1. 1 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Chapter 4 PAIN

2. 2 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain  Unpleasant sensation  Discomfort caused by stimulation of pain receptors  Body defense mechanism  Warning of a problem  Complex mechanisms  Many not totally understood  Subjective scales  Developed to compare pain levels over time

3. 3 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Causes of Pain  Inflammation  Infection  Ischemia and tissue necrosis  Stretching of tissue  Stretching of tendons, ligaments, joint capsule  Chemicals  Burns  Muscle spasm

4. 4 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Somatic Versus Visceral Pain  Somatic pain  From skin (cutaneous)  Bone muscle  Conducted by sensory fibers  Visceral pain  Originates in organs  Conducted by sympathetic fibers  May be acute or chronic

5. 5 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Pathways  Nociceptors (pain receptors) are free sensory nerve endings.  May be stimulated by:  Temperature  Extremes of temperature  Chemicals  Examples: acids, bradykinin, histamine, prostaglandin  Physical means  Example: pressure

6. 6 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain (Cont.)  Pain threshold  Level of stimulation required to elicit a pain response  Usually does not vary among individuals  Pain tolerance  Ability to cope with pain  Culturally related  Varies among individuals

7. 7 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Pathways  Nociceptors  Stimulated by  Thermal means: extreme temperatures  Chemical: For example, acids or chemicals produced by body (e.g., bradykinin, histamine, prostaglandin)  Physical: pressure

8. 8 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Fibers  Afferent fibers  Myelinated A delta fibers  Transmit impulses very rapidly  Acute pain  Sudden, sharp, localized  Unmyelinated C fibers  Transmit impulses slowly  Chronic pain  Diffuse, dull, burning, or aching sensation

9. 9 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Pathways (Cont.)  Dermatome  Area of skin innervated by a specific spinal nerve  Somatosensory cortex → “mapped”  Corresponds to source of pain stimuli  Reflex response  Involuntary muscle contraction away from pain source  Involuntary muscle contraction to guard against movement

10. 10 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Pathways (Cont.)  Spinothalamic bundle in the spinal cord  Neospinothalamic tract → fast impulses; acute pain  Paleospinothalamic tract → slow impulses; chronic, dull pain  Spinothalamic tracts connect with reticular formation of brain

11. 11 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Pathways (Cont.)  Somatic sensory area in the cerebral cortex located in the parietal lobe  Perception and localization of sensation  Hypothalamus and limbic system  Emotional factors  Communication with other regions of the brain to integrate responses  Reticular activating system (RAS)  Reticular formation in the pons and medulla  Awareness of incoming brain stimuli

12. 12 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Pathways (Cont.)

13. 13 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Physiology of Pain and Pain Control  Gate control theory  Control systems, “gates” built into normal pain pathways  Can modify pain stimuli conduction and transmission in the spinal cord and brain  Gates open  Pain impulses transmitted from periphery to brain  Gates closed  Reduces or modifies the passage of pain impulses

14. 14 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Control―Gate Open

15. 15 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Control―Gate Closed

16. 16 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Control  Application of ice  Impulses from temperature receptors close gates.  Transcutaneous electrical nerve stimulation (TENS)  Increases sensory stimulation at site, blocking pain transmission  Opiate-like chemicals (opioids)  Secreted by interneurons of the CNS (endogenous)  Block conduction of pain impulses to the CNS  Resemble morphine  Enkephalins, dynorphins, beta-lipoproteins

17. 17 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Signs, Symptoms, and Diagnosis of Pain  Location of pain  Descriptive terms  Aching, burning, sharp, throbbing, widespread, cramping, constant, periodic, unbearable, moderate  Timing of pain  Association with an activity  Physical evidence of pain  Pallor and sweating  High blood pressure, tachycardia

18. 18 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Signs, Symptoms, and Diagnosis of Pain (Cont.)  Nausea and vomiting  May occur with acute pain  Fainting and dizziness  May occur with acute pain  Anxiety and fear  Frequently evident in people with chest pain or trauma

19. 19 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Signs, Symptoms, and Diagnosis of Pain (Cont.)  Clenched fists or rigid faces  Restlessness or constant motion  Guarding area to prevent stimulation of receptors

20. 20 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Young Children and Pain  Infants respond physiologically  Examples: tachycardia, increased blood pressure, facial expressions  Great variations in different developmental stages:  Different coping mechanisms  Range of behavior  Often have difficulty describing the pain  Withdrawal and lack of communication in older children

21. 21 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Referred Pain  Source may be difficult to determine.  Pain may be perceived at site distant from source  Characteristic of visceral damage in the abdominal organs  Heart attack or ischemia in the heart

22. 22 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Location of Referred Pain

23. 23 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Phantom Pain  Usually in adults  More common if chronic pain has occurred  Can follow an amputation  Pain, itching, tingling  Usually does not respond to common pain therapies  May resolve within weeks to months  Phenomenon not fully understood

24. 24 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Pain Perception and Response  Pain tolerance  Degree of pain, intensity, or duration  May be increased by endorphin release  May be reduced because of fatigue or stress  Varies among people in different situations  Pain perception  Subjective but can be compared from day to day in same person  Response to pain  Influenced by personality, emotions, and cultural norms

25. 25 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Acute Pain  Usually sudden and severe, short term  Indicates tissue damage  May be localized or generalized  Initiates physiologic stress response  ↑ Blood pressure and heart rate; cool, pale, moist skin; ↑ respiratory rate; ↑ skeletal muscle tension  Vomiting may occur.  Strong emotional response may occur.

26. 26 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Chronic Pain  Occurs over extended time; may be recurrent  Usually more difficult to treat than acute pain  Often perceived to be generalized  Individual may be fatigued, irritable, depressed  Sleep disturbances common  Specific cause may be less apparent.  Appetite may be affected.  Can lead to weight gain or loss

27. 27 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Chronic Pain (Cont.)  Frequently affects daily activities  Accommodation and pacing of activities may be required.  Periods of acute pain may accompany chronic pain conditions.  Usually reduces tolerance to additional pain

28. 28 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Comparison of Acute and Chronic Pain

29. 29 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Headache: Types and Causes  Congested sinuses, nasal congestion, eye strain  Muscle spasm and tension  From emotional stress  In temporal area  Temporomandibular joint syndrome  Migraine  Abnormal blood flow and metabolism in the brain  Intracranial headaches  Increased pressure inside the skull

30. 30 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Headache: Types and Causes (Cont.)  Central pain  Caused by dysfunction or damage to the brain or spinal cord  Neuropathic pain  Caused by trauma or disease involving the peripheral nerves  Ischemic pain  Results from a profound, sudden loss of blood flow to an organ or tissue  Cancer-related pain  Caused by advance of the disease; pain associated with treatment; result of coexisting disease

31. 31 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Methods of Managing Pain  Remove cause of pain as soon as possible  Use of analgesic medications  Orally  Parenterally (injection)  Transdermal patch  Classified by ability to relieve  Mild pain  Moderate pain  Severe pain

32. 32 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Analgesic Drugs

33. 33 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Methods of Managing Pain (Cont.)  Sedatives and antianxiety drugs  Adjuncts to analgesic therapy  Promote rest and relaxation  May reduce dosage requirements for analgesic  Chronic and increasing pain  May occur in cancer  Stepwise fashion to reduce pain  Tolerance to narcotics develops over time  Increase dose requirements  New drug may be required

34. 34 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Methods of Managing Pain (Cont.)  Severe pain  Patients administer medication, as needed.  Patient-controlled analgesia (PCA)  Lessens overall consumption of narcotics  Intractable pain  Cannot be controlled with medication  Surgical intervention is a choice.  Rhizotomy  Cordotomy  Injections

35. 35 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Anesthesia  Local anesthesia  Injected or applied to skin or mucous membranes  Spinal or regional anesthesia  Blocks pain from legs or abdomen  General anesthesia  Causes loss of consciousness (gas or injection)  Neuroleptanesthesia  Patient can respond to commands.  Relatively unaware of procedure, no discomfort

36. 36 Copyright © 2014, 2011, 2006 by Saunders, an imprint of Elsevier, Inc. Anesthetics