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R Bellomo

Publications and source records attributed to R Bellomo.

At least 145 records · Page 8Linked to original sources
PubMed1999

New perspectives in the treatment of acute renal failure.

The evolution of technology and biomaterials has permitted a parallel development of renal replacement therapies in the acute, critically ill patient. From the original description of continuous arterio-venous haemofiltration, new techniques such as continuous veno-venous haemofiltration, haemodiafiltration and high flux dialysis have been developed and clinically utilised. A parallel improvement in efficiency has been achieved with urea daily clearances as high as 50 litres or more. The use of special highly permeable dialysers has also permitted to increase the clearances of larger solutes thus leading to significant removals of chemical substances involved in the acute inflammation and sepsis. In this field, recent observations have suggested to use haemofiltration with high volumes of fluid exchange. The hardware and software of the newer continuous renal replacement therapies (CRRT) are certainly the key point in achieving these results and in safely performing such challenging techniques.

Acute Kidney Injury↗
PubMed1999

Effects of norepinephrine on the renal vasculature in normal and endotoxemic dogs.

Septic shock is often complicated by systemic hypotension despite normal or increased cardiac output. Restoration of arterial pressure usually requires the administration of systemic vasopressor agents, such as norepinephrine. However, because norepinephrine induces vasoconstriction in other vascular beds, it may decrease visceral blood flow, impairing visceral organ function. Because sepsis is often associated with impaired peripheral vascular responsiveness, we hypothesized that, unlike in normal circulatory conditions, norepinephrine would improve visceral organ blood flow in sepsis by selectively increasing organ perfusion pressure. Thus, in nine pentobarbital-anesthetized, mechanically ventilated dogs, we measured the effect of norepinephrine infusion (0.3 microgram/kg/min) on renal, hepatic, and portal steady-state pressure-flow relations (P/Q) and the dynamic vascular P/Q, created by transient inferior vena caval occlusion, under basal and endotoxic conditions. Norepinephrine increased organ perfusion pressures during both control and endotoxemic conditions. However, even after controlling for the pressure effect using a general linear model, NE was associated with an increase in renal blood flow both before and after endotoxin administration. We conclude that, unlike the effects of administering norepinephrine under baseline conditions, norepinephrine infusion during endotoxic shock actually increases renal blood flow and that this effect is not the result of an increase in perfusion pressure alone.

Animals↗
PubMed1999

Changing acute renal failure treatment from intermittent hemodialysis to continuous hemofiltration: impact on azotemic control.

BACKGROUND: Continuous renal replacement therapy is increasingly used in the management of acute renal failure in critically ill patients. The advantages of continuous renal replacement therapy (CRRT) over intermittent hemodialysis (IHD), however, are not yet fully documented. In particular, it is unknown whether continuous veno-venous hemodiafiltration (CVVHDF) provides better control of azotemia than IHD. OBJECTIVES: To study the effect on azotemic control of changing acute renal failure treatment from IHD to CVVHDF. SETTINGS: Tertiary intensive care unit. PATIENTS: Forty seven consecutive critically ill patients with multiorgan failure and acute renal failure treated with IHD and 47 similar patients treated with CVVHDF. METHODS: Analysis of daily morning urea and creatinine concentrations over the period of renal replacement therapy in the ICU. Statistical comparison of data. RESULTS: The two groups of patients were comparable for mean age (55 years for IHD vs. 60 years for CVVHDF; NS) and number of failing organs prior to therapy (mean of 4.2 for IHD vs. 3.7 for CVVHDF; NS). Severity of illness at admission as assessed by APACHE II score, however, was greater for patients receiving CVVHDF (29.4 vs 25.7; p<0.003). CVVHDF was associated with a significantly lower plasma urea (p < 0.0001) and serum creatinine (p < 0.01) level at 24 hours of treatment despite similar levels at the start of therapy Throughout the duration of therapy, mean urea levels (35.0 mmol/L for IHD vs 23.4 mmol/L for CVVHDF) and mean serum creatinine levels (513 micromoles/L for IHD and 263 micromoles/L for CVVHDF) showed significantly (p <0.0001) better control of uremia with CRRT. CONCLUSIONS: Changing the form of renal replacement therapy from intermittent hemodialysis to continuous hemofiltration is associated with improved control of azotemia. The superior adequacy of small solute clearance achieved during CVVHDF provides additional support for its preferential use in the management of acute renal failure in the ICU.

Acute Kidney Injury↗
PubMed1999

Online monitoring in continuous renal replacement therapies.

Technical improvements in dialysis equipment for chronic hemodialysis patients has mirrored improvements in continuous renal replacement therapies (CRRTs) for patients with acute renal failure who are critically ill. This article reviews the available types and importance of online monitors such as urea sensors to provide real-time urea kinetic parameters, temperature sensors to target thermal balance throughout each session, conductivity measurement of sodium balance in the dialysate, blood volume monitoring to aid against cardiovascular instability and treatment-induced hypotension, biofeedback systems, and remote dialysis/teledialysis for efficient use of trained personnel.

Biosensing Techniques↗
PubMed1999

Use of adsorptive mechanisms in continuous renal replacement therapies in the critically ill.

The pathophysiology of sepsis is becoming a more complicated scenario. In sepsis, endotoxin or other gram-positive derived products induce a complex and dynamic cellular response giving rise to several mediators known to be relevant in the pathogenesis of septic shock, such as specific mediators. substances responsible for up- or down-regulation of cytokine receptors and cytokine antagonists, inactivators of nuclear factor-kappaB or signal transduction pathways, and precursor molecules. In this article, we delve into some new concepts stemming from the use of sorbents in continuous plasma filtration. The rationale is based on the assumption that the nonspecific removal of several mediators of the inflammatory cascade and cytokine network may improve outcome in a rabbit model of septic shock and hemodynamics in a pilot clinical study. The importance of looking for innovative treatments specifically targeted for the special needs of the critically ill patients rather than using concepts and technology applied to the treatment of chronic renal failure is underlined.

Animals↗
PubMed1999

Renal replacement therapy in the intensive care unit.

OBJECTIVE: To present an overview of the principles of renal replacement therapy, its application in the critically ill patient, and an update of recent research in this area. DATA SOURCES: Articles and published peer-review abstracts on the beneficial effects of continuous renal replacement therapy (CCRT) in the critically ill patient. SUMMARY OF REVIEW: Renal replacement therapy utilizes dialysers that enable solute and solvent to move across semipermeable membranes in either a convective or diffusive fashion. In the critically ill patient, percutaneous vascular access and improvement in dialysis machines, have facilitated the intensive care unit management of acute renal failure in these patients. Currently, CCRT is most often used to manage the critically ill patient with acute renal failure, as it is less likely to produce hypotension when compared with intermittent haemodialysis. However, CCRT has been expanded to manage critically ill patients with multiple organ failure, with the demonstration that it is able to remove or adsorb putative mediators of organ dysfunction. While there are experimental and uncontrolled clinical data that have suggested that this form of therapy is beneficial, currently there are no prospective randomised, controlled trials that have confirmed this benefit when used in these patients. CONCLUSIONS: Continuous renal replacement therapy has become commonplace in the management of critically ill patients with acute renal failure. It has the advantage of causing less hypotension and a more gradual return of the fluid and electrolyte status, when compared with intermittent haemodialysis. Recent evidence suggests that it may also be a useful immunomodulator and may be beneficial in the management of patients with multiple organ failure.

Journal Article↗
PubMed1999

The Effect of Preoperative Aspirin and/or Heparin Therapy on Coagulation and Postoperative Blood Loss after Coronary Artery Bypass Surgery.

OBJECTIVE: To assess the effects of preoperative aspirin and/or intravenous heparin therapy on perioperative coagulation tests and postoperative blood loss for 24-hour after coronary artery bypass surgery. METHODS: Multiple conventional coagulation tests, activated clotting time, thrombelastograph, skin bleeding time and platelet aggregation were performed before induction of anaesthesia, following protamine administration and after skin closure in 45 patients. RESULTS: There was no significant difference in either coagulation tests or postoperative blood loss (median of 860 mL with a range of 275 to 2800 mL, versus 833 ml with a range of 500-1380 mL) between the aspirin and no-aspirin patients. Preoperative heparin therapy affected most coagulation tests (e.g. international normalised ratio, activated partial thromboplastin time, thrombin clotting time, prothrombin time, activated clotting time and coagulation time of thrombelastography) before anaesthesia. The effects disappeared following protamine administration and after skin closure. Post operative blood loss was not significantly increased for the heparin group compared with the no-heparin group (median of 850 mL with a range of 700-1400 mL, versus 856 mL with a range of 275-2800 mL, respectively). Similar results were seen in patients receiving preoperative co-administration of aspirin and heparin compared with patients receiving aspirin alone. There was no suppression of platelet activity in patients receiving preoperative heparin or co-administration of aspirin and heparin. However, such suppression was found in patients receiving aspirin only. CONCLUSION: This study suggests that preoperative aspirin ingestion and intravenous heparin therapy should be administered as indicated and that concerns about the risk of postoperative bleeding should not lead to modification or cessation of such therapy.

Journal Article↗
PubMed1998

HLA class I-specific inhibitory receptors in human T lymphocytes: interleukin 15-induced expression of CD94/NKG2A in superantigen- or alloantigen-activated CD8+ T cells.

A fraction of human T lymphocytes, predominantly CD8+, express receptors for HLA class I molecules typical of natural killer cells (natural killer receptors or NKRs) that inhibit T cell receptor-mediated functions. Herein, we analyzed possible mechanism(s) leading to the expression of NKRs by T cells responding to superantigens or allogeneic cells in vitro. We show that, in the presence of interleukin 15 (IL-15), T cells (depleted of NKR+ cells) responding to toxic shock syndrome toxin 1 de novo express CD94, a molecule that is part of a heterodimeric NKR with a broad specificity for different HLA class I alleles. Maximal CD94 expression occurred when IL-15 was added shortly after the cells were placed into culture, and CD94 expression started 4-6 days after addition of IL-15. Although both CD4+ and CD8+ cells expressed CD94, the simultaneous expression of NKG2A (i.e., the other component of the CD94/NKG2A inhibitory NKR) was confined to CD8+ cells. Similar data were obtained in T cell populations activated in mixed lymphocyte cultures in the presence of IL-15. The expression of CD94/NKG2A led to an impairment of allo-specific cytolytic activity by mixed lymphocyte culture-derived T cell populations or clones. Remarkably, cytolysis could be restored by the addition of anti-CD94 mAb, i.e., by masking the inhibitory NKRs.

Antigens, CD↗
PubMed1998

Etiology of metabolic acidosis during saline resuscitation in endotoxemia.

We sought to understand the mechanism of metabolic acidosis that results in acute resuscitated endotoxic shock. In six pentobarbital-anesthetized dogs, shock was induced by Escherichia coli endotoxin infusion (1 mg/kg) and was treated with saline infusion to maintain mean arterial pressure > 80 mmHg. Blood gases and strong ions were measured during control conditions and at 15, 45, 90, and 180 min after endotoxin infusion. The mean saline requirement was 1833+/-523 mL over a 3 h period. The total acid load from each source was calculated using the standard base deficit. The mean arterial pH decreased from 7.32 to 7.11 (p < .01); pCO2 and lactate were unchanged. Saline accounted for 42% of the total acid load. However, 52% of the total acid load was unexplained. Although serum Na+ did not change, serum Cl-increased (127.7+/-5.1 mmol/L vs. 137.0+/-6.1 mmol/L; p=.016). We conclude that saline resuscitation alone accounts for more than one-third of the acidosis seen in this canine model of acute endotoxemia, whereas lactate accounts for less than 10%. A large amount of the acid load can be attributed to differential Na+ and Cl- shifts from extravascular to vascular spaces.

Acidosis↗
PubMed1998

The use of antimicrobials in ten Australian and New Zealand intensive care units. The Australian and New Zealand Intensive Care Multicentre Studies Group Investigators.

A prospective standardized collection of clinical, microbiological and pharmaceutical information on antibiotic use was conducted in Australia and New Zealand intensive care units (ICUs) involving 481 consecutive critically ill patients who were receiving antibiotics for any reason while in ICU. Patients had a mean SAPS II score of 34.1 +/- 17.8 with an expected mortality of 15.6% (actual mortality 12%). Of these, 292 (60.8%) were admitted to the ICU within 72 hours of surgery. Among such surgical patients, 233 (79.9%) received antibiotics for "surgical prophylaxis" while in ICU (48% of sample population). The second largest group of patients treated with antibiotics in ICU included those with systemic inflammatory response syndrome and clinical suspicion of infection (38%). Antibiotics were prescribed for the treatment of clinically diagnosed infection in 268 patients. Clinical response was apparent in 62.6% and in most (71%) was achieved in the first 72 hours of treatment. The incidence of antimicrobial-related side-effects was 4%, mostly in the form of diarrhoea or rash (75% of all side-effects). The most commonly prescribed antimicrobials were gentamicin (n = 146), ceftriaxone (n = 98), vancomycin (n = 94) and metronidazole (n = 111). Three times daily prescription of aminoglycosides was uncommon (< 1%). Forty-one patients had a documented infection (positive culture) with a gram-negative organism. Of these, 17 received therapy with a single antibiotic and 24 received therapy with two antibiotics. Despite similar illness severity, there were six deaths in the former group and only two in the latter.

Anti-Bacterial Agents↗
PubMed1998

Hemodynamic support and the role of dopamine.

The armamentarium of the critical care nephrologist contains several vasoactive and inotropic drugs with powerful effects on the systemic circulation. The physiologically logical use of these drug can be life-saving and have important beneficial effects on renal function. Such drug use must absolutely not be based on a "fixed dosage," but must instead be goal-directed with the aim of achieving those physiological states associated with hemodynamic stability and adequate vital organ perfusion. The achievement and maintenance of these goals must be prompt and guided by appropriate invasive hemodynamic monitoring and may require frequent changes in dosage. When these measures are adhered to, renal protection and clinical success are a much more likely outcome than when stereotyped approaches are followed.

Acute Kidney Injury↗
PubMed1998

Indications and criteria for initiating renal replacement therapy in the intensive care unit.

The decision to initiate renal replacement therapy is usually based on a careful assessment of conflicting priorities in the care of critically ill patients. It is particularly difficult because of the lack of information on what are the optimal criteria and indications for the application of renal replacement therapy (RRT) in the intensive care unit (ICU). As we will discuss in this paper, even though there are several time-honored indications for initiating dialytic therapy in patients with near end-stage renal failure, such indications may not apply to the management of acute renal failure (ARF). In fact, there are several reasons why a more aggressive approach and an earlier intervention may be justified in the ICU.

Acidosis↗