Inhalant anesthesia 1 & 2

Question 1

What is Dalton’s law of partial pressure

Answer 1

total pressure of a gas mix is equal to sum of partial pressure of the individual gases

Question 2

solubility

Answer 2

expressed as a partition coefficient describes capacity of a given solvent to dissolve anesthetic gas

Question 3

What is blood-gas partition coefficient

Answer 3

describes amt of anesthetic in blood vs. alveolar gas at equal partial pressures

Question 4

What is the significance of knowing the amount of alveolar gas

Answer 4

the anesthetic in alveolar gas represents brain concentration this is location of effect anesthetic dissolved in blood is pharmacologically inactive!

Question 5

How to incr alveolar delivery of anesthetic gas

Answer 5

Incr inspired anesthetic concentration:

1. incr vaporizer setting
2. incr fresh gas flow

Incr alveolar ventilation:

1. incr minute ventilation

Question 6

how to decrease removal of anes gas from alveoli

Answer 6

decr blood solubility of anesthetic

Question 7

What is Minimum Alveolar Concentration (MAC)

Answer 7

Minimum alveolar concentration of an anesthetic that prevents movement in 50% of pts exposed to a noxious stimulus

Question 8

What ensures immobility in 95% of patients

Answer 8

1.2-1.4 x MAC

Example: 1.2MAC of iso = 1.2 x 1.3 = 1.6%

Question 9

What are CV effects of inhalants

Answer 9

Decrease:

CO

BP

SVR

Contractility (inotropy)

No change or Increase:

HR (chronotropy)

Question 10

What are respiratory effects of inhalants

Answer 10

Decrease ventilation

Bronchodilation

irritating odor: desflurane & iso

least irritating odor: sevo

Question 11

What are neurologic effects of inhalants

Answer 11

Incr ICP @ >1 MAC (incr cerebral blood flow)

Decr cerebral metabolic rate

acts on brain & SC to produce immobility (not analgesia)

suppress seizure activity (except Enflurane)

Question 12

What are renal effects of inhalants

Answer 12

Decr GFR & renal blood flow

Renal failure (methoxyflurane)

Question 13

what is Compound A

Answer 13

Produced from sevoflurane breakdown in CO2 absorbent (baralyme > soda lime)

Nephrotoxic in rats

Question 14

What are hepatic effects of inhalants

Answer 14

decr liver blood flow & O2 delivery (related to decr CO)

Halothane can cause hepatotoxicity 2 types:

incr liv enzymes (mild, self limiting)

Halothane hepatitis = immune mediated often fatal

Question 15

What inhalant can cause malignant hyperthermia

What spp most affected

Whats first sign

Tx

Px

occurance rate

Answer 15

Halothane

Pigs

Rapid incr in EtCO2

Dantrolene (muscle relaxant)

Poor-grave despite tx

extremely rare

Question 16

What can be a consequence of N2O use

Answer 16

diffusion hypoxia when N2O d/c

prevent by providing 100% O2 for 5-10 minutes after stopping N2O

Question 17

What are 3 anesthetic related common complication of inhalants

Answer 17

Hypotension

Hypoventilation

Hypothermia

Question 18

What is considered hypotension in SA

LA

what is corresponding number on Dopper BP

Answer 18

MAP < 60 mmHg

MAO < 70 mmHg

80 or 90 respectively

Question 19

What is the most appropriate & effective tx for hypotension during inhalant anesthesia

Answer 19

1 evaluate pt & turn down vaporizer if pt is too deep for current level of stimulation

if pt is light, add MAC sparing drug, then turn down vaporizer

Question 20

What is considered hypventilation with inhalant anes

Answer 20

PaCO2 >40 mmHg OR EtCO2 >45 mmHG

Question 21

What is appropriate tx for hypoventilation

Answer 21

1 evaluate pt & turn down vaporizer if pt too dep for curren level of stimulation

Question 22

What is considered hypothermia during anesthesia

Answer 22

Temp < 97° F or 36° C

Question 23

What is appropriate tx for hypothermia

Answer 23

Prevention is more effective than tx!

various ways:

BAIR hugger

bubble wrap feet

cover

warm water pad

etc.

Question 24

What will a CO2 rebreathing waveform look like on capnograph

Answer 24

waveform does NOT return to baseline (0) between breaths