Pain

Pain

The word "pain" originates from the Latin word 'Poena" meaning a fine or a penalty. Pain is often described as an unpleasant sensation that can vary from mild, localized discomfort to severe distress.Emphasizes the highly subjective nature of pain

Definition

"Pain is an unpleasant sensory and emotional experience arising from actual or potential tissue damage or described in terms of such damage." -International Association for the Study of Pain (IASP), 2014
Pain is defined as "whatever the experiencing person says it is and existing whenever the person says it does." -Margo McCaffery (Nursing's Pain Pioneer)

Pain the fifth vital sign

The intent of the “pain the fifth vital sign” campaign (Presidential Address to the American Pain Society, 1996, Campbell) was to encourage doctors and nurses to listen to their patients and assess their pain. This was because health care professionals often ignored patients' suffering from pain.

Types of Pain

1. Pain based on Duration

Acute Pain
Chronic Pain

2. Based on Location

3. Based on Intensity

Mild pain
Moderate pain
Severe pain

4. Based on Etiology

a. Nociceptive pain

Somatic pain
Visceral pain

b. Neuropathic pain

Peripheral neuropathic pain
Central neuropathic pain

c. Psychogenic pain

1. Pain based on Duration

Acute Pain
Chronic Pain

Acute Pain

It is limited and often predictable in duration, such as postoperative pain and usually disappears as the wound heals. Acute pain is often described as 'sharp', 'stabbing' and 'shooting' by the patient. It is often reversible or manageable with sufficient treatment and the patient returns to the prepain state when the pain is relieved.

Chronic Pain

As per American Pain Society (2007), chronic pain is defined as pain that persists at least 3 months beyond the expected course of an acute injury or illness. However, more accepted duration for explaining the chronic pain more is >6 months or 1 month beyond the normal end of the condition causing the pain.

Chronic Cancer pain-Cancer pain is the pain caused by tumor progression and related pathological processes, invasive procedures.
Chronic Non cancer pain-The chronic pain resulted due to non-cancer disease condition. Chronic low backache is an example of chronic non-cancer pain.
Chronic Episodic pain- Pain that occurs sporadically over an extended duration of time is known as episodic pain. Pain episodes last for hours, days, or weeks. Examples are migraine headaches. Headache, Back pain, Joint pain, Stomach pain, Cardiac pain

2.Based on Location-

This classification of pain is based on the site at which the pain is located.

Non referred pain-Back pain or toothache, Stomach pain.
Referred pain-pain of Myocardial

3. Pain Based on Intensity

Pain scales can be used to assess the intensity of the pain. On the basis of pain intensity, pain can be classified as mild, moderate and severe.

Mild pain- It can be explained as nagging, annoying pain, but doesn't really interfere with daily living activities. Pain scale reading from 1 to 3 is considered as mild pain.
Moderate pain- It is considerable to be between mild and severe pain. A person can ignore such type of pain for a period of time but it interferes significantly with daily living activities. Pain scale reading from 4 to 6 is considered as moderate pain.
Severe pain- It is intense, excruciating and disabling pain. It makes a person unable to perform daily living activities. Pain scale reading from 7 to 10 is considered as severe pain.

4. Pain Based on Causes/Etiology

On the basis of etiology, the pain can be classified as nociceptive pain, neuropathic pain and psychogenic pain.

a. Nociceptive Pain-Nociceptive pain is perceived when an intact, properly functioning nervous system sends signals that tissues are damaged, requiring attention and proper care.

For example, the pain experienced following a burn alerts the person to avoid further damage by taking the hand away from thermal stimuli.

There are two types nociceptive pain on the basis of activation of nociceptors, i.e.,

Somatic
Visceral pain

Somatic pain- This is the pain that originates from the skin, muscles, bone, or connective tissues.

Somatic pain is often sharp, localized and may have a burning or pricking quality. The sharp sensation of a paper cut or sprained ankle are common examples of somatic pain.

Visceral pain- Visceral pain is pain that results from the activation of nociceptors of the thoracic, pelvic, or abdominal viscera (organs).

This pain is characterized by cramping, throbbing, pressing, or aching qualities.

For example, labor pain, angina pectoris or irritable bowel.

b. Neuropathic Pain

Neuropathic pain is caused by damaged or malfunctioning nerves due to injury, illness or undetermined reasons.

For example, diabetic peripheral neuropathy, phantom limb pain, spinal cord injury pain, trigeminal neuralgia, etc.

Peripheral neuropathic pain- This type of pain is due to damage to peripheral nervous system.For example, phantom limb pain, diabetic peripheral neuropathy.
Central neuropathic pain- Central neuropathic pain results from malfunctioning nerves in the CNS. For example, spinal cord injury pain, post-stroke pain.

c. Psychogenic Pain

Most patients with chronic pain experience varied degree of psychological distress.
Psychogenic pain can be defined as the pain that can be best explained by psychological problems. This does not mean that the individual is not actually experiencing the pain. Rather, the patient is truly suffering but the main cause somehow relates to the emotions or to some psychological process.

Pain Mechanism/Pain Physiology
Pain is a vital function of the human body, involving nociceptors and the CNS to transmit messages from noxious stimuli to the brain. Nociceptors are sensory fibers that are accountable for detecting harmful or potentially harmful noxious stimuli and conveying electrical signals to the nervous system.The neuron is the basic functional unit of the nervous system.

Nociceptors-A nociceptor ("pain receptor" ) is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. are present in skin, visceral organs, muscles, joints and meninges to detect a range of stimuli, which may be-

Mechanical-Mechanical nociceptors respond to excess pressure or mechanical deformation. They also respond to incisions that break the skin surface.
Thermal-Thermal nociceptors are activated by noxious heat or cold at various temperatures.
Chemical in nature.

Pseudounipolar neurons are sensory neurons that have no dendrites, the branched axon serving both functions. The peripheral branch extends from the cell body to organs in the periphery including skin, joints and muscles, and the central branch extends from the cell body to the spinal cord.

Nociceptors are of two main types-

A-delta fibers- These are the myelinated fibers, thus conduct more rapidly and convey messages of sharp and momentary pain.
C-fibers are nonmyelinated nerve fibers- C-fibres are the most common type of nociceptors and are slow to conduct and respond to noxious stimuli. Pain transmitted by C-fibers is usually dull in nature.

Process of Pain Mechanism

Nociception is the pain's physiological process by which information about tissue damage is communicated by nociceptors to the CNS. Nociception involves four processes-

1. Transduction-Transduction is the process of conversion of a mechanical, thermal, or chemical stimulation into a neuronal action potential. The transduction of pain signals occurs at the level of the peripheral nerves, mainly in the free nerve endings or nociceptors.

2. Transmission- Transmission is the process of movement of pain impulses from the site of transduction to the brain. Three events are involved in nociceptive signal transmission-

Transmission along peripheral nerve fibers to the spinal cord- The first order neuron extends the entire distance from the periphery to the dorsal horn of the spinal cord with no synapses.
Dorsal horn processing- Once the nociceptive signal arrives in the spinal cord, it is processed within the dorsal horn of the spinal cord. This processing includes the release of neurotransmitters bradykin, serotonin, histamin, substance. Prostaglandin sensitize nociceptors thereby enhancing the pain.
Transmission to the thalamus and the cerebral cortex- Nociceptive stimuli from the dorsal horn, are communicated to the third order neuron, primarily in the thalamus and several other areas of the brain. Fibres of dorsal horn projection cells enter the brain through several pathways, including the spinothalamic tract (STT) and spinoreticular tract (SRT).

3. Perception-It occurs when pain is recognized, defined and responded by the individual. In the brain, nociceptive input is recognised as pain. There is no single, precise location where pain perception occurs. Instead, pain perception involves several brain structures.

4. Modulation- Modulation includes the activation of descending pathways that exert inhibitory effects on the transmission of pain. Pain modulation refers to the process by which the body alters a pain signal as it is transmitted along the pain pathway and explains, at least in part, why individual responses to the same painful stimulus sometimes differ.

Effects of pain

Pallor
Increased blood pressure
Increased pulse
Increased respiration
Skeletal muscle tension
Diaphoresis
Nausea & vomiting
Weakness
Sleep disturbances
Unexpected weight loss
Loss of consciousness

Factors Affecting Pain

Perception of pain
Placebo effect
Sociocultural factors
Past experiences
Age
Anxiety
Gender
Meaning of pain
Coping style

Perception of pain- Pain perception is an essential component of the pain experience. Every individual perceive and interpret pain based on individual experience. Both physical stimuli and psychosocial factors have great influence on perception of pain. The pain perception may vary according to physiological factors such as inflammation or injury near pain receptors as well as person's threshold, endurance and past experiences.

Placebo effect- Placebos have been administered when health care providers doubted the clients were truly in pain. Placebos are pills that look like medications but that have no medicinal properties. When clients are given placebos, they are told that the pills contain pain medication. It has been reported that 30-70% of people receiving placebos report short-lived pain reduction or relief.

Sociocultural factors- Race, culture and ethnicity are critical factors in one's response to pain. These factors influence all sensory responses, including responses to pain. A person learns how to respond to pain and other experiences from family and culture. Pain responses tend to reflect the more of culture and ethnicity. Within this framework, people learn what is appropriate and acceptable for peer group and society.

Past experiences- Past experience with pain affects the way current pain is perceived. People who have had negative past experiences with pain can have difficulty in managing pain. The impact of past experiences, however, is not predictable. The person with a miserable experience in the past may perceive the next episode more intensely even though the medical conditions may be similar.

Age-Adults may not report pain for fear that it indicates weakness, failure, or loss of control. Pain perception may alter in older adults due to some damage to the CNS. Thus, transmission of perception may be slowed with aging, but intensity of the pain is not diminished. Age is considered as an important factor in deciding pain medications dosing. Metabolic changes in older adults affect their response to opioid analgesics. Drugs are metabolized and excreted more slowly in older people.

Anxiety-The degree of anxiety experienced by the client may also affect the response to pain. Anxiety intensifies pain perception. Anxiety is often related to the meaning of the pain.

Gender-Gender can be a significant factor in the pain response. It is believed that men report less pain than women regardless of ethnicity. This does not mean that men feel less pain only that they are assumed to show it less.

Meaning of pain- The meaning of a person's pain influences the person's responses to the pain. If the cause of pain is known, the person may be better able to interpret meaning and to deal with it. If the cause is unknown, more negative psychological factors (e.g., fear and anxiety) may be evoked, intensifying the degree of pain perceived. If the meaning of the experience is negative, then the pain may be perceived more intensely than pain perceived in situations with positive outcomes.

Coping style- The experience of pain can be lonely, when patient experiences pain in health care setting such as hospital the loneliness can be unbearable. Frequently patient feels a loss of central pain and an inability to control their environments or the outcome of events coping style thus inflacaces the ability to deal with pain.

Pain Assessment

P- recipitating/Alleviating Factors – What causes the pain? What aggravates it? Has medication or treatment worked in the past?
Q uality of Pain – Ask the patient to describe the pain using words like “sharp”, dull, stabbing, burning”
R adiation – Does pain exist in one location or radiate to other areas?
S everity – Have patient use a descriptive, numeric or visual scale to rate the severity of pain.
T iming – Is the pain constant or intermittent, when did it begin.

Assess for objective signs of pain-

Facial expressions – facial grimacing (a facial expression that usually suggests disgust or pain), frowning (facial expression in which the eyebrows are brought together, and the forehead is wrinkled), sad face.
Vocalizations - crying, moaning
Body movements – guarding , resistance to moving

Pain Assessment Tools • These are various tools that are designed to assess the level of pain. The most commonly used tools are-

Verbal Rating Scale-This pain scale is categorical pain scale. This scale gives the patient a simple way to rate their pain intensity using a verbal or visual descriptor of their pain. Some examples would be the words 'mild,' 'discomforting 'distressing,' 'horrible,' and 'excruciating.'

2. Numeric Rating Scale-The numeric scale is the most commonly used pain scale with adult patients, rating pain on a scale of 0-10. Many nurses ask for a verbal response to the question. Use of this scale with the visual analog can provide a more accurate response. This scale is appropriate with patients aged nine and older that are able to use numbers to rate their pain intensity.

3. Wong Baker’s Faces Pain Scale-

Can be used with young children (sometimes as young as 3 years of age)
Works well for many older children and adults as well as for those who speak a different language
Explain that each face represents a person who may have no pain, some pain, or as much pain as imaginable. Point to the appropriate face and say the appropriate description. e.g. “This face hurts just a little bit”

4. FLACC Scale- FLACC is the acronym for Face, Legs, Activity, Cry, and Consolability. This scale is based on observed behaviors, and is most commonly used with pediatric patients <3 years of age.

Pharmacological interventions

WHO Pain Management Ladder-

Pain scale reading	WHO Steps
1-3	STEP1
4-6	STEP2
7-10	STEP3

Pharmacological Interventions

Nonopioids- Used alone or in conjunction with opioids for mild to moderate pain –Eg; NSAIDS- paracetamol, aspirin.

Opioids –

Opioids are most powerful analgesics. Opioids are prescribed for moderate to severe pain when non- opioids are not effective in pain management.
Opioids are classified as mild opioids and strong opioids.
Common examples of mild opioids include tramadol, codeine, oxycodone, and hydrocodone.

Adjuvants –

Treatment that is given in addition to the primary (initial) treatment.
Adjuvant treatment is an addition designed to help reach the ultimate goal.
Adjuvant therapy for cancer usually refers to surgery followed by chemo- or radiotherapy to help decrease the risk of the cancer recurring (coming back).
Used for analgesic reasons and for sedation and reducing anxiety.

Eg-

Tri-cyclic antidepressants
Anti epileptics
Cortico steroids

Patient-Controlled Analgesia-

A drug delivery system called patient- controlled analgesia (PCA) is a safe method for pain management that many patients prefer.
It is a drug delivery system that allows patients to self-administer opioids (morphine and fentany) with minimal risk of overdose.
PCA infusion pumps are portable and computerized and contain a chamber for a syringe or bag that delivers a small, preset dose of opioid .
To receive a demand dose, the patient pushes a button attached to the PCA device.

Topical Analgesics

Topical analgesics are applied over the patients skin either in the form of topical ointments or transdermal patches.
The patches will be sticking to the skin and delivers a small amount of dosage continuosly.

Local Anesthesia

Local anesthesia is the local infiltration of an anesthetic medication to induce loss of sensation to a body part.
Health care providers often use local anesthesia during brief surgical procedures such as removal of a skin lesion or suturing a wound by applying local anesthetics topically on skin to anesthetize a body part.
The drugs produce temporary loss of sensation by inhibiting nerve conduction

Regional Anesthesia

Regional anesthesia is the injection of a local anesthetic to block a group of sensory nerve fibers.
Examples of regional anesthesia include epidural anesthesia and spinal anesthesia.

Non-Pharmacological Pain Management -

For many individuals, the use of non-pharmacologic methods enhances pain relief.
These nonpharmacologic strategies are often used in combination with medication

The methods are-

Heat applications- applicationsHelps decrease pain and muscle spasms. Apply heat to the area for 20 to 30 minutes every 2 hours for as many days as directed.
Cold applications-helps decrease swelling and pain. Ice may also help prevent tissue damage. Use an ice pack, or put crushed ice in a plastic bag. Cover it with a towel and place it on the area for 15 to 20 minutes every hour, or as directed.
Meditation
Distraction/Diversional-Diversional therapy is an individual specific technique for mild pain. It involves the redirection of patient's attention to something and away from the pain.
Imagery-May consist of combining slow, rhythmic breathing with a mental image of relaxation and comfort. The client is asked to practice guided imagery for about 5 minutes, three times a day
TENS application(Transcutaneous electrical nerve stimulation)-Transcutaneous electrical nerve stimulation (TENS). Uses a battery-operated unit with electrodes applied to the skin to produce a tingling, vibrating, or buzzing sensation in the area of pain. Decreases pain by stimulating the nonpain receptors in the same area as the fibers that transmit pain.
Music therapy-Music therapy can be used as an adjuvant with other modalities for the management of chronic pain. Music therapy helps to elevate the mood of the patient and serves as a distraction.
Massage-It is a common therapy for pain management. Many different massage techniques exist. For example, moving the hands or fingers over the skin slowly or briskly with long stokes or in circles (superficial massage) or applying firm skin pressure to maintain contact while massaging the underlying tissues (deep massage).
Yoga
Acupuncture-It is a technique of traditional Chinese medicine in which very thin needles are used to stimulate specific points around body. Needles are inserted to the body at designated points.
Acupressure-In acupressure, physical pressure is applied to acupuncture points with the aim of clearing blockages in these meridians. Pressure may be applied by hand, by elbow, or with various devices.
Herbal therapy- Garlic, Echinacea, Ginseng
Physical Exercise-It is a critical part of management plan for patients with musculoskeletal chronic pain. Exercise acts via many mechanisms to relieve pain.
Biofeedback- helps your body respond differently to the stress of being in pain. Healthcare providers may use a biofeedback machine to help know when your body is relaxed. You will learn what your breathing and heart rate are when you are relaxed. When you are in pain, you practice getting your breathing and heart rate to those levels.