are tied to opioid use, there are some nonmedical issues that sometimes affect the prescribing of these drugs as well as the patient usage of the drugs. Some physicians express concern over prescribing opioids because potential legal issues may arise [83, 84]. Additionally, addiction is a concern, particularly among patients [85]. Clinical opinion polls on the subject indicate that true addiction to opioids occurs in a small percentage of the patient population who receive opioids for chronic pain [86]. Appropriate dosing and use can help ensure that addiction does not become a problem.

  1. NSAIDs

NSAIDs is an abbreviation for nonsteroidal anti-inflammatory drugs. These are a class of drugs that provide relief for pain and fever, and in higher doses have anti-inflammatory effects. The name is meant to distinguish this class of drugs from steroids, which have a similar anti-inflammatory action. NSAID are unusual because they are non-narcotic. The most well-known members of this class of drugs are: aspirin, naproxen and ibuprofen. All of these drugs are available for purchase over the counter in most areas of the world.

NSAIDs are generally indicated to treat acute or chronic pain conditions, particularly those where inflammation is present. Research is currently being done to examine the potential of NSAIDs in treating or preventing other conditions, such as some cancers.

NSAIDs are usually indicated for relieving symptoms for a number of conditions, including [87]:

  • Rheumatoid arthritis and osteoarthritis

  • Inflammatory arthropathies

  • Gout

  • Mestatic bone pain

  • Pain post-procedure

  • Pain due to Parkinson’s disease

  • Fever

  • Renal colic

  • Menstrual pain

  • Headache, including migraine

  • Pain from inflammation and tissue injury

Though commonly thought of as an NSAID, acetaminophen is in fact not in this class of medications. This is because acetaminophen has little anti-inflammatory properties. Acetaminophen works to relieve pain by blocking COX-2, primarily in the central nervous system [88].

NSAIDs are advantageous, but they are also not without risk. The two most prominent adverse reactions seen with NSAIDs are gastrointestinal and renal problems. Side effects, however, are dose dependent. In some cases they are so severe that they present as a risk of ulcer perforation or gastrointestinal bleeding, or death. This limits the usage of NSAIDs.

It is important to remember that NSAIDs are drugs that have the possibility of interacting with other medications. For instance, using NSAIDs and quinolones together can raid the risk of effects in the central nervous system, including seizure [89, 90]. Additionally, people who are on a daily aspirin regimen should be wary of taking other NSAIDs at the same time, as this may affect the cardioprotective aspects of aspirin.

There are still many unexplained aspects of the mechanism of action for NSAIDs. One hypothesis is that there are further COX pathways to explore [88].

  1. Muscle relaxant

Pain management is a high priority for those individuals who suffer from pain. The usage of muscle relaxants to manage pain is gaining ground. These drugs include medications that reduce muscle spasms, such as diazepam, lorazepam, metaxalone, or alprazolamor some combination of drugs, such as orphenadrine and paracetamol [91]. Additionally, these drugs include medications that prevent increased muscle tone, such as baclofen and dantrolene. Antispasmodic and antispasticity medications have gained clinical acceptance as well. However, research for antispasmodic and antispasticity medications indicate that there are doubts as to the effectiveness of these medications.

In one review [91] conducted to determine the safety and efficacy of muscle relaxants for managing pain in patients with rheumatoid arthritis, researchers discovered that across six trials – and with a total of 126 participants – there was no indication of any beneficial effects of muscle relaxants over a placebo for treatment of pain, and that in trials that lasted longer than 24 hours, participants experienced a marked increase in the likelihood for adverse effects. These effects were primarily side effects in the central nervous system, including such effects as dizziness and drowsiness.

  1. Anti seizure drug

Anti-seizure drugs were originally designed and intended for use in epileptics. However, these drugs work to calm the nerves, which in turn can aid in quieting stabbing, burning, or shooting pain, primarily that found in nerve damage.

Many things can damage the nerves, including injury, disease, surgery, or exposure to toxins [92]. After damage, these nerves are activated in an inappropriate way and relay pain signals that do not serve any useful purpose. Pain from nerve damage is frequently one of the most difficult to control and can be debilitating.

Nerve damage, also called neuropathy, may be caused by a number of conditions, which includes:

  • Diabetes. It is not uncommon to experience nerve damage as a result of high blood sugar levels, which are common in diabetes. Usually the first symptom of neuropathy in diabetics is numbness or pain in the hands and feet.

  • Shingles. Shingles is caused by the same virus that causes chicken pox and presents as a rash that includes blisters that are extremely painful and itchy. Postherpetic neuralgia is the condition that occurs if the pain from shingles continues after the rash has disappeared. The risk of shingles increases an individuals age, so it is a good precautionary measure for anyone over 60 to make sure they receive the zoster vaccine, which can assist in preventing this condition.

  • Chemotherapy. Sometimes chemotherapy drugs may damage nerves, which in turn causes pain and numbness that is usually first experienced as a tingling in the fingers and toes.

  • Herniated disk. Damage to the nerves may occur as a consequence of a herniated disk when the disk squeezes a nerve passing through the vertebrae too tightly.

  • Inherited neuropathies. Some types of neuropathy is passed on genetically. These neuropathies may affect different nerves; this is all dependent on the type of disorder. The most common of these neuropathies is Chacot-Marie-Tooth disease, which works by affecting the individual’s motor nerves and sensory nerves.

It is not fully understood how anti-seizure medications help with pain management, but these medications seem to interfere with the overactive relay of pain signals that are sent from damaged nerves.

Anti-seizure medications, while helpful, do have their disadvantages. One such disadvantage – which is one of the warnings the Food and Drug Administration [93] has indicated as a danger of anti-seizure medications – is that all of these medications are linked to an increase in suicidal thoughts or behaviour. Patients and practitioners must maintain effective communication through the prescribing period to ensure that these types of thoughts and behaviour are promptly caught and managed.

  1. Tricyclic antidepressants.

Antidepressants are usually seen as a mainstay for treating pain conditions, in particular those that are chronic. This is often the case even when depression is not a factor. While these are not approved by the FDA to treat chronic pain conditions, they are widely utilized.

Antidepressants are utilized to treat a number of pain conditions, including those caused by:

  • Arthritis

  • Postherpetic neuralgia

  • Migraine

  • Tension headache

  • Fibromyalgia

  • Pelvic pain

  • Diabetic neuropathy

  • Low back pain

How these drugs work is not entirely understood. One theory is that antidepressants may increase the neurotransmitters in the spinal cord that in turn reduce pain signals. However, it is important to note that antidepressants do not provide immediate pain relief. Pain relief with antidepressants may occur in the first week following starting an antidepressant regimen, but maximum pain relief can take several weeks. Pain relief that comes from an antidepressant regimen is usually moderate.

One of the most effective groupings of antidepressant drugs for pain are tricyclic antidepressants [94]. These include:

  • Amitrityline

  • Clomipramine

  • Desipramine

  • Imipramine

  • Nortriptyline

While useful, tricyclic antidepressants are not without their disadvantages. These disadvantages mostly come in the form of uncomfortable side effects, including blurred vision, dry mouth, weight gain, changes in blood pressure, drowsiness, constipation, and difficulty urinating. To help prevent side effects, practitioners should start patients at a lower dose and slowly work to increase the dose. The doses that are usually used for pain management are usually lower than the doses utilized to treat depression.

  1. Alpha adrenergic agonist.

Alpha adrenergic agonists are commonly utilized for ailments such as bradycardia [95]. However, they have their uses for pain management as well. Alpha adrenergic agonists are a kind of sympathomimetic agent that works by simulating alpha adrenergic receptors. There are two classes associated with the alpha adrenergic receptor: α1 and α2.

Two drugs in particular have been shown to provide very effective pain relief. Both are alpha-2 adrenergic agonists [96]. The first is tizanidine, which works very effectively at managing pain that results from tension headache as well as back, neuropathic, and myofacial pain. The second is clonidine, which works well at treating neuropathic pain that hasn’t responded well to other treatments.

  1. Treatment of migraine headache. Migraine treatment is unique in that pain can often be anticipated with migraines, which means that the goal of treatment is focused on both prevention and relieving symptoms [27]. There are several pharmacological treatments that specifically treat migraines, although some treatments that work on other types of pain – such as the application of ice to the forehead – are also useful in treating migraine headache.

Drug use for migraines is divided into two categories – acute, which involves medication that is taken at occurrence in an attempt to ease or abort migraine symptoms; and preventative, which means the individual takes a medication every day to prevent occurrence of migraine headache.

Acute treatments include:

  • Triptan drugs to help increase the levels of serotonin in the brain. This causes blood vessels to constrict, which lowers the pain threshold. These drugs are the preferred treatment method for migraine, and they ease moderate to severe pain. Triptans are available as injections, tablets, or nasal sprays.

  • Ergot derivative drugs work by binding to serotonin receptors, which in turn decreases the transmission of messages of pain along the nerve fibers. These drugs are more effective if the individual is still in the early stages of a migraine. Ergot derivative drugs are available as nasal sprays or injections.

  • Nonprescription analgesics are also good choices for treating migraine. These include ibuprofen, acetaminophen, or aspirin. Some brands – such as Excedrin – are specifically formulated to treat less severe migraines. These brands are usually considered combination analgesics, as they frequently combine a non-prescription analgesic with another pain relieving agent, such as caffeine.

  • Non-steroidal anti-inflammatory medication can help by reducing inflammation and alleviating pain.

  • Taking a combination that includes a nausea relief drug can help by easing queasiness that is frequently seen with migraine headache.

  • Sometimes narcotics are the way to go in treating migraine. Narcotics should be used for severe pain. They should also only be used for brief periods – if the individual experiences chronic headaches narcotics are not a good option.

Prevention treatment should be seriously considered if the individual experiences migraine one or more times per week, or if their migraines are disabling.

Preventative treatments include:

  • Anticonvulsants, which are often helpful for people who experience other kinds of headache in addition to experiencing migraine. Anticonvulsants were originally developed to treat epilepsy; however, they are also useful for dampening pain impulses.

  • Beta blockers are frequently effective in treating migraine.

  • Calcium channel blockers work to stabilize the walls of blood vessels and work by preventing the blood vessels from widening or constricting. This helps alleviate the occurrence of headache.

  • Additionally, there are several natural treatments available to help prevent migraine. These include vitamin B2, coenzyme Q10, magnesium, and butterbur.

  1. Non Pharmacological management

The non-pharmacological management of pain refers to pain management without medication. Generally, non-pharmacological pain management uses ways to alter thoughts or focus to help decrease pain [55].

  1. Cutaneous stimulation and massage

Massage therapy has ancient origins and can be highly varied [97]. Massage therapy helps alleviate pain by releasing neurochemicals, including oxytocin, a neuropeptide. Massage has been linked to reduced blood pressure and heart rate and can also lower muscle or myofascial tension. The benefits of massage can become ongoing and give long term pain relief when the massage therapy is regular and consistent.

Massage is particularly good for treating back pain or for treating certain types of headache, such as migraine. In one study of individuals with low back pain, those who received regular massage therapy had less intense pain as well as a decrease in the quality of pain. At a one-month follow-up, 63% of patients who received massage therapy reported having no pain [98]. Likewise, in a study of 26 migraine sufferers, those who received regular massage therapy sessions (defined as two 30-minute massages per week for 5 weeks) experienced less pain and sleep disturbances as well as more days free of headache [99].

  1. Ice and heat therapies

Ice and heat therapy is simple, yet effective, at managing certain types of pain, particularly pain in the lower back, muscle strains, or pain from arthritis [100]. It is essential, however, to understand how to properly use these therapies to maximize pain relief.

Utilizing ice packs for the relief of back pain [101]:

An ice or cold pack should be applied to the affected area for not more than 20 minutes at one time; application can take place several times per day.

There are different types of ice or cold packs that may be used to help relieve pain in the lower back. Patients may select whichever option works best, or whichever option they prefer. These options include:

      • Reusable cold packs or ice packs. There are a number of different kinds of reusable packs available for purchase at drug stores. These packs are often filled with gel and can be refrozen after each use. Individuals may also opt to make their own reusable gel ice packs. This is done by filling a small sealable bag with liquid dishwasher detergent and freezing it. Other homemade, reusable options include: placing ice in a plastic bag and holding on the affected area; freezing a damp towel and then placing it on the affected area; freezing a wet sponge, and once it is frozen placing it in a bag that is then wrapped in a towel or sock before applying to the affected area; filling a sock with rice and freezing it before placing it on the affected area; utilizing a frozen bag of peas for a quick ice pack.

      • Disposable/Instant ice packs. Some packs are for single use only. These are generally available at most drug stores. However, a distinct advantage that many single use packs have is that they have the ability to become cold almost immediately. They also generally stay colder for a longer amount of time, even when used in warmer temperatures. There are disadvantages to single use packs, one being that they can only be utilized once, which can make them more expensive than reusable or homemade ice packs.

Ice massage therapy may also be used for pain in the back. This can be done by using regular ice cubes, or by freezing water in a paper cup and then peeling part of the cup away to reveal the block of ice. Ice massages may be done by the patient themselves or by someone else. Patients can give themselves ice massages by lying to the side and reaching around the back to apply ice to the affected area. There are five steps to a successful ice therapy massage:

      • The ice should be applied gently and massaged on the skin in a circular motion.

      • The focus of the massage should be kept to an area of six inches around where the pain is felt.

      • It is important not to apply the ice directly to the bony portion of the spinal column.

      • Ice therapy massage should be done in 5 minute increments to avoid ice burn.

      • Massage may be repeated 2 to 5 times per day.

Patients should usually not apply the ice directly to skin without barrier in order to avoid burning the skin. In ice massage therapy, however, it is okay to apply ice directly to skin because the ice does not stay stationary. The aim of ice massage therapy is to make the area numb without burning the skin. After the numbness occurs, the individual can perform gentle movement that applies minimal stress to the affected area. Once the numbness wears off, ice massage therapy can be conducted once more for another cycle. Ice massage is most helpful in the 48 hours first following an injury. After this time period, heat therapy is generally more beneficial to healing.

There are some precautions individuals should take to avoid getting ice burns. These include:

      • Being certain to keep ice moving in a slow and circular motion without staying in one place for too long.

      • Limiting ice massage to five minute massage periods.

      • Making certain not to fall asleep with ice resting directly on skin.

      • Avoiding ice application of all kinds if the individual has certain health conditions, such as those who have rheumatoid arthritis, cold allergic conditions, areas of impaired sensation or paralysis, or Raynaud’s Syndrome.

Beyond being comforting, heat serves as an effective therapy for pain relief. Heat therapy has the ability to provide pain relief as well as healing benefits, particularly for those with lower back pain [102]. Heat therapy works to prevent pain, particularly in the lower back, through a number of mechanisms, including:

      • Dilation of the blood vessels in the muscles surrounding the spine. This increases oxygen flow as well as the flow of nutrients to the muscles, which helps to heal damaged tissue.

      • Stimulation of the skin’s sensory receptors; this means that applying heat therapy serves to decrease the transmission of pain signals to the brain and relieve discomfort.

      • Facilitate the stretching of soft tissues around the spine. This means that there will be a decrease not only in injury but also in stiffness. This serves to increase flexibility as well as provide a more universal feeling of comfort.

Heat therapy has the advantage of being inexpensive and easy as well as very beneficial. Heat therapy is much less expensive in general than many other forms of therapy – it is often even free, such as when the individual takes a hot bath. It is also easy – heat therapy can take place at home or even by utilizing on the go portable heat wraps. Finally, heat therapy is appealing in that it is non-invasive and non-pharmaceutical.

Lower back pain from injury is not the only kind of pain that heat therapy can alleviate. Heat therapy also has the ability to reduce pain or soreness post-exercising [103]. One recent [104] study of more than 60 participants that tested the effects of low level heat therapy to delay the onset of muscle soreness concluded that it is possible to prevent delayed-onset muscle soreness by wearing heat wraps on the lumbar region prior to exercise [105]. This is a particularly important find because it is imperative to back health to remain active, as the back and spine benefits from activities that increase blood flow. Exercise also helps maintain flexibility, which is important to back health as well. However, muscle pain that results from exercising proves to be a deterrent to maintaining regular exercise activity. Therefore, research indicates that since heat wrap therapy can help minimize or eliminate the muscular discomfort that results from exercise, more individuals who are concerned about pain now have hope of staying on track with an exercise program if they apply heat therapy before exercising [106].

Low-level heat therapy wraps are available over the counter at most drug stores, or at medical supply outlets.

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