Accuracy of Crit-Line® monitors in predicting hematocrit and change in blood volume of dogs during hemodialysis.

BACKGROUND: Ultrafiltration (UF) is an extracorporeal technique for treating fluid overload and is monitored with noninvasive blood volume monitors. HYPOTHESIS/OBJECTIVES: The primary objective was to determine the accuracy of Crit-Line® III and IV noninvasive blood volume monitors to estimate canine packed cell volume (PCV) and changes in blood volume during UF. A secondary aim was to determine accuracy of targeted ultrafiltration rates (UFR) compared to calculated delivered UFR. METHODS: An ex vivo study with a single Phoenix® X36 platform and canine packed red blood cells (pRBC) was performed. Through dilution and UF, clinically applicable PCV values were obtained and compared to Crit-Line® hematocrit (Hct). Blood volume was constantly measured and compared to targeted UFR. Systematic and proportional bias were calculated using a Bayes method. RESULTS: Crit-Line® III and IV reported Hct was significantly lower than PCV (n = 140, median 26%, range, 8%-50%) when PCV was >25% and >30%, respectively. Crit-Line® III and IV calculated change in blood volume (ΔBV%) was significantly different from measured blood volume changes at ΔBV% ±20% and >-20%, respectively. Comparing targeted and delivered UFR (mL/h), less than targeted UFR was removed at UFR100 through UFR400 and UFR0 adding volume. CONCLUSIONS AND CLINICAL IMPORTANCE: Crit-Line® III and IV monitors provide accurate estimates of canine PCV and UF volume change within specific ranges and are useful in monitoring canine UF and hemodialysis. Veterinary hemodialysis services should evaluate individual machines for UFR inaccuracies, which can meaningfully affect small animals.

Iodinated non-ionic contrast medium does not inhibit Escherichia coli growth in ex vivo inoculated canine urine.

OBJECTIVE: To investigate the effect of iohexol on standardized quantitative urine culture results in dogs. The authors hypothesized that the presence of iohexol in inoculated urine samples would result in lower bacterial concentrations (CFU/mL) and, therefore, decrease culture sensitivity. SAMPLE: Urine samples were aseptically collected during cystoscopy from a single client-owned dog untreated with antimicrobials. PROCEDURES: An experimental controlled study. The urine sample was divided into 38 aliquots (0.5 mL each) that were used as negative controls or inoculated with an equal amount of Escherichia coli (105 CFU/mL). Different volumes (0.1 and 0.5 mL) of contrast or saline were added to the aliquots and quantitative culture results were compared. Two different incubation times between the preparation of aliquots and culture were evaluated (15 minutes and 24 hours). RESULTS: All aliquots from samples inoculated with E. coli (positive controls and iohexol-group) had the same reported quantitative result (104 CFU/mL). No growth was reported for the negative controls. Iohexol did not show any anti-E. coli properties in canine urine cultures for dilutions up to 1:2 contrast:urine and concentrations up to 120 mgI/mL. No difference was reported when iohexol was incubated with inoculated urine for 15 minutes or 24 hours. CLINICAL RELEVANCE: Based on the experimental in vitro conditions described, administration of iohexol before the collection of urine during urologic procedures does not negatively impact the isolation and growth of E. coli.

A Therapeutic Extracorporeal Device for Specific Removal of Pathologic Asymmetric Dimethylarginine from the Blood.

INTRODUCTION: Blood levels of uremic toxin, asymmetric dimethylarginine (ADMA), are strongly associated with mortality in sepsis, renal failure, and cardiovascular and renal disease patients. METHODS: An extracorporeal approach to reduce pathological ADMA was developed. The dimethylarginine dimethylaminohydrolase (DDAH) was immobilized on agarose beads to prepare a cartridge. The efficacy of cartridge for ADMA lowering in blood was investigated. RESULTS: The DDAH beads and cartridge reduced ADMA from solution or plasma. The magnitude of ADMA removal was dependent on the quantity of DDAH linked to the beads and the flow rate. When tested in association with plasmapheresis, the DDAH-cartridge was highly effective in ADMA removal from the blood and improved the arginine/ADMA ratio in a pig model. CONCLUSION: A new, safe, and effective extracorporeal approach to lower ADMA was developed which may have application in improving outcomes in patients with vascular complications and risk of mortality associated with high ADMA.

Ultrasonographic diagnosis of a hair foreign body in the urinary bladder of a dog.

A 13-year-old male neutered mixed-breed dog with a history of gallbladder mucocele and urolithiasis was evaluated by ultrasound. Two hyperechoic, linear foreign bodies with no distal acoustic shadowing were detected in the urinary bladder and urethra. Following the ultrasound examination, the patient underwent cystoscopy, and two single hairs were found and successfully retrieved. Considering that urinary bladder foreign bodies may be a source for urinary tract infection and can act as a nidus for urocystolith formation, removal is recommended. This is the first published report describing ultrasonographic diagnosis of a hair foreign body in the canine urinary bladder and urethra.

Transcutaneous glomerular filtration rate measurement in a canine animal model of chronic kidney disease.

INTRODUCTION: Quantitative assessment of renal function by measurement of glomerular filtration rate (GFR) is an important part of safety and efficacy evaluation in preclinical drug development. Existing methods are often time consuming, imprecise and associated with animal burden. Here we describe the comparison between GFR determinations with sinistrin (PS-GFR) and fluorescence-labelled sinistrin-application and its transcutaneous detection (TD-GFR) in a large animal model of chronic kidney disease (CKD). METHODS: TD-GFR measurements compared to a standard method using i.v. sinistrin were performed in a canine model. Animals were treated with one-sided renal wrapping (RW) followed by renal artery occlusion (RO). Biomarker and remote hemodynamic measurements were performed. Plasma sinistrin in comparison to transcutaneous derived GFR data were determined during healthy conditions, after RW and RW+RO. RESULTS: RW alone did not led to any significant changes in renal function, neither with PS-GFR nor TD-GFR. Additional RO showed a rise in blood pressure (+68.0mmHg), plasma urea (+28.8mmol/l), creatinine (+224,4µmol/l) and symmetric dimethylarginine (SDMA™; +12.6µg/dl). Plasma sinistrin derived data confirmed the expected drop (-44.7%, p<0.0001) in GFR. The calculated transcutaneous determined Fluorescein Isothiocyanate (FITC)-sinistrin GFR showed no differences to plasma sinistrin GFR at all times. Both methods were equaly sensitive to diagnose renal dysfunction in the affected animals. DISCUSSION: Renal function assessment using TD-GFR is a valid method to improve preclinical drug discovery and development. Furthermore, TD-GFR method offers advantages in terms of reduced need for blood sampling and thus decreasing animal burden compared to standard procedures.

Use of a Microsoft Excel based add-in program to calculate plasma sinistrin clearance by a two-compartment model analysis in dogs.

Assessment of renal function by means of plasma clearance of a suitable marker has become standard procedure for estimation of glomerular filtration rate (GFR). Sinistrin, a polyfructan solely cleared by the kidney, is often used for this purpose. Pharmacokinetic modeling using adequate software is necessary to calculate disappearance rate and half-life of sinistrin. The purpose of this study was to describe the use of a Microsoft excel based add-in program to calculate plasma sinistrin clearance, as well as additional pharmacokinetic parameters such as transfer rates (k), half-life (t1/2) and volume of distribution (Vss) for sinistrin in dogs with varying degrees of renal function.