[HSF] Persistant Hyperkalemia

[prasannasimha]

Double valve replacement with Tricuspid annuloplasty done 2 days back. 
Uneventful post op and extubated on 5 mics of dobutamine and dopamine.
Started getting hyperkalemia since today 3 AM. No clinical or 
biochemical evidence of low output/hemolysis. Urine clear.Echo normal - 
no evidence of paravalvar leak . Lactate 2.7 mmol. Creat 1.5 mg/dL and 
BUN 43 mg/dL
Initially manged hyperkalemia with Lasix , Calcium , glucose Insulin 
Alkalinizaation K binding resin etc but K went upto 6.8 so started 
PDtoday mrning. K+ dropped to 5.1 but now despite good extraction on PD 
, good urine etc last K+ just done now is 6.0. Cannot identify the cause 
of such persistant hyperkalemia. I have removed all nephrotoxic drugs. 
No additional K + sources and I have specifically asked K free diet.
Any ideas/suggestions.
Prasanna