Point-of-care viscoelastic coagulation monitor parameters in Amazon parrots (Amazona spp.).

OBJECTIVE: To evaluate the feasibility of the point-of-care viscoelastic coagulation monitor (VCM) in Amazon parrots (Amazona spp.) and describe the parameters with fresh whole-blood samples in healthy Amazon parrots. DESIGN: A total of 18 Amazon parrots were enrolled. Physical examinations, a CBC, and a biochemistry profile, including bile acids, were performed on all parrots. VCM tracings were obtained at the time of venipuncture for baseline laboratory work. MEASUREMENTS AND MAIN RESULTS: The median clot time was 2102 seconds (range: 38.6-3599 s), median clot formation time was 929 seconds (range: 21.4-1711 s), median alpha angle was 20 (range: 6-67), and the median maximum clot formation was 8.5 (range: 0-36). The median lysis index at 30 minutes (LI30) was 100 (range: 98-100), and the median lysis index at 45 minutes (LI45) was 100 (range: 90-100). Of 18 samples, alpha angles were not reported in 7 samples, LI30 was not reported in 10 samples, and LI45 was not reported in 12 samples. Of the qualitative curves, 6 reflected normal mammalian curves, and the remainder were consistent with a hypocoaguable state. CONCLUSIONS: The results were markedly variable, with the majority of VCM tracings being hypocoagulable in comparison with reference intervals established for dogs and cats. Using these protocols, the VCM is not reliable in Amazon parrots. Future areas of investigation include altering the temperature during sample analysis, the use of activators, or an exchange of clotting reagents for an extrinsic pathway activator, which may contribute to the success of this device in avian species.

The effect of position and frequency of mixing on canine packed red blood cell units during storage.

OBJECTIVE: Hemolysis is an indicator of storage lesion that occurs in stored packed red blood cells (pRBCs) over time. Intermittent mixing of red blood cells in the additive solutions may be beneficial but may also result in iatrogenic injury. Position of units in storage may also affect the quality of the pRBCs. This prospective study was designed to evaluate hemolytic effect of mixing frequency and storage position on canine pRBCs over a period of 28 days. DESIGN: Prospective in vitro study SETTING: Private practice referral hospital with an internal blood bank ANIMALS: Thirty-two healthy prescreened dogs enrolled in a volunteer blood banking program INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: A total of 160 samples were evaluated. Forty canine pRBC units were split into 4 daughter bags and stored in varying positions with different mixing frequencies. Samples were stored upright and mixed daily, upright and mixed weekly, horizontally and mixed daily, or horizontally and mixed weekly for a period of 28 days. At days 0, 7, 14, and 28, samples from the units were analyzed to calculate percent hemolysis. No differences were found in any hemolytic indicators investigated (total hemoglobin, free plasma hemoglobin, and packed cell volume) until day 28 in all test groups. Canine pRBCs stored upright and mixed weekly or stored horizontally and mixed weekly resulted in less hemolysis and free plasma hemoglobin when compared to units stored horizontally and mixed daily only at day 28. CONCLUSIONS: Statistically significant hemolysis was not evident amongst canine pRBC groups less than 28 days old suggesting that positioning and mixing frequency was irrelevant until day 28. Beyond 28 days despite the presence of hemolysis, no definitive recommendation could be made with respect to best practice for storage position or mixing frequency of stored canine pRBCs.

In vitro iatrogenic hemolysis of canine packed red blood cells during various rapid transfusion techniques.

OBJECTIVE: To evaluate which rapid blood administration technique causes the least iatrogenic hemolysis in canine packed red blood cells (pRBCs) as determined by plasma free hemoglobin (fHb) and percent hemolysis (% hemolysis). DESIGN: Prospective in vitro randomized study. SETTING: Private referral center. ANIMALS: None. INTERVENTIONS: Thirteen units of canine pRBCs were divided equally into 5 aliquots, resulting in 65 trials. The aliquots of each unit were subjected to the following administration techniques: gravity-driven (control), an infusion pump at maximal rate, application of a pressure bag, manual compression, and syringe bolus. Plasma fHb and % hemolysis were recorded before and after each trial. Rate of administration (mL/s) was calculated for each method. MEASUREMENTS AND MAIN RESULTS: Compared to the control, there were no significant increases in % hemolysis or plasma fHb noted among any of the trial methods. The manual compression and syringe bolus methods resulted in the fastest transfusion rates, whereas the infusion pump was not faster than the gravity-driven method. Despite a storage time of ≤14 days, 15% of pRBC units had unsuitable (>0.8%) hemolysis before even being subjected to the trials. CONCLUSIONS: Commonly used rapid infusion techniques in small animal transfusion medicine do not cause significant iatrogenic hemolysis of canine pRBCs in vitro, although a significant risk is present in stored blood. This suggests that if an expedited transfusion is needed, any method described in this study could be considered, although stored pRBCs should be tested for unsuitable levels of hemolysis prior to transfusion.

Visual inspection of stored canine blood for hemolysis compared with measured plasma-free hemoglobin to assess suitability for transfusion.

Canine blood was visually inspected for hemolysis and compared with the Food and Drug Administration's standard of less than 1% hemolysis as measured by plasma-free hemoglobin. This was the basis for deciding to transfuse or dispose of stored canine blood. Free hemoglobin was measured in stored red blood cell units and compared to a calculated 1% hemolysis. Veterinarians and technicians determined if they would transfuse units based on visual inspection for hemolysis. Their evaluation was compared to the calculated hemolysis cutoff. The evaluations of veterinarians and technicians were significantly different from the mathematically derived cutoff. The technicians' visual assessments of the usability of samples were significantly different from those of the veterinarians: technicians more frequently judged the sample as unusable. Experienced veterinary personnel both over- and under-estimate the degree of hemolysis in stored canine RBCs. We recommend objective analysis of the amount of free hemoglobin in stored blood prior to transfusion.

Inspection visuelle du sang canin entreposé pour l'hémolyse comparativement à la mesure de l'hémoglobine libre pour évaluer sa qualité pour la transfusion. Du sang canin a été inspecté visuellement pour l'hémolyse et comparé à la norme de la Food and Drug Administration de moins de 1 % d'hémolyse mesurée par l'hémoglobine libre dans le plasma. Ce paramètre a été utilisé pour décider soit de faire la transfusion ou de jeter le sang canin entreposé. L'hémoglobine libre a été mesurée dans les unités de globules rouges entreposées et comparée à une hémolyse calculée à 1 %. Les vétérinaires et les techniciens ont déterminé s'ils effectueraient une transfusion des unités en se basant sur une inspection visuelle pour l'hémolyse. Leur évaluation a été comparée au seuil de coupure calculé pour l'hémolyse. Les évaluations des vétérinaires et des techniciens étaient significativement différentes du seuil dérivé des calculs mathématiques. Les évaluations visuelles des techniciens pour déterminer l'utilisabilité des échantillons étaient significativement différentes de celles des vétérinaires : les techniciens jugeaient plus fréquemment que les échantillons étaient inutilisables. Le personnel vétérinaire d'expérience surestime et sous-estime le degré d'hémolyse dans les globules rouges canins entreposés. Nous recommandons une analyse objective de la quantité d'hémoglobine libre dans le sang entreposé avant la transfusion.(Traduit par Isabelle Vallières).

An Unusual Case of Portal Hypertension Secondary to Primary Hypoplasia of the Portal Vein.

Primary hypoplasia of the portal vein with secondary portal hypertension and acquired portosystemic collateral circulation is infrequently reported in the veterinary literature. Diagnosis of this condition requires documentation of abnormal hepatocellular function, the lack of intrahepatic or extrahepatic macroscopic congenital portosystemic shunts, and liver histopathology demonstrating portal hypoperfusion in the absence of hepatic inflammation or nodular regeneration. Due to a perceived poor prognosis, many patients with this condition are euthanized; however, those that are spared can be medically managed, in some cases for years. This case report describes the diagnosis and management of a patient with primary hypoplasia of the portal vein and secondary portal hypertension that presented with the severe but typical clinical manifestations of ascites and hepatic encephalopathy, normal liver enzyme concentrations, and normal serum bile acid concentrations.

Central venous pressure: principles, measurement, and interpretation.

Central venous pressure (CVP), an estimate of right atrial pressure, has been used to assess cardiac preload and volume status in critically ill patients, assist in the diagnosis of right-sided heart failure, and guide fluid resuscitation. It is determined by the interaction between cardiac function and venous return. CVP measurements are relatively easy to obtain; however, because of the complex relationship between CVP, cardiac output, and the vascular system, they may be difficult to interpret. This article reviews the physiologic principles of CVP, indications for its use, technical aspects and pitfalls of CVP measurements, and interpretation of the information obtained.