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430 PHCLJamilah Alsaidan, Msc
Pain Management
Pain ManagementHumans have always known and sought
relief from pain.Today, pain's impact on society still is
great, and indeed pain complaints remain a primary reason patients seek medical advice.
Regrettably, many healthcare providers do not receive adequate training in this area, and new information is not widely disseminated and/or understood. Clearly, pain management is enhanced when a multidisciplinary approach is applied.
Pain ManagementDefinition:The accepted current definition of pain is:
"an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.“
Pain often is so subjective, however, that many clinicians define pain as whatever the patient says it is.
The best care is achieved when the patient comes first.
Pain ManagementEpidemiologyData from the National Health and Nutrition
Examination Survey indicate that 1 in 4 Americans have suffered pain that lasts for more than 24 hours in the previous month and in those reporting pain, 42% state that it lasted more 1 year.
The annual cost of pain to U.S. society can be estimated to be in the billions of dollars.
Chartbook on trends in health to Americans with special feature on pain. 2006; 68-91. www.cdc.gov/nchs/data/hus/hus06.pdf.
Pain ManagementIn 1 year, an estimated 25 million
Americans will experience acute pain due to injury or surgery, and one-third of Americans will experience severe chronic pain at some point in their lives.
These numbers are expected to rise, as average life expectancy is likely to increase
Despite ongoing efforts, pain often remains underestimated and undertreated.
Pain ManagementPain is categorized according to its cause,
location, duration, and clinical features
Pain
Acute
Useful purpose of alerting the individual
To an injury and initiating a reflex withdrawal from an
offensive stimulus
Chronic
Is persistent
Serves no biologic protective purpose Can cause undue stress and
suffering
Pain ManagementPain Sensation involves a series of complex
interactions between peripheral nerves and the central nervous system
This process is modulated by excitatory and inhibitory neurotransmitters released in response to stimuli
Such stimuli can be physical, psychological, or both
E.g. Physical stimulus- burn or cut to skinIn a short time, local reactions occur in the
damaged area that initiate the release of chemical mediators involved in inflammation
This is followed by sensitization of nerve endings, which ultimately send signals to the sensory cortex of the brain
Pain Management
Pain Management
It is either: somatic (arising from skin, bone, joint,
muscle, or connective tissue) visceral (arising from internal organs such
as the large intestine or pancreas). Stimulation of free nerve endings known as
nociceptors is the first step leading to the sensation of pain.
These receptors are found in both somatic and visceral structures and are activated by mechanical, thermal, and chemical factors.
Pain Management- Nociceptive pain:
Release of bradykinins, K+, prostaglandins, histamine, leukotrienes, serotonin, and substance P may sensitize and/or activate nociceptors. Receptor activation leads to action potentials that are transmitted along afferent nerve fibers to the spinal cord.
Pain Management- Nociceptive pain:
The body modulates pain through several processes.
The endogenous opiate system consists of neurotransmitters (e.g., enkephalins, dynorphins, and β-endorphins) and receptors (e.g., μ, δ, К) that are found throughout the CNS. Endogenous opioids bind to opioid receptors and modulate the transmission of pain impulses.
The CNS also contains a descending system for control of pain transmission. This system originates in the brain and can inhibit synaptic pain transmission at the dorsal horn. Important neurotransmitters here include endogenous opioids, serotonin, norepinephrine, γ-aminobutyric acid, and neurotensin.
Pain Management- Nociceptive pain
Pain Management- NEUROPATHIC PAIN/FUNCTIONAL PAIN NEUROPATHIC PAIN/FUNCTIONAL PAIN
Neuropathic and functional pain is often described in terms of chronic pain.
Neuropathic pain (e.g., postherpetic neuralgia, diabetic neuropathy) is a result of nerve damage,
functional pain (e.g., fibromyalgia, irritable bowel syndrome, tension-type headache) refers to abnormal operation of the nervous system.
Pain Management the sensation of pain, is composed of four
basic processes:
Transduction
Transmission
Modulation
Perception
Perception is the conscious awareness of painThe perception of pain involves not only nociceptive processes, but also physiologic and emotional responses which contribute significantly to the sensation ultimately experienced by the person
Pain ManagementTreatment ImplicationsOnce these processes are considered, the
goal of therapy will be to reduce the actual perception of pain
This often requires multiple modalities to interrupt transmission at different levels
For example, the management of a painful chronic condition may include treatment with:
1. an opiate (e.g., morphine) to reduce ascending pain transmission,
2. a non steroidal inflammatory drug {NSAID} (e.g., ibuprofen) to reduce prostaglandin formation
3. A membrane stabilizing agent
Pain Management- Signs and Symptoms of PainGENERAL Patients may be in obvious acute distress
(trauma pain) or appear to have no noticeable suffering.
There is no specific laboratory test for pain
Chronic pain:Chronic pain can present similarly to acute
pain, often occurs without a timely relationship with a noxious stimulus.
Over time, the chronic pain presentation may change (e.g., sharp to dull, obvious to vague).
Chronic pain can be classified as either being associated with cancer (cancer pain) or from noncancer etiologies (chronic noncancer pain). Chronic pain may result in changes to the receptors and nerve fibers in the nervous system, often making treatment even more difficult.
Pain Management
Chronic Pain
Pain associated
with malignancy;
chronic malignant
pain
Chronic nonmalignant
pain
Pain Management
Pain ManagementMalignant PainPain associated with potentially life-
threatening conditions is often called malignant pain or simply cancer pain.
This type of pain includes both chronic and acute components and often has multiple etiologies. It is pain caused by:
the disease itself (e.g., tumor invasion, organ obstruction)
treatment (e.g., chemotherapy, extravasation, radiation, surgical incisions, constant catheter insertion)
diagnostic procedures (e.g., biopsy).
Pain ManagementChronic non malignant painDefined as Pain that is not associated with
a malignancy and lasts greater than six months or lasts beyond the expected healing period
The development of treatment guidelines is difficult because of the heterogeneity of the causes
Because chronic pain affects many aspects of the patients life, a multidisciplinary approach that addresses effective drug therapy and comprehensive rehabilitation often provides greater relief to the patient than drug therapy alone
Pain Management- Signs and Symptoms of PainAcute pain can be described as: sharp or dull, burning, shock-like, tingling, shooting, radiating, fluctuating in intensity, varying in location, occurring in a timely relationship with an
obvious noxious stimulus.
Pain Management- Signs and Symptoms of Pain
Pain Management- Patient assessmentEffective analgesic therapy begins with an
accurate assessment of the patientThe pain intensity and pain distress scales
can help clinicians assess painIt is important to gather details about the
pattern, duration, location, and character of the pain
Factors that relieve pain should be evaluated
Factors that aggravate pain should be identified
Pain Management- Patient AssessmentPain is always subjective; thus pain is best
diagnosed based on patient description, history, and physical exam.
A baseline description of pain can be obtained by assessing PQRST characteristics (palliative and provocative factors, quality, radiation, severity, and temporal factors).
Attention should be given to mental factors that may lower the pain threshold (anxiety, depression, fatigue, anger, fear).
Behavioral, cognitive, social, and cultural factors may also affect the pain experience and description.
Pain Management- Patient Assessment
Pain Management- Patient Assessment
Pain Management Patient Assessment
Pain Management- Treatment Options
Pain Manageme
nt
Non- Pharmacolo
gical
Pharmacological
Pain Management- Nonpharmacologic TherapyNonpharmacologic TherapyVarious nonpharmacologic therapies have been
found to be beneficial in the management of acute and chronic pain, including:
physical manipulation, application of heat or cold, massageexercise.Transcutaneous electrical nerve stimulation
(TENS) has been used in managing both acute and chronic pain (e.g., surgical, traumatic, neuropathy, and musculoskeletal pain).
evidence regarding long-term benefit is limited. has not gained widespread acceptance.
Pain Management- Nonpharmacologic Therapypsychological interventions for the
treatment of acute pain are not used widelySimple interventions (e.g., education or
introductory information about sensations to expect after certain procedures) reduce patient distress & greatly reduce pain after procedure
Other techniques, including relaxation training, imagery, and hypnosis, have proven effective in the management of postprocedure pain and in cancer-related pain.
cognitive behavioral therapy and biofeedback also may be useful in managing chronic pain.
Pain Management- Pharmacological Management General treatment principlesEffective analgesic therapy begins with an
accurate assessment of the patient Mild acute pain is often self limiting, or can
be managed with nonopoid agents on a regular schedule
Clinicians should provide adequate analgesics according to scenario, as pain often goes under treated
Pain Management- Pharmacological Management - General treatment principles Severe acute pain should always be
aggressively managed, even before a definitive cause is known EXCEPT
Patients with traumatic head injury; analgesics should be withheld until a full neurological work up can be done
Patients with acute abdominal pain; until a diagnosis has been made ( as the analgesic might make matters worse)
EG- Patient with severe abdominal pain; prescribed analgesic excreted renally- turns out he has kidney stone!!!
Pain Management- Pharmacological Management- General treatment principles When treating chronic pain, elimination and
prevention of pain is best accomplished by using analgesics at a fixed time interval ( time contingent) rather than on an “as needed” basis
Analgesics prescribed on a schedule to avoid possibility of: (i) higher daily dosage (ii) inadequate pain relief
In severe acute or malignant pain scheduled analgesics alone may not be adequate without additional analgesics for breakthrough episodes
Pain Management- Pharmacological Management- General treatment principles
Patient education
Anxiety and guilt often complicate the management of pain, therefore proper patient education is important
Pain Management- Pharmacological Management- General treatment principles Non-Steroidal Anti-inflammatory drugs;
(NSAID)Exact mechanism of NSAID analgesia is yet
to be elucidated, however its presumed that they exert their analgesic effect by:
Inhibiting prostaglandin synthesis in the periphery; however the NSAID analgesic efficacy does not correlate entirely with its capacity for prostaglandin inhibition in the periphery
Central in origin, and involves (i)substance P receptors of the neurokinin 1 type and (ii) glutamate receptors of the NMDA type (iii) central inhibition of prostaglandin synthesis
Pain Management- Pharmacological Management- General treatment principles Opiates: Opiates can attach to one or more of five
opioid receptors: the μ, δ, К, ε, σ The pharmacologic activity of opioids depends
on their affinity for opiate receptors.Therapeutic activities and side effects range from those exhibited by the opiate agonists (e.g., morphine) to those seen with the opiate antagonists (e.g., naloxone).
Opiates produce analgesia by three main mechanisms:
Presynaptically, opioids reduce the release of inflammatory transmitters
Opiates also can reduce the activity of output neurons
Opiates also inhibit neuronal activity via GABA and enkaphalin neurons in the substantia gelatinosa
Pain Management- Pharmacological Management- General treatment principles Opioids are more effective for treating
severe pain than non-opioid analgesics such as NSAID although the range of potencies is wide for this class of medicines
They are generally recommended for moderate to severe pain intensity and are used in chronic pain syndromes that are refractory to other agents
Morphine dosage requirements vary with the severity of pain, individual perceptions of pain, age, opioid tolerance or previous exposure, and the presence of concomitant diseases
The administration of opioid analgesics is frequently complicated by the need to convert between different routes of administration or different opioid formulations
The clinician must make sure equipotent doses are given, consulting appropriate references
Naloxone is used for reversal of opioid induced respiratoy depression
Pain Management- Pharmacological Management- General treatment principles
Pain Management- Pharmacological Management- General treatment principles
Side effects of opioidsRespiratory depressionLocal whealing at injection site due to
histamine releaseAllergic reactions, cross manifest within
same chemical class ( phenanthrenes, phenylpiperidines, phenylheptanones or diphenylheptanes) but not between classes
Nausea, Vomiting minimized by antihistamines
Itching
Pain Management- Pharmacological Management- General treatment principles Constipation!!!!- suppressed peristaltic
action of colon, increase colonic and anal sphincter tone
Tolerance does not develop
Pain Management- Pharmacological Management- General treatment principles When opioid analgesics are initiated, a
stimulant laxative plus stool softener should also be given.
For patients receiving morphine around the clock especially postoperatively recommend:
Senna 8.6 mg daily in combination with docusate sodium 200mg twice daily
If constipation persists, osmotic laxatives, such as lactulose or sodium phosphate enema, may be added
These will draw water to the lumen of the bowel which will cause distention and peristalsis
Pain Management- Pharmacological Management- General treatment principles Analgesic adjuvant agentsAnalgesic adjuvant agents are often
prescribed concurrently with other drugs to enhance analgesia or to treat pain exacerbations
Most often used in the management of chronic pain, especially when
(i) dose of primary analgesic has been optimized
(ii) when underlying condition has progressed and is no longer adequately controlled by the primary analgesic agent
Pain Management- Pharmacological Management- General treatment principles Adjunct analgesic agents may be used as
the primary analgesic agent in the treatment of neuropathic pain syndromes, where the usefulness of opiates is under debate
Neuropathic pain does not respond to NSAID
Antidepressants are commonly used to treat neuropathic pain and pain associated with insomnia or depression
Anticonvulsants, antiarrythmics, α2- adrenergic antagonists, and the N-methyl D-aspartic receptor antagonists, as well as ketamine and dextromethorphan have been used to manage neuropathic pain with varying degrees of success
Pain Management- Pharmacological Management- General treatment principles Antihistamines as hydroxyzine and
promethazine are often prescribed postoperatively to augment the analgesic effects of opioid agents
These agents may be useful in alleviating opioid induced nausea and vomiting. They have extra pyramidal side effects, hence should not be used as substitutes for appropriate doses of opioid analgesics
Pain Management- Pharmacological Management- General treatment principles Patient Controlled Analgesia ( PCA) PCA is a technique whereby patients self-
administer narcotics by using a preprogrammed mechanical infusion device attached to tubing that delivers the drug to the patient through an IV or subcutaneous needle or catheter.
The patient presses down on a button to activate the PCA controller to deliver a preset dose of opiate medication
The controller is preprogrammed to establish “lock out” periods that prevent the pump from delivering a dose if the patient presses the button too often
There are safeguards to prevent overdose; by adjusting lockout period and drug concentration
Pain Management- Pharmacological Management- General treatment principlesAdvantages of PCA are: less nurse time and effort, no need to wait
for medication to arrive from pharmacy, and avoids to call nurse and administer the medication
Eliminates problem of unordered /unadministered dose
PCA commonly used after certain surgeries, for up till 3-5 days postoperatively, e.g. after caesarean section delivery
Fentanyl, hydromorphone, and morphine are the opiods used most frequently
Pain Management- Pharmacological Management- General treatment principles
Pain Management- Pharmacological Management- General treatment principles For renally compromised patients - Clcr
estimated 30mL/min:Avoid meperidineFor patients with compromised liver
function, but not documented cirrhosis:If must, Give opioid doses in small on
demand doses with careful monitoringAvoid timed dependent dosing because
of the risk of drug accumulation If oral opioid is to be used, methadone is
suitable, but not more than four times a day
Pain Management
Pain Management- Pharmacological Management –Initial Regimens