Local Anesthesia/ Nail Bed Injuries Flashcards
Why local anesthesia
Increased pt comfort and satisfaction Steady field to work in Easier to clean and remodel wound -Some wounds need to be trimmed more to make it aesthetically pleasing May help keep blood out of field Improved pain control after procedure PTS EXPECT IT
Why NOT local anesthesia?
Increased risk of infection
Toxicity concerns
Allergy concerns
May increase amt of blood in field
It hurts
-Medicine can burn, poke with initial injection
-Will it take longer and cause more pain to anesthetize?
Local anesthesia physiology
Reversibly block conduction of nerve fibers
Prevent increase of permeability of nerve cell membranes to Na+ ions, decreasing rate of depolarization
-Bind intracellular receptor on Na+ channel- inhibit influx
-Does not change resting or threshold potential
Esters
Cocaine Procaine (Novocaine) Tetracaine (Pontocaine) Chloroprocaine Benzocaine Not used much anymore except tetracaine in ophthalmology Do not use tetracaine in open wounds Benzocaine can be found in OTC topical preparations
Order of blockade in anesthesia
Pain Cold Warmth Touch Deep pressure Motor Recovery occurs in reverse order
Duration of cocaine
Med
Max dosage of cocaine
N/A
Duration of procaine
Short
Max dosage of procaine
7 mg/kg
Duration of tetracaine
N/A
Max dosage of tetracaine
N/A
Duration of benzocaine
N/A
Max dosage of benzocaine
N/A
Duration of chloroprocaine
Short (15-30 mins)
Max dosage of chloroprocaine
800 mg; 1000 mg
Duration of lidocaine
Med (30-60 min)
Max dosage of lidocaine
4.5 mg/kg; 7 mg/kg
Duration of bupivacaine
Long (120-240 mins)
Max dosage of bupivacaine
2.5 mg/kg (with epi)
Duration of mepivicaine
Med (45-90 min)
Max dosage of mepivicaine
7 mg/kg to max of 400
Duration of etidocaine
Long (120-180 min)
Max dosage of etidocaine
6 mg/kg; 8 mg/kg
Duration of prilocaine
Med (30-90 min)
Max dosage of prilocaine
500 mg; 600 mg
Central nervous system toxicity of anesthesia: initial sx
Perioral tingling/numbness Metallic taste Lightheaded/dizzy Visual/auditory hallucinations -Tinnitus, difficulty focusing Disorientation/drowsiness Instruct pts before you start so they can let you know during the procedure
CNS toxicity in higher doses
Muscle twitching Convulsions Unconsciousness/coma Respiratory depression/arrest CV depression/collapse
Direct cardiac effects of anesthesia
Myocardial depression (tetracaine, etidocaine, bupivacaine) Cardiac dysrhythmias (bupivacaine) Cardiotoxicity in pregnancy? (may be based on bat rat studies)
Peripheral CV effects of anesthesia
Vasodilate at low doses
Vasoconstrict at higher doses
Range of CV effects
CP SOB Palpitations Lightheadedness Diaphoresis Hypotension Syncope
Hematological toxicity
Metabolite of procaine (also seen with lidocaine and benzocaine) oxydizes hemoglobin to methemoglobin -Methemoglobin is same substance found in carbon monoxide poisoning Cyanosis Cutaneous discoloration (gray) Tachypnea/dyspnea Exercise intolerance/fatigue Dizziness and syncope Weakness
Lidocaine
Rapid onset (1-2 mins to peak)
Relatively short duration of action (~1 hr)
Acidic, so burns briefly on injection
-Can buffer (10:1 lido: sodium bicarb)
- Bicarb causes anesthesia to be taken up more quickly
Lidocaine concentrations
1% -Most commonly used 2% -Allows you to use less medicine (small spaces) -Sometimes used for nerve blocks -Good for ears and peds Both come with and without epi
Lidocaine with epi
Helps limit bleeding in field
Slows the rate of medication washout from field
Lidocaine without epi
NEVER inject epi into distal appendages
-Ears, nose, fingers, toes, penis
If you inject epi by mistake, use nitro paste
Bupivacaine
0.25%, 0.5%; with and without epi
Slower onset (5-10 mins to peak)
Longer acting (~4 hrs and up)
Commonly used for nerve blocks
Sometimes mixed with lidocaine to provide rapid onset with longer duration
Has been shown to reduce residual pain, even after it has worn off
Topical anesthetics
LET/LAT, EMLA cream
-EMLA cream is combo of lidocaine/prilocaine
Avoid pain associated with injection
Avoid wound margin distortion
Take time to work (20-45 mins)
May not work as well in older children and adults
Don’t work if not applied properly
How to properly apply topical anesthetics
Tear off a piece of cotton ball enough to cover wound
Completely saturate
Put on wound with tape
Medication choice
Never underestimate the power of distraction, esp in children!
Having a child watch TV works the best
Allergies
Lidocaine and Novocaine are in different classes of anesthetics, so an allergy to Novocaine usually does not indicate an allergy to lidocaine
Lidocaine and bupivacaine are in the same class
Many lidocaine allergies area actually reactions to the preservative in the multi-dose vials
In a pinch, can use non-traditional anesthesia
-Ice or injection with Benadryl or even saline will all provide some degree of anesthesia
Local infiltration
Most commonly used method
quick and simple, easily mastered
Provides immediate anesthesia to localized area
Tends to distort wound margins
Usually requires multiple injections
Can turn localized infection into blood-borne infection
Method- local infiltration- supplies
Use small syringe (no greater than 5 mL)
Use long, thin needle (27 gauge, 1 1/4 inch) except on very small or facial wounds
Draw up more than you’ll need- this may require use of multiple syringes
Orient yourself with the wound so that you can work comfortably
-Try to work with the wound pointing away from you
Method-local infiltration- injection
If injecting through skin, prep area with EtOH
Less painful to insert needle into subcutaneous tissue from inside wound
Try to start on the proximal aspect of wound
Insert needle fully, aspirate to check for blood, and inject SLOWLY as you withdraw the needle
Repeat as needed (both sides of wound) and check for numbness
Field block
Similar to local infiltration, except done few inches away from wound -Avoids wound margin distortion -Avoids injection through infection -Good for ears, abscesses Relatively easy to master infiltrate a perimeter around wound site Field inside perimeter should be numb
What should you avoid in a field block?
Sternocleidomastoid
Digital block
Often performed for pt comfort -Good alternative for pain meds or for procedures other than wound repairs Same benefits as field block Relatively easy to master Uses less medicine -Usually 1-4 mL is all you need Long-acting anesthetic often best After injection, allow 10-15 mins for anesthesia to set up before procedure
Subungual hematoma
Trauma to nail results in bleeding under nail plate
Bleeding separates nail plate from nail bed
Trephination
Use of a small, usually hollow, instrument to make a hole in a solid surface
Preparation for subungual hematoma
Skin prep Trephine -Electrocautery -18g needle or scalpel -Heated paperclip? Anesthesia? Gloves, eye protection
CIs to trephination
Severe crush injury
Underlying fx?
Indications for nail plate removal
Severe crush injury, fracturing plate -If repair needed: 6-0 or 7-0 absorbable monofilament Severe injury with intact plate? Subungual abscess Ingrown nail?
Preparation for nail plate removal
Skin prep
Anesthesia
Hemostats, iris scissors
Gloves, eye protection
Steps for nail plate removal
Use hemostats to lift nail Scissors may be needed to undermine If underlying matrix is destroyed, nail will not grow back -Phenol/alcohol -Electrocautery
