Acute Postop Pain

Question 1

Pain

Answer 1

5th vital sign
Unpleasant sensory & emotional experience associated w/ actual or potential tissue damage
Consistent w/ tissue injury degree

Question 2

Acute Pain

Answer 2

Short duration
<6 weeks
Known cause
Temporary & located in area trauma or damage
Resolves spontaneously w/ healing

Question 3

Chronic Pain

Answer 3

Persists beyond normal recovery duration from acute injury or disease
Cause not always identifiable
Affects patient self-image & well-being

Question 4

Neuropathic Pain

Answer 4

Abnormal or unfamiliar pain
CNS or PNS dysfunction - injury or acquired abnormalities
Central pain d/t injury to brain or spinal cord (phantom pain)
Peripheral originates in nerve root, plexus, or nerve

Question 5

Idiopathic Pain

Answer 5

Pain not attributable to identifiable physical or psychological cause
Perception - excessive pain

Question 6

Psychogenic Pain

Answer 6

Sustained via psychological factors

Effective & behavioral disturbances

Question 7

Nociceptive Pain

Answer 7

Appropriate response to identifiable tissue damage

Question 8

Nociception

Answer 8

Noxious stimuli detection, transduction, & transmission

Question 9

Transduction

Answer 9

Stimuli translated into electrical energy at the site

Question 10

Transmission

Answer 10

Impulse propagation via the nervous system

Question 11

Modulation

Answer 11

Stimuli alteration

Amplified or attenuation

Question 12

Perception

Answer 12

Based on patient’s psychological framework

Question 13

Somatic

Answer 13

Superficial arises from skin, subcutaneous tissues, & mucous membranes

• Sharp, pricking, throbbing, or burning
• Well localized

Deep arises from muscles, tendons, joints, or bones
- Dull, aching & less localized

Question 14

Visceral

Answer 14

Internal organ disease process or abnormal function

Localized or referred

Question 15

Allodynia

Answer 15

Ordinarily non-noxious stimulus perceived as pain

Question 16

Analgesia

Answer 16

Absence pain perception

Question 17

Anesthesia

Answer 17

Absence all sensation

Question 18

Hyperalgesia

Answer 18

Exaggerated response to noxious stimuli

Question 19

Neuralgia

Answer 19

Pain in nerve distribution

Question 20

Paresthesia

Answer 20

Abnormal sensation perceived w/o stimulus

Question 21

Radiculopathy

Answer 21

Functional abnormality 1+ nerve roots

Question 22

Class A α

Answer 22

Peripheral afferent nerve fibers 
Large myelinated fibers
Low activation threshold
Diameter 1-20μm 
ALPHA
Conduction impulse 60-120m/s
Transmits motor & proprioceptive impulses

Question 23

Class A β

Answer 23

Peripheral afferent nerve fibers 
Large myelinated fibers
Low activation threshold
Diameter 1-20μm 
BETA
Conduction impulse 60-120m/s
Cutaneous touch & pressure

Question 24

Class A δ

Answer 24

Peripheral afferent nerve fibers 
Large myelinated fibers
Low activation threshold
Diameter 1-20μm 
DELTA
Conduction impulse 5-25m/s
Mediates pain sensation
- Transmits fast or first pain
- Sharp, stinging, pricking
Glutamate binds to NMDA receptors

Question 25

Class A γ

Answer 25

``` Peripheral afferent nerve fibers Large myelinated fibers Low activation threshold Diameter 1-20μm GAMMA Conduction impulse 5-25m/s Cutaneous touch & pressure ```

Question 26

Class B

Answer 26

Peripheral afferent nerve fibers Medium-sized myelinated fibers Higher threshold (lower excitability) than Class A & lower threshold than Class C fibers Diameter <3μm Conduction speed 3-14m/s Post-ganglionic sympathetic & visceral afferents

Question 27

Class C

Answer 27

``` Peripheral afferent nerve fibers Un-myelinated or thin myelination Diameter 0.4-1.2μm Conduction speed 0.5-2m/s Pre-ganglionic autonomic & pain fibers - Transmits slow or second pain - Burning, persistent, aching, throbbing pain Substance P binds to NK-1 receptors ```

Question 28

Pain Modulation

Answer 28

Descending dorsolateral spinal tract

Question 29

Supraspinal Analgesia

Answer 29

Mu-1 receptors Limbic system, hypothalamus, & thalamus IV opioids

Question 30

Spinal Analgesia

Answer 30

Mu-2 receptors Periventricular/periaqueductal grey IV & neuraxial opioids

Question 31

Surgical Stress Response

Answer 31

CV ↑HR/CO ↑BP ↑SVR (angiotensin II) ↑MVO2 Resp ↑O2 consumption ↑CO2 production ↑minute ventilation ↑WOB ↓chest expansion d/t pain → atelectasis, intra-pulmonary shunting, hypoxemia, & hypoventilation Endocrine ↑glucagon ↓insulin ↑epinephrine → vasoconstriction ↑myocardial contractility ↑cortisol & catecholamines → RAAS activation (Na+ & H2O retention) GI ↑sphincter tone ↓VSMC tone → ileus or PONV ↑gastric acid production → stress ulcers Immune - leukocytosis w/ lymphopenia ↓RAS → infection risk Heme ↑platelet adhesiveness ↓fibrinolysis → hypercoagulable state

Question 32

Opioid-Induced Hyperalgesia

Answer 32

Diminished pain threshold & enhanced pain sensitivity

Question 33

Multi-Modal Approach

Answer 33

``` NSAIDs Ketamine Methadone Anticonvulsants Dexmedetomidine Clonidine Magnesium Glucocorticoids Local anesthetics Regional anesthesia ```

Question 34

NSAIDs

Answer 34

Effective to treat mild to moderate pain Adverse effects include GI bleeding, acute renal failure, & hepatotoxicity Caution in elderly patients d/t ↑risk renal impairment

Question 35

Ketamine

Answer 35

NMDA antagonist Bolus 0.5mg/kg Infusion 4mcg/kg/min

Question 36

Methadone

Answer 36

D-isomer NMDA antagonist | 0.2mg/kg

Question 37

Anticonvulsants

Answer 37

Pregabalin & Gabapentin Manage spontaneously firing sensory neurons associated w/ neuropathic pain - Attenuate neuronal sensitization response

Question 38

α2 Agonists

Answer 38

Dexmedetomidine Clonidine RISK BRADYCARDIA & HYPOTENSION

Question 39

Acetaminophen

Answer 39

15mg/kg

Question 40

Glucocorticoids

Answer 40

Anti-inflammatory + PONV

Question 41

Regional Anesthesia

Answer 41

``` Peripheral nerve blocks - Lumbar plexus - Interscalene Central neuraxial blocks - Spinal - Epidural ```

Question 42

Neuraxial Opioid Side Effects

Answer 42

``` Itching (most common) Nausea Urinary retention Respiratory depression (early & late) Sedation CNS excitation Neonatal morbidity ```