Citrate anticoagulation during in vivo simulation of slow hemofiltration.

Citrate anticoagulation has been used as an alternative to heparin for hemodialysis in high-risk patients; however, its use in hemofiltration has not been well studied. We examined citrate in 6 patients placed on slow hemofiltration for up to 6 h duration. During the experiments, the systemic citrate level increased from a baseline average of 0.15 to 0.55 mmol/l, and then decreased to 0.27 mmol/l. The citrate was freely filtered. The systemic total and ionized calcium decreased very slightly and no untoward effects were noted. Anticoagulation was successful. This preliminary study suggests that citrate anticoagulation can be used in slow hemofiltration.

Natriuretic effect of digoxin-like immunoreactive substance on dog kidney.

We previously reported that digoxin-like immunoreactive substance (DLIS) was found only in the blood of those dialysis patients who were hypertensive and had high systemic vascular resistance. In order to determine whether the DLIS was a marker for the natriuretic hormone, renal infusion studies were carried out in anesthetized dogs. When ultrafiltrates from patients with high blood DLIS levels were infused into the renal artery of one kidney there was a significant increase in the fractional excretion of sodium (FE Na) from its baseline value. Further, the FE Na of these kidneys were significantly higher than the FE Na noted for the contralateral kidneys which were simultaneously infused with ultrafiltrates obtained from dialysis patients lacking DLIS activity in their blood. We conclude that the DLIS is or represents a marker for natriuretic hormone. Since the natriuresis noted was independent of renal plasma flow and glomerular filtration rate and since the fractional excretion of potassium was not influenced by the infusion, we believe that DLIS is different from atrial natriuretic factor.

Long-term blood access by catheters implanted into arteriovenous fistulas of sheep.

Reliable long-term blood access in sheep was provided by implanting one or two catheters into the high velocity blood flow in the vein draining an arteriovenous fistula created in the neck. Thrombosis of the catheterized vein occurred in only one of 31 cases in which a catheter with rounded intravascular tip was used, as compared with seven in 10 cases using a sharp-tipped catheter. The mean duration of placement for all rounded-tip catheters was 228.6 days. Extrusion from the vessel occurred with 3 of 8 short catheters (2 cm intravascular length), but only after a period of more than seven months of implantation. Using a program of trice-weekly disinfection of the skin exit site, exterior portion of the catheter, and catheter lumen resulted in failure of only two catheters due to infection. Rounded-tip catheters with 5 cm intravascular length had 75% life table functional rate at 15 months. Implantation of two catheters permitted extracorporeal circulation at flows of up to 300 ml/min using a blood pump to withdraw blood from one catheter while simultaneously returning it through the second.