Dose-dependent effect of canine lyophilized platelet on an in vitro hemodilution model.

The transfusion of stored platelets has emerged as an efficient method for treating dogs with thrombocytopenia. However, the availability of fresh platelets is limited in veterinary medicine due to demanding storage conditions. Lyophilized platelets have long shelf lives and can be easily stored, increasing their accessibility for thrombocytopenic dogs. Due to the lack of research and information on the dose effect, canine lyophilized platelets are used at a clinical dosage without research-based evidence. This study was to evaluate the dose effect of lyophilized canine platelets on blood coagulability. Three different concentrations of lyophilized canine platelets were added to in vitro hemodilution blood model, increasing the platelet count by 25, 50, and 100 × 106/ml and coagulation profiles were analyzed. The coagulability was evaluated via the plasma fibrinogen concentration, coagulation time, thromboelastography (TEG), and platelet function analyzer (PFA). Higher concentrations of lyophilized platelets showed dose-dependent association with decreased aPTT and R-time of TEG and increased alpha angle and MA of TEG. These results showed the potential that the higher dose of canine lyophilized platelets better improve blood coagulability than the standard dose and provided the basis for further safety and clinical studies.

Acute Normovolemic Hemodilution-assisted Terminal Blood Procurement in Swine for Ex Vivo Organ Perfusion.

Swine (Sus scrofa domesticus) are commonly used large animal subjects for the study of disease and preclinical therapies. Organ machine perfusion is a therapy that has gained momentum as a research platform for the study of ex vivo organ preservation and therapeutics. However, complex perfusion circuits and research protocols often require large volumes of blood as perfusate. Here, we report a technique for increasing terminal blood yield during swine organ and blood procurement; our method involves acute normovolemic hemodilution and exsanguination via the femoral artery. We collected a total of 47 ± 4 mL/kg of blood and 4.3 ± 0.6 g/kg of hemoglobin, representing 73% ± 6% of the estimated blood volume and 64% ± 8% of the total estimated intravascular hemoglobin (n = 4). Neither pH, lactate, nor pO2 levels changed significantly during blood procurement. Acute normovolemic hemodilution is an effective method for increasing RBC and hemoglobin yield during blood procurement in swine.

Continuous fluid infusion per rectum compared with intravenous and nasogastric fluid administration in horses.

BACKGROUND: Rectal fluid administration may offer a simple, safe and inexpensive alternative to intravenous or nasogastric fluid therapy in equine clinical cases. OBJECTIVES: To evaluate the tolerance and effects of rectally administered fluid and compare the measurements of haemodilution and intravascular volume with those during nasogastric and intravenous fluid administration. STUDY DESIGN: Randomised controlled experimental trial. METHODS: Six clinically normal Standardbred geldings were used in a 4-way crossover study: each received three different fluid treatments (intravenous, nasogastric and rectal) at 5 mL/kg/h for 6 h and underwent a control (no treatment) with water and feed withheld. Bodyweight was measured at baseline and 6 h. Packed cell volume (PCV), total solids (TS), albumin, electrolytes, lactate, urine specific gravity, vital parameters, gastrointestinal borborygmi and central venous pressure were measured every 2 h. RESULTS: Rectal fluid administration with plain water was well tolerated and caused clinical chemistry changes consistent with haemodilution, indicating absorption. Mean (95% confidence interval) PCV decreased from 40% [40-42] at 0 h to 35% [34-36] at 6 h during rectal fluid treatment (P<0.001), similar to decreases in PCV occurring also with i.v. and nasogastric (NGT) treatment (P<0.001). The TS also decreased with i.v. and rectal fluid (P<0.001). There was a decrease in bodyweight in the control (P<0.001) but not with any of the fluid treatments. MAIN LIMITATIONS: A small sample size of healthy, euhydrated horses and a relatively short duration of fluid administration was used. CONCLUSIONS: Rectal fluid administration requires clinical evaluation, but may offer an inexpensive, safe alternative or adjunct to i.v. fluid administration, particularly when administration via NGT is not possible or contraindicated. The Summary is available in Portuguese - see Supporting Information.

Efeito da fluidoterapia transcirúrgica sobre o hematócrito pós-cirúrgico em cadelas submetidas a ovariossalpingo-histerectomia eletiva / Effects of trans surgical fluid therapy over the post surgical packed cell volume in bitches undergoing elective ovariohisterectomy

Apesar dos inúmeros benefícios da fluidoterapia transcirúrgica, sobrecarga de volume pode trazer efeitos deletérios, como a alteração de parâmetros hematimétricos. Dessa maneira, o presente trabalho teve como objetivo avaliar duas diferentes taxas de infusão de solução cristaloide no período transanestésico e seus efeitos até 24 horas pós-operatório. Foram utilizados dois grupos de seis animais cada, um deles recebeu solução de cloreto de sódio 0,9% a 10mL/kg/h (G10) e o outro a 5mL/kg/h (G5). Os valores de hematócrito foram avaliados no período de 24 horas em 10 diferentes momentos. Os resultados não apontaram diferenças significativas entre os grupos, porém foi observada redução significativa do hematócrito após indução anestésica. Foi ainda observada redução de hematócrito após o término da cirurgia em ambos os grupos, e o retorno aos valores basais de hematócrito ocorreu de forma significativa 12 horas após o procedimento cirúrgico em G10, e após oito horas em G5, mostrando uma tendência à hemodiluição mais persistente em G10.(AU)

Despite the beneficial goals of fluid therapy administered during surgery, volume overload can cause deleterious effects, such as alterations on hematimetric parameters. Thus, the objective of this paper was to evaluate two different cristaloid infusion rates during the surgical period and its effects on the 24-hour post-surgical period. Two groups of six animals each were used in the present study, one received 10mL/kg/h (G10) of 0,9% sodium chloride solution and the other 5mL/kg/h (G5) of the same solution. Packed cell volume (PCV) was evaluated in 10 different times during the 24 hours following surgery. The results did not show significant differences between groups, but they showed a major tendency of hemodilution in G10. A significant decrease of PCV was observed after induction of anesthesia. Decrease of PCV after the end of surgery in both groups was also observed, and the return to PCV basal values was observed 12 hours after the procedure in G10 and after eight hours in G5, showing a tendency of prolonged hemodilution in G10.(AU)

Effects of in vitro hemodilution with crystalloids, colloids, and plasma on canine whole blood coagulation as determined by kaolin-activated thromboelastography.

OBJECTIVE: To investigate the effects of in vitro hemodilution with lactated Ringers solution (LRS), hetastarch (HES), and fresh frozen plasma (FFP) on whole blood coagulation in dogs as assessed by kaolin-activated thromboelastography. DESIGN: In vitro experimental study. SETTING: University teaching hospital. ANIMALS: Six healthy client-owned dogs. INTERVENTIONS: Whole blood was collected and diluted in vitro at a 33% and 67% dilution with either LRS, HES, or FFP. MEASUREMENTS AND MAIN RESULTS: Kaolin-activated thromboelastography was performed on each sample as well as a control. Thromboelastographic parameters R (min), alpha (deg), K (min), and MA (mm) were measured and compared to the sample control for each dilution using mixed model methodology. Prolongation in coagulation times were seen at both dilutions with LRS and HES. There was no significant difference in R times at the 33% dilution, but R time was significantly prolonged at the 67% dilution with HES (P = 0.004). MA was significantly decreased for LRS at both dilutions (P = 0.013, P < 0.001) and more profoundly decreased for HES (P < 0.001, P = 0.006). No significant difference in any parameter was found for FFP. CONCLUSIONS: In vitro hemodilution of whole blood with both LRS and HES but not FFP resulted in significant effects on coagulation with HES having a more profound effect. In vivo evaluation of changes in coagulation with various resuscitation fluids is warranted and may be clinically relevant.

In vitro evaluation of canine hemostasis following dilution with hydroxyethyl starch (130/0.4) via thromboelastometry.

OBJECTIVE: To assess the effects of in vitro hemodilution of canine blood with a low molecular weight hy-droxyethyl starch (HES 130/0.4) by means of thromboelastometry (TEM). DESIGN: In vitro experimental study. SETTING: University Teaching Hospital. ANIMALS: Ten healthy adult staff-owned dogs were sampled for the purposes of the study. Samples were also collected from 45 clinically normal dogs to establish thromboelastometric reference intervals. INTERVENTIONS: For each dog whole blood was collected by jugular venipuncture and placed into tubes containing 3.8% trisodium citrate and stored at 37°C. Two standard dilutions (1:4 and 1:10) from canine blood specimens were prepared with HES 130/0.4 and saline 0.9%. MEASUREMENTS AND MAIN RESULTS: The effects of dilution were studied by TEM. No statistically significant differences were observed between the TEM values of the control samples and the samples diluted with saline solution (ratio 1:10 and 1:4). In contrast, hypocoagulability was observed in the samples treated with HES 130/0.4, with more severe effects at 1:4 dilution than at 1:10 dilution. The 1:4 dilution with HES 130/0.4 produced marked alterations: CT (P = 0.035) and CFT (P = 0.0007) on the ex-TEM profile, CT (P = 0.0005) and ML (P = 0.0017) on the fib-TEM profile and CFT (P = 0.0043) on the in-TEM, were all significantly increased (P < 0.05), whereas MCF (P = 0.0042) and alpha angle (P = 0.002) on the in-TEM and MCF (P = 0.011) and alpha angle (P = 0.001) ex-TEM profiles and MCF (P = 0.0001) on the fib-TEM profile were significantly decreased (P < 0.05). CONCLUSIONS: Dilution of canine blood with HES 130/0.4 results in a thromboelastometric pattern consistent with hypocoagulation and this effect appears to result from a dose-dependent alteration in fibrinogen concentration and inhibition of platelet function. As this is an in vitro study, further in vivo investigations are necessary to confirm the results.

Effects of in vitro hemodilution of canine blood on platelet function analysis using the PFA-100.

BACKGROUND: The platelet function analyzer (PFA)-100 is a point-of-care instrument previously evaluated in humans and dogs. In both species, artificially prolonged platelet closure time (CT) occurs with anemia. Reliability of the analyzer in dogs becomes a concern when the HCT is between 0.25 and 0.35 L/L. OBJECTIVE: The objective of this study was to further define the level of HCT at which CT is prolonged, using in vitro diluted canine blood. METHODS: Citrated whole blood samples were collected from 22 healthy dogs. Initial HCT was determined and autologous platelet-rich plasma was added to samples to achieve HCTs of 0.33, 0.30, and 0.27 L/L. CT was determined in duplicate on the PFA-100 using collagen/adenosine-5'-diphosphate cartridges. RESULTS: Compared with the initial CT in samples with HCT 0.39-0.54 L/L (CT mean+/-SD=57.8+/-5.75 seconds), significantly prolonged CTs were found in hemodiluted samples with HCT 0.33 L/L (61.1+/-4.64 seconds), 0.30 L/L (64.3+/-6.79 seconds), and 0.27 L/L (70.8+/-7.90 seconds) (P=0.029; repeated measures ANOVA). CONCLUSION: Although statistical differences were found, further studies are needed to determine the clinical significance of the mild prolongation in CT associated with mild anemia. Until then, dogs with HCTs slightly <0.35 L/L should be evaluated cautiously for platelet dysfunction using the PFA-100.

Acute normovolaemic haemodilution--2 case studies.

Acute normovolaemic haemodilution (ANH) is a technique used to preserve a patient's owns red blood cells and reduce the incidence of heterogeneous blood transfusion. This paper describes the use of the technique in a dog and a kitten. A significant benefit of ANH can be shown in the canine case presented. The dog lost 1800 ml of blood during surgery but the haematocrit was only reduced to 33% 6 hours after the end of surgery. The kitten, however, did not benefit from ANH. It lost a small volume of blood during surgery and developed complications. This paper also describes some of the potential complications that may occur. To the best of my knowledge, this is the 1st clinical description of ANH in a dog and a cat.

Acute normovolaemic haemodilution--is it a solution to reduce perioperative blood transfusions?

Haemodilution is a technique used to reduce perioperative homologous blood transfusions. Haemodilution is a poorly investigated technique in veterinary medicine. This article reviews haemodilution as a potential technique to reduce perioperative homologous blood transfusions. The history of haemodilution is briefly reviewed followed by the mathematical basis to haemodilution. The issue of critical oxygen delivery and its implications for haemodilution are discussed. The effects of haemodilution on the patient, including the effects on oxygen transport, blood flow and coagulation are discussed as well as the use of colloids, fluids and blood components in haemodilution. The success and failure of haemodilution in human clinical trials and experimental evidence is discussed. Some guidelines are given for the use of haemodilution in small animal patients in the perioperative setting. It appears in all likelihood that haemodilution has a limited application in cats and other small patients. Haemodilution is most beneficial when the initial haematocrit is high, a low haemodiluted haematocrit is achieved, the patients circulating volume is large and a large amount of blood was lost. It is important to avoid haemoconcentration during surgery as this increases red blood cell loss. Haemodilution is not a substitute for poor surgical technique and inadequate haemostasis intra-operatively. Intravascular volume should be maintained throughout the procedure.

Cardiopulmonary bypass influences the plasma levels of calcitonin gene-related peptides in dogs: effects of hemofiltration and hemodilution.

Calcitonin gene-related peptides (CGRP), which are potent vasodilators, are elevated during cardiopulmonary bypass (CPB) in humans. We evaluated the plasma levels of CGRP in dogs during CPB with hemofiltration with and without hemodilution. Female beagles were divided into control (n=5) and hemodilution (n=5) groups. The CPB with hemofiltration was performed with or without hemodilution. For the measurement of CGRP, blood samples were collected pre-CPB, during CPB, and post-CPB. The concentrations of CGRP in the hemofiltration solution were measured. Although the CPB elevated the plasma CGRP levels in both groups, its elevation was significant in the hemodilution group when compared to the pre-CPB levels. CGRP levels returned to normal post-CPB. Significant differences were found between the two groups in the CGRP amount in hemofiltration. The results show that hemofiltration should be used during CPB to decrease the plasma levels of CGRP.

Cardiovascular and pulmonary effects of hetastarch plus hypertonic saline solutions during experimental endotoxemia in anesthetized horses.

BACKGROUND: Small volume resuscitation has been advocated as a beneficial therapy for endotoxemia in horses but this therapy has not been investigated in a prospective manner. The objective of this study was to determine the cardiopulmonary effects of small-volume resuscitation using hypertonic saline solution (HSS) plus Hetastarch (HES) during experimental endotoxemia in anesthetized horses. HYPOTHESIS: Treatment of horses with induced endotoxemia using HES-HSS does not alter the response of various cardiopulmonary indices when compared to treatment with either small- or large-volume isotonic crystalloid solutions. ANIMALS: Eighteen healthy horses were randomly assigned to 1 of 3 groups. Anesthesia was maintained with halothane. Endotoxemia was induced by administering 50 microg/kg of Escherichia coli endotoxin IV. The horses were treated over 30 minutes with 15 mL/kg of balanced polyionic crystalloid solution (control), 60 mL/kg of balanced polyionic crystalloid solution (ISO), or 5 mL/kg of HSS followed by 10 mL/kg of HES (HSS-HES). METHODS: Prospective randomized trial. RESULTS: Cardiac output (CO) after endotoxin infusion increased significantly (P < .05) from baseline in all groups, whereas mean central venous pressure increased significantly (P < .05) in the ISO group only. Mean pulmonary artery pressure increased from baseline (P < .05) in horses treated with isotonic fluids and HSS-HES. There was no effect of treatment with HSS-HES on CO, systemic vascular resistance (SVR), mean arterial pressure, blood lactate concentrations, or arterial oxygenation. CONCLUSIONS AND CLINICAL IMPORTANCE: The use of HSS-HES failed to ameliorate the deleterious hemodynamic responses associated with endotoxemia in horses. The clinical value of this treatment in horses with endotoxemia remains unconfirmed.

Oncotic, hemodilutional, and hemostatic effects of isotonic saline and hydroxyethyl starch solutions in clinically normal ponies.

OBJECTIVE: To evaluate the oncotic, hemodilutional, and hemostatic effects of IV infusions of a large volume of isotonic saline solution and 2 doses of 6% hydroxyethyl starch (HES) in clinically normal ponies. ANIMALS: 12 adult ponies. PROCEDURE: Ponies were assigned to 3 treatment groups and received the following IV infusions: 80 ml of 0.9% sodium chloride/kg; 10 ml of 6% HES (in 0.9% sodium chloride)/kg; or 20 ml of 6% HES (in 0.9% sodium chloride)/kg. Blood samples were collected for determination of colloid oncotic pressure (COP), PCV, plasma total protein concentration, platelet count, von Willebrand factor antigen (vWf:Ag) activity, fibrinogen concentration, prothrombin time, activated partial thromboplastin time (APTT), and factor VIII coagulant (FVIII:C) activity. A rocket immunoelectrophoretic procedure was used for determination of vWf:Ag activity. A modification of the APTT assay was used for determination of FVIII:C activity. Cutaneous bleeding time was determined, using a template method. RESULTS: Mean COP was persistently increased over baseline values in the face of hemodilution in HES-treated ponies. Prothrombin time, APTT, and fibrinogen concentrations decreased after infusions and vWf:Ag and FVIII:C activities were decreased in dose-dependent manner in HES-treated ponies. Though cutaneous bleeding time was not significantly affected in ponies of any group, a trend toward prolongation of bleeding time was evident in ponies receiving 20 ml of HES/kg. This trend appeared to be associated with marked decrement in vWf:Ag activity at this dosage. CONCLUSIONS AND CLINICAL RELEVANCE: Infusion of HES in clinically normal ponies increases COP, and exerts dose-dependent hemodilutional effects and dose-dependent effects on specific hemostatic variables. Thus, HES may be useful for resuscitative fluid treatment of horses.

Cardiorespiratory effects of hemic versus nonhemic prime during and immediately following mitral valve replacement in dogs.

In order to limit the hemodilution effect during cardiopulmonary bypass (CPB) in low weight animal patients, blood is often used as a component of the prime solution. This study was undertaken to evaluate the effects of the addition of blood to the prime solution on the hemodynamic and respiratory parameters during and following mitral valve replacement in dogs. Ten dogs were randomly assigned to receive either a hemic (HP), 75% blood component, or a nonhemic prime (NP) solution. The hemodilution was 5 +/- 4% and 25 +/- 10% for the HP and NP groups, respectively. Cardiopulmonary measurements were taken 20 minutes before initiating CPB, during CPB, and 20 min after termination. The hematocrit level, the hemoglobin concentration, and the arterial oxygen content were significantly lower in the NP group during and following CPB. However, the systemic oxygen transport index was not significantly different between the NP group (355 +/- 87 mL/min/m2) and the HP group (546 +/- 155 mL/min/m2) following CPB. Our study indicates that, in normal dogs undergoing hemodilution from a nonhemic prime solution, the cardiovascular function is able to maintain the systemic oxygen transport in the period immediately following mitral valve replacement.

[Preliminary experiences with the treatment of shock in horses with a plasma expander from a starch base]. / Erste Erfahrungen bei der Schockbehandlung des Pferdes Mit Einem Plasmaexpander auf Stärkebasis.

HAES Steril 10% is a colloidal plasma expander rarely used in veterinary medicine. In this study HAES was used in clinical cases for the treatment of shock and in a comparative hypervolemic hemodilution study (HAES versus lactated Ringer's solution) using two experimental horses. Injection of a HAES volume equivalent to 10% of estimated blood volume resulted in a highly significant drop in PCV and in a significant drop in total protein concentration. Half live of HAES was approximately two hours. No incompatibility reactions were observed. In man HAES improves microcirculation. Studies in progress may confirm a similar effect in the equine.