Effect of Colloids Versus Crystalloids on Heart Mechanics: a Double-blind Cross Over Randomized Trial

The debate over whether to use colloid or crystalloid solutions for fluid resuscitationis still ongoing. Colloid solutions consist of large molecules that generally cannot pass through healthy capillary membranes, whereas crystalloid solutions contain ions that easily move from the intravascular space to the interstitial compartment. Therefore, it is traditionally argued that colloids are more effective at expanding intravascular volume, with a suggested ratio of 1:3 compared to crystalloids. However, there is currently limited evidence to suggest that resuscitation with one type of fluid is more effective or safer than t he other. Despite these theoretically advantageousphysiological properties, colloids have not demonstrated a clear hemodynamic benefit over crystalloids. We hypothesized that these unexpected discrepancies may be attributed to different mechanical heart responses.