Protocol for the administration of haemofiltration fluids and using patient group electrolytes direction

A patient group direction (PGD) is a specific written instruction for the supply or administration of named medicines in an identified clinical situation The introduction of a PGD must demonstrate a benefit for patients Haemofiltration is widely accepted as the treatment of choice when caring for critically ill patients in acute renal failure on an intensive care unit The haemofiltration PGD improves patient care by providing standardisation in administration of fluids and electrolytes and enabling nurses to respond rapidly to changes in biochemistry during haemofiltration This paper describes the development and implementation of a protocol to enable nurses to administer haemofiltration fluids and electrolytes under a patient group direction.

[Non-biological liver support in hepatic failure]

Liver failure leads to the accumulation of a range of toxins that may be implicated in the development of the multiorgan failure associated with liver failure. A device capable of removing toxins would thus be useful in the treatment of liver failure by stabilising the patient until either the liver begins to regenerate or liver transplantation can take place. A number of non-biological devices based on modifications and combinations of haemodialysis, haemofiltration, haemoperfusion, and plasma separation have been investigated and are reviewed in this article. So far, the most promising results have been demonstrated with devices that remove a wide range of toxins, including those bound to albumin.

Procalcitonin and proinflammatory cytokine clearance during continuous venovenous haemofiltration in septic patients

Procalcitonin (PCT), interleukin-6 (IL-6), tumour necrosis factor a (TNFalpha), and interleukin-1beta (IL-1beta) are important clinical prognostic markers in ICU septic patients. The goal of the study was to determine whether continuous venovenous haemofiltration (CWH), using an AN69 haemofilte, leads to elimination of PCT, TNFalpha, IL-6 and IL-1beta in 13 septic patients with multi-organ failure. At the start of haemofiltration (0), 6 and 12 hours the mean afferent plasma concentration +/- SD of PCT (10.1 +/- 9.1, 7 +/- 6, 5.9 +/- 5.7 ng/ml), IL-6 (804.6 +/- 847.6, 611.7 +/- 528.4, 575.2 +/- 539.2 pg/ml), and that of TNFalpha (4.5 +/- 2.6, 4 +/- 3.1, 3.8 +/- 2.9 pg/ml) significantly declined during CVVH. The efferent plasma concentrations were significantly lower than the corresponding afferent concentrations. PCT; IL-6 and TNFalpha were detectable in the ultrafiltrate of all patients. IL-1beta was only detectable in the plasma of eight patients and the ultrafiltrate of five patients. The plasma clearance of PCT, IL-6 and TNFalpha significantly decreased after 12 hours as a result of a decline in the adsorptive elimination of the mediators due to progressive membrane saturation. We demonstrated that if PCT, IL-6 and TNFalpha are used as clinical prognostic markers in septic patients who are treated with CWIH using an AN69 membrane, one should be aware that their plasma level could be modified by the therapy. In addition CWH could represent an appropriate tool to remove a broad spectrum of proinflammatory mediators, if such removal is required in septic patients.

A pilot study of coupled plasma filtration with adsorption in septic shock

OBJECTIVE

To test the hypothesis that nonselective plasma adsorption by a hydrophobic resin (coupled plasmafiltration and adsorption) could improve hemodynamics and restore leukocyte responsiveness in patients with septic shock.

DESIGN

Prospective, pilot, crossover clinical trial.

SETTING

General intensive care unit in a teaching hospital.

SUBJECTS

Ten patients with hyperdynamic septic shock.

INTERVENTIONS

Patients were randomly allocated to 10 hrs of either coupled plasma filtration adsorption plus hemodialysis (treatment A) or continuous venovenous hemodiafiltration (treatment B) in random order. We measured the change in mean arterial pressure, norepinephrine requirements, and leukocyte tumor necrosis factor-alpha (TNF-alpha) production (both spontaneous and lipopolysaccharide-stimulated) after 10 hrs of each treatment. We also tested TNF-alpha production from normal human adherent monocytes incubated with patients' plasma obtained before and after the resin, both with or without incubation with an anti-interleukin-10 monoclonal antibody.

RESULTS

Mean arterial pressure increased after 10 hr by 11.8 mm Hg with treatment A and by 5.5 mm Hg with treatment B (p =.001). There was an average decrease of norepinephrine requirement of 0.08 microg/kg/min with treatment A and 0.0049 microg/kg/min with treatment B (p =.003). All patients but one survived. Spontaneous and lipopolysaccharide-induced TNF-alpha production from patients' whole blood increased over time with treatment A. This increase was more marked in blood drawn after the device (plasmafiltrate-sorbent plus hemodialyzer) (p =.009). Preresin plasma suppressed lipopolysaccharide-stimulated production of TNF-alpha by 1 x 10(6)cultured adherent monocytes from healthy donors. This suppressive effect was significantly reduced after passage of plasma through the resin (p =.019) and after incubation with anti-interleukin-10 monoclonal antibodies (p =.028).

CONCLUSIONS

In patients with septic shock, coupled plasmafiltration-adsorption combined with hemodialysis was associated with improved hemodynamics compared with continuous venovenous hemodiafiltration. This result might be related to its ability to restore leukocyte responsiveness to lipopolysaccharide. These findings suggest a potential role for blood purification in the treatment of septic shock.

Continuous hemofiltration/hemodiafiltration in critical care

Continuous hemofiltration and continuous hemodiafiltration (CHF/CHDF) were developed as continuous renal replacement therapy for patients with severe conditons and has come to be widely performed mainly in critical care, taking the place of intermittent hemodialysis. The membrane pore size of a hemofilter used for CHF/CHDF allows passage of substances ranging from 30,000 to 50,000 Da, and the method for solute removal in CHF/CHDF employs the principle of convection, which is advantageous for removing middle- to high-molecular-weight substances. As apheresis therapy to remove pathogenic substances in blood, CHF/CHDF is therefore being investigated for its possible effect on various morbid conditions. It has recently been found that CHF/CHDF removes humoral mediators including cytokines, particularly in severe systemic inflammatory response syndromes such as septic shock and severe acute pancreatitis. CHF/CHDF is thus beginning to be performed for the prevention and treatment of organ dysfunction secondary to septic shock, trauma, or acute pancreatitis. CHF/CHDF is also efficacious as artificial liver support in preventing adverse effects caused by plasma exchange (PE) and for continuous removal of hepatic coma-inducing substances. CHF/CHDF is effective for various morbid conditions not only as renal replacement therapy, but also as apheresis therapy and is expected to be applied more widely in critical care in the future.

The comparison of plasma deproteinization methods for the detection of low-molecular-weight metabolites by (1)H nuclear magnetic resonance spectroscopy

Blood plasma is the major vehicle by which metabolites are transported around the body in mammalian species, and chemical analysis of plasma can provide a wealth of information relating to the biochemical status of an individual and is important for diagnostic purposes. However, plasma is very complex in physicochemical terms because it is composed of a range of organic and inorganic constituents with a wide range of molecular weights and chemical classes and this makes analysis non-trivial. It is now well established that high-resolution (1)H NMR spectroscopy of blood plasma provides useful qualitative and quantitative biochemical information relating to metabolic disorders. However, one of the problems encountered in NMR spectroscopic analysis of blood plasma is the extensive peak overlap or presence of broad macromolecule peaks in the (1)H NMR spectrum, which can severely limit the amount of obtainable information. Even with spectroscopic editing, information relating to low-molecular-weight (MW) metabolites is frequently lost. Therefore, the efficiency of a range of conventional protein removal methods, in combination with the use of one- and two-dimensional NMR spectroscopic methods for evaluation, have been compared for the extraction of NMR-observable low-MW metabolites. It has been shown that these "deproteinization" methods vary considerably in recovery of low MW metabolites and a judicious choice is crucial for optimal extraction of a given analyte. The results presented here show that while ultrafiltration provides the "safest" method of plasma deproteinization, the signal-to-noise ratio of the resultant (1)H NMR spectra is poor. On the other hand, acetonitrile precipitation at physiological pH allows the detection of more low-MW metabolites and at higher concentrations than any other method and provides the further advantages of being a rapid and simple procedure.

Continuous haemofiltration in acute renal failure with prostacyclin as the sole anti-haemostatic agent

OBJECTIVE

To investigate the safety and efficacy of a synthetic prostacyclin analogue (epoprostenol) for circuit maintenance during continuous veno-venous haemofiltration (CVVH) in patients with acute renal failure (ARF).

DESIGN

Observational case study.

SETTING

University-affiliated six-bed intermediate renal care unit in a nephrology and internal medicine department of a 1300-bed teaching hospital.

PATIENTS

A consecutive series of critically ill ARF patients in whom prostacyclin was the sole anti-haemostatic agent used for CVVH.

INTERVENTIONS

Bicarbonate-based CVVH in pre-dilution (1.5 l/h); blood flow rate at 200 ml/min; prostacyclin at 4 ng/kg per min infusion in the extracorporeal circuit before the haemofilter.

MEASUREMENTS AND MAIN RESULTS

Fifty-one ARF patients (mean APACHE II 27.2, SD 7.8; acute tubular necrosis in 44/51, 83%; mechanical ventilation 14/51, 21%; in-hospital mortality 28/51, 54%) underwent CVVH for a total of 4040 h (230 circuits, median number 4 circuits per patient, range 1-13). Four patients out of 51 (7.8%) experienced major bleeding during CVVH (1.0 episode per 1000 patient-hours of treatment; 95%CI, 0.4-2.6); no death could be attributed to haemorrhage. Therapeutic intervention for hypotension (fluids and/or vasopressors) was required in 15.5% of the CVVH sessions monitored. The median duration of the circuit was 15.0 h (95% CI, 13.0-16.5).

CONCLUSIONS

The use of prostacyclin as the sole anti-haemostatic agent for CVVH entails a low risk of haemorrhagic complications, while maintaining the patency of the circuit long enough to allow the delivery of an adequate dose of renal replacement therapy. Further studies are needed to compare this technique to other anti-haemostatic strategies for CVVH.

Metabolic replacement of kidney function in uremic animals with a bioartificial kidney containing human cells

Current renal substitution therapy with hemodialysis or hemofiltration has been an important life-sustaining technology, but it still has suboptimal clinical outcomes in patients with end-stage renal disease or acute renal failure. This therapy replaces the small solute clearance function of the glomerulus but does not replace the metabolic and endocrinologic functions of the tubular cells. This article shows that the combination of a synthetic hemofiltration cartridge and a renal tubule cell assist device (RAD) containing human cells in an extracorporeal circuit replaces filtration, metabolic, and endocrinologic functions in acutely uremic dogs. The RAD maintained excellent performance and durability characteristics for 24 hours of continuous use in the uremic animals. The RAD increased ammonia excretion, glutathione metabolism, and 1,25-dihydroxyvitamin D3 production. Cardiovascular stability in the animals was documented in these studies during this extracorporeal treatment. With these results, clinical evaluation of this device in the treatment of severely ill patients with acute renal failure in an intensive care unit has been initiated.

Dialyzer fiber bundle volume and kinetics of solute removal in continuous venovenous hemodialysis

The relationship between dialyzer fiber bundle volume (FBV), dialyzer life span, and small-solute clearance has yet to be clearly defined in continuous venovenous hemodialysis (CVVHD). This study sought to define this relationship using novel ultrasound dilution technology. We studied 55 sessions in 31 intensive care unit patients on CVVHD therapy. A session was defined as the life span of a single dialyzer. The following variables were assessed every 6 hours throughout each session, starting within 1 hour of initiation of that session: FBV, access recirculation, extracorporeal blood flow rate, effluent (EUN) to blood urea nitrogen (BUN) concentration ratio, effluent creatinine to blood creatinine concentration ratio, and urea nitrogen and creatinine clearances. Data were analyzed using random-effects linear models to estimate trends. Several dialysis-related and solute-removal parameters were analyzed for association with each other. Systemic or dialysis circuit heparin was administered in 28 of 55 sessions. One hundred seventy sets of FBV, 101 sets of urea clearance, and 102 sets of creatinine clearance measurements were performed. There was a declining trend for FBV (0.8 mL/h), heart rate (0.25 beats/min/h), and measured blood flow (0.33 mL/min/h; P < 0.05). Apart from dialysate inflow rate (P = 0.044), there was no significant correlation with EUN-BUN ratio. Session duration was associated with dialysis access site; the femoral access provided longer dialysis sessions than subclavian and internal jugular accesses (P = 0.029). We conclude that small-solute removal remains stable over the course of our CVVHD system life spans despite significant loss of hemodialyzer FBV.

Hemofiltration and inflammatory mediators

Hemofiltration used in conjunction with cardiac surgery and cardiopulmonary bypass (CPB) was first reported in 1976. Since then, the technology has been routinely used in this context. This review attempts to restate the basic principles governing hemofiltration, the strategies or timing of the use of the technology, and the indications. Particular attention will be focused on the role of hemofiltration in an attempt to reduce the plasma levels of some of the mediators of the Systemic Inflammatory Response Syndrome (SIRS).

Removal of lepirudin, a recombinant hirudin, by hemodialysis, hemofiltration, or plasmapheresis

Lepirudin (recombinant hirudin), a direct thrombin inhibitor, is an effective alternative method of anticoagulation in patients with heparin-induced thrombocytopenia. However, because it is eliminated by the kidneys, the half-life of lepirudin may be substantially prolonged in patients with renal failure. Patients undergoing hemodialysis must be closely monitored, and therapy must be individualized based on each patient's ability to clear the drug. Current literature on the removal of lepirudin by dialysis or plasmapheresis is limited, but available data suggest that lepirudin can be removed with these methods. The ability of filtration systems to remove lepirudin from the blood is highly dependent on the membrane material used in the system. Understanding the effects of hemodialysis, hemofiltration, and plasmapheresis on lepirudin levels is important, especially since no antidote is available to treat elevated serum lepirudin concentrations.

Citrate anticoagulation in a piglet model of pediatric continuous renal replacement therapy

OBJECTIVE

To develop pediatric guidelines for the use of citrate as a regional anticoagulant for continuous renal replacement therapy (CRRT) using a neonatal piglet model.

DESIGN

Prospective observational study.

SETTING

Animal laboratory in the research center of a tertiary-level children's hospital.

SUBJECTS

Ten neonatal piglets.

INTERVENTIONS AND MEASUREMENTS

Using a venovenous CRRT circuit and filter, we randomly altered the filter blood flow rate, replacement flow rate, and citrate flow rate over conventional pediatric ranges. Measured end points were prefilter serum ionized calcium and citrate levels.

MAIN RESULTS

A prefilter serum citrate concentration of 6 mmol/L is required to maintain the prefilter ionized calcium < or =0.4 mmol/L. Using multiple regression analysis on collected data, we derived a formula to predict prefilter serum citrate for combinations of replacement flow rate, blood flow rate, and citrate flow rate.

CONCLUSIONS

The available literature and our past experience indicate that a prefilter ionized calcium < or =0.4 mmol/L is required to anticoagulate a CRRT circuit; a prefilter serum citrate concentration of 6 mmol/L is required to achieve this. Our multiple regression analysis can be expressed graphically to allow easy calculation of the required citrate flow rate, given the knowledge of the replacement flow rate and blood flow rate. Our results provide the first guidelines for the use of citrate as a regional anticoagulant in a pediatric-size model of CRRT.

Sustained benefit from ultrafiltration in moderate congestive heart failure

Body fluids, particularly in the thorax, are increased in moderate congestive heart failure, even if diuretic treatment is appropriate. Ultrafiltration, differently from diuretics, removes isotonic fluid and therefore the greatest possible amount of sodium per unit of fluid withdrawn, providing a physiologic dehydration. This results in improvement in the patient's clinical condition, exercise capacity, lung function, as shown by improvement of standard pulmonary function tests, lung mechanics during exercise, and norepinephrine kinetics during exercise and orthostatic tilting.

Clinical benefit and approach of ultrafiltration in acute heart failure

Because of the increasing incidence of acute heart failure admissions to critical care units, nephrologists have been asked to become more involved in the management of these patients. Renal dysfunction is a major element in impeding clinical recovery. In acute heart failure, renal function is often abnormal. The judicious application of ultrafiltration techniques may represent an efficacious adjunct to present conventional practice. In patients with refractory congestive heart failure, the ability to provide continuous, daily, large volume removal not only improves volume status but also the clinical symptoms of the decompensated patient. A thorough literature review supports the premise that starting hemofiltration is an appropriate alternative for difficult and unstable cardiac patients. An optimal strategy utilizing continuous renal replacement therapy can dramatically improve the patient's clinical condition, mitigate the neurohumoral stimulation, increase urinary output and promote absorption of excessive extravascular fluid.

Intensive care unit management of the critically ill patient with fluid overload after open heart surgery

Fluid overload is common before, during and after cardiac surgery. The fluid associated with cardiopulmonary bypass (CPB) and cardioplegia is a particularly important source of such fluid overload. In addition, renal dysfunction, which is common in these patients, participates in the pathogenesis of a positive sodium and water balance. Such fluid overload is physiologically undesirable and participates in the pathogenesis of several clinically important complications. Fluid overload can be partly prevented with the use of diuretics. However, in many patients, diuretics do not achieve sufficient sodium and water diuresis. In these patients, the application of hemofiltration (HF) during CPB and also immediately after CPB is an effective and safe approach to the maintenance of fluid homeostasis. If acute renal failure occurs, early intervention with HF may even improve survival.

Extracorporeal ultrafiltration for the treatment of overhydration and congestive heart failure

Fluid overload may occur in patients with congestive heart failure. Under normal conditions, this is treated with inotropic support and diuretics. However, when diuretics fail, fluid removal becomes uncontrolled and other therapeutic options must be undertaken. Extracorporeal ultrafiltration is a possible solution to restore a status of fluid balance close to normal. Several new technologies have made ultrafiltration available today in all centers and easy to be instituted. Acute isolated schedules of ultrafiltration may, however, be too aggressive and result in severe hemodynamic instability. For this reason, continuous extracorporeal techniques have been applied in such patients and the therapy is generally carried out with success. Excellent hemodynamic stability, a good cardiovascular response and often diuresis restoration are the most common effects encountered using continuous forms of extracorporeal fluid removal. The potential for a home-based application of these techniques represents a further stimulating concept to be investigated.

Continuous veno-venous hemofiltration improves hemodynamics in septic shock with acute renal failure without modifying TNFalpha and IL6 plasma concentrations

BACKGROUND

Continuous hemofiltration improves hemodynamics in critically ill patients by removing cytokines from the plasma. The mechanism, however, remains to be clarified since recent studies show conflicting findings. The present study was therefore designed to evaluate hemodynamic changes and kinetics of tumor necrosis factor (TNF)alpha, interleukin (IL)1beta and IL6 in patients with septic shock and acute renal failure (ARF) undergoing continuous veno-venous hemofiltration (CWHF), over a 24-hour period.

METHODS

Eleven patients admitted to the ICU for septic shock with ARF were investigated with radial artery and pulmonary artery catheterization during isovolemic CWHF using AN69 hemofilters at a blood flow rate of 240 mL/min and ultrafiltration 1.65 +/- 0.33 L/h. Hemodynamic measurements (mean arterial pressure, right arterial pressure, pulmonary artery pressure, pulmonary vascular resistance, systemic vascular resistance, cardiac output and tissue oxygenation indeces) were obtained before and after 2h, 4h, 6h, 12h and 24 h of CVVHF. Blood samples from the pre- and postfilter lines and ultrafiltrate samples were collected for the radioimmunoassay of TNFalpha, IL1beta and IL6 before and at 2h, 4h, 6h, 12h and 24h.

RESULTS

During CVVHF, mean arterial pressure rose from 67 +/- 7 mm Hg to 89 +/- 5 mm Hg (p < 0.05) and indexed systemic vascular resistance from 711 +/- 153 dyne.s.cm(-5)/m2 to 1,200 +/- 100 dyne.s.cm(-5)/m2 (p < 0.05). Serum lactate and oxygen consumption did not change. Mean arterial pressure and systemic vascular resistance were not correlated to the lowering of body temperature during CVVHF. Significant clearance of IL6 was achieved, but not of TNFa, though the plasma concentrations of both cytokines were unaffected throughout the study. IL1beta was not detectable. Two patients were discharged alive with normal renal function.

CONCLUSION

In patients with septic shock and ARF, CVVHF improves mean arterial pressure and systemic vascular resistance. This effect does not appear to be related to the removal of cytokines. The effect of CVVHF on mortality and morbidity in the long term, in septic shock has still to be established.

Inflammatory mediator removal by zero-balance ultrafiltration during cardiopulmonary bypass

The abnormal conditions to which blood is subjected during cardiopulmonary bypass (CPB) trigger an activation of the inflammatory response in all patients to varying degrees. Both complement activation and the release of cytokines characterize this response. Most inflammatory mediators have a molecular weight that is below the membrane pore size of commonly used ultrafilters, which should allow them to be freely filtered. However, some mediators have been shown to fail to cross through the membrane even though they are small enough to cross. The purpose of the present study was to determine whether certain inflammatory mediators could be removed by ultrafiltration when performed during the rewarming phase of CPB. Thirty adult patients undergoing a single, open-heart procedure were randomized to either control (no ultrafiltration) or to the zero-balance ultrafiltration (ZBUF) group. ZBUF was performed by removing 3 l/m2 blood using a 65-kDa ultrafilter with 1.3-m2 surface area. A volume of a balanced salt crystalloid solution (Plasmalyte) equal to the filtered blood volume was given to replace the fluid removed. Patient data was taken before CPB (T1), immediately following CPB (T2), and 12 h following the procedure (T3). The average volume of filtrate removed during ZBUF was 6405 ml, which was analyzed for the presence of interleukin (IL)-1, IL-6, tumor necrosis factor-alpha (TNF-alpha), C3a, and C5a. The average concentrations of the mediators measured in the effluent were: IL-1, 0.17 pg/ml; IL-6, 0.64 pg/ml; TNF-alpha, 1.25 ng/ml; C3a, 782.6 ng/ml; C5a, 25.6 ng/ml. In every case except for IL-1, the amounts of mediators removed were significantly greater than zero. This study demonstrates that ultrafiltration is a strategy that can be used during CPB in the adult to remove significant amounts of inflammatory mediators.

Pharmacokinetics of levofloxacin during continuous venovenous hemodiafiltration and continuous venovenous hemofiltration in critically ill patients

STUDY OBJECTIVE

To assess the pharmacokinetics of levofloxacin during continuous venovenous hemodiafiltration (CVVHDF) and continuous venovenous hemofiltration (CVVH).

DESIGN

Nonrandomized pharmacokinetic evaluation.

SETTING

University surgical intensive care unit.

PATIENTS

Six critically ill patients.

INTERVENTION

Five patients received levofloxacin 500 mg/day and one patient received levofloxacin 125 mg/day All patients received continuous renal replacement therapy: CVVHDF on day 1 and CVVH on day 2, using an acrylonitrile hollow-fiber 0.9-m2 filter, constant blood flow rate of 90 ml/minute, substitution flow rate of 1 L/hour predilution, and dialysate flow rate of 1 L/hour (CVVHDF).

MEASUREMENTS AND MAIN RESULTS

Serum, ultrafiltrate, and dialysate concentrations of levofloxacin were determined by high-performance liquid chromatography. Extracorporeal clearance was 26.05 +/- 4.66 ml/hour during CVVHDF and 15.71 +/- 2.73 ml/hour during CVVH (p<0.05). Elimination half-life was 28.08 +/- 4.5 hours and 45.9 +/- 17.7 hours, and distribution volume was 1.51 +/- 0.52 L/kg and 1.42 +/- 0.42 L/kg for CVVHDF and CVVH, respectively. Saturation was 0.76 +/- 0.13 for CVVHDF versus a sieving coefficient of 0.77 +/- 0.16 for CVVH.

CONCLUSION

Marked extracorporeal elimination of levofloxacin occurs, requiring a dosage adjustment that can be calculated from the characteristics of CVVH and CVVHDF.

Quality control of leucoreduced cellular blood components in France

BACKGROUND AND OBJECTIVES

Since 1 April 1998, all cellular blood components in France have been leucoreduced. The current French standard is < 1 x 10(6) white blood cells (WBC) per unit with a 95% confidence that at least 97% of units will meet this standard.

MATERIALS AND METHODS

Quality control (QC) data for leucoreduced cellular blood components were collected from the 41 French blood centres over a 5-month period. Conformance to the standard was determined using a non-parametric approach.

RESULTS

More than 98% of the 15 286 red cell concentrates and of the 2895 platelet concentrates tested had < 1 x 10(6) WBC per unit. One filtration device gave unsatisfactory results and its use was discontinued.

CONCLUSION

This QC survey shows an overall compliance with the standard. The data illustrate the practical value of identifying devices or centres with consistent QC problems.

Clearance of ceftazidime during continuous venovenous haemofiltration in critically ill patients

Published recommendations for the optimal dosing regimen of ceftazidime in critically ill patients with continuous venovenous haemofiltration (CVVH) differ. The aim of this prospective study was to analyse the pharmacokinetic and pharmacodynamic parameters of ceftazidime during CVVH with a high-flux polysulphone membrane, and derive a dosage recommendation. Twelve critically ill patients (five female, seven male) with acute renal failure undergoing CVVH using a 0.7 m(2) polysulphone high-flux membrane were investigated. All patients received ceftazidime 2 g i.v. q8h. Peak ceftazidime concentrations were 58.2 +/- 11.6 mg/L, with trough concentrations 14.0 +/- 3.2 mg/L at the arterial port. The elimination half-life, haemofiltration clearance, volume of distribution and total removal were 4.3 +/- 0.6 h, 32.1 +/- 7.9 mL/min, 36.4 +/- 6.4 L and 74.5 +/- 6.5%, respectively. Based on these pharmacokinetic parameters and that maximal killing is at 4 x MIC we recommend at least ceftazidime 2 g i.v. q8h.

Pro/con clinical debate: is high-volume hemofiltration beneficial in the treatment of septic shock?

Although there have been exciting advances in the management of sepsis and septic shock, mortality still remains high. Recent data suggest that high-volume hemofiltration (HVHF) may play a role in these patients. In contrast to the usual rate of hemofiltration, HVHF is felt to be better able to remove the inflammatory mediators associated with sepsis and septic shock. Such an approach is currently incapable of selectively removing specific mediators. This may be a problem when one considers that several mediators may in fact be beneficial. When determining whether HVHF should be instituted in a patient with septic shock, one need remember that its role is far from clear and its usefulness remains the subject of much debate. Although early data is encouraging, it is clear that additional data is required before HVHF becomes standard management. The authors of this pro/con debate, which is based on a clinical scenario, first describe their own position and then respond to their opponent's position.