Colloids Yes or No? - a “Gretchen Question” Answered

Abstract

Colloid solutions, both natural and synthetic, had been widely accepted as having superior volume expanding effects than crystalloids. Synthetic colloid solutions were previously considered at least as effective as natural colloids, as well as being cheaper and easily available. As a result, synthetic colloids (and HES in particular) were the preferred resuscitation fluid in many countries. In the past decade, several cascading events have called into question their efficacy and revealed their harmful effects. In 2013, the medicines authorities placed substantial restrictions on HES administration in people which has resulted in an overall decrease in their use. Whether natural colloids (such as albumin-containing solutions) should replace synthetic colloids remains inconclusive based on the current evidence. Albumin seems to be safer than synthetic colloids in people, but clear evidence of a positive effect on survival is still lacking. Furthermore, species-specific albumin is not widely available, while xenotransfusions with human serum albumin have known side effects. Veterinary data on the safety and efficacy of synthetic and natural colloids is limited to mostly retrospective evaluations or experimental studies with small numbers of patients (mainly dogs). Large, prospective, randomized, long-term outcome-oriented studies are lacking. This review focuses on advantages and disadvantages of synthetic and natural colloids in veterinary medicine. Adopting human guidelines is weighed against the particularities of our specific patient populations, including the risk–benefit ratio and lack of alternatives available in human medicine.

Low‐Fouling Zwitterionic Polymeric Colloids as Resuscitation Fluids for Hemorrhagic Shock

“…We also tested the 6 wt% HES (130/0.4) as a positive control, which is typically used in clinical formulation and is known to cause severe coagulopathy. [ 7,9–11,33 ] As shown in Figure 6A–C, as expected, the commercial 6 wt% HES (130/0.4) caused a significant delay in clotting time (CT) and clotting formation time (CFT), lower maximum clot firmness (MCF), and much higher maximal lysis (ML). Although 1.6 wt% HES did not adversely affect the onset of clotting or the clot strength, it resulted in significantly higher ML, indicating undesirable interference.…”

“…[ 7,9–11 ] Similar side effects by other colloids including dextran or modified gelatin have also been reported. [ 7,12 ] As a result, current guidelines have restricted the use of colloids, favoring the use of crystalloids instead. [ 13 ] Clearly, it remains highly desirable to develop new colloidal volume expanders with improved safety and efficacy profiles to fill an important therapeutic gap in resuscitation and critical care.…”

“…[ 3 ] Due to this oncotic effect, colloids are considered more effective volume expanders for resuscitation from HS. [ 3,7,8 ]…”

Assessment of Hydroxyethyl Starch (6% HES 130/0.4) Kidney Storage in Critically Ill Dogs: A Post-mortem Prospective Study

“…Several underlying mechanisms for HES-induced AKI are described as follows: colloid-induced increases in plasma colloid-osmotic pressure and subsequent decreases in filtration pressure and glomerular filtration rate (“hyperoncotic AKI”); accumulation of HES-molecules in tubular epithelial cell lysosomes leading to renal epithelial dysfunction; tubular hyperviscosity and colloid precipitation; forming of occluding casts; and ON ( 1 ). These mechanisms can be reversible, and function may be restored ( 12 ); however, such factors may also be a first step in the development of irreversible cell lesions.…”

“…Hydroxyethyl starch (HES) solutions belong to the class of synthetic colloids and comprise modified maize or potato starch suspended in an isotonic crystalloid solution ( 1 ). Since its introduction in the 1970's, several HES products with varying physicochemical properties, such as molecular weight (MW) and degree and pattern of hydroxyethylation, were developed.…”