Pain Management Flashcards
Why is pain considered the 5th vital sign?
Due to unsatisfactory pain relief
No reliable marker for pain
What is the most common sx prompting patients to seek medical attention?
Pain
What type of pain is described as a transient pain in response to a noxious stimulus at nociceptors that are located in cutaneous tissue, bone, muscle, connective tissue, vessels, and viscera
Nociceptive pain
What type of pain is described as when tissue damage occurs; pain hypersensitivity occurs to prevent contact or movement of injured part until healing is complete?
Inflammatory pain
What type of pain is described as Spontaneous pain and hypersensitivity to pain associated with damage to or pathologic changes in peripheral nervous system
Neuropathic pain
What type of pain is described as pain sensitivity due to an abnormal processing or function of CNS in response to normal stimuli?
Functional pain
What is involved in stimulation of the pathophysiology of nociceptive pain?
injury results in release of bradykinins, potassium, PROSTAGLANDINS, histamine, leukotrienes, serotonin, and substance P which sensitize or activates nociceptors
What is involved in transmission of the pathophysiology of nociceptive pain?
Impulse transmitted along sparsely myelinated A-δ fibers (responsible for sharp well localized pain) and unmyelinated C fibers (producing dull, aching, burning and diffuse pain). Fibers synapse in dorsal horn of spinal cord releasing variety NT (Glutamate, substance P)
What is involved in perception of the pathophysiology of nociceptive pain?
Transmission continues along spinal cord to thalamus where pain is precieved
What is involved in modulation of the pathophysiology of nociceptive pain?
complex process; endogenous opiate system
What is involved in inflammation pathophysiology?
The changes that occur in response to tissue injury or insult- leading to pain, redness, heat, swelling, and +/- loss of function.
Produced by interactions w/ inflammatory mediators derived from leucocytes or damaged tissues. Ex: Histamine, Kinins (bradykinin), Neuropeptide (substance P), Cytokines (interleukins), Arachidonic acid metabolites (eicosanoids)
What are inflammatory mediators derived from leucocytes or damaged tissues?
Histamine Kinins (bradykinin) Neuropeptide (substance P) Cytokines (interleukins) Arachidonic acid metabolites (eicosanoids)
What are the alterations of local blood vessels and what do these changes result from?
Result from alterations in local blood vessels (trauma) or antigens (viral, bacterial, etc)
Dilation of blood vessels
Increased permeability
Increased receptiveness for leukocytes- leukotriene- chemotatic response : accumulation of inflammatory cells (polymophonuclear neutrophil, leukocytes, macrophages, lymphocytes, basophils and eosinophils also accumulate depending on the type of inflammation)
Arachodonic acid
Disturbance of the phospholipids of the cell membrane metabolizes arachidonic acid by the enzyme phospholipase
Metabolized further by cyclooxygenase to produce prostaglandins, thrombozane, and prostacyclin (prostanoids)
and by lipoxygenase to produce leukotrienes
Disturbance of the phospholips of the cell membrane mobilized arachidonic acid by what enzyme?
Phospholipase A2
Arachidonic acid is metabolized by cyclooxygenase to produce what?
Prostaglandins
Thromboxane
Prostacyclin (collectively knowns as prostanoids)
Arachidonic acid is metabolized by lipoxygenase to produce what?
Leukotrienes
What are the 2 enzyme isoforms of cyclooxygenase?
Cox-1 and Cox 2
Cox-1
In most tissues- platelets, gastric mucosa, renal vasculature
Involved in physiological cell signaling
Most adverse effects w/ NSAIDs occur because of inhibition of cox-1
Cox-2
Induced at sites of inflammation & produces the prostanoids involved in the inflammatory responses
Analgesic and anti-inflammatory effects of NSAIDs are largely a result of inhibition of Cox-2
Eicosanoids
Involved in most inflammatory reactions
inflammatory therapy is based on the manipulation of their biosynthesis
Polyunsaturated fatty acids produced by arachidonic acid
What are the prostanoids eicosanoids?
Prostaglandinds (PGD2, PGE2, PGF2)
Thomboxane A2 (TXA2)
Prostacyclin (PGI2)
What is the action of inflammation for the prostaglandins?
Vasodilation, vascular permeability, edema, stimulation of other inflammatory mediators
What is the action of inflammation for the thomboxane A2 (TXA2)?
Platelet aggregation and vasoconstriction
What is the action of inflammation of prostacyclin (PGI2)?
Inhibition of platelet aggregation and vasodilation
What are the leukotriene eicosanoids?
LTB4
LTC4
What are the actions of inflammation of leukotrienes?
Increase vascular permeability, promote leukocyte chemotaxis, contraction of bronchial smooth muscle.
What is acute pain usually result from?
An injury or surgery and is usually self limited
What does poorly treated acute pain result in?
Tachypnea Tachycardia Pallor Diaphoresis Pupil Dilation Psychological Stress
What is chronic pain?
Pain that persists beyond expected normal time for healing and serves no physiologic purpose
It can be maladaptive
What are the types of chronic pain?
Malignant- associated with life threatening disease and lasting more than 6 months
Non-malignant- not associated with life threatening disease and lasting more than 6 months (Neuropathic- involving disease of CNS and PNS)
What does PQRST stand for in pain assessment?
Pallative/provactive Quality Radiation Severity Temporal
What is the pain algorithm for acute mild/moderate pain?
- NSAIDS or APAP
2. Opioids
What is the pain algorithm for acute sever pain
- Opioids
2. Add NSAIDs or APAP
What is the pain algorithm for chronic visceral pain?
- Opioids for sever
2. Add adjuvants (TCA- tricyclic antidepressant or AED-antiepilectic drugs)
What is the pain algorithm for chronic inflammatory pain?
- APAP or NSAIDs
2. Long acting opioids
What is the pain algorithm for chronic neuropathic pain? Central and peripheral?
Central- clonidine or baclofen
Peripheral- TCA or AED, lidocaine, SSRI or SNRI, Long acting opiods
What is pain algorithm for chronic functional pain?
- TCA or Tramadol
2. SSRI/SNRI or preganalin
Nonsteroidal anti-inflammatory agents- MOA
Inhibition of cyclooxygenase and resulting inhibition of prostaglandin synthesis, producing three major clinical actions- analgesia, anti-inflammatory, antipyretic
What nonsteroidal anti-inflammatory agents have irreversible inhibition?
Aspirin which causes acetylation of the active site
What is nonsteroidal anti-inflammatory agents have competitive inhibition?
Ibuprofen which acts as a competitive substrate
What is the mechanism of action of the clinical action of Analgesic?
- Peripheral effect due to the inhibition of prostaglandins synthesis at the site of pain and inflammation
- Prostaglandins do not produce pain directly, but sensitize nerve endings to other inflammatory mediators (bradykinin-substance , histamine, 5-HT) amplifying the pain message.
- NSAIDs are effective where inflammation is involved.
- Small component of analgesic action is a consequence of reducing prostaglandin synthesis in the CNS.
What is the mechanism of action of the clinical action anti-inflammatory action?
- Prostaglandins produce increased vasodilation, vascular permeability & edema of inflammatory reaction-thus inhibition of prostaglandins reduces this part of the inflammatory reaction.
- NSAIDS do not inhibit the numerous other mediators involved in an inflammatory reaction
What are the clinical effects of NSAIDs?
Analgesic
Anti-inflammatory action
Antipyretic Action
What is the mechanism of action of the clinical action antipyretic action?
- During fever, leukocytes release inflammatory pyrogens-part of immune response, which act on thermoregulatory center in the hypothalamus to increased body temp.
- Theory-this effect is mediated by an increase hypothalamic prostaglandins (PGEs) causes increase in body temp
- NSAIDs do not affect temp under normal circumstance or in heat stroke.
NSAIDs- Indications
- Musculoskeletal and joint disease (Strains, sprains, rheumatic problems, arthritis, gout)
- Analgesia for mild to moderate pain relief including HA, dysmenorrhea, sunburn
- Symptomatic relief of fever
NSAIDS- GI effects
-Prostacyclins and prostaglandins inhibit gastric acid secretion and increase the synthesis of protective mucus & bicarbonate in the stomach and small intestine.
-NSAIDs inhibit PG synthesis & produce an increase in gastric acid secretion & diminished mucus and bicarb protection.
-May produce epigastric distress, ulceration and/or hemorrhaging. Avoid in peptic ulcer dz
MISOPROSTOL- PGE analog used to tx NSAID induced GI damage
What is misoprostol used for?
Dilation of the cervix
NSAIDS- Kidney effects
- Prostaglandin synthesis normally antagonized intrarenal effects of vasoconstrictors
- This can lead to: retention of sodium and water, edema and hyperkalemia, and high doses should be avoided if heart or renal problems.
NSAIDS- adverse effects
GI bleeds
Tinnitus
Edema and hyperkalemia
Pts w/ CHF, hepatic cirrhosis, and renal insufficiency may already have a decrease in renal blood flow and GFR-> unopposed to vasoconstriction
NSAID- contraindictations
GI bleeds
Hypersensitivity to NSAIDS
Caution- in patients w/ asthma, renal impairment and thrombocytopenia.
Avoid at least one wk prior to surgery
Aspirin-MOA
- Rapidly hydrolyzed to salicylic acid in the plasma, both agents responsible for the pharmacologic effects of inhibiting cyclooyenase
- Anti-coagulant (Antiplatelet) effect due to inhibition of thromboxane A2 (1st step in thrombus formation) production in platelets leading to ineffective platelets for clotting.
Aspirin- Therapeutic uses
CV- prophylactially to decrease in incidence of TIAs, MIs, unstable angina
Antipyretic & analgesic
Colon cancer prevetion w/ chronic use
Anti-inflammatory
Aspirin- Adverse Effects
Salicylism- poisoning w/ salicylates- N/V, hyperventilation, HA, mental confusion, dizziness, & TINNITUS. W/ larger doses restlessness, delirium, hallucinations, convulsions, coma, respiratory & metabolic acidosis
- Respiratory: therapeutic dose = increased alveolar ventil -> increased CO2 and respirations. Higher dose= hyperventilation leads to resp alkalosis; compensated by kidney. Toxic dose=central respiratory paralysis->resp acidosis cue to continued CO2 production.
- REYE’s SYNDROME- ASA w/ viral infections led to hepatitis and cerebral edema-often fatal
- Hypersensitivity=urticaria, bronchoconstriction, angioedema
What is salicylism?
poisoning w/ salicylates- N/V, hyperventilation, HA, mental confusion, dizziness, & TINNITUS. W/ larger doses restlessness, delirium, hallucinations, convulsions, coma, respiratory & metabolic acidosis
What is Reye’s Syndrome?
ASA w/viral infections led to hepatitis and cerebral edema-often fatal.
Aspirin- drug interactions
- Increased hemorrhage w/ heparin and oral anticoagulants
- Decreased urate excretion w/ probenecid (contraindication in gout pts)
- Antacids decrease rate of absorption
- Ibuprofen inhibits antiplatelet effect of low dose ASA
Diflunisal (Dolobid)
Diflurophenyl derivative of salicylic acid (not metabolized to salicylic acid -> no salicylate intoxication
More potent than ASA
No antipyretic activity, doesn’t cross BBB
Name the NSAIDs we should know for this class?
Ibuprophe (Motrin) Oxaprozin (Daypro) Naproxen (Naprosyn,aleve) Indomethacin (Indocin) Sulindac (Clinoril) Diclofenae (voltaren) Etodolac (Lodine) Nabumatone (Relafen) Piroxicam (Feldene) Meloxicam (Mobic) Aspirin