Is ultrafiltration volume a predictor of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass?

INTRODUCTION

Intraoperative ultrafiltration (UF) is a procedure used during cardiopulmonary bypass (CPB) to reduce haemodilution and prevent excessive blood transfusion. However, the effect of UF volume on acute kidney injury (AKI) is not well established, and the results are conflicting. Additionally, there are no set indications for applying UF during CPB.

METHODS

This retrospective study analysed 641 patients who underwent coronary artery bypass graft (CABG) surgery with CPB. Perioperative parameters were extracted from the patients' records, and the UF volume was recorded. Acute Kidney Injury Network classification was used to define AKI. Univariable and multivariable logistic regression models were used to predict AKI while controlling for confounding factors.

RESULTS

The study enrolled patients with a mean age of 58.8 ± 11.1 years, 39.2% of whom were female. AKI occurred in 22.5% of patients, with 16.1% (103) experiencing stage I and 6.4% (41) experiencing stage II. The results showed a significant association between UF volume and the risk of developing AKI, with higher UF volumes associated with a higher risk of AKI. In the multivariable analysis, the other predictors of AKI included age, lowest mean arterial pressure (MAP), and red blood cell (RBC) transfusion during CPB.

CONCLUSION

The predictors of postoperative AKI in coronary CABG patients were the volume of UF, age, MAP, and blood transfusion during CPB.

Epoprostenol (Prostacyclin Analog) as a Sole Anticoagulant in Continuous Renal Replacement Therapy for Critically Ill Children With Liver Disease: Single-Center Retrospective Study, 2010-2019

OBJECTIVES

Despite deranged coagulation, children with liver disease undergoing continuous renal replacement therapy (CRRT) are prone to circuit clotting. Commonly used anticoagulants (i.e., heparin and citrate) can have side effects. The aim of this study was to describe our experience of using epoprostenol (a synthetic prostacyclin analog) as a sole anticoagulant during CRRT in children with liver disease.

DESIGN

Single-center, retrospective study, 2010-2019.

SETTING

Sixteen-bedded PICU within a United Kingdom supra-regional center for pediatric hepatology.

PATIENTS

Children with liver disease admitted to PICU who underwent CRRT anticoagulation with epoprostenol.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Regarding CRRT, we assessed filter life duration, effective 60-hour filter survival, and effective solute clearance. We also assessed the frequency of major or minor bleeding episodes per 1,000 hours of CRRT, the use of platelet and RBC transfusions, and the frequency of hypotensive episodes per 1,000 hours of CRRT. In the 10 years 2010-2019, we used epoprostenol anticoagulation during 353 filter episodes of CRRT, lasting 18,508 hours, in 96 patients (over 108 admissions). Median (interquartile range [IQR]) filter life was 48 (IQR 32-72) hours, and 22.9% of filters clotted. Effective 60-hour filter survival was 60.5%.We identified that 5.9% of filters were complicated by major bleeding (1.13 episodes per 1,000 hr of CRRT), 5.1% (0.97 per 1,000 hr) by minor bleeding, and 11.6% (2.22 per 1,000 hr) by hypotension. There were no differences in filter life or clotting between patients with acute liver failure and other liver diseases; there were no differences in rates of bleeding, hypotension, or transfusion when comparing patients with initial platelets of ≤ 50 × 109 per liter to those with a higher initial count.

CONCLUSIONS

Epoprostenol, or prostacyclin, as the sole anticoagulant for children with liver disease receiving CRRT in PICU, results in a good circuit life, and complications such as bleeding and hypotension are similar to reports using other anticoagulants, despite concerns about coagulopathy in this cohort.

Reliable fluid-mechanical characterization of haemofilters: Addressing the deficiencies of current standards and practices

Facile methods for accurate fluid-mechanical characterization of haemofilters (HF) are indispensable for haemofiltration process improvements, equipment design/optimization, and reliable module specifications. Currently employed methods, implemented through specific experimental in vitro protocols, are assessed herein in detail, considering the conditions prevailing during haemofiltration. Minimum number of key parameters required to fully describe the common countercurrent flow field, in the HF active section, include membrane permeance K and friction coefficients in lumen and shell side (f_f and f_s ). It is shown that the countercurrent flow mode itself is incapable of yielding these parameters, based on externally measured flow rates and pressures. Similarly, the relevant ISO protocol is deficient as it can only provide rough underpredictions of permeance K. The causes of such inherent deficiencies of current standards and practices are analyzed. In contrast, a recently developed methodology, accounting for the (heretofore ignored) pressure drop in module headers and combining a mechanistic theoretical model with experimental data from 2 special haemofilter operating modes, yields an accurate determination of the key parameters (K, f_f , f_s ). Additionally, it permits a full description of flow field for Newtonian liquids, for both constant and axially varying viscosity in fiber-lumen due to the transmembrane flux. Development of new reliable standards is suggested, facilitated by the insights gained in this work.

Evaluation of Continuous Renal Replacement Therapy and Therapeutic Plasma Exchange, in Severe Sepsis or Septic Shock in Critically Ill Children

Background and objective: Severe sepsis and septic shock are life-threatening organ dysfunctions and causes of death in critically ill patients. The therapeutic goal of the management of sepsis is restoring balance to the immune system and fluid balance. Continuous renal replacement therapy (CRRT) is recommended in septic patients, and it may improve outcomes in patients with severe sepsis or septic shock. Therapeutic plasma exchange (TPE) is another extracorporeal procedure that can improve organ function by decreasing inflammatory and anti-fibrinolytic mediators and correcting haemostasis by replenishing anticoagulant proteins. However, research about sepsis and CRRT and TPE in children has been insufficient and incomplete. Therefore, we investigated the reliability and efficacy of extracorporeal therapies in paediatric patients with severe sepsis or septic shock. Materials and methods: We performed a multicentre retrospective study using data from all patients aged <18 years who were admitted to two paediatric intensive care units. Demographic data and reason for hospitalization were recorded. In addition, vital signs, haemogram parameters, and biochemistry results were recorded at 0 h and after 24 h of CRRT. Patients were compared according to whether they underwent CRRT or TPE; mortality between the two treatment groups was also compared. Results: Between January 2014 and April 2019, 168 septic patients were enrolled in the present study. Of them, 47 (27.9%) patients underwent CRRT and 24 underwent TPE. In patients with severe sepsis, the requirement for CRRT was statistically associated with mortality (p < 0.001). In contrast, the requirement for TPE was not associated with mortality (p = 0.124). Conclusion: Our findings revealed that the requirement for CRRT in patients with severe sepsis is predictive of increased mortality. CRRT and TPE can be useful techniques in critically ill children with severe sepsis. However, our results did not show a decrease of mortality with CRRT and TPE.

Propofol infusion syndrome: a structured literature review and analysis of published case reports

Propofol infusion syndrome is a rare, potentially fatal condition first described in children in the 1990s and later reported in adults. We provide a narrative review of what is currently known about propofol infusion syndrome, including a structured analysis of all published case reports; child and adult cases were analysed separately as propofol is no longer used for long-term sedation in children. The review contains an update on current knowledge of the pathophysiology of this condition along with recommendations for its diagnosis, prevention, and management. We reviewed 108 publications documenting 168 cases of propofol infusion syndrome. We evaluated clinical features and analysed factors influencing mortality in child and adult cases using separate multivariate analysis models. We used separate multiple linear regression models to analyse relationships between cumulative dose of propofol and the number of features seen and organ systems involved. Lipidaemia, fever, and hepatomegaly occurred more frequently in children than in adults, whilst rhabdomyolysis and hyperkalaemia were more frequent in adults. Mortality from propofol infusion syndrome is independently associated with fever and hepatomegaly in children, and electrocardiogram changes, hypotension, hyperkalaemia, traumatic brain injury, and a mean propofol infusion rate >5 mg kg^-1 h^-1 in adults. The cumulative dose of propofol was associated with an increased number of clinical features and the number of organ systems involved in adult cases only. Clinicians should consider propofol infusion syndrome in cases of unexplained metabolic acidosis, ECG changes, and rhabdomyolysis. We recommend early consideration of continuous haemofiltration in the management of propofol infusion syndrome.

Successful management of 70% acetic acid ingestion on the intensive care unit: A case report

Acetic acid is an organic acid available in concentrations from 2 to 80%. Whilst lower concentrations of 2-6% are more commonly used as the table top condiment, vinegar, much stronger solutions are regularly used in Eastern Europe as food preservatives and cleaning solutions. Oral ingestion of greater than 12% has been reported to cause haemolysis, renal failure, shock and death. Most reported cases of deliberate or accidental poisoning are from Russia and Eastern Europe in the 1980s, with very little currently in western publications. We present the case of a female patient who attempted suicide by drinking 250 ml of 70% acetic acid. Her widespread gastrointestinal injuries were managed conservatively, and despite suffering extensive upper airway and renal complications, she was successfully decannulated and discharged home after a prolonged intensive care and hospital stay.

Evaluating the safety and efficacy of regional citrate compared to systemic heparin as anticoagulation for continuous renal replacement therapy in critically ill patients: A service evaluation following a change in practice

Following the implementation of citrate anticoagulation for continuous renal replacement therapy, we evaluate its first year of use and compare it to the previously used heparin, to assess whether our patients benefit from the recently reported advantages of citrate. We retrospectively analysed 2 years of data to compare the safety and efficacy of citrate versus heparin. The results have shown that 43 patients received continuous renal replacement therapy with heparin, 37 patients with citrate. We found no significant difference in metabolic control of pH, urea and creatinine after 72 h. Filters anticoagulated with citrate had significantly longer median lifespan (33 h vs 17 h; p = 0.001), shorter downtime (0 h vs 5 h; p = 0.015) and less filter sets per patient day (0.37 vs 0.67; p = 0.002). Filters anticoagulated with heparin were commonly interrupted due to clotting (50% vs 16.4%), whereas filters anticoagulated with citrate were often stopped electively (53.4% vs 24.6%). Patients on heparin filters had significantly higher APPTs, some at potentially dangerous levels (>180 s), whilst patients on citrate filters had significantly higher levels of bicarbonate. Therefore, we conclude that citrate is superior in terms of safety and efficacy, with longer filter lifespan. It has become our first line anticoagulant for continuous renal replacement therapy.

Smoke on the water: A case report of chronic renal failure resulting from the ingestion of smoke machine fluid

We report the case of an 18-year-old male admitted to the Intensive Care Unit in Basingstoke and North Hampshire Hospital, who developed chronic kidney disease following the ingestion of smoke machine fluid. Smoke machine fluid may contain ethylene glycol, and a diagnosis of ethylene glycol toxicity with calcium oxalate nephropathy was made. This case resulted in a National Poisons Information Service internal review of the subject and a new TOXBASE entry for smoke machine fluid ingestion.

The effect of pulsatile cardiopulmonary bypass on the need for haemofiltration in patients with renal dysfunction undergoing cardiac surgery

OBJECTIVES

The aim of our study was to investigate the effects of pulsatile cardiopulmonary bypass (CPB) on renal function and the need for haemofiltration in patients with preoperative renal impairment undergoing cardiac surgery.

METHODS

Clinical data were collected prospectively for patients undergoing cardiac surgery with pulsatile CPB (Group A, n=66) and compared to matched patients with standard non-pulsatile CPB (Group B, n=66). Patients included in the study had mild renal impairment and at least moderate risk from surgery as defined by logistic EuroSCORE. Emergency operations were excluded.

RESULTS

Patients in Groups A and B had similar age (71 ± 10 versus 70 ± 10 years), sex distribution, mean preoperative renal function (creatinine clearance 63.9 ± 28 versus 67.7 ± 27.3 ml/min) and overall risk profile as predicted by the logistic EuroSCORE (8 ± 8.3 versus 11.05±13.3, p=0.122). Intraoperative variables were comparable with respect to bypass and cross-clamp times (96 ± 37 minutes and 64 ± 28 minutes versus 103 ± 40 minutes and 70 ± 33 minutes in Groups A and B, respectively). A smaller proportion of patients in Group A (4.5% versus 15%, p=0.076) required haemofiltration in the postoperative period. Postoperative mortality was low in both groups (Group A 1.54% versus Group B 3.03%, p=1.00).

CONCLUSION

Within the limitations imposed by retrospective analyses, our study demonstrates that pulsatile CPB may confer a reno-protective effect in higher-risk patients with pre-existing mild renal dysfunction undergoing cardiac surgery.

Effects of a novel cytokine haemoadsorbtion system on inflammatory response in septic shock after cephalic pancreatectomy - a case report

Severe sepsis and septic shock are associated with an inflammatory cascade that is primarily responsible for multiple organ dysfunction. To date, there are no specific treatments designed to modulate and rebalance inflammatory cytokines levels. We present a case of a 50 years old man with postoperative septic shock after undergoing cephalic pancreatectomy for a pancreatic cystic tumor. The use of a haemoadsorbtion device (CytoSorb^®) in combination with continuous veno-venous haemofiltration was associated with a decrease in TNFα, IL-1β and IFNγ and an increase in IL-10 levels measured before and after two consecutive procedures. The effect of CytoSorb^® on inflammatory cytokines translated into a more stable haemodynamic profile with a stable cardiac output and normalization of systemic vascular resistance index and decreased vasopressor requirements. Further prospective large clinical trials are required in order to determine the indications for CytoSorb^® and to evaluate the overall outcome.

Does diabetic status in the ICU predict haemofiltration requirement? The haemofiltration in the ICU and diabetic status (HIDS) study

Diabetes is already a major health burden and prevalence is expected to double by 2025. The impact of diabetes and clinical outcomes in the intensive care unit is an evolving area of research. This study seeks to identify whether diabetic status is an independent risk factor for haemofiltration. This is a retrospective cohort study. All unique patients from a seven-year period from 2004 to 2010 at a major intensive care unit in Melbourne, Australia were analysed using multivariate regression to look for an association between diabetic status and haemofiltration. After exclusion criteria there were 7262 patients, 1674 with a history of diabetes (median age of 69, 66.72% male) and 5588 without a history of diabetes (median age 64, 64.13% male). Diabetic status was an independent risk factor (odds ratio 1.401, 95% confidence interval 1.079 to 1.820, P=0.011) for haemofiltration. Further research may identify intensive care unit-based renoprotective measures specifically for patients with diabetes.

Perioperative considerations in a sickle cell patient undergoing cardiopulmonary bypass

An 11-year-old child, a known case of sickle cell anaemia with a history suggestive of sickling crisis in the past was scheduled for surgical pulmonary valvotomy. Pre-operative blood transfusion and hydroxyurea were administered. Pre-operative blood transfusion is indicated in sickle cell disease patients to raise the haematocrit level and lower sickle haemoglobin (HbS) levels. Before the start of cardiopulmonary bypass (CPB), exchange transfusion was performed to reduce HbS level and raise adult haemoglobin level. Hypothermia was prevented by employing normothermic CPB.

Ammonia clearance with haemofiltration in adults with liver disease

BACKGROUND & AIMS

Ammonia is recognized as a toxin central to complications of liver failure. Hyperammonaemia has important clinical consequences, but optimal means to reduce circulating levels are uncertain. In patients with liver disease, continuous renal replacement therapy (CRRT) with haemofiltration (HF) is often required to treat concurrent kidney injury, but its effects upon ammonia levels are poorly characterized. To evaluate the effect of HF at different treatment intensities on ammonia clearance (AC) and arterial ammonia concentration.

METHODS

Prospective study of adult patients with liver failure and arterial ammonia >100 μmol/L requiring CRRT using veno-venous HF. Arterial ammonia concentration and AC measured at 1 and 24 h after initiation of low (35 ml/kg/h) or high (90 ml/kg/h) filtration volume.

RESULTS

Twenty-four patients (10 acute liver failure, 10 chronic liver disease and 4 following liver resection) were studied. Clearance of urea and ammonia solutes correlated closely (r = 0.819, P = 0.007). Ammonia clearance correlated closely with ultrafiltration rate (r = 0.86, P < 0.001). At 1 h, AC was 39 (34-54) ml/min (low volume) vs 85 (62-105) ml/min (high volume) CRRT, (P < 0.001) and at 24 h 44 (34-63) vs 105 (82-109) ml/min, (P = 0.01). Overall, a 22% reduction in median arterial ammonia concentration was observed over 24 h of HF from 156 (137-176) to 122 (85-133) μmol/L, (P ≤ 0.0001).

CONCLUSION

Clinically significant ammonia clearance can be achieved in adult patients with hyperammonaemia utilizing continuous VVHF. Ammonia clearance is closely correlated with ultrafiltration rate. HF was associated with a fall in arterial ammonia concentration.

Citrate anticoagulation for continuous renal replacement therapy (CRRT) in patients with acute kidney injury admitted to the intensive care unit

Continuous forms of renal replacement therapy (CRRT) have become established as the treatment of choice for supporting critically ill patients with acute kidney injury. Typically, these patients have activation of the coagulation cascades, peripheral mononuclear cells and platelets, but also a reduction in natural anticoagulants, and are therefore prothrombotic. For continuous modes of renal replacement therapy to be effective, in terms of both effective solute clearance and also fluid removal, the extracorporeal circuits must operate continuously. Thus, preventing clotting in the CRRT circuit is a key goal to effective patient management. As these patients may also be at increased risk of bleeding, regional anticoagulation with citrate is increasing in popularity, particularly following the introduction of commercially available CRRT machines and fluids specifically designed for citrate anticoagulation. Although regional anticoagulation with citrate provides many advantages over other systemic anticoagulants, excess citrate may lead to both metabolic complications, ranging from acidosis to alkalosis and may also potentially expose patients to electrolyte disturbances due to hyper- and hyponatraemia and hyper- and hypocalcaemia.

Eighth World Congress of Intensive and Critical Care Medicine, 28 October-1 November 2001, Sydney, Australia: Harm minimization and effective risk management

The 8th World Congress saw the presentation of several late-breaking findings, such as the role of insulin in reducing mortality, and technologies such as vital microscopy. There were heated debates for and against the role of gastric tonometry, enteral nutrition, extracorporeal membrane oxygenation, the question of 'closed' or 'open' intensive care units, and several others. The overall message was the need to study outcomes and practise intensive care in a sensitive and humane fashion.

Continuous haemofiltration in the intensive care unit

Continuous renal replacement therapy (CRRT) was first described in 1977 for the treatment of diuretic-unresponsive fluid overload in the intensive care unit (ICU). Since that time this treatment has undergone a remarkable technical and conceptual evolution. It is now available in most tertiary ICUs around the world and has almost completely replaced intermittent haemodialysis (IHD) in some countries. Specially made machines are now available, and venovenous therapies that use blood pumps have replaced simpler techniques. Although, it remains controversial whether CRRT decreases mortality when compared with IHD, much evidence suggests that it is physiologically superior. The use of CRRT has also spurred renewed interest in the broader concept of blood purification, particularly in septic states. Experimental evidence suggests that this is a promising approach to the management of septic shock in critically ill patients. The evolution and use of CRRT is likely to continue and grow over the next decade.