Pharmacology of Analgesia I Flashcards
Analgesia definition
The absence of pain sensation
Distress definition
Physical or emotional display of physical or mental strain
Hyperesthesia definition
Increased sensitivity to non-noxious stimuli
Nociceptor definition
Receptor that translates tissue damage to pain perception
Basic structure of afferent pathway is…
A 3-neuron chain
- Peripheral fiber
- Spinal tract
- Brain
Transduction definition (nociception)
Translation of noxious stimuli into electrical activity at peripheral nociceptor
Transmission definition (nociception)
Movement of the nerve impulse through nervous system
Modulation definition (nociception)
Change of pain perception by the efferent analgesic system
The order of nociception:
Surgical pain –> ____–>____–>___–>___
Surgical pain –> Transduction –> Transmission –> Modulation –> Brain
Name three consequences of pain (7)
- Decreased quality of life
- Increased risk of infection
- Delayed wound healing
- Reduced food & water intake
- Decreased sleep (quantity, quality)
- Behavior changes
- Mobility changes
Name three ways to recognize pain (7)
- Increased blood pressure
- Increased HR
- Increased respiratory rate
- Stress leukogram (CBC)
- Vocalization
- Hiding
- Posture changes
Step 1 of pain scoring: Non-interactive behavior scoring
Name grades 0-4
Grade 0
- No pain or hint of discomfort
Grade 1
- Seems in comfortable position in room
Grade 2
- Shifting positions but quiet
Grade 3
- Restless, anxious, & unsettled
Grade 4
- Vocalizing/becomes stiff/guards with body parts or thrashing
Step 2 of pain scoring: Interactive behavior
Name grades 0-4
Grade 0
- Shows greeting behavior/wagging tail/approachable
Grade 1
- Curious/approaches but hesitates with movement
Grade 2
- Hesitates to approach/restricted interaction/not moving comfortably
Grade 3
- Wary/slow movement usually away from person/guarding
Grade 4
- Unaware of surroundings/not moving/vocalizing
Step 3: Palpation/touching patient
Name grades 0-4
Grade 0
- Can palpate or touch; no negative response
Grade 1
- Can palpate or touch; no resistance/may look or sniff area
Grade 2
- May slightly object to gentle palpation/may lick lips or affected area/holds body still
Grade 3
- Withdraws immediately/mild vocalization/tense or guarding/stiffness
Grade 4
- Tries to escape/bites/grinds teeth or grimaces/ears are back/hides affected area/loud vocalization
Strategy for pain management
Preemptive analgesia (3)
- Begin analgesic techniques before the patient is exposed to noxious stimuli
- Minimizes duration & intensity of animal discomfort
- Minimizes the amount of drug needed to control pain; decreases anesthesia drugs
“Wind up” definition
- Repeated pain impulses to the brain lead to increased sensitivity to pain if they occur over time.
- So, if pain stimulation is occurring during surgery, there will be a higher sensitivity to pain when the animal regains consciousness.
How to prevent “wind up”
Give analgesia prior to surgery!
Strategies for pain management
Multimodal analgesia (2)
- Simultaneous use of two or more analgesic drug classes or techniques
- NSAID or opiate
- Local anesthetic & systemic anesthetic - Interrupts transduction of pain at different sites along pain pathway
Mode of delivery of a drug can make a major difference in the ___ of therapy. It can also make a major difference in time of ___ of action.
- Effectiveness
- Onset
Modes of drug delivery (5)
- Oral (PO)
- SQ
- IV
- Constant rate infusion
- Transdermal
How to use a transdermal patch (7)
- Shave patient without causing abrasion
- Clean skin with water only
- When dry, apply patch to skin & hold with warm hand 60 seconds
- Apply bandage to maintain skin contact
- Label bandage with date, time, dose, & initials
- Never cut the patch! If Pt only needs half, leave paper backing on half & sticky half on Pt
- 8-24hr ramp up time
Constant rate infusion (CRI) is an ___ technique used with many different types of drugs.
The dosage is given as a fixed amount per ___. The dosage is delivered directly into the ___ fluids, if the fluids are given at a fixed rate.
The dosage can be delivered in a Buretrol at a rate ___ of fluid support.
Types of drugs used: (5)
- IV
- Time
- IV
- Independent
Types:
- Electrolytes
- Anti-nausea
- Anti-arrhythmia
- Insulin
- Analgesia (ie opioids)
Modes of delivery for analgesia (2)
Ways of doing so (6)
Local or regional
1. Subcutaneous (infiltrative)
2. Topical
3. Epidural
4. Nerve blocks
5. Intra-articular
6. Pleural
Infiltrative block
How to administer (2)
AKA “local” block
1. Shave & surgical prep of region
2. 22G needle inserted & anesthetic injected at multiple SQ sites to cover “inverted pyramid”
- Lidocaine
- Bupivacaine
Intra-articular analgesia
How to administer (2)
- Shave and surgical scrub skin over joint
- Sterile needle is guided into the joint
- Lidocaine
- Bupivacaine
- Morphine
Epidural
How to administer (6)
- The L7 region is shaved, and surgical prep is performed
- Spinal needle is inserted into the epidural space
- Anesthetic agent is injected into the CSF fluid
- Aseptic technique is mandatory!
- Significant skill is required for this procedure in small animals
- Commonly done for large animal surgeries
