IV anesthetics

Question 1

Types of anesthesia

Answer 1

“Balanced Anesthesia” - uses mostly IV drugs to induce anesthesia + accelerate the excitation phase with inhaled anesthetics to maintain anesthesia

Total Inhalation Anesthesia - mostly used in children

Total IV Anesthesia (TIVA) - usually used in smaller interventions

Question 2

List the IV anesthetics

Answer 2

Propofol and Fospropofol
Etomidate
Ketamine
Thiopental
Midazolam

Opioids:
Fetanyl, Sufetanyl, Remifetanyl

Antispychotics:
Haloperidol, Droperidol

Question 3

What is neuroleptic analgesia

Answer 3

Combination of opioid analgesic (i.e. fentanyl) with “neuroleptic” / antipsychotic (i.e. droperidol)

Produce a “detached, pain-free” state.

Results in immobility, analgesia and a variable degree of amnesia. Rarely used today.

Original combo was haloperidol and phenoperidine.

Question 4

Propofol uses and mechanism

Answer 4

Enhances GABAa
Used for induction AND maintenance.

Sedative, hypnotic, anterograde amnesia, and antiemetic effects

No analgesic effects.

Anti-emetic effect helps prevent aspiration pnemonia

Question 5

Propofol SEs

Answer 5

Strong respiratory depression

Strong vasodilation of vein and arteries, large MAP drop.

Long propofol infusions cause acidosis for resp depression.

Rare long infusions: Propofol inf syn. Rhabdomylosis, acidosis, hepatomegaly, and kidney failure.

Question 6

Ketamine uses and mechanism

Answer 6

Inhibits NMDA receptors
Used in induction

Causes dissociative anesthesia, Open eyes with a nystagmus.

Also analgesia and amnesia

Good for small operations, especially in children or disabled people who may have bad compliance - dissociative.

Question 7

Ketamine SEs

Answer 7

Respiratory Stimulation and bronchodilation

Also Cardiac stimulation

Hallucinations and emergence reactions, vivid dreams.

Question 8

Etomidate uses and mechanism

Answer 8

GABAa potentiation.
Rapid effect, 30-60s
Used only for induction

Has only minimal cardiac and respiratory effects.

‘Stabilizes’ the cardiovascular system and is a good induction anesthetic for patients with hypovolemia or heart problems.

Question 9

Etomidate SEs

Answer 9

Potent, long lasting adrenocortical suppression for several hours after use.

Need to make sure cortisol doesn’t drop too low

Post-op nausea

Myoclonic twitches and jerks.

Question 10

Thiopental mechanism and use

Answer 10

Potentiates GABAa, increasing the duration of channel opening.

Least often used.

Has profound cardiac and respiratory suppression, and decreases ICP due to constriction of cerebral vessels.
Can also cause laryngospasm.

THIS is its main use, and used in patients that have cranial masses or compressive lesions.

Question 11

Thiopental kinetics

Answer 11

Ultra rapid, very lipophilic with
onset 30 seconds LOC 60s.
lasts 5-10 minutes
Redistribution to adipose and muscle.

Question 12

Benzodiazepines for anesthesia

Answer 12

Midazolam - Also very short acting, and can be used for induction of more significant surgeries.

Diazepam, Lorazepam - longer acting

Benzos used as concious sedation for minor procedures, colonoscopy.
i.v.

Question 13

The fuck are the ‘perioperative medications’

Answer 13

Benzodiazepines - for anxiolytic and amnesia-producing effects

Analgesics

Antiemetics - including anti-emetic effects of propofol; to ↓ anesthesia/analgesic-induced emesis

Antimuscarinics - to ↓ parasympathetic functions, intubation gag reflex, atropine is used

CV medications - β blockers etc. are used to modulate CV activity during surgery

Prokinetics post-operatively