The provision and practice of renal replacement therapy on adult intensive care units in the United Kingdom

Outcomes Associated With Intensive Care and Organ Support Among Patients With COVID-19: A Systematic Review and Meta-Analysis

BACKGROUND

Accurate accounting of coronavirus disease 2019 (COVID-19) critical care outcomes has important implications for health care delivery.

RESEARCH QUESTION

We aimed to determine critical care and organ support outcomes of intensive care unit (ICU) COVID-19 patients and whether they varied depending on the completeness of study follow-up or admission time period.

STUDY DESIGN AND METHODS

We conducted a systematic review and meta-analysis of reports describing ICU, mechanical ventilation (MV), renal replacement therapy (RRT), and extracorporeal membrane oxygenation (ECMO) mortality. A search was conducted using PubMed, Embase, and Cochrane databases.We included English language observational studies of COVID-19 patients, reporting ICU admission, MV, and ICU case fatality, published from December 1, 2019 to December 31, 2020. We excluded reports of less than 5 ICU patients and pediatric populations. Study characteristics, patient demographics, and outcomes were extracted from each article. Subgroup meta-analyses were performed based on the admission end date and the completeness of data.

RESULTS

Of 6,778 generated articles, 145 were retained for inclusion (n = 60,357 patients). Case fatality rates across all studies were 34.0% (95% CI = 30.7%, 37.5%, P < 0.001) for ICU deaths, 47.9% (95% CI = 41.6%, 54.2%, P < 0.001) for MV deaths, 58.7% (95% CI = 50.0%, 67.2%, P < 0.001) for RRT deaths, and 43.3% (95% CI = 31.4%, 55.4%, P < 0.001) for extracorporeal membrane oxygenation deaths. There was no statistically significant difference in ICU and organ support outcomes between studies with complete follow-up versus studies without complete follow-up. Case fatality rates for ICU, MV, and RRT deaths were significantly higher in studies with patients admitted before April 31st 2020.

INTERPRETATION

Coronavirus disease 2019 critical care outcomes have significantly improved since the start of the pandemic. Intensive care unit outcomes should be evaluated contextually (study quality, data completeness, and time) for the most accurate reporting and to effectively guide mortality predictions.

Renal impairment and its impact on clinical outcomes in patients who are critically ill with COVID-19: a multicentre observational study

Renal impairment is common in patients who are critically ill with coronavirus disease-19 (COVID-19). We examined the association between acute and chronic kidney disease with clinical outcomes in 372 patients with coronavirus disease-19 admitted to four regional intensive care units between 10 March 2020 and 31 July 2020. A total of 216 (58%) patients presented with COVID-19 and renal impairment. Acute kidney injury and/or chronic kidney disease was associated with greater in-hospital mortality compared with patients with preserved renal function (107/216 patients (50%) (95%CI 44-57) vs. 32/156 (21%) (95%CI 15-28), respectively; p < 0.001, relative risk 2.4 (95%CI 1.7-3.4)). Mortality was greatest in patients with renal transplants (6/7 patients (86%) (95%CI 47-100)). Mortality rates increased in patients with worsening renal injury according to the Kidney Disease: Improving Global Outcomes classification: stage 0 mortality 33/157 patients (21%) (95%CI 15-28) vs. stages 1-3 mortality 91/186 patients (49%) (95%CI 42-56); p < 0.001, relative risk 2.3 (95%CI 1.7-3.3). Survivors were less likely to require renal replacement therapy compared with non-survivors (57/233 patients (24%) vs. 64/139 patients (46%), respectively; p < 0.001, relative risk 1.9 (95%CI 1.4-2.5)). One-fifth of survivors who required renal replacement therapy acutely in intensive care continued to require renal support following discharge. Our data demonstrate that renal impairment in patients admitted to intensive care with COVID-19 is common and is associated with a high mortality and requirement for on-going renal support after discharge from critical care. Our findings have important implications for future pandemic planning in this patient cohort.

Antimicrobial dosing in critically ill patients with sepsis-induced acute kidney injury

Severe sepsis often leads to multiple organ dysfunction syndromes (MODS) with acute kidney injury (AKI). AKI affects approximately, 35% of Intensive Care Unit patients, and most of these are due to sepsis. Mortality rate of sepsis-induced AKI is high. Inappropriate use of antimicrobials may be responsible for higher therapeutic failure, mortality rates, costs and toxicity as well as the emergence of resistance. Antimicrobial treatment is particularly difficult due to altered pharmacokinetic profile, dynamic changes in patient's clinical status and, in many cases, need for renal replacement therapy. This article aims to describe the appropriate antimicrobial dosing and reviews the factors contributing to the difficulties in establishing precise guidelines for antimicrobial dosing in sepsis-induced AKI patients.

SEARCH STRATEGY

Text material was collected by systematic search in PubMed, Google (1978-2013) for original articles.

Circuit life versus bleeding risk: the impact of achieved activated partial thromboplastin time versus achieved filtration fraction

Whilst prolonging hemofilter (circuit) life, heparin increases bleeding risk. The impact of achieved activated partial thromboplastin time (APTT) on circuit life and bleeding risk has not been assessed in a modern critically ill cohort. Lowering filtration fraction may be an alternative means of prolonging circuit life, but is often overlooked in critical care. An observational study of 309 consecutive circuits in a general intensive care unit was conducted using a wide target APTT range. Multilevel modeling was used to predict circuit life and bleeding according to achieved APTT and filtration fraction. Independent predictors of circuit failure (i.e. unplanned ending of treatment) included filtration fraction (P<0.001, HR 1.07 per 1% increase), peak APTT (P<0.001, HR 0.8 per 10 s increase or 0.3 APTR increase) and baseline PT (P=0.014, HR 0.91 for every 50% increase). The only significant predictor of bleeding was peak APTT (P=0.017, OR 1.05 per 10 s increase). Every 10 s APTT increase was associated with a 20% reduction in circuit failure, but a 5% increase in hemorrhage. A 3% reduction in filtration fraction was associated with the same improvement in circuit life as a 10 s increase in APTT. Increasing APTT prolongs circuit life but carries a substantial risk of bleeding even in modern practice. Filtration fraction has a large impact on circuit life in the critically ill: a 3% reduction in filtration fraction, e.g. by increasing blood flow or delivering some of the clearance via dialysis, would be expected to reduce circuit failure as much as a 10 s increase in APTT.

Heparin algorithm for anticoagulation during continuous renal replacement therapy

Premature circuit clotting is a problem during continuous renal replacement therapy. We describe an algorithm for individualised anticoagulation with unfractionated heparin based on the patient's risk of bleeding and previous circuit life. The algorithm allows effective and safe nurse-led anticoagulation during continuous renal replacement therapy.

Anticoagulant Use in Renal Replacement Therapy in the Mid Trent Critical Care Network: A Survey of Practice

Anticoagulant drug use is one of the methods employed to prolong filter life during renal replacement therapy in the critically ill patient. In the Mid Trent Critical Care network, a variety of anticoagulant regimens are used with varying efficacy. This is a retrospective survey of anticoagulant regimens, comparing mechanical filter life, blood product use and documented complications in the five largest units using renal replacement therapy in the region, and to evaluate how effective our regimens were compared to standards defined in the medical literature.

Patient flow from critical care to renal services: a year-long survey in a critical care network

BACKGROUND

The NSF for Renal Services stresses the importance of collaboration between renal services and critical care networks in managing patients with acute renal failure in the most clinically appropriate setting. Anecdotal evidence in our region suggested that some patients were remaining on critical care inappropriately because of a lack of capacity for step-down care in local renal units.

AIM

To determine the number of extra days patients spend on critical care receiving single-organ renal support before transfer to a renal unit.

DESIGN

Prospective, multi-centre, service evaluation.

METHODS

Prospective data were collected over a one-year period by either daily telephone calls or bedside review. Follow-up data were retrieved from electronic and patient records.

RESULTS

Five hundred and forty-two patients received renal replacement therapy (RRT) in critical care. With 68 (12.5%) patients already receiving RRT for end-stage renal failure, this gave an incidence of new RRT on critical care of 234 per million population per year. The median duration of RRT on critical care was 4 days (range 1-30). One hundred and twenty-seven patients (23%) were discharged from critical care still requiring RRT. A period of single-organ renal support (median 2 days, range 1-8) was provided to 74 of these patients (58%) using 113 critical care bed days.

DISCUSSION

Over half of patients receiving RRT on discharge from critical care in our network received a short period of single-organ renal support before step-down. This may represent either delayed discharge from critical care or a potential opportunity for care in an alternative high-dependency facility.

Dosing Regimes for Antimicrobials during Continuous Veno-Venous Haemofiltration (CVVH)

The pharmacokinetic profile of antibiotics used in critically ill patients during continuous haemofiltration is different both from healthy people and from stable patients on long-term dialysis. This article reviews the patient-related, drug-related and haemofiltration-related variables influencing drug elimination in this group of patients, and provides specific recommendations for antibiotic dosing for different classes of antibiotics. Loading doses do not need to be altered. Subsequent dose adjustment should be based on the estimated ultrafiltration capacity of the renal replacement technique and the degree of extracorporeal clearance. A table of recommended doses is provided.

Renal replacement therapy for acute renal failure: a survey of practice in adult intensive care units in the United Kingdom

This study surveyed current practice in adult intensive care units in the United Kingdom in three key areas of renal replacement therapy when used for acute renal failure: type of therapy used, typical treatment dose and anticoagulation. Responses were received from 303 (99%) of the 306 intensive care units. 269 units (89%) provide renal replacement therapy for acute renal failure. Most (65%) use continuous veno-venous haemofiltration as first-line therapy in the majority of patients, though continuous veno-venous haemodiafiltration is used by 31% of units. For haemofiltration, the median typical treatment dose (interquartile range [range]) is 32 ml.kg(-1).h(-1) (28.6-35.7 [14.3-85.7]), with 49% using a treatment dose of 35 ml.kg(-1).h(-1) or greater. For haemodiafiltration, the median typical treatment dose (interquartile range [range]) is 44 ml.kg(-1).h(-1) (28.6-57.1 [21.4-120.7]), with 67% using a treatment dose of 35 ml.kg(-1).h(-1) or greater. The vast majority of intensive care units use intravenous unfractionated heparin (96%) or epoprostenol (88%) for anticoagulation. Dosage and monitoring of these two agents vary markedly between units. No units use citrate anticoagulation. These results reveal a wide variety of practice in the delivery of renal replacement therapy between intensive care units in the United Kingdom.

Intermittent versus continuous renal replacement therapy: a matter of controversy

BACKGROUND

Acute Renal Failure (ARF) requiring some form of replacement therapy is a frequent complication in the critically ill patient. Despite potential therapeutic advantages the expectation of an improvement in patient outcomes using Continuous Renal Replacement Therapy (CRRT) compared to conventional Intermittent Haemodialysis (IHD) remains controversial.

AIMS AND METHOD

This article will review the literature on the issues surrounding the use of IHD versus CRRT in the management of the critically ill patient. Articles were selected according to level of evidence with priority given to meta-analyses and randomised controlled trials.

DISCUSSION

Several operational features of CRRT allow this technique to be tolerated more easily in critical illness than IHD. The gradual removal of fluid reduces the incidence of hypotension and the risk of volume overload. Decreased variability in the concentration of solutes enables greater azotemia control. However, CRRT is required to operate uninterrupted to achieve a treatment dose that is equivalent to a conventional IHD treatment schedule. In the absence of definitive evidence to validate superior patient survival and return of renal function there is disagreement as to the most appropriate form of Renal Replacement Therapy (RRT) for the critically ill patient. The introduction of 'hybrid' therapies offers a further alternative treatment strategy, which combine favourable aspects of IHD and CRRT.

CONCLUSION

The decision to use IHD or CRRT should be guided by the therapeutic needs of the patient rather than the operational differences between the two techniques. The resources and expertise available at the organisation are also important in determining the mode best able to manage the critically ill patient at any stage and may change according to the severity of illness. The emergence of hybrid therapies provides a compromise option which encompasses many of the features of both systems, but does not embrace all options of either approach.

Maintaining the CRRT circuit: non-anticoagulant alternatives

Prevention of clotting is an important factor in continuous renal replacement therapy (CRRT) to ensure that solute clearance, electrolytes and acid base and fluid balance are controlled. This article will focus attention on the components and design of the CRRT circuit, identifying strategies in the literature which may promote circuit life. It is important that the CRRT circuit incorporates biocompatible materials and is designed in a way which limits turbulent blood flow. Premature clotting is also more likely to occur when blood flow through the circuit is interrupted or sluggish as a result of poor vascular access, or when there is increased resistance or obstruction in the circuit. The pre-dilution method of fluid replacement reduces blood viscosity inside the haemofilter and assists in delaying the onset of blood clots by limiting the potential for haemoconcentration. The monitoring and adjustment of the blood level inside the venous bubble or air trap can lessen the effect of blood-air contact and protect the site from excessive clotting. A number of other factors are also considered important as predictors of circuit life in the operation and management of the circuit. They include the choice of access site and design configuration of the catheter device, and the level of competency of nursing staff preparing and monitoring circuit function. Whilst the value of intermittent saline flushing has not been proven to be of benefit in promoting circuit life, it remains to be determined whether the choice in the CRRT mode affects circuit life differently. In conclusion, specific measures in the application of CRRT besides anticoagulation therapy can influence the development of blood clots and the duration of circuit life. This requires the development of evidence-based practice guidelines which include strategies that are known to promote circuit life.

Anticoagulation in CRRT: Agents and strategies in Australian ICUs

BACKGROUND

Continuous Renal Replacement Therapy (CRRT) should ideally operate with as little interruption as possible. The majority of circuit terminations occur due to clotting. The Longevity of CRRT is able to be improved when the extracorporeal circuit is anticoagulated.

AIMS

This article willt focus attention on anticoagulant agents used in Australian intensive care units (ICU) to prevent clotting in the CRRT circuit.

DISCUSSION

Anticoagulants reviewed include unfractionated or standard heparin, regional heparinisation, low-molecular weight heparins and heparinoids, regional citrate, platelet-inhibiting agents (prostacyclin), thrombin antagonists (recombinant hirudin) and therapy with no anticoagulant use. Each type of anticoagulant was reviewed for mode of action, the method of delivery and how the effect is monitored. Circuit life and the incidence of bleeding were considered as the principle end points in selecting therapy, as well as side-effects with administration such as metabolic disturbances, contraindications to use including allergy and ease of use in the clinical environment.

CONCLUSION

No approach to anticoagulation has yet been reported to be as successful in extending circuit life, whilst remaining inexpensive, easy to manage and easy to reverse, as unfractionated heparin. Certain patient conditions may preclude the use of heparin, such as heparin-induced thrombocytopenia (HIT); then heparinoids, thrombin antagonists and sodium citrate are suggested as alternatives. Regional citrate reduces haemorrhagic complications in patients who have coagulation disorders or are at risk of bleeding. Clinical experience with various agents and strategies should also influence choice. The option of no anticoagulant may be appropriate in selected patients rather than more expensive and less familiar drugs.

Early hemodynamic improvement is a prognostic marker in patients treated with continuous CVVHDF for acute renal failure

We examined whether hemodynamic improvement after high-flow hemofiltration predicts survival in patients treated with standard continuous renal replacement therapy (CRRT). This was a prospective, observational cohort study of 169 patients, measuring the mean arterial pressure (MAP) and norepinephrine (NE) dosage before and 24 hours after CRRT. Responders were defined as having a 20% reduction in NE dosage or a 20% rise in MAP with no increase in NE, compared with nonresponders. Patients were considered to be unstable if they were receiving NE or their MAP was lower than 60 mm Hg before CRRT. Of the 169 patients, 68% were men; mean age was 53.8 years (52.7 to 54.9), with a mean Acute Physiology and Chronic Health Evaluation (APACHE) II at admission of 21.8 (21.2 to 22.3), of whom 114 were unstable at the start of CRRT. Overall mortality rate 15 days after the end of CRRT was 54.3% (57.7% in stable vs. 52.9% in unstable patients, p = NS). There were 99 responders and 70 nonresponders, the only differences being NE dosage (higher in responders, p < 0.01) and mortality rate (responders 30% vs. nonresponders 74.7%, p < 0.001). In unstable patients, mortality rate was 30% in responders versus 87% in nonresponders (p < 0.001) (72% sensitivity and 86% specificity for predicting death). Logistic regression analysis showed that the only variables associated with death were APACHE II at admission (OR, 1.06; 95% CI, 1.0 to 1.12), percent creatinine decrease (OR, 0.98; CI, 0.96 to 1.0), and lack of hemodynamic response to CRRT (OR, 7.04; CI, 3.3 to 15.02). Hemodynamic improvement after 24-hour CRRT is a strong predictor of survival.

The epidemiology of acute renal failure in the world

PURPOSE OF REVIEW

The aim of this article is to describe our current understanding of the epidemiology of acute renal failure, especially in severe cases requiring renal replacement therapy. Some data from an international observational study (the Beginning and Ending Supportive Therapy (BEST) for the kidney study) are also presented.

RECENT FINDINGS

Multiple epidemiological studies for acute renal failure have been conducted in different populations using various criteria and reported a wide range of incidence and mortality. In several multicenter studies reporting the incidence of renal replacement therapy requirement in a general intensive care unit population, however, renal replacement therapy requirement and hospital mortality was quite similar among the studies, approximately 4% and 60%, respectively. In North and South America, nephrologists typically manage acute renal failure patients with intermittent renal replacement therapy. On the other hand, in Asia, Australia and Europe, intensivists are commonly responsible for managing these patients with continuous renal replacement therapy.

SUMMARY

Although the epidemiology of acute renal failure is varied among regions and centers, the average incidence of renal replacement therapy requirement and hospital mortality in critical illness are similar in multicenter studies. Continuous renal replacement therapy is gaining popularity and intensivists are becoming responsible for managing patients with it. More studies are needed to understand acute renal failure epidemiology worldwide. To conduct such studies, consensus criteria for acute renal failure and a well performed acute renal failure-specific severity score will be required.

Survival by Dialysis Modality in Critically Ill Patients with Acute Kidney Injury

Among critically ill patients, acute kidney injury (AKI) requiring dialysis is associated with mortality rates generally in excess of 50%. Continuous renal replacement therapies (CRRT) often are recommended and widely used, although data to support its superiority over intermittent hemodialysis (IHD) are lacking. Data from the Program to Improve Care in Acute Renal Disease (PICARD), a multicenter observational study of AKI, were analyzed. Among 398 patients who required dialysis, the risk for death within 60 d was examined by assigned initial dialysis modality (CRRT [n = 206] versus IHD [n = 192]) using standard Kaplan-Meier product limit estimates, proportional hazards ("Cox") regression methods, and a propensity score approach to account for selection effects. Crude survival rates were lower for patients who were treated with CRRT than IHD (survival at 30 d 45 versus 58%; P = 0.006). Adjusted for age, hepatic failure, sepsis, thrombocytopenia, blood urea nitrogen, and serum creatinine and stratified by site, the relative risk for death associated with CRRT was 1.82 (95% confidence interval 1.26 to 2.62). Further adjustment for the propensity score did not materially alter the association (relative risk 1.92; 95% confidence interval 1.28 to 2.89). Among critically ill patients with AKI, CRRT was associated with increased mortality. Although the results could reflect residual confounding by severity of illness, these data provide no evidence for a survival benefit afforded by CRRT. Larger, prospective, randomized clinical trials to compare CRRT and IHD in severe AKI are needed.