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Question 1

Extubation criteria

• TV
• VC
• NIF
• PaCO2
• RR
• Tetanus time
• Head lift time
• RSBI

Answer 1

TV > 5cc/kg
VC > 10cc/kg
NIF > -20
PaCO2 < 50
RR < 30
Tetanus 5 sec
Head lift 5 sec
RSBI (RR/TV in liters) < 105

Question 2

Naloxone dose intra-op for delayed emergence

Answer 2

40 mcg boluses

Question 3

Flumazenil dose intra-op for delayed emergence

Answer 3

0.2 mg q1min up to 1 mg

Question 4

Neostigmine:

• Onset
• Peak time
• Duration

Answer 4

Onset = 5 min
Peak = 10 min
Duration = > 1hr

Question 5

Phenylephrine effect on coronary blood flow

Answer 5

Increased SVR -> increased CPP –> increased coronary flow

Mild coronary vasoconstriction is OVERRIDDEN by nitric oxide release –> maximal vasodilation

Question 6

Catecholamine metabolism in liver vs neurons

Answer 6

Liver: COMT -> MAO
Neurons: MAO -> COMT

Both: end product = VMA

Question 7

3 levels of dopamine gtt dosing

Answer 7

Low (< 3) = DA1 = diuresis (renal artery vasodilation)
Med (3-5) = DA1 and Beta = increased C.O. but increased O2 consumption more than delivery
High (10-20) = Alpha-1 dominates = decreased RBF

Question 8

Dopexamine MoA

When not to use

Answer 8

B2, DA&raquo_space;> B1 (opposite of Dobutamine)

• Decreased SVR, mildly increased HR and contractility –> increased C.O. and SV (IF BP ok)
• Increased RBF (IF BP ok)

Do NOT use if having BP problems already

Question 9

Dobutamine on alpha-1, beta-1, and beta-2

Answer 9

Beta 1 = strong –> increased C.O.
Alpha-1 = Beta 2 –> maintained SVR (slightly lower)
Result = increased C.O. but not enough to overcome decreased SVR

Question 10

Explain metabolism of nitroprusside and effects

Answer 10

1. Goes into cell and takes electron from Hb iron (Fe2 -> Fe3) = creates metHb
2. Extra electron causes breakdown of nitroprusside into N.O. and CN-
3. N.O. produces vasodilation via cGMP
4. CN- binds to (1) metHb -> cyanmetHb, (2) thiosulfate -> thiocyanate, or (3) electron transport chain
5. Thiocyanate causes toxicity

Question 11

Explain treatments for nitroprusside toxicity

Answer 11

Goal = increase binding capacity for CN- to get it away from electron transport chain

1. Sodium thiosulfate –> more thiocyanate production
2. Sodium nitrite -> metHb -> cyanometHb
3. CyanometHb treated w/ methylene blue (need sodium nitrite first)
4. Increase O2 availability (mildly effective)

Question 12

Hypoxia shortly after nitroprusside treatment (esp in ARDS)

Answer 12

Vasodilation = decreased ability for HPV = shunting