Anethesia/Analgesia Flashcards
(61 cards)
What are the characteristics of Silent/sleeping nociceptors?
present in both A- delta and C- fibers
high-threshold activated by tissue damage
important in peripheral sensitization
What is the most important tract in transmitting of nociceptive information?
spinothalmic tract
What cortical areas are activated during perception?
Reticular system: autonomic & motor response to do something
Somatosensory cortex: ids intensity, type & location & relates to past experience to memory
Limbic system: emotional/behavioral response to pain
What is the noradrenergic mechanisms?
happens in the locus coeruleus to the dorsal horn
stimulates adrenergic receptors
decrease in the release of substance P
How does the noradrenergic mechanism decrease the release of substance P?
Hyperpolarizing 2nd order neurons
depolarizing GABAergic neurons to inhibit pain transmission
What occurs in the Serotonergic pathway in the descending pathway?
Excitatory effects
release enkephalins which inhibit the release of substance P and hyperpolarizing 2nd order neurons
The inhibition of nociception is due to what?
The hyperpolarization of 2nd order neuron
What are the steps in the opioid system?
1) directly inhibit stimulus
2) Inhibit calcium influx prevents action potential which inhibits substance P
3) Promote potassium efflux membrane hyperpolarization which inhibits pain transmission
4) disinhibit descending modulatory pain pathways
Explain the mechanism behind primary hyperalgesia
Substance P will excite sensory and sympathetic fibers which allows for vasation of plasma proteins. this recruits inflammatory cells. A- delta and C- fiber activation activates silent nociceptors
Explain the mechanism behind secondary hyperalgesia (Wind-up).
NMDA receptor activation
influx of Ca
Increase sensitivity to glutamate
What is allodynia?
a phenomenon in which an area close to the site of tissue injury is painful if stimulated w/ a normal non-noxious stimulus
What are the effects of pain on the immune system?
Increased cortisol levels leads to impaired wound healing & decreased immune system
Increased ADH, catecholamines, renin, etc
Decreased in insulin
What are the effects of pain on the neuroendocrine system?
Hyperglycemia
impaired metabolism results in increase protein catabolism, lipolysis & cochexia
What are the effects of pain on the GI system?
Shunting of blood
Decrease motility
Decrease mucosal integrity
What are the effects of pain on the cardiovascular system?
Fluid retention
increased BP
decreased renal perfusion
Increased HR, SV, CO
What are the effects of pain on the respiratory system?
Ventilation perfusion mismatch
arterial hypoxemia
hypercarbia
What are the effects of pain on the coagulation system?
Increased platelet adhesiveness
decrease fibrinolysis
hypercoagulation
What is the cut off on the pan face scale for cats to get rescue analgesia?
> or = to 4/10
What is the difference between pain and dysphoria?
Dysphoria is difficult to distract/calm
opioids do not help
not identifiable source of pain
fixed dilated pupils unresponsive
What is acute (adaptive) pain?
an abrupt & brief event usually related to trauma, surgery or infection & medical diseases
What is chronic (maladaptive) pain?
Pain persists beyond a responsible time for the course of an acute disease or an injury to heal
What is somatic pain?
Originates from damage to somatic tissue (bones, joints, tissue)
sharp
localized
What is visceral pain?
arises from visceral injury
not well localized
associated with nausea & vomiting
What is neuropathic pain?
direct damage to peripheral nerves/spinal cord
described as burning/shooting pain
difficult to treat
