Pain Flashcards
People at risk for under treatment of pain.
Elderly Children Minorities Underinsured Women Those with a history of drug abuse.
Patient related barriers to pain relief
Reluctant to report pain due to:
Fear of opioids and their side effects such as constipation, sedation, addiction, cognitive impairment
Wanting to be a good patient
Fear of loss of effectiveness
Fear that morphine means death
Nociceptive Pain
Activation of nociceptors which are pain sensitive structures.
Types of nociceptive pain
Somatic and viceral pain
Somatic pain
Cutaneous and deep MSK
Well localized
Ex: Bone metastasis, incisional pain, spasm, muscle inflammation.
Visceral Pain
Infiltration, compression, distention or stretching of thoracic or abdominal viscera.
Ex: cirrhosis, pancreatic ca.
Poorly localized, deep, squeezing or pressure, cramping.
Associated with nausea, vomiting or diaphoresis.
May be referred to cutaneous sites that can be remote from lesion.
Shoulder pain associated with diaphragmatic lesio .
Neuropathic Pain
Injury to CNS or PNS
Plexopathies, cord compression, neuralgia, chemo induced neuropathies.
Sharp, shooting, electric shock, pressure.
Difficult to control.
Chronic pain
Longer than 3 months.
Adaptation of autonomic system means no increased HR or BP.
Poorly controlled may lead to depression, fatigue, anxiety, insomnia.
Limits interactions with others.
Limits goal achievement.
Contributed to desire of death.
Breakthrough Pain
Transient increase in pain to greater than moderate intensity occurring in the presence of a baseline pain of moderate intensity or less.
Incident Pain
Marked by a particular movement or activity.
NSAIDS
Inhibit cyclooxygenase leading to analgesia and decreased production of prostaglandins that protect the gastric mucosa and renal parenchyma increasing risk of GI symptoms and bleeding.
Step one on the WHO Pain ladder
Mild pain - 1-3
Non opioids plus coanalgesics if needed.
Step two on who Pain ladder
Moderate pain - 4-6
Low dose opioid and nonopioid or coanalgesic
Step 3 on the WHO Pain ladder
Severe pain - 7-10
Opioids titrated to pain relief plus nonopioids plus coanalgesics
Those at risk for NSAID renal failure
CHF, renal disease, cirrhosis with ascites, atherosclerotic HD, multiple myeloma.
Side effects of NSAIDS
Hypertension, sodium retention, edema, cardiovascular event risk,
What happens when partial agonists are given to patient who use full opioid agonists?
Withdrawal syndrome.
Why are partial agonists not recommended for chronic pain or progressing pain.
They have a ceiling dose and can cause withdrawal syndrome.
Why is methadone dangerous?
Long and variable half-life, plasma concentration rises slowly requiring a week or longer to reach steady state,, QT prolongation requiring EKG before use.
Equianalgesic dose when switching from another opioid to methadone.
Dose reduction by as much as 90 percent.
Methadone dosing in older adults or renal failure/hepatic failure
less frequent dosing, more conservative dose titrations.
Causes contributing to methadone induced cardiac arrhythmia or QT prolongation
Cardiac disease, other medications use with it that are QT prolongers, drugs that interact with methadone.
Types of pain that methadone is good for
Nociceptive pain and neuropathic pain that is unresponsive to other therapy.
Gastrointestinal side effects of opioids
Nausea, constipation, vomiting
Autonomic effects of opioids
postural hypotension, urinary retention, xerostomia
Cutaneous effects of opioids
Itching, sweating
CNS effects of opioids
Cognitive impairment, delirium, drowsiness, hyperalgesia, myoclonus, respiratory depression, seizures.
What is the most common opioid side effect
Constipation, and people do not gain tolerance.
Bowel regimen for opioid use
Stool softener and a bowel stimulant
What is used for refractory constipation
methylnaltrexone
What does methylnaltrexone do?
Antagonizes peripherally located opioid receptors and spares CNS effects of opioids producing analgesia.
How is methylnaltrexone given?
SC, resulting in BM within 90 min.
What can be done about nausea and sedation.
Common among initiation and fast upward titration. Most people gain tolerance within a week. Opioid rotation may be effective or stimulants may be added.
Why is respiratory depression rare?
Sedation precedes respiratory depression.
How do you give naloxone? What is the half-life of naloxone
Dilute 0.4mg in 10mL NS and give at a rate of 0.2mg IVP q 2 minutes. Half-life is 30 min.
Who is at increased risk from opioid induced respiratory depression
COPD, sleep apnea, sedating medications.
What is myoclonus
Uncontrolled spasm of muscle groups that may vary in intensity and may be progressive. It is dose related. May be related to metabolic disturbance such as renal compromise.
How do you treat myoclonus
Rotate to another opioid which may allow for dose reduction or give low dose benzo.
What is opioid induced hyperalgesia
When a person reports increasingly severe pain after an opioid increase.
How do you treat OIH
Taper the opioid, rotate the opioid, add an NDMA modulator and evaluate patient pain for next 24-48 hours.
What are co-analgesics?
Drugs that have a primary indication other than pain but have analgesic effects under certain circumstances.
Examples of coanalgesics
antidepressants, anticonvulsants, corticosteroids. Most common in treatment of neuropathic pain.
First-line coanalgesics
TCAs, dual reuptake inhibitors of serotonin and norepinephrine, calcium channel ligands, topical lido.
Ketamine
NMDA receptor activity. Narrow therapeutic window. Sub-analgesic doses.
Side effects of ketamine
hallucinations, memory problems, potential for abuse and addition.
Intravenous Lidocaine
Short isolated infusions, for long term pain relief in terminally ill patients.
Tricyclic antidepressants
Neuropathic pain.
Nortriptyline 10-25mg/QHS
Desipramine 10-25mg/QD
Side effects of TCAs
Anticholinergic
SNRIs
Neuropathic Pain
Venlafaxine 37.5mg PO QD
Duloxetine 30 mg PO QD
Side effects of SNRIs
Nausea, Dizziness
Benzodiazepines
Neuropathic Pain
Clonazepam 0.5-1mg PO QHS BID or TID
Side effects of Benzos as pain meds
Dizziness and lower extremity edema
GABA
Gabapentin 100mg PO TID
Pregabalin 75mg PO BID
Side effects of GABA as pain meds
Dizziness and LE Edema
Corticosteroids
Cord compression, bone pain, neuropathic pain, visceral pain and pain crisis.
Dexamethasone 2-20mg PO/IV/SC daily
Prednisons 15-30mg PO TID or QID
Side effects of Corticosteroids as pain meds
Steroid psychosis delirium, dyspepsia
Local anesthetics
Lidocaine patch 5% 12 hours on/off - may cause skin erythema Lidocaine infusion (IV/SC) may cause cardiac changes or perioral numbness
Biphosphenates
Pamidronate 60-90mg Q 2-4 weeks
Zolendronic acid 4mg Q3-4 weeks
May cause pain flair and osteonecrosis.
Risks of neural blockage
sensory loss, altered bowel, bladder function, weakness, altered sexual function, intravascular injection, hematoma, fatigue, over sedation.
How much is a rescue dose?
10-15% of the patients 24 hours ATC dose.
When do you consider opioid rotation?
Two or MORE side effects excluding constipation.
What are withdrawal side effects?
lacrimation, rhinorrhea, yawning, goosebumps, tremor, insomnia, diarrhea, irritability.
How do you prevent acute withdrawal syndrome?
Taper medications if ATC for a week or more. Give 25 percent of the previous 24 hours opioid dose.
Abberant drug behavior
Repeated episode of unsanctioned dose escalation, calling in early prescription renewals, lost medication.
