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Fluid responsiveness: is it that simple?

Fluid therapy is the most commonly used initial therapeutic intervention in treatment of shock states (e.g. in hypovolemic and distributive types of shock). The approach to fluid resuscitation evolved over the last few decades. For instance, we no longer start with a full “shock dose” of fluids (60-90 ml/kg), and instead, an incremental 10-20 ml/kg boluses are preferred with frequent reassessment of the end-goal perfusion parameters. The standard therapeutic targets include improving heart rate, pulse quality, capillary refill time (CRT), non-invasive or invasive blood pressure and mucous membrane color.

But, how reliable is this approach in assessment of fluid responsiveness? Today, I will explore available evidence and diagnostic tools that can be utilized in evaluation of fluid responsiveness in veterinary and human patients.

Hypercalcemia in dogs with Addison’s disease

Hypoadrenocorticism (i.e., Addison’s disease) is an important differential for hypercalcemia. The etiology of hypercalcemia in hypoadrenocorticism in dogs is unclear. Hall et. al (JVIM 2023) wanted to find out the prevalence and factors associated with hypercalcemia in this population of dogs by performing a multicenter retrospective observational study at the 4 UK referral hospitals. They analyzed data from 110 dogs and found that about 34.5% of the dogs with Addison’s had either total and/or ionized hypercalcemia. The odds of hypercalcemia were increased (P < .05) in dogs with classic Addison’s (deficient in both mineralo- and glucocorticoids), higher serum creatinine, and higher serum albumin. The odds of ionized hypercalcemia were increased (P < .05) with reduced serum potassium concentration and younger age.

Lung and Pleural Space Ultrasound

Lung and pleural space point-of-care ultrasound is usually performed in sternal recumbency unless a dog cannot tolerate this position. In this scenario, the patient can be positioned in right or left lateral recumbency to evaluate all lung fields. The Pleural and Lung Protocol (PLUS) is my preferred method to evaluate the pleural space and lung parenchyma (Boysen et al. 2022).

Metabolic alkalosis in animals with upper GI obstruction

If you are presented with an acutely vomiting canine or feline patient who happened to have a metabolic alkalosis on the blood gas analysis, an upper gastrointestinal (GI) obstruction should be suspected. Lozano et al. (Texas A&M University, JSAP 2023) recently published a study that looked at the prevalence of various acid-base and electrolyte disorders in this population of dogs. A total of 115 dogs were included in the study, with 22% of dogs showing either a simple metabolic alkalosis or a mixed metabolic alkalosis before surgery. While 37% of dogs had a normal acid–base status on presentation.

Should you recommend euthanizing canine patients with spontaneous hemoperitoneum based on CT results alone?

As emergency veterinarians, one of the most critical decisions we face is whether to recommend humane euthanasia in canine patients with spontaneous (non-coagulopathic) hemoperitoneum based solely on CT results. A recent study shed light on the limitations of CT imaging in distinguishing between benign and malignant lesions in such cases (Parry et al. JVECC 2023). Understanding the study’s findings is crucial for making well-informed decisions and providing optimal care for our canine patients. In this blog post, we will explore the study’s results, particularly the concerning frequency of benign lesions being misinterpreted as malignant, and discuss the implications for our decision-making process.