3 pH, pK, Henderson-Hasselbalch, Anion Gap, SID Flashcards
Lidocaine Max Doses
7mg/kg w/ Epi
5mg/kg w/out
Total 500mg
Mepivacaine
7mg/kg w/ Epi
5mg/kg w/out
Total 500mg
Bupivacaine
3mg/kg w/ Epi
2mg/kg w/out
Total 225mg
Ropivacaine
3.5mg/kg w/ Epi
3mg/kg w/out
Total 300mg
Epi Concentrations
1:1,000 (g/ml) = 1mg/ml = 1,000mcg/ml STOCK
1:10,000 = 0.1mg/ml = 100mcg/ml
1:100,000 = 0.01mg/ml = 10mcg/ml
1:200,000 = 0.005mg/ml = 5mcg/ml
1:400,000 = 0.0025mg/ml = 2.5mcg/ml
1:500,000 = 0.002mg/ml = 2mcg/ml
g/ml x 10^6 = mcg/ml
Henderson-Hasselbalch
pH = pK + log(UNprotonated/Protonated) pK = pH + log(Protonated/UNprotonated)
Protonated
Ionized +/-
BH+
A¯ (acid)
H+ donator
UNprotonated
Non-ionized (neutral)
B (base)
HA
H+ acceptor
Logarithmic
Log(a/b) = Log(a) - Log(b)
Log(a/b) = - Log(b/a)
- Log(a/b) = Log(b/a)
Log(a·b) = Log(a) + Log(b)
Log(1) = 0 1x10^0 Log(100) =2 1x10^2 Log(0.1 or 1/10) = -1 1x10-1 Log(0.01 or 1/100) = -2 1x10-2
Plasma Ion Concentration
H+ = 40nmole/L = 4 x 10^-5mEq/L K+ = 4,000,000nmole/L = 4mEq/L Ca2+ = 2,500,000nmole/L = 5mEq/L Mg2+ = 1,000,000nmole/L = 2mEq/L Na+ = 140,000,000nmole/L = 140mEq/L nmole/L (1x10^6) / 1,000,000 x charge +/-
% Protonated/UNprotonated
pK = pH + log(Protonated/UNprotonated)
BH+/B or A¯/AH
Local Anesthetic Onset
↑ non-ionized (unprotonated) = quicker onset time
mEq
nmol / 1,000,000 x charge +/- = mEq
Local Anesthetic MOA
BH+ ↔ B + H+
Conjugate acid ↔ Base + Proton
Non-polar/neutral/base/UNprotonated form to cross lipophilic membrane
Acidic environment ↑ H+ local anesthetic associates to protonated BH+ active form to act on VGNa+ channels from w/in the cell (intracellular action)
pH or H+ concentration impacts direction (association or dissociation)
CO2 Hydration Reaction
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3¯
Carbonic anhydrase enzyme facilitates reaction
