Anemia in the ICU: anemia of chronic disease versus anemia of acute illness

Iron Metabolism in the Recovery Phase of Critical Illness with a Focus on Sepsis

Iron is an essential nutrient for humans and microbes, such as bacteria. Iron deficiency commonly occurs in critically ill patients, but supplementary iron therapy is not considered during the acute phase of critical illness since it increases iron availability for invading microbes and oxidative stress. However, persistent iron deficiency in the recovery phase is harmful and has potential adverse outcomes such as cognitive dysfunction, fatigue, and cardiopulmonary dysfunction. Therefore, it is important to treat iron deficiency quickly and efficiently. This article reviews current knowledge about iron-related biomarkers in critical illness with a focus on patients with sepsis, and provides possible criteria to guide decision-making for iron supplementation in the recovery phase of those patients.

Relationship between the magnitude of haemoglobin changes and long-term mortality in patients with sepsis: a retrospective cohort study

BACKGROUND

Sepsis is a common and severe disease with a high mortality rate in intensive care unit (ICU). The hemoglobin (HGB) level is a key parameter for oxygen supply in sepsis. Although HGB is associated with the progression of inflammation in sepsis patients, its role as a marker following sepsis treatment remains unclear. Here, we studied the correlation between early temporal changes in HGB levels and long-term mortality rates in septic patients.

METHOD

In this retrospective study of data on patients with sepsis from the Medical Information Mart for Intensive Care (MIMIC) IV database, the outcome was long-term mortality. Patients were divided based on the cut-off of the HGB percentage for receiver operating characteristic (ROC) curve calculation. Kaplan-Meier (KM) survival curves and Cox proportional hazards regression models were used to analyse the associations between groups and outcomes. Propensity score matching (PSM) was used to verify the results.

RESULTS

In this study, 2042 patients with sepsis and changes in HGB levels at day 4 after admission compared to day 1 were enrolled and divided into two groups: group 1 (n = 1147) for those with reduction of HGB < 7% and group 2 (n = 895) for those with dropping ≥ 7%. The long-term survival chances of sepsis with less than a 7% reduction in the proportion of HGB at day four were significantly higher than those of patients in the group with a reduction of 7% or more. After adjusting for covariates in the Cox model, the hazard ratios (HRs) with 95% confidence intervals (CIs) for long-term all-cause mortality in the group with a reduction of 7% or more were as follows: 180 days [HR = 1.41, 95% CI (1.22 to 1.63), P < 0.001]; 360 days [HR = 1.37, 95% CI (1.21 to 1.56), P < 0.001]; 540 days [HR = 1.35, 95% CI (1.20 to 1.53), P < 0.001]; 720 days [HR = 1.45, 95% CI (1.29 to 1.64), P < 0.001]. Additionally, the long-term survival rates, using Kaplan-Meier analysis, for the group with a reduction of 7% or more were lower compared to the group with less than 7% reduction at 180 days (54.3% vs. 65.3%, P < 0.001), 360 days (42.3% vs. 50.9%, P < 0.001), 540 days (40.2% vs. 48.6%, P < 0.001), and 720 days (35.5% vs. 46.1%, P < 0.001). The same trend was obtained after using PSM.

CONCLUSION

A ≥ 7% decrease in HGB levels on Day 4 after admission was associated with worse long-term prognosis in sepsis patients admitted to the ICU.

Guidance for assessment of the inflammation etiologic criterion for the GLIM diagnosis of malnutrition: A modified Delphi approach

BACKGROUND & AIMS

The Global Leadership Initiative on Malnutrition (GLIM) approach to malnutrition diagnosis is based on assessment of three phenotypic (weight loss, low body mass index, and reduced skeletal muscle mass) and two etiologic (reduced food intake/assimilation and disease burden/inflammation) criteria, with diagnosis confirmed by fulfillment of any combination of at least one phenotypic and at least one etiologic criterion. The original GLIM description provided limited guidance regarding assessment of inflammation and this has been a factor impeding further implementation of the GLIM criteria. We now seek to provide practical guidance for assessment of inflammation in support of the etiologic criterion for inflammation.

METHODS

A GLIM-constituted working group with 36 participants developed consensus-based guidance through a modified-Delphi review. A multi-round review and revision process served to develop seven guidance statements.

RESULTS

The final round of review was highly favorable with 99 % overall "agree" or "strongly agree" responses. The presence of acute or chronic disease, infection or injury that is usually associated with inflammatory activity may be used to fulfill the GLIM disease burden/inflammation criterion, without the need for laboratory confirmation. However, we recommend that recognition of underlying medical conditions commonly associated with inflammation be supported by C-reactive protein (CRP) measurements when the contribution of inflammatory components is uncertain. Interpretation of CRP requires that consideration be given to the method, reference values, and units (mg/dL or mg/L) for the clinical laboratory that is being used.

CONCLUSION

Confirmation of inflammation should be guided by clinical judgement based upon underlying diagnosis or condition, clinical signs, or CRP.

Anti-inflammatory therapies are associated with delayed onset of anemia and reduction in transfusion requirements in critically ill patients: results from two studies

BACKGROUND

Anemia is a hallmark of critical illness, which is largely inflammatory driven. We hypothesized that the use of anti-inflammatory agents limits the development of anemia and reduces the need for red blood cell (RBC) transfusions in patients with a hyper-inflammatory condition due to COVID-19.

METHODS

An observational cohort (n = 772) and a validation cohort (a subset of REMAP-CAP, n = 119) of critically ill patients with hypoxemic respiratory failure due to COVID-19 were analyzed, who either received no treatment, received steroids or received steroids plus IL-6 blocking agents. The trajectory of hemoglobin (Hb) decline and the need for RBC transfusions were compared using descriptive statistics as well as multivariate modeling.

RESULTS

In both cohorts, Hb level was higher in the treated groups compared to the untreated group at all time points. In the observational cohort, incidence and number of transfused patients were lower in the group receiving the combination treatment compared to the untreated groups. In a multivariate analysis controlling for baseline Hb imbalance and mechanical ventilation, receipt of steroids remained associated with a slower decline in Hb level and the combination treatment remained associated with a slower decline of Hb and with less transfusions. Results remained the same in the validation cohort.

CONCLUSION

Immunomodulatory treatment was associated with a slower decline in Hb level in critically ill patients with COVID-19 and with less transfusion. Findings point toward inflammation as an important cause for the occurrence of anemia in the critically ill.

Guidance for assessment of the inflammation etiologic criterion for the GLIM diagnosis of malnutrition: A modified Delphi approach

BACKGROUND

The Global Leadership Initiative on Malnutrition (GLIM) approach to malnutrition diagnosis is based on assessment of three phenotypic (weight loss, low body mass index, and reduced skeletal muscle mass) and two etiologic (reduced food intake/assimilation and disease burden/inflammation) criteria, with diagnosis confirmed by fulfillment of any combination of at least one phenotypic and at least one etiologic criterion. The original GLIM description provided limited guidance regarding assessment of inflammation, and this has been a factor impeding further implementation of the GLIM criteria. We now seek to provide practical guidance for assessment of inflammation.

METHODS

A GLIM-constituted working group with 36 participants developed consensus-based guidance through a modified Delphi review. A multiround review and revision process served to develop seven guidance statements.

RESULTS

The final round of review was highly favorable, with 99% overall "agree" or "strongly agree" responses. The presence of acute or chronic disease, infection, or injury that is usually associated with inflammatory activity may be used to fulfill the GLIM disease burden/inflammation criterion, without the need for laboratory confirmation. However, we recommend that recognition of underlying medical conditions commonly associated with inflammation be supported by C-reactive protein (CRP) measurements when the contribution of inflammatory components is uncertain. Interpretation of CRP requires that consideration be given to the method, reference values, and units (milligrams per deciliter or milligram per liter) for the clinical laboratory that is being used.

CONCLUSION

Confirmation of inflammation should be guided by clinical judgment based on underlying diagnosis or condition, clinical signs, or CRP.

Iron as an emerging therapeutic target in critically ill patients

The multiple roles of iron in the body have been known for decades, particularly its involvement in iron overload diseases such as hemochromatosis. More recently, compelling evidence has emerged regarding the critical role of non-transferrin bound iron (NTBI), also known as catalytic iron, in the care of critically ill patients in intensive care units (ICUs). These trace amounts of iron constitute a small percentage of the serum iron, yet they are heavily implicated in the exacerbation of diseases, primarily by catalyzing the formation of reactive oxygen species, which promote oxidative stress. Additionally, catalytic iron activates macrophages and facilitates the growth of pathogens. This review aims to shed light on this underappreciated phenomenon and explore the various common sources of NTBI in ICU patients, which lead to transient iron dysregulation during acute phases of disease. Iron serves as the linchpin of a vicious cycle in many ICU pathologies that are often multifactorial. The clinical evidence showing its detrimental impact on patient outcomes will be outlined in the major ICU pathologies. Finally, different therapeutic strategies will be reviewed, including the targeting of proteins involved in iron metabolism, conventional chelation therapy, and the combination of renal replacement therapy with chelation therapy.

Determinants of the success in flap reconstruction-Outcome analysis of 120 flaps in 484 procedures for pressure injury

Pressure injury (PI) mainly occurs in bedridden older adults or those with physical limitations. Here, we aimed to determine the appropriate timing to conduct flap reconstruction in patients with PIs and identify factors affecting surgical outcomes. We retrospectively reviewed the data of all patients who received debridement or flap reconstruction surgery for PIs in our hospital from January 2016 to December 2021. The extracted data included patient demographics, surgical records, blood test results, vital signs, and flap outcomes. In total, 484 surgical procedures (364 debridements and 120 flaps) were performed on 216 patients. Serum albumin level of ≥2.5 g/dL remarkably increased the likelihood of complete wound healing (odds ratio [OR] = 4.12, P = .032) and reduced the risk of postoperative complications (OR = 0.26, P = .040). In contrast, advanced age (OR = 1.04, P = .045) and serum creatinine level ≥2 mg/dL (OR = 5.07, P = .016) increased the risk of postoperative complications. Thus, patients with a favourable nutrition status have a higher likelihood of achieving complete wound healing. By contrast, patients who are older and have serum creatinine ≥2 mg/dL and serum albumin <2.5 g/dL tend to develop more postoperative complications. Overall, thorough correction for patient inflammation, infection, anaemia, and malnutrition status can provide optimal flap surgery outcomes.

The role of iron in chronic inflammatory diseases: from mechanisms to treatment options in anemia of inflammation

Anemia of inflammation (AI) is a highly prevalent comorbidity in patients affected by chronic inflammatory disorders, such as chronic kidney disease, inflammatory bowel disease, or cancer, that negatively affect disease outcome and quality of life. The pathophysiology of AI is multifactorial, with inflammatory hypoferremia and iron-restricted erythropoiesis playing a major role in the context of disease-specific factors. Here, we review the recent progress in our understanding of the molecular mechanisms contributing to iron dysregulation in AI, the impact of hypoferremia and anemia on the course of the underlying disease, and (novel) therapeutic strategies applied to treat AI.

Zinc protoporphyrin levels in COVID-19 are indicative of iron deficiency and potential predictor of disease severity

Background

Coronavirus disease (COVID-19) has a severe impact on all aspects of patient care. Among the numerous biomarkers of potential validity for diagnostic and clinical management of COVID-19 are biomarkers at the interface of iron metabolism and inflammation.

Methods

The follow-up study included 54 hospitalized patients with laboratory-confirmed COVID-19 with a moderate and severe/critical form of the disease. Iron deficiency specific biomarkers such as iron, ferritin, transferrin receptor, hepcidin, and zinc protoporphyrin (ZnPP) as well as relevant markers of inflammation were evaluated twice: in the first five days when the patient was admitted to the hospital and during five to 15 days; and their validity to diagnose iron deficiency was further assessed. The regression and Receiver Operating Characteristics (ROC) analyses were performed to evaluate the prognosis and determine the probability for predicting the severity of the disease in the first five days of COVID-19.

Results

Based on hemoglobin values, anemia was observed in 21 of 54 patients. Of all iron deficiency anemia-related markers, only ZnPP was significantly elevated (P<0.001) in the anemic group. When patients were grouped according to the severity of disease, slight differences in hemoglobin or other anemia-related parameters could be observed. However, the levels of ZnPP were significantly increased in the severely ill group of patients. The ratio of ZnPP to lymphocyte count (ZnPP/L) had a discrimination power stronger than the neutrophil to lymphocyte count ratio (N/L) to determine disease severity. Additionally, only two markers were independently associated with the severity of COVID-19 in logistic regression analysis; D-dimer (OR (5.606)(95% CI 1.019–30.867)) and ZnPP/L ratio (OR (74.313) (95% CI 1.081–5108.103)).

Conclusions

For the first time ZnPP in COVID-19 patients were reported in this study. Among all iron-related markers tested, ZnPP was the only one that was associated with anemia as based on hemoglobin. The increase in ZnPP might indicate that the underlying cause of anemia in COVID-19 patients is not only due to the inflammation but also of nutritional origin. Additionally, the ZnPP/L ratio might be a valid prognostic marker for the severity of COVID-19.

Association of red blood cell and platelet transfusions with persistent inflammation, immunosuppression, and catabolism syndrome in critically ill patients

The objective of this single-center retrospective cohort study was to investigate the relationship between blood transfusion and persistent inflammation, immunosuppression, and catabolism syndrome (PIICS). The study was conducted at the Critical Care Center at Toho University Omori Medical Center, Japan. We included 391 patients in the PIICS group (hospitalization for > 15 days, C-reactive protein > 3.0 mg/dL or albumin < 3.0 mg/dL or lymph < 800/μL on day 14) and 762 patients in the non-PIICS group (hospitalization for > 15 days and not meeting the PIICS criteria). We performed univariate and multivariate logistic regression analyses using PIICS as the objective variable and red blood cell (RBC) or fresh frozen plasma or platelet (PLT) transfusion and other confounding factors as explanatory variables. In addition, we conducted a sensitivity analysis using propensity score matching analysis. The multivariate and propensity score analyses showed that RBC and PLT transfusions were significantly associated with PIICS. This is the first study to report an association between RBC and PLT transfusions and PIICS. Our findings have contributed to better understanding the risk factors of PIICS and suggest that physicians should consider the risk of PIICS occurrence when administering blood transfusions in intensive care unit (ICU) patients.

A descriptive study on multisystem inflammatory syndrome in children in a single center in West Michigan

BACKGROUND

Multisystem Inflammatory Syndrome in Children (MIS-C) is a rare hyperinflammatory condition that occurs following SARS-CoV-2 infection. There is a paucity of research describing risk factors, optimal management, and outcomes of this life-threatening condition.

METHODS

This is a case series of 26 patients diagnosed with MIS-C in a West Michigan pediatric tertiary care center from April 2020 to February 2021. We describe the clinical, imaging, and laboratory characteristics of these patients and detail their treatments and outcomes with comparisons between Pediatric Intensive Care Unit (PICU) and non-PICU patients. Categorical testing utilized Chi-square and Fisher's Exact tests. Comparison between groups used T-tests or Kruskal-Wallis.

RESULTS

Fifteen patients (57%) required intensive care. There was no statistically significant difference in demographics between PICU and non-PICU patients, however all Black patients required intensive care. Gastrointestinal symptoms were present in 22 patients (84%). Seventeen patients (65%) had Kawasaki-like features and 12 (46%) developed coronary artery dilation. Patients requiring intensive care were less likely to have a reported history of COVID-19 disease or exposure (p = 0.0362). Statistically significant differences were also noted in peak ferritin (p = 0.0075), procalcitonin, and BNP in those who required intensive care.

CONCLUSIONS

Although overlap exists with other hyperinflammatory conditions, our study provides further evidence that MIS-C is a distinct, albeit heterogenous, disorder with various degrees of cardiac involvement. Anakinra, in conjunction with steroid use, appears to be effective and safe in the treatment of MIS-C. This report identifies procalcitonin, peak ferritin, and BNP as potentially useful biomarkers for severity of disease.

Iron, Copper, and Zinc Homeostasis: Physiology, Physiopathology, and Nanomediated Applications

Understanding of how the human organism functions has preoccupied researchers in medicine for a very long time. While most of the mechanisms are well understood and detailed thoroughly, medicine has yet much to discover. Iron (Fe), Copper (Cu), and Zinc (Zn) are elements on which organisms, ranging from simple bacteria all the way to complex ones such as mammals, rely on these divalent ions. Compounded by the continuously evolving biotechnologies, these ions are still relevant today. This review article aims at recapping the mechanisms involved in Fe, Cu, and Zn homeostasis. By applying the knowledge and expanding on future research areas, this article aims to shine new light of existing illness. Thanks to the expanding field of nanotechnology, genetic disorders such as hemochromatosis and thalassemia can be managed today. Nanoparticles (NPs) improve delivery of ions and confer targeting capabilities, with the potential for use in treatment and diagnosis. Iron deficiency, cancer, and sepsis are persisting major issues. While targeted delivery using Fe NPs can be used as food fortifiers, chemotherapeutic agents against cancer cells and microbes have been developed using both Fe and Cu NPs. A fast and accurate means of diagnosis is a major impacting factor on outcome of patients, especially when critically ill. Good quality imaging and bed side diagnostic tools are possible using NPs, which may positively impact outcome.

ICU survivorship: What PAs need to know

ABSTRACT

The number of people surviving critical illnesses is larger than ever. Many of these patients will rely on physician assistants (PAs) to facilitate their care after discharge from the ICU. As a result, PAs must be able to recognize and treat the numerous short- and long-term challenges this vulnerable population faces, especially given the recent surge of critically ill patients resulting from the COVID-19 pandemic.

Prognostic relevance of normocytic anemia in elderly patients affected by cardiovascular disease

BACKGROUND

Anemia associated with cardiovascular diseases (CVD) is a common condition in older persons. Prevalence and prognostic role of anemia were extensively studied in patients with myocardial infarction (MI) or congestive heart failure (CHF) whereas limited data were available on patients with atrial fibrillation (AF). This study was conducted to assess the clinical prevalence and prognostic relevance of anemia in elderly patients affected by AF and other CVDs.

METHODS

A total of 866 elderly patients (430 men and 436 women, age: 65-98 years, mean age: 85 ± 10 years) were enrolled. Among these patients, 267 patients had acute non-ST-segment elevation MI (NSTEMI), 176 patients had acute CHF, 194 patients had acute AF and 229 patients were aged-matched healthy persons (CTR). All parameters were measured at the hospital admission and cardiovascular mortality was assessed during twenty-four months of follow-up.

RESULTS

The prevalence of anemia was higher in NSTEMI, CHF and AF patients compared to CTR subjects (50% vs. 15%, P < 0.05), with normocytic anemia being the most prevalent type (90%). Adjusted mortality risk was higher in anemic patient versus non-anemic patient in all the groups of patients [NSTEMI: hazard ratio (HR) = 1.81, 95% CI: 1.06-2.13; CHF: HR = 2.49, 95% CI: 1.31-4.75; AF: HR = 1.98, 95% CI: 1.01-3.88]. Decreased hemoglobin levels ( P = 0.001) and high reticulocyte index (P = 0.023) were associated with higher mortality in CVD patients.

CONCLUSIONS

The significant associations between CVD and anemia and the prognostic relevance of anemia for elderly patients with CVD were confirmed in this study. The presence of anemia in AF patients is associated with a two-fold increased mortality risk compared with non-anemic AF patients. Low hemoglobin and high reticulocyte count independently predict mortality in elderly patients with CVD.

Six degrees head-down tilt bed rest caused low-grade hemolysis: a prospective randomized clinical trial

This study aimed to measure hemolysis before, during and after 60 days of the ground-based spaceflight analog bed rest and the effect of a nutritional intervention through a prospective randomized clinical trial. Twenty male participants were hospitalized for 88 days comprised of 14 days of ambulatory baseline, 60 days of 6° head-down tilt bed rest and 14 days of reambulation. Ten participants each received a control diet or daily polyphenol associated with omega-3, vitamin E, and selenium supplements. The primary outcome was endogenous carbon monoxide (CO) elimination measured by gas chromatography. Hemolysis was also measured with serial bilirubin, iron, transferrin saturation blood levels and serial 3-day stool collections were used to measure urobilinoid excretion using photometry. Total hemoglobin mass (tHb) was measured using CO-rebreathing. CO elimination increased after 5, 11, 30, and 57 days of bed rest: +289 ppb (95% CI 101-477 ppb; p = 0.004), +253 ppb (78-427 ppb; p = 0.007), +193 ppb (89-298 ppb; p = 0.001) and +858 ppb (670-1046 ppb; p < 0.000), respectively, compared to baseline. Bilirubin increased after 20 and 49 days of bed rest +0.8 mg/l (p = 0.013) and +1.1 mg/l (p = 0.012), respectively; and iron increased after 20 days of bed rest +10.5 µg/dl (p = 0.032). The nutritional intervention did not change CO elimination. THb was lower after 60 days of bed rest -0.9 g/kg (p = 0.001). Bed rest enhanced hemolysis as measured through all three by-products of heme oxygenase. Ongoing enhanced hemolysis over 60 days contributed to a 10% decrease in tHb mass. Modulation of red blood cell control towards increased hemolysis may be an important mechanism causing anemia in astronauts.

Stress Erythropoiesis is a Key Inflammatory Response

Bone marrow medullary erythropoiesis is primarily homeostatic. It produces new erythrocytes at a constant rate, which is balanced by the turnover of senescent erythrocytes by macrophages in the spleen. Despite the enormous capacity of the bone marrow to produce erythrocytes, there are times when it is unable to keep pace with erythroid demand. At these times stress erythropoiesis predominates. Stress erythropoiesis generates a large bolus of new erythrocytes to maintain homeostasis until steady state erythropoiesis can resume. In this review, we outline the mechanistic differences between stress erythropoiesis and steady state erythropoiesis and show that their responses to inflammation are complementary. We propose a new hypothesis that stress erythropoiesis is induced by inflammation and plays a key role in maintaining erythroid homeostasis during inflammatory responses.

Potential of Parameters of Iron Metabolism for the Diagnosis of Anemia of Inflammation in the Critically Ill

BACKGROUND

Anemia of inflammation (AI) is the most common cause of anemia in the critically ill, but its diagnosis is a challenge. New therapies specific to AI are in development, and they require accurate detection of AI. This study explores the potential of parameters of iron metabolism for the diagnosis of AI during an ICU stay.

METHODS

In a nested case-control study, 30 patients developing AI were matched to 60 controls. The iron parameters were determined in plasma samples during an ICU stay. Receiver operating characteristic curves were used to determine the iron parameter threshold with the highest sensitivity and specificity to predict AI. Likelihood ratios as well as positive and negative predictive values were calculated as well.

RESULTS

The sensitivity of iron parameters for diagnosing AI ranges between 62 and 76%, and the specificity between 57 and 72%. Iron and transferrin show the greatest area under the curve. Iron shows the highest sensitivity, and transferrin and transferrin saturation display the highest specificity. Hepcidin and ferritin show the lowest specificity. At an actual anemia prevalence of 53%, the diagnostic accuracy of iron, transferrin, and transferrin saturation was fair, with a positive predictive value between 71 and 73%. Combining iron, transferrin, transferrin saturation, hepcidin, and/or ferritin levels did not increase the accuracy of the AI diagnosis.

CONCLUSIONS

In this explorative study on the use of different parameters of iron metabolism for diagnosing AI during an ICU stay, low levels of commonly measured markers such as plasma iron, transferrin, and transferrin saturation have the highest sensitivity and specificity and outperform ferritin and hepcidin.

Inflammation induces stress erythropoiesis through heme-dependent activation of SPI-C

Inflammation alters bone marrow hematopoiesis to favor the production of innate immune effector cells at the expense of lymphoid cells and erythrocytes. Furthermore, proinflammatory cytokines inhibit steady-state erythropoiesis, which leads to the development of anemia in diseases with chronic inflammation. Acute anemia or hypoxic stress induces stress erythropoiesis, which generates a wave of new erythrocytes to maintain erythroid homeostasis until steady-state erythropoiesis can resume. Although hypoxia-dependent signaling is a key component of stress erythropoiesis, we found that inflammation also induced stress erythropoiesis in the absence of hypoxia. Using a mouse model of sterile inflammation, we demonstrated that signaling through Toll-like receptors (TLRs) paradoxically increased the phagocytosis of erythrocytes (erythrophagocytosis) by macrophages in the spleen, which enabled expression of the heme-responsive gene encoding the transcription factor SPI-C. Increased amounts of SPI-C coupled with TLR signaling promoted the expression of Gdf15 and Bmp4, both of which encode ligands that initiate the expansion of stress erythroid progenitors (SEPs) in the spleen. Furthermore, despite their inhibition of steady-state erythropoiesis in the bone marrow, the proinflammatory cytokines TNF-α and IL-1β promoted the expansion and differentiation of SEPs in the spleen. These data suggest that inflammatory signals induce stress erythropoiesis to maintain erythroid homeostasis when inflammation inhibits steady-state erythropoiesis.

Development of a model for anemia of inflammation that is relevant to critical care

BACKGROUND

Anemia of inflammation (AI) is common in critically ill patients. Although this syndrome negatively impacts the outcome of critical illness, understanding of its pathophysiology is limited. Also, new therapies that increase iron availability for erythropoiesis during AI are upcoming. A model of AI induced by bacterial infections that are relevant for the critically ill is currently not available. This paper describes the development of an animal model for AI that is relevant for critical care research.

RESULTS

In experiments with rats, the rats were inoculated either repeatedly or with a slow release of Streptococcus pneumoniae or Pseudomonas aeruginosa. Rats became ill, but their hemoglobin levels remained stable. The use of a higher dose of bacteria resulted in a lethal model. Then, we turned to a model with longer disease duration, using pigs that were supported by mechanical ventilation after inoculation with P. aeruginosa. The pigs became septic 12 to 24 h after inoculation, with a statistically significant decrease in mean arterial pressure and base excess, while heart rate tended to increase. Pigs needed resuscitation and vasopressor therapy to maintain a mean arterial pressure > 60 mmHg. After 72 h, the pigs developed anemia (baseline 9.9 g/dl vs. 72 h, 7.6 g/dl, p = 0.01), characterized by statistically significant decreased iron levels, decreased transferrin saturation, and increased ferritin. Hepcidin levels tended to increase and transferrin levels tended to decrease.

CONCLUSIONS

Using pathogens commonly involved in pulmonary sepsis, AI could not be induced in rats. Conversely, in pigs, P. aeruginosa induced pulmonary sepsis with concomitant AI. This AI model can be applied to study the pathophysiology of AI in the critically ill and to investigate the effectivity and toxicity of new therapies that aim to increase iron availability.

Inflammatory anemia-associated parameters are related to 28-day mortality in patients with sepsis admitted to the ICU: a preliminary observational study

Background

Anemia is one of the most common complications of sepsis. Sepsis-related anemia is associated mainly with inflammation. We aimed to observe the changes in the inflammatory anemia-associated parameters of patients with sepsis in the early stage of intensive care unit (ICU) admission and to evaluate their association with 28-day mortality.

Methods

A total of 198 patients with sepsis were divided into survivor (n = 110) and non-survivor (n = 88) groups on the basis of 28-day survival. Healthy volunteers (n = 20) were enrolled as a control group. Plasma levels of iron, ferritin, erythropoietin (EPO), soluble transferrin receptor (sTfR), hepcidin, interleukin-6 (IL-6), hemoglobin and the red blood cell distribution width (RDW) were measured on days 1, 3 and 7 of ICU admission. Clinical data and laboratory findings were collected, and the Sequential Organ Failure Assessment (SOFA) score was calculated.

Results

Patients with sepsis showed significant decreases in hemoglobin, plasma iron and sTfR/log ferritin and significant increases in plasma EPO, sTfR, hepcidin, ferritin and IL-6 on days 1, 3 and 7 of ICU admission compared with healthy volunteers. Hemoglobin was correlated negatively with plasma IL-6 and hepcidin. In patients with sepsis, non-survivors had significantly lower plasma iron, EPO and sTfR/log ferritin, but higher plasma hepcidin, ferritin and IL-6 than survivors on days 1, 3 and 7 of ICU admission. Plasma EPO, hepcidin, ferritin, IL-6, sTfR/log ferritin, the RDW and SOFA score were associated significantly with 28-day mortality but to a varying extent. In particular, in predicting 28-day mortality, plasma hepcidin had an area under the receiver operating curve of 0.808 and 87.3% specificity, which was the highest among the inflammatory anemia-associated parameters tested.

Conclusions

Inflammatory anemia-associated parameters changed significantly in patients with sepsis in the first week of ICU admission. Plasma EPO, hepcidin, ferritin, IL-6, sTfR/log ferritin, the RDW and SOFA score were associated significantly with 28-day mortality. Plasma hepcidin might have a superior predictive value, with high specificity, compared with other inflammatory anemia-associated parameters for 28-day mortality of sepsis patients in the ICU.

Electronic supplementary material

The online version of this article (10.1186/s13613-019-0542-7) contains supplementary material, which is available to authorized users.

The effect of red blood cell transfusion on iron metabolism in critically ill patients

BACKGROUND

Anemia of inflammation (AI) has a high prevalence in critically ill patients. In AI, iron metabolism is altered, as high levels of inflammation-induced hepcidin reduce the amount of iron available for erythropoiesis. AI is treated with red blood cell (RBC) transfusions. The effect of RBC transfusion on iron metabolism during inflammatory processes in adults is unknown. We investigated the effect of RBC transfusion on iron metabolism in critically ill patients.

METHODS

In a prospective cohort study in 61 critically ill patients who received 1 RBC unit, levels of iron variables were determined before, directly after, and 24 hours after transfusion in septic and nonseptic patients.

RESULTS

Serum iron levels were low and increased after transfusion (p = 0.02). However, RBC transfusion had no effect on transferrin saturation (p = 0.14) and ferritin levels (p = 0.74). Hepcidin levels increased after RBC transfusion (p = 0.01), while interleukin-6 levels decreased (p = 0.03). In septic patients, RBC transfusion induced a decrease in haptoglobin levels compared to baseline, which did not occur in nonseptic patients (p = 0.01). The effect of RBC transfusion on other iron variables did not differ between septic and nonseptic patients.

CONCLUSION

Transfusion of a RBC unit transiently increases serum iron levels in intensive care unit patients. The increase in hepcidin levels after transfusion can further decrease iron release from intracellular storage making it available for erythropoiesis. RBC transfusion is associated with a decrease in haptoglobin levels in septic compared to nonseptic patients, but did not affect other markers of hemolysis.

Iron metabolism in critically ill patients developing anemia of inflammation: a case control study

BACKGROUND

Anemia occurring as a result of inflammatory processes (anemia of inflammation, AI) has a high prevalence in critically ill patients. Knowledge on changes in iron metabolism during the course of AI is limited, hampering the development of strategies to counteract AI. This case control study aimed to investigate iron metabolism during the development of AI in critically ill patients.

METHODS

Iron metabolism in 30 patients who developed AI during ICU stay was compared with 30 septic patients with a high Hb and 30 non-septic patients with a high Hb. Patients were matched on age and sex. Longitudinally collected plasma samples were analyzed for levels of parameters of iron metabolism. A linear mixed model was used to assess the predictive values of the parameters.

RESULTS

In patients with AI, levels of iron, transferrin and transferrin saturation showed an early decrease compared to controls with a high Hb, already prior to the development of anemia. Ferritin, hepcidin and IL-6 levels were increased in AI compared to controls. During AI development, erythroferrone decreased. Differences in iron metabolism between groups were not influenced by APACHE IV score.

CONCLUSIONS

The results show that in critically ill patients with AI, iron metabolism is already altered prior to the development of anemia. Levels of iron regulators in AI differ from septic controls with a high Hb, irrespective of disease severity. AI is characterized by high levels of hepcidin, ferritin and IL-6 and low levels of iron, transferrin and erythroferrone.

Blood Product Administration in the Critical Care and Perioperative Settings

The critical care and perioperative settings are high consumers of blood products, with multiple units and different products often given to an individual patient. The recommendation of this review is always to consider the risks and benefits for a specific blood product for a specific patient in a specific clinical setting. Optimize patient status by treating anemia and preventing the need for red blood cell transfusion. Consider other options for correction of anemia and coagulation disorders and use an imperative non-overtransfusion policy for all blood products.

Blood Transfusions in Dogs and Cats Receiving Hemodialysis: 230 Cases (June 1997-September 2012)

Background

Multiple factors exist that contribute to anemia in dogs and cats receiving hemodialysis, can necessitate transfusion.

Objectives

To describe blood product usage in dogs and cats with acute and chronic kidney disease that were treated with intermittent hemodialysis to determine risk factors associated with the requirement for blood product transfusion.

Animals

83 cats and 147 dogs undergoing renal replacement therapy at the Animal Medical Center for acute or chronic kidney disease.

Methods

Retrospective medical record review of all dogs and cats receiving renal replacement therapy for kidney disease, from June 1997 through September 2012.

Results

Blood products (whole blood, packed RBCs, or stromal‐free hemoglobin) were administered to 87% of cats and 32% of dogs. The number of dialysis treatments was associated with the requirement for transfusion in cats (adjusted OR 2.21, 95% CI 1.13, 4.32), but not in dogs (adjusted OR 0.98, 95% CI 0.95, 1.03). Administration of a blood product was associated with a higher likelihood of death in dogs (OR 3.198, 95% CI 1.352, 7.565; P = .0098), but not in cats (OR 1.527, 95% CI 0.5404, 4.317, P = .2).

Conclusions and Clinical Importance

Veterinary hospitals with a hemodialysis unit should have reliable and rapid access to safe blood products in order to meet the needs of dogs and cats receiving dialysis.

Anemia management after acute brain injury

Anemia is frequent among brain-injured patients, where it has been associated with an increased risk of poor outcome. The pathophysiology of anemia in this patient population remains multifactorial; moreover, whether anemia merely reflects a higher severity of the underlying disease or is a significant determinant of the neurological recovery of such patients remains unclear. Interestingly, the effects of red blood cell transfusions (RBCT) in moderately anemic patients remain controversial; although hemoglobin levels are increased, different studies observed only a modest and inconsistent improvement in cerebral oxygenation after RBCT and raised serious concerns about the risk of increased complications. Thus, considering this "blood transfusion anemia paradox", the optimal hemoglobin level to trigger RBCT in brain-injured patients has not been defined yet; also, there is insufficient evidence to provide strong recommendations regarding which hemoglobin level to target and which associated transfusion strategy (restrictive versus liberal) to select in this patient population. We summarize in this review article the more relevant studies evaluating the effects of anemia and RBCT in patients with an acute neurological condition; also, we propose some potential strategies to optimize transfusion management in such patients.

Anemia in Intensive Cardiac Care Unit patients - An underestimated problem

The heterogeneous group of patients admitted to Intensive Cardiac Care Unit (ICCU) as well as nonspecific complaints associated with anemia might be the reason for underdiagnosing or minimization of this problem. Because of this heterogeneity, there are no clear guidelines to follow. It is known that anemia is impairing the outcome. Thus, it is crucial to keep alert in the diagnosis and treatment of anemia, especially in critically ill cardiac patients. The greatest groups of patients admitted to ICCU are those with acute coronary syndromes (ACS), acute decompensated heart failure (ADHF), severe arrhythmias as well as individuals after cardiac operations. However, patients suffering other critical cardiac illnesses quite often become anemic during hospitalization in ICCU. It is because anemia is typed in the clinical features of heavy diseases or may be the consequence of treatment. The current review focuses on the incidence, complex etiology and predictive role of anemia in a diverse group of ICCU patients. It discusses clinical aspects of anemia treatment in particular groups of critically ill cardiac patients because proper treatment increases chances for recovery and improves the outcome in this severe group of patients.

Major burn injury is not associated with acute traumatic coagulopathy

BACKGROUND

The pathophysiology and time course of coagulopathy after major burns are inadequately understood. Our study objectives were to determine whether acute traumatic coagulopathy (ATC) is seen in burn patients at admission and to determine the changes in international normalized ratio (INR), activated partial thromboplastin time (aPTT), platelet count (PLT), and hemoglobin (Hgb) in the first 7 days after injury.

METHODS

We conducted a retrospective study of patients with burn injury of at least 15% total body surface area who presented to the University of North Carolina. Data on patient demographics, injury characteristics, and laboratory data (INR, aPTT, PLT, and Hgb) at admission and within the first 7 days after injury were recorded. We defined ATC as INR of 1.3 or greater, aPTT of 1.5 or greater times the mean normal limit, and normal PLT at admission.

RESULTS

We studied the hematologic profile of 102 patients with burn injury of 15% to 100% total body surface area but did not identify a single patient with ATC at admission. The screening hematologic profile at admission was not influenced by burn severity. In the first 7 days after injury, the INR and aPTT were relatively preserved, while the PLT quickly recovered to baseline after an early decline and the Hgb remained stable at around 10 g/dL; all these changes occurred during the time when the burn patients had received large amounts of fluid resuscitation.

CONCLUSION

The screening hematologic profile of burn patients at admission is normal, and the standard screening assays do not suggest the existence of ATC at admission. While this is a relatively small study, it provides evidence to suggest that ATC is unique to trauma patients.

LEVEL OF EVIDENCE

Prognostic study, level III.