Understanding Pain Mechanisms and Management

Pain Management

Pain Definitions

• Pain, as defined by the International Association for the Study of Pain (IASP), is an unpleasant sensory and emotional experience related to actual or potential tissue damage.
• Pain is what the experiencing person says it is.
• Pain threshold refers to the least stimulus intensity at which a subject perceives pain.
• Pain is the most common reason that clients seek medical advice.
• Pain is a protective mechanism that warns to prevent further injury.

Types of Pain: Location

• Pain can be described in terms of location, duration, intensity, and etiology.
• Referred pain appears to arise in different areas from the source, with cardiac pain potentially felt in the shoulder or left arm, with or without chest pain.
• Visceral pain, originating from organs or hollow viscera, is often perceived in an area remote from the organ causing the pain.

Types of Pain: Duration

• Acute pain has a sudden or slow onset, regardless of its intensity.
• Chronic pain, also known as persistent pain, lasts 3 months or longer, recurs regularly and interferes with functioning.
• Acute and chronic pain produce different physiological and behavioral responses.
• Cancer pain can be a direct effect of the disease and its treatment or be unrelated
• Other diagnoses over time, like HIV/AIDS or burn pain, have been included in the “malignant pain" category.

Comparison of Acute and Chronic Pain

• Acute pain is characterized by mild to severe intensity, sympathetic nervous system responses, increased pulse and respiratory rates, elevated blood pressure, diaphoresis, and dilated pupils.
• Acute pain resolves with tissue healing.
• Acute pain clients may be restless and anxious, report pain, and exhibit pain behaviors, such as crying, rubbing the affected area, or holding the affected area.
• Chronic pain is characterized by mild to severe intensity with parasympathetic nervous system responses, and vital signs within normal ranges
• Chronic pain has dry, warm skin, along with normal or dilated pupils, and it continues beyond healing.
• Those with chronic pain may be depressed and withdrawn and not mention their pain unless asked, and have absent pain behavior

Types of Pain: Intensity

• Most practitioners classify pain intensity by a standard scale from 0 (no pain) to 10 (worst possible pain).
• Pain in the 1 to 3 range is deemed mild, 4 to 6 is moderate, and 7 to 10 is severe, which is associated with the worst outcome.

Defense and Veterans Pain Rating Scale

Types of Pain: Etiology

• Nociceptive pain results when an intact, properly functioning nervous system signals damaged tissues that require proper care.
• The pain felt after a cut or broken bone alerts the person to avoid further damage until it is properly healed.
• Somatic pain originates in the skin, muscles, bone, or connective tissue, with examples including the sharp sensation from a paper cut or the ache of a sprained ankle.
• Visceral pain comes from activation of pain receptors in the organ or hollow viscera and can be characterized by cramping, throbbing, pressing, or aching qualities and is often associated with feeling sick
• Visceral pain examples include labor pain, angina pectoris, or irritable bowel.
• Neuropathic pain is associated with damaged or malfunctioning nerves due to illness, injury, or undetermined reasons.
• Neuropathic pain is typically chronic, described as burning or "electric-shock,"and can be difficult to treat.
• Subtypes of neuropathic pain are based on the nervous system believed to be damaged

Neuropathic Pain: Peripheral vs Central

• Peripheral neuropathic pain (phantom limb pain) follows damage or sensitization of peripheral nerves.
• Central neuropathic pain (spinal cord injury pain, or multiple sclerosis pain) results from malfunctioning nerves in the central nervous system (CNS).

Additional Terms Used by Patients to Describe Pain

• Sharp pain is intense and sticking in nature
• Dull pain is not as intense or acute as sharp pain and is more annoying than painful.
• Diffuse pain covers a large area and the patient cannot identify the location without moving their entire hand over the abdomen.
• Shifting pain moves from one area to another.
• Other terms used for the pain quality stinging, sore, pinching, cramping, gnawing, cutting, throbbing, or viselike pressure.

Assessing Severity

• Interpreting pain depends on behavioral and physiologic signs.
• On a scale of 1 to 10, slight pain is described between 1 and 3, , moderate pain between 4 and 7, and severe pain between 8 and 10.
• Continuous pain doesn't stop.
• Intermittent pain stops and starts again.
• Brief or transient pain passes quickly.

Concepts Associated with Pain

• Pain threshold is the least amount of stimuli needed for a person to label a sensation as pain.
• Pain tolerance is the maximum amount of painful stimuli a person is willing to withstand without seeking relief, varying considerably among individuals and circumstances.
• Dysesthesia is an unpleasant abnormal sensation either spontaneous or evoked.
• Hyperalgesia is an increased sensation of pain in response to a normally painful stimulus.

Physiology of Pain

• Four physiological processes are involved in nociception: transduction, transmission, perception, and modulation.
• The peripheral nervous system has specialized primary sensory neurons detecting mechanical, thermal, or chemical conditions associated with potential tissue damage.
• When these nociceptors are activated, signals are transduced and transmitted to the spine.
• Transduction: Harmful stimuli triggers the release of biochemical mediators, such as prostaglandins, bradykinin, serotonin, and histamine, sensitizing nociceptors.
• Transmission: This process involves the peripheral nerve fiber to the spinal cord, then spinal cord to the brain through an ascending pathway and information to the brain where pain perception occurs.
• Perception, is when the client becomes conscious of the pain.
• Pain perception is the sum of complex activities in the CNS, which may shape the character and intensity of pain perceived and give meaning to the pain
• Modulation, the "descending system”, is the final process. -Neuron in the brain sends signals back to the dorsal horn of the spinal cord. -Descending fibers release substances (endogenous opioids, serotonin, and norepinephrine), which can inhibit or reduce ascending painful impulses in the dorsal horn.

Factors Affecting Pain Perception

• Culture, age, meaning of pain, attention, anxiety and sex play roles in affecting pain perception.

Nursing Process: Assessment

• Use the acronym PQRSTAAA in the nursing assessment -Position: Where is the pain -Quality: What does the pain feel like [sharp, dull, burning] -Radiation: Does the pain radiate -Severity: Rate the pain on a scale between 0-10 -Timing: When did the pain start? Is it continuous -Aggravating Factors: What makes it worse -Alleviating Factors: What makes it better -Associated symptoms: nausea or pins and needles

Pain Scales

• Simple Descriptive Pain Intensity Scale
• 0-10 Numeric Pain Intensity Scale
• Visual Analog Scale (VAS)
• Pain Rating Scale for children with faces

Nursing Process: NANDA Diagnoses

• The North American Nursing Diagnosis Association (NANDA) includes Acute & Chronic Pain diagnostic labels for discomfort.
• Nursing statements should include location and related factors -Ineffective Airway Clearance related to weak cough secondary to postoperative incisional abdominal pain -Hopelessness related to feelings of continual pain -Anxiety related to past experiences of poor control of pain and anticipation of Pain

Pharmacological Treatment of Pain

• There are 3 types of pharmacological treatments:

1. Non-Opioids,
2. Opioids,
3. Adjuvants

A- Non-Opioids

• Paracetamol (Panadol): -PO, IV, Act centrally & peripherally -Max. Daily Dose: 3gm of OTC meds, 4 gm IV.
• Non-steroidal Anti-inflammatory Drugs (NSAIDs) -Ketorolac (Toradol)- inj -Ibuprofen (Advil, Neurofen, Brufen) -Diclofenac Na/K (Voltaren, Olfen, Cataflam) -Mefanemic acid (Ponstan) -Naproxen (Naprosyn) -Celebrex (Celecoxib) -Etoricoxib (Arocoxia) -Meloxicam (Mobic)

NSAIDs: Ketorolac

• Postoperatively for max 5 days
• Reduce the amount of opioid requiremen
• Reduce side effects

Cox-2 Inhibitors

• Effective anti-inflammatory in cases of arthritis
• Carry a cardiovascular risk warning
• Less GI S.E's

NSAIDs: Side Effects

• Prolong bleeding time
• Gastric erosions/ ulceration/ perfusion
• Affect Kidney Function: -Water / electrolyte balance -Interfere with diuretics/ antihypertensive -Renal injury / nephrotic syndrome

B- Opioids

• Morphine
• Meperidine (Pethidine)
• Fentanyl
• Codeine (Solpadeine: codeine 8mg/Aceta./caffeine)
• Hydromorphone
• Tramadol (Tramal)

Opioids/Narcotic Analgesics

• Morphine: -The gold standard opiate. -Bolus: 2-5 mg slowly over 5min (Q 1-3 hrs). -CI: 1mg/hr titrated to the desired analgesic effect. -IM; 5-10 mg (Q3-4 hrs). -SC: not recommended in repeated dose.
• Meperidine: -Used in acute pain only, alternative for morphine intolerance. -Limited use because of toxic metabolite, sedative, and emetic effect.
• Fentanyl: -100 times more potent, rapid onset of action gives better control -Administered: Bolus, CI, oral, patches.
• Tramadol: -Acts on opioid & non-opioid receptors (moderate pain) -Show Poor analgesic effect as compared to morphine.

Opioids: Side Effects

• Nausea
• Vomiting
• Constipation
• Pruritis
• Irritable Movement
• Psychomimetic effects - Sedation
• Broncho-constriction
• Respiratory Depression

Opioids and Respiratory Depression

• If respiratory depression/sedation develops, be familiar with administration of Naloxone, it will reverse the effect
• Naloxone is diluted (0.4 mg in 10 mL NS) every 1-2 min to improve respiratory status until patient starts to arouse.

C- Adjuvants

• Agents are used to inducean analgesic effect indirectly - Local Anesthetics - Antidepressants - Anticonvulsants - Corticosteroids - Muscle Relaxants - Anti-histamines

Choice of Drugs to Treat Acute/Chronic Pain should consider

• Severity of the pain
• Route of administration
• Patient Information
• Pharmacokinetic of the drug
• Patient preference

Non-Pharmacological Techniques

1. Psychological Interventions - Provision of information (Procedural information summarizes what will happen during treatment) - Stress and Tension Reduction (Relaxation training usually involves teaching a patient ways of de-stressing via various methods and techniques.) - Hypnosis (shares relaxation qualities and has history of curing acute pain) - Attention Techniques (Distraction from pain includes music, scenes and smells)
2. Cognitive-Behavioral Interventions (Pain coping strategies w/in a cognitive-behavioral intervention include learning to think positively)
3. Transcutaneous Electrical Nerve Stimulation (TENS)

• Systematic reviews show it as ineffective for post-op pain relief

4. Acupuncture

• Acupressure includes physical pressure to acupuncture points

5. Other Physical Therapies -Manual and Massage Therapy -Heat and Cold(Compresses)

Surgical Interventions

    -Cordotomy: surgical procedure meant to relieve the pain by cutting the nerves of the spinal cord.
    -Rhizotomy: surgical procedure meant to sever nerve routes in the spinal cord, effectively relieving chronic back pain and muscle spasms.

Explore the complexities of pain, from IASP definitions to classifications of acute and chronic pain. Learn about pain intensity assessment, pain related to HIV/AIDS, and the physiological purpose of pain. Understand referred pain, cancer treatment-related pain, and the processes of nociception and pain modulation.