Hyperkalaemia - is raising the concentration of potassium ions in human blood levels above 5 mmol / l.The cause of hyperkalemia may be either the output of potassium ions from the intracellular space outside, or violation of its excretion excretory system, particularly the kidneys.Sometimes it can cause dehydration or use excessive amounts of potassium intake with drugs that contain potassium.
identify hyperkalemia possible using electrocardiography, as the high content of potassium manifests itself a violation of the priority work of the myocardium.Also, high concentrations of potassium can cause generalized muscle weakness.Hyperkalemia is adjusted on the basis of laboratory values and taking into account changes in the patient's condition.
Causes of hyperkalemia
To understand the causes of hyperkalemia should be understood, taken from the potassium in the body, in which metabolic processes involved, and how to then output therefrom.
it is known that all the component
primary role in ensuring continuous permanent balance of minerals in the blood given to the excretory system.Kidneys, operation of which is regulated by hormones - aldosterone, vasopressin and atrial natriuretic hormone, exercise excretion of excessive amounts of minerals (including potassium) or, alternatively, promote their retention in the body.Due to the large reserves
potassium inside the cells, maintaining constant its level in plasma is not particularly affected by changes in the water balance, because only 2% of the potassium that is contained in the body is outside the cell.The main part, about 85% of potassium excreted in the urine, largely because maintaining its quantity in the body is dependent on the proper functioning of the kidneys.
primary part potassium normally reabsorbed in the proximal tubule and the loop of Henle of primary urine, and in the distal potassium ions are secreted in exchange for sodium ions.It is the latter of the above mechanisms regulated by aldosterone.In general, hyperkalemia effectively prevented by renal regulation mechanism, under normal operation.
Hyperkalemia due nephrology pathology develops with diseases such as acute or chronic renal failure (if oliguria) and giporeninemichesky hypoaldosteronism and Addison's disease.Thus, renal insufficiency, by itself, does not cause hyperkalemia until glomerular filtration rate drops 15-10 ml / min.Alternatively, the total number of allocated urine per day is less than 1 liter.
Besides diseases disrupt the functioning of the renal mechanism could drugs that interfere with potassium excretion by the kidneys (eg - heparin, ACE inhibitors, amiloride, spironolactone and others), thereby developing hyperkalemia.
For example, spironolactone and other diuretics from his group, have an effect similar to aldosterone inhibitors.By connecting to the receptor, they prevent further connections to the same aldosterone receptor.Thus inhibited aldosterone-dependent sodium reabsorption in the cortical collecting ducts of the department, and at the same time slowing down the distal tubular secretion of potassium.All of them act by different mechanisms, but can cause the development of hyperkalemia, and therefore they should be used with caution in patients with renal failure or diabetes.
Hyperkalemia can be caused not only by nephrological problems, but also other diseases and conditions.This may be because an excessive intake of potassium from the outside (including iatrogenic causes) gipoaldosteronizm, insulin deficiency, hyperosmolarity blood acidosis disease with genetic predisposition (Pseudohypoaldosteronism type II giperkaliemichesky periodic paralysis).Also, the probable cause may be taking medication without nephrotoxic effects, but increase the level of potassium in the blood, among them - digitalis drugs, beta-blockers, arginine hydrochloride.
Symptoms and signs of hyperkalemia
Potassium in excess causes changes in cell membrane potential, which is manifested general muscle weakness, apathy, weakening of tendon reflexes.When reaching severe hyperkalemia, it may essentially be broken neuromuscular transmission, until the development of paralysis (including the paralysis of respiratory muscles and the diaphragm, and hence the appearance of respiratory distress).
depolarization of the cells and the potential change is also particularly significant and noticeable in cardiomyocytes.Reduced excitability of heart muscle cells hinders nerve impulse conduction system in the heart and direct impact on the work of the heart muscle.
Cardiotoxicity high concentrations of potassium can trigger a variety of cardiac arrhythmias, by minor changes in the electrocardiogram, to supraventricular beats, atrio-ventricular dissociation, sinoatrial blockade, and in severe cases, clinical and ventricular fibrillation with and / or asystole.
diagnosis of hyperkalemia
All of the above changes can be detected easily with the help of an electrocardiogram.Hyperkalemia ECG has a very characteristic features.The most informative diagnostic leads, especially in the early stages, with a slight increase in potassium levels is narrowing and sharpening tooth tip T.
first signs that appear when hyperkalemia is extended upward, above the normal height of the T wave, which indicates problems with the repolarizationheart muscle.Furthermore conduction disturbances begins to manifest extension segment P-R, indicating a slowing of the atrio-ventricular transmission, as well as the expansion of the ventricular complex - QRS, that signals a slowing of the pulse of ventricular myocardium.
With further increase of hyperkalemia, without a correction and relief, gradually disappearing P wave is developing ventricular tachycardia, ventricular fibrillation, asystole up to.According to some cardiac arrest causes the concentration of potassium in the 7.5-10 mmol / L.
Despite the fact that hyperkalemia ECG has a very informative for the diagnosis and often do not cause difficulties with its formulation of an experienced clinician, it is necessary to clarify the level of increase in potassium laboratory.In carrying out biochemical analysis of blood, an accurate, detailed information about the level of potassium in blood serum or plasma.Normal parameters - it is 3,5-5,3 mmol / L, while raising the level of potassium to the mark of 5.5 mmol / l can confidently say hyperkalemia, which is to begin treatment within the first hour after the diagnosis of this condition.
treatment of hyperkalemia
hyperkalemia Treatment should be aimed at the normalization of the level of potassium in the blood and eliminate symptoms caused by hyperkalemia.
with a slight increase in potassium levels, up to 6 mmol / l, sufficient to cancel medications that increase potassium levels (eg beta-blockers, potassium-sparing diuretics, ACE inhibitors and others).
also effective in this case is when the diet of hyperkalemia, which includes limiting foods high in potassium compounds.
effective is the application of different laxatives and enemas, to accelerate the elimination of potassium in the feces through the gastrointestinal tract.The drug of choice in such a situation to select appropriate Sorbitol (polystyrene sulfonate).Using it is carried out the so-called cation-exchange treatment, which, unfortunately, is not as effective on the reduction of the concentration of potassium ions in the plasma, in advanced stages pathogenetic processes in more severe cases.
is appropriate to add the patient to the treatment regimen loop diuretic, provided that renal function is not critically impaired, and thus increase the excretion of potassium through the kidneys.
If hyperkalemia more pronounced, and the potassium level greater than 6 mmol / l, in such a case requires determined action and a set of measures aimed at reducing the income of potassium in the body and its urgent removal from plasma.
To effectively reduce the level of potassium in the plasma, it is necessary to operate in two directions - assist its movement into the cells and removing it out from the body.
When there are disturbances of cardiac rhythm, use a 10% solution of calcium gluconate is administered it intravenously 10-20 ml for 15-20 minutes.Precautions should use it if the patient received in the recent time cardiac glycosides (digitalis preparations).Calcium gluconate improves the electrocardiogram, but does not reduce the concentration of potassium in the blood, respectively, does not affect causal.
In case of acidosis, under the control of blood pH, intravenously sodium hydrogencarbonate (sodium bicarbonate) at a dose of 44 mEq.
For these purposes are sometimes administered calcium chloride, in the event that central venous catheter, since calcium chloride is a strong irritant and can cause inflammation of the walls of the blood vessels (phlebitis) and surrounding tissues.
directly to reduce the concentration of potassium in the plasma, by moving inwards cells used intravenous drip glucose - 40% solution of 200-300 ml and insulin at the rate of 3 g per 1 U of glucose, for 30 minutes.If there is an urgent need, it introduced an additional IV bolus insulin-- 15 units, a place with 40% glucose solution, 10 ml.
kaliyvyvodyaschih The use of diuretics, such as bumetanide, furosemide, is appropriate only in patients with preserved renal excretory function.At deficiency of aldosterone appropriate administration of its synthetic precursors - Ftorgidrokortizona or deoxycorticosterone acetate.
According to some level of potassium in the plasma can also be reduced by the introduction of beta-agonists, such as albuterol.It should inhale via inhaler for 10 minutes, the dose is 5 mg / ml.
Nepereotsenimymi, especially in the case of renal failure are extracorporeal treatment methods.Maximum efficiency with hyperkalemia demonstrates hemodialysis.With its help it is possible, for one four-hour session, to reduce the level of potassium in the plasma at 40-50%.Also other extracorporeal methods, for example, peritoneal dialysis, but its efficiency is much lower.
Once the patient is stabilized, and urgent measures are completed, you can proceed to further maintain homeostasis and prevent the re-development of hyperkalemia.
For further maintenance therapy is appropriate to use any of the following remedial measures.It is recommended to take drugs that are synthetic analogs of aldosterone.Also prevent further development of hyperkalemia help kaliyvyvodyaschie diuretics - Bumetamid, Furosemide.Also for maintenance therapy is used cation exchange resin, which help to bind potassium in the gastrointestinal tract.