Untreated Pain Effects Quiz

Pain Physiology, Assessment & Treatment

• Veterinary Nursing 2 course material
• Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. The inability to communicate does not negate the possibility of experiencing pain.
• Pain is a complex phenomenon and a subjective experience.
• Pain elicits protective motor actions which leads to avoidance behaviours.

Nature of Pain

• Pain is a complex phenomenon described as an aversive sensory and emotional experience.
• Protective motor actions are triggered, resulting in avoidance behaviours.
• Species-specific behaviours may be altered.

Physiology of Pain

• Nociceptors are pain receptors in the nervous system.
• Acute pain: Severe, sudden onset overwhelming endogenous analgesic mechanisms.
• Chronic pain: prolonged and persistent pain, where the body becomes habituated to nervous system responses.

Nociception vs Pain

• Nociception is the process by which the nervous system detects potential or actual tissue injury.
• Pain is the subjective experience of tissue damage, accompanied by awareness of that damage. Nociception might be present without pain (e.g. during anesthesia), while pain will always have nociception component.

Nociception Pathway

• Transduction
• Transmission
• Modulation
• Perception

Pathologic Pain

• Pathologic pain is caused by damage or disease to the body, specifically tissue injury
• Pain can be acute or chronic in nature.

Classification of Pathologic Pain

• Categories may be based on the mechanism of pain (inflammatory, neuropathic, cancer, or idiopathic)
• Origin (visceral or somatic, superficial or deep)
• Severity (none, mild, moderate, or severe).

Types of Pain

• Somatic pain originates from damage to bone, joint, muscle, or skin; is usually localized.
• Visceral pain originates from internal organs and is poorly localized, from stretching or twisting of viscera, mesenteries, and ligaments.
• Neuropathic pain originates from injury to the peripheral or central nervous system.
• Inflammatory pain originates from tissue damage (e.g. trauma, ischemia, OA, laminitis).

Other Pathologic Pain Types

• Allodynia: Pain evoked by a stimulus that does not normally cause pain.
• Hyperalgesia: An increased or exaggerated response to a stimulus normally causing pain.
• Windup: Summation of painful stimulation in the spinal cord.

Pain Assessment Tools

• Simple descriptive scales
• Visual analogue scales
• Numerical rating scales
• CSU Canine Acute Pain Scale
• CSU Feline Acute Pain Scale
• Categorical numeric rating scales

Pain Assessment

• Observe behaviours like anxious expression, facial expressions, restlessness, panting
• Obtain heart rate, blood pressure, and respiration rate.
• Palpate for painful areas.

Pain Management

• Goals of analgesia are to reduce pain and prevent undesirable effects on patient physiology
• Use multimodal therapy, employing multiple drugs.
• Treat pain at one or multiple levels during an animal's hospitalization (transduction, transmission, modulation, and perception).

Consequence of Untreated Pain

• Sympathetic nervous system stimulation contributes to vasoconstriction and increased cardiac work, heart rate and oxygen consumption.
• Immune system suppression, delayed wound healing.
• Risk of increased anesthesia doses and increased anesthetic risk.
• Suffered increase patient pain.
• Pain has significant negative effects on both physical and physiological parameters of the body.

Analgesia Goal

• Reduce pain by interrupting nociception at one or multiple levels.

Multimodal Therapy

• Use of more than one drug to control pain, covering multiple receptors and mechanisms.

Types of Analgesics Targeted at Specific Steps in Nociception Pathway

• Inhibit perception: anesthetics, opioids, benzodiazepines, phenothiazines.
• Inhibit transmission: local anesthetics, opioids, alpha-agonists.
• Inhibit modulation: local anesthetics, opioids, tricyclin antidepressants, cholinesterase inhibitors, NMDA antagonists, NSAIDs, and anticonvulsants.
• Inhibit transduction: local anesthetics, opioids, NSAIDs, corticosteroids.

Examples of Multimodal Anagesia

• Acetaminophen & codeine for moderate-severe pain in dogs.
• Fentanyl & meloxicam for pain relief in cats.
• Morphine, Lidocaine, & Ketamine (MLK) for moderate-severe pain in dogs.

Analgesia Timing

• Analgesia is important at every stage of hospitalisation (pre-anesthesia, surgical period, immediately postoperative, remainder of stay at home).

Criteria for Drug Choice

• Severity and type of pain.
• Patient's general condition.
• Route of delivery.

Signs of Animal Pain

• Vary depending on species, age, breed, and temperament.
• Young patients less tolerant.
• Large breeds of dogs more stoic than small or toy breeds.
• Cats tend to hide, whereas dogs seek owner comfort, with the herd animals separating themselves.
• Pain response can vary based on nature, duration, and severity of pain, and presence of humans.
• Changes in behaviour, posture, facial expressions, and attitude are common.
• Signs to look for: vocalization (whimpers, growls, etc.), reduced appetite, changes in posture (guarding behaviour, avoiding movement), changes in facial expression/attitude/appearance, difficulty sleeping, depression, changes in gait or motility, reluctance to move, constant shifting of position, decreased grooming.

Signs of Pain (in general)

• Decreased appetite, decreased sleeping time, changes in posture, changes in gait (level of activity), and reluctance to lie down.
• Decreased grooming, poor body condition, significant reductions in activity or motility.
• Vocalization signs (whining, growling etc.) emergence delirium, immediate postoperative vocalization, changes in facial expressions, and attitude, (crouching, posture alteration, head tilt)
• Specific examples in different animal types are also mentioned (canine, feline, equine) behaviours.

Pain in Animals Under Anesthesia

• Anesthetized animals can process nociception but aren't consciously aware.
• Signs of pain under general anesthesia include increased heart rate and respiration rate, increased blood pressure, difficulty maintaining plane of anesthesia, trembling, changes in normal behaviour (or lack thereof), changes in normal posture/movement.

Things to consider

• When was the last analgesia?
• Was it adequate?
• Age of the animal and comorbidities.
• Severity of pain
• Surgery duration

Pain vs Anxiety

• Pain can be difficult to distinguish from anxiety, as physiological changes similar to anxiety can occur during pain. Observing patient behaviours can assist to distinguish, with pain generally being more acutely reflected, whereas anxiety can be more chronic in nature.

Consequences of Untreated Pain

• Sympathetic stimulation (vasoconstriction, increased cardiac work/heart rate, increased oxygen consumption/hypoxia)
• Immune/inflammation system issues /delayed wound healing or impaired healing)
• Increased anesthetic risk / increased anesthetic doses required; greater adverse effects of anesthesia/recovery etc.)
• Patient suffering

Stress-response Consequences of Untreated Pain

• Cardiovascular effects (tachycardia, hypertension, arrhythmias)
• Respiratory effects (atelectasis, hyperventilation/hypoventilation, hypoxia)
• Gastrointestinal effects (delayed gastric emptying, nausea, ileus)
• Renal effects (oliguria and urinary retention)
• Hematological effects (hypercoagulability, thrombosis risk)
• Psychological effects (anxiety, fear, fatigue, suffering)

Recall: References - CRI

• Reference materials: McCurnin's Clinical Textbook & small animal ECC textbook.
• Specific chapters and pages are cited to indicate the location of references

Calculating Constant Rate Infusion

• Detailed steps for calculating CRI dosages, covering different units (mg/kg/hr vs mcg/kg/min) with specific examples.

Pain Assessment, Different Species

• Detailed descriptions of pain assessment techniques for equine, feline, canine, and ruminants.
• Common behaviours to look out for in each animal type (eg lameness, changes to posture, vocalization, hiding, aggression, stress response)

Non-Pharmacological Interventions

• Differentiating pain from other stress-related behaviours.
• Assessing physical and emotional needs
• Provide physical comfort or distraction methods to alleviate perceived stress/anxiety.
• Reassessing patient comfort after addressing emotional and physical pain needs

Analgesic Options: Non-Pharmacological

• General nursing care, including cleanliness and padding.
• Acupuncture
• Laser analgesics
• Physical therapies (massage), ice/cold therapy

Summary of AAHA Pain Management Standards

• Pain assessment is essential for every patient, especially preemptively.
• Recording pain assessments in medical records.
• Employing preemptive pain relief measures.
• Appropriate pain management for surgical procedures and chronic pain.
• Using written protocols and teaching client to recognize pain.

Remember Pain Management

• Each patient is unique
• Pain can be well-hidden, with many factors contributing to this including stress and anxiety
• The procedure itself can profoundly influence perception of pain & therefore requirements for pain management.

Monitoring Drug Effects

• Careful monitoring of cardiovascular & mental health in patients is critical when assessing effects of pain relief medicines.
• Assess for detrimental side effects, or complications and/or further stress factors, and treat these adverse consequences as needed.

Dysphoria vs Anxiety

• Dysphoria: A state of uncontrolled unpleasant thoughts and feelings (often induced by drugs).
• Anxiety: Feeling of worry, nervousness, or unease.
• Distinction is important because treatments differ

Overview of Analgesic Categories

• Opioids, NSAIDs, locals, alpha-2 agonists, NMDA antagonists, and gabapentin are all presented.

Analgesic: Opioids

• Mainstay for perioperative pain, highly effective, minimal side-effects, and generally inexpensive.
• Act on opioid receptors (mu, kappa, delta) within various sections of the body (transduction, modulation, and perception).
• Different forms of opioid action are provided (eg. mu agonists).

Analgesic: NSAIDS

• Act by blocking COX-1 and COX-2 enzymes.
• Anti-inflammatory and antipyretic.

Analgesic: Local Anesthetics

• Block Na-gated channels, preventing action potential propagation in nerve fibers
• Extremely effective but generally short-acting.

Analgesic: Topical Anesthesia

• Applied to surface skin or mucosa to reduce pain.
• Effective for minor procedures such as wound surgery, venipuncture, arterial punctures, and nasal cannulation.

Analgesic: Alpha-2 Agonists

• Decrease NE release peripherally and centrally.
• Provide potent analgesia in horses, less effective in other species.

Analgesic: NMDA Antagonists

• Block glutamate receptors, helping reduce central sensitization
• E.g., Ketamine (dissociative agent).

Analgesic: Gabapentin

• Analgesic adjunct.
• Used primarily for neuropathic and chronic pain.
• Helps to prevent/decrease central sensitization (preemptively or before surgery).
• May have mild sedative properties, especially in cats.