Intravenous Anesthetics

Question 1

Intravenous anesthetic are defined as….

Answer 1

Agents that induce loss of consciousness in a one arm-brain circulation time.

Question 2

Uses:

Answer 2

Induction - rapid
Maintenance
Sedation during ICU and regional anesthesia
Treatment of epilepsy

Question 3

Gaba receptor structure

Answer 3

Pentamer
2 alpha
2 beta1 gamma

Question 4

Gaba funtion

Answer 4

Amnesia
Depress spinal reflexes
Hypnosis

Question 5

Thiopental is…

Answer 5

Sulfur analogue of oxybarbiturate pentobarbital
Pale yellow powder
Vial contains sodium carbonate 6% by weight
2.5% solution stable for many days and needs to be bacteriostatic due to alkaline pH

Question 6

Thiopental inductions dose

Answer 6

3 to 7 mg.kg-1

Question 7

Thiopental duration

Answer 7

5 to 10 minutes

Question 8

Thiopental most important effect?

Answer 8

Acute porphyria crisis

Question 9

Does thiopental affect metabolism and elimination of other drugs?

Answer 9

Yes it increases it

Question 10

Intra-arterial injection of TP is a serious condition why?

Answer 10

It is meant to be IV
It causes endothelial damage
Pain
Delayed or absent sleep
Blanching or cyanosis
Loss of peripheral pulse
Arterial thrombosis with gangrene

Question 11

Treatment for intraarterial injection of TP

Answer 11

Stop injection and leave needle in
Dilute with saline
Give local anesthetics &/or vasodilator (papaverine)
Start IV heparin
Intraarterial injection of hydrocortisone
Postpone surgery

Question 12

Propofol
Describe

Answer 12

Phenol derivative
Highly lipid soluble
1% or 2% lipid-water soluble
Weak organic acid
Liver metabolism and extrahepatic metabolism
pKa 11
Almost entirely unionized at pH 7.4

Question 13

Propofol dose

Answer 13

1-2mg.kg-1

Question 14

Propofol effects

Answer 14

Bradycardia
Decreases BP and myocardial contractility
Fat overload syndrome (Hyperlipidemia, fatty infiltration)
Green urine and hair
Antiemetic
Hpypotension
Respiratory depression Leading to apnoea
Excitatory effects in 10%

Injection into small veins is painful - reduce using lidocaine

Question 15

Propofol infusion syndrome clinical features

Answer 15

Metabolic acidosis
Rhabdomyolysis
Renal failure
Cardiac failure

Question 16

Advantage of propofol

Answer 16

Optimal sedation level
Antiemetic

Question 17

Propofol metabolism

Answer 17

Liver metabolism- eliminated as sulfur &/or glucuronide conjugates in urine
Extrahepatic metabolism
Elderly- lower Vd and lower clearance, lower doses needed

Question 18

Adverse effects of propofol

Answer 18

Iv injection site pain
Hypotension
Hypoxia
Lipidemia
Green discoloration of urine (& hair)

Question 19

Ketamine general description

Answer 19

A phencyclidine derivative
Racemic mixture- S+ (more potent)
R- enantiomer
Water soluble, forms acidic solution (pH 3.5-5.5)
Dose: 1-2 mg/kg IV

Question 20

Systemic effects of ketamine

Answer 20

Normotension/hypertension
Tachycardia
Airway reflexes & tone maintained
Bronchodilation
Emetogenic
Dissociative anesthesia, analgesia, hallucinations

Question 21

Ketamime maim effect

Answer 21

Produces sympathetic nervous system stimulation- increase adrenaline and noradrenline

Question 22

Ketamine effect on ICP

Answer 22

INCREASE!!!!

Question 23

Etomidate dose
And formulation

Answer 23

0.3mg/kg
Prepared as 0.2% solution
Contains 35% propylene glycol for stability and reduction of irritant properties

Question 24

Etomidate effects

Answer 24

Least cardiovascular effects
Suppress adrenocortical function
Increase in mortality when used as an infusion to sedate septic patients in ICU

Question 25

Etomidate side effects

Answer 25

Pain on injection Excitatory movements Nausea Vomiting Porphyric crisis

Question 26

Benzos characteristics

Answer 26

Enhance gaba transmission in CNS Lipid soluble (except midazolam) Anterograde amnesia Anticonvulsant activity Diazepam 5-20 mg Midazolam 1-5 mg

Question 27

Sodium thiopental:

Answer 27

Pale yellow powder 3-7mg/kg 30-40s 5-10m Enhances GABA-A Decreases CO, BP w/ reflex tachycardia Resp. depression Laryngospasm, bronchospasm Decreases cerebral O2 consumption, cerebral blood flow, cerebral metabolic rate Can exacerbate porphyria

Question 28

Effects of sodium thiopental:

Answer 28

Decrease CO, BP w/ reflex tachycardia Dose-dependent respiratory depression May cause laryngospasm and bronchospasm Decrease Cerebral O consumption, decrease cerebral blood flow, decrease cerebral metabolic rate

Question 29

Favorable aspects of IV anesthetics:

Answer 29

Fast onset Avoids the excitatory phase

Question 30

4 IV anesthetics:

Answer 30

Propofol, etomidate, ketamine, thiopental,

Question 31

5 Inhalational anesthetics:

Answer 31

Nitrous oxide, isoflurane, sevoflurane, desflurane, xenon

Question 32

Propofol is presented as a _____ due tompoor water solubility

Answer 32

1% or 25% aqueous emulsion

Question 33

TIVA indications:

Answer 33

- Risk of MH - Long QT syndrome - History of severe PONV - Thoracic surgery - Patients w/ anticipated difficult intubation/extubation - Neurosurgery - Myasthenia gravis/ neuromuscular disorders - Non-theatre disorders - Day-case surgery - Patient choice

Question 34

Propofol only TIVA dose: Mixture dose:

Answer 34

2-2.5 mg/kg 1 mg/kg

Question 35

Dexmedatomidine:

Answer 35

alpha-2 agonist anxiolytic, sedative, analgesic, sympatholytic (respiratory depression)