Dialysis metabolic acidosis

Patients with acute hyperkalemia usually require other therapies to manage hyperkalemia until dialysis can be initiated. Patients who present with cardiac abnormalities caused by hyperkalemia should receive calcium gluconate or chloride (1 g intravenously) to reverse the cardiac effects. Temporary measures can be employed to shift extracellular potassium into the intracellular compartment to stabilize cellular membrane effects of excessive serum potassium levels. Such measures include the use of regular insulin (5 to 10 units intravenously) and dextrose (5% to 50% intravenously), or nebulized albuterol (10 to 20 mg). Sodium bicarbonate should not be used to shift extracellular potassium intracellularly in patients with CKD unless severe metabolic acidosis (pH less than 7.2) is present. These measures will decrease serum potassium levels within 30 to 60 minutes after treatment, but potassium must still be removed from the body. Shifting potassium to the intracellular compartment, however, decreases potassium removal by dialysis. Often, multiple dialysis sessions are required to remove potassium that is redistributed from the intracellular space back into the serum. 

Treatment of metabolic acidosis in CKD requires pharmacologic therapy. Other disorders that may contribute to metabolic acidosis should also be addressed. Altering bicarbonate levels in the dialysate fluid in patients receiving dialysis may assist with the treatment of metabolic acidosis, although pharmacologic therapy may still be required. 

Metabolic acidosis in patients undergoing dialysis can often be managed by using higher concentrations of bicarbonate or acetate in the dialysate. 

In a 23-year-old woman, a kidney allograft recipient with recurrent lymphoceles treated with povidone-iodine irrigations (50 ml of a 1% solution bd for 6 days), a metabolic acidosis occurred and renal function deteriorated. After a few days, despite suspension of irrigation, the patient developed oliguria, and dialysis was needed. A renal biopsy showed acute tubular necrosis. 

There are three specific modalities of treatment for severe methanol poisoning suppression of metabolism by alcohol dehydrogenase to toxic products, dialysis to enhance removal of methanol and its toxic products, and alkalinization to counteract metabolic acidosis. 

Therapeutically, sodium bicarbonate may be used as an antacid, and as a source of the bicarbonate anion in the treatment of metabolic acidosis. Sodium bicarbonate may also be used as a component of oral rehydration salts and as a source of bicarbonate in dialysis fluids. 

The prevention and treatment of severe metabolic acidosis in patients with kidney disease is also important to prevent the development of renal bone disease, fatigue, decreased exercise tolerance, reduced cardiac contractility, and increased ventricular irritability. Metabolic acidosis also appears to stimulate protein catabolism, which can contribute to a negative nitrogen balance and lower albumin concentrations, as well as cause growth retardation in children. Lower serum bicarbonate levels in peritoneal dialysis patients have also been associated with a higher hospitalization rate and longer hospital stays. Severe acidemia (blood pH <7.1 to 7.2) suppresses myocardial contractility, predisposes patients to cardiac arrhythmias, and may lead to a decrease in total peripheral vascular resistance and blood pressure, reduced hepatic blood flow, and impaired oxygen delivery. ... 

Metabolic acidosis in both adult and pediatric patients undergoing dialysis can often be managed by using higher concentrations of bicarbonate or acetate in the dialysate (>38 mEq/L bicarbonate is safe and effective). Administration of oral bicarbonate salts as described above may also be necessary for some patients. 

D. Enhanced elimination. Hemodialysis rapidly removes both methanol (half-life reduced to 3-6 hours) and formate. The indications for dialysis are suspected methanol poisoning with significant metabolic acidosis, visual abnormalities, an osmolar gap greater than 10 mOsm/L, or a measured serum methanol concentration greater than 50 mg/dL. Dialysis should be continued until the methanol concentration is less than 20 mg/dL. 

Dialysis patients with ESRD tend to have a poor appetite. Protein metabolism is also altered in the setting of chronic acidosis and low-grade inflammation. These factors in combination place patients at risk of protein and energy mainourishment. Plasma albumin is often used as a marker of malnutrition even though it is a relatively poor nutritional marker. However, there is good evidence that the lower the plasma concentration of albumin, the worse the long-... 

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