Local Anaesthetic DrugsLocal Anaesthetic DrugsDrug

Brand Name

Maximum Safe Dose Onset Duration pKa

Lidocaine Xylocaine 3mg/kg 2 – 5 mins 1 – 1.5 hrs 7.7

Mepivacaine Scandonest 6mg/kg 2 – 5 mins 1.5 – 2 hrs 7.6

Prilocaine Citanest 6mg/kg 2 – 5 mins 1.5 – 2 hrs 7.7

Bupivocaine Marcain 2mg/kg 15 – 30 mins 4 – 6 hrs 8.1

Levobupivocaine Chirocaine 2mg/kg 10 – 15 mins 4 – 6 hrs + 8.1

Ropivacaine Naropin 4.3mg/kg 10 – 15 mins 4 – 6 hrs + 8.1

Local Anaesthetic DrugsLocal Anaesthetic Drugs Lidocaine with Adrenaline (1:200,000)Lidocaine with Adrenaline (1:200,000)

MSD 7mg/kgMSD 7mg/kg Bupivicaine with Adrenaline (1:200,000)Bupivicaine with Adrenaline (1:200,000)

MSD 2mg/kgMSD 2mg/kg

Local Anaesthetic DrugsLocal Anaesthetic Drugs AdrenalineAdrenaline

Increase MSD (not Bupivicaine)Increase MSD (not Bupivicaine) Reduce rate of absoprptionReduce rate of absoprption Prolong durationProlong duration

Local Anaesthetic DrugsLocal Anaesthetic Drugs

What is pKa ?What is pKa ? pKa is the pH at which the LA drug pKa is the pH at which the LA drug

performs to it’s maximum potentialperforms to it’s maximum potential Normal body tissue pH is 7.4Normal body tissue pH is 7.4

% ionised

pH

8.1

7.77.4

10% 25% 50% 100%

Diagramatic representation of relative ionisation of bupivacaine

and lidocaine

Lidocaine

Bupivacaine

At body pH (7.4)Lidocaine is 25% ionisedBupivacaine is only 10% ionised

Maximum Safe Dose - MSDMaximum Safe Dose - MSD This is maximum dose a drug that should This is maximum dose a drug that should

be given to a patient in a 24 hour periodbe given to a patient in a 24 hour period It is calculated in milligrams per kilogram It is calculated in milligrams per kilogram

(mg/kg)(mg/kg) Based on a maximum body weight of 70kgBased on a maximum body weight of 70kg

MSD - ExamplesMSD - Examples A patient weighs 70 kg. A patient weighs 70 kg. How much Lidocaine can be given?How much Lidocaine can be given? MSD for Lidocaine = 3mg/kgMSD for Lidocaine = 3mg/kg Weight is 70 kgWeight is 70 kg MSD is 3 x 70 = 210 mgMSD is 3 x 70 = 210 mg

MSD - ExamplesMSD - Examples A patient weighs 50 kgA patient weighs 50 kg How much mepivacaine can be given?How much mepivacaine can be given? MSD for mepivacaine = 6 mg/kgMSD for mepivacaine = 6 mg/kg Weight is 50kgWeight is 50kg MSD is 6 x 50 = 300 mgMSD is 6 x 50 = 300 mg

MSD - ExamplesMSD - Examples A patient weighs 97 kgA patient weighs 97 kg How much marcain can be given?How much marcain can be given? MSD for marcain = 2 mg/kgMSD for marcain = 2 mg/kg Work on a maximum body weight of 70 kgWork on a maximum body weight of 70 kg MSD is 2 x 70 = 140 mgMSD is 2 x 70 = 140 mg

Answers 1 - 7Answers 1 - 7 68 x 3 = 204mg68 x 3 = 204mg 37 x 2 = 74mg37 x 2 = 74mg 90 rounded down to 70; 70 x 2 = 140mg90 rounded down to 70; 70 x 2 = 140mg 74 rounded down to 70; 70 x 6 = 420mg74 rounded down to 70; 70 x 6 = 420mg 44 x 3 = 132mg44 x 3 = 132mg False: 140mg is MSDFalse: 140mg is MSD True: MSD is 63 x 6 = 378mgTrue: MSD is 63 x 6 = 378mg

Answers 8 - 10Answers 8 - 10 No. MSD = 70 x 3 = 210. Received 204. No. MSD = 70 x 3 = 210. Received 204.

Another 20mg = 230mgAnother 20mg = 230mg 81 rounded down to 70; MSD = 70 x 6 = 81 rounded down to 70; MSD = 70 x 6 =

420mg. 420 – 132 = 288mg420mg. 420 – 132 = 288mg 85 rounded down to 70; MSD = 70 x 6 = 85 rounded down to 70; MSD = 70 x 6 =

420mg. 420 – 192 = 228mg420mg. 420 – 192 = 228mg

Answer - 11Answer - 11 The MSD of scandonest is 6mg/kgThe MSD of scandonest is 6mg/kg He has received 192mg of scandonestHe has received 192mg of scandonest How many kg of body weight has been How many kg of body weight has been

used – 192/6 = 32used – 192/6 = 32 We still have 38kg left to work with (70 – We still have 38kg left to work with (70 –

32)32) MSD of lidocaine is 3mg/kg thereforeMSD of lidocaine is 3mg/kg therefore 38 x 3 = 114mg38 x 3 = 114mg

Answer 12Answer 12 MSD of Lidicaine is 3mg/kgMSD of Lidicaine is 3mg/kg Received 100mg of lidocaineReceived 100mg of lidocaine How many kg of body weight used; 100/3 How many kg of body weight used; 100/3

= 33.3 – round up to 34kg= 33.3 – round up to 34kg We have 26kg left to work with (Pt is 60kg)We have 26kg left to work with (Pt is 60kg) MSD of chirocaine is 2mg/kgMSD of chirocaine is 2mg/kg 26 x 2 = 52mg26 x 2 = 52mg

Dose CalculationsDose Calculations The dose of local anaesthetic is measured The dose of local anaesthetic is measured

in mgin mg The formula for calculation of dose is;The formula for calculation of dose is;

Dose (mg) = Dose (mg) = volume (ml) x drug concentration (%) x 10volume (ml) x drug concentration (%) x 10

Mg = ml x % x 10Mg = ml x % x 10

Dose CalculationsDose Calculations mg = ml x % x 10mg = ml x % x 10 ml = the volume of solution usedml = the volume of solution used % = will be displayed on vial% = will be displayed on vial

Dose Calculations - ExampleDose Calculations - Example I use 4mls of 1% lidocaine to anaethsetise I use 4mls of 1% lidocaine to anaethsetise

a digit. What dose have I given?a digit. What dose have I given? Formula is;Formula is;

Dose = volume x concentration x 10Dose = volume x concentration x 10 Mg = ml x % x 10Mg = ml x % x 10 Mg = 4 x 1 x 10Mg = 4 x 1 x 10 Dose = 40mgDose = 40mg

Volume calculationsVolume calculations I use 40mg of 1% lidocaine. How many I use 40mg of 1% lidocaine. How many

mls did I inject?mls did I inject? Ml = dose (mg) / Concentration (1%) / 10Ml = dose (mg) / Concentration (1%) / 10 Ml = 40 / 1 / 10Ml = 40 / 1 / 10 Ml = 4Ml = 4 I used 4 mlI used 4 ml

Answers to calculate mgAnswers to calculate mg 6 x 2 x 10 = 120mg6 x 2 x 10 = 120mg 4 x 0.5 x 10 = 20mg4 x 0.5 x 10 = 20mg 4.4 x 3 x 10 = 132mg4.4 x 3 x 10 = 132mg 12 x .25 x 10 = 30mg12 x .25 x 10 = 30mg 0.8 x 3 x 10 = 24mg0.8 x 3 x 10 = 24mg 5 x 1 x 10 = 50mg5 x 1 x 10 = 50mg 3.7 x 3 x 10 = 111mg3.7 x 3 x 10 = 111mg 8.3 x 2 x 10 = 166mg8.3 x 2 x 10 = 166mg

Answers to calculate ml Answers to calculate ml 20 / 1 / 10 = 2mls20 / 1 / 10 = 2mls 120 / 3 / 10 = 4mls120 / 3 / 10 = 4mls 35 / 2 / 10 = 1.75mls35 / 2 / 10 = 1.75mls 15 / 0.5 / 10 = 3mls15 / 0.5 / 10 = 3mls 66 / 3 / 10 = 2.2mls66 / 3 / 10 = 2.2mls

Answer to calculate mlsAnswer to calculate mls MSD = 210mg for lidocaineMSD = 210mg for lidocaine

210 / 1 / 10 = 21mls210 / 1 / 10 = 21mls 210 / 2 / 10 = 10.5mls210 / 2 / 10 = 10.5mls

MSD = 420mg for mepivicaineMSD = 420mg for mepivicaine 420 / 3 / 10 = 14mls420 / 3 / 10 = 14mls

MSD = 140mg for marcain and chirocaineMSD = 140mg for marcain and chirocaine 140 / 0.25 / 10 = 56mls140 / 0.25 / 10 = 56mls 140 / 0.5 / 10 = 28mls140 / 0.5 / 10 = 28mls

ImportantImportant Do not mix Local Anaesthetic Drugs in Do not mix Local Anaesthetic Drugs in

same syringesame syringe

Podiatric Uses of Local Podiatric Uses of Local AnalgesiaAnalgesia

Surface LA – painful HNVSurface LA – painful HNV Regional Infiltration – painful HNVRegional Infiltration – painful HNV

Podiatric Uses of Local Podiatric Uses of Local AnalgesiaAnalgesia

Para-digital nerveblockPara-digital nerveblock TNA/PNA; Wedge resections; HNV on IPJ’sTNA/PNA; Wedge resections; HNV on IPJ’s

Tibial blockTibial block Electrosurgery; VP curettage; Plantar HNV; Electrosurgery; VP curettage; Plantar HNV;

Precurser to injection therapies; Precurser to injection therapies; Dermatological biopsiesDermatological biopsies

11stst Ray block Ray block Electrosurgery; VP curettage; 1Electrosurgery; VP curettage; 1stst MTPJ HNV MTPJ HNV

Podiatric uses of Local Podiatric uses of Local AnalgesiaAnalgesia

Diagnostic AidDiagnostic Aid Plantar digital neuritisPlantar digital neuritis Tarsal tunnel syndromeTarsal tunnel syndrome

Therapeutic AidTherapeutic Aid Rheumatoid ArthritisRheumatoid Arthritis UlcerationUlceration

Chronic Pain ReliefChronic Pain Relief Plantar FasciitisPlantar Fasciitis

Podiatric Uses of Local Podiatric Uses of Local AnaelgesiaAnaelgesia

In conjunction with corticosteroid injectionIn conjunction with corticosteroid injection(do not mix)(do not mix)

Tibial NerveTibial Nerve

Superficial and Deep Superficial and Deep Peroneal NervesPeroneal Nerves

Sural NerveSural Nerve

Saphenous NerveSaphenous Nerve