Hyperkalemia - a condition in which the concentration of electrolytes, potassium (K +) in the blood rises to dangerous levels of human life. Hyperkalemia patient requiring urgent medical attention due to the potential risk of cardiac arrest at untimely treatment.
The normal level of potassium in the blood is between 3 and 5 5, 0 mEq / L, about 98% of the potassium contained within the cell, and the remaining 2% in the extracellular fluid, including blood and.
Potassium is the most abundant intracellular cation, which is important for many physiological processes, including, for maintaining the resting membrane potential, cell volume homeostasis and transmission of action potentials in nerve cells. Its main dietary sources are vegetables (tomatoes and potatoes), fruits (oranges and bananas) and meat. Potassium excretion takes place through the gastro-intestinal tract, the kidneys and sweat glands.
Hyperkalemia develops when excessive consumption or inefficient excretion of potassium. The increase in extracellular potassium level leads to the depolarization of the membrane potential of the cells due to increased potassium equilibrium potential. Depolarization results in a voltage-gated sodium channels, opens them, and also increases their inactivation, which ultimately leads to ventricular fibrillation or asystole. Prevention of relapse of hyperkalemia usually involves a reduction of food consumption of potassium and potassium-sparing diuretics.
Symptoms of hyperkalemia
Symptoms of hyperkalemia are usually non-specific and include:
- The advent of high T-waves on the electrocardiogram;
- Ventricular tachycardia;
- Muscle weakness;
- Increasing the interval on an electrocardiogram ORS;
- The increase in the PR interval on the ECG.
Also, symptoms of hyperkalemia is cardiac arrhythmia, acute T-wave on an electrocardiogram and excess potassium level greater than 7, 0 mmol / L.
Causes of hyperkalemia
The causes of hyperkalemia may be inefficient elimination of kidney failure, Addison's disease and a lack of aldosterone. It also can cause hyperkalemia reception:
- Angiotensin converting enzyme inhibitors and angiotensin receptor blockers;
- Potassium-sparing diuretics (amiloride, spironolactone);
- Nonsteroidal anti-inflammatory drugs such as ibuprofen, naproxen or celecoxib;
- Calcineurin inhibitors;
- Immunosuppressive drugs (cyclosporine and tacrolimus);
- Antibiotics (trimethoprim);
- Antiparasitic drug pentamidine.
Also cause hyperkalemia can be congenital adrenal hyperplasia syndrome Gordon and renal tubular acidosis type IV.
It can cause hyperkalemia supplementation containing potassium chloride, potassium infusion, and excessive consumption of potassium-containing salt.
Diagnosis of hyperkalemia
To gather sufficient information for the diagnosis of hyperkalemia must constantly measure the level of potassium, since its high state may be related to hemolysis in the first stage. Normal serum potassium is from 3 5 to 5 mEq / L. Usually, diagnosis involves blood tests for kidney function (creatinine, blood urea nitrogen), glucose, and sometimes on the creatine kinase and cortisol. Calculation of the trans-tubular potassium gradient sometimes helps to determine the cause of hyperkalemia, and ECG is performed to determine the risk of cardiac arrhythmias.
Treatment of hyperkalemia
The choice of treatment depends on the extent and causes hyperkalemia. When the content of potassium in the blood exceeds 6, 5 mmol / l urgent need to lower the level of the normal content of potassium. This can be achieved by the introduction of calcium (calcium chloride or calcium gluconate), which increases the threshold potential and restores the normal gradient between the threshold potential and the resting membrane potential, which increases with abnormal hyperkalemia. One ampoule of calcium chloride contains approximately three times more calcium than calcium gluconate. Acting calcium chloride begins in less than five minutes and its effect lasts for about 30-60 minutes. The dosage should be adjusted for constant monitoring of ECG changes during administration and the dose should be repeated if the ECG changes are not normalized within 3-5 minutes.
Also for treatment of hyperkalemia and reduce the risk of complications is possible to conduct some medical procedures that for some time to help stop the process of hyperkalemia as potassium will not be removed from the body. These include:
- Intravenous administration of 10-15 units of insulin together with 50 ml of 50% dextrose to prevent hyperkalemia leads to a shift of potassium ions into the cells. Its effect lasts for a few hours, so that sometimes it is necessary at the same time to take other measures to suppress the potassium level on a more permanent basis. Insulin is generally administered with an appropriate amount of glucose to prevent hypoglycaemia after administration of insulin;
- Bicarbonate therapy (infusion 1 ampoule (50 meq) over 5 min) is an effective method from the displacement of potassium into the cells. Bicarbonate ions stimulate exchange H + for Na +, which leads to stimulation of sodium-potassium ATPase;
- The introduction of salbutamol (albuterol, Ventolin), β 2-selective catecholamine 10-20 mg. This drug also reduces the K +, accelerating its advancement into the cells.
Treatment of severe hyperkalemia requiring hemodialysis or hemofiltration, which are the fastest methods for removing potassium from the body. They are usually used in cases where the primary cause of hyperkalemia can not be fixed quickly or no response to other measures taken.
Sodium polystyrenesulfonate sorbitol orally or rectally widely used to reduce the potassium for several hours and used for furosemide, potassium excretion in the urine.