Mechanical ventilation and acute renal failure

Ventilator-induced Lung Injury Promotes Inflammation within the Pleural Cavity

Mechanical ventilation contributes to the morbidity and mortality of patients in intensive care, likely through the exacerbation and dissemination of inflammation. Despite the proximity of the pleural cavity to the lungs and exposure to physical forces, little attention has been paid to its potential as an inflammatory source during ventilation. Here, we investigate the pleural cavity as a novel site of inflammation during ventilator-induced lung injury. Mice were subjected to low or high tidal volume ventilation strategies for up to 3 hours. Ventilation with a high tidal volume significantly increased cytokine and total protein levels in BAL and pleural lavage fluid. In contrast, acid aspiration, explored as an alternative model of injury, only promoted intraalveolar inflammation, with no effect on the pleural space. Resident pleural macrophages demonstrated enhanced activation after injurious ventilation, including upregulated ICAM-1 and IL-1β expression, and the release of extracellular vesicles. In vivo ventilation and in vitro stretch of pleural mesothelial cells promoted ATP secretion, whereas purinergic receptor inhibition substantially attenuated extracellular vesicles and cytokine levels in the pleural space. Finally, labeled protein rapidly translocated from the pleural cavity into the circulation during high tidal volume ventilation, to a significantly greater extent than that of protein translocation from the alveolar space. Overall, we conclude that injurious ventilation induces pleural cavity inflammation mediated through purinergic pathway signaling and likely enhances the dissemination of mediators into the vasculature. This previously unidentified consequence of mechanical ventilation potentially implicates the pleural space as a focus of research and novel avenue for intervention in critical care.

Acute Kidney Injury in Neonatal Intensive Care Unit: Epidemiology, Diagnosis and Risk Factors

Acute kidney injury (AKI) is associated with long-term consequences and poor outcomes in the neonatal intensive care unit. Its precocious diagnosis represents one of the hardest challenges in clinical practice due to the lack of sensitive and specific biomarkers. Currently, neonatal AKI is defined with urinary markers and serum creatinine (sCr), with limitations in early detection and individual treatment. Biomarkers and risk factor scores were studied to predict neonatal AKI, to early identify the stage of injury and not the damage and to anticipate late increases in sCr levels, which occurred when the renal function already began to decline. Sepsis is the leading cause of AKI, and sepsis-related AKI is one of the main causes of high mortality. Moreover, preterm neonates, as well as patients with post-neonatal asphyxia or after cardiac surgery, are at a high risk for AKI. Critical patients are frequently exposed to nephrotoxic medications, representing a potentially preventable cause of AKI. This review highlights the definition of neonatal AKI, its diagnosis and new biomarkers available in clinical practice and in the near future. We analyze the risk factors involving patients with AKI, their outcomes and the risk for the transition from acute damage to chronic kidney disease.

Prospective Multicenter Study on Early Proximal Tubular Injury in COVID-19-Related Acute Respiratory Distress Syndrome

Introduction

During COVID-19, renal impairment is associated with poor prognosis in intensive care unit (ICU). We aimed to assess the existence and incidence of early renal dysfunction and its prognostic value in patients with COVID-19-related acute respiratory distress syndrome (ARDS).

Methods

In this prospective multicenter study, patients aged over 18 years with invasive mechanical ventilation (MV) for ARDS were enrolled in 3 ICUs. Precise evaluation of renal dysfunction markers, including urinary protein electrophoresis (UPE) and quantification, was performed within 24 hours after MV onset.

Results

From March 2020 to December 2021, 135 patients were enrolled as follows: 100 with COVID-19 ARDS and 35 with non-COVID-19 ARDS. UPE found more tubular dysfunction in patients with COVID-19 (68% vs. 21.4%, P < 0.0001) and more normal profiles in patients without COVID-19 (65.0% vs. 11.2%, P = 0.0003). Patients with COVID-19 significantly displayed early urinary leakage of tubular proteins such as beta-2-microglobulin (ß2m) and free light chains, tended to display acute kidney injury (AKI) more frequently (51.0% vs. 34.3%, P = 0.088), had longer MV (20 vs. 9 days, P < 0.0001) and longer ICU stay (26 vs. 15 days, P < 0.0001). In COVID-19 ARDS, leakage of free lambda light chain was associated with the onset of Kidney Disease: Improving Global Outcomes (KDIGO) ≥2 AKI (odds ratio [OR]: 1.014, 95% confidence interval [CI] 1.003-1.025, P = 0.011).

Conclusion

Patients with COVID-19-related ARDS display a proximal tubular dysfunction before the onset of AKI, which predicts AKI. Proximal tubular damage seems an important mechanism of COVID-19-induced nephropathy. Analysis of urinary proteins is a reliable noninvasive tool to assess proximal tubular dysfunction in the ICU.

Impact of positive end-expiratory pressure on renal resistive index in mechanical ventilated patients

PURPOSE

Growing evidence shows the complex interaction between lung and kidney in critically ill patients. The renal resistive index (RRI) is a bedside measurement of the resistance of the renal blood flow and it is correlated with kidney injury. The positive end-expiratory pressure (PEEP) level could affect the resistance of renal blood flow, so we assumed that RRI could help to monitoring the changes in renal hemodynamics at different PEEP levels. Our hypothesis was that the RRI at ICU admission could predict the risk of acute kidney injury in mechanical ventilated critically ill patients.

METHODS

We performed a prospective study including 92 patients requiring mechanical ventilation for ≥ 48 h. A RRI ≥ 0.70, was deemed as pathological. RRI was measured within 24 h from ICU admission while applying 5,10 and 15 cmH2O of PEEP in random order (PEEP trial).

RESULTS

Overall, RRI increased from 0.62 ± 0.09 at PEEP 5 to 0.66 ± 0.09 at PEEP 15 (p < 0.001). The mean RRI value during the PEEP trial was able to predict the occurrence of AKI with AUROC = 0.834 [95%CI 0.742-0.927]. Patients exhibiting a RRI ≥ 0.70 were 17/92(18%) at PEEP 5, 28/92(30%) at PEEP 10, 38/92(41%) at PEEP 15, respectively. Thirty-eight patients (41%) exhibited RRI ≥ 0.70 at least once during the PEEP trial. In these patients, AKI occurred in 55% of the cases, versus 13% remaining patients, p < 0.001.

CONCLUSIONS

RRI seems able to predict the risk of AKI in mechanical ventilated patients; further, RRI values are influenced by the PEEP level applied.

TRIAL REGISTRATION

Clinical gov NCT03969914 Registered 31 May 2019.

The impact of inhalation injury on fluid resuscitation in major burn patients: a 10-year multicenter retrospective study

BACKGROUND

It remains unclear whether additional fluid supplementation is necessary during the acute resuscitation period for patients with combined inhalational injury (INHI) under the guidance of the Third Military Medical University (TMMU) protocol.

METHODS

A 10-year multicenter, retrospective cohort study, involved patients with burns ≥ 50% total burn surface area (TBSA) was conducted. The effect of INHI, INHI severity, and tracheotomy on the fluid management in burn patients was assessed. Cumulative fluid administration, cumulative urine output, and cumulative fluid retention within 72 h were collected and systematically analyzed.

RESULTS

A total of 108 patients were included in the analysis, 85 with concomitant INHI and 23 with thermal burn alone. There was no significant difference in total fluid administration during the 72-h post-burn between the INHI and non-INHI groups. Although no difference in the urine output and fluid retention was shown in the first 24 h, the INHI group had a significantly lower cumulative urine output and a higher cumulative fluid retention in the 48-h and 72-h post-burn (all p < 0.05). In addition, patients with severe INHI exhibited a significantly elevated incidence of complications (Pneumonia, 47.0% vs. 11.8%, p = 0.012), (AKI, 23.5% vs. 2.9%, p = 0.037). For patients with combined INHI, neither the severity of INHI nor the presence of a tracheotomy had any significant influence on fluid management during the acute resuscitation period.

CONCLUSIONS

Additional fluid administration may be unnecessary in major burn patients with INHI under the guidance of the TMMU protocol.

Patterns of Multiple Organ Dysfunction and Renal Recovery in Critically Ill Children and Young Adults Receiving Continuous Renal Replacement Therapy

OBJECTIVES

Acute kidney injury requiring dialysis (AKI-D) commonly occurs in the setting of multiple organ dysfunction syndrome (MODS). Continuous renal replacement therapy (CRRT) is the modality of choice for AKI-D. Mid-term outcomes of pediatric AKI-D supported with CRRT are unknown. We aimed to describe the pattern and impact of organ dysfunction on renal outcomes in critically ill children and young adults with AKI-D.

DESIGN

Retrospective cohort.

SETTING

Two large quarternary care pediatric hospitals.

PATIENTS

Patients 26 y old or younger who received CRRT from 2014 to 2020, excluding patients with chronic kidney disease.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Organ dysfunction was assessed using the Pediatric Logistic Organ Dysfunction-2 (PELOD-2) score. MODS was defined as greater than or equal to two organ dysfunctions. The primary outcome was major adverse kidney events at 30 days (MAKE30) (decrease in estimated glomerular filtration rate greater than or equal to 25% from baseline, need for renal replacement therapy, and death). Three hundred seventy-three patients, 50% female, with a median age of 84 mo (interquartile range [IQR] 16-172) were analyzed. PELOD-2 increased from 6 (IQR 3-9) to 9 (IQR 7-12) between ICU admission and CRRT initiation. Ninety-seven percent of patients developed MODS at CRRT start and 266 patients (71%) had MAKE30. Acute kidney injury (adjusted odds ratio [aOR] 3.55 [IQR 2.13-5.90]), neurologic (aOR 2.07 [IQR 1.15-3.74]), hematologic/oncologic dysfunction (aOR 2.27 [IQR 1.32-3.91]) at CRRT start, and progressive MODS (aOR 1.11 [IQR 1.03-1.19]) were independently associated with MAKE30.

CONCLUSIONS

Ninety percent of critically ill children and young adults with AKI-D develop MODS by the start of CRRT. Lack of renal recovery is associated with specific extrarenal organ dysfunction and progressive multiple organ dysfunction. Currently available extrarenal organ support strategies, such as therapeutic plasma exchange lung-protective ventilation, and other modifiable risk factors, should be incorporated into clinical trial design when investigating renal recovery.

Controlled Mechanical Ventilation in Critically Ill Patients and the Potential Role of Venous Bagging in Acute Kidney Injury

A very low incidence of acute kidney injury (AKI) has been observed in COVID-19 patients purposefully treated with early pressure support ventilation (PSV) compared to those receiving mainly controlled ventilation. The prevention of subdiaphragmatic venous congestion through limited fluid intake and the lowering of intrathoracic pressure is a possible and attractive explanation for this observed phenomenon. Both venous congestion, or "venous bagging", and a positive fluid balance correlate with the occurrence of AKI. The impact of PSV on venous return, in addition to the effects of limiting intravenous fluids, may, at least in part, explain this even more clearly when there is no primary kidney disease or the presence of nephrotoxins. Optimizing the patient-ventilator interaction in PSV is challenging, in part because of the need for the ongoing titration of sedatives and opioids. The known benefits include improved ventilation/perfusion matching and reduced ventilator time. Furthermore, conservative fluid management positively influences cognitive and psychiatric morbidities in ICU patients and survivors. Here, it is hypothesized that cranial lymphatic congestion in relation to a more positive intrathoracic pressure, i.e., in patients predominantly treated with controlled mechanical ventilation (CMV), is a contributing risk factor for ICU delirium. No studies have addressed the question of how PSV can limit AKI, nor are there studies providing high-level evidence relating controlled mechanical ventilation to AKI. For this perspective article, we discuss studies in the literature demonstrating the effects of venous congestion leading to AKI. We aim to shed light on early PSV as a preventive measure, especially for the development of AKI and ICU delirium and emphasize the need for further research in this domain.

The effect of intraoperative positive end expiratory pressure and tidal volume on postoperative acute kidney injury after orthopedic surgery

BACKGROUND

To test whether higher intraoperative PEEP levels and/or higher TV levels are associated with higher incidence of postoperative AKI within the first postoperative week, in adult patients having orthopedic surgeries under general anesthesia.

METHODS

We conducted a sub analysis of a non-randomized alternating intervention cross over study performed in patients undergoing orthopedic surgery under general anesthesia at Cleveland Clinic, Cleveland, OH. We included four different combinations of PEEP (5 or 8 cm H2 O) and TV (6 or 10 mL/kg of PBW) that alternated each week in the six orthopedic operating rooms. Our primary outcome was postoperative AKI defined by the KDIGO criteria with baseline creatinine as the closest preoperative value to the time of surgery obtained within 30 days and postoperative value as the highest creatinine value within 7 days after surgery. Secondary outcome was the maximum postoperative in-hospital creatinine level within seven postoperative days.

MAIN RESULTS

A total of 1933 patients were included in the analysis. The incidence of AKI was 6.8% in the study population and similar in high TV versus low TV group and high PEEP versus low PEEP group. Neither TV nor PEEP significantly impacted AKI incidence. The estimated odds ratio of AKI comparing TV = 6 mL/kg to TV = 10 mL/kg was 0.96 (97.5% CI: 0.63, 1.46; p = .811); while the estimated odds ratio of AKI comparing PEEP = 5cm H2 O to PEEP = 8cm H2 O was 0.92 (97.5% CI: 0.60, 1.39; p = .623). No interaction was found between TV and PEEP on AKI. Additionally, neither TV nor PEEP had a significant effect on the seven postoperative day creatinine levels.

CONCLUSION

Higher levels of PEEP or TV during mechanical ventilation in adult patients undergoing orthopedic surgeries under general anesthesia do not increase the odds of developing postoperative AKI within the narrow limits studied.

Geniposide ameliorates acute kidney injury via enhancing the phagocytic ability of macrophages towards neutrophil extracellular traps

Acute kidney injury (AKI) is a clinically serious disorder associated with high mortality rates and an increased risk of progression to end-stage renal disease. As an essential supportive treatment for patients with respiratory failure, mechanical ventilation not only save many critically ill patients, but also affect glomerular filtration function by changing renal hemodynamics, neurohumoral and positive end-expiratory pressure, eventually leading to AKI. AMP-activated protein kinase (AMPK), a crucial energy homeostasis regulator, could enhance macrophage phagocytic ability and inhibit inflammation, but whether it can engulf neutrophil extracellular traps (NETs) and alleviate mechanical ventilation-associated AKI is still unclear. In this study, we found that geniposide significantly ameliorated histopathological damage, reduced serum Cre and BUN levels. Besides, geniposide can also induce AMPK activation and enhance macrophage phagocytic ability toward NETs. Moreover, geniposide can markedly reduce the levels of high mobility group box 1 (HMGB1), and these effects were dependent on AMPK-PI3K/Akt signaling. Altogether, these results indicated that geniposide promoted macrophage efferocytosis by inducing AMPK-PI3K/Akt signaling activation, clearing NETs and ameliorating AKI.

Development of a nomogram model for the early prediction of sepsis-associated acute kidney injury in critically ill patients

Sepsis-associated acute kidney injury is a common complication of sepsis, but it is difficult to predict sepsis-associated acute kidney injury. In this retrospective observational study, adult septic patients were recruited from the MIMIC-III database as the training cohort (n = 4764) and from Xiangya Hospital (n = 1568) and Zhang's database as validation cohorts. We identified eleven predictors with seven independent risk predictors of sepsis-associated acute kidney injury [fluid input_day1 ≥ 3390 ml (HR hazard ratio 1.42), fluid input_day2 ≥ 2734 ml (HR 1.64), platelet_min_day5 ≤ 224.2 × 109/l (HR 0.86), length of ICU stay ≥ 2.5 days (HR 1.24), length of hospital stay ≥ 5.8 days (HR 1.18), Bun_max_day1 ≥ 20 mmol/l (HR 1.20), and mechanical ventilation time ≥ 96 h (HR 1.11)] by multivariate Cox regression analysis, and the eleven predictors were entered into the nomogram. The nomogram model showed a discriminative ability for estimating sepsis-associated acute kidney injury. These results indicated that clinical parameters such as excess input fluid on the first and second days after admission and longer mechanical ventilation time could increase the risk of developing sepsis-associated acute kidney injury. With our study, we built a real-time prediction model for potentially forecasting acute kidney injury in septic patients that can help clinicians make decisions as early as possible to avoid sepsis-associated acute kidney injury.

Relation of Mechanical Ventilation to Acute Kidney Injury in Myocardial Infarction Patients

INTRODUCTION

Acute kidney injury (AKI) is a common and serious complication in critically ill patients, particularly those with ST-elevation myocardial infarction (STEMI). Mechanical ventilation (MV) is often needed when respiratory deterioration occurs and is continuously associated with higher risk for AKI. Whether MV is an independent predictor for AKI in STEMI patients has not been evaluated before. We aimed to determine a potential association between MV and the occurrence of AKI in STEMI patients.

METHODS

A single-center retrospective cohort in a tertiary referral hospital. We evaluated consecutive patients that were admitted to the cardiac intensive care unit with acute STEMI between 2008 and 2019. Patients were divided into groups based on their need for MV upon admission. To minimize baseline differences between the two groups, propensity matching was performed. The primary outcome was the occurrence of AKI after intubation and secondary outcomes included severe AKI (>2 times the baseline creatinine) and renal recovery.

RESULTS

2,929 patients were included and of them, 143 (5%) were intubated. After using the propensity matching, 138 pairs were available for analysis with similar demographic and clinical characteristics. MV was a predictor for AKI (Table 2, odds ratio [OR]: 3.3, 95% confidence interval [CI]: 1.9-5.6) and severe AKI (OR: 6.3, 95% CI: 2.5-16). These results remained significant after adjusting for the occurrence of a new heart failure and bleeding. Early or partial renal recovery was similar between the groups.

CONCLUSION

MV is independently associated with the occurrence of AKI and severe AKI. The possible mechanism might be temporary, reflected by similar rates of renal recovery.

Extracorporeal Carbon Dioxide Removal: From Pathophysiology to Clinical Applications; Focus on Combined Continuous Renal Replacement Therapy

Lung-protective ventilation (LPV) with low tidal volumes can significantly increase the survival of patients with acute respiratory distress syndrome (ARDS) by limiting ventilator-induced lung injuries. However, one of the main concerns regarding the use of LPV is the risk of developing hypercapnia and respiratory acidosis, which may limit the clinical application of this strategy. This is the reason why different extracorporeal CO₂ removal (ECCO₂R) techniques and devices have been developed. They include low-flow or high-flow systems that may be performed with dedicated platforms or, alternatively, combined with continuous renal replacement therapy (CRRT). ECCO₂R has demonstrated effectiveness in controlling PaCO₂ levels, thus allowing LPV in patients with ARDS from different causes, including those affected by Coronavirus disease 2019 (COVID-19). Similarly, the suitability and safety of combined ECCO₂R and CRRT (ECCO₂R-CRRT), which provides CO₂ removal and kidney support simultaneously, have been reported in both retrospective and prospective studies. However, due to the complexity of ARDS patients and the limitations of current evidence, the actual impact of ECCO₂R on patient outcome still remains to be defined. In this review, we discuss the main principles of ECCO₂R and its clinical application in ARDS patients, in particular looking at clinical experiences of combined ECCO₂R-CRRT treatments.

Predictive role of the neutrophil: lymphocyte ratio in acute kidney injury associated with off-pump coronary artery bypass grafting

OBJECTIVES

This study aims to investigate whether the ratios of cell types in peripheral blood could be used as reliable predictors of off-pump coronary artery bypass grafting (CABG)-associated acute kidney injury (AKI).

MATERIALS AND METHODS

We retrospectively reviewed patients (n = 420) undergoing off-pump CABG from January 1, 2021 to January 1, 2022 in Qilu Hospital of Shandong University. We used logistic regression analysis to identify the potential predictors of off-pump CABG-associated AKI and construct a predictive model. Receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive ability of predictors and prediction models.

RESULTS

The prevalence of AKI associated with off-pump CABG was 20.95%. Patients in the AKI group had significantly higher ratios of peripheral blood cells on postoperative day (POD)1 than patients in the non-AKI group (P < 0.01). The area under the ROC curve (AUC) of the neutrophil:lymphocyte ratio (NLR) on POD1 for predicting off-pump CABG-associated AKI was 0.780 and the cutoff value was 20.07. Patients with high NLR on POD1 had a poor short-term prognosis. The AUC of the predictive model constructed by logistic regression analysis was 0.882. The sensitivity was 68.2% and the specificity was 93.1%.

CONCLUSION

The NLR on POD1 was a reliable predictive biomarker of off-pump CABG-associated AKI. And we successfully construct a prediction model, which contribute to the early recognition and management of off-pump CABG-associated AKI.

Antenatal Steroids and Acute Kidney Injury in Preterm Infants

OBJECTIVE

The aim of this study was to identify the effects of antenatal steroids (ANS) on acute kidney injury (AKI) in very low birth weight (VLBW) preterm infants.

STUDY DESIGN

We performed a retrospective cohort study of VLBW infants admitted to a tertiary-care neonatal intensive care unit between January 2016 and June 2019. Infants were divided into no ANS, partial ANS, and complete ANS groups. Serum creatinine (SCr) levels and rates of AKI during the first 2 weeks of life were compared.

RESULTS

During the study period, 335 infants met our inclusion criteria. Among no, partial, and complete ANS groups, there were significant differences in rates of stages 2 and 3 AKI (17, 11, and 6%, respectively). Logistic regression analysis revealed that complete ANS course was associated with lower rates of AKI (odds ratio [OR] = 0.41 95% confidence interval [CI]: 0.20-0.83) and stages 2 and 3 AKI (OR = 0.205 95% CI: 0.075-0.563) compared with no ANS. Infants in complete ANS group had significantly lower SCr at 72 hours of life and at discharge, SCr peak was compared with infants in no ANS group.

CONCLUSION

In VLBW infants, complete ANS exposure may be associated with improved renal function and decreased risk for AKI compared with no ANS.

KEY POINTS

· The effects of antenatal steroid treatment on renal function in preterm infants are not clear.. · A complete course of antenatal steroid decreases the risk for acute kidney injury in preterm infants.. · Infants who are not exposed to antenatal steroids need closer observation of their renal function..

Causes of Neonatal Acute Renal Injury during Critical Illnesses

The aim of the study was to assess acute kidney injury (AKI) and its contributing risk factors among neonates to reduce morbidity and mortality. The study included 310 neonates who were admitted to the neonatal intensive care unit (NICU). Serum creatinine (SCr) was elevated at admission, after 48 h, and before discharge or death. AKI was defined by either an acute rise in SCr of at least 0.3 mg/dL within 48 h or an increasing or persistently high level of SCr >1.5 mg/dL after 48-72 h of life. The patients who developed AKI were studied regarding the most common risk factors and outcomes. The prevalence of AKI in these neonates was 11.9%. Nephrotoxic drugs were the highest risk factor among patients with AKI, but this was not statistically significant different from patients without AKI. Perinatal asphyxia (59.5%), respiratory distress syndrome (48.6%), shock (43.2%), prematurity (40.5%), and sepsis (37.8%) were the main risk factors of AKI following the nephrotoxic drugs (64.9%). The mortality rate for cases with AKI was 62.1%, with a statistically significant difference from non-AKI neonates. The death rate was higher among neonates born before 36 weeks' gestation. There was no statistical difference between oliguric and non-oliguric neonates with AKI regarding the outcome. The overall incidence of AKI in sick neonates admitted to the NICU was 11.9%. Nephrotoxic drugs, perinatal asphyxia, shock, and prematurity were the main risk factors for developing AKI.

Physiological and Pathophysiological Consequences of Mechanical Ventilation

Mechanical ventilation is a life-support system used to ensure blood gas exchange and to assist the respiratory muscles in ventilating the lung during the acute phase of lung disease or following surgery. Positive-pressure mechanical ventilation differs considerably from normal physiologic breathing. This may lead to several negative physiological consequences, both on the lungs and on peripheral organs. First, hemodynamic changes can affect cardiovascular performance, cerebral perfusion pressure (CPP), and drainage of renal veins. Second, the negative effect of mechanical ventilation (compression stress) on the alveolar-capillary membrane and extracellular matrix may cause local and systemic inflammation, promoting lung and peripheral-organ injury. Third, intra-abdominal hypertension may further impair lung and peripheral-organ function during controlled and assisted ventilation. Mechanical ventilation should be optimized and personalized in each patient according to individual clinical needs. Multiple parameters must be adjusted appropriately to minimize ventilator-induced lung injury (VILI), including: inspiratory stress (the respiratory system inspiratory plateau pressure); dynamic strain (the ratio between tidal volume and the end-expiratory lung volume, or inspiratory capacity); static strain (the end-expiratory lung volume determined by positive end-expiratory pressure [PEEP]); driving pressure (the difference between the respiratory system inspiratory plateau pressure and PEEP); and mechanical power (the amount of mechanical energy imparted as a function of respiratory rate). More recently, patient self-inflicted lung injury (P-SILI) has been proposed as a potential mechanism promoting VILI. In the present chapter, we will discuss the physiological and pathophysiological consequences of mechanical ventilation and how to personalize mechanical ventilation parameters.

Kidney Injury in COVID-19: Epidemiology, Molecular Mechanisms, and Potential Therapeutic Targets

As of December 2021, SARS-CoV-2 had caused over 250 million infections and 5 million deaths worldwide. Furthermore, despite the development of highly effective vaccines, novel variants of SARS-CoV-2 continue to sustain the pandemic, and the search for effective therapies for COVID-19 remains as urgent as ever. Though the primary manifestation of COVID-19 is pneumonia, the disease can affect multiple organs, including the kidneys, with acute kidney injury (AKI) being among the most common extrapulmonary manifestations of severe COVID-19. In this article, we start by reflecting on the epidemiology of kidney disease in COVID-19, which overwhelmingly demonstrates that AKI is common in COVID-19 and is strongly associated with poor outcomes. We also present emerging data showing that COVID-19 may result in long-term renal impairment and delve into the ongoing debate about whether AKI in COVID-19 is mediated by direct viral injury. Next, we focus on the molecular pathogenesis of SARS-CoV-2 infection by both reviewing previously published data and presenting some novel data on the mechanisms of cellular viral entry. Finally, we relate these molecular mechanisms to a series of therapies currently under investigation and propose additional novel therapeutic targets for COVID-19.

Translational insights into mechanisms and preventive strategies after renal injury in neonates

Adverse perinatal circumstances can cause acute kidney injury (AKI) and contribute to chronic kidney disease (CKD). Accumulating evidence indicate that a wide spectrum of perinatal conditions interferes with normal kidney development and ultimately leads to aberrant kidney structure and function later in life. The present review addresses the lack of mechanistic knowledge with regard to perinatal origins of CKD and provides a comprehensive overview of pre- and peri-natal insults, including genetic predisposition, suboptimal nutritional supply, obesity and maternal metabolic disorders as well as placental insufficiency leading to intrauterine growth restriction (IUGR), prematurity, infections, inflammatory processes, and the need for life-saving treatments (e.g. oxygen supplementation, mechanical ventilation, medications) in neonates. Finally, we discuss future preventive, therapeutic, and regenerative directions. In summary, this review highlights the perinatal vulnerability of the kidney and the early origins of increased susceptibility toward AKI and CKD during postnatal life. Promotion of kidney health and prevention of disease require the understanding of perinatal injury in order to optimize perinatal micro- and macro-environments and enable normal kidney development.

Kidney and lung in pathology: mechanisms and clinical implications

There is a close, physiological, relationship between kidney and lung that begin in the fetal age, and is aimed to keep homeostatic balance in the body. From a pathological point of view, the kidneys could be damaged by inflammatory mediators or by immune-mediated factors linked to a primary lung disease or, conversely, it could be the kidney disease that causes lung damage. Non-immunological mechanisms are frequently involved in renal and pulmonary diseases, as observed in chronic conditions. This crosstalk have clinical and therapeutic consequences. This review aims to describe the pulmonary-renal link in physiology and in pathological conditions.

Double arterial cannulation versus right axillary artery cannulation for acute type A aortic dissection: a retrospective study

Background

Cannulation strategy in surgery for acute type A aortic dissection (ATAAD) remains controversial. We aimed to retrospectively analyze the safety and efficacy of double arterial cannulation (DAC) compared with right axillary cannulation (RAC) for ATAAD.

Methods

From January 2016 to December 2018, 431 ATAAD patients were enrolled in the study. Patients were divided into DAC group (n = 341) and RAC group (n = 90). Propensity score matching analysis was performed to compare the early and mid-term outcomes between these two groups. To confirm the organ protection effect by DAC, intraoperative blood gas results and cardiopulmonary bypass parameters were compared between the two groups.

Results

Demographics and preoperative comorbidities were comparable between two groups, while patients in DAC group were younger than RAC group (51.55 ± 13.21 vs. 56.07 ± 12.16 years, P < 0.001). DAC had a higher incidence of limb malperfusion (18.2% vs. 10.0%, P = 0.063) and lower incidence of coronary malperfusion (5.3% vs. 12.2%, P = 0.019). No significant difference in cardiopulmonary bypass and cross-clamp time was found between the two groups. The in-hospital mortality was 13.5% (58/431), while there was no difference between the two groups (13.5% vs. 13.3%; P = 0.969). Patients who underwent DAC had higher incidence of postoperative stroke (5.9% vs. 0%, P = 0.019) and lower incidence of postoperative acute kidney injury (AKI) (24.7% vs. 40.3%; P = 0.015). During a mean follow-up period of 31.8 (interquartile range, 25–45) months, the overall survival was 81.5% for DAC group and 78.0% for RAC group (P = 0.560). Intraoperative blood gas results and cardiopulmonary bypass parameters showed that DAC group had more intraoperative urine output volume than RAC group (P = 0.05), and the time of cooling (P = 0.04) and rewarming (P = 0.04) were shorter in DAC group.

Conclusions

DAC will not increase the surgical risks compared to RAC, but could reduce the incidence of postoperative AKI which may be benefit for renal protection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01714-5.

Mortality and evolution between community and hospital-acquired COVID-AKI

Background

Acute kidney injury (AKI) is associated with poor outcomes in COVID patients. Differences between hospital-acquired (HA-AKI) and community-acquired AKI (CA-AKI) are not well established.

Methods

Prospective, observational cohort study. We included 877 patients hospitalized with COVID diagnosis at two third-level hospitals in Mexico. Primary outcome was all-cause mortality at 28 days compared between COVID patients with CA-AKI and HA-AKI. Secondary outcomes included the need for KRT, and risk factors associated with the development of CA-AKI and HA-AKI.

Results

A total of 377 patients (33.7%) developed AKI. CA-AKI occurred in 202 patients (59.9%) and HA-AKI occurred in 135 (40.1%). Patients with CA-AKI had more significant comorbidities, including diabetes (52.4% vs 38.5%), hypertension (58.4% vs 39.2%), CKD (30.1% vs 14.8%), and COPD (5.9% vs 1.4%), than those with HA-AKI. Patients’ survival without AKI was 87.1%, with CA-AKI it was 75.4%, and with HA-AKI it was 69.6%, log-rank test p < 0.001. Only age > 60 years (OR 1.12, 95% CI 1.06–1.18, p <0.001), COVID severity (OR 1.09, 95% CI 1.03–1.16, p = 0.002), the need in mechanical lung ventilation (OR 1.67, 95% CI 1.56–1.78, p <0.001), and HA-AKI stage 3 (OR 1.16, 95% CI 1.05–1.29, p = 0.003) had a significant increase in mortality. The presence of CKD (OR 1.48, 95% CI 1.391.56, p < 0.001), serum lymphocytes < 1000 μL (OR 1.03, 95% CI 1.00–1.07, p = 0.03), the need in mechanical lung ventilation (OR 1.06, 95% CI 1.02–1.11, p = 0.003), and CA-AKI stage 3 (OR 1.37, 95% CI 1.29–1.46, p < 0.001) were the only variables associated with a KRT start.

Conclusions

We found that COVID patients who are complicated by CA-AKI have more comorbidities and worse biochemical parameters at the time of hospitalization than HA-AKI patients, but despite these differences, their probability of dying is similar.

Outcome-Stratified Analysis of Biomarker Trajectories for Patients Infected With Severe Acute Respiratory Syndrome Coronavirus 2

Longitudinal trajectories of vital signs and biomarkers during admission remain poorly characterized for COVID-19 patients despite their potential to provide critical insights about disease progression. We studied 1884 patients with SARS-CoV2 infection from 3/4/2020-6/25/2020 within one Maryland hospital system and used a retrospective longitudinal framework with linear mixed-effects models to investigate relevant biomarker trajectories leading up to three critical outcomes: mechanical ventilation, discharge, and death. Trajectories of four vital signs (respiratory rate, SpO₂/FiO₂, pulse, and temperature) and four lab values (C-reactive protein (CRP), absolute lymphocyte count (ALC), estimated glomerular filtration rate (eGFR), and D-dimer) clearly distinguished the trajectories of COVID-19 patients. Prior to any ventilation, log-CRP, log-ALC, respiratory rate, and SpO₂/FiO₂ trajectories diverge approximately 8-10 days before discharge or death. Following ventilation, log-CRP, log-ALC, respiratory rate, SpO₂/FiO₂, and eGFR trajectories again diverge 10-20 days prior to death or discharge. Trajectories improved until discharge and remained unchanged or worsened until death. Our approach characterizes the distribution of biomarker trajectories leading up to competing outcomes of discharge versus death. Moving forward, this model can contribute to quantifying the joint probability of future biomarkers and outcomes provided clinical data up to a given moment.

Acute Kidney Injury and Acute Respiratory Distress Syndrome

Acute kidney injury (AKI) complicates approximately a third of all acute respiratory distress syndrome (ARDS) cases, and the combination of the two drastically worsens prognosis. Recent advances in ARDS supportive care have led to improved outcomes; however, much less is known on how to prevent and support patients with AKI and ARDS together. Understanding the dynamic relationship between the kidneys and lungs is crucial for the practicing intensivist to prevent injury. This article summarizes key concepts for the critical care physician managing a patient with ARDS complicated by AKI. Also provided is a discussion of AKI in the COVID-19 era.

Predictors of acute kidney injury in patients with acute decompensated heart failure in emergency departments in China

Objective

This retrospective multicentre observational study was performed to assess the predictors of acute kidney injury (AKI) in patients with acute decompensated heart failure (ADHF) in emergency departments in China.

Methods

In total, 1743 consecutive patients with ADHF were recruited from August 2017 to January 2018. Clinical characteristics and outcomes were compared between patients with and without AKI. Predictors of AKI occurrence and underdiagnosis were assessed in multivariate regression analyses.

Results

Of the 1743 patients, 593 (34.0%) had AKI. AKI was partly associated with short-term all-cause mortality and cost. Cardiovascular comorbidities such as coronary heart disease, diabetes mellitus, and hypertension remained significant predictors of AKI in the univariate analysis. AKI was significantly more likely to occur in patients with a lower arterial pH, lower albumin concentration, higher creatinine concentration, and higher N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration. Patients treated with inotropic agents were significantly more likely to develop AKI during their hospital stay.

Conclusion

This study suggests that cardiovascular comorbidities, arterial pH, the albumin concentration, the creatinine concentration, the NT-proBNP concentration, and use of inotropic agents are predictors of AKI in patients with ADHF.

Possible Predictive Factor of Acute Respiratory Distress Syndrome Development After Mild Traumatic Brain Injury: A Single Rural Trauma Center Preliminary Study

Introduction Acute respiratory distress syndrome (ARDS) after mild traumatic brain injury (TBI) can be associated with significant morbidity and mortality. This study aimed to evaluate the potential predictive factors of ARDS development following mild TBI in trauma patients. Methods A retrospective chart review was done for adult trauma patients with mild TBI (GCS 13-15) requiring admission at our center from 2012 to 2020. Linear regression analysis and chi-square test were utilized to identify independent predictors of the association with ARDS in adults with mild TBI.  Results A total of 784 mild TBI patients were admitted during the time of interest; 34 patients developed ARDS during their index hospitalization. Patients who had ARDS were more likely to have acute kidney injury (AKI; p < 0.0001), sepsis (p < 0.01), rib fractures (p < 0.05), use of anticoagulants (p < 0.001), deep vein thrombosis (p < 0.001), transfusion during the first 4four hours upon admission (p = 0.01), intravenous fluid (IVF) resuscitation during the first four hours (p <0.05), the first eight hours (p = 0.01), the first 12 hours (p = 0.03), and intubation upon the admission (p < 0.0001). ARDS associated with mild TBI demonstrated a statistically significant increase in mortality during the index hospitalization (p < 0.0001). Conclusion ARDS after mild TBI can be associated with significant morbidity and mortality. Key risk factors identified include AKI, sepsis, anticoagulant use, deep vein thrombosis (DVT), transfusion in the first four hours, IVF resuscitation in the first four, eight, and 12 hours, and intubation upon admission.

Community- versus hospital-acquired acute kidney injury in hospitalised COVID-19 patients

Background

Acute kidney injury (AKI) is a recognised complication of coronavirus disease 2019 (COVID-19), yet the reported incidence varies widely and the associated risk factors are poorly understood.

Methods

Data was collected on all adult patients who returned a positive COVID-19 swab while hospitalised at a large UK teaching hospital between 1st March 2020 and 3rd June 2020. Patients were stratified into community- and hospital-acquired AKI based on the timing of AKI onset.

Results

Out of the 448 eligible patients with COVID-19, 118 (26.3 %) recorded an AKI during their admission. Significant independent risk factors for community-acquired AKI were chronic kidney disease (CKD), diabetes, clinical frailty score and admission C-reactive protein (CRP), systolic blood pressure and respiratory rate. Similar risk factors were significant for hospital-acquired AKI including CKD and trough systolic blood pressure, peak heart rate, peak CRP and trough lymphocytes during admission. In addition, invasive mechanical ventilation was the most significant risk factor for hospital-acquired AKI (adjusted odds ratio 9.1, p < 0.0001) while atrial fibrillation conferred a protective effect (adjusted odds ratio 0.29, p < 0.0209). Mortality was significantly higher for patients who had an AKI compared to those who didn’t have an AKI (54.3 % vs. 29.4 % respectively, p < 0.0001). On Cox regression, hospital-acquired AKI was significantly associated with mortality (adjusted hazard ratio 4.64, p < 0.0001) while community-acquired AKI was not.

Conclusions

AKI occurred in over a quarter of our hospitalised COVID-19 patients. Community- and hospital-acquired AKI have many shared risk factors which appear to converge on a pre-renal mechanism of injury. Hospital- but not community acquired AKI was a significant risk factor for death.

Incidence and Outcomes of Acute Kidney Injury in COVID-19: A Systematic Review

BACKGROUND AND OBJECTIVES

The recent worldwide pandemic of COVID-19 has been a serious, multidimensional problem that has left a detrimental worldwide impact on individuals of all ages and several organ systems. The typical manifestation of kidney involvement is acute kidney injury (AKI); however, there is a lack of consensus data regarding AKI epidemiology in COVID-19. This systematic literature review aims to bridge this knowledge gap.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

MEDLINE and Cochrane library were systematically searched for the literature related to AKI in COVID-19 patients of all ages. MedRxIV was searched for relevant unpublished manuscripts. Two reviewers independently assessed the literature on the incidence of AKI and mortality, extracting the need for kidney replacement therapy (KRT).

RESULTS

Sixty studies (n = 43,871 patients) were included in this review. The pooled incidence of AKI among COVID-19 patients was 19.45% (95% confidence intervals [95% CI]: 14.63-24.77%), while the pooled incidence of AKI COVID-19 patients requiring KRT was 39.04% (16.38-64.57%). The pooled proportion of COVID+ patients was significantly lower at 8.83% (5.64% to 12/66%). The overall mortality of COVID-19 patients was calculated to be 17.71% (95% CI: 11.49-24.93%), while the mortality among patients with AKI was higher at 54.24% (95% CI: 44.70-63.63%).

CONCLUSION

This comprehensive systematic review summarizes the available literature pertaining to AKI epidemiology in COVID-19 patients and highlights the incidence, associated mortality, and the need for KRT in this susceptible population.

Acute Kidney Injury in COVID-19: a Brief Review

The contemporary evolution of the coronavirus disease 2019 (COVID-19) outbreak from the Wuhan, China, with a high rate of transmission will act the global medical emergency with immense morbidity and mortality rate across the world. The cell entry of COVID-19 via angiotensin-converting enzyme 2 receptor (ACE-2 receptor) will damage the respiratory system by the cytopathic effect induced by replication of the virus genome in the host and respond respiratory failure with an elevation of cytokine factor-like interleukin (IL) IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha), etc. However, the lung-kidney cross talk will evidence the activation of molecular mechanisms from pro-inflammatory cytokines and concerned with kidney damage, though the elevated rate of ACE-2 receptor in the kidney will enhance the possibility of mortality with consideration of acute kidney injury. This review provides relevant information which suggests the rate of mortality in COVID-19 patient associated with acute kidney injury (AKI) which lacks critical monitoring of kidney function with a clinical consideration of intervention to avoid kidney damage in the initial stage of the disease.

Cardio-pulmonary-renal interactions in ICU patients. Role of mechanical ventilation, venous congestion and perfusion deficit on worsening of renal function: Insights from the MIMIC-III database

Background Mechanical ventilation (MV) in ICU patients may impact hemodynamics and renal function. We aimed to describe the interactions of MV settings, hemodynamic parameters and worsening of renal function (WRF). Methods We included adult patients admitted for the first time in the ICU from the MIMIC-III database. Mean arterial blood pressure (mABP), central venous pressure (CVP) and positive end-expiratory pressure (PEEP) were collected and summarized as a time-weighted mean. The main outcome was WRF defined as acute kidney injury (AKI) occurrence or one-KDIGO stage worsening compared to the KDIGO stage the day before. We used a multinomial logistic regression at day 1 (ldmk-1) and day 2 (ldmk-2) according to a landmark-approach, with a two-days sliding perspective. Results 27,248/61,051 patients met the inclusion criteria (15,258 male (56.0%); 60.1% over 60 y). ICU and hospital mortality were 7.4 and 10.7%, respectively. MV was independently associated with WRF in the ldmrk-1 and -2 models (relative risk ratio [RRR] 8.15 [6.58;10.11] and 7.08 [3.97;12.61] at day-3 and 4, respectively). In MV patients, PEEP was associated with WRF in the ldmrk-1 and -2 models (RRR 1.36 [1.16, 1.6] and 1.17 [0.88, 1.56] by 1 cmH₂O increase at day-3 and 4, respectively). Mean perfusion pressure decreased while central venous pressure increased over PEEP categories. In multivariable analysis, mABP, CVP and PEEP were independently associated with WRF. Conclusion In this large cohort of ICU patients, we observed a strong relationship between MV and WRF. PEEP was associated with WRF in MV patients. This association relied at least partly on renal venous congestion.

Optimizing Pharmacokinetics-Pharmacodynamics of Antimicrobial Management in Patients with Sepsis: A Review

Critically ill patients with sepsis or septic shock are at an increased risk of death. Early and aggressive interventions are essential for improving clinical outcomes. There are a number of therapeutic and practical challenges in the management of antimicrobials in patients with sepsis. These include the timely selection and administration of appropriate antimicrobials, significant physiological alterations that can influence antimicrobial pharmacokinetics, and significant interpatient variability of antimicrobial concentrations using standard dosing approaches. Understanding the impact of these factors on the probability of attaining pharmacokinetic-pharmacodynamic target goals is essential to guide optimal therapy. Using rapid diagnostic technology could facilitate timely selection of antimicrobials, and therapeutic drug monitoring would provide a more individualized dosing approach. Using an interdisciplinary sepsis team would also be beneficial in coordinating efforts to overcome the challenges encountered during this critical period to ensure optimal care.

Two to Tango: Kidney-Lung Interaction in Acute Kidney Injury and Acute Respiratory Distress Syndrome

Acute Kidney Injury (AKI) is an independent risk factor for mortality in hospitalized patients. AKI syndrome leads to fluid overload, electrolyte and acid-base disturbances, immunoparalysis, and propagates multiple organ dysfunction through organ "crosstalk". Preclinical models suggest AKI causes acute lung injury (ALI), and conversely, mechanical ventilation and ALI cause AKI. In the clinical setting, respiratory complications are a key driver of increased mortality in patients with AKI, highlighting the bidirectional relationship. This article highlights the challenging and complex interactions between the lung and kidney in critically ill patients with AKI and acute respiratory distress syndrome (ARDS) and global implications of AKI. We discuss disease-specific molecular mediators and inflammatory pathways involved in organ crosstalk in the AKI-ARDS construct, and highlight the reciprocal hemodynamic effects of elevated pulmonary vascular resistance and central venous pressure (CVP) leading to renal hypoperfusion and pulmonary edema associated with fluid overload and increased right ventricular afterload. Finally, we discuss the notion of different ARDS "phenotypes" and the response to fluid overload, suggesting differential organ crosstalk in specific pathological states. While the directionality of effect remains challenging to distinguish at the bedside due to lag in diagnosis with conventional renal function markers and lack of tangible damage markers, this review provides a paradigm for understanding kidney-lung interactions in the critically ill patient.

Risk factors and long-term outcomes of elderly patients complicating with acute kidney injury after type A acute aortic dissection surgery: a retrospective study

Background

To identify risk factors and long-term outcomes for acute kidney injury (AKI) in elderly patients who underwent type A acute aortic dissection (TA-AAD) emergency surgeries.

Methods

This retrospective study enrolled 214 consecutive patients who underwent TA-AAD emergency surgeries between January 2014 to December 2018 in Nanjing Drum Tower hospital. The diagnosis of AKI was made based on the Kidney Disease: Improving Global Outcomes definition (KDIGO) criteria. Multivariable regression analysis was performed to identify risk factors for postoperative AKI. Kaplan-Meier curves were generated to compare the long-term outcomes between patients with and without AKI complication after TA-AAD surgeries.

Results

Among all enrolled patients, 114 (53.3%) developed AKI during postoperative period. The median age of patients with or without AKI was 68.0 (64.0, 74.0) and 66.0 (62.0, 72.8) years respectively. Renal replacement therapy (RRT) was required in 43 patients (20.1%). The 30-day mortality rate was 21.5% in all enrolled patients with 26.3% in AKI group and 16.0% in non-AKI group (P=0.067) respectively. Longer mechanical ventilation duration was identified as the only independent risk factor for developing AKI by multivariable logistic regression analysis. In addition, our data suggested that the long-term cumulative survival rate was different between two groups.

Conclusions

Postoperative AKI after TA-AAD surgeries was common and associated with worsened long-term mortality in elderly patients. Longer postoperative mechanical ventilation duration was identified as the only independent risk factor for the development of AKI.

Immunopathophysiology of trauma-related acute kidney injury

Physical trauma can affect any individual and is globally accountable for more than one in every ten deaths. Although direct severe kidney trauma is relatively infrequent, extrarenal tissue trauma frequently results in the development of acute kidney injury (AKI). Various causes, including haemorrhagic shock, rhabdomyolysis, use of nephrotoxic drugs and infectious complications, can trigger and exacerbate trauma-related AKI (TRAKI), particularly in the presence of pre-existing or trauma-specific risk factors. Injured, hypoxic and ischaemic tissues expose the organism to damage-associated and pathogen-associated molecular patterns, and oxidative stress, all of which initiate a complex immunopathophysiological response that results in macrocirculatory and microcirculatory disturbances in the kidney, and functional impairment. The simultaneous activation of components of innate immunity, including leukocytes, coagulation factors and complement proteins, drives kidney inflammation, glomerular and tubular damage, and breakdown of the blood-urine barrier. This immune response is also an integral part of the intense post-trauma crosstalk between the kidneys, the nervous system and other organs, which aggravates multi-organ dysfunction. Necessary lifesaving procedures used in trauma management might have ambivalent effects as they stabilize injured tissue and organs while simultaneously exacerbating kidney injury. Consequently, only a small number of pathophysiological and immunomodulatory therapeutic targets for TRAKI prevention have been proposed and evaluated.

Incidence, Risk Factors, and Prognostic Implications of Acute Kidney Injury in Patients with Acute Exacerbation of COPD

Purpose

Little is known about the incidence, risk factors, and prognostic implications of acute kidney injury (AKI) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in China. In this study, we investigated the incidence, risk factors, and short-term outcomes of AKI in these patients.

Patients and Methods

We analyzed the records of 1768 patients admitted to Nanjing First Hospital with a principal diagnosis of AECOPD. Of these, 377 patients had AKI.

Results

AKI occurred in 377 patients (21%). Independent risk factors for AKI in patients with AECOPD were advanced age, coronary artery disease, anemia, cancer, chronic kidney disease, hypercapnic encephalopathy, acute respiratory failure, and mechanical ventilation. Patients with AKI had worse prognostic implications and were more likely to require mechanical ventilation (38.7% vs 19.1%, P<0.001); non-invasive mechanical ventilation (38.2% vs 18.9%, P<0.001); invasive mechanical ventilation (18.3% vs 3.1%, P<0.001); intensive care unit (ICU) admission (33.7% vs 12.9%, P<0.001); had a longer ICU stay (9 days vs 8 days, P=0.033) and longer hospitalization (13 days vs 10 days, P<0.001); and higher in-hospital mortality (18.0% vs 2.7%, P<0.001) than those without AKI. Multivariable analysis indicated that compared to patients without AKI, those with stage 1, 2, or 3 AKI had a 1.9-fold, 2.1-fold, or 6.0-fold increased risk of in-hospital death, respectively.

Conclusion

AKI is common in patients with AECOPD requiring hospitalization. Patients with AKI have worse short-term outcomes. Thus, AKI may be a prognostic predictor of patient survival.

Risk factors and outcomes of acute kidney injury in ventilated newborns

Purpose: This study aimed to investigate the occurrence and risk factors of acute kidney injury (AKI) in ventilated newborns.

Methods: In total, 139 newborns receiving mechanical ventilation (MV) were reviewed in this retrospective study. The demographic and clinical data were collected. Then, the independent risk factors for AKI were evaluated using univariate and multivariate logistic regression analyses.

Results: The incidence rate of AKI was 15.11% (21/139) in ventilated newborns. Univariate analysis showed significant differences in gestational age, birth weight, Apagar scores, the highest oxygen concentration, serum creatinine levels at admission and 48 h after MV, history of asphyxia, urine output at 48 h after MV, invasive MV, noninvasive MV, and outcomes between AKI and non-AKI groups (all p < .05). The lower gestational age (odd ratio (OR): 1.194, 95% confidence interval (CI): 1.013–1.407, p = .035), the increased use of invasive mechanical ventilation (IMV) (OR: 4.790, 95% CI: 1.115–20.575, p = .035), and lower birth weight (OR: 0.377, 95% CI: 0.178–0.801, p = .011) were independent risk factors for the occurrence of AKI. Additionally, higher stage of AKI was significantly associated with poor prognosis of AKI (p = .018).

Conclusion: In this retrospective study, it was found that lower gestational age, birth weight, and increased use of IMV were independent risk factors for AKI in ventilated newborns. The poor prognosis might be indicated by the higher AKI stage.

Distant organ dysfunction in acute kidney injury

Acute kidney injury (AKI) is a common complication in critically ill patients and it is associated with increased morbidity and mortality. Epidemiological and clinical data show that AKI is linked to a wide range of distant organ injuries, with the lungs, heart, liver, and intestines representing the most clinically relevant affected organs. This distant organ injury during AKI predisposes patients to progression to multiple organ dysfunction syndrome and ultimately, death. The strongest direct evidence of distant organ injury occurring in AKI has been obtained from animal models. The identified mechanisms include systemic inflammatory changes, oxidative stress, increases in leucocyte trafficking and the activation of proapoptotic pathways. Understanding the pathways driving AKI-induced distal organ injury are critical for the development and refinement of therapies for the prevention and attenuation of AKI-related morbidity and mortality. The purpose of this review is to summarize both clinical and preclinical studies of AKI and its role in distant organ injury.

A pulmonary source of infection in patients with sepsis-associated acute kidney injury leads to a worse outcome and poor recovery of kidney function

BACKGROUND

Hospital mortality rates are higher among patients with sepsis-associated acute kidney injury (SA-AKI) than among patients with sepsis. However, the pathogenesis underlying SA-AKI remains unclear. We hypothesized that the source of infection affects development of SA-AKI. We aim to explore the relationship between the anatomical source of infection and outcome in patients with SA-AKI.

METHODS

Between January 2013 and January 2018, 113 patients with SA-AKI admitted to our Emergency Center were identified and divided into two groups: those with pulmonary infections and those with other sources of infection. For each patient, we collected data from admission until either discharge or death. We also recorded the clinical outcome after 90 days for the discharged patients.

RESULTS

The most common source of infection was the lung (52/113 cases, 46%), followed by gastrointestinal (GI) (25/113 cases, 22.1%) and urinary (22/113, 19.5%) sources. Our analysis showed that patients with SA-AKI had a significantly worse outcome (30/52 cases, P<0.001) and poorer kidney recovery (P=0.015) with pulmonary sources of infection than those infected by another source. Data also showed that patients not infected by a pulmonary source more likely experienced shock (28/61 cases, P=0.037).

CONCLUSION

This study demonstrated that the source of infection influenced the outcome of SA-AKI patients in an independent manner. Lung injury may influence renal function in an as-yet undetermined manner as the recovery of kidney function was poorer in SA-AKI patients with a pulmonary source of infection.

A prospective study of acute kidney injury in the intensive care unit: development and validation of a risk prediction model

BACKGROUND

Acute kidney injury (AKI) has high morbidity and mortality in intensive care units (ICU). It can also lead to chronic kidney disease (CKD), more costs and longer hospital stay. Early identification of AKI is important.

METHODS

We conducted this monocenter prospective observational study at West China Hospital, Sichuan University, China. We recorded information of each patient in the ICU within 24 h after admission and updated every two days. Patients who reached the primary outcome were accepted into the AKI group. Of all patients, we randomly drew 70% as the development cohort and the remaining 30% as the validation cohort. Using binary logistic regression we got a risk prediction model of the development cohort. In the validation cohort, we validated its discrimination by the area under the receiver operator curve (AUROC) and calibration by a calibration curve.

RESULTS

There were 656 patients in the development cohorts and 280 in the validation cohort. Independent predictors of AKI in the risk prediction model including hypertension, chronic kidney disease, acute pancreatitis, cardiac failure, shock, pH ≤ 7.30, CK > 1000 U/L, hypoproteinemia, nephrotoxin exposure, and male. In the validation cohort, the AUROC is 0.783 (95% CI 0.730-0.836) and the calibration curve shows good calibration of this prediction model. The optimal cut-off value to distinguish high-risk and low-risk patients is 4.5 points (sensitivity is 78.4%, specificity is 73.2% and Youden's index is 0.516).

CONCLUSIONS

This risk prediction model can help to identify high-risk patients of AKI in ICU to prevent the development of AKI and treat it at the early stages. Trial registration TCTR, TCTR20170531001. Registered 30 May 2017, http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=2573.

Human Adipose Tissue-Derived Stromal Cells Attenuate the Multiple Organ Injuries Induced by Sepsis and Mechanical Ventilation in Mice

Mechanical ventilation (MV) can augment sepsis-induced organ injury. Previous studies indicate that human mesenchymal stem cells (hMSCs) have immune-modulatory effect. We hypothesize that human adipose tissue-derived stromal cells (hADSCs) could attenuate MV and sepsis-induced organ injury. Male C57BL/6 mice were randomized to five groups: Sham group; MV group; cecal ligation and puncture (CLP) group; CLP + MV group; and CLP + MV + hADSC group. Anesthetized mice were subjected to cecal ligation and puncture surgery. The mice then received mechanical ventilation (12 ml/kg), with or without the intervention of hADSCs. The survival rate, organ injury of the liver and kidney, total protein and cells in bronchoalveolar lavage fluid (BALF), and histological changes of the lung and liver were examined. The level of IL-6 in BALF was measured by ELISA. Real-time quantitative PCR was used to analyze mRNA of IL-6 and tumor necrosis factor-α (TNF-α). hADSC treatment increased survival rate of septic mice with MV. hADSCs attenuated dysfunction of the liver and kidney and decreased lung inflammation and tissue injury of the liver and lung. IL-6 level in BALF and TNF-α and IL-6 mRNA expression in the tissue of the lung, liver, and kidney were significantly reduced by hADSC treatment. MV with conventional tidal volume aggravates CLP-induced multiple organ injuries. hADSCs inhibited the compound injuries possibly through modulation of immune responses.

Fluid balance in pediatric patients in prone position: a pragmatic study

OBJECTIVE

To verify the association between prone position, increased diuresis, and decreased cumulative fluid balance in critically ill pediatric patients who underwent mechanical ventilation (MV) for pulmonary causes and describe adverse events related to the use of the position.

METHODS

This is a retrospective observational study. Patients aged between 1 month and 12 years who underwent MV for pulmonary causes, between January 2013 and December 2015, were selected and divided between those who were put on prone position (PG) and those who were not (CG) during the hospitalization at the Pediatric Intensive Care Unit (PICU). Data were analyzed longitudinally from D1 to D4.

RESULTS

A total of 77 patients (PG = 37 and CG = 40) were analyzed. The general characteristics of both groups were similar. In the comparison between the groups, there was no increase in diuresis or decrease in cumulative fluid balance in the prone group. In the longitudinal analysis of D1 to D4, we saw that the PG presented higher diuresis (p = 0.034) and a lower cumulative fluid balance (p = 0.001) in D2. Regarding the use of diuretics, there was greater use of furosemide (P <0.001) and spironolactone (P = 0.04) in the PG. There was no increase in adverse events during the use of the prone position.

CONCLUSION

The prone position was not associated with increased diuresis or decreased cumulative fluid balance in critically ill pediatric patients who underwent to MV for pulmonary causes.

Factors associated with acute kidney injury in acute respiratory distress syndrome

Background

Acute kidney injury (AKI) is the most frequent extra-pulmonary organ failure in acute respiratory distress syndrome (ARDS). The objective of this study was to assess the factors associated with the development and severity of AKI in patients with ARDS.

Methods

This is a retrospective cohort study of ARDS patients without acute or chronic kidney disease prior to the onset of ARDS over a 7-year period (2010–2017). AKI and severity of AKI were defined according to the Kidney Disease Improving Global Outcomes 2012 guidelines.

Results

Of the 634 ARDS patients, 357 patients met study criteria. A total of 244 (68.3%) patients developed AKI after ARDS onset: 60 (24.6%) had stage I AKI, 66 (27%) had stage II AKI, and 118 (48.4%) had stage III AKI. The median time of AKI onset for stage I AKI was 2 days (interquartile range, 1.5–5.5) while stage II and III AKI was 4 days. On multivariable analysis, factors associated with development of AKI were age [subdistribution hazard ratio (SHR) 1.01, 95% confidence interval (CI) 1.00–1.02], SOFA score (SHR 1.16, 95%CI 1.12–1.21), a history of diabetes mellitus (DM) (SHR 1.42, 95%CI 1.07–1.89), and arterial pH on day 1 of ARDS (SHR per 0.1 units decrease was 1.18, 95%CI 1.05–1.32). In severity of AKI, stage I AKI was associated with age (SHR 1.03, 95%CI 1.01–1.05) and serum bicarbonate on day 1 of ARDS (SHR 1.07, 95%CI 1.02–1.13). Stage II AKI was associated with age (SHR 1.03, 95%CI 1.01–1.05), serum bicarbonate on day 1 (SHR 1.12, 95%CI 1.06–1.18), SOFA score (SHR 1.19, 95%CI 1.10–1.30), history of heart failure (SHR 3.71, 95%CI 1.63–8.46), and peak airway pressure (SHR 1.04, 95%CI 1.00–1.07). Stage III AKI was associated with a higher BMI (SHR 1.02, 95%CI 1.00–1.03), a history of DM (SHR 1.79, 95%CI 1.18–2.72), SOFA score (SHR 1.29, 95%CI 1.22–1.36), and arterial pH on day 1 (SHR per 0.1 units decrease was 1.25, 95%CI 1.05–1.49).

Conclusions

Age, a higher severity of illness, a history of diabetes, and acidosis were associated with development of AKI in ARDS patients. Severity of AKI was further associated with BMI, history of heart failure, and peak airway pressure.

Electronic supplementary material

The online version of this article (10.1186/s13613-019-0552-5) contains supplementary material, which is available to authorized users.

Increased compensatory kidney workload results in cellular damage in a short time porcine model of mixed acidemia - Is acidemia a 'first hit' in acute kidney injury?

Acute kidney injury (AKI) corrupts the outcome of about 50% of all critically ill patients. We investigated the possible contribution of the pathology acidemia on the development of AKI. Pigs were exposed to acidemia, acidemia plus hypoxemia or a normal acid-base balance in an experimental setup, which included mechanical ventilation and renal replacement therapy to facilitate biotrauma caused by extracorporeal therapies. Interestingly, extensive histomorphological changes like a tubular loss of cell barriers occurred in the kidneys after just 5 hours exposure to acidemia. The additional exposure to hypoxemia aggravated these findings. These ‘early’ microscopic pathologies opposed intra vitam data of kidney function. They did not mirror cellular or systemic patterns of proinflammatory molecules (like TNF-α or IL 18) nor were they detectable by new, sensitive markers of AKI like Neutrophil gelatinase-associated lipocalin. Instead, the data suggest that the increased renal proton excretion during acidemia could be an ‘early’ first hit in the multifactorial pathogenesis of AKI.

Sepsis associated acute kidney injury

Sepsis is defined as organ dysfunction resulting from the host's deleterious response to infection. One of the most common organs affected is the kidneys, resulting in sepsis associated acute kidney injury (SA-AKI) that contributes to the morbidity and mortality of sepsis. A growing body of knowledge has illuminated the clinical risk factors, pathobiology, response to treatment, and elements of renal recovery that have advanced our ability to prevent, detect, and treat SA-AKI. Despite these advances, SA-AKI remains an important concern and clinical burden, and further study is needed to reduce the acute and chronic consequences. This review summarizes the relevant evidence, with a focus on the risk factors, early recognition and diagnosis, treatment, and long term consequences of SA-AKI. In addition to literature pertaining to SA-AKI specifically, pertinent sepsis and acute kidney injury literature relevant to SA-AKI was included.

Lung-Kidney Cross-Talk

Awareness of the multifaceted lung and kidney interactions in the critically ill has increased considerably. Cardiogenic and noncardiogenic pulmonary edema represent two entities of pulmonary edema and differ significantly in terms of alveolar fluid clearance. Acute lung injury describes the breakdown of normal lung architecture with development of a high-permeability noncardiogenic pulmonary edema resulting from an inflammation/oxidant-mediated injury to the alveolar-capillary barrier and downregulation of the epithelial active ion transport system. Acute kidney injury is the most common organ dysfunction in patients with acute respiratory distress syndrome. It may develop as a result of blood gas disturbances that compromise renal blood flow and renal compensatory mechanisms; pulmonary hypertension, which may aggravate renal impairment by causing renal congestion and tissue edema; and mechanical ventilation–induced alterations, including systemic release of mediators, all which promote end-organ cell injury. Acute kidney injury, on the other hand, may initiate and perpetuate lung injury resulting from fluid overload and the systemic release of mediators that promote increased pulmonary vascular permeability, lung inflammation, and apoptosis, and breakdown of the transepithelial electrolyte and water transport, ultimately leading to respiratory failure. It is hoped that an in-depth understanding of the factors influencing lung-kidney interactions will encourage physicians to explore and develop new strategies for the benefit of the patient.

This chapter will:1

Review the pathophysiology of acute lung injury.

2

Summarize the emerging understanding of lung-kidney cross-talk in the critically ill patient.

3

Identify the mechanisms by which acute kidney injury may potentiate acute lung injury.

The aquaporin 5 -1364A/C promoter polymorphism impacts on resolution of acute kidney injury in pneumonia evoked ARDS

Background

Aquaporin 5 (AQP5) expression impacts on cellular water transport, renal function but also on key mechanisms of inflammation and immune cell migration that prevail in sepsis and ARDS. Thus, the functionally relevant AQP5 -1364A/C promoter single nucleotide polymorphism could impact on the development and resolution of acute kidney injury (AKI). Accordingly, we tested the hypothesis that the AQP5 promoter -1364A/C polymorphism is associated with AKI in patients suffering from pneumonia evoked ARDS.

Methods

This prospective study included 136 adult patients of Caucasian ethnicity with bacterially evoked pneumonia resulting in ARDS. Blood sampling was performed within 24 hours of ICU admission and patients were genotyped for the AQP5 promoter -1364A/C single nucleotide polymorphism. The development of an AKI and the cumulative net fluid balance was described over a 30-day observation period and compared between the AA and AC/CC genotypes, and between survivors and non-survivors.

Results

Incidence of an AKI upon admission did not differ in AA (58%) and AC/CC genotype carriers (60%; p = 0.791). However, on day 30, homozygous AA genotypes (57%) showed an increased prevalence of AKI compared to AC/CC genotypes (24%; p = 0.001). Furthermore, the AA genotype proved to be a strong, independent risk factor for predicting AKI persistence (odds-ratio: 3.35; 95%-CI: 1.2–9.0; p = 0.017). While a negative cumulative fluid balance was associated with increased survival (p = 0.001) the AQP5 promoter polymorphism had no impact on net fluid balance (p = 0.96).

Conclusions

In pneumonia evoked ARDS, the AA genotype of the AQP5 promoter polymorphism is associated with a decreased recovery rate from AKI and this is independent of fluid balance. Consequently, the role of AQP5 in influencing AKI likely rests in factors other than fluid balance.

Surfactant protein D attenuates acute lung and kidney injuries in pneumonia-induced sepsis through modulating apoptosis, inflammation and NF-κB signaling

Pneumonia and sepsis are major risk factors for acute kidney injury (AKI). Patients with pneumonia and AKI are at increased risk for morbidity and mortality. Surfactant protein D (SP-D) expressed in lung and kidney plays important roles in innate immunity. However, little is known about the role of organ-specific SP-D in the sepsis. The current study uses wild type (WT), SP-D knockout (KO), and humanized SP-D transgenic (hTG, lung-specific SP-D expression) mice to study organ-specific role of SP-D in pneumonia-induced sepsis. Analyses demonstrated differential lung and kidney injury among three-type mice infected with Pseudomonas aeruginosa. After infection, KO mice showed higher injurious scores in both lung and kidney, and decreased renal function than WT and hTG mice. hTG mice exhibited comparable lung injury but more severe kidney injury compared to WT mice. Increased renal tubular apoptosis, NF-κB activation and proinflammatory cytokines in the kidney of KO mice were found when compared with WT and hTG mice. Furthermore, in vitro primary proximal tubular epithelial cells from KO mice showed more apoptosis with higher level of activated caspase-3 than those from WT mice after LPS treatment. Collectively, SP-D attenuates AKI in the sepsis by modulating renal apoptosis, inflammation and NF-κB signaling.

Complications and Pharmacologic Interventions of Invasive Positive Pressure Ventilation During Critical Illness

Objective: To review the fundamentals of invasive positive pressure ventilation (IPPV) and the common complications and associated pharmacotherapeutic management in order to provide opportunities for pharmacists to improve patient outcomes. Data Sources: A MEDLINE literature search (1950-December 2017) was performed using the key search terms invasive positive pressure ventilation, mechanical ventilation, pharmacist, respiratory failure, ventilator associated organ dysfunction, ventilator associated pneumonia, ventilator bundles, and ventilator liberation. Additional references were identified from a review of literature citations. Study Selection and Data Extraction: All English-language original research and review reports were evaluated. Data Synthesis: IPPV is a common supportive care measure for critically ill patients. While lifesaving, IPPV is associated with significant complications including ventilator-associated pneumonia, sinusitis, organ dysfunction, and hemodynamic alterations. Optimization of pain and sedation management provides an opportunity for pharmacists to directly affect IPPV exposure. A number of pharmacotherapeutic interventions are related directly to prophylaxis against IPPV-associated adverse events or aimed at reduction of duration of IPPV. Conclusions: Enhanced knowledge of the common complications, associated pharmacotherapy, and monitoring strategies facilitate the pharmacist's ability to provide increased pharmacotherapeutic insight in a multidisciplinary intensive care unit setting.

Community-acquired versus hospital-acquired acute kidney injury in patients with acute exacerbation of COPD requiring hospitalization in China

Purpose

Previous studies have described the incidence, risk factors, and outcomes for patients with acute exacerbations of COPD (AECOPD) developing acute kidney injury (AKI). However, little is known about the differences between community-acquired AKI (CA-AKI) and hospital-acquired AKI (HA-AKI) in patients with AECOPD. Thus, in this study, we compared prevalence, risk factors, and outcomes for these patients with CA-AKI and HA-AKI.

Patients and methods

This study was conducted from January 2014 to January 2017, and data from adult inpatients with AECOPD were analyzed retrospectively. A total of 1,768 patients were included, 280 patients were identified with CA-AKI and 97 patients were with HA-AKI.

Results

Prevalence of CA-AKI was 15.8% and that of HA-AKI was 5.5%, giving an overall AKI prevalence of 21.3%. Patients with CA-AKI had a higher prevalence of chronic kidney disease (CKD) and lower prevalence of chronic cor pulmonale than patients with HA-AKI. Risk factors for developing HA-AKI and CA-AKI were similar, such as being elderly, requirement for mechanical ventilation, and a history of coronary artery disease and CKD. Patients with HA-AKI were more likely to have stage 3 AKI and worse short-term outcomes. In comparison with patients with CA-AKI, those with HA-AKI were more likely to require non-invasive mechanical ventilation (31.3% versus 16.8%; P = 0.003) and had a longer duration of mechanical ventilation (11 days versus 8 days; P = 0.020), longer hospitalization (14 days versus 12 days; P = 0.038), and higher inpatient mortality (32.0% versus 13.2%; P < 0.001). Patients with HA-AKI had worse (multivariate-adjusted) inpatient survival than those with CA-AKI (hazard ratio, 1.7 [95% confidence interval, 1.03-2.81; P = 0.038] for the HA-AKI group).

Conclusion

AKI was common in patients with AECOPD requiring hospitalization. CA-AKI was more common than HA-AKI but otherwise demonstrated similar demographics and risk factors. Nevertheless, patients with HA-AKI had worse short-term outcomes.