Anesthesia

Question 1

What are the types of anesthesia? Describe each.

Answer 1

General: suppression of activity in the CNS, unconsciousness and total lack of sensation.

sedation: inhibition of transmission of nerve impulses between higher and lower centers of the brain, inhibition of anxiety and memory.

regional: use of local anesthetics to make a portion of the body insensately by blocking transmission of nerve impulses between a part of the body and spinal cord.
- -peripheral: inhibits sensory perception within a specific location (nerve blocks)
- -central: local anesthetic delivered around the spinal cord and removes sensation of the body below the level of the block (spinal and epidural)

Question 2

What are the endpoints of anesthesia? Which medications are included in each “endpoint”?

Answer 2

Analgesia: opiates, local anesthetics, ketamine, NSAIDS

Amnesia: Benzos

Hypnosis: Barbiturates, propofol, etomidate

Immobility: muscle relaxants

Hemodynamic stability: beta blockers, sympathomimetics

Question 3

Risks of anesthesia?

Answer 3

Death, MI, PE, post op N/V

Question 4

ASA Classification:

• what is ASA?
• what does ASA classification mean?

Describe each ASA Classification:

• ASA I
• ASA II
• ASAIII
• ASA IV
• ASA V
• ASA VI

Answer 4

ASA = american society of anesthesiologists

ASA Meaning = classifies the likelihood of surgical or anesthetic complications.

ASA I:
-normal healthy patients.

ASA II:

• pt with mild systemic dz
  (e. g smoker, more than minimal drinking, pregnancy, obesity, well controlled DM)

ASA III:
-pt with severe systemic dz, not incapacitating
(E.g DM, poorly controlled HTN, distant hx of MI, CVA)

ASA IV:

• pt with severe systemic dz that is a constant threat to life.
  (e. g. recent hx of MI, CVA, cardiac stent)

ASA V:
-moribund pt who is not expected to survive without the operation.
(E.g. ruptured abdominal or throacic aneurysm)

ASA VI:
-pt who has already been declared brain-dead and whos organs are being remove for transplant.

Question 5

What are the types of regional anesthesia? describe each.

Answer 5

Regional anesthesia:
-infiltrative: local anesthetic injected in a small area to stop sensation.

• peripheral nerve block: local anesthetic injected near a nerve that provides sensation to a portion of the body.
• IV regional anesthesia: aka Bier block; dilute local anesthetic infused to a limb through a vein with a tournaquet placed to prevent the drug from diffusing out of the limb
• Central nerve blockade: infusion or injection of local anesthetic in or around a portion of the CNS (spinal/epidural)
• topical anesthesia: special formulat that diffuses through the skin or mucous membranes (EMLA patches)
• tumescent anesthesia: large amount of dilute local anesthesia infiltrated into the subQ tissue (used in liposuction)

Question 6

Neuroaxial anesthesia:

• aka
• CI
• what are the sites of injection?
• benefits?

Answer 6

aka: epidural/spinal/intrathecal

ContraIndications:

• patient refusal
• infection
• coagulopathy

Injection sites:
-Spinal anesthesia is injected L4-L5 (below L2)

-Epidural can go anywhere along the spinal column b/c they are not going beneath the dura.

Benefits:

• decreases surgical time
• decrease incidence of DVT or PE
• reduced stress response during surgery
• reduced platelet aggregation

Question 7

Neuroaxial anesthesia:

-complications

Answer 7

Complications:

• MC is post procedural HA
• spinal hematoma or abscess

Question 8

Nerves can be localized by what three tests for a regional block? (how do we locate nerve bundles)

What are the 3 MC brachial plexus blocks?

Answer 8

Paresthesia, nerve stimulation, US

Brachial plexus blocks:

• Interscalene
• subclavicular
• axillary

Question 9

Local anesthetics: 
Which medications fall under each of the following categories? And are they an ester or amide?
-Short duration of action 
-intermediate DOA 
-long DOA

Answer 9

Short:
-Procaine (ester)

Intermediate:
-Lidocaine, Mepivacaine (amide)

Long: Tetracaine (Ester), Bupivacaine, Ropivacaine (Amides)

Question 10

Drug concentrations are expressed as a %, so 0.25% bupivacaine = ____ mg/ml?

Epinephrine expressed as grams/ml, so 1:200,000 E = ____ ug/mL

How do we calculate the dose of local anesthetics?

Answer 10

% X 10 = mg/ml

0.25% bupivacaine = 2.5mg/ml

1 gram in 200,000 or 5ug/ml

Dose:
Volume X Concentration = Dose.

Question 11

if the conentration of local anesthetic is:
-low
-intermediate
-high
….what is being blocked? (sympathetic, sensory, motor?)

Answer 11

Low = sympathetic

Intermediate = sensory

High = motor

Question 12

Why add Epinephrine to local anesthetics?

Answer 12

prolong surgical anesthesia time

decrease peak serum levels

Intravascular marker

decrease surgical site bleeding.

Jens words:
Causes vasoconstriction so 1. it helps anesthetic stay there longer, thereby increasing Duration of Action. 2. also allows you to use less of the anesthetic agent in the area b/c of the vasoconstriction.

Question 13

When dont we add epinephrine to local anesthetics?

Answer 13

fingers/toes

penis

ear/nose

skin flap

when vasoconstrictive properties may compromise tissue perfusion

Question 14

What are the three main considerations when choosing a local anesthetic?

Answer 14

Which agent? - duration/onset/allergies

What concentration? volume/degree of blockade

Epinephrine?

Question 15

What are signs of local anesthetic toxicity?

Treatment of local anesthetic toxicity?

Answer 15

local anesthetic toxicity:

• dizziness
• tinnitus
• nystagmus, dysphria, shivering
• somnolence, muscle twitching
• seizures
• cardiac arrhythmias
• cardiovascular collapse

Tx of toxicity:

• stop injection
• call for help
• supportive care (ABC)
• 20% intralipid 1.5ml/kg IV bolus 0.25ml/kg.min (may repeat bolus 1-2x)
• cardiopulmonary bypass