Question

A veterinarian ordered a liter of Hartmann’s Irrigation (lactated Ringer’s irrigation) with the following formula:

(25 points)

Sodium chloride 600 mg

Sodium lactate 310 mg

Potassium chloride 30 mg

Calcium chloride, dihydrate 20 mg

Water for injection, ad 100 mL

Calculate the mOsmol/L of Na+, K+, Ca2+, Cl−, and C3H5O3−.

Answer 1

Formula for calculating mOsmol/L

mOsmol/L = [wt of substance (g/L) / Molecular Weight (g)] x number of species x 1000

Number of species indicated the number of particles in a substance.

Given

• Sodium chloride 600mg = 0.6g [1g= 1000mg]
• Sodium lactate 310mg = 0.31g
• Potassium chloride= 30mg= 0.03g
• Calcium chloride,dihydrate 20mg = 0.02g

Sodium chloride (Nacl)

Na= [ 0.6 /23] x 2 x 1000

= 52.17 mOsmol/L

Cl = [0.6/35.5] x2x1000

= 33.80 mOsmol/L

Sodium lactate (NaC3H5O3)

Number species = 1+3+5+3=14

Na = [0.31/23]x14x1000

= 188.69 mOsmol/L

C3H5O3 molecular weight= 89.07

C3H5O3 = [0.31/ 89.07] x14x1000

= 48.73 mOsmol/L

Potassium chloride (KCl)

K = [0.03/89.07] x 2x1000

= 0.67 mOsmol/L

Cl =[0.03/35.5] x2x1000

= 1.69 mOsmol/L

Calcium chloride, dihydrate (CaCl2H4O2)

Number of species = 1+2+4+2=9

Ca =[0.02/40] x9x1000

= 4.5 mOsmol/L

Cl = [0.02/35.5] x9x1000

= 5.07mOsmol/L

Cl2 = 2x 5.07 =10.14 mOsmol/L

Therefore Na = 240.86mOsmol/L (52.17+188.69)

Cl = 45.63 mOsmol/L

C3H5O3=48.73 mOsmol/L

K   = 0.67 mOsmol/L

Ca = 4.5 mOsmol/L

Refer this table for molecular weight