Pain, Analgesia and Anesthesia

Noiception v.s. Pain

Noiception = signal

Pain = perception

• perception is based on client’s report

Where do NSAIDS and corticosteroids work

Transduction

Where do local anesthetics work

transmission

Where do opioids work

perception

Where do antidepressants, anticonvulsants and opioids work?

modulation

Opioids

Used for acute pain

MOA:

• work on mu receptors in brain

ADR:

• respiratory depression

naloxone

reverses opioid effects

Morphine

Class: Opioid Agonist (Narcotic Analgesic)

MOA:

• Binds to opioid/ mu receptors to alter pain perception

ADR:

• respiratory depression

• constipation

*Black box warning: Schedule II Drug

*extended release for opioid-tolerant clients only

Fentanyl

Class: Opioid Agonist (IV Anesthetic)

MOA:

• Binds to mu opioid receptors for potent, rapid, pain relief

ADR:

• Respiratory Depression

*Most powerful Opioid

*50-100 times more potent than morphine

Tramadol

Class: Synthetic Opioid Analgesic

MOA:

• binds to weak mu receptors, inhibits serotonin uptake, inhibits pain transmission impulse

ADR:

• dizziness

• serotonin syndrome

*Do Not use w/ history of seizures

*watch for seizures

Levels of CNS Depression

Sedation - calm, awake

Moderate Sedation - drowsy, arousable

Deep Sedation - difficult to arouse

General Anesthesia - unconscious

General Anesthesia

MOA:

• works on GABA receptors

Result: unconsciousness

Risks:

• respiratory depression

Isoflurane

MOA:

• GADA agonist, NMDA antagonist

ADR:

• malignant hyperthermia

• severe hepatic disease

Nitrous Oxide

MOA:

• NMDA agonist, weak anesthesia

ADR:

• diffusion hypoxia (if not administered with O2)

*must be administered w oxygen

*check O2 state

Propofol

MOA:

• GABA agonist

ADR:

• propofol infusion syndrome

*caution with egg and soy allergy

Midazolam

Sedative

MOA:

• enhances GABA

ADR:

• respiratory distress

*reversal agent: flumazenil

Neuromuscular Blockers Characteristics

• paralysis only (no sedation, anesthesia, amnesia)

• ALWAYS give with sedation or analgesia first

• have airway + reversal agents ready

• need breathing tube

Succinylcholine

Neuromuscular Blocker

MOA:

• nicotinic receptor agonist

ADR:

• hyperkalemia

• malignant hyperthermia

*very fast onset, little half-life

Rocuronium

Neuromuscular Blocker

MOA:

• Nicotinic Receptor agonist

ADR:

• respiratory paralysis (expected)

• hypotension

Malignant Hyperthermia

A severe fever based on a gene

• mutation in RYRI receptor

*get family history before anesthesia

Dantrolene

MH Antidote - given to stop malignant hyperthermia

MOA:

• blocks calcium release

Lidocaine

Local Anesthetic

MOA:

• blocks sodium channels

ADR:

• CNS + cardiac effects

*watch for early toxicity