Continuous Arteriovenous Hemodialysis Research Articles

Evolution of Technology for Continuous Renal Replacement Therapy: Forty Years of Improvement.

Continuous arteriovenous hemofiltration (CAVH) was proposed in 1977 as an alternative treatment for acute renal failure in patients in whom peritoneal dialysis or hemodialysis was clinically or technically precluded. In the mid-1980s, this technique was extended to infants and children. CAVH presented important advantages in the areas of hemodynamic stability, control of circulating volume, and nutritional support. However, there were serious shortcomings such as the need for arterial cannulation and limited solute clearance. These problems were solved by the introduction of continuous arteriovenous hemodiafiltration and continuous arteriovenous hemodialysis, where uremic control could be achieved by increasing countercurrent dialysate flow rates to 1.5 or 2 L/h as necessary, or by venovenous techniques utilizing a double-lumen central venous catheter for vascular access. Thus, continuous venovenous hemofiltration replaced CAVH because of its improved performance and safety. From the initial adoptive technology, specific machines have been designed to permit safe and reliable performance of the therapy. These new machines have progressively undergone a series of technological steps that have resulted in the evolution of highly sophisticated equipment utilized today. A significant number of advances have taken place since the time continuous renal replacement therapy was initiated. In particular, there have been successful experiments with high-volume hemofiltration and high-permeability hemofiltration. The additional and combined use of sorbent has also been tested successfully. Progress has been made in the technology as well as the understanding of the pathophysiology of acute kidney injury. Today, new biomaterials and new devices are available and new frontiers are on the horizon. Although improvements have been made, a lot remains to be done. Critical care nephrology is expected to further evolve in the near future, especially in the area of information and communication technology, utilization of big data and large database registries, biofeedback, and assisted prescription and treatment delivery, with high potential for improvement in morbidity and mortality of the most severely ill patients.

Evolution of Technology for Continuous Renal Replacement Therapy: Forty Years of Improvements.

Continuous arteriovenous hemofiltration (CAVH) was proposed in 1977 as an alternative treatment for acute renal failure in patients in whom peritoneal dialysis or hemodialysis was clinically or technically precluded. In the mid-1980s, this technique was extended to infants and children. CAVH presented important advantages in the areas of hemodynamic stability, control of circulating volume, and nutritional support. However, there were serious shortcomings such as the need for arterial cannulation and limited solute clearance. These problems were solved by the introduction of continuous arteriovenous hemodiafiltration (CAVHDF) and continuous arteriovenous hemodialysis (CAVHD) where uremic control could be by increasing countercurrent dialysate flow rates to 1.5 or 2 liters/h as necessary, or by venovenous techniques utilizing a double-lumen central venous catheter for vascular access. Thus, continuous venovenous hemofiltration replaced CAVH because of its improved performance and safety. From the initial adoptive technology, specific machines have been designed to permit safe and reliable performance of the therapy. These new machines have progressively undergone a series of technological steps that have resulted in the highly sophisticated equipment utilized today. A significant number of advances have taken place since the beginning of continuous renal replacement therapy. In particular, there have been successful experiments with high-volume hemofiltration and high-permeability hemofiltration. The additional and combined use of sorbent has also been tested successfully. Progress has been made in the technology as well as the understanding of the pathophysiology of acute kidney injury. Today, new biomaterials and new devices are available and new frontiers are on the horizon. Although improvements have been made, a lot remains to be done. Critical care nephrology is expected to further evolve in the near future, especially in the area of information and communication technology, utilization of big data and large database registries, biofeedback, and assisted prescription and treatment delivery, with high potential for improvement in morbidity and mortality of the most severely ill patients.

Short-term survival of hyperammonemic neonates treated with dialysis.

In severe neonatal hyperammonemia, extracorporeal dialysis (ECD) provides higher ammonium clearance than peritoneal dialysis (PD). However, there are limited outcome data in relation to dialysis modality. Data from infants with hyperammonemia secondary to inborn errors of metabolism (IEM) treated with dialysis were collected in six Italian centers and retrospectively analyzed. Forty-five neonates born between 1990 and 2011 were enrolled in the study. Of these, 23 were treated with PD and 22 with ECD (14 with continuous venovenous hemodialysis [CVVHD], 5 with continuous arteriovenous hemodialysis [CAVHD], 3 with hemodialysis [HD]). Patients treated with PD experienced a shorter duration of predialysis coma, while those treated with HD had a shorter ammonium decay time compared with all the other patients (p < 0.05). No difference in ammonium reduction rate was observed between patients treated with PD, CAVHD or CVVHD. Carbamoyl phosphate synthetase deficiency (CPS) was significantly associated with increased risk of death (OR: 9.37 [1.52-57.6], p = 0.016). Predialysis ammonium levels were significantly associated with a composite end-point of death or neurological sequelae (adjusted OR: 1.13 [1.02-1.27] per 100μmol/l, p = 0.026). No association was found between outcome and dialysis modality. In this study, a delayed ECD treatment was not superior to PD in improving the short-term outcome of neonates with hyperammonemia secondary to IEM.

Continuous renal replacement therapy (CRRT) for rhabdomyolysis

Rhabdomyolysis is a condition that is characterised by the breakdown of skeletal muscle tissue and leakage of intracellular myocyte contents into circulating blood. Rhabdomyolysis can lead to acute kidney injury (AKI) and is a potentially life-threatening condition. Studies have indicated that continuous renal replacement therapy (CRRT) may provide benefits for people with rhabdomyolysis by removing potentially damaging myoglobin and stabilising haemodynamic and metabolic status. We aimed to: i) assess the efficacy of CRRT in removing myoglobin; ii) investigate the influence of CRRT on mortality and kidney-related outcomes; and iii) evaluate the safety of CRRT for the treatment of people with rhabdomyolysis. We searched the Cochrane Renal Group's Specialised Register to 6 January 2014 through contact with the Trials' Search Co-ordinator using search terms relevant to this review. We also searched China National Knowledge Infrastructure (from 1 January 1979 to 16 April 2013) and the Chinese Clinical Trials Register (to 16 April 2013). All randomised controlled trials (RCTs) and quasi-RCTs that investigated clinical outcomes of CRRT for people with rhabdomyolysis were included. Two authors independently assessed studies for inclusion and extracted data. We derived risk ratios (RR) for dichotomous data and mean differences (MD) for continuous data with 95% confidence intervals (CI). Methodological risk of bias was assessed using the Cochrane risk of bias tool. Of the three included studies (101 participants), one evaluated continuous arteriovenous haemodialysis and two investigated continuous venovenous haemofiltration; all included conventional therapy as control.We found significant decreases in myoglobin in patients among whom CRRT therapy was initiated on days four, eight, and 10 (day 4: MD -11.00 (μg/L), 95% CI -20.65 to -1.35; Day 8: MD -23.00 (μg/L), 95% CI -30.92 to -15.08; day 10: MD -341.87 (μg/L), 95% CI -626.15 to -57.59) compared with those who underwent conventional therapy.Although CRRT was associated with improved serum creatinine, blood urea nitrogen, and potassium levels; reduced duration of the oliguria phase; and was associated with reduced time in hospital, no significant differences were found in mortality rates compared with conventional therapy (RR 0.17, 95% CI 0.02 to 1.37). The included studies did not report on long-term outcomes or prevention of AKI.Overall, we found that study quality was suboptimal: blinding and randomisation allocation were not reported by any of the included studies, leading to the possibility of selection, performance and detection bias. Although CRRT may provide some benefits for people with rhabdomyolysis, the poor methodological quality of the included studies and lack of data relating to clinically important outcomes limited our findings about the effectiveness of CRRT for people with rhabdomyolysis.There was insufficient evidence to discern any likely benefits of CRRT over conventional therapy for people with rhabdomyolysis and prevention of rhabdomyolysis-induced AKI.

Renal replacement therapy in support of combat operations

Renal replacement therapy has been used by the U.S. Army at the combat support hospital echelon of care since the Korean conflict. Although there has been a general decline in the incidence of wartime acute kidney injury, the mortality associated with acute kidney injury and the use of renal replacement therapy remain unchanged, in the range of 60% to 80%. The U.S. Army official doctrine is that field dialysis is provided through a specialized Hospital Augmentation Team; however, this team has not been deployed to either Iraq or Afghanistan as a result of the ability to rapidly evacuate most cases requiring renal replacement therapy. The history of wartime renal replacement therapy is reviewed along with the general epidemiology of battlefield acute kidney injury and renal replacement therapy. Recent literature documents cases of renal replacement therapy performed in and out of theater in support of the current operations. In-theater renal replacement therapy has been provided through a variety of modalities, including conventional hemodialysis, peritoneal dialysis, and both continuous venovenous and continuous arteriovenous hemodialysis. Out of theater, casualties have received both intermittent and continuous hemodialysis at Landstuhl Regional Medical Center and Walter Reed Army Medical Center, whereas patients sustaining burns have undergone aggressive continuous venovenous hemofiltration or hemodiafiltration at Brooke Army Medical Center. Acute kidney injury requiring renal replacement therapy in wartime casualties is an uncommon occurrence but one with extremely high mortality. Future doctrine should be prepared for contingencies in which the incidence may be increased as a result of mass crush injury casualties or prolonged evacuation times.

Continuous Arteriovenous Hemodialysis and Continuous Venovenous Hemofiltration in Burn Patients with Acute Renal Failure

Acute renal failure (ARF) is a very common condition that may occur in patients with major burn injuries. The majority of burn patients with ARF have a high mortality rate, ranging from 73% to 100%. There are several ways to treat ARF in burn patients, including peritoneal dialysis (PD), intermittent hemodialysis, and continuous renal replacement therapy (CRRT). CRRT is generally used in patients in whom intermittent hemodialysis has failed to control hypovolemia, as well as in patients who cannot tolerate intermittent hemodialysis. Additionally, PD is not suitable for patients with burns within the abdominal area. For these reasons, most patients with unstable hemodynamic conditions receive CRRT. In this study (conducted in our burn unit between 1997 and 2004), six burn patients received CRRT: three received continuous arteriovenous hemodialysis (CAVHD) and the other three received continuous venovenous hemofiltration (CVVH). The patients were all males, with a mean age of 49.8 years (range, 27-80 years), and a mean burnt surface area of 65.1% (range, 30-95%). Four patients died due to multiple organ failure, and two patients recovered from severe ARF. CRRT has been proven safe and useful for burn patients with ARF. According to this study, we conclude that CVVH is an appropriate tool for treating ARF, with a lower incidence of vascular complications than CAVHD.

Subcutaneous pulsating neck mass after left internal jugular venipuncture

78-YEAR-OLD FEMALE patient was transferred to this hospital. She had a past history of coronary artery bypass grafting, sick sinus syndrome with pacemaker implantation, and chronic heart failure. Her symptoms were productive cough and orthopnea. Central venous cannulation via the left internal jugular vein was attempted. After local anesthesia with 1% lidocaine into the skin and subcutaneous tissue, the left internal jugular vein was approached anteriorly. At first, nonpulsatile and dark venous-like blood was obtained. However, the guide wire could not be advanced because of unusual high resistance. On the second try, nonpulsatile and dark red blood was obtained again. The catheter was inserted by the Seldinger method, but, surprisingly, pulsatile bleeding with bright red arterial blood was found to be coming from the catheter. The catheter was then withdrawn. A central venous pressure catheter was then placed in the femoral vein. Continuous arteriovenous hemodialysis with a heparin infusion was begun to treat her renal dysfunction because of a low cardiac output syndrome. Three days later, a subcutaneous mass was noticed in the left side of her neck at the site of the previous venipuncture attempt. The mass was growing gradually to the size of an egg with pulsation. Figure 1 shows a surface echo-examination of this mass. What is the diagnosis?

Physiological changes induced by continuous arteriovenous hemodialysis during liver transplantation

Physiological changes induced by continuous arteriovenous hemodialysis during liver transplantation

Extracorporeal dialysis in neonatal hyperammonemia: modalities and prognostic indicators.

We investigated the prognostic indicators in ten hyperammonemic neonates: four treated by continuous arteriovenous hemodialysis (CAVHD), four with continuous venovenous hemodialysis (CVVHD), and two with hemodialysis (HD). Plasma ammonium levels decreased significantly within the first 24 h irrespective of dialysis modality (from 1419 to 114 micromol/l, median values; P<0.0001). CVVHD achieved the highest ammonium clearance. HD provided highest ammonium extraction but clearance was hampered by severe hemodynamic instability. Five patients had a good outcome (normal at follow-up of 9-59 months), five had poor outcome (four died and one has severe neurological damage). Total coma duration was shorter in patients who had a good outcome (47+/-11 vs 78+/-13 h; P=0.02). Remarkably, only coma duration before dialysis determined this difference (22.2+/-10.1 vs 48.8+/-11.2 h; P=0.02). In cases with good outcome, coma duration was <33 h, whereas the others exceeded this limit. The prognosis was not related to dialysis modality, rapidity in reducing ammonium levels or to the underlying metabolic defect. In conclusion, results showed CVVHD to be the optimal modality for extracorporeal ammonium detoxification. However, the most relevant indicator for prognosis was coma duration before the start of dialysis. Therefore, major efforts should be made to refer patients quickly to highly specialized centers.

CONTINUOUS ARTERIOVENOUS HEMODIAFILTRATION IN THE ACUTE TREATMENT OF HYPERAMMONAEMIA DUE TO ORNITHINE TRANSCARBAMYLASE DEFICIENCY

Background. Acute hyperammonemia caused by urea cycle disorder is a medical emergency for which immediate managements should be taken to minimize permanent brain damage. Among different enzyme defects, ornithine transcarbamylase deficiency (OTC) is one of the most common enzyme defect in urea cycle disorders. We utilized continuous renal replacement therapy techniques in the acute treatment of hyperammonemia due to ornithine transcarbamylase deficiency.Patients and methods. Three male neonates with elevated serum ammonia levels were shown, based on urine organic acid analysis and serum amino acid studies, to have OTC deficiency. Administration of sodium benzoate and sodium phenylacetate for activating alternative nitrogen waste pathway were used associated with protein restriction. Other modalities, including blood exchange transfusion, peritoneal dialysis, continuous renal replacement therapy were utilized in an attempt to lower serum ammonia concentration.Results. We report the successful use of continuous arteriovenous hemofiltration (CAVH), continuous arteriovenous hemodialysis (CAVHD), continuous arteriovenous hemodiafiltration (CAVHDF) in the acute management of hyperammonemia due to OTC deficiency. We also compared the ammonia clearance between peritoneal dialysis, exchange transfusion, CAVH, CAVHD and CAVHDF. It demonstrated the evidence that CAVHDF provides the best ammonia clearance.Conclusion. Continuous renal replacement therapy including CAVH, CAVHD, and CAVHDF may be the alternative techniques for acute management of hyperammonemia in inborn error of metabolism when dialysis machine is not available. Our data suggests CAVHDF provides the best ammonia clearance.

Influence of renal replacement therapy on outcome of patients with acute renal failure

Influence of renal replacement therapy on outcome of patients with acute renal failure

Cardiac transplantation for prosthetic valve endocarditis in a previously transplanted heart

Native valve endocarditis is a rare complication after heart transplantation.1,2,3 A 54-year-old male underwent cardiac transplantation for end-stage ischemic cardiomyopathy in March 1992. The immediate postoperative course was complicated by primary graft failure requiring high-dose inotropic support and the intra-aortic balloon pump. Acute renal failure developed and continuous arteriovenous hemodialysis was undertaken for 8 days. The patient received triple immunosuppression with cyclosporine, azathioprine, and prednisone, without induction therapy. The patient became febrile and severe mitral regurgitation and mitral valve vegetations were noted 36 days after the transplant by echocardiography. Blood cultures grew methicillin-resistant Staphylococcus aureus (MRSA). A CT scan of his head revealed 2 lesions consistent with septic emboli. He remained febrile despite treatment with vancomycin and fuscidic acid with adequate blood levels. An aminoglycoside was not used because MRSA in this institution is resistant. Because of uncontrolled sepsis with blood cultures persistently growing MRSA, the patient underwent mitral valve replacement with a St. Jude prosthesis 42 days after the transplant. At operation massive vegetations were found on the mitral valve leaflets and the infection was eroding the annulus. Postoperatively, he developed acute renal failure and required 3 further days of continuous arteriovenous hemodialysis. The same antibiotics were continued postoperatively. Seventeen days later, severe mitral regurgitation developed due to a paravalvar leak. The patient remained febrile and 1 blood culture was positive for MRSA. Transesophageal echocardiography demonstrated a paravalvar leak with adjacent vegetations. Because of ongoing sepsis and severe heart failure, retransplantation was undertaken 103 days after his original transplant. He received triple immunosuppression with 3 doses of OKT3. Cyclosporine levels were run at one-half the usual level, azathioprine at 50 mg per day, and prednisolone at 10 mg per day. The explanted heart showed dehiscence of 50% of the sewing ring of the mitral valve prosthesis and MRSA was cultured from the annulus. Eleven days after his retransplant procedure Candida albicans was grown from a pleural drain. Four months after his second transplant he developed signs and echocardiographic features of constrictive pericarditis. An attempt was made to perform a pericardiectomy but this proved technically impossible. Pericardial fluid contained white blood cells and C. albicans was grown. He underwent a course of amphotericin followed by fluconazole. Eight months following his retransplantation he developed lower back pain and nuclear magnetic resonance imaging revealed a discitis of the fourth lumbar disk, a 7-cm abdominal aortic aneurysm, and an abscess in continuity with these 2 lesions. He underwent resection of this mycotic abdominal aortic aneurysm and subsequently, removal of the infected disk material (MRSA was grown) which did not involve the epidural space. He received vancomycin postoperatively. He has evidence of moderately severe chronic constrictive pericarditis and has had intermittent low-grade fevers for which no cause has been found despite extensive evaluation. No organisms have been cultured from his blood, blood count and erythrocyte sedimentation rate are normal, and repeated transthoracic and transesophageal echocarFrom the Heart and Lung Transplant Unit, The Prince Charles Hospital, Brisbane, Australia,a and the University of Alabama at Birmingham, Department of Surgery, Birmingham, Alabama.b Submitted June 19, 1996; accepted February 12, 1999. Corresponding author: David C. McGiffin, MB, BS, FRACS, Professor of Surgery, University of Alabama at Birmingham, Division of Cardiothoracic Surgery, UAB Station, LHRB 780, Birmingham, Alabama 35294-0007. Office telephone: 205-9346580. Fax: 205-975-2526. Copyright © 1999 by the International Society for Heart and Lung Transplantation. 1053-2498/99/$–see front matter PII 1053-2498(99)00011-X

Dosage adjustment of fluconazole during continuous renal replacement therapy (CAVH, CVVH, CAVHD, CVVHD).

Continuous arterio-venous haemofiltration (CAVH), continuous veno-venous haemofiltration (CVVH), continuous arterio-venous haemodialysis (CAVHD) and continuous veno-venous haemodialysis (CVVHD) are increasingly used in patients with acute renal failure (ARF). The elimination rate of fluconazole varies considerably depending on the procedure used. (In Germany, fluconazole is approved for the treatment of life-threatening fungal infections caused by Candida spp. and Cryptococcus neoformans at a dosage of up to 800 mg day-1.) The elimination rate of fluconazole by CVVHD depends on the combined dialysate/ultrafiltrate flow rate, but is much higher than achieved with CVVH and intermittent dialysis, with a fluconazole clearance in patients with CVVHD 2 l h-1 exceeding the values of healthy persons. To achieve therapeutic plasma levels during continuous renal replacement therapy, the same loading dose as in patients without renal failure should be administered, followed by a maintenance dose that is adjusted for anuric patients by multiplying by a factor that takes into account the extracorporeal elimination of the absorbed dose (CAVH, CVVH x 2.2, ultrafiltrate flow 0.5 l h-1; CAVHD, CVVHD x 3.8, combined dialysate/ultrafiltrate flow 1.5 l h-1). Despite the broad therapeutic margin of fluconazole, drug monitoring is recommended to achieve therapeutic drug levels in life-threatening indications because there have been only a few investigations of this, all involving relatively low dosages (up to 200 mg day-1).

Cavhd: Transitioning from CAVH

The first major variation to CAVH was continuous arteriovenous hemodialysis (CAVHD). In the adaptation for CAVHD, dialysate is added to the circuit to achieve a countercurrent flow to the blood path. By the mechanism of diffusion, improvement in solute and uremic toxin clearance was achieved. With the addition of the dialysate to the circuit, accommodations must be made in the calculation of filter replacement fluids. Institutional standards of care for CAVHD must be developed to complement those for CAVH.

Acute renal failure and outcome of continuous arteriovenous hemodialysis (CAVHD) and continuous hemofiltration (CAVH) in elderly patients following cardiovascular surgery.

A total of 111 elderly patients from the cardiac surgery intensive care unit (ICU) with acute renal failure (ARF) were studied during a period of 7 years (1988-1994). Forty-two patients being operated for coronary bypass (CBP) (31 M, 11 F), 26 patients for valve replacement (VR) (18 M, 8 F), 20 patients for a combined operation of coronary bypass and valve replacement (CBP+VR) (14 M, 6 F) and 23 patients for resection of aneurysm of the abdominal aorta (ROAOAA) (11 M, 12 F). Average age of the patients was 70 +/- 4 yr (65-80). Their blood pressure on the first day of continuous renal replacement therapy (CRRT) was 75 +/- 19 mmHg (50-95) and was maintained at about 95 +/- 15 mmHg (70-120) by using vasopressor drugs. From the results of this study a survival of 38% was registered within the CBP group, 65% within the VR group, 45% within the CBP+VR group and 91% within the ROAOAA group. The overall survival in all of the patients was 58%. It was a high mortality (62%) within CBP group compared to that of 35%, 55% and 9% within the VR, CBP+VR and ROAOAA groups, respectively. This is because more patients with predisposing preoperative risk factors, e.g., hypertension (33%) and Diabetes (17%) etc were found in the CBP group, in addition to their post operative complications of which bleeding necessitating reoperations was encountered in 31%. Multiple organ failure (MOF) was a common major problem of which respiratory failure needing artificial ventilation was encountered in about 90% of the patients. The overall mortality was 42% in which the major cause of death was MOF/circulatory failure. Heart failure was the second cause of death. Other secondary complications, e.g., liver failure (n = 6) and atrial fibrillation (n = 11) etc. might have added to the high mortality in this study. The effect of CRRT on uremic control was measured by following-up of the daily levels of the serum urea and creatinine and a steady-state uremic control was achieved. We conclude that CRRT can be considered as a reliable artificial renal support for ARF in ICU elderly patients.

Circulating rather than adherent PMN are responsible for intra-dialyzer degranulation during haemodialysis: J.C. Bos, M.P.C. Grooteman, A.J. van Houte, M. Schoorl, M.J. Nubé. Departments of Haemodialysis and Immuno-haematology, Medical Centre, Alkmaar, Netherlands

A continuous dialysis technique such as continuous arteriovenous hemodialysis (CAVHD) could be an interesting alternative to frequent intermittent hemodialysis to treat acute renal failure (ARF) secondary to tumor lysis syndrome (TLS). However, because of massive release of intracellular solutes in TLS, CAVHD clearances need to be increased to treat this syndrome. Continuous arteriovenous hemodialysis using a high dialysate flow rate at 4 L/hr was assessed in TLS and ARF associated with severe hyperphosphatemia. A 0.6-m2 hollow-fiber polyacrylonitrile dialyzer (Multiflow 60; Hospal, St-Léonard, Québec, Canada) was used. Blood urea nitrogen and serum creatinine levels decreased, respectively, from 102.5 to 27.2 mg/dL and from 3.1 to 1.8 mg/dL during the 36 hours of treatment. Serum urate concentration was normal at the beginning of treatment (4.5 mg/dL) and decreased to 2.1 mg/dl by the end of CAVHD. Serum phosphorus decreased from 16.7 to 4.4 mg/dL after the 36 hours of treatment. The calcium × phosphorus product decreased from 111.1 to 42.1 by 28 hours and remained under 50 thereafter. Serum potassium was easily controlled with the addition of 2.5 mEq/L of KCI in dialysate and replacement solutions. No rebound increases in phosphorus or potassium were noted after cessation of therapy. Continuous arteriovenous hemodialysis clearances of urea, creatinine, phosphorus, and urate were measured at 2-hour intervals for the first 24 hours and at 4-hour intervals for the remaining 12 hours. They were 53.0 ± 2.3 mL/min, 43.7 ± 2.2 mL/min, 40.4 ± 1.9 mL/min, and 39.3 ± 1.9 mL/min (n =15), respectively. The 24-hour CAVHD clearance of urea was 76 L, which is equivalent to 8.5 hours of conventional hemodialysis. Extraction of phosphorus and potassium with CAVHD was, respectively, 8.28 g and 188.5 mEq for 36 hours. In conclusion, CAVHD optimized by high dialysate flow rate becomes a powerful purifying technique for the treatment of ARF and TLS. It provides excellent continuous clearances of small molecular weight solutes, resulting in a rapid and sustained control of serum urate, potassium, and calcium × phosphorus product, avoiding the potentially deleterious rebound effects seen after hemodialysis.

Experience with right ventricular assist devices for perioperative right-sided circulatory failure

Right-sided circulatory failure remains a significant source of morbidity and mortality for both cardiac transplant and left ventricular assist device recipients. We reviewed our experience with 11 patients who required a right ventricular assist device (RVAD) after either orthotopic heart transplantation or left ventricular assist device implantation. Variables analyzed included total time of RVAD support, hemodynamic and hematologic parameters, and parameters of end-organ perfusion. These were assessed at five time points: (1) at least 2 weeks before RVAD implantation, (2) intraoperatively just before RVAD insertion, (3) while on RVAD support, and, for those who survived, (4) just before RVAD explantation, and (5) off RVAD support. Survival was assessed as the ability to be weaned successfully from RVAD support. Urine output and serum transaminase levels were recorded throughout the period of RVAD support. Five patients received an ABIOMED 5000 BVS RVAD, and 6 received a Bio-Medicus centrifugal pump. Nine patients in the study underwent orthotopic heart transplantation and had development of right-sided circulatory failure from 0 to 96 hours after donor organ insertion, and 2 patients underwent left ventricular assist device implantation 12 to 48 hours before RVAD support. The mean time of RVAD support for survivors was 133.6 +/- 33.6 hours (range, 107 to 190 hours). Six patients were successfully separated from RVAD support, and 5 patients died while on RVAD support. Causes of death included sepsis (2), biventricular failure (2), and coagulopathy (1). Continuous arteriovenous hemodialysis was employed in 3 of 6 survivors and 1 of 5 nonsurvivors. Right ventricular assist devices work most effectively if implanted early enough to avoid significant, potentially irreversible end-organ injury. We liberally employ continuous arteriovenous hemodialysis, minimize the use of heparin immediately postoperatively, keep patients sedated, and continue RVAD support until the patient displays signs of hemodynamic and end-organ recovery as heralded by (1) a decrease in central venous pressure and, more importantly, a decrease in pulmonary artery diastolic pressure, (2) an increase in urine output, and (3) a decrease in serum transaminase levels.

Bicarbonate dialysate for continuous renal replacement therapy in intensive care unit patients with acute renal failure

Lactate-buffered peritoneal solution traditionally has been used as dialysate for continuous renal replacement therapy (CRRT) in the United States because no bicarbonate solution is commercially available. Since 1994, the Cleveland Clinic Foundation Dialysis Unit has prepared a bicarbonate solution (sodium 144 ± 3 mEq/L, HCO 3 37 ± 2 mEq/L, potassium 3 or 4 mEq/L, calcium 3.0 ± 0.3 mEq/L, and magnesium 1.4 ± 0.3 mg/dL) replicating the dialysate for chronic intermittent hemodialysis. No solute precipitation, as calcium or magnesium salts, were observed, and several cultures of the solution, performed at various time periods, remained negative. Fifty critically ill acute renal failure patients have been treated with bicarbonate-CRRT. All patients were in multiple organ failure and required mechanical ventilation; 37 were receiving vasopressors. Forty-four continuous venovenous hemodialysis sessions and eight continuous arteriovenous hemodialysis sessions were performed with a mean duration of 7.8 ± 6.1 days. The mean inflow dialysate rate was 1,249 ± 225 mL/hr and the mean outflow rate (dialysate plus ultrafiltration) was 1,399 ± 237 mL/hr; the inflow rate was constantly kept lower or equal to the outflow rate to avoid an enhanced potential for backfiltration. No related fever spikes or sepsis episodes were noted. The metabolic control achieved during bicarbonate-CRRT was good, with the following mean (±SD) daily values: blood urea nitrogen 70.3 ± 29.0 mg/dL, creatinine 3.6 ± 1.3 mg/dL, sodium 135.7 ± 3.7 mEq/L, potassium 4.6 ± 0.5 mEq/L, chloride 99.9 ± 4.6 mEq/L, carbon dioxide content 21.4 ± 3.4 mEq/L, calculated anion gap 14.4 ± 4.8 mEq/L, arterial pH 7.39 ± 0.05, arterial PCO 2 36.6 ± 5.4 mm Hg, total calcium 8.7 ± 0.9 mg/dL (corrected for albumin 9.6), phosphorus 4.2 ± 1.4 mg/dL, and magnesium 2.06 ± 0.26 mg/dL. A subgroup of 13 patients was treated with two dialysate types, lactate-based solution (Dianeal 1.5%; Baxter Healthcare Corporation, Deerfield, IL) for 3.2 ± 1.5 days and bicarbonate solution for 7.4 ± 1.6 days, and the obtained metabolic control under both types of dialysate was compared. Mean values ± SD (with probability values) obtained with lactate dialysate versus bicarbonate dialysate were as follows: blood urea nitrogen 77.6 ± 34.4 mg/dL versus 71.0 ± 20.8 mg/dL ( P = NS), creatinine 4.1 ± 0.9 mg/dL versus 3.3 ± 1.6 mg/dL ( P = NS), sodium 132.8 ± 4.8 mEq/L versus 135.6 ± 2.9 mEq/L ( P = 0.04), chloride 95.8 ± 5.4 mEq/L versus 98.5 ± 4.2 mEq/L ( P = NS), carbon dioxide content 17.8 ± 3.1 mEq/L versus 21.8 ± 3.4 mEq/L ( P = 0.002), calculated anion gap 19.3 ± 4.4 mEq/L versus 15.2 ± 3.8 mEq/L ( P = 0.008), arterial pH 7.36 ± 0.07 versus 7.40 ± 0.06 ( P = NS), arterial PCO 2 32.1 ± 5.3 mm Hg versus 37.8 ± 3.8 mm Hg ( P = 0.01), total calcium 8.3 ± 1.1 mg/dL versus 8.8 ± 1.0 mg/dL ( P = NS), phosphorus 4.7 ± 1.3 mg/dL versus 3.8 ± 1.4 mg/dL ( P = NS), magnesium 1.95 ± 0.14 mg/dL versus 2.04 ± 0.34 mg/dL ( P = NS), and glucose 200.5 ± 80.4 mg/dL versus 146.7 ± 40.4 mg/dL ( P = 0.04). The bicarbonate solution is simple to prepare and is cost-effective. In our experience, its use as dialysate for CRRT is safe, free of complications, and provides an excellent metabolic control.

Continuous treatment modalities in acute renal failure

Continuous treatment modalities have become well established in the treatment of severely ill patients with acute renal failure since the introduction of continuous arteriovenous haemofiltration. However, this simple blood-pressure-driven treatment often fails to control azotaemia, especially in haemodynamically unstable patients with hypercatabolism. The common feature of further developments in continuous treatment modalities, such as continuous arteriovenous haemodialysis, venovenous haemofiltration, or venovenous haemodialysis is their higher efficacy in controlling azotaemia. Venovenous forms of treatment involve considerably higher technical requirements. The main advantages of continuous forms of treatment as opposed to intermittent haemodialysis are greater haemodynamic stability and the possibility of adapting nutrition without restriction to the needs of the critically ill. The uninterrupted necessity for anticoagulants is the most important disadvantage. The question of whether patients may profit from the continuous elimination of mediators involved in acute renal or multiple organ failure is still open. In retrospective analysis continuous methods appear to reduce mortality in acute renal failure, but prospective randomized studies are necessary to clearly demonstrate a benefit of these methods as opposed to intermittent haemodialysis.

High Dialysate Flow Rate Continuous Arteriovenous Hemodialysis: A New Approach for the Treatment of Acute Renal Failure and Tumor Lysis Syndrome

A continuous dialysis technique such as continuous arteriovenous hemodialysis (CAVHD) could be an interesting alternative to frequent intermittent hemodialysis to treat acute renal failure (ARF) secondary to tumor lysis syndrome (TLS). However, because of massive release of intracellular solutes in TLS, CAVHD clearances need to be increased to treat this syndrome. Continuous arteriovenous hemodialysis using a high dialysate flow rate at 4 L/hr was assessed in TLS and ARF associated with severe hyperphosphatemia. A 0.6-m2 hollow-fiber polyacrylonitrile dialyzer (Multiflow 60; Hospal, St-Léonard, Québec, Canada) was used. Blood urea nitrogen and serum creatinine levels decreased, respectively, from 102.5 to 27.2 mg/dL and from 3.1 to 1.8 mg/dL during the 36 hours of treatment. Serum urate concentration was normal at the beginning of treatment (4.5 mg/dL) and decreased to 2.1 mg/dL by the end of CAVHD. Serum phosphorus decreased from 16.7 to 4.4 mg/dL after the 36 hours of treatment. The calcium x phosphorus product decreased from 111.1 to 42.1 by 28 hours and remained under 50 thereafter. Serum potassium was easily controlled with the addition of 2.5 mEq/L of KCl in dialysate and replacement solutions. No rebound increases in phosphorus or potassium were noted after cessation of therapy. Continuous arteriovenous hemodialysis clearances of urea, creatinine, phosphorus, and urate were measured at 2-hour intervals for the first 24 hours and at 4-hour intervals for the remaining 12 hours. They were 53.0 +/- 2.3 mL/min, 43.7 +/- 2.2 mL/min, 40.4 +/- 1.9 mL/min, and 39.3 +/- 1.9 mL/min (n = 15), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)