Hemodialysis exchangers

Acute neonatal hyperammonemia, irrespective of cause, is a medical emergency and requires immediate and rapid lowering of ammonia levels to prevent serious effects on the brain. Useful measures include hemodialysis, exchange transfusion, peritoneal dialysis, and administration of arginine hydrochloride. The general goals of management are to... 

FIGURE 20.9 Hemodialysis exchangers are disposable units similar to membrane oxygenators in construction, (a) Note the simple design of the device as shown in the upper portion of the figure (Artificial Organs Division, Travenol Laboratories, Inc., Deerfield, Illinois). (6) Close-up view of hollow fibers used to separate the patient s blood from the dialysate fluid. Toxins in the blood diffuse through the fiber walls to the dialysate fluid. 

Exchange transfusion that may be required in patients with P. falciparum malaria in whom parasitemia may be between 5% and 15% remains a questionable modality. Either peritoneal or hemodialysis may be indicated in renal failure. 

Dialysis, including hemodialysis and peritoneal dialysis, relieves acute toxicity during fulminant hyperammonemia. Exchange transfusions also have been performed, but this technique has not been equally useful in removing ammonia. 

In continuous ambulatory peritoneal dialysis (CAP )), approximately 21 of dialysate solution is infused into the patient s peritoneal cavity, and is exchanged with new dialysate about four times each day. The patient need not stay in bed, as with ordinary hemodialysis, but it is difficult to continue CAPD for many years due to the formation of peritoneal adhesions. 

Because digoxin has a large apparent volume of distribution, plasma exchange, hemodialysis, and hemoperfusion are not effective methods of removing digoxin from the body. 

The dosage of colchicine should be adjusted according to creatinine clearance during long-term use to avoid the risk of myoneuropathy (SEDA-16, 114). Colchicine should not be used in patients undergoing hemodialysis, since it cannot be removed by either dialysis or exchange transfusion (11). 

If patients have high plasma concentrations of poljmixins, neither hemodialysis nor peritoneal dialysis is effective in eliminating them (39). Exchange transfusion has been proposed (40,41). 

Polystyrene sulfonic acid has been used as sodium, potassium, and calcium salts. Sodium polystyrene sulfonate has been used to treat hyperkalemia in patients with renal insufficiency and as an adjuvant during hemodialysis. It can be given orally or rectally in all age groups (1). It has also been added to feeding formulae and nutritional supplements to reduce their potassium contents and so prevent hyperkalemia however, the reduction in potassium content was more than balanced by a concomitant increase in sodium content, presumably because of exchange of the sodium with calcium and magnesium (2,3). The uses and adverse effects of sodium polystyrene sulfonate have been reviewed (4,5). 

In this patient both plasma exchange and hemofiltration were effective in reducing the serum silver concentration, and their effects were additive, but hemodialysis was ineffective. However, none of these maneuvers affected brain silver concentrations. 

With double-lumen intravenous catheters for acute hemodialysis, hemperfusion, and plasma exchange, the most common complications are bleeding, hematomas, catheter failure, risk of infection, central vein thrombosis and stenoses, and rarely, air embohsm. Femoral placement is the site associated with the fewest non-in-fectious comphcations [16]. Comphcations of treatment will be discussed below. 

Just like for amatoxin intoxication, the treatment is mainly supportive care. Orellanine seems to be rapidly concentrated in renal tissue [97], making toxins extraction techniques such as hemoperfusion, hemodialysis or plasma exchange, probably ineffective [90,94]. Antioxydant therapy with N-acetylcysteine [98] and selenium [99] as well as corticosteroids treatment [90,98] were also proposed but the data are limited to case reports. 

Compared to patients treated by hemodialysis, data on trace element accumulation/ deficiency in CAPD are rather scanty and less documented. In CAPD the total volume of dialysis fluid patients get in contact with during treatment is much lower. Hence, the potential amount of trace metals that can be exchanged during treatment is much less than in hemodialysis. Therefore, CAPD patients must be considered at a lower risk for trace element accumulation/ toxicity as compared to hemodialysis a statement which is also reflected by the data presented of Padovese et al. [21] comparing the estimated exposure of forty-four trace elements in both patient groups. Distinct differences have been noted in the trace metal content between CAPD and hemodialysis fluids. Also the trace metal content of CAPD fluids may greatly differ between each other, which has been ascribed to the wide range of trace... 

In acute exposure prompt medical attention is critical. The victim should be immediately removed to fresh air and away from the source of exposure. Oxygen should be provided if there is a respiratory distress. Initial therapy should be directed at stopping the ongoing hemolysis by performing exchange transfusion. Currently there is no other treatment to decrease arsine hemolysis however, studies in vitro have shown that some dithiol chelators (meso-2,3-dimercaptosuccinic acid, DMSA 2,3-dimercapto-l-propanesulfonic acid, DMPS and 2,3-butanedithiol) are effective (see Further Reading). This should be followed by aims to restore renal function or compensate for lost renal function (hemodialysis). This process does not remove any formed arsenic from the exposed body. Administration of dimercaprol (British Anti-Lewisite, BAL) has no effect on arsine hemolysis, but it lowers blood arsenic levels resulting from arsine exposure. The use of chelators must be... 

No specific treatment is available for chloramphenicol exposure. Hemodialysis is ineffective. Charcoal hemoperfusion or whole blood exchange transfusion has been recommended in infants with serum concentrations of >50pgmH. Management is primarily supportive. 

Table 45-8 hsts the numerous medical comphcations of PD. An average PD patient absorbs up to 60% of the dextrose in each exchange. This continuous supply of calories leads to increased adipose tissue deposition, decreased appetite, malnutrition, and altered requirements for insulin in diabetic patients. Fibrin formation in dialysate is common and can lead to obstruction of catheter outflow. Infectious comphcations of PD are a major cause of morbidity and mortality and are the leading cause of technique failure and transfer from PD to hemodialysis. The two predominant infectious complications are peritonitis and catheter-related infections, which include both exit-site and tunnel infections. 

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