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Fluid Therapy

Journal Club: Crystalloids vs. Colloids in Septic Shock — Does the Debate Still Matter?

A journal club discussion of the CRISTAL and CHEST trials, their implications for veterinary fluid selection, and why the crystalloid-first approach remains defensible in small animal emergency practice.

2 min read

This month's journal club covered a classic controversy that refuses to stay settled: the choice between crystalloids and colloids for initial resuscitation in septic shock. We reviewed the CRISTAL trial, CHEST (Crystalloid versus Hydroxyethyl Starch Trial), and a 2024 meta-analysis examining colloid use specifically in small animal sepsis models.

What the Human Trials Show

The CHEST trial, published in the New England Journal of Medicine, randomized over 7000 ICU patients to receive either 6% HES (hydroxyethyl starch) or 0.9% saline for resuscitation. The HES group had a significantly higher rate of renal replacement therapy and a trend toward increased 90-day mortality. The trial effectively ended the use of synthetic colloids in most human ICUs.

CRISTAL was more nuanced—comparing all colloids (including albumin) against crystalloids—and found no significant mortality difference, though colloid patients had better 28-day organ failure-free days. The trial didn't reshape practice largely because of heterogeneity in colloid type and concerns about HES safety.

The Veterinary Picture

Here is where things get interesting. Hydroxyethyl starch products (Hetastarch, Vetstarch) remained in widespread use in veterinary medicine long after CHEST changed human practice. Regulatory status, cost, and the absence of comparable veterinary RCTs sustained their use. A 2023 systematic review in JVECC found no survival benefit for colloids over crystalloids in dogs with septic shock, though studies were small and retrospective.

Our group reached the following consensus after discussion:

  1. Crystalloid-first is appropriate for initial resuscitation in most septic dogs and cats. The evidence for harm with synthetic colloids is real; the evidence for benefit is not compelling.

  2. Human albumin at 4–5% may have a role in hypoalbuminemic septic patients (albumin < 1.5 g/dL), but cost and availability limit use to select cases.

  3. The debate over colloid versus crystalloid distracts from more impactful decisions: source control timing, vasopressor initiation, antibiotic spectrum, and lactate clearance monitoring.

One Dissenting View

One of our residents made the fair point that colloids offer a volume-sparing effect that crystalloids don't match, and that fluid overload in septic shock is an underappreciated cause of organ dysfunction. This is true, and the pivot to balanced, pragmatic small-volume resuscitation rather than large-volume crystalloid loading is a legitimate response—but the solution is restrained crystalloid use plus vasopressors, not synthetic colloids.

We'll revisit this topic when the results of the DOMINO-Vet trial (expected 2026) become available.