Pain Definitions/Basics Flashcards
Acute Pain: other physiological sx
tachycardia, htn, diaphoresis (sweating), mydriasis
Chronic Pain: psych and nerves
social isolation, depression, anxiety
As pain signals are repetitively generated, neural pathways change and become hypersensitive
Malignant Pain
acute, chronic, or intermittent d/t cancer or chemo
Somatic Pain
skin, muscle, tendon, ligament, bone
sharp, stabbing, throbbing, aching
Visceral Pain
internal organs like liver, intestines, or stomach
Poorly localize, often referred pain far from problem
Neuropathic pain
Nerve damage - burning, numb, aching, electric shock
Neuro pain first line
TCAs, antiepileptics, serotonin-NE reuptake inhibitors
Nociception
Sensory nerve sends signal to spinal cord along ascending nerves. Secondary nerves in dorsal horn of spinal cord connects and relays to brain stem.
Descending Antinociception
ntms from descending fibers inhibit pain transmission
opioids resemble these ntms
Acute pain goal
Pain relief, short-acting meds
Malignant pain goal
Relieve patient’s pain without inducing disabling AEs
LA usually more appropriate, short acting for b/t
Chronic benign pain goal
Decrease intensity by at least 30%
Usually requires multimodal therapy-nerve blocks, rehab, PT, acupuncture, psychotherapy, meds
Non opioids and adjuvents involved
Adjuvent
primary indication is not pain (TCAs, antiepileptics, anesthetics,
Opioid MOA
Mimic endogenous opioid peptides in antinociceptive pathway - binding opioid receptors as AGONIST for analgesia. Opioid receptors are in CNS, pituitary, GI tract,
gray matter of brain, and dorsal horn of spinal cord.
Mu receptor
Binding = analgesia, sedation, euphoria, respiratory depression, physical dependence, constipation, etc
Delta receptor
Analgesia without many AEs (but no delta agonists exist)
Kappa receptor
Analgesia, respiratory depression
Also anxiety, strange thoughts, nightmares, hallucinations
Pure opioid agonist
Morphine (Methadone has NMDA too)
Primary activate mu, some kappa, most clinicaly useful
Mixed agonist-antagonist
Agonist at kappa - weak analgesia
Weak antagonist at mu - dysphoria, pshychomimetic effects
Pentazocine is prototype
Buprenorphine is partial agonist at mu and kappa
Opioid antagonists
block mu and kappa recptors, reverse respiratory and CNS effects
Naloxone, naltrexone
Tolerance
larger dose same response
sometimes mistaken for dz progression in ca pt
NO TOLERANCE: constipation and neuroendocrine effects
Physical dependence
withdrawal syndrome if stopped/quickly decreased
Addiction
use for nonmedical reasons, despite harm, decreased control/compulsive use, craving
