April 27, 2016 - Hyperkalemia Flashcards
Hyperkalemia Scheme
TTKG in Hyperkalemia
TTKG Should be >7 if there is hyperkalemia.
A TTKG of less than 7 indicates that the principal cell is a problem.
Hyper Osmolarity and Hyperkalemia
In the presence of hyperosmolarity, water will leave the cell and bring some of the potassium with it. This can inflate the serum potassium levels.
Cell Lysis and Hyperkalemia
If cells are lysing, they are spilling their contents into the serum which can increase the levels of potassium.
If this is the cause of hyperkalemia, you would also expect to see high levels of phosphate and uric acid as they will spill into the cell too.
Symptoms of Hyperkalemia
Arrythmias in the cardiac muscle / conducting system
Skeletal muscle weakness. You would think that having a resting membrane potential closer to the deactivation threshhold would make it easier to use the muscles, but another mechanism trumps this; the gated sodium channel which causes an influx of sodium during an action potential goes into an active state, making it more difficult to depolarize the cell.
ECG Changes in Hyperkalemia
PR interval prolongation
Increase in T-wave amplitude with ‘peaking’
Flattening or absence of the p-wave
Prolongation of QRS +/- ventricular arrythmais
QRST ‘sine-wave’
* ECG changes are the most helpful signs of hyperkalemia *
Treatment of Hyperkalemia
If life-threatening with ECG changes, you need intravenous calcium, induce an intracellular shift, or increase the elimination.
If non-life threatening, you can address the underlying cause.
Calcium and Potassium
Injecting calcium into the patient can lower high potassium.
