Hydroxyethyl starch: a review of pharmacokinetics, pharmacodynamics, current products, and potential clinical risks, benefits, and use

Effects of Plasma and Hetastarch Administration on Colloid Oncotic Pressure and Coagulation Variables in Dairy Calves and Goats

BACKGROUND

Transfusion with fresh frozen plasma (FFP) or hetastarch 6% (HES) is an option for managing decreased colloid oncotic pressure (COP) associated with hypoproteinemia. The effectiveness of HES compared to plasma has not been reported in calves and goats.

HYPOTHESIS

Hetastarch increases COP to levels similar to FFP. There will be no significant adverse clinicopathological changes after administration of HES.

ANIMALS

Seven healthy preweaned calves and 7 juvenile goats from university herds.

METHODS

Cohort, clinical trial in a two-way crossover design. Hetastarch and FFP were administered intravenously at 10 and 20 mL/kg, respectively, once. Plasma COP was measured re-transfusion, at 0, 1, 2, 4, 6, 12, 24, 36, 72 h, and 7 days after each transfusion. Coagulation variables were analyzed pre-transfusion, at 0, 24, and 72 h after transfusion. The effects of treatment and time on COP and coagulation variables were determined by multivariate analysis of variance.

RESULTS

Transfusion with FFP and HES increased the COP in calves and goats, with FFP increasing the COP to a greater magnitude in calves (least square mean difference of 1.6 vs. 1 mmHg; p = 0.03) but not in goats (least square mean difference of 3.0 vs. 3.0 mmHg; p = 0.99). There were no significant changes (p > 0.05) in coagulation variables detected after transfusion with FFP or HES.

CONCLUSIONS AND CLINICAL IMPORTANCE

Hetastarch is an alternative colloid to FFP in calves and goats. Adverse changes were not observed in goats and calves after HES administration.

Effects of haemorrhage and lactated Ringer's solution or tetrastarch 130/0.4 resuscitation on colloidal osmotic pressure and osmolality in cats

ObjectivesTo determine the effects of haemorrhage and fluid over-resuscitation on colloidal osmotic pressure of albumin (COP albumin), plasma (Posm) and effective (Eosm) osmolality in anaesthetised cats.MethodsA total of six cats were given three treatments once, at 2-month intervals, in a randomised, crossover haemorrhage-resuscitation study. The treatments were divided into two phases, a controlled haemorrhage phase and a fluid resuscitation phase, as follows: (1) NoHR = no controlled haemorrhage and no resuscitation; (2) LRS = controlled haemorrhage followed by lactated Ringer's solution infusion (60 ml/kg/h); and (3) TS = controlled haemorrhage followed by 6% tetrastarch 130/0.4 suspended in 0.9% saline infusion (20 ml/kg/h). The resuscitation fluids were administered for 120 mins. Data were collected before haemorrhage, before resuscitation and at 30 min intervals until 120 mins. Variables were calculated at each time point as follows: COP albumin = albumin concentration (g/l) × 0.57; Posm = (2 × sodium) + glucose + blood urea nitrogen; and Eosm = (2 × sodium) + glucose. All Posm and Eosm concentrations were measured as mmol/l. Data were compared using a general linear mixed model (significance: P <0.05).ResultsMean ± SD total haemorrhage volumes for NoHR, LRS and TS were 10.2 ± 2.3, 29.3 ± 9.0 and 29.1 ± 6.3 ml/kg, respectively. The COP albumin decreased over time in all treatments regardless of volumes of blood lost and fluid administered. The decrease in COP albumin was profound and clinically relevant in LRS and TS (both P <0.001). There were no statistical differences in Posm and Eosm over time except in LRS at 90 (P = 0.004) and 120 ml/kg (P <0.001).Conclusions and relevanceThe COP albumin decreased in all treatments but to low and clinically relevant concentrations in LRS and TS, putting the cats at risk of fluid overload. There were no clinically relevant derangements in Posm and Eosm.

A review of carbohydrate polymer-synthesized nanoparticles in cancer immunotherapy: Past, present and future perspectives

Cancer continues to be a leading factor in mortality and tackling it has been made difficult by the development of immune escape. Furthermore, alternative treatments like surgery, chemotherapy, and radiation have been unsuccessful in eradicating cancer. Despite being effective, they have not succeeded in providing a full cancer treatment and exhibit several negative effects. The field of immunotherapy has been improved by utilizing cancer vaccines, immune checkpoint inhibitors (ICIs), and adoptive cell transfer to enhance immune responses to tumors. Nevertheless, cancer cells need to adapt and become immune to immune reactions, leading to the need for innovative treatment methods. Carbohydrate polymers and their nanoparticles have been beneficial in improving cancer immunotherapy by being customizable to specifically target the immune system. These nanoparticles can change the tumor microenvironment and accelerate immunotherapy by affecting immune cells such as T cells and dendritic cells. Incorporating both chemotherapy and phototherapy into nanoparticles can improve immunotherapy. Furthermore, besides controlling immune reactions, carbohydrate polymer nanoparticles can also be used for theranostic purposes, where they are used to image tumor cells and activate the immune system to eradicate cancer.

Strategies and Methodologies for Improving Toughness of Starch Films

Starch films have attracted increasing attention due to their biodegradability, edibility, and potential use as animal feed from post-products. Applications of starch-based films include food packaging, coating, and medicine capsules. However, a major drawback of starch-based films is their brittleness, particularly under dry conditions, caused by starch retrogradation and the instability of plasticizers. To address this challenge, various strategies and methodologies have been developed, including plasticization, chemical modification, and physical reinforcement. This review covers fundamental aspects, such as the microstructures, phase transitions, and compatibility of starch, as well as application-oriented techniques, including processing methods, plasticizer selection, and chemical modifications. Plasticizers play a crucial role in developing starch-based materials, as they mitigate brittleness and improve processability. Given the abundance of hydroxyl groups in starch, the plasticizers used must also contain hydroxyl or polar groups for compatibility. Chemical modification, such as esterification and etherification, effectively prevents starch recrystallization. Reinforcements, particularly with nanocellulose, significantly improved the mechanical properties of starch film. Drawing upon both the literature and our expertise, this review not only summarizes the advancements in this field but also identifies the limitations of current technologies and outlines promising research directions for future development.

Retrospective comparison of outcomes in septic peritonitis with or without closed-suction abdominal drainage in 115 dogs (2009-2019)

Septic peritonitis is a serious medical condition affecting veterinary patients and post-operative care remains controversial. This study aimed to evaluate and compare post-operative outcomes of dogs treated for septic peritonitis with and without surgically placed closed-suction abdominal drains. Medical records were retrospectively searched from the years 2009 through 2019 and one hundred and fifteen dogs with confirmed septic peritonitis treated with exploratory laparotomy were included. Twenty-two dogs had closed suction drains placed and ninety-three dogs were managed without post-operative drainage. Overall survival to discharge rate of patients in this study was 72%. The survival rate of patients with an abdominal drain was 53% compared to 77% in patients without a drain (P < 0.0001). Dogs with a higher APPLEfast score were significantly more likely to have a drain placed at the time of surgery (P = 0.0277). Dogs that had a closed-suction drain were significantly more likely to be given colloidal support compared to dogs managed without drainage (P = 0.0342). Based on this data, closed-suction drainage post-operatively for treatment of septic peritonitis was not associated with a more favorable survival outcome. The use of a severity of illness score, APPLEfast, did not show a correlation between severity of illness and survival outcome but did demonstrate a correlation between illness severity and placement of a closed-suction drain. Closed-suction drainage post-operatively increased the likelihood of receiving colloidal support, but due to the retrospective nature of the study and the lack of standardized post-operative nutritional support, definitive conclusion that post-operative drainage alone led to increased colloidal support cannot be made in this study.

A Critical Reassessment of the Kidney Risk Caused by Tetrastarch Products in the Perioperative and Intensive Care Environments

Purpose: To reassess the results of former meta-analyses focusing on the relationship between novel HES preparations (130/0.4 and 130/0.42) and acute kidney injury. Previous meta-analyses are based on studies referring to partially or fully unpublished data or data from abstracts only. Methods: The studies included in the former meta-analyses were scrutinized by the authors independently. We completed a critical analysis of the literature, including the strengths, weaknesses and modifiers of the studies when assessing products, formulations and outcomes. Results: Both the published large studies and meta-analyses show significant bias in the context of the deleterious effect of 6% 130/0.4-0.42 HES. Without (1) detailed hemodynamic data, (2) the exclusion of other nephrotoxic events and (3) a properly performed evaluation of the dose-effect relationship, the AKI-inducing property of 6% HES 130/0.4 or 0.42 should not be considered as evidence. The administration of HES is safe and effective if the recommended dose is respected. Conclusions: Our review suggests that there is questionable evidence for the deteriorating renal effect of these products. Further well-designed, randomized and controlled trials are needed. Additionally, conclusions formulated for resource-rich environments should not be extended to more resource-scarce environments without proper qualifiers provided.

Diselenide-triggered hydroxyethyl starch conjugate nanoparticles with cascade drug release properties for potentiating chemo-photodynamic therapy

A novel type of diselenide bond-bridged hydroxyethyl starch-doxorubicin conjugate, HES-SeSe-DOX, was synthesized via a specially designed multistep synthetic route. The optimally achieved HES-SeSe-DOX was further combined with photosensitizer, chlorin E6 (Ce6), to self-assemble into HES-SeSe-DOX/Ce6 nanoparticles (NPs) for potentiating chemo-photodynamic anti-tumor therapy via diselenide-triggered cascade actions. HES-SeSe-DOX/Ce6 NPs were observed to disintegrate through the cleavage or oxidation of diselenide-bridged linkages in response to the stimuli arising from glutathione (GSH), hydrogen peroxide and Ce6-induced singlet oxygen, respectively, as evidenced by the enlarged size with irregular shapes and cascade drug release. In vitro cell studies exhibited that HES-SeSe-DOX/Ce6 NPs in combination with laser irradiation effectively consumed intracellular GSH and promoted a large rise in levels of reactive oxygen species in tumor cells, actuating the disruption of intracellular redox balance and the enhanced chemo-photodynamic cytotoxicity against tumor cells. The in vivo investigations revealed that HES-SeSe-DOX/Ce6 NPs were inclined to accumulate in tumors with persistent fluorescence emission, inhibited tumor growth with high efficacy and had good safety. These findings demonstrate the potential of HES-SeSe-DOX/Ce6 NPs for use in chemo-photodynamic tumor therapy and suggest their viability for clinical translation.

Recent advances of antibacterial starch-based materials

Starch has attracted a lot of attention because it is biodegradable, renewable, nontoxic and low cost. By adding antibacterial substances to starch, starch-based materials have antibacterial properties. The composite with other materials can improve the comprehensive performance of starch-based materials, thus broadening the application field of the material. In this paper, we focus on antibacterial starch-based materials and review their preparation and applications. It was found that antibacterial starch-based materials were most widely used in packaging, followed by medicine, and the research on smart starch-based materials was relatively less. This review may provide some reference value for subsequent studies of starch-based materials.

Polymersome-based protein drug delivery - quo vadis?

Protein-based therapeutics are an attractive alternative to established therapeutic approaches and represent one of the fastest growing families of drugs. While many of these proteins can be delivered using established formulations, the intrinsic sensitivity of proteins to denaturation sometimes calls for a protective carrier to allow administration. Historically, lipid-based self-assembled structures, notably liposomes, have performed this function. After the discovery of polymersome-based targeted drug-delivery systems, which offer manifold advantages over lipid-based structures, the scientific community expected that such systems would take the therapeutic world by storm. However, no polymersome formulations have been commercialised. In this review article, we discuss key obstacles for the sluggish translation of polymersome-based protein nanocarriers into approved pharmaceuticals, which include limitations imparted by the use of non-degradable polymers, the intricacies of polymersome production methods, and the complexity of the in vivo journey of polymersomes across various biological barriers. Considering this complex subject from a polymer chemist's point of view, we highlight key areas that are worthy to explore in order to advance polymersomes to a level at which clinical trials become worthwhile and translation into pharmaceutical and nanomedical applications is realistic.

Quantitative analysis of degree of substitution/molar substitution of etherified polysaccharide derivatives

Due to the unique properties such as nontoxicity, biodegradability, availability from renewable resources, and cost-effectiveness, polysaccharides play a very important part in the science and technology field. The various chemically modified derivatives of these offer a wide range of high value-added in both food and non-food industries. Among the chemical modification, etherified polysaccharide is one of the most widespread derivatives by introducing an ether group which is commonly stable in both acidic and alkaline conditions. Hydroxyalkylation, alkylation, carboxymethylation, cationization, and cyanoethylation are some of the modifications commonly employed to prepare polysaccharides ethers derivatives. There also has been a growing tendency for creating new types of modification by combining the different means of chemical techniques. The correct determination of degree of substitution (DS)/molar substitution (MS) is crucially important. The objective of this article is to summarize developments in synthetic etherified polysaccharides, involving analytical methods for determination of MS/DS, measurement processes, and the associated mechanisms.

Assessment of Hydroxyethyl Starch (6% HES 130/0.4) Kidney Storage in Critically Ill Dogs: A Post-mortem Prospective Study

Objective: Intravenous hydroxyethyl starch (HES) solutions are potentially nephrotoxic due to rapid renal tissue uptake, subsequent osmotic nephrosis, and long-lasting intracellular storage. This study aimed to investigate the severity of intracellular storage of HES in renal tissue samples from critically ill dogs receiving 6% HES 130/0.4.

Materials and Methods: Fresh, post-mortem (<2 h after death) renal tissue samples were analyzed through histology, immunohistochemistry (HES 130/0.4-specific antibodies), and electron microscopy for the severity of renal tubular vacuolization (VAC), intravacuolar HES accumulation (ACC), and ultra-structure impairment. Moreover, we investigated the relationship between VAC or ACC grade and HES dose (mL/kg), duration of HES administration (h), and pre-HES plasma creatinine concentrations.

Results: Histology revealed that 2/20 dogs (10%) had no, 11/20 dogs (55%) had mild, 5/20 dogs (25%) had moderate, and 2/20 dogs (10%) had severe VAC. Immunohistochemistry revealed that 5/20 dogs (25%) had no, 6/20 dogs (30%) had mild, 7/20 dogs (35%) had moderate, and 2/20 dogs (10%) had severe ACC. Both changes were predominantly found in the distal tubular epithelium of mild and moderate cases, and all tubular segments were affected in severe cases. Seven of 20 dogs (35%) had osmotic nephrosis (ON). On electron microscopy, large granules with an electron-dense content were repeatedly detected in individual cells, mainly in the distal tubules. No correlation was found between cumulative HES dose or duration of HES administration and VAC grade, ACC grade, or presence/absence of ON.

Conclusion: A high percentage of dogs had renal tubular HES storage and one-third of dogs showed HES-induced ON. Short-term HES administration caused VAC and ACC, regardless of the dose or duration of administration. In contrast to previous studies, HES 130/0.4 deposits were mainly located in the renal distal tubule.

Stage 1-Biomarkers of Kidney Injury in Dogs Undergoing Constant Rate Infusion of Hydroxyethyl Starch 130/0.4

In veterinary medicine, investigations relating the effects of hydroxyethyl starch (HES) on renal function report contrasting results. This study aimed to assess the changes in the selected biomarkers of kidney injury in dogs after the administration of HES 130/0.4 as a constant rate infusion (CRI) for 24 h. Ten adult client-owned dogs with hypoalbuminemia (albumin < 2 g/dL) and ongoing fluid losses were included. Enrolled dogs received intravenous fluid therapy with crystalloids and a CRI of HES 130/0.4 at a dose of 2 mL/kg/h for 24 h. Serum creatinine (sCr), fractional excretion (FE) of electrolytes, urinary protein to creatinine ratio (UPC), urinary albumin to creatinine ratio (UAC), SDS-page, and urinary neutrophil gelatinase-associated lipocalin (uNGAL) were measured at the baseline before HES infusion, and after 24 h (T24) and 48 h (T48) from the baseline. No statistically significant difference was found between the baseline value vs. T24 and the baseline vs. T48 for sCr, UAC, UPC, FE of sodium, chloride and calcium, and uNGAL. A significant increase in FEK (p = 0.04) was noticed between the baseline and T48. In this study sample of hypoalbuminemic dogs, HES 130/0.4 at the dose and rate of infusion applied did not cause any significant changes in the investigated biomarkers of kidney injury.

Hemorrhagic shock and hemostatic resuscitation in canine trauma

Hemorrhage is a significant cause of death among military working dogs and in civilian canine trauma. While research specifically aimed at canine trauma is limited, many principles from human trauma resuscitation apply. Trauma with significant hemorrhage results in shock and inadequate oxygen delivery to tissues. This leads to aberrations in cellular metabolism, including anaerobic metabolism, decreased energy production, acidosis, cell swelling, and eventual cell death. Considering blood and endothelium as a single organ system, blood failure is a syndrome of endotheliopathy, coagulopathy, and platelet dysfunction. In severe cases following injury, blood failure develops and is induced by inadequate oxygen delivery in the presence of hemorrhage, tissue injury, and acute stress from trauma. Severe hemorrhagic shock is best treated with hemostatic resuscitation, wherein blood products are used to restore effective circulating volume and increase oxygen delivery to tissues without exacerbating blood failure. The principles of hemostatic resuscitation have been demonstrated in severely injured people and the authors propose an algorithm for applying this to canine patients. The use of plasma and whole blood to resuscitate severely injured canines while minimizing the use of crystalloids and colloids could prove instrumental in improving both mortality and morbidity. More work is needed to understand the canine patient that would benefit from hemostatic resuscitation, as well as to determine the optimal resuscitation strategy for these patients.

Doxorubicin-Bound Hydroxyethyl Starch Conjugate Nanoparticles with pH/Redox Responsive Linkage for Enhancing Antitumor Therapy

BACKGROUND

Chemotherapeutic drugs used for tumor treatments often show limited efficiency due to their short lifetime, nonspecific delivery, and slow or insufficient intracellular drug release, and also, they can cause severe system or organ toxicity. The development of chemotherapeutic nanomedicines with high efficacy and satisfactory safety still remains a challenge for current tumor chemotherapy.

METHODS

A novel type of conjugate was synthesized using hydroxyethyl starch (HES) as a carrier while binding doxorubicin (DOX) onto HES backbone through a pH/redox responsive linker containing both disulfide and hydrazone bonds in series. The built conjugates were self-assembled into nanoparticles (NPs) (HES-SS-hyd-DOX NPs) for achieving enhanced antitumor therapy and adequate safety.

RESULTS

HES-SS-hyd-DOX NPs had a certain ability for the tumor-orientated drug accumulation and were capable of releasing DOX itself rather than DOX derivatives. It was found that the pH/redox responsive linkage enabled the NPs to achieve fast and sufficient intracellular drug release. Based on the tumor-bearing mouse model, antitumor results demonstrated that these NPs were able to inhibit the growth of the advanced tumors with significantly enhanced efficacy when compared to free DOX, and to those conjugate NPs containing only a single responsive or unresponsive bond. Besides, HES-SS-hyd-DOX NPs also showed adequate safety to the normal organs of the treated mice.

CONCLUSION

The pH/redox responsive linkage in HES-SS-hyd-DOX was found to play a critical role in mediating the drug accumulation and the fast and sufficient intracellular drug release. The HES-exposed surface of HES-SS-hyd-DOX NPs endowed the NPs with long circulation capability and remarkably reduced the DOX-induced side effects.

Colloids Yes or No? - a "Gretchen Question" Answered

Colloid solutions, both natural and synthetic, had been widely accepted as having superior volume expanding effects than crystalloids. Synthetic colloid solutions were previously considered at least as effective as natural colloids, as well as being cheaper and easily available. As a result, synthetic colloids (and HES in particular) were the preferred resuscitation fluid in many countries. In the past decade, several cascading events have called into question their efficacy and revealed their harmful effects. In 2013, the medicines authorities placed substantial restrictions on HES administration in people which has resulted in an overall decrease in their use. Whether natural colloids (such as albumin-containing solutions) should replace synthetic colloids remains inconclusive based on the current evidence. Albumin seems to be safer than synthetic colloids in people, but clear evidence of a positive effect on survival is still lacking. Furthermore, species-specific albumin is not widely available, while xenotransfusions with human serum albumin have known side effects. Veterinary data on the safety and efficacy of synthetic and natural colloids is limited to mostly retrospective evaluations or experimental studies with small numbers of patients (mainly dogs). Large, prospective, randomized, long-term outcome-oriented studies are lacking. This review focuses on advantages and disadvantages of synthetic and natural colloids in veterinary medicine. Adopting human guidelines is weighed against the particularities of our specific patient populations, including the risk-benefit ratio and lack of alternatives available in human medicine.

Intravenous Fluid Administration and the Coagulation System

Intravenous fluid administration in veterinary patients can alter coagulation function by several mechanisms. Both crystalloid and colloid fluids cause hemodilution, reducing platelet count and plasma coagulation protein concentrations. Hemodilution is associated with a hypercoagulable effect at low dilutions and a hypocoagulable effect at higher dilutions. Composition of crystalloid fluids likely has a minor effect, primarily dependent on fluid ion composition. Hypertonic crystalloids may also cause hypocoagulability. Colloids, both synthetic and natural, can cause hypocoagulability by several mechanisms beyond the effects of hemodilution. These include impaired platelet function, decreased plasma coagulation factor activity, impaired fibrin formation and crosslinking, and accelerated fibrinolysis. The vast majority of the veterinary literature investigates the hypocoagulable effects of hydroxyethyl starch-containing fluids using in vitro, experimental, and clinical studies. However, results are inconsistent, likely due to the varying doses and physicochemical properties of the specific fluid products across studies. In addition, some evidence exists for hypocoagulable effects of gelatin and albumin solutions. There is also evidence that these colloids increase the risk of clinical bleeding in people. Limitations of the veterinary evidence for the hypocoagulable effects of colloid fluids include a predominance of in vitro studies and in vivo studies using healthy subjects, which exclude the interaction of the effects of illness. Therefore, clinical relevance of these effects, especially for low-molecular-weight hydroxyethyl starch, is unknown. Firm recommendations about the most appropriate fluid to use in clinical scenarios cannot be made, although it is prudent to limit the dose of synthetic colloid in at-risk patients. Clinicians should closely monitor relevant coagulation assays and for evidence of hemorrhage in at-risk patients receiving any type of fluid therapy, especially in large volumes.

Crystalloid and Colloid Compositions and Their Impact

This manuscript will review crystalloid (hypo-, iso-, and hyper-tonic) and colloid (synthetic and natural) fluids that are available for intravenous administration with a focus on their electrolyte, acid-base, colligative, and rheological effects as they relate to each solution's efficacy and safety. The goal is for the reader to better understand the differences between each fluid and the influence on plasma composition, key organ systems, and their implications when used therapeutically in animals with critical illness.

Understanding Volume Kinetics: The Role of Pharmacokinetic Modeling and Analysis in Fluid Therapy

Fluid therapy is a rapidly evolving yet imprecise clinical practice based upon broad assumptions, species-to-species extrapolations, obsolete experimental evidence, and individual preferences. Although widely recognized as a mainstay therapy in human and veterinary medicine, fluid therapy is not always benign and can cause significant harm through fluid overload, which increases patient morbidity and mortality. As with other pharmaceutical substances, fluids exert physiological effects when introduced into the body and therefore should be considered as "drugs." In human medicine, an innovative adaptation of pharmacokinetic analysis for intravenous fluids known as volume kinetics using serial hemoglobin dilution and urine output has been developed, refined, and investigated extensively for over two decades. Intravenous fluids can now be studied like pharmaceutical drugs, leading to improved understanding of their distribution, elimination, volume effect, efficacy, and half-life (duration of effect) under various physiologic conditions, making evidence-based approaches to fluid therapy possible. This review article introduces the basic concepts of volume kinetics, its current use in human and animal research, as well as its potential and limitations as a research tool for fluid therapy research in veterinary medicine. With limited evidence to support our current fluid administration practices in veterinary medicine, a greater understanding of volume kinetics and body water physiology in veterinary species would ideally provide some evidence-based support for safer and more effective intravenous fluid prescriptions in veterinary patients.

Evaluation of the Distribution and Elimination of Balanced Isotonic Crystalloid, 5% Hypertonic Saline, and 6% Tetrastarch 130/0.4 Using Volume Kinetic Modeling and Analysis in Healthy Conscious Cats

This prospective, randomized, blinded, interventional cross-over study investigated the distribution, elimination, plasma volume expansion, half-life, comparative potency, and ideal fluid prescription of three commonly prescribed intravenous (IV) fluids in 10 healthy conscious cats using volume kinetic analysis that is novel to veterinary medicine. Each cat received 20 mL/kg of balanced isotonic crystalloid (PLA), 3.3 mL/kg of 5% hypertonic saline (HS), and 5 mL/kg of 6% tetrastarch 130/0.4 (HES) over 15 min on separate occasions. Hemoglobin concentration, red blood cell count, hematocrit, heart rate, and blood pressure were measured at baseline, 5, 10, 15, 20, 30, 40, 50, 60, and every 15 min until 180 min. Urine output was estimated every 30 min using point-of-care bladder ultrasonography. Plasma dilution derived from serial hemoglobin concentration and red blood cell count served as input variables for group and individual fluid volume kinetic analyses using a non-linear mixed effects model. In general, the distribution of all IV fluids was rapid, while elimination was slow. The half-lives of PLA, HS, and HES were 49, 319, and 104 min, respectively. The prescribed fluid doses for PLA, HS, and HES resulted in similar peak plasma volume expansion of 27–30%. The potency of HS was 6 times higher than PLA and 1.7 times greater than HES, while HES was 3.5 times more potent than PLA. Simulation of ideal fluid prescriptions to achieve and maintain 15 or 30% plasma volume expansion revealed the importance of a substantial reduction in infusion rates following initial IV fluid bolus. In conclusion, volume kinetic analysis is a feasible research tool that can provide data on IV fluid kinetics and body water physiology in cats. The rapid distribution but slow elimination of IV fluids in healthy conscious cats is consistent with anecdotal reports of fluid overload susceptibility in cats and warrants further investigation.

A prospective randomized open-label trial on the comparative effects of 6% hydroxyethyl starch 130/0.4 versus polyionic isotonic crystalloids on coagulation parameters in dogs with spontaneous hemoperitoneum

OBJECTIVE

To evaluate the effects of 6% hydroxyethyl starch 130/0.4 (HES) and a polyionic isotonic crystalloid (CRYS) on standard coagulation tests and rotational thromboelastometry (ROTEM) in dogs with spontaneous hemoperitoneum (SHP).

DESIGN

Prospective randomized open-label clinical study.

SETTING

University teaching hospital.

ANIMALS

Forty-two client-owned dogs presented with SHP.

INTERVENTIONS

Dogs diagnosed with SHP and hypovolemic shock were randomly allocated to receive HES (10 mL/kg, n = 22) or CRYS (30 mL/kg, n = 20) intravenously over 20 minutes for hemodynamic stabilization.

MEASUREMENTS AND MAIN RESULTS

Parameters measured before (T₀ ) and after (T₁ ) treatment were HCT, platelet counts, prothrombin time, activated partial thromboplastin time, fibrinogen concentrations, and extrinsic activated (EXTEM), intrinsic activated (INTEM), and extrinsic activated with platelet inhibition ROTEM assays. Data were analyzed as absolute values and as the percentage change from T₀ to T₁ . No significant differences between groups were detected in any variable at T₀ , and for HCT, platelet counts, prothrombin time, activated thromboplastin time, and fibrinogen concentrations at T₁ . Clot formation time in EXTEM was significantly prolonged (P = 0.037), and maximum clot firmness was significantly decreased (P = 0.038) in the HES group compared to the CRYS group at T₁ . The percentage change in EXTEM clotting time (P = 0.012) and INTEM clot formation time (P = 0.031) was greater after HES than CRYS. Lysis indices remained at 100% for all ROTEM assays in both groups.

CONCLUSION

Compared to a 3-fold volume of CRYS, administration of HES was associated with impairment in ROTEM parameters in dogs with SHP, but no evidence of hyperfibrinolysis was detected.

Evaluation of the effects of hydroxyethyl starch (130/0.4) administration as a constant rate infusion on plasma colloid osmotic pressure in hypoabluminemic dogs

OBJECTIVE

To evaluate the effects of 2 constant rate infusions of hydroxyethyl starch (HES) 130/0.4 on plasma colloid osmotic pressure (COP) in hypoalbuminemic dogs.

DESIGN

Prospective, randomized clinical trial.

ANIMALS

A total of 24 client-owned dogs.

INTERVENTIONS

Hypoalbuminemic euvolemic dogs (albumin < 20 g/L [<2 g/dL]) with normal perfusion parameters requiring IV fluid therapy were enrolled. In addition to crystalloid, HES 130/0.4 was administered as a constant rate infusion over 24 hours at 1 mL/kg/h (group 1, n = 15) or at 2 mL/kg/h (group 2, n = 9), in order to support plasma COP. Before infusion, a blood sample was collected to perform CBC, serum electrophoresis, and serologic tests for some infective diseases. Plasma COP, albumin concentration, PCV, and total plasma protein concentration were evaluated serially at baseline (T0) and then at 6, 12, and 24 hours after the start of infusion, and a multilevel model was performed for these parameters to detect statistically significant differences between the 2 groups.

MEASUREMENT AND MAIN RESULTS

Twenty-four dogs were included. No statistically significant differences in COP were found between the 2 groups; however, a high level of variability has been identified within the single individual. Among the other laboratory analyses, PCV was significantly decreased in group 1 at T12 and T24 compared with T0 (P < 0.001) and total plasma protein concentration was significantly increased in group 2 at T12 and T24 compared with T0 (P < 0.008).

CONCLUSION

No significant effect on plasma COP was found following infusion with HES 130/0.4 at doses of 1 mL/kg/h and 2 mL/kg/h for 24 hours to hypoalbuminemic dogs. The administered concomitant dose of crystalloids, underlying disease, and small sample size were all potential confounding factors.

Evaluation of the hydroxyethyl starch stabilizing agent, Vetstarch, in the preservation of canine cerebrospinal fluid samples

BACKGROUND

A challenge of cerebrospinal fluid (CSF) analysis is the time-dependent degradation of nucleated cells, impeding accurate interpretation. CSF additives have been used to delay cell degradation; however, stabilizing agents, including serum, can alter microprotein levels.

OBJECTIVES

This study aimed to determine if the hydroxyethyl starch, Vetstarch, is effective at preserving nucleated cell morphology in CSF compared with the saline diluent or serum without altering microprotein levels.

METHODS

CSF samples were collected from 26 dogs. Samples were divided into four aliquots. One aliquot was analyzed immediately (control). The remaining three aliquots were mixed with either saline, fetal calf serum, or Vetstarch before storage at 4°C. Nucleated cell differentials, protein concentrations, and cell morphology scores were analyzed 48 hours later. A cell morphology score of 1 indicated no cellular degeneration; a score of 4 indicated severe degeneration.

RESULTS

Samples stored in serum, saline, and Vetstarch exhibited poorer mean (±SD) morphology scores (2.4 ± 0.7, 2.6 ± 0.8, and 2.7 ± 0.9, respectively) compared with controls (1.9 ± 0.4). Samples stored in saline and Vetstarch demonstrated higher percentages of unrecognizable cells, with a median of 28 (range 0-100) and 27 (0-100), respectively; samples stored in serum had a median of 14 (range 0-67) unrecognizable. Microprotein levels of samples stored in Vetstarch were dependent on the method of protein analysis. Serum significantly increased microprotein levels.

CONCLUSIONS

Vetstarch does not reduce time-dependent cellular degeneration compared with the saline diluent or serum and is, therefore, not recommended as a stabilizing agent for canine cerebrospinal fluid.

Purification of canine albumin by heat denaturation in a plasma bag

OBJECTIVE

To design and evaluate a method to purify canine albumin from fresh frozen plasma (FFP) or stored plasma (SP) in a manner that could be applied clinically.

DESIGN

In vitro experimental study.

SETTING

FDA licensed Blood Bank Laboratory and University biochemistry laboratory.

ANIMALS

None.

INTERVENTIONS

Using equipment that is typically found in veterinary blood banks, plasma bags were thawed, injected with the heat stabilizing agent, sodium caprylate, and then heated and acidified to denature all but albumin proteins. Albumin-rich supernatant was removed, the pH was neutralized, and then pasteurized and refrigerated. Albumin and total plasma protein concentrations were measured and the product was cultured for bacteria at 0, 7, 14, 30, and 60 days post-processing.

MEASUREMENTS AND MAIN RESULTS

Seventeen bags of plasma were analyzed for purity, yield, and sterility of the finished albumin product. Bags were divided into categories based on the age of the frozen plasma. Mean yield of albumin for all bags was 77.3% and mean purity was 91.2%. There was no difference between old stored plasma, new stored plasma, and FFP with regard to yield (P = 0.31) or purity (P = 0.24) based on one-way analysis of variances. Overall 1 of 17 bags of plasma (5.9%) tested positive for bacterial contamination on day 60 after processing.

CONCLUSIONS

Sodium caprylate is able to stabilize canine albumin enabling it to withstand heating that denatures other plasma proteins. The resulting albumin product is of sufficient quality to potentially be used therapeutically as a colloidal resuscitative fluid. Further study is needed into its safety and effect in dogs.

In vitro effects of lactated Ringer's solution, hypertonic saline, hydroxyethyl starch, hypertonic saline/hydroxyethyl starch, and mannitol on thromboelastographic variables of canine whole blood

OBJECTIVE

To assess the in vitro effects of crystalloid and colloid IV fluids on the thromboelastographic (TEG) variables of canine whole blood.

DESIGN

In vitro experimental study.

SETTING

Veterinary teaching hospital.

ANIMALS

Twenty-two healthy dogs.

INTERVENTION

Citrated whole blood samples collected from healthy dogs were diluted with 3.4% hypertonic saline (HTS 3.4), 7% hypertonic saline (HTS 7), and 20% mannitol at 8% and 16% dilutions; hydroxyethyl starch 130/0.4 (HES 130/0.4) at 16% dilution; lactated Ringer's solution (LRS) at 16%, 33%, and 66% dilutions; and HTS 7-HES 130/0.4 at 25% and 50% dilutions. Kaolin-activated TEG analysis was concurrently performed on diluted and control (undiluted) samples.

MEASUREMENTS AND MAIN RESULTS

Dilution of canine whole blood with LRS compared to control reduced α angle and MA at both 33% (P = 0.009 and P = 0.011, respectively) and 66% dilution (P < 0.001 and P < 0.001, respectively), and prolonged K time at 66% dilution (P = 0.003). At 16% dilution, HTS 3.4, prolonged R time (P = 0.007), while mannitol, a fluid iso osmolar to HTS 3.4, prolonged K time (P = 0.006), reduced α angle (P < 0.001), MA (P = 0.046), and LY60 (P = 0.015). At 8% dilution, HTS 7, a fluid of high osmolarity and tonicity, prolonged R time (P = 0.009) and reduced MA (P = 0.015), while all measured TEG variables were altered at the 16% dilution (P < 0.01 for all variables). HES 130/0.4 reduced α angle (P = 0.031) and MA (P = 0.001) and increased LY60 (P < 0.001) at 16% dilution. Comparing different fluid types, HES 130/0.4 and HTS 3.4 had no to minor, mannitol intermediate, and HTS 7 profound effects on TEG variables (P < 0.05) when compared to LRS at the same dilution.

CONCLUSIONS

In vitro dilution of canine whole blood with commonly used IV fluids leads to thromboelastographic changes consistent with hypocoagulability in a dose dependent manner for all fluid types tested. Viscoelastic changes are also influenced by fluid characteristics, specifically tonicity and osmolarity.

Large volume infusions of hydroxyethyl starch during cardiothoracic surgery may be associated with postoperative kidney injury: propensity-matched analysis

Background

The safety of intraoperative administration of hydroxyethyl starch (HES) has been debated. We hypothesized that intraoperative use of HES is associated with postoperative acute kidney injury (AKI) following cardiopulmonary bypass (CPB).

Materials and methods

Patients who underwent cardiothoracic surgery using CPB between 2007 and 2014 were retrospectively reviewed. The incidence of AKI within 7 days after surgery, defined by the Kidney Disease Improving Global Outcome criteria, was compared for patients who did or did not receive 6% (70/0.5) or 6% (130/0.4) HES for anesthesia management before or after CPB. Multivariable logistic regression and propensity matching analysis were performed to examine whether use of HES is associated with postoperative AKI. Outcomes comparing patients receiving HES ≥ 1000 mL and < 1000 mL were also compared.

Results

Data from 1976 patients were reviewed. All patients received 70/0.5 HES as a part of the priming solution for CPB. The incidence of postoperative AKI was 28.2% in patients who received HES and 26.0% in patients who did not (p = 0.33). In multivariable analysis, there was no correlation between the use of HES and the incidence of AKI (odds ratio 0.87, 95% CI 0.30–2.58, p = 0.81). Propensity matching showed that the incidence of AKI was not significantly different between 481 patients administered with HES and 962 patients (26.6% vs. 26.9%, p = 0.95) who did not receive HES for anesthesia management. However, peak creatinine levels, needed for renal replacement therapy, and in-hospital mortality were higher, and 28-day hospital-free days were lower in patients receiving HES ≥ 1000 mL than those receiving HES < 1000 mL (p < 0.05).

Conclusions

Intraoperative use of HES was not associated with postoperative AKI following CPB. However, administration of large volumes of HES may be associated with kidney-related adverse clinical outcomes.

Hydroxyethyl starches in equine medicine

OBJECTIVE

To review and discuss the use of hydroxyethyl starches (HES) in equine veterinary medicine, and to provide recommendations for its use.

DATA SOURCES

Veterinary and human peer-reviewed medical literature including scientific reviews, meta-analyses, and original research articles.

HUMAN DATA SYNTHESIS

Increasing evidences on adverse effects after HES use and decreasing support for beneficial effects with regards to volume expansion and colloid osmotic pressure (COP) support in critically ill subjects have led to a recent guideline to limit the use of HES in critically ill people.

EQUINE VETERINARY DATA SYNTHESIS

The rationale for HES use in horses is mainly extrapolated from human medicine, and very limited studies in horses are available. There is limited evidence suggesting a superiority of volume expansion effects of HES over crystalloids. The potential for HES to increase and maintain COP is well supported, but there is no evidence that maintaining or increasing plasma COP influences outcome, tissue edema formation, or rates of complications that potentially relate to edema formation. HES induce dose-dependent changes in coagulopathic parameters, but there is no evidence that HES causes clinical coagulopathies. Insufficient data are available on other adverse effects such as acute kidney injury, or mortality in horses. The use of HES should be restricted in septic patients, but may still have some use in cases of hemorrhagic shock resuscitation, hypoalbuminemia, or perioperative fluid replacement.

CONCLUSION

The evidence supporting the use of HES in horses is weak due to lack of species-specific investigations. Acknowledging species differences, the use of HES should be judicious, yet with some recognition of its benefits in particular cases. More research is necessary to improve knowledge on use of HES in horses and to establish better future recommendations.

Retrospective evaluation of paired plasma creatinine and chloride concentrations following hetastarch administration in anesthetized dogs (2002-2015): 244 cases

OBJECTIVE

To evaluate changes in serum creatinine and chloride concentrations in anesthetized dogs that received 6% hydroxyethyl starch (HES) 670/0.7.

DESIGN

Retrospective case series, 2002-2015.

SETTING

University veterinary teaching hospital.

ANIMALS

Two hundred forty-four client-owned dogs undergoing general anesthesia that received an HES solution.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records of dogs that received an HES solution (6%, 670/0.7) while under general anesthesia during the study period were reviewed. Information obtained from the medical record included patient signalment, reason for anesthesia or diagnosis, body weight, amount of HES solution administered, pre- and postanesthesia creatinine value, pre- and postanesthesia chloride value, and day interval between measurements. Corrected chloride values were used for all statistical analysis. Dogs received a median dose of 6.3 mL/kg hetastarch during anesthesia. Median preanesthesia creatinine and corrected chloride values were 79.5 μmol/L (0.9 mg/dL) (range 8.8-689.5 μmol/L [0.1-7.8 mg/dL]) and 111 mmol/L (111 mEq/L) (range 80-123 mmol/L [80-123 mg/dL]), respectively. Median postanesthesia creatinine was 57.4 μmol/L (0.65 mg/dL) (8.8-716 μmol/L [0.1-8.1 mg/dL]). Median postanesthesia corrected chloride was 115 mmol/L (115 mEq/L) (range 87.5-129.6 mmol/L [87.5-129.6 mEq/L]). Mann-Whitney test analysis revealed a significant decrease in creatinine (Δ Cr 17.7 μmol/L [0.2 mg/dL], P < 0.01) and a significant increase in corrected chloride (Δ Cl 4.1 mmol/L [4.1mEq/L], P < 0.01) between pre- and postanesthesia values.

CONCLUSIONS

In a mixed population of hospitalized dogs undergoing general anesthesia that received a median dose of 6 mL/kg of HES, creatinine was lower and chloride was higher in the postanesthetic than in the preanesthetic period. The clinical significance of these changes and the role that HES administration played in them relative to concurrent therapies is unknown.

Trauma Management of Military Working Dogs

There are about 2,500 war and military service dogs in service, with about 700 serving at any given time overseas. Military Working Dogs (MWDs) are critical assets for military police, special operations units, and others operating in today's combat environment. The expectation, given the significant combat multiplier impact of these dogs and the intense bond between the handler and dog, is that injured working dogs will receive the same level of care as any injured U.S. military personnel. Veterinary care is available at multiple locations throughout theater, and the veterinary healthcare team is the MWD's primary provider. Yet, human healthcare providers (HCPs) may be the only medical personnel available to MWDs that are gravely ill or injured. As most HCPs are unfamiliar with medical care of dogs, the Joint Trauma System published a Clinical Practice Guideline (CPG), a set of detailed clinical guidelines for managing life-threatening problems of MWDs encountered in combat operations. The CPG is available at the JTS website. This article is covers the most common urgent MWD care challenges HCPs may face.

Colloidal hydroxyethyl starch for tumor-targeted platinum delivery

Cis-platinum has been widely used as a first-line chemotherapy agent in clinics for more than 40 years. Although considerable efforts have been expended for developing platinum-based nano drug delivery systems (NDDS) to resolve the problems of low water solubility, short half-life, and severe side effects of cis-platinum, it remains challenging to apply these nanoplatforms to cancer treatments in clinics on account of the issues related to safety, complex fabrication procedures, and limited cellular uptake. Herein, we constructed a novel cis-platinum delivery system with hydroxyethyl starch (HES), which is a semisynthetic polysaccharide that has been used worldwide as colloidal plasma volume expanders (PVE) in clinics for several decades. By combining TEM, AFM, and DLS, we have found that HES particles are colloidal nanoparticles in solution, with diameters ranging from 15 to 40 nm as a function of molecular weight. We further revealed that HES adopted a hyperbranched colloidal structure with rather compact conformation. These results demonstrate that HES is a promising nanocarrier to deliver drug molecules. Taking advantage of the poly-hydroxyl sites of HES, we constructed a novel HES-based cis-platinum delivery nanoplatform. HES was directly conjugated with cis-platinum prodrug via an ester bond and decorated with an active targeting molecule, lactobionic acid (LA), contributing toward higher in vitro antitumor activity against hepatoma carcinoma cells as compared to cis-platinum. These results have significant implications for the clinically used plasma volume expander-HES and shed light on the clinical translation of HES-based nano drug delivery systems.

Starch Wars-New Episodes of the Saga. Changes in Regulations on Hydroxyethyl Starch in the European Union

After a safety review of hydroxyethyl starch (HES) solutions in 2013, restrictions on the use of HES were introduced in the European Union (EU) to reduce the risk of kidney injury and death in certain patient populations. Similar restrictions were introduced by the Food and Drug Administration in the United States and other countries. In October 2017, a second safety review of HES solutions was triggered by the European pharmacovigilance authorities based on a request by the Swedish Medical Products Agency to completely suspend HES. After several meetings and repeated evaluations, the recommendation to ban HES was ultimately not endorsed by the responsible committee; however, there was a vote for more restricted access to the drug and rigorous monitoring of policy adherence. This review delineates developments in the European pharmacovigilance risk assessment of HES solutions between 2013 and 2018. In addition, the divergent experts' opinions and the controversy surrounding this official assessment are described. As the new decisions might influence the availability of HES products for veterinary patients, potential alternatives to HES solutions, such as albumin solutions and gelatin, are briefly discussed.

Effects of 6% tetrastarch or lactated Ringer's solution on blood coagulation in hemorrhaged dogs

Background

Tetrastarch solution (TS) can impair coagulation but the clinical relevance of this impairment is unclear in veterinary medicine.

Objective

Compare the effects of volume replacement (VR) with lactated Ringer's solution (LRS) or 6% TS on coagulation in hemorrhaged dogs.

Animals

Six healthy English Pointer dogs (19.7‐35.3 kg).

Methods

Prospective crossover study. Dogs were anesthetized without hemorrhage and VR (control). Two weeks later, dogs were hemorrhaged under anesthesia on 2 occasions (8‐week washout intervals) and randomly received VR with LRS or TS at 3:1 or 1:1 of shed blood, respectively, aiming to decrease the hematocrit to 33%. Rotational thromboelastometry and other coagulation variables were determined before 0.5, 2, and 4 hours after VR during anesthesia and 24 hours after VR (conscious dogs).

Results

Buccal mucosal bleeding time did not differ between treatments after VR. Activated partial thromboplastin time increased from controls 4 hours after TS (P = 0.045). Clot formation time (CFT) and alfa‐angle increased from controls from 0.5 to 4 hours after LRS (CFT, P ≤ 0.0001‐0.02; alpha angle, P = 0.0001‐0.02) and from 0.5 to 2 hours after TS (CFT, P = 0.0002‐0.01; alpha angle, P = 0.0005‐0.02). The maximum clot firmness decreased from controls from 0.5 to 4 hours after LRS (P ≤ 0.0001‐0.01) and TS (P ≤ 0.0001‐0.04).

Conclusions and Clinical Relevance

Tetrastarch does not impair primary hemostasis and induces transient dilutional coagulopathy that is similar to LRS because, when compared to a 3 times higher volume of LRS in hemorrhaged dogs, it does not cause greater interference on the viscoelastic properties of the coagulum.

Treatment of carprofen overdose with therapeutic plasma exchange in a dog

OBJECTIVE

To report the use of therapeutic plasma exchange (TPE) in a dog with carprofen toxicosis.

SUMMARY

A 6-year-old female neutered Bichon Frise weighing 6.9 kg was examined after it had ingested 72 mg/kg carprofen. Mild dehydration without azotemia and with a urine specific gravity of 1.050 was noted at presentation. Treatment consisted of induction of emesis, symptomatic medical therapy, and TPE. The TPE achieved 1.5 plasma volume exchanges over 3 hours. Blood samples and effluent samples were collected every 30 minutes during TPE and additional blood samples were collected 11 and 35 hours after treatment. Carprofen concentrations in these samples were determined by high-pressure liquid chromatography. A 51% reduction in serum carprofen concentration was achieved following TPE.

NEW OR UNIQUE INFORMATION PROVIDED

This report describes the successful reduction of plasma carprofen concentration in a dog using TPE. Although recent studies suggest that this particular dog may not have received a toxic dose, a 51% reduction of plasma carprofen concentration was achieved over 180 minutes, and TPE may be beneficial for treatment of dogs that have ingested higher doses.

The effect of 3 resuscitative fluid therapies on hemostasis as measured by rotational thromboelastometry in dogs

BACKGROUND

Evidence suggests that administration of intravenous fluids impairs hemostasis. Thromboelastometry (TEM) may provide a more sensitive measure of the fluid effects on hemostasis than traditional coagulation tests.

OBJECTIVE

The study aim was to determine if resuscitative fluid therapy affects hemostasis, as measured by TEM.

MATERIALS AND METHODS

Using a randomized crossover design, 6 healthy dogs were administered intravenous colloid, crystalloid, and hypertonic saline at therapeutic doses. Whole blood samples were taken at baseline, 1, 4, and 8 h posttreatment for TEM analysis and measurement of PT, APTT, and fibrinogen. Univariate ANOVA on transformed data evaluated differences between groups and within groups. When significant differences were noted (P = .003), a Tukey test was performed.

RESULTS

A statistically significant interaction between individual dogs and treatment was noted for most TEM variables. There was a significant decrease in clot firmness from baseline in the TEM assessment of the intrinsic pathway. Colloid treatment correlated with significantly higher clot firmness in the TEM extrinsic pathway assessment, which decreased over time, and PT was significantly shorter in colloid-treated dogs. Overall, PT was significantly prolonged at one hour; however, all PT values were within the RI. The fibrinogen concentration was significantly different between all treatments.

CONCLUSIONS

Clinically relevant doses of resuscitative fluids resulted in a decreased clot firmness in the intrinsic pathway, as measured by TEM, which affected hemostatic variables in healthy dogs. There was also a significant individual response to treatment. The changes noted in this study are not expected to result in clinically apparent bleeding.

Thromboelastometric assessment of hemostasis following hydroxyethyl starch (130/0.4) administration as a constant rate infusion in hypoalbuminemic dogs

BACKGROUND

The primary aim was to evaluate by means of thromboelastometry (ROTEM) the effects of hydroxyethyl starch (HES) 130/0.4 administered as a constant rate infusion (CRI) on hemostasis in hypoalbuminemic dogs. The second aim was to use ROTEM analysis to detect whether all hypoalbuminemic dogs of our population were hypercoagulable.

RESULTS

The study sample was 20 hypoalbuminemic dogs (albumin < 2 g/dl) with normal perfusion parameters and requiring intravenous fluid therapy. In order to support plasma colloid osmotic pressure, in addition to crystalloid, HES 130/0.4 was administered as a constant rate infusion at 1 ml/kg/h (group 1, n = 11) or 2 ml/kg/h for 24 h (group 2, n = 9). Blood samples were collected at baseline (T0) and 24 h postinfusion (T1); coagulation was assessed by standard coagulation profile (prothrombin time, activated partial thromboplastin time, and fibrinogen), and ROTEM analysis (in-TEM®, ex-TEM® and fib- TEM® profile). No statistically significant differences in ROTEM values in group 1 were observed (P > 0.05), whereas in group 2 statistically significant differences (P < 0.05) were found at T1 in the in-TEM® profile [decrease in clot formation time (P = 0.04) and increase in α angle (P = 0.02)] and in the ex-TEM® profile [increase in maximum clot firmness (P = 0.008) and α angle (P = 0.01)]; no changes were identified in the fib-TEM® profile. In both groups, a statistically significant decrease (P = 0.007) in hematocrit was noted, whereas no statistically significant differences in platelet count and standard coagulation profile were found. In group 2, a statistically significant increase in TS values (P = 0.03) was noted at T1. ROTEM tracings indicating a hypercoagulable state were observed in 7/20 dogs at T0 (5/11 in group 1 and 2/9 in the group 2).

CONCLUSION

Our findings suggest that HES 130/0.4 administered as CRI does not cause hypocoagulability in hypoalbuminemic dogs. A trend toward hypercoagulability, probably related to the underlying diseases, was observed in group 2 at T1. Although all dogs were hyoalbuminemic, only 7/20 were hypercoagulable at T0, confirming the lack of correlation between albumin level and prothrombotic state.

Effects of 6% Tetrastarch and Lactated Ringer's Solution on Extravascular Lung Water and Markers of Acute Renal Injury in Hemorrhaged, Isoflurane-Anesthetized Healthy Dogs

Background

Tetrastarch can cause acute kidney injury (AKI) in humans with sepsis, but less likely to result in tissue edema than lactated Ringer's solution (LRS).

Objectives

Compare effects of volume replacement (VR) with LRS and 6% tetrastarch solution (TS) on extravascular lung water (EVLW) and markers of AKI in hemorrhaged dogs.

Animals

Six healthy English Pointer dogs (19.7–35.3 kg).

Methods

Prospective crossover study. Animals underwent anesthesia without hemorrhage (Control). Two weeks later, dogs hemorrhaged under anesthesia on 2 occasions (8‐week washout intervals) and randomly received VR with LRS or TS at 3 : 1 or 1 : 1 of shed blood, respectively. Anesthesia was maintained until 4 hour after VR for EVLW measurements derived from transpulmonary thermodilution cardiac output. Neutrophil gelatinase‐associated lipocalin (NGAL) and creatinine concentrations in plasma and urine were measured until 72 hour after VR.

Results

The EVLW index (mL/kg) was lower at 1 hour after TS (10.0 ± 1.9) in comparison with controls (11.9 ± 3.4, P = 0.04), and at 4 hour after TS (9.7 ± 1.9) in comparison with LRS (11.8 ± 2.7, P = 0.03). Arterial oxygen partial pressure‐to‐inspired oxygen fraction ratio did not differ among treatments from 0.5 to 4 hour after VR. Urine NGAL/creatinine ratio did not differ among treatments and remained below threshold for AKI (120,000 pg/mg).

Conclusions and Clinical Importance

Although TS causes less EVLW accumulation than LRS, neither fluid produced evidence of lung edema (impaired oxygenation). Both fluids appear not to cause AKI when used for VR after hemorrhage in healthy nonseptic dogs.

Comparison of acid-base and electrolyte changes following administration of 6% hydroxyethyl starch 130/0.42 in a saline and a polyionic solution in anaesthetized dogs

OBJECTIVE

To evaluate the effects of a 6% hydroxyethyl starch (130/0.42) in either a buffered, electrolyte-balanced (HES-BAL) or saline (HES-SAL) carrier solution on electrolyte concentrations and acid-base parameters in healthy anaesthetized dogs.

STUDY DESIGN

Prospective randomised clinical study.

ANIMALS

A group of 40 client-owned dogs undergoing general anaesthesia for elective surgical procedures or diagnostic imaging.

METHODS

During anaesthesia, dogs were intravenously administered 15 mL kg^-1 of either HES-SAL (n = 20) or HES-BAL (n = 20) over 30-40 minutes. Jugular blood samples were analysed before (T₀) and 5 minutes (T₅), 1 hour (T₆₀) and 3 hours (T₁₈₀) after fluid administration. Sodium, potassium, chloride, ionised calcium, phosphate, albumin, pH, venous pCO₂, base excess (BE), bicarbonate and anion gap were determined and strong ion difference (SID) and total quantity of weak nonvolatile acids were calculated for each time point.

RESULTS

Chloride was significantly increased at T₅, T₆₀ and T₁₈₀ compared with T₀ after HES-SAL, and was significantly greater after HES-SAL than after HES-BAL at T₅ (p = 0.042). Ionised calcium was significantly decreased at T₅ compared with T₀ after HES-SAL, and was significantly lower after HES-SAL than after HES-BAL at T₅ (p < 0.001). Bicarbonate was significantly lower after HES-SAL than after HES-BAL at T₅ (p = 0.004) and T₆₀ (p = 0.032). BE was significantly lower after HES-SAL than after HES-BAL at T₅ (p < 0.001) and T₆₀ (p = 0.007). SID was significantly decreased after HES-SAL at T₅ and T₆₀ compared with T₀, and was significantly lower after HES-SAL than after HES-BAL at T₅ (p = 0.027). Mean electrolyte and acid-base parameters remained within or marginally outside of reference intervals.

CONCLUSIONS AND CLINICAL RELEVANCE

Changes in both groups were minor and short-lived with either fluid in healthy individuals, but might become clinically relevant with higher fluid doses or in critically ill dogs.

Effect of tetrastarch (hydroxyethyl starch 130/0.4) on plasma creatinine concentration in cats: a retrospective analysis (2010-2015)

Objectives The objective was to determine survival and changes in creatinine concentrations after administration of 6% tetrastarch (hydroxyethyl starch [HES] 130/0.4) vs crystalloids in critically ill cats. Methods The medical records were reviewed for cats admitted to the intensive care unit with at least two plasma creatinine measurements and initial concentrations not exceeding the upper reference interval. Cats were excluded if they had received HES prior to admission or if they had received fluid therapy for <24 h between initial and subsequent measurements. Changes in creatinine concentrations were evaluated as the percentage change from initial values to the maximum subsequent measurements. Cats receiving only crystalloids were assigned to the crystalloid group; cats receiving only HES or HES and crystalloids were assigned to the HES group. Results Ninety-three cats were included in the study (62 in the crystalloid group, 31 in the HES group). The total median cumulative HES dose was 94 ml/kg (range 26-422 ml/kg) and 24 ml/kg/day (range 16-42 ml/kg/day). No difference was detected between the groups for age, sex, body weight or mortality. The HES group had a significantly longer length of hospitalisation ( P = 0.012), lower albumin concentrations ( P <0.001), higher Acute Patient Physiologic and Laboratory Evaluation scores ( P = 0.037) and higher incidence of systemic inflammatory response syndrome ( P = 0.009) and sepsis ( P = 0.013). There was no significant difference in initial, maximum or maximum change in creatinine concentrations between the groups. Moreover, there was no significant difference in maximum change in creatinine concentrations in the subgroups of cats with systemic inflammatory response syndrome or sepsis. Conclusions and relevance In this population of cats, the administration of HES did not result in a significantly greater increase in creatinine from values measured on admission or higher mortality compared with administration of crystalloids. Further prospective studies are needed to assess both safety and efficacy of HES in cats before recommendations can be made.

Current Trends in Volume Replacement Therapy and the Use of Synthetic Colloids in Small Animals-An Internet-Based Survey (2016)

The use of synthetic colloids (SCs), particularly hydroxyethyl starch (HES), in people has changed in recent years following new evidence raising concerns about their efficacy and safety. Although fluid therapy guidelines for small animals are often extrapolated from human medicine, little information exists on current practice in veterinary medicine. The objective of the present study was to investigate current fluid selection, use of plasma volume expanders including SCs, and recent changes in their use in small animal practice. An Internet-based survey was conducted, inviting veterinarians to report their practices in fluid resuscitation and colloid osmotic pressure support, their choice of SC, and perceived adverse effects and contraindications associated with SC use. There were 1,134 respondents from 42 countries, including 46% general practitioners and 38% diplomates. Isotonic crystalloids, HES, and hypertonic saline were chosen by most respondents for fluid resuscitation, and HES by 75% of respondents for colloid osmotic support. Dextran and gelatin were used by some European respondents. Human serum albumin was used more than canine albumin but 45% of respondents, particularly those from Australia and New Zealand, used no albumin product. The majority (70%) of respondents changed their practice regarding SCs in recent years (mostly by limiting their use), largely due to safety concerns. However, only 27% of respondents worked in an institution that had a general policy on SC use. Impaired renal function, coagulopathy, and hypertension were most often considered contraindications; impaired coagulation tests and increased respiratory rate were the most frequently perceived adverse effects. The use of HES remains widespread practice in small animals, regardless of geographic location. Nevertheless, awareness of safety issues and restrictions on the use of SCs imposed in human medicine seems to have prompted a decrease in use of SCs by veterinarians. Given the paucity of evidence regarding efficacy and safety, and differences in cohorts between human and veterinary critical care patients, studies are needed to establish evidence-based guidelines specific for dogs and cats.

Effects of Hydroxyethyl Starch 130/0.4 on Serum Creatinine Concentration and Development of Acute Kidney Injury in Nonazotemic Cats

Background

Hydroxyethyl‐starch (HES) solutions might have renal adverse effects in humans and dogs.

Objective

To determine if administration of 6% HES‐130/0.4 is associated with an increase in serum creatinine concentration and development of acute kidney injury (AKI) in nonazotemic cats.

Animals

A total of 62 critically ill cats; 26 HES exposed and 36 unexposed.

Methods

Retrospective cohort study (2012–2015). Serum creatinine concentrations were recorded and changes in serum creatinine concentrations before exposure (baseline) and 2–10 and 11–90 days, respectively, were determined. Development of AKI was defined as a > 150% increase or >26 μmol/L increase in serum creatinine concentration from baseline. Risk factors, such as HES administration, cumulative volume of HES (mL/kg) and number of days of HES administration leading to development of AKI, and change in serum creatinine were analyzed.

Results

Cats in the HES cohort received a mean volume of 98.5 ± 76.2 mL/kg (range, 8–278 mL/kg) HES over a median of 4 (range, 1–11) days, resulting in a median dose of 20.1 (range, 8–40.5) mL/kg per day. Short‐term %change in serum creatinine concentration (P = 0.40) and development of AKI (P = 0.32) were not significantly different between cohorts. Multivariable logistic regression did not identify HES dose in mL/kg (P = 0.33) and number of days of HES application (P = 0.49) as a risk factor for development of AKI.

Conclusion and Clinical Importance

Hydroxyethyl‐starch administration to critically ill nonazotemic cats seems to be safe. A larger prospective study is required to determine the effect of HES administration at higher dosages and for prolonged time periods.

Prevalence of and risk factors for intraoperative gastroesophageal reflux and postanesthetic vomiting and diarrhea in dogs undergoing general anesthesia

OBJECTIVE

To determine the prevalence of intraoperative gastroesophageal reflux (GER) and postanesthetic vomiting and diarrhea, and to evaluate risk factors associated with these gastrointestinal disorders (GID) in dogs undergoing general anesthesia.

DESIGN

Prospective observational study.

SETTING

University teaching hospital.

ANIMALS

Two hundred thirty-seven client-owned dogs undergoing general inhalant anesthesia for diagnostic or surgical purposes.

INTERVENTIONS

None MEASUREMENTS AND MAIN RESULTS: Patient, surgical, and anesthetic variables, and postanesthetic treatments administered in the immediate postanesthesia period were evaluated in relation to GID using univariate and multivariate logistic regression analysis (P < 0.05). Seventy-nine of the 237 (33.4%) dogs developed GID during the perianesthetic period. The prevalences of GER, vomiting, and diarrhea were 17.3%, 5.5%, and 10.5%, respectively. Intraabdominal surgery (P = 0.016; odds ratio [OR] 2.82, 95% confidence interval [CI]: 1.21-6.62), changes in body position (P = 0.003; OR 3.17, 95% CI: 1.47-6.85), and length of anesthesia (P = 0.052; OR 1.006, 95% CI: 1.000-1.013) were associated with GER. Changes in the ventilation mode during surgery (P = 0.011; OR 6.54, 95% CI: 1.8-23.8), length of anesthesia (P = 0.024; OR 1.001, 95% CI: 1.001-1.020), and rescue synthetic colloid support due to hypotension (P = 0.005; OR 6.9, 95% CI: 1.82-26.3) were positively associated with postanesthetic vomiting. On the contrary, dogs that received acepromazine as premedication were significantly less likely (P < 0.019; OR 12.3, 95% CI: 1.52-100) to vomit. Finally, length of anesthesia, changes in body position, changes in ventilation mode, or hypoxemia during the procedure tended to increase the risk (univariate model) of diarrhea during the recovery phase.

CONCLUSIONS

GID are common in dogs undergoing general anesthesia. Duration and characteristics of the procedure, anesthetic management, and changes in certain patient variables are significant risk factors for the presence of GID in the perioperative period.

Treatment of meloxicam overdose in a dog via therapeutic plasma exchange

OBJECTIVE

To describe the treatment of a meloxicam overdose in a dog with therapeutic plasma exchange (TPE).

CASE SUMMARY

A 6-month-old female Bulldog, presented for routine laparoscopic ovariectomy. Postoperatively the dog received an accidental overdose of meloxicam (1 mg/kg IV [intravenously]). The patient was treated with supportive medical therapy and TPE over 210 minutes achieving 1.2 plasma volume exchanges. During therapy, heparinized blood and effluent samples were collected. Meloxicam concentrations were determined in the samples by high pressure liquid chromatography. Post TPE, the dog continued to receive supportive medical therapy and was discharged 48 hours after the overdose. The dog remained asymptomatic for meloxicam intoxication. Follow-up rechecks at 1 and 6 weeks were unremarkable with no further treatment required.

NEW OR UNIQUE INFORMATION

This report describes the successful use of TPE adjunctively following an acute meloxicam overdose. An 82% reduction of plasma meloxicam concentration was achieved over 210 minutes. Twenty-four hours after therapy, a 47% sustained reduction of plasma meloxicam was measured after redistribution of drug between body compartments.

Changes in Serum Creatinine Concentration and Acute Kidney Injury (AKI) Grade in Dogs Treated with Hydroxyethyl Starch 130/0.4 From 2013 to 2015

BACKGROUND

Hydroxyethyl starch (HES) solutions may cause acute kidney injury (AKI) in humans.

OBJECTIVE

To compare AKI grades in 94 dogs exposed and 90 dogs that were unexposed to 6% HES-130/0.4.

ANIMALS

Dogs receiving 6% HES-130/0.4 (HES cohort) or crystalloids (unexposed cohort) between 2013 and 2015.

METHODS

Historical cohort study. Diagnosis, total cumulative dose and total mL/kg of HES administered, time frame of HES administration and serum creatinine concentrations up to 90 days after initiation of HES treatment were retrospectively reviewed. The AKI grades were retrospectively determined by IRIS guidelines.

RESULTS

Exposed dogs received a median cumulative dose of 69.4 mL/kg (range, 2-429 mL/kg) HES over a median of 4 (range, 1-16) days, resulting in a median dose of 20.7 (range, 2-87) mL/kg/d. Although the cohorts differed in terms of age and diagnosis, AKI grades were not significantly different at the evaluated short- and long-term time points. Results of ordinal logistic regression identified the number of days of HES administration as significantly associated with an increase in AKI grade within 10 days (P = .038), whereas there was no significant association among HES exposure, HES mL/kg/d, and an increase in AKI grade.

CONCLUSIONS AND CLINICAL IMPORTANCE

HES-130/0.4-treated dogs were not more prone to develop AKI than HES-untreated, but the number of HES days was significantly associated with an increase in AKI grade within 10 days post-HES administration. The time frame of HES treatment should be kept short. Prospective, randomized clinical trials are required to assess the effect of HES on renal function in dogs.