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Toronto Notes 2019 Post-Operative Care Systemic Toxicity
• seeTable14formaximumdoses,potency,anddurationofactionforcommonLAagents
• occursbyaccidentalintravascularinjection,LAoverdose,orunexpectedlyrapidabsorption
CNS Effects
• CNSeffectsfirstappeartobeexcitatoryduetoinitialblockofinhibitoryfibres,thensubsequentblock of excitatory fibres
• effectsinorderofappearance
■ numbness of tongue, perioral tingling, metallic taste ■ disorientation, drowsiness
■ tinnitus
■ visual disturbances
■ muscle twitching, tremors
■ unconsciousness
■ convulsions, seizures
■ generalized CNS depression, coma, respiratory arrest
CVS Effects
• vasodilation, hypotension
• decreasedmyocardialcontractility
• dose-dependentdelayincardiacimpulsetransmission
■ prolonged PR, QRS intervals
■ sinus bradycardia • CVScollapse
Treatment of Systemic Toxicity
• earlyrecognitionofsigns,gethelp
• 100%O2,manageABCs
• diazepamorotheranticonvulsanttopreventpotentialonsetofseizures • managearrhythmias(seeAppendices,A30)
• Intralipid®20%tobindlocalanestheticincirculation
Local Infiltration and Hematoma Blocks
Local Infiltration
• injectionoftissuewithLA,producingalackofsensationintheinfiltratedareaduetoLAactingonnerves • suitableforsmallincisions,suturing,excisingsmalllesions
• canusefairlylargevolumesofdiluteLAtoinfiltratealargearea
• lowconcentrationsofepinephrine(1:100,000-1:200,000)causevasoconstriction,thusreducingbleeding
and prolonging the effects of LA by reducing systemic absorption
Fracture Hematoma Block
• specialtypeoflocalinfiltrationforpaincontrolduringmanipulationofcertainfractures • hematomacreatedbyfractureisinfiltratedwithLAtoanesthetizesurroundingtissues
• sensoryblockademayonlybepartial
• nomusclerelaxation
Topical Anesthetics
• variouspreparationsoflocalanestheticsavailablefortopicaluse,maybeamixtureofagents(EMLA cream is a combination of 2.5% lidocaine and prilocaine)
• mustbeabletopenetratetheskinormucousmembrane
Post-Operative Care
• painmanagementshouldbecontinuousfromORtopost-anestheticcareunit(PACU)tohospitalward and home
Common Post-Operative Anesthetic Complications
Uncontrolled/Poorly Controlled Pain
Nausea and Vomiting
• hypotensionandbradycardiamustberuledout
• painandsurgicalmanipulationalsocausenausea
• oftentreatedwithdimenhydrinate(Gravol®),metoclopramide(Maxeran®;notwithbowelobstruction),
Anesthesia A23
Cardiovascularcollapse Respiratory arrest
Coma Convulsions Unconsciousness
Muscle twitching
Sensory abnormalities (i.e. visual disturbances,
Lightheadedness tinnitus) Tongue numbness
Figure 13. Local anesthetic systemic toxicity
Where Not to Use LA with Epinephrine
“Ears, Fingers, Toes, Penis, Nose”
prochlorperazine (Stemetil®), ondansetron (Zofran®), granisetron (Kytril®)
[Local anesthetic]