Janet Aldrich

The effect of hetastarch (670/0.75) on urine specific gravity and osmolality in the dog.

BACKGROUND Urine specific gravity (USG) is used clinically to estimate urine osmolality (UOsm). Although USG has been shown to have a linear correlation with UOsm in dogs, the relationship is altered when there are significant numbers of high molecular weight (MW) molecules in the urine. HYPOTHESIS USG would no longer predict UOsm in dogs given intravenous hetastarch (670/0.75)(HES). ANIMALS Eight healthy employee-owned adult dogs. METHODS Prospective, controlled experimental study. USG and UOsm were measured every 30 minutes from t=0 minutes to t=360 minutes. Dogs were administered 20 mL/kg of either NaCl 0.9% (control group, n=4) or HES (treatment group, n=8) IV over 1 hour starting at t=90 minutes. RESULTS There was a decrease in UOsm in both groups starting at t=120 minutes and continuing for the study duration, and there was no significant difference in UOsm between treatment and control groups across all time points. There was an appropriate decrease in USG from t=120 minutes for the control group. In the treatment group, USG increased significantly at t=120 minutes (P= .0006), t=150 minutes (P= .0002), and t=180 minutes (P= .0044). The largest increase in USG occurred at t=150 minutes with a mean USG of 1.070 +/- 0.021 (range 1.038-1.104). CONCLUSIONS AND CLINICAL IMPORTANCE Urine specific gravity should not be used to estimate urine solute concentration in dogs following the administration of 20 mL/kg of HES. In a clinical setting, the evaluation of USG following this dose of HES may lead to an overestimation of urine concentration.

Successful ventilatory management of post‐anesthetic airway collapse and hypoxemia in a dog

Objective: To report a life-threatening complication (airway collapse) associated with a common procedure (anesthesia) and to describe its successful management. Case Summary: A dog without pre-existing signs of respiratory disease developed hypoxemia and severe atelectasis in the post-anesthetic recovery period and was demonstrated, by bronchoscopic examination, to have severe airway collapse. Mechanical ventilation was used to re-expand collapsed lung units and to prevent re-collapse. A ventilation strategy designed to minimize airway and alveolar trauma was used. The dog was successfully weaned from the ventilator and made a full recovery. Unique Information Provided: Acute, severe hypoxemia due to airway collapse occurred in the post-operative period in a dog with no signs of pre-existing respiratory disease. The dog was successfully managed with short-term mechanical ventilation. High frequency jet ventilation was used for a diagnostic bronchoscopy.