Forced diuresis
Last reviewed: 23.04.2024
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Forced diuresis as a method of detoxification is based on the use of drugs that contribute to a sharp increase in diuresis, this is the most common method of conservative treatment of poisoning, in which excretion of hydrophilic toxicants is performed primarily by the kidneys.
These goals are best met by osmotic diuretics (mannitol), the clinical use of which was initiated by the Danish doctor Lassen in 1960. The osmotic diuretic is distributed only in the extracellular sector, is not subjected to metabolic transformations, is completely filtered through the basal membrane of the glomerulus, not reabsorbed in the tubule apparatus of the kidney. Mannitol is a widely used osmotic diuretic. It spreads only in the extracellular environment, is not metabolized, not reabsorbed by the tubules of the kidneys. The volume of mannitol distribution in the body is about 14-16 liters. Mannitol solutions do not irritate the intima of the veins, if ingested under the skin do not cause necrosis, injected intravenously as a 15-20% solution of 1.0-1.5 g / kg. The daily dose is not more than 180 g.
Furosemide is a strong diuretic (saluretic) remedy, whose action is related to inhibition of the reabsorption of Na + and Cl ions, to a lesser extent - K +. The efficacy of the diuretic effect of the drug used in a single dose of 100-150 mg is comparable to that of osmotic diuretics, however, when it is repeated, more significant losses of electrolytes, especially potassium, are possible.
The method of forced diuresis is considered quite a universal way of accelerated removal from the body of various toxic substances, including barbiturates, morphine, organophosphorous insecticides (FOI), quinine and pachycarpine hydroiodide, dichloroethane, heavy metals and other drugs excreted from the kidneys. The effectiveness of the diuretic therapy is significantly reduced as a result of the formation of a strong bond of many chemicals that enter the body, with proteins and lipids of the blood, as noted, for example, by poisonings with phenothiazines, clozapine, etc. When poisoning with toxicants giving an aqueous reaction in an aqueous solution barbiturates, salicylates, etc.), previously alkalinized blood by intravenous sodium bicarbonate (4% solution of 500 ml).
Forced diuresis always conducts in three stages a preliminary water load, a rapid introduction of a diuretic and a substitution infusion of solutions of electrolytes.
[The following procedure of forced diuresis is recommended
Precompensation is made for the development of hypovolemia developing during severe poisoning by intravenous injection of plasma-substituting solutions. Simultaneously, the concentration of toxic substance in the blood and urine, hematocrit is determined and a permanent urinary catheter is used to measure the hourly urine output. Mannitol (15-20% solution) is injected intravenously in an amount of 1.0-1.5 g per kg of body weight of the patient for 10-15 minutes, then - electrolyte solution at a rate equal to the rate of diuresis. A high diuretic effect (500-800 ml / h) is maintained for 3-4 hours, after which the osmotic equilibrium is restored. If necessary, the whole cycle is repeated, but no more than twice to avoid the development of osmotic nephropathy. The combined use of osmotic diuretics with saluretics (furosemide) provides an additional opportunity to increase the diuretic effect by a factor of 1.5, but the high rate and large volume of forced diuresis, reaching 10-20 l / day, conceal the potential danger of rapid elution of plasma electrolytes from the body.
To correct possible violations of the salt balance, a solution of electrolytes is introduced.
The method of forced diuresis is sometimes called the washing of blood, since the associated water-electrolyte load puts higher demands on the cardiovascular system and the kidneys. Strict account of the injected and isolated fluid, the definition of hematocrit and CVP allow easy control of the body's water balance during the treatment, despite the high rate of diuresis.
Complications of the method of forced diuresis (hyperhydration, hypokalemia, hypochloraemia) are associated only with a violation of the technique of its use. To avoid thrombophlebitis at the site of administration of solutions recommend central vein catheterization. With long-term use of osmotic diuretics (more than 3 days), osmotic nephrosis and arthritis can be developed. Therefore, the duration of forced diuresis is usually limited by these terms, and osmotic diuretics are combined with saluretics.
The method of forced diuresis is contraindicated in intoxications complicated by acute cardiovascular insufficiency, as well as in disorders of kidney function (oliguria, azotemia, an increase in creatinine levels of more than 221 mmol / l, due to low filtration volume). In patients older than 50 years, the effectiveness of the method of forced diuresis for the same reason is markedly reduced.