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