Effect of Deferoxamine on Post-Transfusion Iron, Inflammation, and In Vitro Microbial Growth in a Canine Hemorrhagic Shock Model: A Randomized Controlled Blinded Pilot Study.

Red blood cell (RBC) transfusion is associated with recipient inflammation and infection, which may be triggered by excessive circulating iron. Iron chelation following transfusion may reduce these risks. The aim of this study was to evaluate the effect of deferoxamine on circulating iron and inflammation biomarkers over time and in vitro growth of Escherichia coli (E. coli) following RBC transfusion in dogs with atraumatic hemorrhage. Anesthetized dogs were subject to atraumatic hemorrhage and transfusion of RBCs, then randomized to receive either deferoxamine or saline placebo of equivalent volume (n = 10 per group) in a blinded fashion. Blood was sampled before hemorrhage and then 2, 4, and 6 h later. Following hemorrhage and RBC transfusion, free iron increased in all dogs over time (both p < 0.001). Inflammation biomarkers interleukin-6 (IL6), CXC motif chemokine-8 (CXCL8), interleukin-10 (IL10), and keratinocyte-derived chemokine (KC) increased in all dogs over time (all p < 0.001). Logarithmic growth of E. coli clones within blood collected 6 h post-transfusion was not different between groups. Only total iron-binding capacity was different between groups over time, being significantly increased in the deferoxamine group at 2 and 4 h post-transfusion (both p < 0.001). In summary, while free iron and inflammation biomarkers increased post-RBC transfusion, deferoxamine administration did not impact circulating free iron, inflammation biomarkers, or in vitro growth of E. coli when compared with placebo.

Effect of leukoreduction on inflammation in critically ill dogs receiving red blood cell transfusions: A randomized blinded controlled clinical trial.

BACKGROUND: Prestorage leukoreduction of red blood cell (RBC) bags prevents accumulation of pro-inflammatory mediators and experimentally attenuates post-transfusion inflammation in healthy dogs. However, the effect of leukoreduction on post-transfusion inflammation in critically ill dogs is unclear. HYPOTHESIS: Dogs transfused with leukoreduced (LR) RBC will have lower concentrations of leukocytes, interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), and C-reactive protein (CRP) within 24 hours of post-transfusion compared to dogs transfused with nonleukoreduced (NLR) RBC. ANIMALS: Sixty-one RBC-transfused dogs (LR = 34, NLR = 27). METHODS: Randomized, blinded, controlled preliminary clinical trial. Blood bag processing was randomized to create identically appearing LR and NLR bags. Group allocation occurred with transfusion of the oldest compatible RBC bag. Blood samples were collected pretransfusion and at 8 and 24 hours post-transfusion for leukocyte count, IL-6, IL-8, MCP-1, and CRP. Data were analyzed on an intention-to-treat basis using linear mixed effects models. Significance was set at P < .05. RESULTS: No significant differences were found between groups in concentrations of leukocytes (P = .93), IL-6 (P = .99), IL-8 (P = .75), MCP-1 (P = .69), or CRP (P = .18) over time. Eleven LR dogs (32%) and 4 NLR dogs (15%) were euthanized in the hospital (P = .14). No natural deaths occurred. CONCLUSIONS AND CLINICAL IMPORTANCE: No differences in inflammation biomarker concentrations were detected over time between dogs transfused with LR or NLR RBC, but heterogeneity likely hampered the ability to detect a difference with this sample size. The novel randomization and enrollment protocol was successfully implemented across 2 participating institutions and will be easily scaled up for a future multicenter clinical trial.

No association between intravenous fluid volume and endothelial glycocalyx shedding in patients undergoing resuscitation for sepsis in the emergency department.

Endothelial glycocalyx (EG) shedding is associated with septic shock and described following intravenous (IV) fluid administration. To investigate the possible impact of IV fluids on the pathobiology of septic shock we investigated associations between biomarkers of EG shedding and endothelial cell activation, and relationships with IV fluid volume. Serum samples were obtained on admission (T0) and at 24 h (T24) in patients undergoing haemodynamic resuscitation for suspected septic shock in the emergency department. Biomarkers of EG shedding-Syndecan-1 (Syn-1), Syndecan-4 (Syn-4), Hyaluronan, endothelial activation-Endothelin-1 (ET-1), Angiopoeitin-2 (Ang-2), Vascular Endothelial Growth Factor Receptor-1(VEGF-1) and leucocyte activation/inflammation-Resistin, Neutrophil Gelatinase Associated Lipocalin (NGAL) and a marker of cardiac stretch-Pro-Atrial Natriuretic Peptide (Pro-ANP) were compared to the total IV fluid volume administered using Tobit regression. Data on 86 patients (52 male) with a mean age of 60 (SD 18) years were included. The mean fluid volume administered to T24 was 4038 ml (SD 2507 ml). No significant association between fluid volume and Pro-ANP or any of the biomarkers were observed. Syn-1 and Syn-4 were significantly correlated with each other (Spearman Rho 0.43, p < 0.001) but not with Hyaluronan. Syn-1 and Syn-4 both correlated with VEGFR-1 (Rho 0.56 and 0.57 respectively, p < 0.001) whereas Hyaluronan correlated with ET-1 (Rho 0.43, p < 0.001) and Ang-2 (Rho 0.43, p < 0.001). There was no correlation between Pro-ANP and any of the EG biomarkers. Distinct patterns of association between biomarkers of EG shedding and endothelial cell activation were observed among patients undergoing resuscitation for sepsis. No relationship between IV fluid volume and Pro-ANP or any of the other biomarkers was observed.

A randomised controlled trial of succinylated gelatin (4%) fluid on urinary acute kidney injury biomarkers in cardiac surgical patients.

BACKGROUND: Fluid resuscitation is frequently required for cardiac surgical patients admitted to the intensive care unit. The ideal fluid of choice in regard to efficacy and safety remains uncertain. Compared with crystalloid fluid, colloid fluid may result in less positive fluid balance. However, some synthetic colloids are associated with increased risk of acute kidney injury (AKI). This study compared the effects of succinylated gelatin (4%) (GEL) with compound sodium lactate (CSL) on urinary AKI biomarkers in patients after cardiac surgery. METHODS: Cardiac surgical patients who required an intravenous fluid bolus of at least 500 mL postoperatively were randomly allocated to receive GEL or CSL as the resuscitation fluid of choice for the subsequent 24 h. Primary outcomes were serial urinary neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C concentrations measured at baseline, 1 h, 5 h and 24 h after enrolment, with higher concentrations indicating greater kidney injury. Secondary biomarker outcomes included urinary clusterin, α1-microglobulin and F2-isoprostanes concentrations. Differences in change of biomarker concentration between the two groups over time were compared with mixed-effects regression models. Statistical significance was set at P < 0.05. RESULTS: Forty cardiac surgical patients (n = 20 per group) with similar baseline characteristics were included. There was no significant difference in the median volume of fluid boluses administered over 24 h between the GEL (1250 mL, Q1-Q3 500-1750) and CSL group (1000 mL, Q1-Q3 500-1375) (P = 0.42). There was a significantly greater increase in urinary cystatin C (P < 0.001), clusterin (P < 0.001), α1-microglobulin (P < 0.001) and F2-isoprostanes (P = 0.020) concentrations over time in the GEL group, compared to the CSL group. Change in urinary NGAL concentration (P = 0.68) over time was not significantly different between the groups. The results were not modified by adjustment for either urinary osmolality or EuroSCORE II predicted risk of mortality. CONCLUSIONS: This preliminary randomised controlled trial showed that use of succinylated gelatin (4%) for fluid resuscitation after cardiac surgery was associated with increased biomarker concentrations of renal tubular injury and dysfunction, compared to crystalloid fluid. These results generate concern that use of intravenous gelatin fluid may contribute to clinically relevant postoperative AKI. Trial registration ANZCTR.org.au, ACTRN12617001461381. Registered on 16th October, 2017, http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=373619&isReview=true .

Prospective randomized controlled blinded clinical trial evaluating biomarkers of acute kidney injury following 6% hydroxyethyl starch 130/0.4 or Hartmann's solution in dogs.

OBJECTIVE: To evaluate the effect of 6% hydroxyethyl starch (HES) 130/0.4, compared with a Hartmann's solution control (CRYST), on urine biomarkers of acute kidney injury (AKI) in dogs prescribed a fluid bolus. DESIGN: Randomized, controlled, blinded clinical trial January 2018 to February 2019. SETTING: University teaching hospital. ANIMALS: Forty client-owned dogs. INTERVENTIONS: Dogs prescribed a fluid bolus were randomized to receive at least 10 mL/kg of HES or CRYST with clinicians and investigators blinded to fluid type. Study fluid was used for further boluses as required in the following 24 hours, to a limit of 40 mL/kg total, after which fluid administration was open-label. MEASUREMENTS AND MAIN RESULTS: Urine was collected prior to and 6, 12, and 24 hours after the first study fluid bolus. Urine concentrations of AKI biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), cystatin C, kidney injury molecule-1 (KIM), clusterin, and osteopontin were measured using a magnetic bead multiplexed assay. Osmolality-indexed biomarker concentrations were compared between groups over time with linear mixed-effects models, with P < 0.05 considered significant. The mean volume of study fluid administered was not significantly different between groups (HES: 23.1 mL/kg, CRYST: 25.9 mL/kg; P = 0.47, t-test). There were no significant differences between groups in change over time of osmolality-indexed urine concentrations of NGAL (P = 0.91), cystatin C (P = 0.95), KIM (P = 0.77), clusterin (P = 0.63), or osteopontin (P = 0.91). The maximum Veterinary Acute Kidney Injury (VAKI) score up to 7 days during hospitalization (P = 1.0) and in-hospital mortality (P = 0.49) were not significantly different between groups, as compared by Fisher's exact test. CONCLUSIONS: There were no differences in change over time of urine AKI biomarkers in dogs treated with 10 - 40 mL/kg HES or CRYST over 24 hours. Larger clinical trials with patient-centered outcomes are required to investigate the safety of HES in dogs.

Identification of The Canidae Iron Regulatory Hormone Hepcidin.

Hepcidins are an evolutionarily conserved class of liver-expressed peptide, from which the twenty-five amino acid hormone, hepcidin-25 (herein hepcidin), has gained significant notoriety as the master regulator of iron homeostasis in mammals. Hepcidin maintains iron homeostasis by controlling the dietary absorption of iron and the mechanisms of recycling cellular iron stores. With the physiological significance of this hormone well established, it has emerged as an informative biomarker. In a comparison of the genome, transcriptome and peptidome of Canis lupis familiaris, we reveal the size of the hepcidin peptide in the canine, previous reports of which were contradictory to the evolutionary conservation predicted by genome annotation. Here, measurement of the peptide by mass spectrometry, following isolation from greyhound blood serum, revealed an amino acid sequence and peptide mass, differing from all accounts to date, yet demonstrating perfect sequence identity to that of the greater Canidae lineage of the Carnivora. Importantly, in the greyhound, the measured hepcidin peptide showed a similar temporal pattern to total serum iron, consistent with our understanding of hepcidin regulating iron homeostasis, in agreement with human diagnostics, and providing added translational evidence of the measured peptide being the iron regulatory hormone of the Canidae.

Evaluation of biomarkers of kidney injury following 4% succinylated gelatin and 6% hydroxyethyl starch 130/0.4 administration in a canine hemorrhagic shock model.

OBJECTIVE: To investigate the association between synthetic colloids and biomarkers of acute kidney injury (AKI) in dogs with hemorrhagic shock. DESIGN: Experimental interventional study. SETTING: University. ANIMALS: Twenty-four healthy ex-racing Greyhounds. INTERVENTIONS: Anesthetized Greyhounds subjected to hemorrhage for 60 min were resuscitated with 20 mL/kg of fresh whole blood (FWB), 6% hydroxyethyl starch (HES) 130/0.4, 4% succinylated gelatin (GELO), or 80 mL/kg of isotonic crystalloid (CRYST) over 20 min (n = 6 per treatment). Concentrations of biomarkers of AKI were measured at baseline, end of hemorrhage, and at 40 (T60), 100 (T120), and 160 (T180) min after fluid bolus. Biomarkers included neutrophil gelatinase-associated lipocalin in urine and serum (uNGAL; sNGAL), and urine cystatin C (uCYSC), kidney injury molecule-1 (uKIM), clusterin (uCLUST), osteopontin, gamma-glutamyl transferase, monocyte chemoattractant protein-1 (uMCP), interleukin-6, interleukin-8, protein (uPROT), hyaluronan, and F2 -isoprostanes. Renal histology was scored for tubular injury and microvesiculation. Biomarker fold-change from baseline was compared between groups using mixed effects models (Bonferroni-Holm corrected P<0.05). Frequencies of histology scores were compared by Fisher's exact test. MEASUREMENTS AND MAIN RESULTS: In dogs treated with GELO, uNGAL fold-change was markedly greater compared with all other groups at T60, T120, and T180 (all P<0.001), and uCYSC was greater at T60 compared with CRYST (P<0.001), and at T120 and T180 compared with all other groups (all P<0.001). Smaller, albeit significant, between-group differences in uKIM, uCLUST, uMCP, and urine protein concentration were observed across the FWB, GELO, and HES groups, compared with CRYST. The GELO group more frequently had marked tubular microvesiculation than the other groups (P = 0.015) although tubular injury scores were comparable. CONCLUSION: In dogs with hemorrhagic shock, GELO was associated with greater magnitude increases in urine biomarkers of AKI and more frequent marked tubular microvesiculation, compared with FWB, CRYST, and HES.

Glycocalyx biomarker syndecan-1 is a stronger predictor of respiratory failure in patients with sepsis due to pneumonia, compared to endocan.

PURPOSE: Endocan, a component of the endothelial glycocalyx (EG), has been linked with respiratory failure in sepsis. This study explored the temporal patterns of three EG biomarkers, including endocan, and their relationships with inflammation and respiratory failure. MATERIALS AND METHODS: Plasma endocan, syndecan-1, and hyaluronan concentrations were measured in Emergency Department (ED) patients with sepsis due to pneumonia (n = 44) on ED arrival (T0), 1 h (T1), 3 h (T3) and 12-24 h (T24) later, with change over time tested using mixed regression models. Biomarker associations with inflammatory cytokine concentrations and with respiratory failure on days 1, 2 or 3, need for mechanical ventilation and 30-day mortality were also tested. RESULTS: Endocan concentration significantly decreased over time (T0-T24, P = 0.003) whereas both syndecan-1 (T0-T3, P = 0.010; T0-T24, P < 0.001) and hyaluronan (T0-T1, P = 0.010; T0-T3, P < 0.001; T0-T24, P = 0.003) significantly increased over time. Increased syndecan-1 was significantly correlated with neutrophil activation biomarkers and significantly increased the odds of respiratory failure (OR 1.18, 95% CI 1.05-1.33, P = 0.004), need for mechanical ventilation (OR 1.24, 95% CI 1.04-1.48, P = 0.014) and 30-day mortality (OR 1.29, 95% CI 1.07-1.55, P = 0.008). CONCLUSION: Syndecan-1, but not endocan, was associated with neutrophil activation and was the best EG biomarker predictor of adverse clinical outcomes.

Large-Volume Crystalloid Fluid Is Associated with Increased Hyaluronan Shedding and Inflammation in a Canine Hemorrhagic Shock Model.

Shedding of the endothelial glycocalyx precedes leukocyte activation and adherence in acute inflammation. Rapid administration of crystalloid or colloid fluids for treating hemorrhagic shock may cause endothelial glycocalyx shedding, thereby increasing inflammation. This study aimed to compare the effect of different fluid treatments in a canine shock model on glycocalyx biomarker, hyaluronan, and inflammatory biomarkers. Greyhound dogs under general anesthesia subject to hemorrhage for 60 min were given 20 mL kg-1 of either fresh whole blood (FWB), hydroxyethyl starch (HES) 130/0.4, 4% succinylated gelatin (GELO), or 80 mL kg-1 of isotonic crystalloid (CRYST) over 20 min (n = 6 per group). Plasma biomarkers hyaluronan, interleukin (IL) 6, 8, 10, tumor necrosis factor-α, monocyte chemoattractant protein-1, keratinocyte chemokine-like, and atrial natriuretic peptide were measured at baseline, end of hemorrhage (Shock), end of fluid administration (T20), and then 40 (T60), 100 (T120), and 160 (T180) minutes later. Biomarker concentrations were compared between groups using the Kruskal-Wallis test or Fisher's exact test (measurable versus unmeasurable) (significance set at P < 0.05). Hyaluronan concentration peaked early in the CRYST group at T20, compared to HES (P = 0.005) and GELO (P = 0.018), and later in the GELO group at T60, compared to FWB (P < 0.001). The CRYST group had significantly more samples with measurable IL6 at T180 (P = 0.015), compared to GELO, and IL10 at T60, T120, and T180 (all P = 0.015), compared to FWB. There were no significant differences in other biomarker concentrations. In conclusion, rapid large-volume crystalloid administered for hemorrhagic shock was associated with increased hyaluronan and a greater inflammatory response.

Resistin and NGAL are associated with inflammatory response, endothelial activation and clinical outcomes in sepsis.

OBJECTIVE AND DESIGN: Resistin and neutrophil gelatinase-associated lipocalin (NGAL) are upregulated in circulating leucocytes in sepsis, but the significance of this is uncertain. We evaluated associations between Resistin and NGAL with endothelial cell activation and clinical outcomes in a prospective observational study in the Emergency Department (ED). METHODS: Serum levels of Resistin, NGAL, inflammatory cytokines (IL-6, IL-10) and soluble endothelial adhesion molecules (VCAM-1, ICAM-1) were measured at defined time points up to 24 h. Patterns and relationships between markers were investigated using linear mixed regression models. Predictive values for clinical outcomes for markers at enrollment were assessed by logistic regression and receiver operator characteristic (ROC) curves. RESULTS: 186 participants (89 septic-shock, 69 sepsis, 28 uncomplicated infection) were compared with 29 healthy controls. Median Resistin and NGAL were higher in uncomplicated infection compared to controls, and in septic shock compared to non-shock sepsis. Resistin and NGAL correlated with IL-6 and IL-10, with VCAM-1 and ICAM-1, and with organ failure. Resistin and NGAL were associated with septic shock but had limited predictive utility for mortality. CONCLUSION: Resistin and NGAL correlate with expression of endothelial cell adhesion molecules in sepsis. Further evaluation of the role of Resistin and NGAL in sepsis pathogenesis is warranted.

Platelet closure time in anesthetized Greyhounds with hemorrhagic shock treated with hydroxyethyl starch 130/0.4 or 0.9% sodium chloride infusions.

OBJECTIVE: To measure platelet closure time (PCT) in dogs during controlled hemorrhagic shock and after fluid resuscitation with hydroxyethyl starch (HES) 130/0.4 or 0.9% sodium chloride. DESIGN: Experimental interventional study. SETTING: University veterinary teaching hospital. ANIMALS: Eleven healthy Greyhounds. INTERVENTIONS: Dogs were anesthetized and had 48 mL/kg of blood removed to induce hemorrhagic shock. Dogs received 20 mL/kg of HES 130/0.4 (n = 6) or 80 mL/kg of 0.9% sodium chloride (NaCl; n = 5) intravenously over 20 minutes. PCT was measured using the Platelet Function Analyzer-100 with collagen and adenosine-diphosphate cartridges at: T0 = 60 minutes after induction of anesthesia prior to hemorrhage, T1 = during hemorrhagic shock, and T2 = 40 minutes after completion of fluid bolus. Packed cell volume and platelet count were concurrently measured. MEASUREMENT AND MAIN RESULTS: Hemorrhagic shock did not significantly change PCT, with no difference between T0 and T1. Both the HES 130/0.4 and 0.9% NaCl group had a significantly increased mean PCT at T2 of 91.4 seconds (95% CI 69.3-113.4) and 95.5 seconds (95% CI 78.2-112.8), respectively, compared to T1. The magnitude of change was significantly greater for the 0.9% NaCl group than the HES 130/0.4 group. There was no difference in the magnitude of change in PCV and platelet count between the 2 groups. The PCV and platelet count were >25% and >100,000/µL, respectively, in all dogs, except for dogs in the HES 130/0.4 group at T2 where platelet counts were <100,000/µL. CONCLUSION: Controlled hemorrhagic shock in Greyhounds under anesthesia did not cause a significant change in PCT. Both HES 130/0.4 and 0.9% NaCl administration after induction of shock increased PCT. These results do not support that HES 130/0.4 causes relevant platelet dysfunction beyond hemodilution.

Effect of leukoreduction on concentrations of interleukin-8, interleukin-1ß, and tumor necrosis factor-α in canine packed red blood cells during storage.

OBJECTIVE To measure changes in interleukin-8 (IL-8), interleukin-1ß (IL-1ß), and tumor necrosis factor-α (TNF-α) concentrations in stored canine packed RBCs (PRBCs) over time and assess the effect of leukoreduction on these cytokine concentrations. ANIMALS 12 anesthetized healthy Greyhounds. PROCEDURES 1 unit of whole blood from each dog was processed into PRBCs. Half of each PRBCs unit was passed through a leukoreduction filter to produce a leukoreduced unit, and the remaining blood was kept as a nonleukoreduced unit. All units had a CBC performed on day 0 (day of collection) and were stored at 2° to 6°C. Samples were collected from leukoreduced and nonleukoreduced units on days 0, 10, 20, 30, and 37 and centrifuged; the supernatant was stored at -80°C until analysis. Canine TNF-α and IL-8 concentrations were assessed with a multiplexed genomic and proteomic biomarker analyzer, and canine IL-1ß concentration was measured by ELISA. RESULTS Leukocyte counts were decreased by ≥ 99.9% in all leukoreduced units. Median TNF-α and IL-1ß concentrations were not significantly different between leukoreduced and nonleukoreduced units and did not change significantly during storage; median IL-8 concentration was significantly higher in nonleukoreduced versus leukoreduced units on all days, and was greater at all time points after ≥ 10 days of storage than on day 0. Median IL-8 concentration in leukoreduced units did not increase during storage. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that leukoreduction was effective for the removal of leukocytes from canine PRBCs and prevented significant increases in IL-8 concentration during storage. Further studies are needed to evaluate whether leukoreduction reduces cytokine-associated complications of transfusion.

Cardiovascular function during maintenance of anaesthesia with isoflurane or alfaxalone infusion in greyhounds experiencing blood loss.

OBJECTIVE: To compare adequacy of oxygen delivery and severity of shock during maintenance of anaesthesia with isoflurane or alfaxalone infusion in greyhounds experiencing blood loss. STUDY DESIGN: Prospective, randomised study. ANIMALS: Twenty-four greyhounds (ASA I). METHODS: All greyhounds were premedicated with methadone (0.2 mg kg(-1) ) intramuscularly. Anaesthesia was induced with alfaxalone 2.5 mg kg(-1) intravenously. Following endotracheal intubation, the dogs were connected to an anaesthetic circle circuit delivering oxygen. Dogs were allocated to receive inhaled isoflurane or an intravenous infusion of alfaxalone for maintenance of anaesthesia. Isoflurane was initially administered to achieve an end-tidal concentration of 1.4% and alfaxalone was initially administered at 0.13 mg kg(-1)  minute(-1) . The dose of isoflurane or alfaxalone was adjusted during instrumentation to produce a clinically equivalent depth of anaesthesia. All dogs were mechanically ventilated to normocapnia (Pa CO2 35-40 mmHg; 4.67-5.33 kPa). Passive warming maintained core body temperature between 37 and 38 °C. Measured and calculated indices of cardiovascular function, including mean arterial blood pressure (MAP), cardiac index (CI), systemic vascular resistance index (SVRI), oxygen delivery index (D˙O2I), oxygen consumption index (V˙O2I) and oxygen extraction ratio (OER), were determined at baseline (60 minutes after start of anaesthesia) and after removal of 32 mL kg(-1) and 48 mL kg(-1) of blood. RESULTS: In all dogs, blood loss resulted in a significant decrease in MAP, CI, D˙O2 , and a significant increase in SVRI, V˙O2I , and OER. The changes in each of the indices did not differ significantly between dogs receiving isoflurane and dogs receiving alfaxalone. CONCLUSION AND CLINICAL RELEVANCE: No difference in oxygen delivery or severity of shock was observed when either inhaled isoflurane or intravenous alfaxalone infusion was used for maintenance of anaesthesia in greyhounds experiencing blood loss. There appears to be no clinical advantage to choosing one anaesthetic agent for maintenance of anaesthesia over the other in a dog experiencing blood loss.