Accrac Notes

Question 1

What is the zero sum game of tissues that contributes to ICP?

Answer 1

3 tissues:
Brain parenchyma
Blood
CSF
With an unchanged ICP, changes in one affect the others

Question 2

What is the range of doses for mannitol for treating ICP?

Answer 2

Big range, no agreed dose
Between 0.25mg/kg to 1mg/kg
Caution in HFrEF patients!

Question 3

What are options in treating ICP?

Answer 3

Hyperventilation (reduce PaCo2 to decrease blood flow)

Mannitol (hyperosmosis to decrease intraparenchymal fluid)

Hypersonic saline (similar)

Lasix (decrease intravascular fluid)

Steroids (decrease swelling)

Question 4

What are vapor pressures of halothane, enflurane, sevo, isoflurane, desflurane

Answer 4

HI-SE

HALOTHANE= 240
ISOFLURANE

SEVO = 160
ENFLURANE

Desflurane 600

Question 5

Which gases DO NOT use variable bypass vaporizer

Answer 5

Nitrous oxide and desflurane because VP is very high

NO is in tank or piped in

Deslfurane is too Unstable since favorite Pressure is close to atmospheric pressure which means it’ll actively boil at STP and you can’t control delivery

Uses tech9 vaporizer, heats desflurane to 39degrees and increases VP so that entirety is gaseous
No bypass chamber, so all gas is already vaporized, dialed % gas will always give that % and will decrease dose in higher altitude

(Variable bypass vaporizer with increase the % molecules that are vaporized at higher altitude but the dose remains same)

Question 6

Volatile anesthetic uptake and correlation with blood-gas coefficient

Answer 6

Higher blood solubility will cause gas to leave alveoli and take longer for Fa/Fi to rise which means inhaled induction takes longer (this is higher blood-gas coefficient)

Shorter if low blood solubility since gas builds up faster in alevoli and speeds up induction (low blood-gas coefficient)

What occurs in alevoli is equal to what occurs in brain

Question 7

2nd gas effect of NO

Answer 7

NO is taken up faster than inhaled, so increases % of other gases

Question 8

Precautions of nitrous oxide

Answer 8

Can expand rapidly in enclosed spaces ie (eye gas, ear gas, pneumothorax)

Question 9

Why is inhaled induction faster in infants

Answer 9

Increased alveolar ventilation and lower FRC

Question 10

How does cardiac output affect inhaled induction speed?

Answer 10

Lower cardiac output will allow for FA to increase faster and thus increase speed of induction

Question 11

What are the estimated B:G coefficients of halothane, isoflurane, sevo, des, and NO

Answer 11

Halothane 2.4 = high solubility
Isoflurane 1.4

Sevo 0.6 = low solubility
Des 0.4

NO 0.47

Question 12

How does alveolar ventilation affect inhaled induction?

Answer 12

Increased ventilation will increase inhaled induction speed, this has more effect in highly soluble gases (halo/iso)

Question 13

How does R>L intra cardiac shunt affect both inhaled and IV induction?

Answer 13

Dilute blood so slows inhaled induction and affects poorly soluble agents more so than high solubility

Increases speed of IV induction, bypasses lungs and straight to brain

Question 14

How does L>R shunt affect induction both IV and inhaled?

Answer 14

Little effect on both

Question 15

How does V/Q mismatch affect inhaled induction?

Answer 15

Mismatch slows inhaled induction, but slows more for poorly soluble gases since highly soluble gases can be replaced by increasing MV

Question 16

What are mmeq of Na in NS vs LR

Answer 16

Lr 130
Ns 154

Question 17

How does NS cause hyperkalemia?

Answer 17

NS causes metabolic acidosis causing potassium to shift out if cells, even though NS does not have K it can cause hyperkalemia

Question 18

Metabolism of amide vs Ester local anesthetics

Answer 18

Amide is liver, Ester is pseuocholiesterase in plasma