Inhaled anesthetics Yusuf

Question 1

Factors which increase MAC:

Answer 1

• Hyperthermia
• Hyperhtyroidism
• Hypernatremia
• Drugs that increase catecholamines (MOAi’s, tricyclic antidepressants, cocaine, amphetamines)
• Chronic ethanol abuse

Question 2

Factors which decrease MAC:

Answer 2

• Hypothermia
• Hyponatremia
• Pregnancy
• Lithium, lidocaine, a2 agonists
• PaO2 < 38mmhg
• Blood pressure <40mmhg
• Increased age
• Medications that decrease catecholamine levels (a-methyldopa, clonidine)
• Acute ethanol ingestion

Question 3

Nitrous oxide

Answer 3

• Colourless, odorless, sweet taste
• Noninflammable, nonirritating, low potency
• Very potent analgesic, but not a potent anesthetic
• No affect on HR and respiration
• Inhibits vitamin B12 metabolism
• MAC value is 104%

Question 4

Halothane

Answer 4

• Pungent odor
• CVS DEPRESSION (both BP and HR)
• Rapid, shallow breathing (decreased TV and increased RR)
• HUGE increase in cerebral blood flow
• CAUSE OF HEPATITIS
• Not used anymore XD

Question 5

Enfluorane

Answer 5

• CVS - decreases BP, increases HR
• Rapid, shallow breathing (decreased TV and increased RR)
• Increase in cerebral blood flow
• Toxicity - fluoride-induced nephrotoxicity
• Eliminated primarily by ventilation

Question 6

Isofluorane

Answer 6

• Sweet odor
• Decreases BP, mildly increases HR
• Irritates airways
• Increases cerebral blood flow

Question 7

Desflurane

Answer 7

• PUNGENT ODOR - not reccomended for mask induction
• Decreases BP, increases HR
• No sensitization to epinephrine
• Increases intracranial pressure

Question 8

Sevolurane

Answer 8

• Most commonly used
• Pleasent odor
• Rapid, shallow breathing (decreased TV and increased RR)
• Increase in cerebral blood flow
• Non-irritant
• Good bronchodilator

Question 9

Malignant hyperthermia:

Answer 9

• Caused by inhaled anesthetics and succinylcholine
• Autosomal dominant - loss of normal Calcium homeostasis
• Myoglobinuria, renal failure, rhabdomyolysis
• Increased metabolism - tachycardia, dysrhythmia, increased CO2, metabolic acidosis, pyrexia, DIC
• Muscle rigidity, masseter spasm, hyperkalemia
• Diagnose with the invitor contracture test - femoral nerve block, remove from the vastus medialis muscle
• Decreased SaO2, increased FiO2
• Tachycardia with a rise in minute volume or ETCO2
• Check core temperature before surgery
• GIVE DANTROLENE

Question 10

The pneumonic SALT can be used to remember the tools required for intubation:

Answer 10

S - Suction
A - Airway - oral airway
L - Laryngoscope
T - Tube - female size 7-8mm,
male size 8-9mm

Question 11

Types of blades:

Answer 11

Miller - striaght - used in pediatrics
Macintosh - curved - used in adults

Question 12

Endotracheal tubation complications:

Answer 12

• Tube malpositioning
• Tube malfunction or physiologic response to airway instrumentation
• Trauma
• Mucosal inflammation, ulceration, excoriation
• Laryngeal malfunction and aspiration

Physiological responses to intubation: hypertension, tachycardia, intracranial hypertension, laryngospasm