Board Review part deux Karl Wagner MD June 21, 2007

What happens if you tip the vaporizer? What should you do next?

If you tip it you don’t know how much agent you will give. Turn O2 up to 10 L for 30 mins.

Volatile anesthetics How much gas comes from 1 ml of isoflurane?

200 cc

Quick, someone draw a circle system.

Circle System

Mapleson circuits Can any one draw them?

Which circuit do we use for spontaneous respiration? Which do we use for controlled ventilation? Why does it matter?

A dog can bite. This is a spontaneous event. Dog bites ache. This is now a controlled situation.

How fresh is fresh? What does the fresh gas flow need to be for each of these circuits?

2-3x Vt, you will note if you look at the circuits that only the A (spont) and the D (cmv) use flows this low. The others use much higher flow rates.

CO2 absorber follow up. How big does the canister have to be?

Must hold entire Vt.

How big should the crystals be? Some lonely guy figured you should have a mix of small and large. The small increase surface but also resistance. This concept has been tested. It will be a slam dunk for you.

What are the wavelengths of the pulse ox?

940 (oxy) 660 (deoxy)

What is normal CBF?

50 cc/100 g brain/min At 20 you get brain acidosis and change in eeg At 15 you have isoelectric eeg At 6 you have infarction

Interscalene block What operations is it good for?

Shoulder, upper arm

Why do all of Rahim’s patients have hemidiaphragm paralysis after his blocks?

You always tank the phrenic nerve. You can also get the recurrent laryngeal. What else can happen with these blocks?

They might work, that is good Some bad stuff includes: spinal, pneumothorax, seizure,

Which nerve is often missed with the interscalene block?

ulnar

Where do intrathecal opiods work?

In the substantia gelatenosa.

Where is my stellate ganglia?

It sits near the origin of the first rib off of the C7 vertebra. What is Chassaignac’s tubercle?

Process on C6 which is often easier to palpate.

Why would I want to block my stellate ggl?

Sympathectomy to upper extremity. How do I know it worked?

Horner’s syndrome (ptosis, miosis, anhydrosis) Nasal stuffiness ipsilateral side Flushing of conjunctiva and skin Temp increase on arm*****

Check out these blood vessels. Carotid, jugular and one other?

Don’t forget the vertebral artery. That is the trick for the boards!

Where is my celiac plexus? The question was purely anatomical….

Anterior to aorta Medial to IVC Level L1

Why would I stick a needle there?

Mostly cancer pain, it is sensory and sympathetic fibers. Used for pain from lower esoph sphincter to splenic flexure. Also liver, PANC, and kidneys.

These patients always get diarrhea, they can also have postural hypotension.

How much local anesthetic can you get?

The ones that matter seem to be Lido (#1) and bupi. Lido 4 mg/kg (7 with epi) Bupi 3.5 mg/kg ((3.5 with epi (notice the trick))

For a bonus, which local anesthetic is associated with methemoglobinemia?

Prilocaine Treat with methylene blue.

Ankle block is good for at least 3 questions

What nerve do I hit if I go through the artery?

Which nerve is up? Which nerve is down?

Medial Ulnar Radial is behind the artery.

The questions for the upper extremity end up being where do you stick the needle to give rescue blocks? When your ax or interscalene fail now what?

Block at elbow and wrist. Do you know where to inject?

This will be there for sure.

West Zones

Pulmonary volumes

Remember VC – cc/kg Vt – 5-7 cc/kg FRC – 40 cc/kg

Dead space is where no one can hear you scream. Vd/Vt = (PaCO2-PeCO2)/PaCO2 Why do I care if Douglas has his bag? You will be asked to calculate the ratio of dead ventilation. The norm is what?

0.3

How is atracurium metabolized?

Hoffman elimination

What is a dibucaine number? Should mine be high or low?

Dibucaine inhibits cholinesterase. When it is 80% inhibited this is normal. If it is 20% then I am screwed. Why? Sux will last longer. How long?

It ends up having a one hour half life if eliminated by non specific esterases in body.

If I have four twitches how many receptors can still be blocked?

70%

What should I do when Dr. Brown tells me he just injected Thiopental in the a line? Should I pat him on the back affectionately?

That can cause severe pain and vasospasm that can lead to gangrene. Flush with saline, give lido and do a sympathetic block to cause vasodilation. Pt is screwed.

Keep reading. All pictures are from Miller Anesthesia (from MDConsult) or Study hard and remember to tip the waitstaff.