Serum [Na] > max acceptable level

1. Don’t panic, ODS doesn’t happen quickly and you have time to think
2. Continue DDAVP & stop HTS

If Na only slightly > max level → give D5 to bring down Na

1. Simple rule of thumb: 250ml D5 can ↓Na by ~1mmol/L
2. Or you can calculate yourself or with MD Calc
   • 3ml/Kg of D5 = Na↓1mmol/L
3. → if Na still > max level → give more D5
4. → if Na ≤max level → just don’t do anything & wait till 24h period
   • Keep regular DDAVP & No HTS nor other IVF
   • Give time for brain cells to equilibrate

• Review blood taking time: match with change of HTS rate?
• Sort out the reason: input vs output
  1. Input:
     • Drugs with high sodium content e.g. tazocin
     • From other electrolytes e.g. replacing K
  2. Output:
     • DDAVP effect inadequate
       • Hint:
         1. ↑urine output
         2. Low urine osm
       • Cause:
         1. Glycosuria
         2. Urea e.g. high protein intake, steroids, recovery from azotemia
         3. Nephrogenic DI
            • Profound hypoK may downregulate AQP2
              • → correct hypoK but pay attention to its effect on [Na]
            • Other causes unlikely to cause acute NephDI
         4. Delay of DDAVP administration → DDAVP “escape”
         5. DDAVP effect offset by other meds (e.g. lasix given by other teams)
         6. DDAVP dose inadequate
            • Extreme obesity
            • → ↑dose to 2mcg Q4H

If Na >> max level

• r/o the obvious cause e.g. drip arm, blood taking from CVC during HTS infusion from same line
• Otherwise, sort out the reason: Input vs output
  1. Input:
     • ?potential drug administrative error
     • Wrong calculation
     • Wrong HTS rate
  2. Output:
     • HTS started before DDAVP effect kicks in → ↑↑↑renal free water excretion in hypovolaemic  hypoNa / beer potomania / tea & toast syndrome
     • review if someone else has screwed it up already (e.g. given NS+NaCl tab by Medical before ICU admission)
     • → bring down Na with D5 and start all over again