Improving the delivery of continuous renal replacement therapy using regional citrate anticoagulation.

AIMS: Regional citrate anticoagulation during acute renal replacement therapy (RRT) effectively prevents extracorporeal thrombosis and avoids bleeding risk. There have been a number of citrate anticoagulation protocols published; but a simple and predictable scheme with standardized components and procedures, as well as clearly defined citrate pharmacokinetics, is needed for continuous RRT (CRRT) that is now used frequently in the critical care setting. The present study sets forth methodology with standardized blood flow and dialysate composition, and with citrate and calcium infusions that are quantitatively linked to extracorporeal blood flow rate--a predictable and easily replicated CRRT paradigm. MATERIALS AND METHODS: CRRT using continuous venovenous hemofiltration with dialysis (CVVHD) was standardized using 150-200 ml/min blood flow, calcium-free dialysate with only moderate sodium (135 mEq/l) and bicarbonate (28 mEq/l) concentrations, and ultrafiltration limited to that needed for overall fluid balance in the intensive care unit. Citrate infusion (ACD-A solution) into the extracorporeal blood and calcium repletion in blood returned to the patient were proportional to blood flow. Anticoagulation was accomplished by keeping extracorporeal ionized calcium below 0.4 mM/l. Filter performance, citrate removal and changes in calcium, sodium and alkali were evaluated longitudinally. RESULTS: CVVHD using this protocol delivered urea clearance exceeding 2 l/h (48 l/d) when filter function was sustained. Filter longevity was markedly improved using citrate when compared with standard heparin anticoagulation, and nursing time spent on initiating and troubleshooting CRRT was approximately halved using this protocol. Sieving coefficients for urea, creatinine and citrate were approximately 0.9 and were sustained through nearly 3 days of filter use. Citrate clearance and removal were quantitatively linked to dialysate and ultrafiltration flow, resulting in 35-50% direct removal of the citrate-calcium chelate and reduced systemic citrate load. Serum tonicity and acid-base status were not problematic. The only notable side effect was modest calcium accumulation that necessitated reduction in calcium repletion rate. CONCLUSIONS: CVVHD is well suited to regional citrate anticoagulation. The present protocol is straightforward and predictable, with minor metabolic consequences that can be anticipated and adjusted. These results commend regional citrate anticoagulation to wider application.

Case management of the anemic patient. Epoetin alfa: focus on inflammation and infection.

Response to Epoetin alfa can be influenced by several factors, including the presence of inflammation or infection. It is important that nurses monitor patients so that possible undesirable effects of inflammation or infection can be avoided or minimized.

Preventing Staphylococcus aureus infection during chronic peritoneal dialysis.

In the interest of studying the prevention of chronic peritoneal dialysis infections, serial studies of the bacterial epidemiology in peritonitis and of antibiotic prophylaxis, respectively, were carried out. For 18 months, prospective evaluation of catheter exist site cultures, performed at the time patients developed acute peritonitis, showed that Staphylococcus aureus peritonitis was associated with concordant S. aureus at the exist site in 85% of cases, significantly more frequent than that for other organisms (P less than 0.02). Furthermore, active inflammation along with concordant culture results at the exit site characterized more than 60% of S. aureus peritonitis cases, also significantly more than that for other organisms (P less than 0.01). Over the ensuing 2 yr, patients beginning chronic peritoneal dialysis with a new percutaneously placed catheter were prospectively entered into a randomized, controlled trial of long-term antibiotic prophylaxis with trimethoprim-sulfamethoxasole. Patients receiving prophylaxis tended to have fewer episodes of peritonitis; however, the lower rate of peritonitis reached statistical significance only comparing patients who were S. aureus carriers at entry into the study to patients who were not S. aureus carriers. In particular, the prophylaxis trial seemed to reduce the specific incidence of S. aureus peritonitis overall, with S. aureus appearing in only 2 of 28 total peritonitis episodes among treated patients as compared with 11 of 37 total episodes among non-treated patients (P less than 0.01). Further analysis of the time to first peritonitis suggests that the effect of prophylaxis was most prominent during the first 3 months of therapy (P less than 0.02) rather than later in the course of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of quinapril and its active metabolite quinaprilat during continuous ambulatory peritoneal dialysis.

The pharmacokinetics of quinapril, a novel angiotensin converting enzyme (ACE) inhibitor, and its active metabolite, quinaprilat, were determined following a single 20-mg oral dose of quinapril in six patients with chronic renal failure maintained on continuous ambulatory peritoneal dialysis (CAPD). Overall, quinapril was well tolerated by these CAPD patients, with mild and transient side effects, not unexpected in this clinical setting, which included pruritus, headache, nausea, and cough. Blood pressure reduction was observed in four of six patients, with onset reliably two to four hours after dosing and duration up to 48 hours, associated with quinaprilat concentrations in plasma above 90 ng/mL for at least 33 hours postdose. Two patients experienced significant hypotension, systolic blood pressure below 90 mm Hg, which responded promptly to oral fluid administration and/or reduction in dialysate tonicity. The pharmacokinetic profile of quinapril in these CAPD patients was not significantly different from that previously observed in healthy subjects with normal renal function and in patients with moderate to severe renal dysfunction not yet requiring dialysis (RDND). The apparent elimination half-life of quinapril was approximately one hour, with negligible dialysate excretion. The pharmacokinetic profile of quinaprilat in these CAPD patients was similar to that previously observed in patients with RDND. The elimination half-life of quinaprilat was markedly prolonged when compared to that in healthy subjects and averaged 20 hours, with only a small amount of quinaprilat excreted in dialysate (mean = 2.6% of total dose).(ABSTRACT TRUNCATED AT 250 WORDS)

The curled catheter: dependable device for percutaneous peritoneal access.

The curled peritoneal dialysis catheter is theoretically less prone to catheter migration and drainage failure. It also allows percutaneous placement, rather than surgical placement exclusively, whenever desired or necessary. Review of 213 curled-catheter placements, 134 (63%) percutaneous and 79 (37%) surgical, over the last 4 years, shows that the probability of continuing catheter function by life-table analysis was 88% at one year, 71% at 2 years, and 61% at three years, with no difference comparing percutaneous to surgical placement. Among the 213 total cases, nearly 50% of all catheters were still functioning at last follow up, and 38 catheters (17.8%) have been lost in total, attributed to infectious complications in 24 cases (tunnel-exit infection alone in 5, peritonitis alone in 11, combined infection in 8), refractory drain failure in 9 cases (early drain failure in 4, late drain failure in 5), recurrent late subcutaneous dialysate leaking in 3 cases, and peri-catheter hernia in 2 cases. Among other complications, the incidence of early drain failure (7.0%), and late drain failure (4.2%), compare favorably to reports describing other devices or other placement methods having comparable size of reported experience. Analyzing our own percutaneous and surgical placements separately, there were no differences in the respective frequencies of early drain failure, late drain failure, late subcutaneous dialysate leaking, outer cuff extrusion, required hernia repair, peritonitis or tunnel-exit infection. Only early external dialysate leaking was more frequent using percutaneous placement methods (21.6% vs. 10.1%; p less than 0.05), although no catheters were lost due to early external leaking.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter peritonitis during chronic peritoneal dialysis.

Among gram-negative bacilli isolated during peritonitis in chronic peritoneal dialysis (CPD), Pseudomonas species are most common but Acinetobacter species are nearly as frequent. A survey of more than 450 patient-years' experience with CPD revealed 23 episodes of Acinetobacter peritonitis (AP), making this the second most common form of gram-negative peritonitis. Concomitant break in sterile technique and exit-site/tunnel infection were infrequent. AP appeared as the first peritonitis episode in five cases and as the second in six cases, and the duration of CPD at the time of AP ranged from less than 1 to greater than 56 months. However, AP was noted to appear shortly after treatment of another peritonitis episode or shortly after CPD access placement, within 2 months in 11 cases (47%) and within 3 months in 14 cases (61%). Treatment with intraperitoneal antibiotics succeeded in 21 cases (91%) without CPD interruption or catheter removal, with tobramycin or gentamicin alone in 16 cases, and with combined aminoglycoside and penicillin or cephalosporin in six cases. In two cases intraperitoneal antibiotics alone were insufficient therapy: one case with concomitant tunnel infection and dialysate leak and one case with bacteremia while receiving corticosteroids. The time-dependent incidence of AP suggests opportunistic infection during a vulnerable period in the first 2 to 3 months following another peritonitis episode, but AP also appears amenable to intraperitoneal antibiotic therapy alone without interruption of the CPD routine in the majority of cases.