Continuous Arteriovenous Hemofiltration Research Articles

Effect of Continuous Arteriovenous Haemofiltration on Pharmacokinetics of Amrinone

This case report details the pharmacokinetic adjustments of an amrinone infusion in a paediatric patient who developed multiorgan system failure with anuric renal failure and was prescribed continuous arteriovenous haemofiltration. A significant proportion of clearance of amrinone is nonrenal. Near normal amrinone clearance can occur in patients with hepatic and renal dysfunction if continuous arteriovenous haemofiltration is used. Hepatic dysfunction with renal failure may require a reduction in the continuous amrinone infusion rate as previously reported for neonates.

Maximum Ultrafiltration Rate in Continuous Arteriovenous Hemofiltration Does Not Occur at the Lowest Level of the Ultrafiltrate Collection Chamber

A common assumption is that increasing transmembrane pressure by lowering the ultrafiltrate receptacle and the accompanying fluid column should always result in increasing ultrafiltration in continuous arteriovenous hemofiltration (CAVH) systems. To test this assumption, CAVH circuits were operated in vitro with use of a recirculating apparatus with an adjustable elevated reservoir. Hydraulic operational characteristics were studied in a variety of CAVH circuits, lowering the height of the ultrafiltrate column stepwise until it was at the lowest height possible. The results for most experiments performed reveal that ultrafiltration rate (UFR) reaches a peak and then declines as the collection receptacle is lowered further. There is also a decline in pre-filter blood flow preceding the peak in UFR. At lower blood flow, UFR decreases for the same transmembrane pressure (TMP). Therefore, as ultrafiltrate pressure is decreased, the effect of increased TMP on UFR is opposed by the effect of decreased blood flow, which decreases UFR. The implication of this in clinical medicine is that one may need to empirically test UFR in a CAVH system in positions other than the very lowest position.

Maximum Ultrafiltration Rate in Continuous Arteriovenous Hemofiltration Does Not Occur at the Lowest Level of the Ultrafiltrate Collection Chamber

Maximum Ultrafiltration Rate in Continuous Arteriovenous Hemofiltration Does Not Occur at the Lowest Level of the Ultrafiltrate Collection Chamber

A Comparison of Continuous Arteriovenous Hemofiltration and Intermittent Hemodialysis in Acute Renal Failure Patients in the Intensive Care Unit

Our experience with high flow CAVH (1-2 L/hr) and intermittent hemodialysis in our combined medical-surgical tertiary care intensive care unit was reviewed. During a 16 month period, 12 patients received CAVH and 23 patients received hemodialysis (3-7 days/week). Mean CAVH treatment duration was 5.5 days (0.5-18 days). Hemodialysis patients received a mean of 4.3 treatments (1-16). CAVH patients had a mean age of 44.5 +/- 16.4 years (19-68), whereas the hemodialysis patients had a mean age of 60.9 +/- 14 years (34-82) (p = 0.004). Mean admission APACHE II score was 21.3 (11-29) for the CAVH group and 25.5 (10-39) for the hemodialysis group (p = NS). Peak ICU APACHE II score did not differ between groups (CAVH 26.2 [11-37], HD 28 [10-40]; p = NS). There were 4 deaths in the CAVH group (25%) and 19 deaths in the HD group (82%) (p = 0.006: chi-squared test). Although age was significantly different between groups, APACHE II scores were similar. Mortality rate was significantly higher in the hemodialysis group. This supports the hypothesis that CAVH may be the renal replacement therapy of choice in the ICU.

A Comparison of Continuous Arteriovenous Hemofiltration and Intermittent Hemodialysis in Acute Renal Failure Patients in the Intensive Care Unit

A Comparison of Continuous Arteriovenous Hemofiltration and Intermittent Hemodialysis in Acute Renal Failure Patients in the Intensive Care Unit

Continuous arteriovenous hemofiltration therapy for Staphylococcus aureus-induced septicemia in immature swine.

The goals of this study were: a) to evaluate the efficacy of controlled, continuous arteriovenous hemofiltration in improving morbidity and mortality rates in an immature swine model of Staphylococcus aureus-induced septicemia; b) to determine if ultrafiltrate from septic animals contained mediators that produce pathophysiologic changes observed in untreated S. aureus septic pigs. Prospective, randomized, controlled study with age-matched controls. U.S. Department of Agriculture-licensed biomedical research facility. Sixty-five weaned Poland-China swine (4 to 6 wks of age; 5 to 10 kg). Part 1: Animals received a lethal dose of live S. aureus (8 x 10(9) colony-forming units/kg) over 1 hr. The three treatment groups included: hemofiltration group 1 (eight filtered, eight nonfiltered animals), plasma filtration fraction = 5.5%; hemofiltration group 2 (six filtered, six nonfiltered animals), filtration fraction = 16.6%; and hemofiltration group 3 (six filtered, six nonfiltered animals), filtration fraction = 33.4%. A control, nonseptic group of animals (n = 4) was filtered to obtain "clean" ultrafiltrate (hemofiltration group 4). Part 2: Sterile ultrafiltrate concentrate batches obtained from each group of filtered, septic animals were concentrated and infused into healthy, nonseptic pigs (reinfusion groups 1 through 3). Physiologic, biochemical, and hematologic variables were measured in all animals every 1 to 3 hrs. Overall length of survival was also recorded. In hemofiltration groups 1 through 3, filtered animals survived significantly longer than matched, nonfiltered (sham-filtered) animals. Increments in survival time increased directly with filtration fraction. Ultrafiltrate concentrate from septic pigs produced death (LD41) and disease similar to those rates observed in untreated S. aureus-septic pigs. Infusion of clean ultrafiltrate concentrate produced no response. Continuous arteriovenous hemofiltration significantly improved survival rates in swine with S. aureus-induced sepsis. Resultant ultrafiltrate concentrate contained mediators responsible for some pathophysiologic responses observed in this animal model.

Operating characteristics of pediatric continuous arteriovenous hemofiltration in an animal model

Continuous arteriovenous hemofiltration (CAVH) is an increasingly popular technique in the care of critically ill children. The operating characteristics of the available circuits are largely unknown. Prior to introducing CAVH into our pediatric intensive care unit, we investigated the performance of three CAVH circuits: CAVH with postfilter dilution, CAVH with prefilter dilution (CAVHpre) and CAVH with dialysis counterflow. Using a neonatal lamb model, we measured filter blood flow (QB), ultrafiltrate rate (QU), arterial, venous and ultrafiltrate compartment pressures, oncotic pressure, plus urea levels in blood and ultrafiltrate fluid for the three CAVH circuit designs. Transmembrane pressure and urea clearance were calculated for various values of QB after varying a clamp on the arterial side of the circuit. The major finding, applicable to all circuits, was the wide variability of QB. Constant attention was required in order to obtain a consistent QB. Fluid clearance was effective with all three circuits. Urea clearance averaged 5-10 ml/min and was principally dependent on QU and independent of QB. The addition of dialysis counterflow did not increase urea clearance. The most convenient circuit we tested was CAVHpre, but the problem of unstable QB is common to all unpumped arteriovenous filtrate circuits. It is a major limiting factor in the practical application of this technology to critically ill children.

Protein catabolic rate in patients with acute renal failure on continuous arteriovenous hemofiltration and total parenteral nutrition.

Continuous arteriovenous hemofiltration (CAVH) has been used to provide nutrition support to critically ill patients in acute renal failure (ARF). Limited information exists regarding protein needs of these patients. Nineteen postoperative patients in ARF and on CAVH and total parenteral nutrition (TPN) were studied (10 men; 9 women; mean age, 65 yr) to determine protein needs (protein catabolic rate; PCR), urea nitrogen appearance (UNA), and total nitrogen appearance (TNA). TPN was adjusted to meet the needs estimated by the Harris-Benedict and Long equations. A total of 38 24-h studies were conducted on the 19 subjects. TNA, UNA, and PCR were determined by direct measurement of body losses and calculation of body pool nitrogen changes. Patients received an average of 93.9 +/- 30.5 g of protein (1.4 g/kg) and 2,600 +/- 534 kcal/day in TPN. Mean PCR was 117.5 +/- 42.8 g/day; UNA was 18.3 +/- 6.9 g/day. TNA and UNA were strongly correlated (r = 0.99; P < 0.001). PCR was less strongly correlated with estimated protein needs (r = 0.35; P = 0.03). A regression equation was developed describing the relationship between TNA and UNA as follows: TNA = 1.895 + 0.9444 (UNA) or UNA = 0.1602 (PCR) - 0.916. On the basis of this study, CAVH permits the provision of adequate nutrition support to critically ill, unstable patients. It appears that the protein needs of patients in ARF on CAVH can be accurately estimated by determining UNA through the measurement of urea losses and urea body pool changes and by regression equations to calculate PCR.(ABSTRACT TRUNCATED AT 250 WORDS)

実験的急性腎不全犬におけるContinuous Arteriovenous Hemofiltrationの効果

The efficacy of continuous arteriovenous hemofiltration (CAVH) as hemocatharsis and its influences on the hemodynamics were examined in dogs with experimentally induced acute renal failure. The mongrel dogs with acute renal failure induced by the ligation of the renal arteries, renal veins and ureters for 24 hr were adopted in this study. The concentrations of blood urea nitrogen and serum creatinine gradually increased in the five non-treated dogs. The concentrations in the five dogs treated with CAVH for 24 hr did not show a continuous increase. The hemodynamic changes were negligible in the dogs during CAVH. These results suggested that the CAVH is applicable as a technique for hemocatharsis in canine acute renal failure.

Continuous arteriovenous hemofiltration after cardiac operations in infants and children

Acute renal insufficiency after cardiopulmonary bypass can lead to a significant morbidity from fluid overload and electrolyte disturbance, impede pulmonary gas exchange, and postpone weaning from mechanical ventilation. The limitations placed on free water intake result in severe restriction of nutrition while diuretic therapy causes electrolyte imbalance. Artificial renal support either in the form of peritoneal dialysis or hemodialysis may be complicated by sepsis and hemodynamic instability. We reviewed our experience with the use of continuous arteriovenous hemofiltration, an extracorporeal technique for removal of solutes, toxins, and water in critically ill patients with cardiac failure complicated by acute renal insufficiency and hemodynamic instability after cardiopulmonary bypass. Ten infants and children with renal insufficiency caused by low cardiac output had continuous arteriovenous hemofiltration instituted for indications including sepsis, volume overload, oliguria for more than 24 hours nonresponsive to diuretic therapy, and the need for hyperalimentation. All were supported by mechanical ventilation and receiving high-dose inotropic support. Arterial and venous vascular access was successfully obtained by cannulation of the femoral artery and vein in nine patients. Anticoagulation of the circuit was achieved with heparin infusion (6 to 20 micrograms/kg/hr) and monitored by measurement of activated clotting time. The continuous arteriovenous hemofiltration circuit was replaced if there was clot formation, or at 3 days after placement. Dialysis solution (Dianeal) 1.5% or 0.5% was infused as prefilter dilution. With the use of continuous arteriovenous hemofiltration, 20 to 100 m/hr of ultrafiltrate was removed, which allowed correction of hypervolemia, and caloric intake increased from 13.5 kcal/kg/day to 79.5 kcal/kg/day. Continuous arteriovenous hemofiltration was maintained between 5 hours and 8 days and was well tolerated in all patients. Serum urea and creatinine levels declined during continuous arteriovenous hemofiltration. We conclude that continuous arteriovenous hemofiltration is a safe and effective method for fluid and electrolyte homeostasis and that it thus allows hyperalimentation in infants and children after cardiac operations.

When to Use Continuous Therapy: Continuous Arteriovenous Hemofiltration (CAVH) or Continuous Venovenous Hemofiltration (CVVH)

When to Use Continuous Therapy: Continuous Arteriovenous Hemofiltration (CAVH) or Continuous Venovenous Hemofiltration (CVVH)

Preventing complications in the CAVH patient.

Continuous arteriovenous hemofiltration (CAVH) is a recently developed extracorporeal technique for treating the fluid overloaded, critically ill patient. Severe complications can occur during this procedure, including clotting and malfunction of the filter, exsanguination, or fluid and electrolyte imbalance. The critical care nurse who understands the principles of filtration, the concepts of heparinization, and the care and maintenance of the large invasive lines required for CAVH can frequently prevent these complications.

Non-thrombogenic hemofiltration system for acute renal failure treatment.

Continuous arteriovenous hemofiltration (CAVH) has become an accepted therapy for patients with acute renal failure. A major technical concern with CAVH is clotting of the hemofilter, resulting from blood-material interactions. This study compares the thromboresistance and performance characteristics of a Duraflo II heparin treated CAVH circuit with those of an untreated control circuit. The circuit consisted of a polysulfone hemofilter, tubing sets, and catheters. The heparin treatment did not change the mass transfer properties of the hemofilter. The thromboresistance of the heparin treated circuit was compared directly with that of an untreated circuit in a heparinless sheep model using bilateral circuits. The heparin treatment significantly enhanced the blood compatibility of the circuit, as indicated by the reduction in thrombus formation, prolonged work life, and superior performance in heparinless sheep. There was minimal heparin leaching from the hemo-filter. A heparin treated circuit may improve the safety and effectiveness of the CAVH procedure, and offers potential for a systemic heparin protocol to be modified for patients with bleeding disorders.

Full Protein Alimentation and Nitrogen Equilibrium in a Renal Failure Patient Treated With Continuous Hemodiafiltration: A Case Report of 67 Days of Continuous Hemodiafiltration

Standard care for patients with renal failure while in an intensive care unit involves traditional hemodialysis or peritoneal dialysis and protein restriction. We present a case of a patient with renal failure supported with continuous arteriovenous hemofiltration with dialysis (CAVH-D) who was given full protein alimentation. Total daily urea clearance was measured from the CAVH-D output. Protein load was 196 +/- 34 g/day while receiving total parenteral nutrition and 164 +/- 30 g/day while receiving enteral alimentation. Serum blood urea nitrogen was controlled between 40 and 75 mg/dL, except during septic episodes. Nitrogen balance was estimated based upon known alimentation protein load and measurable and estimated nitrogenous losses. The patient was potentially in nitrogen equilibrium during most of the dialysis period. The cumulative nitrogen balance was positive by 5.2 g after 67 days of dialysis. Volume of alimentation was 3.49 +/- 0.7 liters/day. With CAVH-D, the renal failure patient can receive full alimentation without volume or protein load limitations. Furthermore, nitrogen balances can be estimated easily while the patient is on CAVH-D.

Intermittent venovenous hemofiltration as a chronic treatment for refractory and intractable heart failure.

Chronic heart failure (HF) is considered to be refractory when persisting despite an intensive drug regimen, or intractable when requiring "artificial" supports. Among them, hemofiltration (HE) has been used frequently, but only on an "acute" basis, to induce fast and safe water removal. Since 1985 the authors have treated refractory and intractable HF first by means of acute CAVH (continuous arteriovenous HE: 11 patients) and then (1988-1992) with IVVH (intermittent venovenous HE), initially done on an "acute" basis (13 patients) and then an a chronic basis (CIVVH): 8 subjects (6M, 2F; mean age, 60.8 years), 3 with RCHF and 5 with ICHF. This report deals with our experience in CIVVH. All patients were in severe failure. During a follow-up period of 63 months (range, 1-17/patient), 82 IVVH treatments (10.2/patient) were carried out, using this schedule: permanent Tesio catheter in superior vena cava, 0.6 m2 filter, double blood pump (blood flow = 80-250 ml/min); transmembrane pressure = 50-150 mmHg; mean ultrafiltration = 19 ml/min; replacement fluid = 8.6 ml/min; and session time = 340 +/- 88 min, according to individual dry weight (bioimpedance system). Six patients died (1-13 months after IVVH began); four of six had ICHF and two of six had RCHF; five of eight patients showed a significant amelioration of functional state, changing from fourth to third, to second and first degree failure, but this was after heart transplantation. In all cases a marked reduction in the drug regimen and in hospitalization was the rule.

Continuous arteriovenous haemofiltration and respiratory function in multiple organ systems failure.

To determine what change in respiratory function occurred following prolonged and efficient continuous arteriovenous haemofiltration (CAVH) in a group of patients with multiple organ systems failure (MOSF). A retrospective assessment using patient notes and ICU charts. The Intensive Care Unit of a large University Teaching Hospital. All ICU patients satisfying the following criteria: (i) Failure of more than one organ system; (ii) Treatment with CAVH; (iii) Removal of more than 10 l of ultrafiltrate per day; (iv) Continuous haemofiltration for at least 5 days. Thirteen patients satisfied these criteria and 14 episodes of CAVH were analyzed. All data were recorded from the patient notes and ICU charts apart from the A-aDO2 and PaO2/FiO2 (PF) ratio which were calculated from available values. A mean of 3.5 different organ systems failed during the period of stay. The mean daily ultrafiltrate volume obtained was 23.7 (SD 0.95) l and the mean duration of treatment 9.6 (SD 4.3) days. Significant improvements occurred in the values for the PF ratio and ventilatory modality (p < 0.05), and the FiO2 and A-aDO2 (p = 0.001). The mean PEEP value remained unchanged at 4.8 cmH2O. Ten of the 13 patients subsequently died (77% mortality). A significant improvement in respiratory function occurred in patients with MOSF who had undergone a prolonged period of intensive CAVH. Haemofiltration may therefore be a useful treatment for respiratory failure in this patient group. Unfortunately the overall mortality of the group remained high.

Clearance of imipenem/cilastatin in acute renal failure patients treated by continuous hemodiafiltration (CAVHD).

In patients with acute renal failure, who were treated with continuous arteriovenous hemofiltration (CAVH) or continuous arteriovenous hemodiafiltration (CAVHD), we measured clearance rates of imipenem and cilastatin (Tiënam-500). Literature data on volume of distribution and on the endogenous clearance in normals and in anuric patients and the observed clearance rates by CAVH/CAVHD were used to develop guidelines for dose adaptations. Based on the desired peak levels of imipenem, normal subjects should receive the fixed imipenem/cilastatin dose combination (500 mg/500 mg) q.i.d. and patients with acute renal failure should receive the same dose b.i.d. After starting treatment with either CAVH, CAVHD or continuous venovenous hemofiltration (CVVH), no further dose adjustment is necessary. The non-renal clearance rate of cilastatin is very low compared to that of imipenem. If a patient develops anuria, the clearance rate of imipenem decreases from the normal value of 245 ml/min to 116 ml/min. Clearance rate of cilastatin, however, decreases from 230 ml/min to 3 ml/min. Therefore, in patients with renal failure accumulation of cilastatin will occur. On the other hand, if the patient is treated by CAVHD, the relative contribution of the dialyser clearance to the total drug clearance is much greater for cilastatin than for imipenem. As a result, the accumulation of cilastatin is reversed. During treatment by CAVHD, the clearance rate of imipenem raises 15%-25% and that of cilastatin 335%-600%. For this reason, we conclude that the use of the fixed dose combination (500 mg/500 mg) b.i.d. in patients with acute renal failure treated by CAVHD may be justified.

The intensive care unit in paediatric oncology.

There were 70 admissions from a regional paediatric oncology centre to the intensive care unit over a six and a half year period. Patients were divided into those with systemic infections (n = 19), respiratory infections (n = 15), metabolic effects (n = 9), tumour mass effects (n = 10), neurological complications (n = 8), and others (n = 9). The overall survival was 51%. Patients admitted with metabolic or tumour mass related effects had the best prognosis with a survival of 84%. If dialysis is required in this group of patients then continuous arteriovenous haemofiltration is recommended. Patients with systemic or respiratory infections comprised the main poor prognosis group with a survival of 26%. For patients with a systemic infection who required ventilation, the mortality was 100%. The outlook for patients with a generalised encephalopathy was also poor, with no neurologically intact survivors. The median APACHE-II (acute physiology and chronic health evaluation) score for patients who died was 27 and for survivors was 16. There is a need for close cooperation between staff of intensive care and paediatric oncology units. Alternative treatments should be considered for patients with systemic infections who require ventilation.

Acute Renal Failure in the Neonate

Acute renal failure is a common occurrence in the neonatal intensive care unit. This article summarizes pathophysiology, causes, differential diagnosis, methods of prevention, management, and outcome of acute renal failure in the neonate. Comparative roles of continuous arteriovenous hemofiltration and peritoneal dialysis are discussed.

Continuous arteriovenous hemofiltration in the elderly patients

The outcome of continuous arteriovenous hemofiltration (CAVH) treatment was evaluated in fifty one critically ill elderly with acute renal failure (ARF). They were admitted into our University Hospital's intensive-care units (ICU) during January 1987 and December 1990. Mean age (± SD) was 70.7 ± 5 (range 65–84) years. Elderly patients (>65 years old) comprised 44% of the ICU-ARF patients. The causes of ARF were cardiac surgery (41%), medical (31%), aneurysm of the resection of abdominal aorta (20%), and general surgery (8%). In the majority of the patients ARF was complicated by multiple organ failure. A survival of 60% was obtained with CAVH treatment. The highest survival rate (69%) was noted among cardiac surgery ARF patients, while the lowest survival (25%) was seen among patients with ARF following aneurysm of the resection of abdominal aorta. From the results of this study we conclude that CAVH serves a benificial role if it is considered in the management of ARF in the elderly intensive care patients with multiple organ failure.