MANAGEMENT OF PAINS IN SURGICAL PRACTICE�

Prof. dr. med. Oseni-Momodu

CMAHS

JOS, CAMPUS

Monday 23/04/18

HISTORY OF PAIN MANAGEMENT IN SURGERY

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• Long ago before the 19^th Century, surgical procedure was necessarily a very painful experience.
• Patients were held by strongmen or tied unto immovable objects to be able to perform a surgery.
• Alcohol was often used to stupefy the patient

• The surgeon in the circumstance had to work quickly and bravely by force having also helped himself with some of the alcohol to steel his nerves.

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• Operations were few because of the agony and high mortality from sepsis and shock; tooth extraction and amputation for tuberculosis, osteomyeIitis, and trauma were the major operations.

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• Other common operations were lithotomy for bladder stone, drainage of abscess, excision of glands, and urethral dilatation.

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• Emergencies consisted of strangulated hernia, treatment of wounds and reduction of fractures and dislocations.

PAIN HISTORY TAKING

Description: severity, quality, location, temporal features, frequency, aggravating & alleviating factors

Previous history/Past medical history

Context: social, cultural, emotional, spiritual factors (cf flogging during marriage ceremonies & the non expression of pain)

Interventions: Pain therapy? Surgery

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ACUTE PAIN MANAGEMENT

• Pain is one of the most common symptoms experienced by (surgical) patients. It has however been poorly and historically evaluated and frequently undertreated.

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• The doctors cannot feel pain like the patient does; he therefore tends to give less than optimal medical doses.

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• Medical personnel must continue to increase their knowledge of pain and its control and attempt to provide optimal analgesia as a key component of patient care.

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• Surveys demonstrate that continued improvement is necessary to further reduce the high incidence of moderate to severe acute postoperative pain.

• Acute pain occurs frequently in the setting of surgery and trauma.

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• The pain experience may be part of the symptom complex that prompts the patient to seek medical care, or it may be caused by tissue injury sustained as a result of surgery or trauma and so serves a useful function.

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• The term acute refers to pain that is expected to be of relatively short duration and that should resolve with tissue healing or withdrawal of the noxious stimulus.

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• Acute pain generally resolves within minutes, hours, or days.

Mechanisms of Acute Pain

• The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.”

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• This definition emphasizes not only the sensory experience but also the affective component of pain.

Characteristics of Nociceptive Pain

• Chronic pain, which can persist for years, is defined as pain that persists for at least 1 month.

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• Chronic pain serves no useful function

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• It is now recognized not only as a part of certain disease processes such as cancer but also often as a disease itself.

CHRONIC PAIN

B. NEUROPATHIC Characteristics of Neuropathic Pain

2. NEUROPATHIC ……..

FEATURES OF NEUROPATHIC PAIN

CENTRAL PAIN SYNDROME

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• Is a neurological condition caused by damage to or dysfunction of the central nervous system (CNS), which includes the brain, brainstem, and spinal cord.
• This syndrome can be caused by stroke, multiple sclerosis, tumors, epilepsy, brain or spinal cord trauma, or Parkinson's disease.
• The character of the pain associated with this syndrome differs widely among individuals partly because of the variety of potential causes.
• Central pain syndrome may affect a large portion of the body or may be more restricted to specific areas, such as hands or feet.
• The extent of pain is usually related to the cause of the CNS injury or damage.
• Pain is typically constant, may be moderate to severe in intensity, and is often made worse by touch, movement, emotions, and temperature changes, usually cold temperatures.

Prognosis

CENTRAL PAIN SYNDROME …….

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• Individuals experience one or more types of pain sensations, the most prominent being burning. Mingled with the burning may be sensations of "pins and needles;" pressing, lacerating, or aching pain; and brief, intolerable bursts of sharp pain similar to the pain caused by a dental probe on an exposed nerve.

• Individuals may have numbness in the areas affected by the pain.

• The burning and loss of touch sensations are usually most severe on the distant parts of the body, such as the feet or hands.

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• Central pain syndrome often begins shortly after the causative injury or damage, but may be delayed by months or even years, especially if it is related to post-stroke pain.

TREATMENT

TREATMENT

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• Pain medications often provide some reduction of pain, but not complete relief of pain, for those affected by central pain syndrome.

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• Tricyclic antidepressants such as nortriptyline or anticonvulsants such as neurontin (gabapentin) can be useful.

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• Lowering stress levels appears to reduce pain.

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Central pain syndrome is not a fatal disorder, but the syndrome causes disabling chronic pain and suffering among the majority of individuals who have it.

Schematic diagram outlining the nociceptive pathway for transmission of painful stimuli.  (From Ferrante FM, VadeBoncouer TR: Postoperative Pain Management. New York, Churchill Livingstone, 1993.)

TYPES OF PAIN

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A. NOCICEPTIVE

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Which are either somatic or visceraal pains

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Visceral pains are of �heart, liver, �pancreas, gut, �etc.

Somatic pains are of the –

bones, joints connective tissues muscles

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NOCICEPTION

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• The tissue injury that leads to the complaint of pain results in a process called nociception, the sensory nervous sytem’s process of encoding noxious stimuli.
• which has four steps: transduction, transmission, modulation, and perception ( Fig.)

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• With TRANSDUCTION, the noxious stimulus is converted into an electrical signal at free nerve endings, which are also known as nociceptors which are widely distributed throughout the body in both somatic and visceral tissues

• With TRANSMISSION, the electrical signal is sent via nerve pathways toward the CNS. Nerve pathways include primary sensory afferents (primarily Ad and C fibers) that project to the spinal cord, ascending tracts (including the spinothalamic tract) to the brainstem and thalamus, and thalamocortical pathways to the cortex.

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• MODULATION, the process that either enhances or suppresses the pain signal, occurs primarily in the dorsal horn of the spinal cord, in particular, the substantia gelatinosa.

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• PERCEPTION, the final step in the nociceptive process, occurs when the pain signal reaches the cerebral cortex.

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• The first three steps in nociception are important for the sensory and discriminative aspects of pain.

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• The fourth step, perception, is integral to the subjective and emotional experience.

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METHODS OF ANALGESIA

• There are multiple agents, routes of administration, and modalities available for effective management of acute pain.
• Analgesic agents include opioids, non steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and local anesthetics.
• Less traditional agents that may be used more frequently in the future include clonidine, dexmedetomidine, dextromethorphan, and gabapentin.
• Routes of administration include the oral, parenteral, epidural, and intrathecal routes. The oral route is the preferred route for analgesic delivery.

• Patients experiencing mild to moderate acute pain and who can receive agents orally can obtain effective analgesia.

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• Parenteral administration is preferred for patients experiencing moderate to severe pain, patients who require rapid control of pain, and those who cannot receive agents through the gastrointestinal tract.

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• The IV route is preferred over intramuscular and subcutaneous injections when the parenteral route is indicated.

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• Intramuscular injections are painful, result in erratic absorption, and lead to variable blood levels of the administered agent

OPIOIDS

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• Opioids are potent analgesic agents that are effective but frequently underused.
• Receptors in the CNS and probably also in peripheral tissues, modulate the nociceptive process by binding to opioids.
• The best-characterized opioid receptors are μ1, μ2, δ, κ, ε, and σ receptors.
• The μ1 receptors are involved in supraspinal analgesia.
• The δ and κ receptors are involved in spinal analgesia.
• Opioids can be administered by multiple routes, including oral, parenteral, neuraxial, rectal, and transdermal.

• Opioids have varying degrees of potency. STRONG OPIOIDS are ideal for moderate to severe pain and for pain that is constant in frequency.

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• Morphine, the prototype strong opioid, can be delivered by a variety of routes and techniques. Other strong opioids include hydromorphone, fentanyl, and meperidine.

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• Morphine is metabolized to morphine-3-glucoronide and morphine-6-glucoronide, which can accumulate in patients who have renal impairment.

OPIOIDS

• For MODERATE TO SEVERE PAIN in patients with renal dysfunction, fentanyl and hydromorphone are more suitable agents. Meperidine should be withdrawn for it causes seizures.
• Fentanyl is available in a transdermal preparation, but this route is not recommended for acute pain management.
• WEAK OPIOID AGENTS are suitable for mild to moderate pain that is intermittent in frequency.

OPIOIDS ….continued

• One major barrier to the effective use of opioid agents by patients, physicians, and other health care providers is the fear of addiction, which can be manifested as
• underdosing,
• use of excessively wide dosing intervals,
• administration of weak opioids for moderate to severe pain, and
• underreporting of pain.

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In the setting of acute postoperative pain, the use of opioids has not been shown to be a risk factor for the development of an addiction disorder.

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• Key terms to understand include tolerance, addiction (psychological dependence), and physical dependence.

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• The duration of opioid treatment is a factor in the development of physical dependence.
• The short-term use of opioids in the perioperative period rarely results in physical dependence.
• Slow tapering of opioids generally prevents withdrawal symptoms

NONSTEROIDAL ANTI-INFLAMMATORY AGENTS -NSAIDs

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• NSAIDs are an important component of perioperative analgesia that, when used as a part of the analgesic regimen, reduce pain and can decrease opioid consumption.

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• Their mechanism of action is achieved through inhibition of cyclooxygenase (COX) enzyme activity, which results in decreased production of prostaglandins.

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• Prostaglandins are potent mediators of pain that act directly at nociceptors and also increase nociceptor sensitivity. Inhibition of prostaglandin production results in analgesia but can also lead to side effects such as gastric ulceration, bleeding, and renal injury.

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• These side effects have limited the used of NSAIDs in the perioperative period. Contrary to previous evidence that NSAIDs act mainly in peripheral tissues, there is now evidence that NSAIDs also work in the CNS.

CAUTION WITH NSAIDs

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• NSAIDs should be avoided in patients with a history of gastropathy, platelet dysfunction, or thrombocytopenia; in those with a history of allergy to the agent; and in patients with renal impairment or hypovolemia.

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• It is used with caution in elderly patients

• There are indications that COX-2 inhibitors are associated with a lower incidence of gastropathy.

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• Concerns about the use of these selective NSAIDs include the risk for cardiovascular events and their effects on bone healing.

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• The newer agents (celecoxib, rofecoxib, valdecoxib) are selective COX-2 inhibitors. COX-2 inhibitors appear to offer similar analgesia with a somewhat reduced risk of causing gastrointestinal bleeding, bleeding diathesis, and renal compromise. They have mostly been studied and used clinically in the management of arthritis-related pain but are becoming more frequently used in the perioperative period

LOCAL ANESTHETICS FOR THE MANAGEMENT OF ACUTE PAIN

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• Local anesthetics work by blocking CONDUCTION in nerve fibers, the second step in the process of nociception for regional anesthesia, but their effects last into the postoperative period and contribute to preemptive analgesia.

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• Local anesthetics used in doses lower than that required for anesthesia can also provide analgesia by a variety of application techniques, including local infiltration, topical application, epidural infusion, and peripheral nerve infusion.

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• Local infiltration of local anesthetic before the surgical incision may reduce the sensitization of nociceptors and thereby result in reduced CONDUCTION of pain signals to the CNS.

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• This may be manifested as decreased postoperative pain and analgesic requirements.

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• Local infiltration on wound closure may also be helpful.

• TOPICAL APPLICATION OF LOCAL ANESTHETIC includes the use of agents such as eutectic mixture of local anesthetics (EMLA cream), which contains prilocaine and lidocaine. This agent can be used for superficial procedures and can be placed before the surgical incision.

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• Placement of peripheral nerve catheters for local anesthetic infusion is becoming a frequently used technique for postoperative pain management. cf fracture plane anaesthesia

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• The development of disposable and lightweight infusion pumps is leading to the increasing use of peripheral nerve infusion in the ambulatory setting and has been shown to provide improved postoperative pain control when compared with opioid administration.

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Combination Analgesic Therapy

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• By combining agents from different analgesic classes, synergy may be obtained.
• Gabapentin, an anticonvulsant used for the management of chronic neuropathic pain, has shown efficacy for analgesia in the acute postoperative period, including improved pain control and reduced opioid-related side effects.
• The concept of preemptive analgesia is to influence the analgesic process before initiation of the noxious stimulus (e.g., surgical incision, im. injections).

• The concept of preemptive analgesia minimizes sensitization of the nervous system and moderates the process of NOCICEPTION described previously.

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• It is an effective (preemptive) analgesia technic resulting in decreased postoperative pain, reduces postoperative analgesic requirement, decreased side effects from analgesics, increased compliance with postoperative rehabilitation, and decreased incidence of chronic postsurgical pain syndromes

NEURAXIAL ANALGESIA

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• Neuraxial routes of administration include the EPIDURAL AND INTRATHECAL (subarachnoid) routes.

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• These modes of administration require consultation from acute pain specialists, usually anesthesiologists who receive specialized training in use of the neuraxial route for the administration of anesthesia and analgesia.

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• Neuraxial agents are delivered by a single injection into the epidural or subarachnoid space, by intermittent injections through an indwelling epidural catheter, by continuous infusion through an indwelling epidural catheter, or by patient-controlled epidural analgesia through an indwelling catheter OR PUMP. (deliveries, orthopaedic/trauma joint replacement surgeries)

Intravenous Patient-Controlled Analgesia (IV PCA)

( SHOW SIS. WURA)

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• An increasingly popular and effective modality using the parenteral route of administration is IV PCA.

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• This modality minimizes the steps involved in the delivery of analgesia and increases patient autonomy and control. Opioids are the agent of choice for IV PCA.

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• In comparing IV PCA with conventional intermittent nurse-administered opioid delivery, patients obtain prompt analgesia, receive smaller doses of opioids at more frequent intervals, can maintain blood concentration of drug in the analgesic range, and have a lower incidence of drug-related side effects.

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• Candidates for IV PCA are patients who can understand the basic steps involved in use of the device, who are willing to assume control of their analgesia, and who are physically capable of activating the device.

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• Such patients include children as young as 4 years of age and most adults, including geriatric patients

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• The use of structured protocols and guidelines is encouraged for facilities using IV PCA. The medical and nursing staff need to receive training in the care of patients using this modality

CHRONIC PAIN (CHRONIC PAIN SYNDROME)

CENTRAL PAIN SYNDROM

• In a subset of patients, pain persists after the expected healing time despite the lack of sufficient pathology to account for the pain.
• Pain that persists for 1 month & beyond the expected time for recovery or initial onset is considered evidence of a chronic pain syndrome.
• Such patients with persistent pain frequently use words such as burning, shooting, and shock-like to describe their pain, which is generally associated with a neuropathic pain syndrome.
• (Slides 12-14)

CHRONIC PAIN

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• Neuropathic pain syndromes occur when there has been injury to the nervous system (central, peripheral, or both).
• Central sensitization is believed to underlie the development of neuropathic pain. Examples include patients with persistent pain after head and neck surgery, thoracotomy, mastectomy, hernia repair, and amputation.
• Certain factors that may increase the risk for chronic pain include infection at the surgical site, intraoperative trauma to nerves, diabetes mellitus, and nerve entrapment by cancer.
• There is some evidence that PREEMPTIVE ANALGESIA may help minimize the occurrence of these syndromes.

• Because chronic pain syndromes can be difficult to diagnose in the early postoperative period, it is important for physicians to perform appropriate PAIN ASSESSMENT during postoperative follow-up.

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• For instance, after amputation, patients might consider it strange to continue to feel sensation and pain in the location of an amputated limb and might be reluctant to volunteer information that they believe could suggest psychological instability; Phantom pain

PAIN ASSESSMENT AND EVALUATION

Patient Risk Stratification

• An assessment of chronic pain should include a detailed assessment of the pain itself, including:
• Intensity, quality, location, and radiation of pain
• Identification of factors that increase and decrease the pain; and
• Review of the effectiveness of various interventions that have been tried to relieve the pain.

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The impact of pain on quality of life (eg, function in work, relationships, and recreational activities; effects on sleep, mood, level of stress) should also be assessed because improvement in these domains may be a goal of pain treatment and a measure of the efficacy of interventions.

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• In such circumstances, appropriate questioning may elicit the complaint and result in patient reassurance and appropriate treatment.

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• Referral to a pain medicine consultant is appropriate when the diagnosis of a chronic postoperative pain syndrome is made.

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• Treatment modalities include the use of adjuvant medications such as antidepressants and anticonvulsants, nerve blocks, physical therapy, and psychological techniques

Patients With a History of Substance Abuse

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• Patients with a history of substance abuse are frequently UNDERTREATED for acute pain complaints.

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• The stigma associated with drug abuse, misunderstanding on the part of health care providers, and inappropriate pain behavior contribute to under treatment in this patient population.

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• Effective analgesia can be obtained with strict guidelines, patient education, and appropriate use of consultants and modalities such as regional analgesia

PEDIATRIC PATIENTS

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• Pediatric patients experience similar severity of acute postoperative and post-traumatic pain as adults. A major historical myth that has been refuted is the belief that neonates, infants, and children do not perceive pain as adults do.

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• Effective analgesia for a pediatric patient experiencing acute pain can be achieved with PAIN ASSESSMENT tools that are tailored for this population and the use of modalities and agents similar to those used for adults.

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• Dosage selection in a pediatric patient must be guided by calculations based on patient weight

ELDERLY PATIENTS

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• As the proportion of elderly in the general population increases, a growing percentage of geriatric patients are undergoing surgery or being treated for trauma.

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• These patients will require PAIN ASSESSMENT AND EVALUATION tailored to their mental status and cognitive abilities.

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• The modalities and agents used to manage acute pain in this population must take into consideration underlying disease states and decreased organ function.

PAIN CONTROL IN MALIGNANT DISEASE

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• Pain is a common symptom associated with cancer, more so during the advanced stages.
• In intractable pain, the underlying principle of treatment is to encourage independence of the patient and an active life in spite of the symptom.
• The World Health Organization’s booklet advises use of a ‘pain step ladder’:
• First step. Simple analgesics: aspirin, paracetamol, nonsteroidal anti-inflammatory agents, tricyclic drugs or anticonvulsant drugs.
• Second step. Intermediate strength opioids: codeine, tramadol or dextropropoxyphene.
• Third step. Strong opioids: morphine (pethidine has now been withdrawn).

• Oral opiate analgesia is necessary when the less powerful analgesic agents no longer control pain on movement, or enable the patient to sleep.

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• Fear that the patient may develop an addiction to opiates is usually not justified in malignant disease.

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• It is also important to distinguish between the addiction and dependence; the former being a psychosocial phenomenon while the latter is a pure physiological response to a given drug.

• Oral morphine, often used for chronic pain, can be prescribed in short-acting liquid or tablet form and should be administered regularly every 4 hours until an adequate dose of drug has been titrated to control the pain over 24 hours.

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• Once this is established, the daily dose can be divided into two separate administrations of enteric-coated, slow-release morphine tablets (MST morphine) every 12 hours.

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• Infusion of subcutaneous, intravenous, intrathecal or epidural opiate drugs is also practiced, cf morphine pump
• In all this caveat emptor constipation

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SUMMARY BOX

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Options for controlling severe pain in malignant disease

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■ Oral morphine using slow-release, enteric-coated tablets

■ Slow infusion of opiates subcutaneously, by epidural, or intrathecal route

■ Neurolysis for patients with limited life expectancy

■ Palliative hormone, radiotherapy, or steroids control pain from swelling

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REFERENCES

Principles of Surgery, Schwartz,

Sabistone, Text book of Surgery, 18^th Edition

Bailey and Love, Short Practice of Surgery

Baja/Badoe: Principles and Practice of Surgery, 26^th Edition

Including Pathology in the Tropics, 3^rd Edition

Slides 10,11, 12 -16 courtesy

Dr. AGBO,

Department of Anaesthesia , JUTH

modified.

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Na gode kware kware

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DANKE SCHOEN