Impaired balance between neutrophil extracellular trap formation and degradation by DNases in COVID-19 disease

BACKGROUND

Thrombo-inflammation and neutrophil extracellular traps (NETs) are exacerbated in severe cases of COVID-19, potentially contributing to disease exacerbation. However, the mechanisms underpinning this dysregulation remain elusive. We hypothesised that lower DNase activity may be associated with higher NETosis and clinical worsening in patients with COVID-19.

METHODS

Biological samples were obtained from hospitalized patients (15 severe, 37 critical at sampling) and 93 non-severe ambulatory cases. Our aims were to compare NET biomarkers, functional DNase levels, and explore mechanisms driving any imbalance concerning disease severity.

RESULTS

Functional DNase levels were diminished in the most severe patients, paralleling an imbalance between NET markers and DNase activity. DNase1 antigen levels were higher in ambulatory cases but lower in severe patients. DNase1L3 antigen levels remained consistent across subgroups, not rising alongside NET markers. DNASE1 polymorphisms correlated with reduced DNase1 antigen levels. Moreover, a quantitative deficiency in plasmacytoid dendritic cells (pDCs), which primarily express DNase1L3, was observed in critical patients. Analysis of public single-cell RNAseq data revealed reduced DNase1L3 expression in pDCs from severe COVID-19 patient.

CONCLUSION

Severe and critical COVID-19 cases exhibited an imbalance between NET and DNase functional activity and quantity. Early identification of NETosis imbalance could guide targeted therapies against thrombo-inflammation in COVID-19-related sepsis, such as DNase administration, to avert clinical deterioration.

TRIAL REGISTRATION

COVERAGE trial (NCT04356495) and COLCOV19-BX study (NCT04332016).

Impact of dexamethasone in severe COVID-19-induced acute kidney injury: a multicenter cohort study

BACKGROUND

Acute kidney injury (AKI) in intensive care unit (ICU) patients with severe COVID-19 is common (> 50%). A specific inflammatory process has been suggested in the pathogenesis of AKI, which could be improved by dexamethasone (DXM). In a small monocenter study (n = 100 patients), we reported a potential protective effect of DXM on the risk of AKI. This study aimed to investigate the preventive impact of DXM on AKI in a multicenter study of patients with severe COVID-19.

METHODS

We conducted a multicenter study in three French ICUs from March 2020 to August 2021. All patients admitted to ICU for severe COVID-19 were included. Individuals with preexistent AKI or DXM administration before admission to ICU were excluded. While never used during the first wave, DXM was used subsequently at ICU entry, providing two treatment groups. Multivariate Cause-specific Cox models taking into account changes in ICU practices over time, were utilized to determine the association between DXM and occurrence of AKI.

RESULTS

Seven hundred and ninety-eight patients were included. Mean age was 62.6 ± 12.1 years, 402/798 (50%) patients had hypertension, and 46/798 (6%) had previous chronic kidney disease. Median SOFA was 4 [3-6] and 420/798 (53%) required invasive mechanical ventilation. ICU mortality was 208/798 (26%). AKI was present in 598/798 (75%) patients: 266/598 (38%), 163/598 (27%), and 210/598 (35%) had, respectively, AKI KDIGO 1, 2, 3, and 61/598 (10%) patients required renal replacement therapy. Patients receiving DXM had a significantly decreased hazard of AKI occurrence compared to patients without DXM (HR 0.67; 95CI 0.55-0.81). These results were consistent in analyses that (1) excluded patients with DXM administration to AKI onset delay of less than 12 h, (2) incorporating the different 'waves' of the COVID-19 pandemic.

CONCLUSIONS

DXM was associated with a decrease in the risk of AKI in severe COVID-19 patients admitted to ICU. This supports the hypothesis that the inflammatory injury of AKI may be preventable.

Plasma Markers of Neutrophil Extracellular Trap Are Linked to Survival but Not to Pulmonary Embolism in COVID-19-Related ARDS Patients

Introduction

Coronavirus disease 2019 (COVID-19) can cause life-threatening acute respiratory distress syndrome (ARDS). Recent data suggest a role for neutrophil extracellular traps (NETs) in COVID-19-related lung damage partly due to microthrombus formation. Besides, pulmonary embolism (PE) is frequent in severe COVID-19 patients, suggesting that immunothrombosis could also be responsible for increased PE occurrence in these patients. Here, we evaluate whether plasma levels of NET markers measured shorty after admission of hospitalized COVID-19 patients are associated with clinical outcomes in terms of clinical worsening, survival, and PE occurrence.

Patients and Methods

Ninety-six hospitalized COVID-19 patients were included, 50 with ARDS (severe disease) and 46 with moderate disease. We collected plasma early after admission and measured 3 NET markers: total DNA, myeloperoxidase (MPO)–DNA complexes, and citrullinated histone H3. Comparisons between survivors and non-survivors and patients developing PE and those not developing PE were assessed by Mann–Whitney test.

Results

Analysis in the whole population of hospitalized COVID-19 patients revealed increased circulating biomarkers of NETs in patients who will die from COVID-19 and in patients who will subsequently develop PE. Restriction of our analysis in the most severe patients, i.e., the ones who enter the hospital for COVID-19-related ARDS, confirmed the link between NET biomarker levels and survival but not PE occurrence.

Conclusion

Our results strongly reinforce the hypothesis that NETosis is an attractive therapeutic target to prevent COVID-19 progression but that it does not seem to be linked to PE occurrence in patients hospitalized with COVID-19.

Prognostic Impact of Early Recovering Acute Kidney Injury Following Liver Transplantation: A Multicenter Retrospective Study

BACKGROUND

Acute kidney injury (AKI) is a common complication after liver transplantation (LT), but the specific impact of rapidly resolving AKI is not elucidated. This study investigates the factors associated with early recovery from AKI and its association with post-LT outcomes.

METHODS

Retrospective analysis of 441 liver transplant recipients with end-stage liver disease without pretransplant renal impairment. AKI was defined according to Kidney Disease Improving Global Outcomes criteria and early renal recovery by its disappearance within 7 d post-LT.

RESULTS

One hundred forty-six patients (32%) developed a post-LT AKI, of whom 99 (69%) recovered early and 45 (31%) did not. Factors associated with early recovery were Kidney Disease Improving Global Outcomes stage 1 (odds ratio [OR],14.11; 95% confidence interval [CI], 5.59-40.22; P < 0.0001), minimum prothrombin time >50 % (OR, 4.50; 95% CI, 1.67-13.46; P = 0.003) and aspartate aminotransferase peak value <1000 U/L (OR, 4.07; 95% CI, 1.64-10.75; P = 0.002) within 48 h post-LT. Patients with early recovery had a renal prognosis similar to that of patients without AKI with no difference in estimated glomerular filtration rate between day 7 and 1 y. Their relative risk of developing chronic kidney disease was 0.88 (95% CI, 0.55-1.41; P = 0.6) with survival identical to patients without AKI and better than patients without early recovery (P < 0.0001).

CONCLUSIONS

Most patients with post-LT AKI recover early and have a similar renal prognosis and survival to those without post-LT AKI. Factors associated with early renal recovery are related to the stage of AKI, the extent of liver injury, and the early graft function. Patients at risk of not recovering may benefit the most from perioperative protective strategies, particularly those aimed at minimizing the adverse effects of calcineurin inhibitors.

High mean arterial pressure target to improve sepsis-associated acute kidney injury in patients with prior hypertension: a feasibility study

BACKGROUND

The optimal mean arterial pressure (MAP) in cases of septic shock is still a matter of debate in patients with prior hypertension. An MAP between 75 and 85 mmHg can improve glomerular filtration rate (GFR) but its effect on tubular function is unknown. We assessed the effects of high MAP level on glomerular and tubular renal function in two intensive care units of a teaching hospital. Inclusion criteria were patients with a history of chronic hypertension and developing AKI in the first 24 h of septic shock. Data were collected during two 6 h periods of MAP regimen administered consecutively after haemodynamic stabilisation in an order depending on the patient's admission unit: a high-target period (80-85 mmHg) and a low-target period (65-70 mmHg). The primary endpoint was the creatinine clearance (CrCl) calculated from urine and serum samples at the end of each MAP period by the UV/P formula.

RESULTS

26 patients were included. Higher urine output (+0.2 (95%:0, 0.4) mL/kg/h; P = 0.04), urine sodium (+6 (95% CI 0.2, 13) mmol/L; P = 0.04) and lower serum creatinine (- 10 (95% CI - 17, - 3) µmol/L; P = 0.03) were observed during the high-MAP period as compared to the low-MAP period, resulting in a higher CrCl (+25 (95% CI 11, 39) mL/mn; P = 0.002). The urine creatinine, urine-plasma creatinine ratio, urine osmolality, fractional excretion of sodium and urea showed no significant variation. The KDIGO stage at inclusion only interacted with serum creatinine variation and low level of sodium excretion at inclusion did not interact with these results.

CONCLUSIONS

In the early stage of sepsis-associated AKI, a high-MAP target in patients with a history of hypertension was associated with a higher CrCl, but did not affect the kidneys' ability to concentrate urine, which may reflect no effect on tubular function.

Characterization of acute kidney injury in critically ill patients with severe coronavirus disease 2019

BACKGROUND

Coronavirus disease 2019 (COVID-19)-associated acute kidney injury (AKI) frequency, severity and characterization in critically ill patients has not been reported.

METHODS

Single-centre cohort performed from 3 March 2020 to 14 April 2020 in four intensive care units in Bordeaux University Hospital, France. All patients with COVID-19 and pulmonary severity criteria were included. AKI was defined using Kidney Disease: Improving Global Outcomes (KDIGO) criteria. A systematic urinary analysis was performed. The incidence, severity, clinical presentation, biological characterization (transient versus persistent AKI; proteinuria, haematuria and glycosuria) and short-term outcomes were evaluated.

RESULTS

Seventy-one patients were included, with basal serum creatinine (SCr) of 69 ± 21 µmol/L. At admission, AKI was present in 8/71 (11%) patients. Median [interquartile range (IQR)] follow-up was 17 (12-23) days. AKI developed in a total of 57/71 (80%) patients, with 35% Stage 1, 35% Stage 2 and 30% Stage 3 AKI; 10/57 (18%) required renal replacement therapy (RRT). Transient AKI was present in only 4/55 (7%) patients and persistent AKI was observed in 51/55 (93%). Patients with persistent AKI developed a median (IQR) urine protein/creatinine of 82 (54-140) (mg/mmol) with an albuminuria/proteinuria ratio of 0.23 ± 20, indicating predominant tubulointerstitial injury. Only two (4%) patients had glycosuria. At Day 7 after onset of AKI, six (11%) patients remained dependent on RRT, nine (16%) had SCr >200 µmol/L and four (7%) had died. Day 7 and Day 14 renal recovery occurred in 28% and 52%, respectively.

CONCLUSION

Severe COVID-19-associated AKI is frequent, persistent, severe and characterized by an almost exclusive tubulointerstitial injury without glycosuria.

Effect of Hydroxyethyl Starch vs Saline for Volume Replacement Therapy on Death or Postoperative Complications Among High-Risk Patients Undergoing Major Abdominal Surgery: The FLASH Randomized Clinical Trial

IMPORTANCE

It is not known if use of colloid solutions containing hydroxyethyl starch (HES) to correct for intravascular deficits in high-risk surgical patients is either effective or safe.

OBJECTIVE

To evaluate the effect of HES 130/0.4 compared with 0.9% saline for intravascular volume expansion on mortality and postoperative complications after major abdominal surgery.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, double-blind, parallel-group, randomized clinical trial of 775 adult patients at increased risk of postoperative kidney injury undergoing major abdominal surgery at 20 university hospitals in France from February 2016 to July 2018; final follow-up was in October 2018.

INTERVENTIONS

Patients were randomized to receive fluid containing either 6% HES 130/0.4 diluted in 0.9% saline (n = 389) or 0.9% saline alone (n = 386) in 250-mL boluses using an individualized hemodynamic algorithm during surgery and for up to 24 hours on the first postoperative day, defined as ending at 7:59 am the following day.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of death or major postoperative complications at 14 days after surgery. Secondary outcomes included predefined postoperative complications within 14 days after surgery, durations of intensive care unit and hospital stays, and all-cause mortality at postoperative days 28 and 90.

RESULTS

Among 826 patients enrolled (mean age, 68 [SD, 7] years; 91 women [12%]), 775 (94%) completed the trial. The primary outcome occurred in 139 of 389 patients (36%) in the HES group and 125 of 386 patients (32%) in the saline group (difference, 3.3% [95% CI, -3.3% to 10.0%]; relative risk, 1.10 [95% CI, 0.91-1.34]; P = .33). Among 12 prespecified secondary outcomes reported, 11 showed no significant difference, but a statistically significant difference was found in median volume of study fluid administered on day 1: 1250 mL (interquartile range, 750-2000 mL) in the HES group and 1500 mL (interquartile range, 750-2150 mL) in the saline group (median difference, 250 mL [95% CI, 83-417 mL]; P = .006). At 28 days after surgery, 4.1% and 2.3% of patients had died in the HES and saline groups, respectively (difference, 1.8% [95% CI, -0.7% to 4.3%]; relative risk, 1.76 [95% CI, 0.79-3.94]; P = .17).

CONCLUSIONS AND RELEVANCE

Among patients at risk of postoperative kidney injury undergoing major abdominal surgery, use of HES for volume replacement therapy compared with 0.9% saline resulted in no significant difference in a composite outcome of death or major postoperative complications within 14 days after surgery. These findings do not support the use of HES for volume replacement therapy in such patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02502773.

Perioperative antibiotherapy should replace prophylactic antibiotics in patients undergoing pancreaticoduodenectomy preceded by preoperative biliary drainage

BACKGROUND AND OBJECTIVES

Pancreaticoduodenectomy (PD) remains a morbid surgery. Preoperative biliary drainage (PBD) is often necessary before surgery but is associated with biliary contamination. We compared the postoperative complications of patients undergoing PBD who received the usual prophylactic antibiotics (PAs) or systematic antibiotherapy (ABT).

METHODS

All patients who underwent surgery between 2008 and 2017 were included. Systematic perioperative ABT with piperacillin + tazobactam (ABT group) was implemented in 2014 as the standard of care for PBD. Patients treated in the period before such implementation, during which standard cefazolin was given, served as the controls (PAs group). The primary outcomes were postoperative complications.

RESULTS

We included 122 patients with PBD who underwent surgery. There were no demographic differences between the two groups. Perioperative ABT was associated with a reduction in deep abdominal abscesses (36% vs 10%, P = .0008), respiratory tract infections (15% vs 3%; P = .02), bacteremia (41% vs 6%; P < .0001), and a shorter length of hospital stay (17 [13-27] vs 13 [10-14] days; P < .0001). ABT was a protective factor against the development of deep abdominal abscesses (odds ratio [OR] = 0.16; P = .001) whereas smoking (OR = 3.9) and pancreatic fistula (OR = 19.1) were risk factors.

CONCLUSION

Systematic perioperative ABT in patients undergoing PD preceded by PBD may reduce deep surgical infections and the length of hospital stay.

Blood platelets and sepsis pathophysiology: A new therapeutic prospect in critically [corrected] ill patients?

Beyond haemostasis, platelets have emerged as versatile effectors of the immune response. The contribution of platelets in inflammation, tissue integrity and defence against infections has considerably widened the spectrum of their role in health and disease. Here, we propose a narrative review that first describes these new platelet attributes. We then examine their relevance to microcirculatory alterations in multi-organ dysfunction, a major sepsis complication. Rapid progresses that are made on the knowledge of novel platelet functions should improve the understanding of thrombocytopenia, a common condition and a predictor of adverse outcome in sepsis, and may provide potential avenues for management and therapy.

CD40 signaling and hepatic steatosis: Unanticipated links

Obesity predisposes to an increased risk of nonalcoholic fatty liver disease (NAFLD). Hepatic steatosis is the key pathological feature of NAFLD and has emerged as a metabolic disorder in which innate and adaptive arms of the immune response play a central role in disease pathogenesis. Recent studies have revealed unexpected relationships between CD40 signaling and hepatic steatosis in high fat diet rodent models. CD154, the ligand of CD40, is a mediator of inflammation and controls several critical events of innate and adaptive immune responses. In the light of these reports, we discuss potential links between CD40 signaling and hepatic steatosis in NAFLD.

Kinetic eGFR and Novel AKI Biomarkers to Predict Renal Recovery

BACKGROUND AND OBJECTIVES

Prompt recognition of severe renal impairment could improve the early management of critically ill patients. We compared the value of kinetic eGFR, plasma neutrophil gelatinase-associated lipocalin (NGAL), and urine tissue inhibitor of metalloproteinase-2 and urine insulin-like growth factor-binding protein 7 ([TIMP-2]*[IGFBP7]) in predicting short-term recovery from AKI and major adverse kidney events.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

During the 6-month study period, 245 patients were admitted to our intensive care unit. This study included 57 consecutive patients presenting with AKI within the first 24 hours after admission. AKI markers were evaluated at inclusion (day 0) and 24 hours later (day 1). Kinetic eGFR was calculated on day 1 according to serum creatinine evolution. Renal recovery was defined as normalization of serum creatinine with reversal of oliguria within 48 hours. Major adverse kidney events included death, need for RRT, or persistence of renal dysfunction at hospital discharge.

RESULTS

Plasma NGAL and [TIMP-2]*[IGFBP7] predicted renal recovery, with area under the receiver-operating characteristic curve (AUC-ROC) values between 0.70 and 0.79 at inclusion. Although plasma NGAL values frequently reached the maximal measurement range, their decrease on day 1 predicted recovery. The kinetic eGFR calculation after initial resuscitation provided the best AUC-ROC value for renal recovery, at 0.87. The best predictions for major adverse kidney events were provided by [TIMP-2]*[IGFBP7] and kinetic eGFR (equal AUC-ROCs of 0.81). Combining AKI markers in addition to clinical prediction models improved the discrimination and reclassification of patients who will recover from AKI or suffer from major adverse kidney events.

CONCLUSIONS

Biomarkers of kidney damage predicted short-term renal recovery and major adverse kidney events for an unselected cohort of critically ill patients. Calculating the kinetic eGFR imposed a delay after initial resuscitation but provided a good diagnostic and prognostic approach. The utility of functional and damage AKI marker combinations in addition to clinical information requires validation in larger prospective studies.

New frontiers for platelet CD154

The role of platelets extends beyond hemostasis. The pivotal role of platelets in inflammation has shed new light on the natural history of conditions associated with acute or chronic inflammation. Beyond the preservation of vascular integrity, platelets are essential to tissue homeostasis and platelet-derived products are already used in the clinics. Unanticipated was the role of platelets in the adaptative immune response, allowing a renewed conceptual approach of auto-immune diseases. Platelets are also important players in cancer growth and dissemination. Platelets fulfill most of their functions through the expression of still incompletely characterized membrane-bound or soluble mediators. Among them, CD154 holds a peculiar position, as platelets represent a major source of CD154 and as CD154 contributes to most of these new platelet attributes. Here, we provide an overview of some of the new frontiers that the study of platelet CD154 is opening, in inflammation, tissue homeostasis, immune response, hematopoiesis and cancer.

Effect of flumazenil on diaphragm electrical activation during weaning from mechanical ventilation after acute respiratory distress syndrome

BACKGROUND

Diaphragm electrical activation (EAdi) and the ratio of tidal volume to EAdi (VT/EAdi) may provide clinical information on neuroventilatory efficiency (NVE) in patients being weaned from mechanical ventilation. We tested the hypothesis that residual sedation could interfere with respiratory recovery, by assessing the effects of flumazenil on EAdi and VT/EAdi ratio.

METHODS

This observational study included 13 patients breathing with pressure-support ventilation (PSV) after a long period of controlled mechanical ventilation (i.e. >4 days) plus midazolam-based sedation for acute respiratory distress syndrome. EAdi and respiratory patterns were compared before and after a bolus of flumazenil, which was given because neurological status needed to be evaluated.

RESULTS

Flumazenil induced a significant increase in EAdi [+71 (41-123)%, P=0.0002] and VT [+17 (8-32)%, P=0.0005], resulting in significantly decreased NVE [-34 (15-43)%]. The increased VT was significantly correlated with the increased EAdi (ρ=0.70, P=0.009).

CONCLUSIONS

During weaning from mechanical ventilation, the diaphragmatic contribution to the breathing process may be reduced by residual midazolam-induced ventilatory depression. The increased EAdi with reversal of residual sedation was associated with a proportional increase in VT. These findings should be considered by the attending physician when interpreting daily EAdi and VT changes during weaning from mechanical ventilation.

Intraoperative management of heart-lung interactions: "from hypothetical prediction to improved titration"

Extensive literature describes the suitability of dynamic parameters to predict responsiveness in fluid. However, based on heart-lung interactions, these parameters can have serious limitations, including the use of protective lung ventilation. Although the latter seems to be beneficial for healthy patients undergoing high-risk surgery, the intraoperative interpretation of dynamic parameters to predict fluid responsiveness can be hazardous. In this context, the attending physician could, alternatively, titrate the need of fluids with a small fluid challenge, which remains unaffected by low tidal volume, the presence of arrhythmia, or the presence of spontaneous ventilation. When intraoperative prediction of fluid responsiveness is required in mechanically ventilated patients, "improved" titration should be preferred to a hypothetical prediction.

Neuro-ventilatory efficiency during weaning from mechanical ventilation using neurally adjusted ventilatory assist

BACKGROUND

Neuro-ventilatory efficiency (NVE), defined as the tidal volume to electrical diaphragm-activity ratio (VT/EAdi) at the beginning and end of the weaning process after acute hypoxaemic respiratory failure, may provide valuable information about patient recovery.

METHODS

This observational study included 12 patients breathing with neurally adjusted ventilatory assist (NAVA). When a spontaneous breathing trial (SBT) with pressure support of 7 cm H2O and PEEP was unsuccessful, NAVA was used and the level was adjusted to obtain an EAdi of ∼60% of maximal EAdi during SBT. VT and EAdi were recorded continuously. We compared changes in NVE between NAVA and SBT at the first failed and first successful SBT.

RESULTS

When patients were switched from NAVA to SBT, NVE was significantly reduced during both unsuccessful and successful SBT (-56 and -38%, respectively); however, this reduction was significantly lower when SBT was successful (P=0.01). Between the first and last day of weaning, we observed that NVE decreased with NAVA [40.6 (27.7-89.5) vs 28.8 (18.6-46.7); P=0.002] with a significant decrease in NAVA level, whereas it remained unchanged during SBT [15.4 (10.7-39.1) vs 19.5 (11.6-29.6); P=0.50] with significant increases in both EAdi and VT and no difference in respiratory rhythm.

CONCLUSIONS

These results suggest that in patients after respiratory failure and prolonged mechanical ventilation, changes in VT and NVE, between SBTs are indicative of patient recovery. Larger clinical trials are needed to clarify whether changes in NVE reliably predict weaning in patients ventilated with NAVA.

High-volume versus standard-volume haemofiltration for septic shock patients with acute kidney injury (IVOIRE study): a multicentre randomized controlled trial

PURPOSE

Septic shock is a leading cause of death among critically ill patients, in particular when complicated by acute kidney injury (AKI). Small experimental and human clinical studies have suggested that high-volume haemofiltration (HVHF) may improve haemodynamic profile and mortality. We sought to determine the impact of HVHF on 28-day mortality in critically ill patients with septic shock and AKI.

METHODS

This was a prospective, randomized, open, multicentre clinical trial conducted at 18 intensive care units in France, Belgium and the Netherlands. A total of 140 critically ill patients with septic shock and AKI for less than 24 h were enrolled from October 2005 through March 2010. Patients were randomized to either HVHF at 70 mL/kg/h or standard-volume haemofiltration (SVHF) at 35 mL/kg/h, for a 96-h period.

RESULTS

Primary endpoint was 28-day mortality. The trial was stopped prematurely after enrolment of 140 patients because of slow patient accrual and resources no longer being available. A total of 137 patients were analysed (two withdrew consent, one was excluded); 66 patients in the HVHF group and 71 in the SVHF group. Mortality at 28 days was lower than expected but not different between groups (HVHF 37.9 % vs. SVHF 40.8 %, log-rank test p = 0.94). There were no statistically significant differences in any of the secondary endpoints between treatment groups.

CONCLUSIONS

In the IVOIRE trial, there was no evidence that HVHF at 70 mL/kg/h, when compared with contemporary SVHF at 35 mL/kg/h, leads to a reduction of 28-day mortality or contributes to early improvements in haemodynamic profile or organ function. HVHF, as applied in this trial, cannot be recommended for treatment of septic shock complicated by AKI.

Doppler resistive index to reflect regulation of renal vascular tone during sepsis and acute kidney injury

INTRODUCTION

Renal resistive index (RI), determined by Doppler ultrasonography, directly reveals and quantifies modifications in renal vascular resistance. The aim of this study was to evaluate if mean arterial pressure (MAP) is determinant of renal RI in septic, critically ill patients suffering or not from acute kidney injury (AKI).

METHODS

This prospective observational study included 96 patients. AKI was defined according to RIFLE criteria and transient or persistent AKI according to renal recovery within 3 days.

RESULTS

Median renal RIs were 0.72 (0.68-0.75) in patients without AKI and 0.76 (0.72-0.80) in patients with AKI (P = 0.001). RIs were 0.75 (0.72-0.79) in transient AKI and 0.77 (0.70-0.80) in persistent AKI (P = 0.84). RI did not differ in patients given norepinephrine infusion and was not correlated with norepinephrine dose. RI was correlated with MAP (ρ = -0.47; P = 0.002), PaO2/FiO2 ratio (ρ = -0.33; P = 0.04) and age (ρ = 0.35; P = 0.015) only in patients without AKI.

CONCLUSIONS

A poor correlation between renal RI and MAP, age, or PaO2/FiO2 ratio was found in septic and critically ill patients without AKI compared to patients with AKI. These findings suggest that determinants of RI are multiple. Renal circulatory response to sepsis estimated by Doppler ultrasonography cannot reliably be predicted simply from changes in systemic hemodynamics. As many factors influence its value, the interest in a single RI measurement at ICU admission to determine optimal MAP remains uncertain.

[Changes in kaliemia following rapid sequence induction with succinylcholine in critically ill patients]

OBJECTIVE

Evaluate the changes in potassium following rapid sequence induction with succinylcholine in critically ill-patients and determine whether hospital length of stay could influence the succinylcholine-induced hyperkaliemia.

STUDY DESIGN

Prospective and observational study.

PATIENTS AND METHODS

After approval by our local ethical committee, we prospectively included 36 patients admitted from more than 24hours in ICU and who required succinylcholine for rapid tracheal intubation (1mg/kg). Serum potassium was measured before, 5 and 30min after succinylcholine. The incidence of life-threatening hyperkaliemia (≥6.5mmol/L) was noted.

RESULTS

We could observe significant and transient increase in serum potassium (median increase of 0.45 [0.20-0.80] mmol/L at five minutes). A significant relationship was observed between the ICU length of stay and arterial potassium increase (r=0.37, P<0.05). From the ROC curve, a threshold of 12 days had an 86% sensitivity and 69% specificity in discriminating patients in whom the potassium increase was more than 1.5mmol/L.

CONCLUSION

Induction with succinylcholine is followed by significant but transient hyperkaliema. The ICU length of stay before giving succinylcholine could influence significantly the amplitude of potassium increase.

Fractional excretion of urea as a diagnostic index in acute kidney injury in intensive care patients

PURPOSE

Acute kidney injury (AKI) is a dynamic process that evolves from an early reversible condition to an established disease. Value of urine indices in the event of AKI is uncertain in critically ill patients. The aim of this study was to evaluate the performance of fractional excretion of urea (FeU) for differentiating persistent from transient AKI in patients admitted to the intensive care unit.

METHODS

This was an observational study. Forty-seven patients with AKI according to the RIFLE classification were included. Transient AKI was defined as AKI resolved within 3 days after inclusion. Persistent AKI was defined as persistent serum creatinine elevation or oliguria.

RESULTS

Fractional excretion of urea was lower in case of transient, 33% (25-39), than persistent AKI, 47% (36-61) (P = .001). Areas under the receiver operating characteristic curve for FeU in case of transient AKI were better than those for other urinary indexes, 0.78 (95% confidence interval, 0.63-0.92). Optimal cutoff point according to the receiver operating characteristic curve was 40%. In patients treated with diuretics, FeU was the only predictive index of transient AKI. Fractional excretion of urea gradually increased from days 1 to 7 in transient AKI, whereas plasma creatinine decreased.

CONCLUSIONS

Fractional excretion of urea less than 40% was found to be a sensitive and specific index in differentiating transient from persistent AKI in intensive care unit patients especially if diuretics had been administered.

[Diagnosis and management of acute mesenteric ischemia]

The prevalence of significant splanchnic arterial stenoses is increasing, but remains mostly asymptomatic due to abundant collateral circulation. Acute insufficiency of mesenteric arterial blood flow accounts for 60 to 70% of cases of mesenteric ischemia and results mostly from a superior mesenteric embolus. Despite major advances have been achieved in understanding the pathogenic mechanisms of bowel ischemia, its prognosis remains dismal with mortality rates about 60%. The diagnosis of acute mesenteric ischemia depends upon a high clinical suspicion, especially in patients with known risk factors. Rapid diagnosis is essential to prevent intestinal infarction. However, early signs and symptoms of mesenteric ischemia are non specific, and definitive diagnosis often requires radiologic examinations. Early and liberal implementation of angiography has been the major advance over the past 30 years which allowed increasing diagnostic accuracy of acute mesenteric ischemia. CT and MR-based angiographic techniques have emerged as alternatives less invasive and more accurate to analyse splanchnic vessels and evaluate bowel infarction. The goal of treatment of patients with acute mesenteric ischemia is to restore intestinal oxygenation as quickly as possible after initial management that includes rapid hemodynamic monitoring and support. Surgery should not be delayed in patients suspected of having intestinal necrosis.

Daily titration of neurally adjusted ventilatory assist using the diaphragm electrical activity

PURPOSE

To determine the feasibility of daily titration of the neurally adjusted ventilatory assist (NAVA) level in relation to the maximal diaphragmatic electrical activity (EAdi(maxSBT)) measured during a spontaneous breathing trial (SBT) during pressure support ventilation (PSV).

METHODS

The study included 15 consecutive patients in whom mechanical ventilation weaning was initiated with the NAVA mode. EAdi(maxSBT) was determined daily during an SBT using PSV with 7 cmH2O of inspiratory pressure and no positive end-expiratory pressure (PEEP). If the SBT was unsuccessful, NAVA was used and the level was then adjusted to obtain an EAdi of ~60% of the EAdi(maxSBT). Arterial blood gas analyses were performed 20 min after each change in NAVA level.

RESULTS

Three patients were dropped from the study at day 4 because of worsening of their sickness. The median duration of NAVA ventilation was 4.5 days (IQR 3-6.5). From day 1 to extubation, EAdi(maxSBT) and EAdi increased significantly from 16.6 (9.6) to 21.7 (10.3) μV (P = 0.013) and from 10.0 (5.5) to 15.1 (9.2) μV (P = 0.026), respectively. The pressure delivered significantly decreased from 20 (8) to 10 (5) cmH2O (P = 0.003). Conversely, tidal volume, carbon dioxide tension, and pH values remained unchanged during the same period.

CONCLUSION

These results suggest that daily titration of NAVA level with an electrical goal of ~60% EAdi(maxSBT) is feasible and well tolerated. The respiratory mechanics improvement and increase in respiratory drive allowed for a daily reduction of the NAVA level while preserving breathing, oxygenation, and alveolar ventilation until extubation.

[Use of activated recombinant FVII in the control of haemorrhage following trauma]

Uncontrolled haemorrhage is a major cause of death in trauma patients: sometimes inaccessible to surgery and often associated with coagulopathy. We report a case of severe blunt pelvic trauma associated with suicide. The conventional treatments were unsuccessful and embolization was impossible. The patient required massive blood product transfusion. A 100 microg/kg recombinant activated factor VII dose was infused, twice. After administration of the first dose, the blood requirement decreased dramatically. Further work and trials are required to assess the safety profile and dose regimen for this drug.

Evaluation of bioassays versus contaminant concentrations in explaining the macroinvertebrate community structure in the Rhine-Meuse delta, The Netherlands

It is often assumed that bioassays are better descriptors of sediment toxicity than toxicant concentrations and that ecological factors are more important than toxicants in structuring macroinvertebrate communities. In the period 1992 to 1995, data were collected in the enclosed Rhine-Meuse delta, The Netherlands, on macroinvertebrates, sediment toxicity, sediment contaminant concentrations, and ecological factors. The effect of various groups of pollutants (polycyclic aromatic hydrocarbons, trace metals, oil, polychlorinated biphenyls) and of ecological variables on the structure of the macroinvertebrate community were quantified. Ecological factors explained 17.3% of the macroinvertebrate variation, while contaminants explained 13.8%. Another 14.7% was explained by the covariation between ecological variables and contaminants. Polycyclic aromatic hydrocarbons explained a larger part of the variation than trace metals. The contributions of oil and polychlorinated biphenyls were small but significant. Elevated contaminant concentrations were significantly associated with differences in the macroinvertebrate food web structure. The response in bioassays (Vibrio fischeri, Daphnia magna, Chironomus riparius) was susceptible to certain contaminants but also to certain ecological factors. There was a weak correlation between in situ species composition and bioassays; 1.9% of in situ macroinvertebrate variation was explained by the bioassay responses. This seems to contradict the validity of using bioassays for a system-oriented risk assessment. Possible reasons for this discrepancy might be the manipulations of the sediment before the test and a higher pollutant tolerance of the in situ macroinvertebrates. Thus, macroinvertebrate field surveys and laboratory bioassays yield different types of information on ecotoxicological effects, and both are recommended in sediment risk assessment procedures.