Pain

1
Pain

• Most common reason people seek health care
• Tissue damage activates free nerve endings (pain
  receptors)
• Generally indicates tissue damage

2
Pain

• Defined as whatever the patient says it is
• It exists whenever he or she says it does

3
Gate TheoryPg 122 Fig 9-1

• Injury results in release (from the tissues) of
• Bradykinin
• Histamine
• Prostoglandins
• Action potential along nerve fiber
• Activates pain receptor
• Enter the spinal cord via the dorsal horn
• If impulses can be stopped herepain stops

4
Gate Theory

• Brain can evaluate, identify and localize pain

5
Bradykinin

• Strongest pain producing substances
• May be involved in acute pain
• Prostglandins increase sensitivity to pain
• Chemical mediators activate and sensitize pain
  receptors or stimulate the release of pain
  producing substances

6
(No Transcript)
7
Endogenous Analgesia

• Activated by nerve signals or by morphine-like
  substances entering the brain
• Opiate receptors
• Endogenous peptides

8
Pain Treatment

• Often UNDER treated
• Cancer pain management in particular
• Not aimed at prevention of addiction
• Patient comfort
• Tolerance may occur
• Pg 123 (do not confuse with addiction)

9
Opiod Analgesics

• Moderate to severe pain
• Reduction of pain sensation
• Sedation
• Decreases emotional upset
• Most are schedule II

10
Opioid Analgesics

• Oral, IM, SQ, IV
• PO requires high doses
• Prevent or relieve acute or chronic pain
• Bind to opioid receptors in the brain and spinal
  cord and activate the endogenous system

11

• Agonist-binds to a receptor site and causes a
  response
• Partial agonist-binds to a receptor and causes
  only limited actions
• Antagonist-bind to a receptor and produce no
  response

12
AgonistsPrototype Morphine Sulfate

• Morphine and morphine like drugs
• Activity at Mu, Kappa, ??? Delta receptors
• Severe Chronic Pain
• IV, IM, SQ, Suppository, Epidural,, PO
• Impaired kidney function may cause prolonged drug
  action and accumulation
• Nonceiling drug

13
PrototypeCodeine

• PO onset 15-30 minutes duration 4-6 hours
• Naturally occurring opium alkaloid
• ANTI-TUSSIVE
• Analgesic
• Milder adverse effects than morphine
• May be combined with Acetaminophen

14
Contraindications

• Respiratory depression
• Chronic lung disease
• Liver or kidney disease
• Prostatic hypertrophy
• Increased ICP

15
Agonist/AntagonistPrototype Nalbuphine (Nubain)

• Agonist activity at some sites and antagonist at
  others
• Low abuse potential
• Potent analgesics
• May produce withdrawal symptoms in those with
  opiate dependence
• Synthetic

16
Opioid AntagonistPrototype Naloxone (Narcan)

• Reverse or block analgesia, respiratory
  depression
• Onset within minutes and last 1-2 hours
• Shorter duration than opioids
• May give repeated injections

17
(No Transcript)
18
WithdrawalPg 125

• Anxiety, aggressiveness, restlessness,
  lacrimation, rhinorhea, perspiration, pupil
  dilation, piloerection, elevated body temp,
  diarrhea, BP
• Begin within few hours of last dose
• Early recognition and treatment key

19
Side Effects Assessments

• Respiratory depression
• Hypotension
• N V
• Constipation

• Monitor respirations
• Orthostatic pressures
• BP
• Bowel regimen

20
Teaching

• No Etoh
• Do not increase dose (unless Rxd)
• Stay in bed 30-60 minutes after receiving
• No heavy machinery
• High fiber foods increase fluids

21
Non Opioid Analgesics

• Analgesic, Antipyretic,
• Anti-inflammatory Drugs
• Acetylsalic Acid (Aspirin)
• Acetominophen (Tylenol)
• Ibuprofen (Motrin)

22
PrototypeAcetominophen

• Does not cause N V or GI bleeding
• Does not interfere with clotting
• Lacks anti-inflammatory activity
• Metabolized in liver
• Alters pain perception

23
Side Effects

• Hepatic necrosis (Acute overdose)
• Nephropathy (Chronic overuse)
• Liver toxicity increase with alcohol ingestion!

24
Mucolytic Prototype Acetylcysteine (Mucomyst)

• Antidote to Acetaminophen overdose
• Give PO
• Must be given within 24 hours
• Bad smell
• 17 doses
• Pg 132

25
Activated Charcoal

• May be given for an overdose of Acetaminophen

26
Other NSAIDS
27
Arachidonic Acid Pathway

• Released after injury
• Metabolized
• Both paths result in inflammation and pain

28
GI Distress

• Prostaglandins maintain the integrity of stomach
• Inhibition sets up
• Ulceration
• GI bleeds
• Misoprostol

29
PrototypeASA (Aspirin)

• Inhibits the synthesis of prostaglandins
• Non selective COX inhibitor
• Antiplatelet and Antipyretic
• Prevent sensitization of pain receptors to
  various chemical substances

30
Contraindications

• PUD
• GI or other bleeding disorders
• Hypersensitivity
• Impaired renal function
• Children with viral infections (pg 671)
• Intoxication (table 42-2)

31
PrototypeIbuprofen (Motrin)

• Anti-inflammatory agent
• OTC
• May be better tolerated than aspirin but work in
  a similar fashion
• Hypersensitivity may occur in people with allergy
  to aspirin
• Contraindications similar to ASA (except Reyes)

32
Selective COX-2 InhibitorPrototype Celecoxib
(Celebrex)

• Designed to relieve pain, fever, and
  inflammation
• Fewer side effects than older NSAIDS
• Contraindicated with ulcers, GI bleeds, asthma,
  severe renal impairment, allergy to other NSAIDS

33
Feverfew

• Relieves HA, fever, and menstrual irregularities
• Can increase bleeding with aspirin, dipyridamole,
  warfarin
• Contraindicated in pregnant patients,
  breastfeeding, and children lt 2 y/o
• http//www.merck.com/pubs/mmanual_home2/sec02/ch01
  9/ch019a.htm