Shock Survival Guide

Shock is generally divided into compensatory, early decompensatory, and late decompensatory stages. Cats generally present bradycardic, hypotensive, and hypothermic, often skipping the compensatory stage. Shock may be hypovolemic, cardiogenic, obstructive, or distributive. 

A 4-step fluid resuscitation plan includes determination of stage and cause of shock; selection of fluids for use; decision about endpoint and technique; and reassessment to determine if goals are met, plus treatment of underlying condition.

Crystalloids are water-based solutions containing small molecules (eg, electrolytes, glucose) intended to replace lost fluid. Colloids (eg, dextrans, blood products, hydroxyethyl starches, Oxyglobin) contain large molecular weight particles; use with crystalloids decreases volume needed for resuscitation and amount of fluid lost from the IV space. Colloids are used when there is loss of IV colloids, large volumes of crystalloids are contraindicated, or with a SIRS process.

Endpoints of resuscitation are considered supranormal (normal perfusion parameters, mean arterial pressure (MAP) >90 mm Hg) and hypotensive (normal perfusion parameters, MAP >60 mm Hg). Small volume/hypotensive resuscitation is indicated for hemorrhage; intracranial, heart, or lung disease; and in cats. Indications for large-volume resuscitation include GI disease, hypoadrenocorticism, sepsis/SIRS, and anaphylaxis.

There are numerous potential reasons for poor response to fluid resuscitation. Additional considerations include identifying and treating the underlying condition (eg, in cardiogenic and obstructive shock). Distributive shock can be hard to identify; it is likely the cause in patients that are adequately fluid resuscitated and that have a disease that may result in systemic inflammation or vasodilation.