Causes and time course of acute hemolysis after burn injury in the rat

Evolution of hematocrit in burn patients as a marker of early fluid management during acute phase

OBJECTIVE

To evaluate the value of hematocrit for monitoring fluid resuscitation of burn patients in the acute phase of their care.

METHOD

We conducted a single-center retrospective study focused on patients admitted with a burn surface of more than 20 % of the total body surface area (TBSA) from 2014 to 2021. We investigated the relationship between the change in hematocrit and the volume administered for patient resuscitation. The change in hematocrit is the difference between an admission hematocrit and a second one taken between the eighth and twenty-fourth hour.

RESULTS

We included 230 patients with an average burn size of 39.1 ± 20.3 % TBSA, in 94.4 % by a thermal mechanism. The management seems to be in accordance with the current recommendations, with a volume administered during the first 24 h of 4.3 ± 2.5 ml/kg/ % BSA, allowing to obtain an hourly diuresis of 0.9 ± 0.7 ml/kg/h. We did not find any correlation between the pre-hospital volume administration and the hematocrit at admission (p = 0.36). Hematocrit decreased on average to -4.5 ± 8.1 % between admission and a control performed after the 8th hour. This decrease was weakly correlated with the volumes infused between the two samples (r2 =0.13, p < 0.001). A resuscitation above 5.2 ml/kg/ % Burn surface area is an independent factor for excess mortality.

CONCLUSION

Hematocrit or its variations in our limited data base appears to not reliably detect over-resuscitation, therefore it is possible that it may not be a relevant marker. These conclusions should be clarified in a multi-institutional prospective or real-world analysis to validate the findings and null hypothesis.

Combination of HBA1, TTR, and SERPINF2 in plasma defines phenotype correlated with severe burn outcome

Recent advancements in proteomics allow for the concurrent identification and quantification of multiple proteins. This study aimed to identify proteins associated with severe burn pathology and establish a clinically useful molecular pathology classification. In a retrospective observational study, blood samples were collected from severe burn patients. Proteins were measured using mass spectrometry, and prognosis-related proteins were extracted by comparing survivors and non-survivors. Enrichment and ROC analyses evaluated the extracted proteins, followed by latent class analysis. Measurements were performed on 83 burn patients. In the non-survivor group, ten proteins significantly changing on the day of injury were associated with metabolic processes and toxin responses. ROC analysis identified HBA1, TTR, and SERPINF2 with AUCs > 0.8 as predictors of 28-day mortality. Latent class analysis classified three molecular pathotypes, and plasma mass spectrometry revealed ten proteins associated with severe burn prognosis. Molecular pathotypes based on HBA1, TTR, and SERPINF2 significantly correlated with outcomes.

Engineering Therapeutics to Detoxify Hemoglobin, Heme, and Iron

Hemolysis (i.e., red blood cell lysis) can increase circulatory levels of cell-free hemoglobin (Hb) and its degradation by-products, namely heme (h) and iron (Fe). Under homeostasis, minor increases in these three hemolytic by-products (Hb/h/Fe) are rapidly scavenged and cleared by natural plasma proteins. Under certain pathophysiological conditions, scavenging systems become overwhelmed, leading to the accumulation of Hb/h/Fe in the circulation. Unfortunately, these species cause various side effects such as vasoconstriction, hypertension, and oxidative organ damage. Therefore, various therapeutics strategies are in development, ranging from supplementation with depleted plasma scavenger proteins to engineered biomimetic protein constructs capable of scavenging multiple hemolytic species. In this review, we briefly describe hemolysis and the characteristics of the major plasma-derived protein scavengers of Hb/h/Fe. Finally, we present novel engineering approaches designed to address the toxicity of these hemolytic by-products.

An Increase in Admission RDW Value Is Associated with Excess Short-Term Mortality Rates in Patients with Severe Burns

The predictive value of red blood cell distribution width (RDW) in severely burned patients remains unclear. This study aimed to investigate the potential association between admission RDW and outcomes in patients with severe burns. Data of severely burned patients in the burn center of Changhai Hospital were retrospectively evaluated. The relationship between admission RDW and mortality was analyzed and displayed using the receiver operating characteristic curve, Kaplan-Meier curve, Cox proportional hazards regression, and the nomogram method. A total of 342 patients were identified according to the filter criteria. The 30-day mortality was 12.9%, and the mortality rates in 7 days and 90 days were 2.9% and 16.7%, respectively. Patients with high admission RDW value were more likely to die than those with low RDW value. Multivariate analysis revealed that higher admission RDW, age, full-thickness burned area, and inhalation injury were independent risk factors with 30-day mortality. The nomogram based on these risk factors was established to predict survival probability in severe burn patients. The C-index of different follow-up times was computed between 0.867 and 0.904, and the nomogram model list fits the data well. Admission RDW played a valuable role in predicting short-term mortality in patients with severe burns. The nomogram containing admission RDW was established to predict mortality, which helps burn care providers identify the patients at higher risk of short-term mortality after severe burns. More attention should be paid to the application of these easy and inexpensive biochemical indicators in the early prediction of disease progression.

Sodium nitrite potentiates renal oxidative stress and injury in hemoglobin exposed guinea pigs

Methemoglobin-forming drugs, such as sodium nitrite (NaNO2), may exacerbate oxidative toxicity under certain chronic or acute hemolytic settings. In this study, we evaluated markers of renal oxidative stress and injury in guinea pigs exposed to extracellular hemoglobin (Hb) followed by NaNO2 at doses sufficient to simulate clinically relevant acute methemoglobinemia. NaNO2 induced rapid and extensive oxidation of plasma Hb in this model. This was accompanied by increased renal expression of the oxidative response effectors nuclear factor erythroid 2-derived-factor 2 (Nrf-2) and heme oxygenase-1 (HO-1), elevated non-heme iron deposition, lipid peroxidation, interstitial inflammatory cell activation, increased expression of tubular injury markers kidney injury-1 marker (KIM-1) and liver-fatty acid binding protein (L-FABP), podocyte injury, and cell death. Importantly, these indicators of renal oxidative stress and injury were minimal or absent following infusion of Hb or NaNO2 alone. Together, these results suggest that the exposure to NaNO2 in settings associated with increased extracellular Hb may potentiate acute renal toxicity via processes that are independent of NaNO2 induced erythrocyte methemoglobinemia.

Contribution of forensic autopsy to scene reconstruction in mass fire casualties: a case of alleged arson on a floor consisting of small compartments in a building

A fire is an important cause of mass disasters, involving various forensic issues. Before dawn on an early morning, 16 male visitors in their twenties to sixties were killed in a possibly incendiary fire at a 'private video parlor' consisting of small compartments in a building. The main causes of death as determined by forensic autopsy were acute carbon monoxide (CO) intoxication for all of the 15 found-dead victims, and hypoxic-ischemic encephalopathy following acute CO intoxication for a victim who died in hospital. Burns were mild (<20% of body surface) in most victims, except for three victims found between the entrance and the estimated fire-outbreak site; thus, identification was completed without difficulty, supported by DNA analysis. Blood carboxyhemoglobin saturation (COHb) was higher for victims found dead in the inner area. Blood cyanide levels were sublethal, moderately correlated to COHb, but were higher in victims found around the estimated fire-outbreak site. There was no evidence of thinner, alcohol or drug abuse, or an attack of disease as a possible cause of an accidental fire outbreak. These observations contribute to evidence-based reconstruction of the fire disaster, and suggest how deaths could have been prevented by appropriate disaster measures.

Inhibition of p38 MAP kinase improves survival of cardiac myocytes with hypoxia and burn serum challenge

This study was aimed to investigate the effects of SB203580, the specific p38 mitogen-activated protein (MAP) kinase inhibitor, on cardiac myocyte survival and secretion of cytokines in an in vitro model of hypoxia and burn serum challenge. Results demonstrated that hypoxia and burn serum induced a persistent activation of p38 MAP kinase in primary cultured neonatal rat cardiomyocytes during the 12h period of stimulation, concomitant with a time-dependent increased expression of tumor necrosis factor (TNF)-alpha and inducible nitric oxide (iNOS), a progressively developed oxidative stress reflected by malondialdehyde (MDA) production, and myocytes injury evidenced by the increased levels of released lactate dehydrogenase (LDH) and the decreased myocyte viability. Furthermore, hypoxia and burn serum resulted in a significant increase in myocyte apoptosis, which may account for the impairment of myocyte viability as observed. SB203580 abolished p38 MAP kinase activation, blunted the upregulation of TNF-alpha, iNOS and the subsequent nitric oxide (NO) production, reduced oxidative stress, and alleviated hypoxia and burn serum-induced myocytes injury or apoptosis. These results demonstrated for the first time that inhibition of p38 MAP kinase improves survival of cardiac myocytes with hypoxia and burn serum challenge possibly via reducing the production of cytokines, such as TNF-alpha and NO, and the subsequent oxidative stress, providing strong evidence that the excessive inflammatory cytokines produced by cardiomyocytes themselves may be sufficient to cause myocardial injury after burn.

Intravascular hemolysis associated with severe cutaneous burn injuries in five horses

Five horses were evaluated because of severe cutaneous burn injuries following a barn fire. Gross hemolysis and morphologic changes in RBCs consistent with oxidative damage were detected in all of the horses. Of these horses, 4 became azotemic. The overall goals of treatment included wound care, correction of dehydration and provision of diuresis, control of inflammation, pain management, and prophylaxis against sepsis. After treatment, 2 horses survived and were discharged from the hospital. Red blood cell damage and hemolysis following cutaneous burn injury have been investigated in other species and appear to be a result of the release of oxygen radicals from complement-activated neutrophils. Early intervention with aggressive fluid therapy is recommended in the treatment of human burn patients and is likely to be of benefit in horses with burn injuries; a beneficial role of free radical scavengers and xanthine oxidase inhibitors has also been suggested.

Burn-induced red blood cell deformability and shape changes are modulated by sex hormones

BACKGROUND

Burns are known to cause changes in red blood cell (RBC) deformability and resting shape. However, it is unclear whether sex and sex hormones can influence the severity of these alterations.

METHODS

Red blood cell deformability and shape were examined in proestrus and diestrus female rats, ovariectomized female rats, as well as castrated and non-castrated male rats (6 animals per group) subjected to scald burn. Red blood cell deformability was measured by laser ektacytometry and erythrocyte shape was evaluated by scanning electron microscopy.

RESULTS

Burn-induced RBC deformability changes (decrease in elongation index) and shape alterations (increase in the percentage of reversibly and irreversibly changed cells) were less severe in proestrus females than in diestrus females or males. Ovariectomized rats demonstrated more severe RBC changes than non-ovariectomized ones. The degree of RBC damage was the same in castrated and non-castrated males.

CONCLUSIONS

Removal of female sex hormones increases the severity of burn-induced RBC, indicating that female sex hormones protect against burn-induced RBC dysfunction. In contrast, male sex hormones do not appear to modulate burn-induced RBC dysfunction.

Effects of hypoxia and glutathione depletion on hemoglobin- and myoglobin-mediated oxidative stress toward endothelium

We investigated the toxicity of hemoglobin/myoglobin on endothelial cells under oxidative stress conditions that include cellular hypoxia and reduced antioxidant capacity. Bovine aorta endothelial cells (BAECs), grown on microcarrier beads, were subjected to cycles of hypoxia and reoxygenation in a small volume of medium, and endothelial cell monolayers were depleted of their intracellular glutathione (GSH) by treatment with buthionine sulfoximine. Incubation of diaspirin cross-linked hemoglobin (DBBF-Hb) or horse skeletal myoglobin (Mb) with BAECs subjected to 3 h of hypoxia caused transient oxidation of the hemoproteins to the ferryl form (Fe(4+)). Formation of the ferryl intermediate was decreased in a concentration-dependent manner by the addition of L-arginine, a substrate of NO synthase, after 3 h of hypoxia. Optimal inhibition of ferryl formation, possibly due to the antioxidant action of NO, was achieved with 900 microM L-arginine. Addition of hydrogen peroxide to GSH-depleted cells in the presence of DBBF-Hb or Mb significantly decreased cell viability. Ferryl Mb, but not ferryl DBBF-Hb, was observed in samples analyzed at the end of treatment, which may explain the greater toxicity observed with Mb as opposed to DBBF-Hb. This model may be utilized to identify causative agent(s) associated with hemoprotein cytotoxicity and in designing strategies to suppress or control heme-mediated injury under physiologically relevant conditions.

Suppressive effect of FC-43 perfluorocarbon emulsion on enhanced oxidative haemolysis in the early postburn phase

The effect of FC-43 perfluorocarbon emulsion on resistance of red blood cells to oxidative haemolysis and lipid peroxidation was evaluated in rats (full skin thickness burns over 15-20 per cent of total body surface area). The content of erythrocyte malonyl dialdehyde (MDA), alpha-tocopherol, glutathione (reduced and oxidized forms) and oxidative haemolysis were measured at 24 h after burn injury. Four groups were employed: (1) non-burned non-treated, (2) non-burned but treated with FC-43 perfluorocarbon emulsion (5 ml/kg bodymass i.v.), (3) burned non-treated, (4) burned but treated with FC-43 emulsion (5 ml/kg bodymass i.v.). The non-burned groups showed no significant differences in oxidative haemolysis, MDA levels or alpha-tocopherol and glutathione content. In the burned non-treated group the oxidative haemolysis elevated by 190 per cent (P < 0.001), MDA content increased by 43 per cent (P < 0.05), whereas the concentration of alpha-tocopherol and reduced glutathione (GSH) decreased significantly by 36 per cent and 18 per cent, respectively. The results showed reduction in the postburn MDA content by 30 per cent (P < 0.02) and oxidative haemolysis by 44 per cent (P < 0.001) after treatment with FC-43 emulsion. FC-43 emulsion did not change significantly the levels of alpha-tocopherol and GSH in erythrocytes after thermal injury. It is concluded that FC-43 perfluorocarbon emulsion administration suppresses early postburn lipid peroxidation and increases the resistance of red blood cells to oxidative haemolysis.

Increased antioxidant capacity, suppression of free radical damage and erythrocyte aggrerability after combined application of alpha-tocopherol and FC-43 perfluorocarbon emulsion in early postburn period in rats

Certain rheological disorders such as enhanced aggregation and reduced deformability of erythrocytes are closely associated with microcirculatory disturbances, decreased tissue oxygen supply and represent a major problem in severely burnt patients [1-4]. Vitamin E (alpha-tocopherol) and vitamin A (retinol) exert an important plasma antioxidant properties against free radical-induced damage [11,12]. They possess chain-breaking properties and act as synergists [13]. Plasma antioxidant capacity may be decreased in severely burnt patients as a result of the enhanced consumption and inadequate restoration of antioxidants in the conditions of activated peroxidative process [14]. Treatment with alpha-tocopherol suppresses lipid peroxidation in blood and therefore improves erythrocyte rheology [15]. Perfluorocarbon emulsions improve microcirculation and rheological blood properties [16-18] and preserve the structure and function of endothelial cells [19]. The very small particle size, low viscosity and high oxygen carrying capacity ensure their penetration into the microvasculature even under conditions of ischemia and acidosis [20, 21]. Perfluorocarbons have been reported to inhibit leukocyte activation and superoxide radical production [22]. The aim of the present study was to examine the antioxidant capacity, free radical mediated damage and erythrocyte aggregation in plasma of rats with thermal skin injury in the early postburn period and to evaluate the effect of treatment with alpha-tocopherol and FC-43 perfluorocarbon emulsion alone and in combination. We might conclude that thermal skin injury in rats reduces the antioxidant capacity, enhances free radical mediated damage and erythrocyte aggregation on the third hour after injury. The combined application of alpha-tocopherol and FC-43 perfluorocarbon emulsion immediately after thermal skin injury in rats increases plasma antioxidant capacity, decreases free radical mediated damage of erythrocytes and suppresses their aggregation on the third hour after the injury.