COMP 15 Flashcards by Cindy Ehret

What are the ASA guidelines for pts taking 82 mg regarding neuraxial anesthesia?

Continue taking ASA
Proceed with neuraxial anesthesia

By themselves, ASA and NSAIDs do not increase the risk of spinal hematoma. This assumes a normal pt with normal coagulation profile

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What is the waiting period to proceed with neuraxial anesthesia in a pt taking Plavix?

7 days

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If the initial dose of warfarin was given > 24 hrs preop to a block or more than 1 dose was given, how should you proceed?

Check PT/INR and document

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If a single dose of warfarin was given < 24 hours preop, how should you proceed?

It should be safe to proceed..but I would still check PT/INR

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Minidose SQ heparin is a contraindicaion to neuraxial. True or false?

False

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When should blocks be performed in pts receiving heparin therapy?

1 hr or more before scheduled dose

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When should an epidural catheter be removed for pt receiving heparin treatment?

1 hour prior to treatment OR

4 hrs following treatment

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When should needle placement for neuraxial be performed for pt receiving LMWH?

At least 10 hrs after dose

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If a pt is receiving fibrinolytic drugs (tPA, streptokinase, urokinase), what should the protocol for receiving neuraxial anesthesia be?

Neuraxial is contraindicated in these pts

tPA = tissue plasminogen activator

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How do you manage hypotension associated with epidural analgesia?

fluid administration and pressor therapy

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What is the primary cause of hypotension associated with a high spinal?

decreased preload –> decreased CO

high spinal associated with sympathetic blockade and decreased HR associaed with cardioaccelerator fibers T1-T4 being blunted

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What are ways to minimize the degree of hypotension?

Volume loading (10-20 cc/kg)

Left uterine displacment

Head-down position

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If fluid administration is not suffient to treat hypotension in pt with neuraxial block, what pressors should be used?

Phenylephrine

Ephedrine

Epi (5 - 10 mcg IV)

For decreased HR, give atropine.

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What is the order of loss of modalities with spinal anesthesia?

small fibers > large fibers

myelinated fibers> non-myelinated

sympathetic block > sensory > motor

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Why may the paramedian approach to neuraxial be indicated?

pt cannot be positioned easily due to arthritis, kyphosis

calcified ligaments

thoracic epidural needed (longer spinous processes)

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If a solution has a baricity ratio > 1, what does this mean?

Hyperbaric solution which means that it will sink with gravity in the CSF

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Is LA + dextrose hyper or hypo-baric?

hyperbaric

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Is LA + sterile water hyper or hypo-baric?

hypobaric

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How does pregnancy affect CSF baricity?

decreases it

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At what level does the iliac crests lie?

L3-L4

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What is the physiological mechanism preceding asystole during spinal anesthesia?

High spinal sympathemectomy (blockade of cardioaccelerator fibers) leaves vagal tone unopposed

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What are the advantages of neuraxial anesthesia?

Metabolic stress response to surgery is decreased

Pulmonary compromise is decreased

Less blood loss

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What is the order of sensitivity of nerve fibers from most sensitive to least sensitive?

B fibers (myelinated but physically thicker than C fibers, responsible for sympathic tone)

C fibers (unmyelinated, responsible for pain)

A (delta) responsible for temperature

A (gamma) responsible for propioception-sense of movement

A (beta) responsible for touch, pressure

A (alpha) responsible for motor movement

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What is the molecular form of injectable LA consist of?

benzene ring (lipophilic) with a tertiary amine (hydrophilic)

the bond between the two determines the class of LA, ester or amide

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What are the amide LAs?

Ones with "i" before the "-caine"

How are the amide LAs metabolized?

Cyt 450 metabolism, i.e. liver

Which class of LAs are more stable?

amides

What LA is an exception to all the others and how?

cocaine is mostly metabolized in the liver

How are ester LAs metabolized?

plasma cholinesterases and are very unstable

What may cause allergies to ester LAs? What may cause allergies to amide LAs?

PABA (para-aminobenzoic acid) methylparaben similar to PABAs found in mulidose preparations

What does the onset time of LAs depend upon?

lipid solubility relative concentration pka --relative nonionized form (lipid) to ionized form (water soluble)

What happens when the pH \< pka of LA?

Inflamed tissues have lower pH --\> base (LA) + acid (tissue) = increased ionized form of LA --\> Less non-ionized form --\> less potent

How does bicarb increase effectiveness of LA?

Increases local pH --\> less ionized form of drug --\> faster onset

What should the pka be relative to pH in order to have the highest efficacy?

pka ~= pH Most non-ionized form of drug exists under these conditions

What happens to LA onset if the pH \>\> pka?

Onset takes much longer since most of the drug is in lipophilic form

What does increased lipid solubility correlate to?

increased potency

What does the dissociation constant, or, pka a LAs correlate with?

time of onset

What type of LA molecules will not penetrate neurons?

Quarternary, water soluble state Must be in tertiary lipid soluble state to penetrate cell membrane

What does the pka of LAs represent?

the pH of which 50% exists in quaternary form and 50% exists in tertiary form

What will occur to duration of amide LAs if hepatic flow is decreased?

longer duration of action

What occurs to duration of action with increase protein binding?

longer duration of action

How does epi effect the onset time?

It doesn't

What severe cardiotoxic reactions can bupivicaine cause?

arrhythmias AV heart block V-tach V-fib hypotension

For what LA is intralipid administered?

bupivicaine

\*What is the initial bolus of intralipid (20%) to treat LA toxicity?\*

1.5 mg/kg over 1 minute

What should be the initial setting for a nerve stimulator need to be for peripheral nerve blocks?

0.2 - 0.5 mA

What nerves are blocked for ankle blocks used in foot surgery? (5)

* PT (posterior tibial) * Peroneal * Superficial peroneal * Saphenous * Sural

Which regional anethesia will most likely produce ipsilateral diaphragmatic paresis or paralysis?

interscalene block because it can hit the phrenic nerve

When is an interscalene block indicated?

shoulder surgery

What nerve is commonly missed in an interscalene block?

ulnar nerve

\*How do you manage cuff pain 40 mins after the administration of a Bier Block?\*

the most effective way is rotating the tourniquet by changing the site of tourniquet pressure from proximal to distal when the pressure is on the anesthetized portion of the arm Answer: Inflate distal cuff THEN deflate proximal cuff

During a Bier Block, what if the tourniquet pressure inflated to?

250 mmHg or 100mmHg above systolic pressure

How much LA is injected while doing a Bier Block?

~50cc of 0.5% lidocaine

What is the purpose of a femoral vent hole when methylmethacrylate is used?

to prevent increased intramedullary pressures --\> fat embolism

How do you manage tourniquet pain?

* Deflate cuff for 10-15 minutes then reinflate cuff * give vasodilators to lower BP Tourniquet pain occurs about 30-60 minutes after cuff inflation

What is a compound fracture?

An open fracture that occurs when there is a break in the skin around a broken bone. The bone does not need to be outside the skin, there just needs to be a break of the skin to open air

Why does a compound fracture represent an emergent medical procedure?

It is at high risk for infection

\*Hypotension occurs post-op in a pt receiving epidural analgesia with infusion of bupi + meperidine. What actions should you take first?

* Assess and manage IV volume * Measure hematocrit and manage blood volume * Change infusion to dilaudid * Last actions: stop epidural or add IV infusion of pressors

\*What is the first modality to be lost upon onset of spinal anesthesia?

sympathetic blockade

\*What is the advantage of spinal over GA for vaginal delivery?\*

Reduced risk of aspiration

\*Which amide LA has the most rapid onset when used for spinals?\*

Lidocaine

\*A Bier block on an upper extremity is appropriate for surgery lasting up to _____ minutes.\*

60 minutes

What problem is depicted?

Pneumothorax, collapsed lung on left

What are the more common sizes for spinal needles?

22 - 27 gauge

What is potency?

The amount of drug required to achieve a defined effect

In what position do you place a pt for a Bier block?

supine

What drug is used for a Bier block?

Lidocaine

What does this CXR depict?

sub-q emphysema

What is the rate and rhythm?

v tach rate 180...not in this pic though

What is the most prevalent etiology of arterial hypoxemia?

low V/Q = shunt high V/Q = deadspace

What is depicted in the CXR?

pneumonic infiltrates

What is the current output of the stimulator depicted?

0.5 mA

What is normal CSF density?

1.003

Which of the following factors most often dictates selection of outpatient surgery? ## Footnote Allergies ASA status co-morbidities patient choice pharmacologic considerations reimbursement considerations surgeon preference

reimbursement considerations

What drug will NOT reverse spasm of the sphincter of oddi?

Neostigmine

How much buffer is available in sodium bicarbonate 8.4%?

1 meq/ml of buffer for 84 mg of sodium bicarb

What is a compound fracture?

bone penetrates the skin

Why does a compound fracture represent an emergent surgical procedure?

risk of infection

What is the best method of restoring blood pressure for a trauma patient who has suffered significant hemmorhage?

give blood

What is the best plan for emergence for adult who has undergone total laryngectomy?

spontaneous ventilation (during anastomosis) + trach collar to normal pacu

If: ## Footnote ``` FiO2 = 0.21 SaHbO2 = 86% SaHbCO = 0.4% SaHbMET = 0.2% PaO2 = 72 mmHg PaCO2 = 38 mmHg pH = 7.36 Hb = 17.6 ``` What is the acid-base state? What is the acid base condition?

Normal Normal

For the toxicity of which LA is intralipid administered?

bupivicaine

What is the YAG laser's advanage over the CO2 laser for airway surgery?

attracted to dark pigment (Hb) and helps with controlling bleeding

What total score meets fast-track criteria for bypassing the recovery room?

12 or greater

What score obviates fast tracking?

score of zero in any category

What are the guidelines for neuraxial anesthesia in pts taking daily aspirin 81 mg?

continue with neuraxial

What should the inital current setting be for a nerve stimulator being used for a peripheral nerve block?

0.2 - 0.5 mA

Which regional anesthetic technique will most likely produce ipsilateral diaphragmatic paresis or paralysis?

Interscalene block b/c can hit phrenic nerve

How do you manage cuff pain occurring 40 min. after adminstration of a Bier block?

inflate distal cuff and deflate proximal cuff

What narcotics are prohibited for administration in PACU to outpatients?

None

What led to the propofol shortage that occured in the fall 2009?

contamination of product

Wha is the drug of choice to pharmacologically support the pt with acute cardiac tamponade? How is it administered?

Isoproterenol Infusion

Which VQ type of lung unit produces hypoxemia associated with post-op atelectasis?

low V/Q

What are the ASA guidelines for adults for NPO status for clear liquids?

2 hours

How should the chest tube placed in a pt following pneumonectomy be managed in PACU?

leave clamped

Which way will the following reaction be driven as blood becomes more acidemic? R-NH3 \<-- --\> R-NH2 + H+

to the left

A pt sustained blunt neck trauma. There is a high index of suspicion for laryngeal fracture. General is planned for neck exploration. The pt is awake and alert with stable VS. Oxygenation and ventilation are satisfactory. What is the most appropriate airway management for this pt?

Trach

The pt becomes dyspneic and stridorous and sat begins to decrease. What is the most appropriate airway management for this pt?

HPOV

Where is the mastoid bone located?

behind the ear