Physiology of pain and pain transmission by SANDWE T.K

1. PAIN
SANDWE T.K

2. At the end of the lecture/discussion students should be
able to acquire Knowledge and understanding of pain.
GENERAL OBJECTIVE

3. At the end of the lecture/discussion students should be able to;
• Define pain.
• Explain the simple physiology of pain.
• State the causes of pain.
• State the types of pain.
• Explain the management of pain.
SPECIFIC OBJECTIVES

4. • Pain occurs in all clinical settings, among different groups of patients
thus, the nurse has a central role in pain assessment and
management. To perform this role, the nurse should have a thorough
understanding of the physiological and psychosocial dimensions of
pain.
INTRODUCTION

5. Pain is a sensation where a person experiences
discomfort, distress or suffering due to overstimulation
of sensory nerves.
Definition of pain

6. • “Unpleasant sensory and emotional experience
associated with actual or potential tissue damage, or
described in terms of such damage
Or

7. PHYSIOLOGY OF PAIN

8. .

9. The peripheral nerves (transmition
stage)/perception of stimuli stage/receiving stage
• Pain basically results from a series of exchanges among three major
components of the nervous system: The peripheral nerves
(transmition stage)
• The peripheral nerves extend from the spinal cord to the skin,
muscles and internal organs. At the end we have different types of
nerve fibers with different functions and among them we have the
nociceptors

10. The peripheral nerves (transmition stage)
cont…
• These are receptors that detect actual or potential tissue
damage. We have millions of nociceptors in our skin, bones,
joints and muscles and in the protective membrane around
our internal organs.
• But their greatest concentration is in areas prone to injury,
such as our fingers and toes.
• When nociceptors detect a harmful stimulus they relay their
pain messages in the form of electrical impulses along a
peripheral nerve to the spinal cord and brain. Sensations of
severe pain are transmitted almost instantaneously

11. The spinal cord (transduction stage)
• The nerve fibres that transmit pain messages enter
the spinal cord in an area called the dorsal horn.
• There, they release chemicals (neurotransmitters) that
activate other nerve cells in the spinal cord, which
process the information and then transmit it up to the
brain.

12. The brain (interpretation stage)
• When messages of pain travel up the spinal cord, it arrives at the
thalamus — a sorting and switching station located deep inside the
brain.
• The thalamus quickly forwards the message simultaneously to
three specialized regions of the brain: the physical sensation region
(somatosensory cortex),
• the emotional feeling region (limbic system) and
• the thinking/memory/emotions region (frontal cortex or cingulate
system)

13. Descending control system
•The brain responds to pain by sending messages
that moderate the pain in the spinal cord the
descending control system.
•This system is active through out to inhibit pain
by producing endorphins.

14. Factors that influence pain perception
• Dimensions of feeling pain
1. Pain threshold
2. Pain tolerance
3. Reaction to pain

15. Factors
• Emotional and psychological state
• Memories of past pain experiences
• Upbringing
• Attitude
• Expectations
Beliefs and values
• Age
• Sex and Social and cultural influences

16. TYPES OF PAIN
Mild pain
Moderate pain
Severe pain
Phantom pain
Neurogenic pain
Referred pain
Acute pain
Chronic pain
Intractable pain
Nociceptive
Neuropathic

17. Acute pain
• Pain of short duration, usually less than 6 months
• It usually protective and has an identifiable cause
• It has limited tissue damage
• Physical manifestations include-increased heart rate,
respiratory rate, blood pressure, and anxiety .
Types of pain

18. Chronic Pain
• May start as acute pain but last longer beyond the normal time of recovery
usually more than 6 months
• Cause may not be known
• Physical manifestations include flat affect, reduced physical
movement/activity, fatigue and withdraw from others and social
interactions.

19. Idiopathic Pain
Chronic pain in the absence of an identifiable physical or
emotional cause.
Referred Pain
• Form of visceral pain which is felt in an area distant from the
from the site of stimulus

20. Psychogenic Pain
• Pain not caused by nociception but by psychological factors.
• Patient will usually report pain that does not match the
underlying disorder
• Its diagnosed after ruling out all the other causes of pain.

21. • Nociceptive :Pain caused by inflammed or damaged
tissue.
• Neuropathic :caused by damage to or malfunction of
the Nervous system

22. BENEFITS OF PAIN SENSATION
• 1. Pain gives warning signal about the existence of a
problem or threat. It also creates awareness of injury.
• 2. Pain prevents further damage by causing reflex
withdrawal of the body from the source of injury
• 3. Pain forces the person to rest or to minimize the
activities thus enabling rapid healing of injured part
• 4. Pain urges the person to take required treatment to
prevent major damage.

23. • Pain is subjective, no two persons experience pain in the same
way and no two painful events create identical responses or
feelings in a person.
• In order to be able to manage pain there is need to conduct a
pain assessment. Accurate pain assessment is an essential
element in effective pain management
MANAGEMENT OF PAIN

24. • Pain assessment mainly involves direct interview and
observation of the patient.
• The use of pain scales and physical examination completes the
assessment.
• Before assessment remember that the pt may use other words
other than pain to denote pain e.g. aching.

25. During assessment, consider the following characteristics of
pain.
Pattern of pain.
• Ask the patient about the onset of pain-for acute pain the
patient may know exactly while for chronic pain the patient may
not precisely identify the time of onset.
• Knowledge of onset can guide in identifying possible cause and
treatment strategies.

26. Location of Pain
• The area or location of pain assists in identifying the possible
cause and treatment too. Some individuals may specify the
precise location while others may simply say it’s hurting all over
.

27. Quality of pain
• Quality refers to the nature of pain e.g. neuropathic pain may be
described as burning, shooting or stabbing while nociceptive
pain may be described as sharp. Throbbing and cramping.

28. Associated symptoms
• Associated symptoms such as anxiety, fatigue or depression
may exacerbate or may be exacerbated by pain. Ask for
activities that improve or worsen the pain e.g. in
musculoskeletal pain movement and ambulation may worsen
pain while resting and immobilization of the affected part may
decrease the pain.

29. Intensity of Pain
• Assessing the severity and intensity of pain helps in identifying
the treatment strategies.
• Pain scales can be used to help the patient communicate the
intensity of pain.
Such scales include:
• Numerical pain intensity scales. On a scale of 0-10, patient
rates his pain. 0 stands for no pain, 5 moderate pain and 10
Worst possible pain.

30. • Descriptive pain intensity Scale-describes pain in terms
of no pain, mild pain, moderate pain, severe pain, Very
severe pain and worst possible pain.

31. • A widely used method of providing effective care is the nursing care
plan. With the use of a care plan the nurse is able to diagnose the
problem, plan for expected outcomes, implement interventions, state
reasons for the interventions, and evaluate the outcome.
NURSING CARE OF A PATIENT IN PAIN.

32. • Acute pain – Related to tissue injury from an incision site.
• Activity intolerance—Related to unrelieved pain.
• Ineffective coping—Related to lack of knowledge of possible methods
of coping.
Nursing Diagnosis.

33. • Outcomes and goals should be determined. A realistic outcome
should be established to control or maintain the client at desired
levels of pain and functioning.
Desired outcomes are that:
• Report acceptable pain levels.
• Perform daily activities without limitation related to pain.
• Increased patient comfort
Outcomes.

34. • Rest and relaxation
• To promote rest and relaxation ensure that there is no noise in the
environment.
• Plan your work in a way that procedures are carried out at almost the
same time.
• Alley anxiety
• Explain procedures to the patient. Encourage the patient to verbalize
their pain and fears. Reassure the patient that everything possible is
being done to minimize or provide relief .
NURSING MEASURES TO RELIEVE PAIN.

35. • Position
• Change of position may provide relief ( this depends on the cause of
pain) for the patient by reducing the pressure on the site.
• Diversional Therapy
• Can be done by providing books, news paper to read, music or
television. This will help in keeping the patients mind off the pain.
•

36. Local application
• A Warm or Cold compress can be applied. But care must be taken as
to not add further injury.
Analgesia
• Give the prescribed analgesics and document on the patient
treatment chart.

37. In today’s lecture we have discussed pain. The definition, and causes
of pain. We have also been able to look at the simple physiology of
pain, types of pain and the management of a patient in pain.
SUMMARY

38. We have come to the end of our lecture. Thank you for your attention
and participation.
CONCLUSION

39. • Anne W and Allison G (2010),Ross and Wilsom, Anatomy and Physiology
in health and Illness,11th edition, Edinburgh, London.
• Black,Hawks, (2005) Medical Surgical Nursing, Clinical Management for
positive outcomes, 18th Edition,Saunders, Elsevier inc. pages 276-301.
• Elaine N. Marieb (1989), Human anatomy Physiology,3rd edition, redwood
city, California.
•
• 4. Potter and Perry (2009),Fundamentals of Nursing 6th edition, st Louis
University School of Nursing,st Louis, Missouri.
•
REFERENCES