Early clinical complete blood count changes in severe burn injuries

Skin graft surgery and its impact on platelet counts in Iranian burn patients: a non-randomized clinical trial

BACKGROUND

Platelets are critical in maintaining homeostasis and immune response in burn patients. The concentration of platelets decreases in burn patients, and any intervention that increases serum platelet concentration can prevent serious consequences and patient death. The present study aimed to assess the impact of skin graft surgery on burn patients' platelet counts.

METHODS

In this non-randomized clinical trial, 200 burn patients were investigated. The patients were recruited from the surgical ward of Imam Khomeini Teaching Hospital during the first six months of 2021. After completing the checklist, patients underwent skin graft surgery. Blood was taken from the patients during surgery in the operating room and on the third and fifth day after the surgery to check platelets. Data analysis was conducted using SPSS software (ver. 22.0).

RESULTS

Most patients (63.5%) were male, and 73 (36.5%) were female. One hundred eighty-one patients (90.5%) had deep burns, and 19 (9.5%) had superficial burns. The mean burns percentage in the patients was 19.3 ± 15.4%, the lowest was 2%, and the highest was 90%. The most common burns were caused by flame (42%) and boiling water (30.5%). The patients' outcomes revealed that 6% gained complete recovery, 86.5% partial recovery, 2.5% showed transplant rejection, and 5% died. Mean platelet levels in deceased patients had an upward trend. The mean platelet counts of patients were elevated during surgery (289,855 ± 165,378), decreased three days after surgery (282,778 ± 317,310), and elevated again five days after surgery (330,375 ± 208,571). However, no significant difference was found between the mean platelet counts during surgery, the third and fifth days after surgery in patients undergoing skin grafts (P = 0.057).

CONCLUSIONS

This study suggests that skin graft positively increases the patient's platelets. Further studies are needed to confirm the findings and elucidate the mechanism. Iranian Registry of Clinical Trial approval code (IRCT# IRCT20131112015390N8 & 06/01/2024).

A Murine Model of Vesicant-Induced Acute Lung Injury

Burn injuries including those caused by chemicals can result in systemic effects and acute lung injury (ALI). Cutaneous exposure to Lewisite, a warfare and chemical burn agent, also causes ALI. To overcome the limitations in conducting direct research on Lewisite-induced ALI in a laboratory setting, an animal model was developed using phenylarsine oxide (PAO) as a surrogate for Lewisite. Due to lack of a reliable animal model mimicking the effects of such exposures, development of effective therapies to treat such injuries is challenging. We demonstrated that a single cutaneous exposure to PAO resulted in disruption of the alveolar-capillary barrier as evidenced by elevated protein levels in the bronchoalveolar lavage fluid (BALF). BALF supernatant of PAO-exposed animals had increased levels of high mobility group box 1, a damage associated molecular pattern molecule. Arterial blood-gas measurements showed decreased pH, increased PaCO2, and decreased partial pressure of arterial O2, indicative of respiratory acidosis, hypercapnia, and hypoxemia. Increased protein levels of interleukin (IL)-6, CXCL-1, CXCL-2, CXCL-5, granulocyte-macrophage colony-stimulating factor, CXCL-10, leukemia inhibitory factor, leptin, IL-18, CCL-2, CCL-3, and CCL-7 were observed in the lung of PAO-exposed mice. Further, vascular endothelial growth factor levels were reduced in the lung. Pulmonary function evaluated using a flexiVent showed a downward shift in the pressure-volume loop, decreases in static compliance and inspiratory capacity, increases in respiratory elastance and tissue elastance. These changes are consistent with an ALI phenotype. These results demonstrate that cutaneous PAO exposure leads to ALI and that the model can be used as an effective surrogate to investigate vesicant-induced ALI. SIGNIFICANCE STATEMENT: This study presents a robust model for studying ALI resulting from cutaneous exposure to PAO, a surrogate for the toxic vesicating agent Lewisite. The findings in this study mimic the effects of cutaneous Lewisite exposure, providing a reliable model for investigating mechanisms underlying toxicity. The model can also be used to develop medical countermeasures to mitigate ALI associated with cutaneous Lewisite exposure.

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.

Cost analysis of severe burn victims in Southwest China: A 7-year retrospective study

Background

Severe burn injury can be a life-threatening experience and can also lead to financial issues for suffers. The purpose of the current study was to analyze the direct hospitalization costs of severe burn inpatients in Southwest China.

Methods

Data related to all inpatients admitted with severe burns [total body surface area (TBSA) ≥30%] pooled from 2015 to 2021 were reviewed retrospectively at the Institute of Burn Research of Army Medical University. Demographic parameters, medical economics, and clinical data were obtained from medical records.

Results

A total of 668 cases were identified. The average age was 37.49 ± 21.00 years, and 72.3% were men. The average TBSA was 51.35 ± 19.49%. The median length of stay of inpatients in the burn intensive care unit was 14 [interquartile range (IQR): 5.0-34.8] days, and the median length of stay (LOS) was 41 (IQR: 22.0-73.8) days. The mortality rate was 1.6%. The median total cost was 212,755.45 CNY (IQR: 83,908.80-551,621.57 CNY) per patient varying from 3,521.30 to 4,822,357.19 CNY. The direct cost of scald burns was dramatically lower compared with that of other types of burns, with 11,213.43 to 2,819,019.14 CNY. Medical consumables presented the largest portion of total costs, with a median cost of 65,942.64 CNY (IQR: 18,771.86-171,197.97 CNY). The crucial risk factors for medical cost in our study were TBSA, surgical frequency, LOS, depth of burn, and outcome.

Conclusion

We conclude that an effective burn prevention program, shorter hospital stays, and facilitating the healing of wounds should be focused on with tailored precautionary protocols to reduce the medical costs of inpatients with severe burns.

A Case of Necrotizing Fasciitis Mimicking a Burn in an Elderly Patient

Necrotizing fasciitis travels along the fascial plane and surrounding soft tissue, leading to ischemia and necrosis. Fournier's gangrene is a type of necrotizing fasciitis invading the deep and superficial planes of the perineal/genital region. It is rapidly progressive in nature and may have life-threatening consequences. Fournier's often exhibits a misleading clinical presentation and can be mistaken for other conditions, such as hematoma, phlebitis, cellulitis, or septic arthritis. Since the ramifications of delayed diagnosis can be clinically significant, recognition of potential mimics is important to prevent morbidity or mortality. We report a case of Fournier's gangrene mimicking a second-degree burn, an exceedingly rare presentation.

Hiding in plain sight? A review of post-convulsive leukocyte elevations

During physiological stress responses such as vigorous exercise, emotional states of fear and rage, and asphyxia, the nervous system induces a massive release of systemic catecholamines that prepares the body for survival by increasing cardiac output and redirecting blood flow from non-essential organs into the cardiopulmonary circulation. A curious byproduct of this vital response is a sudden, transient, and redistributive leukocytosis provoked mostly by the resultant shear forces exerted by rapid blood flow on marginated leukocytes. Generalized convulsive seizures, too, result in catecholamine surges accompanied by similar leukocytoses, the magnitude of which appears to be rooted in semiological factors such as convulsive duration and intensity. This manuscript reviews the history, kinetics, physiology, and clinical significance of post-convulsive leukocyte elevations and discusses their clinical utility, including a proposed role in the scientific investigation of sudden unexpected death in epilepsy (SUDEP).

The relationships between routine admission blood tests and burn size, and length of stay in intensive care unit

BACKGROUND

Although blood test is a routine in major burns, its relationship with burn size and intensive care unit length of stay (ICULOS) remains undetermined. We investigated the feasibility of using these tests as a reference for definite diagnosis of major burn size, burn size >20% of the total body surface area (TBSA), and their relationships with ICULOS.

METHODS

Data of routine laboratory blood tests within 24 h after burns (n = 73) were collected retrospectively. Correlation tests and regression analyses were performed.

RESULTS

Burns ≥20 TBSA had higher incidences of leucocytosis, hypoalbuminaemia, elevated haemoglobin (Hb), and elevated haematocrit (Hct). Burn size was correlated negatively with albumin but positively with Hb, Hct, and white blood cell (WBC) count. For each unit increase in blood urea nitrogen (BUN)/creatinine (Cr), there was an increase of 1.2 days of ICULOS in females, while in males, there was a 6.7 day increase for every unit increase in Hb and a 3.1 day increase for each unit increase in BUN. A female model including Hb and WBC was derived, discriminating burns ≥20 TBSA with sensitivity and specificity 0.94 and 1.0 respectively, and area under the receiver operating characteristic curve (AUROC) 0.96 (95% CI 0.91-1.00). The male model had sensitivity 0.96, specificity 1.0, and AUROC 0.96 (95% CI 0.89-1.00).

CONCLUSION

Admission Hb and WBC could be used as a reference for definite diagnosis of major burn size, especially in borderline cases. BUN/Cr in females, and Hb and BUN in males, were related to ICULOS.

Burn-Induced Local and Systemic Immune Response: Systematic Review and Meta-Analysis of Animal Studies

As burn injuries are often followed by a derailed immune response and excessive inflammation, a thorough understanding of the occurring reactions is key to prevent secondary complications. This systematic review, that includes 247 animal studies, shows the post-burn response of 14 different immune cell types involved in immediate and long-term effects, in both wound tissue and circulation. Peripheral blood neutrophil and monocyte numbers increased directly after burns, whereas thrombocyte numbers increased near the end of the first week. Lymphocyte numbers, however, were decreased for at least two weeks. In burn wound tissue, neutrophil and macrophage numbers accumulated during the first three weeks. Burns also altered cellular functions as we found increased migratory potential of leukocytes, impaired antibacterial activity of neutrophils and enhanced inflammatory mediator production by macrophages. Neutrophil surges were positively associated with burn size and were highest in rats. Altogether, this comprehensive overview of the temporal immune cell dynamics shows that unlike normal wound healing, burn injury induces a long-lasting inflammatory response. It provides a fundamental research basis to improve experimental set-ups, burn care and outcome.

Prognostic Values of Platelet Distribution Width and Platelet Distribution Width-to-Platelet Ratio in Severe Burns

BACKGROUND

Platelet distribution width (PDW) and PDW-to-platelet ratio (PPR) have been proven to be good prognostic indicators for many diseases. However, their prognostic values in severe burns have not been reported.

OBJECTIVE

To investigate the early time course of PDW and PPR in severe burn patients and investigate their prognostic values.

METHODS

This is a 16-year, single-center retrospective study of 590 severe burn patients. The complete blood count parameters on day 1, day 3, and day 7 postburn, including PDW and PPR, were collected. Receiver operating characteristic curves (ROC) analysis, multiple logistic regression analysis and Kaplan-Meier survival analysis were performed to evaluate the prognostic values of PDW and PPR in severe burn patients.

RESULTS

According to 120-day follow-up records, 96 patients were nonsurvivors and 494 patients were survivors. ROC and area under the curve (AUC) analysis showed that, for predicting 120-day prognosis, the AUC of PDW (0.782) and PPR (0.816) on day 3 was the highest, followed by the AUC of PDW (0.764) and PPR (0.750) on day 7. The ROC-AUC of PPR (0.816) on day 3 was very close to that of the ABSI score (0.818). Multiple logistic regression analysis showed that the PDW (P = 0.033 and P = 0.009) and PPR (P = 0.052 and P = 0.046) on day 3 and day 7 were all significantly independently positively associated with 120-day mortality. Kaplan-Meier survival analysis showed that high PDW and PPR were both significantly associated with a high 120-day mortality rate on day 3 and day 7.

CONCLUSION

PDW and PPR on day 3 and day 7 were independent risk factors for 120-day mortality in severe burn patients. These objective and readily available prognostic indicators may be more clinically favored.

Investigation of red cell distribution width as a prognostic criterion in severe burns

This study was conducted to examine red cell distribution width (RDW) as a prognostic criterion in severe burns. The study is a descriptive correlational study and was carried out retrospectively. Patients with high RDW and low albumin values among severe burn injuries in the burn unit of a university hospital constituted half of the sample. Severe burns with RDW within normal range and a prognostic criterion for which albumin level normal and closest to normal accounted for the other half. RDW and albumin values were compared with the clinical results of patients with severe burns. IBM SPSS (Statistical Package for the Social Sciences) Statistics 25 was used for data analysis. Of the burn patients, 38.33% were between the age of 65–80, 51.67% were men, and 92.5% had third‐degree burns. The mean albumin level of the patients was 2.39 ± 0.34 g/dL, and the mean RDW level was 18.47 ± 6.15%. The length of the stay in the intensive care unit was 13.45 ± 7.83 days, and the duration of central venous catheter use was 23.41 ± 8.25 days. High RDW and low albumin values were found to be associated with death, length of stay in the intensive care unit, and more blood transfusion. High RDW and hypoalbuminemia significantly affect the clinical results of severe burns. Both parameters are effective in determining the clinical course of burn patients, the length of hospital stay, presence of catheters and medication treatment protocol.

Possible indicators of amputation and insufficient perfusion after heat press injury: A retrospective study

INTRODUCTION

Amputation outcome after heat press injury is associated with insufficient perfusion. We aimed to determine other risk factors for heat press injury and mechanisms of insufficient perfusion associated with amputation.

METHODS

We retrospectively classified 120 inpatients into the emergency and clinic groups, with arrival time before and after 48 h of injury, respectively. We performed propensity score-match to identify significant variables and combine them with those previously identified. Patients with or without amputation were categorized in different subgroups according to arrival time and perfusion with receiver-operator-characteristic (ROC) curves.

RESULTS

In the emergently insufficient perfusion subgroup, red blood cell distribution width of standard deviation (RDW-SD) was statistically different between patients without and with amputation (cutoff = 43 fL; specificity = 0.909). In the urgent group, neutrophil-lymphocyte-ratio (NLR) and relative lymphocyte count (L%) showed no association with perfusion, but was associated with amputation (NLR cutoff value = 3.12; sensitivity = 0.846). Differential leukocytes and related ratios (both groups), D-dimer (emergency group), and creatine kinase (CK) (clinic group) were also associated with insufficient perfusion.

CONCLUSION

The study showed some correlations. Inflammation variables, D-dimer, and CK were associated with amputation and perfusion after heat press injury. Several factors were associated with amputation, including RDW-SD increase in insufficiently perfused patients within 48 h of injury, and NLR increase and L% decrease in patients after 48 h post-injury.

Quantitative Evaluation of Burn Injuries Based on Electrical Impedance Spectroscopy of Blood with a Seven-Parameter Equivalent Circuit

A quantitative and rapid burn injury detection method has been proposed based on the electrical impedance spectroscopy (EIS) of blood with a seven-parameter equivalent circuit. The degree of burn injury is estimated from the electrical impedance characteristics of blood with different volume proportions of red blood cells (RBCs) and heated red blood cells (HRBCs). A quantitative relationship between the volume portion H_HCT of HRBCs and the electrical impedance characteristics of blood has been demonstrated. A seven -parameter equivalent circuit is employed to quantify the relationship from the perspective of electricity. Additionally, the traditional Hanai equation has been modified to verify the experimental results. Results show that the imaginary part of impedance Z_Imt under the characteristic frequency (f_c) has a linear relationship with H_HCT which could be described by Z_Imt = −2.56H_HCT − 2.01 with a correlation coefficient of 0.96. Moreover, the relationship between the plasma resistance R_p and H_HCT is obtained as R_p = −7.2H_HCT + 3.91 with a correlation coefficient of 0.96 from the seven -parameter equivalent circuit. This study shows the feasibility of EIS in the quantitative detection of burn injury by the quantitative parameters Z_Imt and R_p, which might be meaningful for the follow-up clinical treatment for burn injury.

Low-soluble TREM-like transcript-1 levels early after severe burn reflect increased coagulation disorders and predict 30-day mortality

BACKGROUND

Patients with severe burns often show systemic coagulation changes in the early stage and even develop extensive coagulopathy. Previous studies have confirmed that soluble TREM-like transcript-1 (sTLT-1) mediates a novel mechanism of haemostasis and thrombosis in inflammatory vascular injury. At present, the role of sTLT-1 in patients with severe burns is not well known.

OBJECTIVE

To investigate the early association between sTLT-1 levels and markers of burn severity, coagulation disorders, endothelial permeability, shock and prognosis in patients with severe burns.

METHODS

A prospective, observational study was conducted with 60 severe burn patients (divided into a death group and a survival group according to 30-day prognosis) admitted to our hospital. Twenty-eight healthy volunteers were recruited as the control group. Blood components at 48 h after burn were analysed for sTLT-1 and biomarkers reflecting platelet activation, shock, endothelial glycocalyx damage, capillary leakage, haemostasis, fibrinolytic activity, natural anticoagulation and blood cells. We compared the three groups, analysed the correlation between sTLT-1 and biomarkers, and investigated the predictive value of sTLT-1 for 30-day prognosis.

RESULT

Compared with the surviving patients, the patients who died had a lower degree of platelet activation [lower sTLT-1, platelet factor 4 (PF-4) and platelet counts] and a higher degree of burn [higher abbreviated burn severity index score (ABSI score)], shock (higher lactate), endothelial glycocalyx damage [higher syndecan-1 and soluble thrombomodulin (sTM)] and capillary leakage [higher resuscitation fluid (0-48 h), lower albumin] as well as decreased haemostasis [higher activated partial prothrombin time (APTT), lower fibrinogen and thrombin-antithrombin III complex (TAT)], increased fibrinolytic activity [higher D-dimer and tissue-type plasminogen activator (tPA)] and decreased natural anticoagulation [lower protein C (PC) and protein S (PS)]. Higher D-dimer (P = 0.013) and lower PF-4 (P = 0.001) were significantly independently associated with lower sTLT-1. Low circulating sTLT-1 (a unit is 50 pg/mL) (odds ratio [OR] 2.08 [95% CI 1.11-3.92], P = 0.022) was an independent predictor of increased 30-day mortality.

CONCLUSION

Low sTLT-1 levels at 48 h after burn in patients with severe burns is associated with increased coagulation disorders. Low circulating sTLT-1 levels were an independent predictor of increased 30-day mortality.

Fibrinolysis Index as a new predictor of deep vein thrombosis after traumatic lower extremity fractures

BACKGROUND

Deep vein thrombosis (DVT) is a common complication in patients with traumatic injury. The purpose of this study was to develop a potential predictor of DVT.

METHODS

This case-control study enrolled adult trauma patients and healthy volunteers. Patients underwent angiography before surgery to diagnose DVT. Patients with or without DVT were matched by gender, age and fracture sites. Laboratory parameters included lysis potential (LP), lysis time (LT), blood cell counts, conventional coagulation tests, tissue plasminogen activator inhibitor complex (tPAIC) and others.

RESULTS

41 of 319 patients with DVT were matched with 41 patients without DVT and 80 healthy volunteers were controls. LP and LT were significantly decreased in patients with DVT than without (P = 0.043 and P = 0.014, respectively). The level of tPAIC in the DVT group was significantly higher than in patients without DVT (P = 0.042). We defined the Fibrinolysis Index as (-10.707) × LP + (-0.607) × LT (min) + 0.012 × fibrinogen (mg/dl) + 0.299 × tPAIC (ng/ml) + 9.917, and found that the area under the receiver operating characteristic curve for the Fibrinolysis Index was 0.802, making it a novel indicator.

CONCLUSION

The Fibrinolysis Index represents a new discriminator for predicting DVT after traumatic lower extremity fractures.

Novel application of an automated-machine learning development tool for predicting burn sepsis: proof of concept

Sepsis is the primary cause of burn-related mortality and morbidity. Traditional indicators of sepsis exhibit poor performance when used in this unique population due to their underlying hypermetabolic and inflammatory response following burn injury. To address this challenge, we developed the Machine Intelligence Learning Optimizer (MILO), an automated machine learning (ML) platform, to automatically produce ML models for predicting burn sepsis. We conducted a retrospective analysis of 211 adult patients (age ≥ 18 years) with severe burn injury (≥ 20% total body surface area) to generate training and test datasets for ML applications. The MILO approach was compared against an exhaustive “non-automated” ML approach as well as standard statistical methods. For this study, traditional multivariate logistic regression (LR) identified seven predictors of burn sepsis when controlled for age and burn size (OR 2.8, 95% CI 1.99–4.04, P = 0.032). The area under the ROC (ROC-AUC) when using these seven predictors was 0.88. Next, the non-automated ML approach produced an optimal model based on LR using 16 out of the 23 features from the study dataset. Model accuracy was 86% with ROC-AUC of 0.96. In contrast, MILO identified a k-nearest neighbor-based model using only five features to be the best performer with an accuracy of 90% and a ROC-AUC of 0.96. Machine learning augments burn sepsis prediction. MILO identified models more quickly, with less required features, and found to be analytically superior to traditional ML approaches. Future studies are needed to clinically validate the performance of MILO-derived ML models for sepsis prediction.

Acute renal insufficiency and thrombocytopenia after high-intensity focused ultrasound (HIFU) ablation for uterine myomas

OBJECTIVE

Ultrasound-guided high-intensity focused ultrasound (USg-HIFU) has emerged in recent years as the new treatment modality for uterine myomas and adenomyosis with the advantages of being non-invasive, safe and effective. As its utility increases, adverse reactions emerge and deserve clinicians' attention for experience accrual. We herein report a case who suffered from acute renal insufficiency and thrombocytopenia immediately after receiving HIFU for uterine myomas.

CASE REPORT

A 38-year-old nulliparous healthy female received HIFU for huge uterine myoma that caused heavy vaginal bleeding and chronic anemia. The procedure went smoothly but the patient immediately suffered from oliguria and dark-colored urine. With conservative management and aggressive hydration, her condition had improved spontaneously after 1 week without leaving any long-term sequelae. Myoma size reduced by 70% 3 months post-treatment and her bleeding problems significantly improved.

CONCLUSION

This is the first report of post-HIFU acute renal failure and thrombocytopenia. Thermal injuries, drug toxicity and mechanical obstruction of ureters are some plausible explanations for speculations.

Complete Blood Count and Derived Indices: Evolution Pattern and Prognostic Value in Adult Burned Patients

Certain parameters of complete blood count (CBC) such as red cell distribution width (RDW) and mean platelet volume, as well as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and RDW-to-platelet ratio (RPR) have been associated with inflammatory status and outcome in diverse medical conditions. The aim of this study was to describe the evolution pattern of these parameters in adult burned patients. Adult burned patients admitted to the National Burn Center in Uruguay between May 2017 and February 2018 (discovery cohort) and between March 2018 and August 2019 (validation cohort) were included. Patients' characteristics and outcomes were recorded, as well as CBC parameters on days 1, 3, 5, and 7 after thermal injury. Eighty-eight patients were included in the discovery cohort. Total body surface area burned was 14 [7-23]% and mortality was 15%. Nonsurvivors presented higher RDW and mean platelet volume (P < .01). NLR decreased after admission in all patients (P < .01), but was higher in nonsurvivors (P < .01). Deceased patients also presented higher RPR on days 3, 5, and 7 (P < .001). On the contrary, PLR was reduced in nonsurvivors (P < .05). There was a significant correlation between NLR on admission and burn extension and severity. Kaplan-Meier analysis revealed that NLR, PLR, and RPR could identify patients with increased mortality. These findings were confirmed in the validation cohort (n = 95). Basic CBC parameters and derived indices could be useful as biomarkers to determine prognosis in adults with thermal injuries.

Comparative Analysis of the Host Response in a Rat Model of Deep-Partial and Full-Thickness Burn Wounds With Pseudomonas aeruginosa Infection

Burn wound injury affects soldiers and civilians alike, often resulting in a dynamic, but un-orchestrated, host response that can lead to infection, scarring, and potentially death. To mitigate these factors, it is important to have a clinically relevant model of burn wound infection that can be utilized for advancing burn wound treatments. Our previous reports have demonstrated the ability of Pseudomonas aeruginosa to generate a biofilm infection within a modified Walker-Mason rat burn model of deep-partial (DPT) and full-thickness (FT) burn wounds (10% total body surface area) in male Sprague-Dawley rats (350–450 g). Here, we further define this model with respect to the host response when challenged with P. aeruginosa infection between the two burn types. Following burn injury and immediate surface exposure to P. aeruginosa, inflammation at the local and systemic levels were monitored for an 11 days period. Compared to burn-only groups, infection with P. aeruginosa further promoted local inflammation in both DPT and FT burn wounds, which was evident by enhanced cellular influx (including neutrophils and monocytes), increased levels of several pro-inflammatory cytokines (IL-1β, IL-6, GRO/KC, andMIP-1α), and reduced IL-10. Systemically, only minor changes were seen in circulating white blood cells and cytokines; however, increases in high mobility group box-1 (HMGB-1) and hyaluronan, as well as decreases in fibronectin were noted particularly in FT burns. Compared to the burn-only group, P. aeruginosa infection resulted in sustained and/or higher levels of HMGB-1 and hyaluronan. Combined with our previous work that defined the burn depth and development of P. aeruginosa biofilms within the wound, this study further establishes this model by defining the host response to the burn and biofilm-infection. Furthermore, this characterization shows several similarities to what is clinically seen and establishes this model for future use in the development and testing of novel therapeutics for burn wound treatment at home and on the battlefield.

Natural kinetics of blood cells following major burn: Impact of early decreases in white blood cells and platelets as prognostic markers of mortality

BACKGROUND

Severely burned patients often suffer white blood cell and platelet drop following the injury. Though coagulopathy after burn injury have been reported, the association between leukopenia or thrombopenia and mortality is still unrevealed. To determine whether early drastic drops in white blood cells (WBCs) and platelets following injury can be prognostic markers in patients with major burns.

METHODS

This is a retrospective cohort study setting in a single Burn Center in Japan. Data comprising patients' characteristics and blood cell counts (red blood cells [RBCs], WBCs including neutrophils, monocytes, and lymphocytes, and platelets) over the first 30 days after burn injury were serially collected from patients suffering major burn injury (≥20% TBSA) from January 1, 2006 to December 31, 2015. To determine blood cell counts affecting 60-day mortality, we used multivariable Cox proportional hazard analysis to assess associations between each blood cell count and mortality, adjusting for age and %TBSA as covariates, and evaluated predicted value of the hazard ratio (HR) of death.

RESULTS

We enrolled 280 patients. Following burn injury, all blood cell counts were high at admission, then decreased. RBCs diminished progressively and plateaued 2 weeks after injury. WBCs decreased suddenly 2 days after injury, then increased and stabilized. Platelets decreased more rapidly than WBCs to their nadir at 3 days, then continually increased. After covariate adjustment, low RBCs from day 1 (HR: 0.566, 95% C.I. 0.423, 0.759) to day 5 (HR: 0.524, 95% C.I. 0.175, 0.576) were predictors of mortality. Neutrophil count was not a risk factor, but day 3 lymphocyte count (HR: 0.131, 95% C.I. 0.026, 0.646) and day 10 monocyte count (HR: 0.044, 95% C.I. 0.005, 0.396) were risk factors. Low platelet counts from day 3 (HR: 0.545, 95% C.I. 0.300, 0.981) to day 30 following injury were always a predictor of mortality.

CONCLUSIONS

Early thrombopenia and lymphopenia were independent risk factors for 60-day mortality, and prolonged thrombopenia and monocytopenia were independent risk factors for mortality. These findings might shed light on mechanisms of immune response following severe burns.

The Dynamics of the Skin's Immune System

The skin is a complex organ that has devised numerous strategies, such as physical, chemical, and microbiological barriers, to protect the host from external insults. In addition, the skin contains an intricate network of immune cells resident to the tissue, crucial for host defense as well as tissue homeostasis. In the event of an insult, the skin-resident immune cells are crucial not only for prevention of infection but also for tissue reconstruction. Deregulation of immune responses often leads to impaired healing and poor tissue restoration and function. In this review, we will discuss the defensive components of the skin and focus on the function of skin-resident immune cells in homeostasis and their role in wound healing.