Quen Mok Great Ormond Street Hospital

Chloride: Queen of electrolytes?

Predominantly excreted by the kidneys 99% reabsorbed 60% passively in proximal tubules following active sodium transport 15-25% in loop of Henle 5% in distal tubule - aldosterone Renal handling of Chloride

Renal excretion of Chloride

Hyperchloremic acidosis So why is hyperchloremia a problem? Immune activation and pro-inflammatory Renal dysfunction – renal vasoconstriction and decreased GFR Clotting abnormalities Increased mortality

Hyperchloremic acidosis Infusions of 0.9% Saline and Plasmalyte on renal blood flow velocity and renal cortical tissue perfusion Chowdhury AH et al Ann Surg 2012;256:18-24

Chloride rich solutions Serum chloride mmol/l 0.9% saline – 154 mmol/l chloride 4.5% Albumin – up to 160 mmol/l chloride Hence large volumes potentiate metabolic acidosis regardless of the underlying disease process Often unrecognised and poorly managed Misdiagnosed as inadequate perfusion Base deficit used as a key prognostic variable in paediatric mortality risk score

Stewart approach Plasma pH determined by Strong ion difference (SID) – difference between strong cations (Na, K, Ca, Mg) and strong anions (Cl and lactate) PaCO2 Weak acids (A tot ) – mainly albumin and inorganic phosphate Decreased SID has acidifying effect as changes degree of water dissociation into hydrogen ions

Strong ion difference

Electrolyte composition of common IV fluids CationsAnionsOsm NaKCaMgClAcetateLactateGluconatemosmol /l Plasma Bicarbonate NaCl1540 Ringer lactate Ringer acetate Hartmann ’s Plasma- lyte

Dialysis Replacement solutions All contain high chloride levels ( mmol/l) Lower if potassium free bicarbonate solutions Serum electrolytes equilibrate with replacement fluid

Chloride is a major strong anion in the extracellular fluid space Hyperchloremic acidosis causes renal vasoconstriction and decreased GFR May be misinterpreted as inadequate tissue perfusion Consider use of balanced solutions Serum electrolyte equilibrate with dialysis replacement fluid Conclusions

Not the case with chloride…….