Fencl–Stewart approach: Quantitative Acid-Base Analysis(Strong Ion Difference Changes)

Kiki MK Samsi, dr.,Sp.A, M.Kes

Pediatric Critical Care UnitSumber Waras Hospital

There are three general mechanisms by which SID changes:

changing the water content of plasma (contraction alkalosis and dilutional acidosis)

changing the Cl- (hyperchloremic acidosis and hypochloremic alkalosis),

increasing the concentration of unidentified anions (organic acidosis).

30

Dilutional Acidosis

2 liter

15

WATER

Changing The Water Content Of Plasma

Changing The Water Content Of Plasma

3015

Hyperchloremic acidosis resulting from NS

Changing The Water Content Of Plasma

Changing The Water Content Of Plasma

Normal acid-base following LR

Changing The Water Content Of Plasma

30

Contraction Alkalosis

Changing The Water Content Of Plasma

DIURETIKx

Changing the Cl-

Seorang anak 2 thn, BB 10 kg: Ileus obstruktif Muntah-muntah Dehidrasi berat pH 7.6, Kalium 2 meq/L, Cl 82 meq/L

Tatalaksana Pasang NGT untuk DEKOMPRESI Resusitasi cairan dengan RL Beri KCl untuk hipokalemia

Changing the Cl-

58

Na+ = 140 mEq/LCl- = 82 mEq/L

SID = 58 mEq/LOH- = 58 mEq/L

Hypocloremic Alkalosis

The adverse effects of a severe alkalosis

Decreased myocardial contractility Arrhythmias Decreased cerebral blood flow Confusion Mental obtundation Neuromuscular excitability Impaired peripheral oxygen

unloading (due shift of oxygen dissociation curve to left).

The adverse effects of a severe alkalosis

Hypoventilation (due respiratory response to metabolic alkalosis)

Pulmonary microatelectasis (consequent on hypoventilation)

Increased ventilation-perfusion mismatch (as alkalosis inhibits hypoxic pulmonary vasoconstriction).

Na+ = 140 mEq/LCl- = 82 mEq/L

SID = 58 mEq/LOH- = 58 mEq/L

+

Hypocloremic Acidosis

Na+ = 137 mEq/LCl- = 109 mEq/LLactat = 28 mEq/L

SID = 0 mEq/LOH- = 0 mEq/L

Ringer Lactat

Na+ = (140 + 137 mEq/L) : 2 = 138,5 mEq/L Cl- = ( 82 + 109 mEq/L) : 2 = 95,5 mEq/L

SID = 43 mEq/LOH- = 43 mEq/L

5843

Na+ = 140 mEq/LCl- = 95 mEq/L

SID = 45 mEq/LOH- = 45 mEq/L

+

Hypocloremic Acidosis

Na+ = 154 mEq/LCl- = 154 mEq/L

SID = 0 mEq/LOH- = 0 mEq/L

NaCl 0,9%

Na+ = (140 + 154 mEq/L) : 2 = 147 mEq/L Cl- = ( 82 + 154 mEq/L) : 2 = 118 mEq/L

SID = 29 mEq/LOH- = 29 mEq/L

5829

Treatment of the elevated Cl- and decreased SID would be done by increasing the SID. This could be accomplished through sodium bicarbonate administration. Other ways of administering Na+ with a metabolizable anion are through the use of the sodium salts of lactate, gluconate, acetate or citrate.