Skin Surgery Flashcards
Max dose of lidocaine without epi
4.5 mg/Kg
Max dose of lidocaine with epi
7.5 mg/Kg
Max dose of lidocaine for children
half the dose of adults
what Electrosurgery uses a direct current to heat a probe
electrocautery
list two monoterminal forms of electrosurgery (high voltage low amperage)
Electrofulguration and Electrodessication
What is the difference between Electrofulguration and Electrodessication.
Electrofulguration tip does not touch the tissue and there is an arc, carbon eschar prevents deep destruction.
Name two biterminal forms of Electrosurgery
Electrocoagulation and Electrosection
What is the difference between Electrocoagulation and Electrosection
Both are low voltage high amperage, but Electosection is undampened current
what type a electrosurgery requires an indiferent electrode.
Electrosection
What temperature does melanocytic necrosis occur at?
-5 degree Centigrade
what is the pH of Lidocaine?
2.5 - 4.0
What are the three outcomes of adding bicarbonate to Lidocaine?
Raises pH with lowers pain
Lowers pKa which causes faster onset.
lowers protein binding which reduces duration.
At what blood pressure should you consider deferring surgery.
> 200/100
Which has a higher rate of infection suturing or secondary intention healing on the lower extremity?
secondary intention healing
What two things to do to prevent air embolism in open parietal emissary veins.
Keep patient prone
Use bone wax over openings.
What are the margins for excising a melanoma?
In situ .5-1cm
<1mm 1cm
1 to 2mm 1-2 cm
>2 mm 2cm
what are two advantages of a split thickness skin graft over a full thickness graph?
- can cover larger areas.
2. can survive better on poorly vascularized wound beds.
Name two devices to harvest split thickness graphs?
A Weck blade or a dermatome.
What % of skin surgeries get wound infections?
< 3%
Are wound cultures recommended for post op infections?
Yes
what are the for stages of healing in an acute injury such as Mohs surgery.
- hemostasis - fibrin and platelet plug form
- inflammation
- proliferation
- remodeling
During the inflammatory phase of wound healing what cell phagocytose pathogens, degrade debris, stimulate formation of granulation tissue and stimulate angiogenesis.
Macrophages
What excision surgical margins with a regular SCC gives a 95% clearance rate.
4mm margins
what excision margins with a high risk SCC > 2cm gives a 95% clearance rate.
6mm margins
What are the NCCN guidelines for non-Mohs excision of a SCC regarding margins.
4 to 6 mm margins.
What is the recurrence rate for SCC with Mohs at 5 years.
10%
what are margins for excisional bx of a suspected melanoma.
1-3 mm
Which is better for coagulation for a melanoma bx Aluminum Chloride or Monsels?
Aluminum Chloride
What is the INR therapeutic range?
2-3
Name two drugs that can lead to increased risk of dehiscence.
Sirolimus and Prednisone.
What is the tensile strength of collagen at one wk and three weeks?
3% and 20% at 1year it is 80%
What is the amount of lidocaine per Kilogram without epi. and with epi
4.5 mg/Kg without 7mg/Kg with epi
If you wipe Iodine with what it will remove it?
Alcohol - Use alcohol first.
Name an antiseptic that is resistant to removal by alcohol.
Chlorhexidine gluconate
Does Chlorhexidine gluconate bind to the stratum corneum?
yes
Is Chlorhexidine gluconate good for both viruses and bacteria.
Yes. Low concentrations are bacteriostatic, high are cidal.
Where is lidocaine removed from body?
Metabolized in the liver mitochondria by P450.
is lidocaine an amide or an ester?
amide
When might you give pre-op antibiotics?
skin infections and mucosal surgery.
What are the two antibiotics of choice and dosage for preop if there is a skin infection.
Cephalexin or dicloxacillin 2gms
For mucosal surgery what is the best pre op antibiotic.
Ampicillin. 2grms
What are two alternatives if you need pre op antibiotics and have a PCN allergic patient?
Clindamycin 600mg or
Azithromycin 500mg
What topical medicine can give someone methemoglobinemia?
EMLA cream
What type of patient is more likely to get methemoglobinemia from EMLA cream?
Baby less than a year old.
Someone with G6 PD deficiency
Someone taking dapsone or phenobarbital
What are the two drugs in EMLA cream
Lidocaine and Prilocaine both 2.5%
How does EMLA cream cause methemoglobinemia?
It is the prilocaine. It oxidizes Fe from Ferrous to Ferric state.
What is imbibition.
The first stage in the healing process of a graft. Lasts for 24 to 48 hours. I thin film of fibrin forms between graft and bed.
what is the least reactive non absorbable suture
prolene
what suture is best for running subcuticular closures due to low coefficient of friction and low reactivity
prolene
What is the problem with using betadine
must be dry to be effective and it is inactivated by blood.
what areas should chlorhexidine not be used
Hibiclens around eyes and ears. can cause keratitis and ototoxicity
what pre op cleanser has the highest rate of allergic contact dermatitis
Iodine Iodophor
Staphylococcal toxic shock syndrome occurs when in skin surgery
when there has been nasal packing or nasal surgery cultures are usually neg caused by a superantigen
how often are patients incorrect in identifying their surgery site.
25%
Maximum effect for hemostasis from epi in lidocaine is how many minutes
25minutes
Is aluminum chloride flammable
yes
what makes lidocaine less painful on injection warming or cooling?
Warming
what four things happen when you mix bicarbonate with lidocaine
- decrease injection pain
- increase time of onset
- shorten shelf life
- shorten duration of action
what is the ratio of 8.4% bicarb to Lidocaine with epi
1ml:10ml
What is the pH of plain Lidocaine
6 (it is less acidic that Lido with epi)
What is the pH of Lidocaine with epi
4.0 +- .5
at what blood pressure should you not do surgery and when do you send them to the ER rather than their primary care doctor.
> 200/110 If they have symptoms such as nausea, vomiting, headache, dyspnea, chest pain etc… send to ER otherwise schedule with primary care doc.
What is the first thing you should do if the blood pressure show malignant hypertension.
Check for proper size of cuff and recheck in contralateral arm.
What is the definition of malignant hypertension
Systolic >180 or
Diastolic >120
where do you do a nerve block for the deep peroneal nerve
Lateral to the Extensor hallucis longus tendon
where do you do a nerve block for the sole of the foot.
you inject the tibial nerve the medial malleolus and the achilles tendon.
where do you inject to numb the little toe?
the sural nerve inject between the lateral malleolus and the achilles tendon.
where do you inject for the saphenous nerve (medial foot) and the superficial peroneal nerve (top of foot)
superficial injections at the foot ankle junction crossing from malleolus k
What is the drug of choice for pregnant women
Lidocaine without epi
what two endocrine medical conditions should you not give lidocaine mixed with epinephrine?
Pheochromocytoma
Hyperthyroidism both conditions may have a greater epinephrine sensitivity
What pregnancy class is lidocaine with epi.
with epi class C Lidocaine by itself class B
If lidocaine with epi is normally a 1:200,000 what can it be diluted to in kids?
1:400,000
gold handles on needle drivers usually indicate what?
tungsten carbide inserts.
what should a needle driver be able to grip without slippage if it is working properly.
A hair on the back of your hand.
what margins should be used with a regular excision (non Mohs)of a well defined BCC?
4mm
What is the mechanism of local anesthetics.
anesthetics are Cations (+ charged ions) thatPrevents depolarization by blocking influx of sodium into cells
why are inflammatory sites more difficult to numb up?
Inflammatory response reduces pH which makes the anesthetic in a more non-ionic form with less absorption. High pH makes the aesthetic more lipophilic and better absorbed.
what determines the the onset and duration of action of an anesthetic
(the amine group) hydrophilic
where does the amine group bind?
nerve cell sodium channel pores
what determines the potency of an anesthetic?
the aromatic ring which is lipophilic and determines how much diffuses through the cell membrane.
Why are ester anesthetics unstable in solution?
they are hydrolyzed in plasma by pseudocholinesterase
How are amide anesthetics metabolized
in the liver by enzymatic degradation using cytochrome P450
1% of lidocaine contains how many milligrams of lidocaine per mL
10mg
What is the maximum dose recommended of lidocaine in dermatologic procedures.
500mg or 50ml (1% Lidocaine)
A tacking stitch is also known as what and what does it tack to?
A suspension stitch. Tacks to periosteum or perichondrium
Potency in an injectable anesthetic is directly proportional to what?
lipid solubility
what affects the speed of onset in an anesthetic?
pKa is inversely proportional to speed of onset.
pKa ideal is 50% non ionic 50% ionic, non ionic penetrates better so the higer pKa the more ionic and slower onset of action.
what effects duration of an anesthetic?
Protein binding capacity is directly proportional to duration.
If you apply what over surgical markings it will tend to preserve the marking when wiped with hibiclens or alcohol.
Povidone Iodine
At what level should a biopsy be taken for infiltrative malignancies.
Down into the reticular dermis.
which has greater diagnostic accuracy in bcc shave or punch.
neither both have the same as long as biopsy depth is appropriate. If the tumor appears invasive then reticular dermis should be included.
what does the american heart association consider skin surgery as what risk and what are there recommendations. Low, Intermediate or High
low risk, no recommendations for low risk procedures.
an SCC with cranial bone involvement has a positive needle bx of a node for SCC. What is the next step?
PET-CT scan
What lesion on the lip of a woman that looks like a sclerosing BCC may be difficult to diagnose with a superficial biopsy.
It is hard to tell a desmoplastic trichoepithelioma which is superficial from a Microcystic adnexal carcinoma which goes deep.
What is the average adequate freeze thaw time for AKs, Seb Kers, solar lentigo etc.
5-7 seconds
What are major risk factors for wound dehiscence
smoking BMI >35 Diabetes >65 Infection Extended duration of surgery Emergency surgery peri-operative hypothermia
what is the longest acting injectable anesthetic
Liposomal bupivacaine (Exparel) 72 hours
how much epinephrine is in Liposomal bupivacaine
none
What patients should not get injected with Liposomal bupivacaine
cardiac patients
What should be done before injecting Liposomal bupivacaine
Inject lidocaine 20 minutes before.
maximum vasoconstriction occurs in how many minutes after injection of lidocaine and in how many minutes do you have optium visualization during the skin surgery.
10 minutes
25 minutes
excising a high risk scc what margin gives 95% clearance
6mm
In ester anesthetics name a preservative that can cause allergic reactions.
sodium metabisulfite (sometimes methylparaben)
