Understanding urine output in critically ill patients

Urine output often is used as a marker of acute kidney injury but also to guide fluid resuscitation in critically ill patients. Although decrease of urine output may be associated to a decrease of glomerular filtration rate due to decrease of renal blood flow or renal perfusion pressure, neurohormonal factors and functional changes may influence diuresis and natriuresis in critically ill patients. The purpose of this review is to discuss the mechanisms of diuresis regulation, which may help to interpret the urine output in critically ill patients and the appropriate treatment to be initiated in case of changes in urine output

Management of hyperkalemia in the acutely ill patient.

PURPOSE:To review the mechanisms of action, expected efficacy and side effects of strategies to control hyperkalemia in acutely ill patients. METHODS:We searched MEDLINE and EMBASE for relevant papers published in English between Jan 1, 1938, and July 1, 2018, in accordance with the PRISMA Statement using the following terms: "hyperkalemia," "intensive care," "acute kidney injury," "acute kidney failure," "hyperkalemia treatment," "renal replacement therapy," "dialysis," "sodium bicarbonate," "emergency," "acute." Reports from within the past 10 years were selected preferentially, together with highly relevant older publications. RESULTS:Hyperkalemia is a potentially life-threatening electrolyte abnormality and may cause cardiac electrophysiological disturbances in the acutely ill patient. Frequently used therapies for hyperkalemia may, however, also be associated with morbidity. Therapeutics may include the simultaneous administration of insulin and glucose (associated with frequent dysglycemic complications), β-2 agonists (associated with potential cardiac ischemia and arrhythmias), hypertonic sodium bicarbonate infusion in the acidotic patient (representing a large hypertonic sodium load) and renal replacement therapy (effective but invasive). Potassium-lowering drugs can cause rapid decrease in serum potassium level leading to cardiac hyperexcitability and rhythm disorders. CONCLUSIONS:Treatment of hyperkalemia should not only focus on the ability of specific therapies to lower serum potassium level but also on their potential side effects. Tailoring treatment to the patient condition and situation may limit the risks

The strategy of antibiotic use in critically ill neutropenic patients

Suspicion of sepsis in neutropenic patients requires immediate antimicrobial treatment. The initial regimen in critically ill patients should cover both Gram-positive and Gram-negative pathogens, including Pseudomonas aeruginosa. However, the risk of selecting multidrug-resistant pathogens should be considered when using broad-spectrum antibiotics for a prolonged period of time. The choice of the first-line empirical drugs should take into account the underlying malignancy, local bacterial ecology, clinical presentation and severity of acute illness. This review provides an up-to-date guide that will assist physicians in choosing the best strategy regarding the use of antibiotics in neutropenic patients, with a special focus on critically ill patients, based on the above-mentioned considerations and on the most recent international guidelines and literature

Optimal design of nanomagnets for on-chip field gradients

The generation of localized magnetic field gradients by on-chip nanomagnets is important for a variety of technological applications, in particular for spin qubits. To advance beyond the empirical design of these nanomagnets, we propose a systematic and general approach based on the micromagnetic formulation of an optimal field gradient source. We study the different field configurations that can be realized and find out quantitatively the most suitable ferromagnetic layer geometries. Using micromagnetic simulations, we then investigate the minimum requirements for reaching magnetic saturation in these nanomagnets. In terms of either longitudinal or transverse field gradient, the results provide an optimal solution for uniform, saturated nanomagnets, where the magnetic material can be selected according to the strength of the external fields that can be used.Comment: 10 pages, 4 figures, supplemental material. All comments most welcom

The elusive task of biomarkers of renal injury

Neutrophil gelatinase-associated lipocalin (NGAL) is one of the most promising candidate biomarkers of renal injury, with expression in renal tissue increasing dramatically after ischemia-reperfusion injury but not in the case of pure pre-renal failure. In a recent issue of Critical Care, Di Somma and colleagues reported that NGAL could improve the classification of acute kidney injury compared with clinical assessment and showed that NGAL was associated with poor prognosis. NGAL may therefore carry different information than biomarkers of renal function. This study finally provides additional evidence for the highly complex relationship between renal function and renal injury

Pathophysiology of COVID-19-associated acute kidney injury

Although respiratory failure and hypoxaemia are the main manifestations of COVID-19, kidney involvement is also common. Available evidence supports a number of potential pathophysiological pathways through which acute kidney injury (AKI) can develop in the context of SARS-CoV-2 infection. Histopathological findings have highlighted both similarities and differences between AKI in patients with COVID-19 and in those with AKI in non-COVID-related sepsis. Acute tubular injury is common, although it is often mild, despite markedly reduced kidney function. Systemic haemodynamic instability very likely contributes to tubular injury. Despite descriptions of COVID-19 as a cytokine storm syndrome, levels of circulating cytokines are often lower in patients with COVID-19 than in patients with acute respiratory distress syndrome with causes other than COVID-19. Tissue inflammation and local immune cell infiltration have been repeatedly observed and might have a critical role in kidney injury, as might endothelial injury and microvascular thrombi. Findings of high viral load in patients who have died with AKI suggest a contribution of viral invasion in the kidneys, although the issue of renal tropism remains controversial. An impaired type I interferon response has also been reported in patients with severe COVID-19. In light of these observations, the potential pathophysiological mechanisms of COVID-19-associated AKI may provide insights into therapeutic strategies

Association between hypo- and hyperkalemia and outcome in acute heart failure patients : the role of medications

Background The interaction between chronic medications on admission and the association between serum potassium level and outcome in patients with acute heart failure (AHF) are unknown. Methods Observational intercontinental study of patients admitted with AHF. 15954 patients were included from 12 cohorts in 4 continents. Main outcome was 90-day mortality. Clinical presentation (medication use, hemodynamics, comorbidities), demographic, echocardiographic, and biochemical data on admission were recorded prospectively in each cohort, with prospective adjudication of outcomes. Results Positive and negative linear relationships between 90-day mortality and sK+ above 4.5 mmol/L (hyperkalemia) and below 3.5 mmol/L (hypo-kalemia) were observed. Hazard ratio for death was 1.46 [1.34-1.58] for hyperkalemia and 1.22 [1.06-1.40] for hypokalemia. In a fully adjusted model, only hyperkalemia remained associated with mortality (HR 1.03 [1.02-1.04] for each 0.1 mmol/l change of sK+ above 4.5 mmol/L). Interaction tests revealed that the association between hyperkalemia and outcome was significantly affected by chronic medications. The association between hyperkalemia and mortality was absent for patients treated with beta blockers and in those with preserved renal function. Conclusions In patients with AHF, sK+ > 4.5 mmol/L appears to be associated with 90-day mortality. B-blockers have potentially a protective effect in the setting of hyperkalemia.Peer reviewe

Days Spent at Home and Mortality After Critical Illness: A Cluster Analysis Using Nationwide Data

BACKGROUND: Beyond the question of short-term survival, days spent at home could be considered a patient-centered outcome in critical care trials. RESEARCH QUESTION: What are the days spent at home and healthcare trajectories during the year after surviving critical illness? STUDY DESIGN AND METHODS: Data were extracted on adult survivors spending at least two nights in a French intensive care unit (ICU) during 2018 who were treated with invasive mechanical ventilation and/or vasopressors or inotropes. Trauma, burn, organ transplant, stroke and neurosurgical patients were excluded. Stays at home, death, hospitalizations were reported before and after ICU stay, using state sequence analysis. An unsupervised clustering method was performed to identify cohorts based on post-ICU trajectories. RESULTS: Of 77,132 ICU survivors, 89% returned home. In the year post-discharge, these patients spent a median 330 (IQR 283-349) days at home. At one year, 77% of patients were still at home and 17% had died. Fifty-one percent had been re-hospitalized and 10% required a further ICU admission. Forty-eight percent used rehabilitation facilities and 5.7% hospital at home. Three clusters of patients with distinct post-ICU trajectories were identified. Patients in cluster 1 (68% of total) survived and spent most of the year at home (338 (323-354) days). Patients in cluster 2 (18%) had more complex trajectories but most could return home (91%), spending 242 (174-277) days at home. Patients in cluster 3 (14%) died with only 37% returning home for 45 (15-90) days. INTERPRETATION: Many patients had complex healthcare trajectories after surviving critical illness. Wide variations in the ability to return home after ICU discharge was observed between clusters, which represents an important patient-centered outcome