Effects of continuous venovenous haemofiltration-induced cooling on global haemodynamics, splanchnic oxygen and energy balance in critically ill patients

The Effect of Therapeutic Hypothermia on Prognosis in Patients Receiving Continuous Renal Replacement Therapy

Continuous renal replacement therapy (CRRT) is a commonly used therapeutic modality in the pediatric intensive care unit (PICU) for the treatment of severe acute kidney injury, as well as for addressing metabolic abnormalities, fluid-electrolyte imbalances, and acid-base disorders. According to reports, therapeutic hypothermia treatment has demonstrated the ability to decrease cellular metabolism, oxygen consumption, formation of free radicals, cell death, and inflammatory signals. The study encompassed all individuals who underwent CRRT at both Manisa City Hospital and Manisa Celal Bayar University Hospital throughout the period from February 2021 to November 2022. A total of 14 patients who received CRRT were subjected to a warming procedure utilizing an external blanket and an external heater attached to the CRRT venous return line, resulting in the attainment of a body temperature exceeding 36°C. Therapeutic hypothermia was implemented on 12 patients to maintain their body temperature within the range of 32-35°C. The study population exhibited a median age of 24.5 months, with males comprising 61.5% of the sample. A therapeutic hypothermia treatment was administered to a cohort of 12 patients. The patients who had therapeutic hypothermia exhibited a significantly reduced vasoactive-inotropic score (p = 0.038). Patients who did not receive therapeutic hypothermia exhibited a prolonged need for mechanical ventilation (p = 0.020). The duration of stay in the PICU for patients who underwent therapeutic hypothermia was shown to be considerably shorter compared to those who did not receive therapeutic hypothermia (p = 0.047). The potential efficacy of moderate therapeutic hypothermia appears promising, particularly in the context of patients who are receiving CRRT for severe sepsis and acute respiratory distress syndrome. This is attributed to the anti-inflammatory properties and hypometabolic effects associated with this intervention. To the best of our current understanding, this study represents the initial investigation showcasing the effectiveness of combining therapeutic hypothermia with CRRT in the pediatric population.

Metabolic and nutritional aspects in continuous renal replacement therapy

Nutrition is one of the foundations for supporting and treating critically ill patients. Nutritional support provides calories, protein, electrolytes, vitamins, and trace elements via the enteral or parenteral route. Acute kidney injury (AKI) is a common and devastating problem in critically ill patients and has significant metabolic and nutritional consequences. Moreover, renal replacement therapy (RRT), whatever the modality used, also profoundly impacts metabolism. RRT and of the extracorporeal circuit impede 'effect the evaluation of a patient's energy requirements by clinicians. Substrates added and removed within the extracorporeal treatment are not always taken into consideration, making treatment even more challenging. Furthermore, evidence on nutritional support during continuous renal replacement therapy (CRRT) is scarce, and there are no clinical guidelines for nutrition adaptations during CRRT in critically ill patients. Most recommendations are based on expert opinions. This review discusses the complex interaction between nutritional support and CRRT and presents some milestones for nutritional support in critically ill patients on CRRT.

An update review on hemodynamic instability in renal replacement therapy patients

BACKGROUND

Hemodynamic instability in patients undergoing kidney replacement therapy (KRT) is one of the most common and essential factors influencing mortality, morbidity, and the quality of life in this patient population.

METHOD

Decreased cardiac preload, reduced systemic vascular resistance, redistribution of fluids, fluid overload, inflammatory factors, and changes in plasma osmolality have all been implicated in the pathophysiology of hemodynamic instability associated with KRT.

RESULT

A cascade of these detrimental mechanisms may ultimately cause intra-dialytic hypotension, reduced tissue perfusion, and impaired kidney rehabilitation. Multiple parameters, including dialysate composition, temperature, posture during dialysis sessions, physical activity, fluid administrations, dialysis timing, and specific pharmacologic agents, have been studied as possible management modalities. Nevertheless, a clear consensus is not reached.

CONCLUSION

This review includes a thorough investigation of the literature on hemodynamic instability in KRT patients, providing insight on interventions that may potentially minimize factors leading to hemodynamic instability.

Targeted high volume hemofiltration could avoid extracorporeal membrane oxygenation in some patients with severe Hantavirus cardiopulmonary syndrome

Background

Hantavirus cardiopulmonary syndrome (HCPS) has a high lethality. Severe cases may be rescued by venoarterial extracorporeal membrane oxygenation (VA ECMO), alongside substantial complications. High volume hemofiltration (HVHF) is a depurative technique that provides homeostatic balance allowing hemodynamic stabilization in some critically ill patients.

Methods

We implemented HVHF before VA ECMO consideration in the last five severe HCPS patients requiring mechanical ventilation and vasoactive drugs admitted to our intensive care unit. Patients were considered HVHF‐responders if VA ECMO was avoided and HVHF‐nonresponders if VA ECMO support was needed despite HVHF. A targeted‐HVHF strategy compounded by aggressive hyperoncotic albumin, sodium bicarbonate, and calcium supplementation plus ultrafiltration to avoid fluid overload was implemented on three patients.

Results

Patients had maximum serum lactate of 8.8 (8.7–12.8) mmol/L and a lowest cardiac index of 1.8 (1.8–1.9) L/min/m². The first two required VA ECMO. They were connected later to HVHF, displayed progressive tachycardia and declining stroke volume. The opposite was true for HVHF‐responders who received targeted‐HVHF. All patients survived, but one of the VA ECMO patients suffered a vascular complication.

Conclusion

HVHF may contribute to support severe HCPS patients avoiding the need for VA ECMO in some. Early connection and targeted‐HVHF may increase the chance of success.

A Pilot Study Evaluating the Effect of Cooler Dialysate Temperature on Hemodynamic Stability During Prolonged Intermittent Renal Replacement Therapy in Acute Kidney Injury

OBJECTIVES

Acute kidney injury requiring renal replacement therapy is associated with high morbidity and mortality. Complications of renal replacement therapy include hemodynamic instability with ensuing shortened treatments, inadequate ultrafiltration, and delay in renal recovery. Studies have shown that lowering dialysate temperature in patients with end-stage renal disease is associated with a decrease in the frequency of intradialytic hypotension. However, data regarding mitigation of hypotension by lowering dialysate temperature in patients with acute kidney injury are scarce. We conducted a prospective, randomized, cross-over pilot study to evaluate the effect of lower dialysate temperature on hemodynamic status of critically ill patients with acute kidney injury during prolonged intermittent renal replacement therapy.

DESIGN

Single-center prospective, randomized, cross-over study.

SETTING

ICUs and a step down unit in a tertiary referral center.

PATIENTS

Acute kidney injury patients undergoing prolonged intermittent renal replacement therapy.

INTERVENTIONS

Participants were randomized to start prolonged intermittent renal replacement therapy with dialysate temperature of 35°C or dialysate temperature of 37°C.

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was the number of hypotensive events, as defined by any of the following: decrease in systolic blood pressure greater than or equal to 20 mm Hg, decrease in mean arterial pressure greater than or equal to 10 mm Hg, decrease in ultrafiltration, or increase in vasopressor requirements. The number of events was analyzed by Poisson regression and other outcomes with repeated-measures analysis of variance. Twenty-one patients underwent a total of 78 prolonged intermittent renal replacement therapy sessions, 39 in each arm. The number of hypotensive events was twice as high during treatments with dialysate temperature of 37°C, compared with treatments with the cooler dialysate (1.49 ± 1.12 vs 0.72 ± 0.69; incidence rate ratio, 2.06; p ≤ 0.0001). Treatment sessions with cooler dialysate were more likely to reach prescribed ultrafiltration targets.

CONCLUSIONS

Patients with acute kidney injury undergoing prolonged intermittent renal replacement therapy with cooler dialysate experienced significantly less hypotension during treatment. Prevention of hemodynamic instability during renal replacement therapy helped to achieve ultrafiltration goals and may help to prevent volume overload in critically ill patients.

Mechanisms for hemodynamic instability related to renal replacement therapy: a narrative review

Hemodynamic instability related to renal replacement therapy (HIRRT) is a frequent complication of all renal replacement therapy (RRT) modalities commonly used in the intensive care unit. HIRRT is associated with increased mortality and may impair kidney recovery. Our current understanding of the physiologic basis for HIRRT comes primarily from studies of end-stage kidney disease patients on maintenance hemodialysis in whom HIRRT is referred to as ‘intradialytic hypotension’. Nonetheless, there are many studies that provide additional insights into the underlying mechanisms for HIRRT specifically in critically ill patients. In particular, recent evidence challenges the notion that HIRRT is almost entirely related to excessive ultrafiltration. Although excessive ultrafiltration is a key mechanism, multiple other RRT-related mechanisms may precipitate HIRRT and this could have implications for how HIRRT should be managed (e.g., the appropriate response might not always be to reduce ultrafiltration, particularly in the context of significant fluid overload). This review briefly summarizes the incidence and adverse effects of HIRRT and reviews what is currently known regarding the mechanisms underpinning it. This includes consideration of the evidence that exists for various RRT-related interventions to prevent or limit HIRRT. An enhanced understanding of the mechanisms that underlie HIRRT, beyond just excessive ultrafiltration, may lead to more effective RRT-related interventions to mitigate its occurrence and consequences.

Noninvasive quantification of oxygen saturation in the portal and hepatic veins in healthy mice and those with colorectal liver metastases using QSM MRI

PURPOSE

This preclinical study investigated the use of QSM MRI to noninvasively measure venous oxygen saturation (SvO2) in the hepatic and portal veins.

METHODS

QSM data were acquired from a cohort of healthy mice (n = 10) on a 9.4 Tesla MRI scanner under normoxic and hyperoxic conditions. Susceptibility was measured in the portal and hepatic veins and used to calculate SvO2 in each vessel under each condition. Blood was extracted from the inferior vena cava of 3 of the mice under each condition, and SvO2 was measured with a blood gas analyzer for comparison. QSM data were also acquired from a cohort of mice bearing liver tumors under normoxic conditions. Susceptibility was measured, and SvO2 calculated in the portal and hepatic veins and compared to the healthy mice. Statistical significance was assessed using a Wilcoxon matched-pairs signed rank test (normoxic vs. hyperoxic) or a Mann-Whitney test (healthy vs. tumor bearing).

RESULTS

SvO2 calculated from QSM measurements in healthy mice under hyperoxia showed significant increases of 15% in the portal vein (P < 0.05) and 21% in the hepatic vein (P < 0.01) versus normoxia. These values agreed with inferior vena cava measurements from the blood gas analyzer (26% increase). SvO2 in the hepatic vein was significantly lower in the colorectal liver metastases cohort (30% ± 11%) than the healthy mice (53% ± 17%) (P < 0.05); differences in the portal vein were not significant.

CONCLUSION

QSM is a feasible tool for noninvasively measuring SvO2 in the liver and can detect differences due to increased oxygen consumption in livers bearing colorectal metastases.

Energy expenditure and caloric targets during continuous renal replacement therapy under regional citrate anticoagulation. A viewpoint

BACKGROUND

Indirect calorimetry (IC) is the gold standard for measuring energy expenditure in critically ill patients However, continuous renal replacement therapy (CRRT) is a formal contraindication for IC use.

AIMS

To discuss specific issues that hamper or preclude an IC-based assessment of energy expenditure and correct caloric prescription in CRRT-treated patients.

METHODS

Narrative review of current literature.

RESULTS

Several relevant pitfalls for validation of IC during CRRT were identified. First, IC measures CO₂ production (VCO₂) and O₂ consumption to calculate resting energy expenditure (REE) with the Weir equation. VCO₂ measurements are influenced by CRRT because CO₂ is exchanged during the blood purification process. CO₂ exchange also depends on type of pre- and/or postdilution fluid(s). CO₂ dissolves in different forms with dynamic but unpredictable impact on VCO₂. Second, the effect of immunologic activation and heat loss on REE caused by extracorporeal circulation during CRRT is poorly documented. Third, caloric prescription should be adapted to CRRT-induced in- and efflux of different nutrients. Finally, citrate, which is the preferred anticoagulant for CRRT, is a caloric source that may influence IC measurements and REE.

CONCLUSION

Better understanding of CRRT-related processes is needed to assess REE and provide individualized nutritional therapy in this condition.

Modification of Nutrition Therapy During Continuous Renal Replacement Therapy in Critically Ill Pediatric Patients: A Narrative Review and Recommendations

Introduction

Nutrition is an important part of treatment in critically ill children. Clinical guidelines for nutrition adaptations during continuous renal replacement therapy (CRRT) are lacking. We collected and evaluated current knowledge on this topic and provide recommendations.

Methods

Questions were produced to guide the literature search in the PubMed database.

Results

Evidence is scarce and extrapolation from adult data was often required. CRRT has a direct and substantial impact on metabolism. Indirect calorimetry is the preferred method to assess resting energy expenditure (REE). Moderate underestimation of REE is common but not clinically relevant. Formula‐based calculation of REE is inaccurate and not validated in critically ill children on CRRT. The nutrition impact of nonintentional calories delivered as citrate, lactate, and glucose during CRRT must be considered. Quantifying nitrogen balance is not feasible during CRRT. Protein delivery should be increased by 25% to compensate for losses in the effluent. Fats are not removed by CRRT and should not be adapted during CRRT. Electrolyte disturbances are frequently present and should be treated accordingly. Vitamins B1, B6, B9, and C are lost in the effluent and should be adapted to the effluent dose. Trace elements, with the exception of selenium, are not cleared in relevant quantities. Manganese accumulation is of concern because of potential neurotoxicity.

Conclusion

Current recommendations regarding nutrition support in pediatric CRRT must be extrapolated from adult studies. Recommendations are provided, based on the weak level of evidence. Additional research on this topic is warranted.

Extracorporeal techniques for the treatment of critically ill patients with sepsis beyond conventional blood purification therapy: the promises and the pitfalls

Sepsis is one of the leading causes of morbidity and mortality worldwide. It is characterized by a dysregulated immune response to infections that results in life-threatening organ dysfunction and even death. Bacterial cell wall components (endotoxin or lipopolysaccharide), known as pathogen-associated molecular patterns (PAMPs), as well as damage-associated molecular patterns (DAMPs) released by host injured cells, are well-recognized triggers resulting in the elevation of both pro-inflammatory and anti-inflammatory cytokines. Understanding this complex pathophysiology has led to the development of therapeutic strategies aimed at restoring a balanced immune response by eliminating/deactivating these inflammatory mediators. Different extracorporeal techniques have been studied in recent years in the hope of maximizing the effect of renal replacement therapy in modulating the exaggerated host inflammatory response, including the use of high volume hemofiltration (HVHF), high cut-off (HCO) membranes, adsorption alone, and coupled plasma filtration adsorption (CPFA). These strategies are not widely utilized in practice, depending on resources and local expertise. The literature examining their use in septic patients is growing, but the evidence to support their use at this stage is considered of low level. Our aim is to provide a comprehensive overview of the technical aspects, clinical applications, and associated side effects of these techniques.

Interventions to prevent hemodynamic instability during renal replacement therapy in critically ill patients: a systematic review

Background

Hemodynamic instability related to renal replacement therapy (HIRRT) may increase the risk of death and limit renal recovery. Studies in end-stage renal disease populations on maintenance hemodialysis suggest that some renal replacement therapy (RRT)-related interventions (e.g., cool dialysate) may reduce the occurrence of HIRRT, but less is known about interventions to prevent HIRRT in critically ill patients receiving RRT for acute kidney injury (AKI). We sought to evaluate the effectiveness of RRT-related interventions for reducing HIRRT in such patients across RRT modalities.

Methods

A systematic review of publications was undertaken using MEDLINE, MEDLINE in Process, EMBASE, and Cochrane’s Central Registry for Randomized Controlled Trials (RCTs). Studies that assessed any intervention’s effect on HIRRT (the primary outcome) in critically ill patients with AKI were included. HIRRT was variably defined according to each study’s definition. Two reviewers independently screened abstracts, identified articles for inclusion, extracted data, and evaluated study quality using validated assessment tools.

Results

Five RCTs and four observational studies were included (n = 9; 623 patients in total). Studies were small, and the quality was mostly low. Interventions included dialysate sodium modeling (n = 3), ultrafiltration profiling (n = 2), blood volume (n = 2) and temperature control (n = 3), duration of RRT (n = 1), and slow blood flow rate at initiation (n = 1). Some studies applied more than one strategy simultaneously (n = 5). Interventions shown to reduce HIRRT from three studies (two RCTs and one observational study) included higher dialysate sodium concentration, lower dialysate temperature, variable ultrafiltration rates, or a combination of strategies. Interventions not found to have an effect included blood volume and temperature control, extended duration of intermittent RRT, and slower blood flow rates during continuous RRT initiation. How HIRRT was defined and its frequency of occurrence varied widely across studies, including those involving the same RRT modality. Pooled analysis was not possible due to study heterogeneity.

Conclusions

Small clinical studies suggest that higher dialysate sodium, lower temperature, individualized ultrafiltration rates, or a combination of these strategies may reduce the risk of HIRRT. Overall, for all RRT modalities, there is a paucity of high-quality data regarding interventions to reduce the occurrence of HIRRT in critically ill patients.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-1965-5) contains supplementary material, which is available to authorized users.

Continuous Renal Replacement Therapy Update: An Emphasis on Safe and High-Quality Care

Continuous renal replacement therapy (CRRT) was introduced more than 40 years ago as a renal support option for critically ill patients who had contraindications to intermittent hemodialysis and peritoneal dialysis. Despite being the most common renal support therapy used in intensive care units today, the tremendous variability in CRRT management challenges the interpretation of findings from CRRT outcome studies. The lack of standardization in practice and training of clinicians along with the high risk of CRRT-related adverse events has been the impetus for the recent expert consensus work on identifying quality indicators for CRRT programs. This article summarizes the potential complications that establish CRRT as a high-risk therapy and also the recently published best-practice recommendations for providing high-quality CRRT.

Intradialytic hypotension in acute kidney injury requiring renal replacement therapy

The treatment of severe acute kidney injury (AKI) with dialytic support for renal replacement therapy can be life sustaining and permit recovery from critical illness. Like any interventional therapy, however, renal replacement therapy with intermittent hemodialysis or continuous therapy can cause complications. Intradialytic hypotension is a common complication and can cause further ischemic injury to the recovering kidneys, thereby reducing the probability of renal recovery. The optimal dialytic technique-continuous or intermittent-has not been conclusively demonstrated in randomized controlled trials. In general, treatment or prophylactic strategies for intradialytic hypotension in AKI have not been comprehensively tested. Given the frequency of intradialytic hypotension in dialytic treatment of AKI and its adverse clinical consequences, future research should rigorously compare dialytic techniques and other prevention strategies in adequately powered, randomized controlled trials.

Metabolic and Nutritional Aspects of Acute Renal Failure in Critically Ill Patients Requiring Continuous Renal Replacement Therapy

Acute renal failure (ARF) is rarely an isolated process but is often a complication of underlying conditions such as sepsis, trauma, and multiple-organ failure in critically ill patients. As such, concomitant clinical conditions significantly affect patient outcome. Poor nutritional status is a major factor in increasing patients' morbidity and mortality. Malnutrition in ARF patients is caused by hypercatabolism and hypermetabolism that parallel the severity of illness. When dialytic intervention is indicated, continuous renal replacement therapy (CRRT) is a commonly used alternative to intermittent hemodialysis because it is well tolerated by hemodynamically unstable patients. This paper reviews the metabolic and nutritional alterations associated with ARF and provides recommendations regarding the nutritional, fluid, electrolyte, micronutrient, and acid-base management of these patients. The basic principles of CRRT are addressed, along with their nutritional implications in critically ill patients. A patient case is presented to illustrate the clinical application of topics covered within the paper.

Should we treat pyrexia? And how do we do it?

The concept of pyrexia as a protective physiological response to aid in host defence has been challenged with the awareness of the severe metabolic stress induced by pyrexia. The host response to pyrexia varies, however, according to the disease profile and severity and, as such, the management of pyrexia should differ; for example, temperature control is safe and effective in septic shock but remains controversial in sepsis. From the reported findings discussed in this review, treating pyrexia appears to be beneficial in septic shock, out of hospital cardiac arrest and acute brain injury.Multiple therapeutic options are available for managing pyrexia, with precise targeted temperature management now possible. Notably, the use of pharmacotherapy versus surface cooling has not been shown to be advantageous. The importance of avoiding hypothermia in any treatment strategy is not to be understated.Whilst a great deal of progress has been made regarding optimal temperature management in recent years, further studies will be needed to determine which patients would benefit the most from control of pyrexia and by which means this should be implemented. This narrative review is part of a series on the pathophysiology and management of pyrexia.

Influence of different dialysis modalities in the measurement of resting energy expenditure in patients with acute kidney injury in ICU

BACKGROUND

Currently, the execution of indirect calorimetry, which is considered the gold standard for measuring energy expenditure, is not indicate during dialysis, and it may interfere on nutritional therapy of these patients. This study aimed to evaluate the resting energy expenditure (REE) in patients with severe acute kidney injury treated by different modalities of dialysis and to identify whether dialysis influences on REE.

METHODS

This was a prospective cohort study that evaluated patients admitted in intensive care units with diagnosis of acute kidney injury AKIN-3, mechanically ventilated, and submitted to conventional hemodialysis (CHD), extended hemodialysis (EHD) or high volume peritoneal dialysis (HVPD). Indirect calorimetry was performed at pre dialysis time and during the dialysis procedure. Parameters that could change REE were also evaluated.

RESULTS

One-hundred patients undergoing 290 dialysis sessions were evaluated, with mean age 60.3 ± 17 years, 69% were male and 74% have died. There was no significant difference between REE of predialysis time and during dialysis time (2156 ± 659 kcal vs. 2100 ± 634 kcal, respectively, p = 0.15). No difference was observed in the REE before and during dialysis of different modalities. There were no differences between parameters pre and during dialysis of each modality. There was only a difference in norepinephrine dose, which was higher in pre dialysis time in HVPD and EHD modalities, compared with CHD modality. Moreover, during dialysis time, EHD modality had significantly higher VAD compared to other dialysis modalities.

CONCLUSION

The three evaluated modalities did not change REE. Indirect calorimetry can be performed during dialysis procedures and there was no difference between ventilation parameters, sedatives use, body temperature and VAD in both moments.

[Is control fever mandatory in severe infections?]

Temperature control during severe sepsis is currently used in intensive care and involves 66% and 70% of severe sepsis and septic shock, respectively. Nevertheless, the conclusive evidence of the benefit of such a strategy is still lacking.We might wonder, with regards to experimental works and recent noninterventional studies, about the risk of a control strategy on an ongoing infectious process, the patient's outcome, and the safety of the means implemented to obtain temperature control. On the other hand, it is also demonstrated that fever increases oxygen consumption, which may lead in some clinical situations to tissular ischemia and that fever may be associated with a deleterious focal inflammatory process. Methods to control the temperature include external and/or internal cooling and/or antipyretic medications such as paracetamol and nonsteroidal antiinflammatory drugs. In septic patients, external cooling and paracetamol are the mains means used to control temperature. Despite the uncertainties about the benefit to control or not the temperature, it could be stated that extreme temperature (hypo- or hyperthermia) should be avoided and that the benefit/risk of temperature control must be individually weighted.

Prevention of intradialytic hypotension in patients with acute kidney injury submitted to sustained low-efficiency dialysis

OBJECTIVES

This study evaluated the effects of a protocol aiming to reduce hypotension in acute kidney injury (AKI) patients submitted to sustained low-efficiency dialysis (SLED).

METHODS

Patients were randomly assigned to two SLED prescriptions-control group, dialysate temperature was 37.0°C with a fixed sodium concentration [138 mEq/L] and ultrafiltration (UF) rate; and profiling group, dialysate temperature was 35.5°C with a variable sodium concentration [150-138 mEq/L] and UF rate.

RESULTS

Sixty-two SLED sessions were evaluated (34 in profiling and 28 in control). Patients (n = 31) were similar in terms of gender, age, and Sequential Organ Failure Assessment (SOFA) score. Dialysis time, dialysis dose, and post-dialysis serum sodium were similar in both groups. The profiling group had significantly less hypotension episodes (23% vs. 57% in control, p = 0.009) and achieved higher UF volume (2.23 ± 1.25 L vs. 1.59 ± 1.03 L in control, p = 0.04) when compared with control group.

CONCLUSIONS

SLED protocol with modulation of dialysate temperature, sodium, and UF profiling showed similar efficacy but less intradialytic hypotension when compared with a standard SLED prescription.

Benefits of an early cooling phase in continuous renal replacement therapy for ICU patients

Background

Lowering the temperature setting in the heating device during continuous venovenous hemofiltration (CVVH) is an option. The purpose of this study was to determine the effects on body temperature and hemodynamic tolerance of two different temperature settings in the warming device in patients treated with CVVH.

Methods

Thirty patients (mean age: 66.5 years; mean SAPS 2: 55) were enrolled in a prospective crossover randomized study. After a baseline of 2 h at 38°C, the heating device was randomly set to 38°C (group A) and 36°C (group B) for 6 h. Then, the temperatures were switched to 36°C in group A and to 38°C in group B for another 6 h. Hemodynamic parameters and therapeutic interventions to control the hemodynamics were recorded.

Results

There was no significant change in body temperature in either group. During the first 6 h, group B patients showed significantly increased arterial pressure (p = 0.01) while the dosage of catecholamine was significantly decreased (p = 0.04). The number of patients who required fluid infusion or increase in catecholamine dosage was similar. During the second period of the study, hemodynamic parameters were unchanged in both groups.

Conclusions

In patients undergoing CVVH, warming of the substitute over 36°C had no impact on body temperature. We showed that setting the fluid temperature at 36°C for a period of time early in the procedure is beneficial in terms of increased mean arterial pressure and decreased catecholamine infusion dosage.

Impaired bioavailability and antiplatelet effect of high-dose clopidogrel in patients after cardiopulmonary resuscitation (CPR)

PURPOSE

Bioavailability of clopidogrel in the form of crushed tablets administered via nasogastric tube (NGT) has not been established in patients after cardiopulmonary resuscitation. Therefore, we performed a study comparing pharmacokinetic and pharmacodynamic response to high loading dose of clopidogrel in critically ill patients after cardiopulmonary resuscitation (CPR) with patients scheduled for elective coronary angiography with stent implantation.

METHODS

In the NGT group (nine patients, after cardiopulmonary resuscitation, mechanically ventilated, therapeutic hypothermia), clopidogrel was administered in the form of crushed tablets via NGT. Ten patients undergoing elective coronary artery stenting took clopidogrel per os (po) in the form of intact tablets. Pharmacokinetics of clopidogrel was measured with high-performance liquid chromatography (HPLC) before and at 0.5, 1, 6, 12, 24 h after administration of a loading dose of 600 mg. In five patients in each group, antiplatelet effect was measured with thrombelastography (TEG; Platelet Mapping) before and 24 h after administration.

RESULTS

The carboxylic acid metabolite of clopidogrel was detected in all patients in the po group. In eight patients, the maximum concentration was measured in the range of 0.5-1 h after the initial dose. In four patients in the of NGT group, the carboxylic acid metabolite of clopidogrel was undetectable and in the remaining patients was significantly delayed (peak values at 12 h). All patients in the po group reached clinically relevant (>50 %) inhibition of thrombocyte adenosine diphosphate (ADP) receptor after 24 h compared with only two in the NGT group (p = 0.012). There was a close correlation between peak of inactive clopidogrel metabolite plasmatic concentration and inhibition of the ADP receptor (r = 0.79; p < 0.001).

CONCLUSION

The bioavailability of clopidogrel in critically ill patients after cardiopulmonary resuscitation is significantly impaired compared with stable patients. Therefore, other drugs, preferentially administered intravenously, should be considered.

In a porcine model of mixed acidemia HES 130/0.4 may support more stable hemodynamics during CVVH when compared to gelatine

PURPOSE

Continuous veno-venous hemofiltration (CVVH) and mixed acidemia often occur simultaneously in critically ill patients. In a previous study in non-acidemic pigs we found that colloids and CVVH interact specifically with respect to hemodynamic stability, with favorable effects for 6% HES 130/0.4 versus 4% gelatine (GEL) infusion. In a porcine model, we investigated whether these colloid-type associated differences are still dominant under acidemic conditions.

METHODS

We utilized 5 groups, a non-acidemic reference group receiving HES130 and CVVH; two acidemic groups receiving HES130 infusion (one with and one without CVVH); and two acidemic groups receiving GEL infusion (one with and one without CVVH). Mixed acidemia (pH ~7.20) was established by low tidal volume ventilation and acid infusion. Stable acidemia/CVVH application was maintained for 3 hours. Hemodynamics and blood gases were recorded.

RESULTS

Mixed acidemia led to a significant decrease in MAP and increase in MPAP in all groups. CVVH led to a further decrease in MAP but improved MPAP. During CVVH, HES130 ensured significantly higher MAP, Hb, and DO2 values than GEL infusion. In the groups without CVVH these differences between HES 130/0.4 and GEL were not observed.

CONCLUSIONS

As in a previous study in non-acidemic pigs, we found a colloid-specific influence of HES130 versus GEL on hemodynamics during CVVH under acidemia. Again, HES130 infusion may lead to favorable effects. In contrast, acidemia without CVVH application was dominant over the impact of a respective colloid. The application of a CVVH seems to be an important trigger for the overall circulatory response to a particular colloid.

Fever control using external cooling in septic shock: a randomized controlled trial

RATIONALE

Fever control may improve vascular tone and decrease oxygen consumption, but fever may contribute to combat infection.

OBJECTIVES

To determine whether fever control by external cooling diminishes vasopressor requirements in septic shock.

METHODS

In a multicenter randomized controlled trial, febrile patients with septic shock requiring vasopressors, mechanical ventilation, and sedation were allocated to external cooling (n = 101) to achieve normothermia (36.5-37°C) for 48 hours or no external cooling (n = 99). Vasopressors were tapered to maintain the same blood pressure target in the two groups. The primary endpoint was the number of patients with a 50% decrease in baseline vasopressor dose after 48 hours.

MEASUREMENTS AND MAIN RESULTS

Body temperature was significantly lower in the cooling group after 2 hours of treatment (36.8 ± 0.7 vs. 38.4 ± 1.1°C; P < 0.01). A 50% vasopressor dose decrease was significantly more common with external cooling from 12 hours of treatment (54 vs. 20%; absolute difference, 34%; 95% confidence interval [95% CI], -46 to -21; P < 0.001) but not at 48 hours (72 vs. 61%; absolute difference, 11%; 95% CI, -23 to 2). Shock reversal during the intensive care unit stay was significantly more common with cooling (86 vs. 73%; absolute difference, 13%; 95% CI, 2 to 25; P = 0.021). Day-14 mortality was significantly lower in the cooling group (19 vs. 34%; absolute difference, -16%; 95% CI, -28 to -4; P = 0.013).

CONCLUSIONS

In this study, fever control using external cooling was safe and decreased vasopressor requirements and early mortality in septic shock.

Effect of the intensity of continuous renal replacement therapy in patients with sepsis and acute kidney injury: a single-center randomized clinical trial

INTRODUCTION

Acute kidney injury (AKI) is a major complication in patients with sepsis and is an independent predictor of mortality. However, the optimal intensity of renal replacement therapy for such patients is still controversial.

METHODS

From 1 January 2004 to 30 September 2009, we randomly assigned 280 patients with sepsis and AKI to continuous renal replacement therapy by high-volume hemofiltration (50 mL/kg/h, HVHF) or extra high-volume hemofiltration (85 mL/kg/h, EHVHF). The primary study outcome was death from any cause within 28, 60 and 90 days. Results were analyzed by univariate and multivariate methods and by Kaplan-Meier survival curves.

RESULTS

A total of 141 patients were given EHVHF and 139 were given HVHF. The two groups had similar baseline characteristics and received treatment for an average of 9.38 days (EHVHF group) and 8.88 days (HVHF group). There were no significant differences between the groups in number of deaths at 28, 60 or 90 days. There were also no differences between the groups in renal outcome of survivors at 90 days. Multivariate analysis indicated that inotropic support by norepinephrine, time in hospital of >7 days, blood platelet count <8 × 10(9)/L, Acute Physiological and Chronic Health Evaluation (APACHE) II score >25, total bilirubin >100 μmol/L, prothrombin time >18 s, serum creatinine <250 μmol/L and blood urea nitrogen >20 mmol/L were independent risk factors for death at 90 days after initiation of renal replacement therapy.

CONCLUSIONS

In patients with sepsis and AKI, increasing the intensity of renal replacement therapy from 50 (HVHF) to 85 mL/kg/h (EHVHF) had no effect on survival at 28 and 90 days.

An Official ATS/ERS/ESICM/SCCM/SRLF Statement: Prevention and Management of Acute Renal Failure in the ICU Patient: an international consensus conference in intensive care medicine

OBJECTIVES

To address the issues of Prevention and Management of Acute Renal Failure in the ICU Patient, using the format of an International Consensus Conference.

METHODS AND QUESTIONS

Five main questions formulated by scientific advisors were addressed by experts during a 2-day symposium and a Jury summarized the available evidence: (1) Identification and definition of acute kidney insufficiency (AKI), this terminology being selected by the Jury; (2) Prevention of AKI during routine ICU Care; (3) Prevention in specific diseases, including liver failure, lung Injury, cardiac surgery, tumor lysis syndrome, rhabdomyolysis and elevated intraabdominal pressure; (4) Management of AKI, including nutrition, anticoagulation, and dialysate composition; (5) Impact of renal replacement therapy on mortality and recovery.

RESULTS AND CONCLUSIONS

The Jury recommended the use of newly described definitions. AKI significantly contributes to the morbidity and mortality of critically ill patients, and adequate volume repletion is of major importance for its prevention, though correction of fluid deficit will not always prevent renal failure. Fluid resuscitation with crystalloids is effective and safe, and hyperoncotic solutions are not recommended because of their renal risk. Renal replacement therapy is a life-sustaining intervention that can provide a bridge to renal recovery; no method has proven to be superior, but careful management is essential for improving outcome.

Effects of Initiation of Continuous Renal Replacement Therapy on Hemodynamics in a Pediatric Animal Model

There are no studies analyzing the initial hemodynamic impact of continuous renal replacement therapy (CRRT) in children. We have performed a prospective observational study in 34 immature Maryland pigs to analyze the initial hemodynamic changes during venovenous CRRT. The heart rate, blood pressure, central venous pressure (CVP), pulmonary arterial occlusion pressure (PAOP), pulmonary capillary wedge pressure, temperature, and cardiac output (CO), simultaneously by pulmonary arterial thermodilution and femoral arterial thermodilution, were measured at 30-min intervals during 2 h. Venovenous CRRT induced an initial significant diminution of volemic hemodynamic parameters (intrathoracic blood volume, global end-diastolic volume, stroke volume index, PAOP, and CVP). Simultaneously, a significant increase in systemic vascular resistance index and left ventricular contractility, and a decrease in CO, was observed. We conclude that CRRT in a pediatric animal model induces initial hypovolemia, and a systemic cardiovascular response with vasoconstriction and increase in ventricular contractility.

High versus standard-volume haemofiltration in hyperdynamic porcine peritonitis: effects beyond haemodynamics?

OBJECTIVE

The role of haemofiltration as an adjunctive treatment of sepsis remains a contentious issue. To address the role of dose and to explore the biological effects of haemofiltration we compared the effects of standard and high-volume haemofiltration (HVHF) in a peritonitis-induced model of porcine septic shock.

DESIGN AND SETTING

Randomized, controlled experimental study.

SUBJECTS

Twenty-one anesthetized and mechanically ventilated pigs.

INTERVENTIONS

After 12 h of hyperdynamic peritonitis, animals were randomized to receive either supportive treatment (Control, n = 7) or standard haemofiltration (HF 35 ml/kg per h, n = 7) or HVHF (100 ml/kg per hour, n = 7).

MEASUREMENTS AND RESULTS

Systemic and hepatosplanchnic haemodynamics, oxygen exchange, energy metabolism (lactate/pyruvate, ketone body ratios), ileal and renal cortex microcirculation and systemic inflammation (TNF-alpha, IL-6), nitrosative/oxidative stress (TBARS, nitrates, GSH/GSSG) and endothelial/coagulation dysfunction (von Willebrand factor, asymmetric dimethylarginine, platelet count) were assessed before, 12, 18, and 22 h of peritonitis. Although fewer haemofiltration-treated animals required noradrenaline support (86, 43 and 29% animals in the control, HF and HVHF groups, respectively), neither of haemofiltration doses reversed hyperdynamic circulation, lung dysfunction and ameliorated alterations in gut and kidney microvascular perfusion. Both HF and HVHF failed to attenuate sepsis-induced alterations in surrogate markers of cellular energetics, nitrosative/oxidative stress, endothelial injury or systemic inflammation.

CONCLUSIONS

In this porcine model of septic shock early HVHF proved superior in preventing the development of septic hypotension. However, neither of haemofiltration doses was capable of reversing the progressive disturbances in microvascular, metabolic, endothelial and lung function, at least within the timeframe of the study and severity of the model.

Control of core temperature and blood pressure stability during hemodialysis

BACKGROUND AND OBJECTIVES

Cool dialysate may ameliorate intradialytic hypotension (IDH). It is not known whether it is sufficient to prevent an increase in core temperature (CT) during hemodialysis (HD) or whether a mild decline in CT would yield superior results. The aim of this study was to compare both approaches with regard to IDH.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Fourteen HD patients with a history of IDH were studied. During three mid-week HD treatments, CT was set to decrease by 0.5 degrees C ("cooling") or to remain unchanged at the baseline level ("isothermic"). "Thermoneutral" HD (no energy is added to or removed from the patient) was used as a control. Central blood volume (CBV), BP, skin temperature, heart rate variability [low and high frequency] were recorded.

RESULTS

CT increased during thermoneutral and remained respectively stable and decreased during isothermic and cooling. Skin temperature decreased significantly during isothermic and cooling, but not during thermoneutral. Nadir systolic BP (SBP) levels were lower during isothermic and thermoneutral compared with cooling. CBV tended to be higher during cooling compared with isothermic and thermoneutral. Three patients complained of shivering during cooling. Change in LF/HF was not different between cooling, isothermic, and thermoneutral.

CONCLUSIONS

IDH may be slightly improved by cooling compared with the isothermic approach, possibly because of improved maintenance of CBV. The hemodynamic effects of mild blood cooling should be balanced against a potentially higher risk of cold discomfort.

Bench-to-bedside review: metabolism and nutrition

Acute kidney injury (AKI) develops mostly in the context of critical illness and multiple organ failure, characterized by alterations in substrate use, insulin resistance, and hypercatabolism. Optimal nutritional support of intensive care unit patients remains a matter of debate, mainly because of a lack of adequately designed clinical trials. Most guidelines are based on expert opinion rather than on solid evidence and are not fundamentally different for critically ill patients with or without AKI. In patients with a functional gastrointestinal tract, enteral nutrition is preferred over parenteral nutrition. The optimal timing of parenteral nutrition in those patients who cannot be fed enterally remains controversial. All nutritional regimens should include tight glycemic control. The recommended energy intake is 20 to 30 kcal/kg per day with a protein intake of 1.2 to 1.5 g/kg per day. Higher protein intakes have been suggested in patients with AKI on continuous renal replacement therapy (CRRT). However, the inadequate design of the trials does not allow firm conclusions. Nutritional support during CRRT should take into account the extracorporeal losses of glucose, amino acids, and micronutrients. Immunonutrients are the subject of intensive investigation but have not been evaluated specifically in patients with AKI. We suggest a protocolized nutritional strategy delivering enteral nutrition whenever possible and providing at least the daily requirements of trace elements and vitamins.

Renal replacement strategies in the ICU

Acute renal failure (ARF) with the concomitant need for renal replacement therapy (RRT) is a common complication of critical care medicine that is still associated with high mortality. Different RRT strategies, like intermittent hemodialysis, continuous venovenous hemofiltration, or hybrid forms that combine the advantages of both techniques, are available and will be discussed in this article. Since a general survival benefit has not been demonstrated for either method, it is the task of the nephrologist or intensivist to choose the RRT strategy that is most advantageous for each individual patient. The underlying disease, its severity and stage, the etiology of ARF, the clinical and hemodynamic status of the patient, the resources available, and the different costs of therapy may all influence the choice of the RRT strategy. ARF, with its risk of uremic complications, represents an independent risk factor for outcome in critically ill patients. In addition, the early initiation of RRT with adequate doses is associated with improved survival. Therefore, the "undertreatment" of ARF should be avoided, and higher RRT doses than those in patients with chronic renal insufficiency, independent of whether convective or diffusive methods are used, are indicated in critically ill patients. However, clear guidelines on the dose of RRT and the timing of initiation are still lacking. In particular, it remains unclear whether hemodynamically unstable patients with septic shock benefit from early RRT initiation and the use of increased RRT doses, and whether RRT can lead to a clinically relevant removal of inflammatory mediators.

Renal replacement therapy in the treatment of acute renal failure-intermittent and continuous

Renal replacement therapy (RRT) is increasingly used in intensive care as acute renal failure (ARF) is a common and constantly increasing complication in this setting. Different forms of RRT such as intermittent hemodialysis, continuous hemofiltration, or hybrid forms, which combine advantages of both, are available and will be discussed in this article. As a general survival benefit for neither method has been demonstrated, it is the task of the nephrologist or intensivist to choose the RRT strategy that is most advantageous for each individual patient. The choice of RRT might depend not only on the underlying disease, the time course of the disease, the etiology of ARF, the actual clinical status of the patient but also on the resources available and the cost of therapy. An adequate dose of RRT seems to result in improved survival in patients with ARF. However, clear guidelines on the dose of RRT and the timing of initiation are still lacking. Moreover, it will be discussed whether patients with sepsis and septic shock benefit from early RRT initiation, the use of increased RRT doses, and increased removal of inflammatory mediators by RRT.

Reviews: The Current State of Nonuremic Applications for Extracorporeal Blood Purification

Despite the commonly accepted indications for hemodialysis and extracorporeal depuritive techniques, some clinicians have come to rely on blood purification for clinical states where the targeted substance for removal differs from uremic waste products. Over the last decade, a number of studies have emerged to help define the application of extracorporeal blood purification (ECBP) to these "nonuremic" indications. This review describes the application of extracorporeal blood purification in clinical states including sepsis, rhabdomyolysis, congestive heart failure, hepatic failure, tumor lysis syndrome, adult respiratory distress syndrome, intravenous contrast exposure, and lactic acidosis. Additional comments are provided to review existing literature on thermoregulation and osmoregulation, including acute brain injury.