Parenteral irons versus transfused red blood cells for treatment of anemia during canine experimental bacterial pneumonia

Intravenous Iron in Patients Hospitalized with Bacterial Infections: Utilization and Outcomes

Introduction

Given the uncertainties related to IV iron therapy and the potential risk of infection, health care providers may hesitate to use this preparation to treat hospitalized patients with bacterial infections, even if clinically indicated. The aim of this study was to examine patterns of prescribing IV iron in patients who were hospitalized and treated for a bacterial infection, and their associated clinical outcomes.

Methods

This retrospective chart review evaluated adult patients who received both IV iron sucrose and antibiotics during the same admission at Maine Medical Center in 2019. Data collected included iron studies, practices for prescribing IV iron, and clinical outcomes. Data were summarized using descriptive statistics.

Results

A total of 197 patients were evaluated. The median duration of antibiotic therapy was 5(4-9) days. Iron and antibiotic administration overlapped in 153(77.7%) patients, with a mean overlap of 2.7(1-7) days. In the 44 patients without overlap, 20(46%) received IV iron before antibiotics. More than half (57%) of infection types involved urinary tract and respiratory systems. Approximately 2% of patients had antibiotic therapy broadened or duration extended, 7% died, and 16% were readmitted within 30 days of discharge.

Discussion

Prior studies evaluating the risk of infection with IV iron published conflicting results. This is the only study that analyzed outcomes in patients receiving IV iron and antibiotics for infection but not undergoing hemodialysis during a hospital admission. Although our findings support that IV iron treatment is safe among patients with concomitant infection and iron deficiency, this finding may not be the case for all clinical subgroups.

Conclusions

This study showed that when patients were administered IV iron in the setting of acute bacterial infection in our facility, most patients did not have negative outcomes.

Large Animal Models for Simulating Physiology of Transfusion of Red Cell Concentrates-A Scoping Review of The Literature

Background and Objectives: Transfusion of red cell concentrates is a key component of medical therapy. To investigate the complex transfusion-associated biochemical and physiological processes as well as potential risks for human recipients, animal models are of particular importance. This scoping review summarizes existing large animal transfusion models for their ability to model the physiology associated with the storage of erythrocyte concentrates. Materials and Methods: The electronic databases PubMed, EMBASE, and Web of Science were systematically searched for original studies providing information on the intravenous application of erythrocyte concentrates in porcine, ovine, and canine animal models. Results: A total of 36 studies were included in the analysis. The majority of porcine studies evaluated hemorrhagic shock conditions. Pig models showed high physiological similarities with regard to red cell physiology during early storage. Ovine and canine studies were found to model typical aspects of human red cell storage at 42 days. Only four studies provided data on 24 h in vivo survival of red cells. Conclusions: While ovine and canine models can mimic typical human erythrocyte storage for up to 42 days, porcine models stand out for reliably simulating double-hit pathologies such as hemorrhagic shock. Large animal models remain an important area of translational research since they have an impact on testing new pharmacological or biophysical interventions to attenuate storage-related adverse effects and allow, in a controlled environment, to study background and interventions in dynamic and severe disease conditions.

The Limits of Acute Anemia

For many years, physicians’ approach to the transfusion of allogeneic red blood cells (RBC) was not individualized. It was accepted that a hemoglobin concentration (Hb) of less than 10 g/dL was a general transfusion threshold and the majority of patients were transfused immediately. In recent years, there has been increasing evidence that even significantly lower hemoglobin concentrations can be survived in the short term without sequelae. This somehow contradicts the observation that moderate or mild anemia is associated with relevant long-term morbidity and mortality. To resolve this apparent contradiction, it must be recognized that we have to avoid acute anemia or treat it by alternative methods. The aim of this article is to describe the physiological limits of acute anemia, match these considerations with clinical realities, and then present “patient blood management” (PBM) as the therapeutic concept that can prevent both anemia and unnecessary transfusion of RBC concentrates in a clinical context, especially in Intensive Care Units (ICU). This treatment concept may prove to be the key to high-quality patient care in the ICU setting in the future.

The Role of Iron in Staphylococcus aureus Infection and Human Disease: A Metal Tug of War at the Host—Microbe Interface

Iron deficiency anemia can be treated with oral or intravenous Fe supplementation. Such supplementation has considerable effects on the human microbiome, and on opportunistic pathogenic micro-organisms. Molecular understanding of the control and regulation of Fe availability at the host-microbe interface is crucial to interpreting the side effects of Fe supplementation. Here, we provide a concise overview of the regulation of Fe by the opportunistic pathogen Staphylococcus aureus. Ferric uptake regulator (Fur) plays a central role in controlling Fe uptake, utilization and storage in order to maintain a required value. The micro-organism has a strong preference for heme iron as an Fe source, which is enabled by the Iron-regulated surface determinant (Isd) system. The strategies it employs to overcome Fe restriction imposed by the host include: hijacking host proteins, replacing metal cofactors, and replacing functions by non-metal dependent enzymes. We propose that integrated omics approaches, which include metalloproteomics, are necessary to provide a comprehensive understanding of the metal tug of war at the host-microbe interface down to the molecular level.

Effect of washing units of canine red blood cells on storage lesions

Background

In humans, washing stored blood products before transfusion reduces storage lesions and incidence of transfusion reactions, but the effectiveness of washing canine blood is unknown.

Objectives

The objective was to determine if manually washing units of stored blood would reduce storage lesions without adversely affecting erythrocytes. We hypothesized that washing stored units would reduce concentrations of storage lesions and cause minimal erythrocyte damage.

Animals

Eight healthy research dogs.

Methods

Repeated measure cohort study. Units of whole blood were stored for 28 days and washed 3 times with 0.9% NaCl. Blood samples were collected before and after storage, after each wash, and after being held at a simulated transfusion temperature. Variables measured included CBC variables, blood gas analysis, erythrocyte morphology, mean corpuscular fragility (MCF), and eicosanoid concentrations. A Friedman's test was used to evaluate changes in variables (P < .05 was considered significant).

Results

After the first wash, compared to values after storage, there was a significant decrease in potassium (4.3 mmol/L [4.0‐4.7] to 1.2 mmol/L [1‐1.6]; P < .0001, median [range]), lactate (1.45 mmol/L [1.07‐1.79] to 0.69 mmol/L [0.39‐0.93]; P = .002), and partial pressure carbon dioxide (102 mm Hg [80.2‐119.2] to 33.7 mm Hg [24.5‐44.5]; P < .0001), and increase in MCV (69.3 fL [65.7‐72.3] to 74 fL [69.6‐79.5]; P = .0003), and MCF (0.444 fL [0.279‐0.527] to 0.491 fL [0.43‐0.616]; P = .0006).

Conclusions and Clinical Importance

A single wash of stored whole blood significantly reduces most extracellular storage lesions, and additional washing might cause hemolysis.

Risk of Infection Associated With Administration of Intravenous Iron: A Systematic Review and Meta-analysis

Importance

Intravenous iron is recommended by many clinical guidelines based largely on its effectiveness in reducing anemia. However, the association with important safety outcomes, such as infection, remains uncertain.

Objective

To examine the risk of infection associated with intravenous iron compared with oral iron or no iron.

Data Sources

Medline, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for randomized clinical trials (RCTs) from 1966 to January 31, 2021. Ongoing trials were sought from ClinicalTrials.gov, CENTRAL, and the World Health Organization International Clinical Trials Search Registry Platform.

Study Selection

Pairs of reviewers identified RCTs that compared intravenous iron with oral iron or no iron across all patient populations, excluding healthy volunteers. Nonrandomized studies published since January 1, 2007, were also included. A total of 312 full-text articles were assessed for eligibility.

Data Extraction and Synthesis

Data extraction and risk of bias assessments were performed according to the Preferred Reporting Items of Systematic Reviews and Meta-analyses (PRISMA) and Cochrane recommendations, and the quality of evidence was assessed using the GRADE (Grades of Recommendation, Assessment, Development, and Evaluation) approach. Two reviewers extracted data independently. A random-effects model was used to synthesize data from RCTs. A narrative synthesis was performed to characterize the reporting of infection.

Main Outcomes and Measures

The primary outcome was risk of infection. Secondary outcomes included mortality, hospital length of stay, and changes in hemoglobin and red blood cell transfusion requirements. Measures of association were reported as risk ratios (RRs) or mean differences.

Results

A total of 154 RCTs (32 920 participants) were included in the main analysis. Intravenous iron was associated with an increased risk of infection when compared with oral iron or no iron (RR, 1.17; 95% CI, 1.04-1.31; I2 = 37%; moderate certainty of evidence). Intravenous iron also was associated with an increase in hemoglobin (mean difference, 0.57 g/dL; 95% CI, 0.50-0.64 g/dL; I2 = 94%) and a reduction in the risk of requiring a red blood cell transfusion (RR, 0.93; 95% CI, 0.76-0.89; I2 = 15%) when compared with oral iron or no iron. There was no evidence of an effect on mortality or hospital length of stay.

Conclusions and Relevance

In this large systematic review and meta-analysis, intravenous iron was associated with an increased risk of infection. Well-designed studies, using standardized definitions of infection, are required to understand the balance between this risk and the potential benefits.

Mechanistic insights into cell-free hemoglobin-induced injury during septic shock

Cell-free hemoglobin (CFH) levels are elevated in septic shock and are higher in nonsurvivors. Whether CFH is only a marker of sepsis severity or is involved in pathogenesis is unknown. This study aimed to investigate whether CFH worsens sepsis-associated injuries and to determine potential mechanisms of harm. Fifty-one, 10-12 kg purpose-bred beagles were randomized to receive Staphylococcus aureus intrapulmonary challenges or saline followed by CFH infusions (oxyhemoglobin >80%) or placebo. Animals received antibiotics and intensive care support for 96 h. CFH significantly increased mean pulmonary arterial pressures and right ventricular afterload in both septic and nonseptic animals, effects that were significantly greater in nonsurvivors. These findings are consistent with CFH-associated nitric oxide (NO) scavenging and were associated with significantly depressed cardiac function, and worsened shock, lactate levels, metabolic acidosis, and multiorgan failure. In septic animals only, CFH administration significantly increased mean alveolar-arterial oxygenation gradients, also to a significantly greater degree in nonsurvivors. CFH-associated iron levels were significantly suppressed in infected animals, suggesting that bacterial iron uptake worsened pneumonia. Notably, cytokine levels were similar in survivors and nonsurvivors and were not predictive of outcome. In the absence and presence of infection, CFH infusions resulted in pulmonary hypertension, cardiogenic shock, and multiorgan failure, likely through NO scavenging. In the presence of infection alone, CFH infusions worsened oxygen exchange and lung injury, presumably by supplying iron that promoted bacterial growth. CFH elevation, a known consequence of clinical septic shock, adversely impacts sepsis outcomes through more than one mechanism, and is a biologically plausible, nonantibiotic, noncytokine target for therapeutic intervention.NEW & NOTEWORTHY Cell-free hemoglobin (CFH) elevations are a known consequence of clinical sepsis. Using a two-by-two factorial design and extensive physiological and biochemical evidence, we found a direct mechanism of injury related to nitric oxide scavenging leading to pulmonary hypertension increasing right heart afterload, depressed cardiac function, worsening circulatory failure, and death, as well as an indirect mechanism related to iron toxicity. These discoveries alter conventional thinking about septic shock pathogenesis and provide novel therapeutic approaches.

RBC Storage Lesion Studies in Humans and Experimental Models of Shock

The finding of toxicity in a meta-analysis of observational clinical studies of transfused longer stored red blood cells (RBC) and ethical issues surrounding aging blood for human studies prompted us to develop an experimental model of RBC transfusion. Transfusing older RBCs during canine pneumonia increased mortality rates. Toxicity was associated with in vivo hemolysis with release of cell-free hemoglobin (CFH) and iron. CFH can scavenge nitric oxide, causing vasoconstriction and endothelial injury. Iron, an essential bacterial nutrient, can worsen infections. This toxicity was seen at commonly transfused blood volumes (2 units) and was altered by the severity of pneumonia. Washing longer-stored RBCs mitigated these detrimental effects, but washing fresh RBCs actually increased them. In contrast to septic shock, transfused longer stored RBCs proved beneficial in hemorrhagic shock by decreasing reperfusion injury. Intravenous iron was equivalent in toxicity to transfusion of longer stored RBCs and both should be avoided during infection. Storage of longer-stored RBCs at 2 °C instead of higher standard temperatures (4-6 °C) minimized the release of CFH and iron. Haptoglobin, a plasma protein that binds CFH and increases its clearance, minimizes the toxic effects of longer-stored RBCs during infection and is a biologically plausible novel approach to treat septic shock.

Ferroportin inhibition attenuates plasma iron, oxidant stress, and renal injury following red blood cell transfusion in guinea pigs

BACKGROUND

Red blood cell (RBC) transfusions result in the sequestration and metabolism of storage-damaged RBCs within the spleen and liver. These events are followed by increased plasma iron concentrations that can contribute to oxidant stress and cellular injury. We hypothesized that administration of a ferroportin inhibitor (FPN-INH) immediately after acute RBC exchange transfusion could attenuate posttransfusion circulatory compartment iron exposure, by retaining iron in spleen and hepatic macrophages.

STUDY DESIGN AND METHODS

Donor guinea pig blood was leukoreduced, and RBCs were preserved at 4°C. Recipient guinea pigs (n = 5/group) were exchange transfused with donor RBCs after refrigerator preservation and dosed intravenously with a small-molecule FPN-INH. Groups included transfusion with vehicle (saline), 5 mg/kg or 25 mg/kg FPN-INH. A time course of RBC morphology, plasma non-transferrin-bound iron (NTBI) and plasma hemoglobin (Hb) were evaluated. End-study spleen, liver, and kidney organ iron levels, as well as renal tissue oxidation and injury, were measured acutely (24-hr after transfusion).

RESULTS

RBC transfusion increased plasma NTBI, with maximal concentrations occurring 8 hours after transfusion. Posttransfusion iron accumulation resulted in tubule oxidation and acute kidney injury. FPN inhibition increased spleen and liver parenchymal/macrophage iron accumulation, but attenuated plasma NTBI, and subsequent renal tissue oxidation/injury.

CONCLUSION

In situations of acute RBC transfusion, minimizing circulatory NTBI exposure by FPN inhibition may attenuate organ-specific adverse consequences of iron exposure.

When might transferrin, hemopexin or haptoglobin administration be of benefit following the transfusion of red blood cells?

PURPOSE OF REVIEW

After transfusion, a percentage of red blood cells undergo hemolysis within macrophages. Intravascular exposures to hemin and hemoglobin (Hb) can occur after storage bag hemolysis, some transfusion reactions, during use of medical assist devices and in response to bacterial hemolysins. Proteins that regulate iron, hemin and Hb either become saturated after iron excess (transferrin, Tf) or depleted after hemin (hemopexin, Hpx) and Hb (haptoglobin, Hp) excess. Protein saturation or stoichiometric imbalance created by transfusion increases exposure to non-Tf bound iron, hemin and Hb. Tf, Hpx and Hp are being developed for hematological disorders where iron, hemin and Hb contribute to pathophysiology. However, complexed to their ligands, each represents a potential iron source for pathogens, which may complicate the use of these proteins.

RECENT FINDINGS

Erythrophagocytosis by macrophages and processes of cell death that lead to reactive iron exposure are increasingly described. In addition, the effects of transfusion introduced circulatory hemin and Hb are described in the literature, particularly following large volume transfusion, infection and during concomitant medical device use.

SUMMARY

Supplementation with Tf, Hpx and Hp suggests therapeutic potential in conditions of extravascular/intravascular hemolysis. However, their administration following transfusion may require careful assessment of concomitant disease.

INtravenous Iron to Treat Anaemia following CriTical care (INTACT): A protocol for a feasibility randomised controlled trial

Background

Anaemia is common in patients who survive critical illness and is associated with high levels of fatigue and poor quality of life. In non-critically ill patients, treating anaemia with intravenous iron has resulted in meaningful improvements in quality of life, but uncertainties regarding the benefits, risks, timing and optimal route of iron therapy in survivors of critical illness remain.

Methods / Design

INtravenous Iron to Treat Anaemia following CriTical care (INTACT) is an open-label, feasibility, parallel group, randomised controlled trial with 1:1 randomisation to either intravenous iron (1000 mg ferric carboxymaltose) or usual medical care. The primary objective is to assess the feasibility of a future, multicentre randomised controlled trial. Participants will be followed up for up to 90 days post-randomisation. The primary outcome measures, which will be used to determine feasibility, are recruitment and randomisation rates, protocol adherence and completeness of follow-up. Secondary outcome measures include collecting clinical, laboratory, health-related quality of life and safety data to inform the power calculations of a future definitive trial.

Conclusion

Improving recovery from critical illness is a recognised research priority. Whether or not correcting anaemia, with intravenous iron, improves health-related quality of life and recovery requires further investigation. If so, it has the potential to become a rapidly translatable intervention. Prior to embarking on a phase III multicentre trial, a carefully designed and implemented feasibility trial is essential.

Risk of infection associated with intravenous iron preparations: protocol for updating a systematic review

INTRODUCTION

The benefits and risk of intravenous iron have been documented in previous systematic reviews and continue to be the subject of randomised controlled trials (RCTs). An ongoing issue that continues to be raised is the relationship between administering iron and developing infection. This is supported by biological plausibility from animal models. We propose an update of a previously published systematic review and meta-analysis with the primary focus being infection.

METHODS AND ANALYSIS

We will include RCTs and non-randomised studies (NRS) in this review update. We will search the relevant electronic databases. Two reviewers will independently extract data. Risk of bias for RCTs and NRS will be assessed using the relevant tools recommended by The Cochrane Collaboration. Data extracted from RCTs and NRS will be analysed and reported separately. Pooled data from RCTs will be analysed using a random effects model. We will also conduct subgroup analyses to identify any patient populations that may be at increased risk of developing infection. We will provide a narrative synthesis on the definitions, sources and responsible pathogens for infection in the included studies. Overall quality of evidence on the safety outcomes of mortality and infection will be assessed using the Grading of Recommendations, Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

This systematic review will only investigate published studies and therefore ethical approval is not required. The results will be broadly distributed through conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

PROSPERO (CRD42018096023).

Impact of different standard red blood cell storage temperatures on human and canine RBC hemolysis and chromium survival

BACKGROUND

Storage temperature is a critical factor for maintaining red-blood cell (RBC) viability, especially during prolonged cold storage. The target range of 1 to 6°C was established decades ago and may no longer be optimal for current blood-banking practices.

STUDY DESIGN AND METHODS

Human and canine RBCs were collected under standard conditions and stored in precision-controlled refrigerators at 2°C, 4°C, or 6°C.

RESULTS

During 42-day storage, human and canine RBCs showed progressive increases in supernatant non-transferrin-bound iron, cell-free hemoglobin, base deficit, and lactate levels that were overall greater at 6°C and 4°C than at 2°C. Animals transfused with 7-day-old RBCs had similar plasma cell-free hemoglobin and non-transferrin-bound iron levels at 1 to 72 hours for all three temperature conditions by chromium-51 recovery analysis. However, animals transfused with 35-day-old RBCs stored at higher temperatures developed plasma elevations in non-transferrin-bound iron and cell-free hemoglobin at 24 and 72 hours. Despite apparent impaired 35-day storage at 4°C and 6°C compared to 2°C, posttransfusion chromium-51 recovery at 24 hours was superior at higher temperatures. This finding was confounded by a preparation artifact related to an interaction between temperature and storage duration that leads to removal of fragile cells with repeated washing of the radiolabeled RBC test sample and renders the test sample unrepresentative of the stored unit.

CONCLUSIONS

RBCs stored at the lower bounds of the temperature range are less metabolically active and produce less anaerobic acidosis and hemolysis, leading to a more suitable transfusion product. The higher refrigeration temperatures are not optimal during extended RBC storage and may confound chromium viability studies.

What is the effect of perioperative intravenous iron therapy in patients undergoing non-elective surgery? A systematic review with meta-analysis and trial sequential analysis

Background

Guidelines to treat anaemia with intravenous (IV) iron have focused on elective surgical patients with little attention paid to those undergoing non-elective/emergency surgery. Whilst these patients may experience poor outcomes because of their presenting illness, observational data suggests that untreated anaemia may also be a contributing factor to poor outcomes. We conducted a systematic review to investigate the safety and efficacy of IV iron in patients undergoing non-elective surgery.

Methods

We followed a pre-defined review protocol and included randomised controlled trials (RCTs) in patients undergoing non-elective surgery who received IV iron. Primary outcomes were all-cause infection and mean difference in haemoglobin (Hb) at follow-up. Secondary outcomes included transfusion requirements, hospital length of stay (LOS), health-related quality of life (HRQoL), mortality and adverse events.

Results

Three RCTs (605 participants) were included in this systematic review of which two, in both hip fracture (HF) patients, provided data for meta-analysis. Both of these RCTs were at low risk of bias. We found no evidence of a difference in the risk of infection (RR 0.99, 95% CI 0.55 to 1.80, I ² = 9%) or in the Hb concentration at 'short-term' (≤ 7 days) follow-up (mean difference - 0.32 g/L, 95% CI - 3.28 to 2.64, I ² = 37%). IV iron did not reduce the risk of requiring a blood transfusion (RR 0.90, 95% CI 0.73 to 1.11, p = 0.46, I ² = 0%), and we observed no difference in mortality, LOS or adverse events. One RCT reported on HRQoL and found no difference between treatment arms.

Conclusion

We found no conclusive evidence of an effect of IV iron on clinically important outcomes in patients undergoing non-elective surgery. Further adequately powered trials to evaluate its benefit in emergency surgical specialties with a high burden of anaemia are warranted.

Trial registration

This systematic review was registered on PROSPERO (CRD42018096288).

Safety and efficacy of iron therapy on reducing red blood cell transfusion requirements and treating anaemia in critically ill adults: A systematic review with meta-analysis and trial sequential analysis

PURPOSE

To evaluate the safety (risk of infection) and efficacy (transfusion requirements, changes in haemoglobin (Hb)) of iron therapy in adult intensive care unit (ICU) patients.

MATERIALS AND METHODS

We systematically searched seven databases for all relevant studies until January 2018 and included randomized (RCT) studies comparing iron, by any route, with placebo/no iron.

RESULTS

805 participants from 6 RCTs were included. Iron therapy, by any route, did not decrease the risk of requirement for a red blood cell (RBC) transfusion (Risk ratio (RR) 0.91, 95% CI 0.80 to 1.04, p = 0.15) or mean number of RBCs transfused per participant (mean difference (MD) -0.30, 95% CI -0.68 to 0.07, p = 0.15). Iron therapy did increase mean Hb concentration (MD 0.31 g/dL, 95% CI 0.04 to 0.59, p = 0.03). There was no difference in infection (RR 0.95, 95% CI 0.79 to 1.19, p = 0.44). Trial Sequential Analysis suggests that the required participant numbers to detect or reject a clinically important effect of iron therapy on transfusion requirements or infection in ICU patients has not yet been reached.

CONCLUSION

Iron therapy results in a modest increase in Hb. The current evidence is inadequate to exclude an important effect on transfusion requirements or infection.

Haptoglobin improves shock, lung injury, and survival in canine pneumonia

During the last half-century, numerous antiinflammatory agents were tested in dozens of clinical trials and have proven ineffective for treating septic shock. The observation in multiple studies that cell-free hemoglobin (CFH) levels are elevated during clinical sepsis and that the degree of increase correlates with higher mortality suggests an alternative approach. Human haptoglobin binds CFH with high affinity and, therefore, can potentially reduce iron availability and oxidative activity. CFH levels are elevated over approximately 24-48 hours in our antibiotic-treated canine model of S. aureus pneumonia that simulates the cardiovascular abnormalities of human septic shock. In this 96-hour model, resuscitative treatments, mechanical ventilation, sedation, and continuous care are translatable to management in human intensive care units. We found, in this S. aureus pneumonia model inducing septic shock, that commercial human haptoglobin concentrate infusions over 48-hours bind canine CFH, increase CFH clearance, and lower circulating iron. Over the 96-hour study, this treatment was associated with an improved metabolic profile (pH, lactate), less lung injury, reversal of shock, and increased survival. Haptoglobin binding compartmentalized CFH to the intravascular space. This observation, in combination with increasing CFHs clearance, reduced available iron as a potential source of bacterial nutrition while decreasing the ability for CFH and iron to cause extravascular oxidative tissue injury. In contrast, haptoglobin therapy had no measurable antiinflammatory effect on elevations in proinflammatory C-reactive protein and cytokine levels. Haptoglobin therapy enhances normal host defense mechanisms in contrast to previously studied antiinflammatory sepsis therapies, making it a biologically plausible novel approach to treat septic shock.