Hydroxyethyl starch 130/0.4 (6%) and succinylated gelatine (4%) interfere with refractometry in dogs with haemorrhagic shock

OBJECTIVE

To determine if low molecular weight synthetic colloid fluids administered to dogs interfere with refractometric estimates of total plasma protein (TPPr) and urine osmolality (UOsm).

STUDY DESIGN

Experimental study.

ANIMALS

Eighteen healthy Greyhound dogs.

METHODS

Anaesthetized Greyhounds subjected to haemorrhage for 60 minutes were given 80 mL kg^-1 of Plasma-Lyte 148 (CRYST), or 20 mL kg^-1 of hydroxyethyl starch 130/0.4 (HES) or succinylated gelatine (GELO) (n = 6 per group) intravenously over 20 minutes. Refractometric (TPPr) and biuret total plasma protein (TPPb) were measured before haemorrhage (Baseline), at end of shock (Shock), immediately (T20), then 40 minutes (T60), 100 minutes (T120) and 160 minutes (T180) after fluid administration. Urine specific gravity (USG) and UOsm were measured at all time points except T20. Estimated UOsm (eUOsm) was calculated from USG. Bias and limits of agreement (LOA) for TPPr versus TPPb, and eUOsm versus UOsm were calculated at each time point.

RESULTS

For dogs given CRYST and GELO, median TPPr and TPPb decreased in parallel, with a small consistent TPP bias (CRYST range of bias, 0.38-0.67 g dL^-1; GELO range of bias, 0.42-0.58 g dL^-1). Dogs given HES showed divergence between median TPPr and TPPb after T20, with a peak bias at T20 of 1.62 g dL^-1 (LOA 1.29-1.95). Dogs given HES and GELO had markedly increased USG [HES peak median USG at T180 of 1.119 (Q1-Q3 1.103-1.122); GELO peak median USG at T120 of 1.114 (Q1-Q3 1.082-1.119)], with large increases in bias between eUOsm and UOsm [HES peak bias at T60 of 2995 mOsm kg^-1 (LOA 2032-3958 mOsm kg^-1); GELO peak bias at T120 of 2465 mOsm kg^-1 (LOA 940-3990 mOsm kg^-1)].

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of HES and GELO to dogs with haemorrhagic shock interferes with refractometric measurements for at least 3 hours after administration.

Stability of osmolality in previously frozen canine serum and urine samples

BACKGROUND

The measurement of osmolality is of interest in several clinical conditions and has been investigated in multiple veterinary studies. However, the stability of osmolality over time in frozen canine serum and urine has not been established.

OBJECTIVES

The purpose of this study was to determine the stability of osmolality in canine serum and urine stored frozen at -20°C and -80°C up to 90 days, and to assess the effect of storage temperature on osmolality measurement.

METHODS

Serum and urine samples collected from 5 healthy Greyhound dogs were aliquoted and stored at -20°C and -80°C until measurement. Osmolality, assessed by freezing-point depression, was measured at 0, 7, 14, 30, and 90 days of storage.

RESULTS

For both serum and urine, osmolality at day 7 was not statistically different from day 0, but osmolality at days 14, 30, and 90 was significantly lower than at day 0. There was no significant effect of storage temperature on serum osmolality. However, the osmolality of urine samples stored at -20°C was slightly, but significantly lower than the osmolality of those stored at -80°C.

CONCLUSIONS

Osmolality measurement in the serum and urine of healthy dogs appears to be stable for at least 7 days in frozen samples. The small changes observed after day 7 are unlikely to be relevant for individual patients, but could have implications in research study protocols.

Natural and Synthetic Colloids in Veterinary Medicine

This review article covers basic physiology underlying the clinical use of natural and artificial colloids as well as provide practice recommendations. It also touches on the recent scrutiny of these products in human medicine and how this may have an effect on their use in veterinary medicine.

Central diabetes insipidus following cardiopulmonary arrest in a dog

OBJECTIVE

To describe a clinical case of transient central diabetes insipidus (CDI) occurring post cardiopulmonary arrest (CPA) in a dog.

CASE SUMMARY

An 8-week-old dog presented for intensive care after successful resuscitation following CPA. The patient exhibited neurologic deficits at initial presentation and over the following days developed marked polyuria, isosthenuria, and low urine osmolality. Treatment with synthetic vasopressin resulted in a reduction in urine output, increase in urine specific gravity (>50%), and increase in urine osmolality, suggesting a diagnosis of partial CDI. Clinical signs resolved over the following weeks and treatment was discontinued.

NEW OR UNIQUE INFORMATION PROVIDED

CPA has been described as a cause of ischemic injury to the pituitary gland resulting in CDI in people. To the authors' knowledge, this is the first report of a dog developing transient partial CDI following CPA and successful resuscitation.

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

OBJECTIVE

To review and summarize the pharmacokinetics and pharmacodynamics of hydroxyethyl starch (HES), as well as reported risks and benefits of HES infusion, and to provide administration and monitoring recommendations for HES use in dogs and cats.

DATA SOURCES

Veterinary and human peer-reviewed medical literature, including scientific reviews, clinical and laboratory research articles, and authors' clinical experience.

SUMMARY

HES solutions are the most frequently used synthetic colloid plasma volume expanders in human and veterinary medicine. The majority of research in human medicine has focused on the adverse effects of HES infusion, with emphasis on acute kidney injury and coagulation derangements. The studies often differ in or fail to report factors, such as the type, amount, interval, and concentration of HES administered; the patient population studied; or concurrent fluids administered. Currently, there is no definitive clinical evidence that the reported adverse effects of HES use in human medicine occur in veterinary species. There is little information available on HES administration techniques or simultaneous administration of additional fluids in human and veterinary medicine. The rationale for HES use in small animals has been largely extrapolated from human medical studies and guidelines. A controlled approach to intravenous fluid resuscitation using crystalloid and HES volumes titrated to reach desired resuscitation end point parameters is outlined for small animal practitioners.

CONCLUSION

The extrapolation of data from human studies directly to small animals should be done with the knowledge that there may be species variations and different pharmacokinetics with different HES solutions. Veterinary reports indicate that bolus and continuous rate infusions of 6% hetastarch solutions at moderate doses are well tolerated in feline and canine subjects. Further research in domesticated species is necessary to better define and expand the knowledge regarding use of HES solutions in small animal medicine.