Synthetic colloids |
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categories . The systematic reviews provide us with high-level evidence indicating that HES in general causes renal impairment as measured as increased use of renal replacement therapy and increased mortality . None of the systematic reviews found evidence to support the notion that tetrastarch has a better safety profile than other HES solutions . In fact , the two largest trials ( CHEST and the 6S trial ) compared tetrastarch to crystalloid solutions and found increased use of renal replacement therapy and even increased mortality in one trial ( the 6S trial ). 3 , 4
The results of Colloids Compared to Crystalloids in Fluid Resuscitation of Critically Ill Patients ( CRYSTAL ) trial ( NCT00318942 ) are likely to be published soon . In this trial , ICU patients with shock were randomised to open-labelled resuscitation with HES 130 , albumin or gelatin versus any crystalloid solution . The results will add to the overall evidence base , but the open-label design and the use of different fluids in both the colloid and crystalloid arms may hamper the interpretation of the results .
HES in peri- and post-operative care In general , trials of tetrastarch in surgery are relatively small , with short-term follow-up only and high risk of bias . 9 , 11 Therefore , these trials cannot inform us about effects and side-effects of HES beyond the first few days . After the retraction of the trials by Boldt , there are only few trials comparing the potency of tetrastarch versus crystalloid in the surgical setting . Therefore , the potency difference remains largely unknown .
As the harmful effects of HES may occur late , at least in patients with sepsis , 3 , 12 the lack of long-term safety data on tetrastarch in surgery is a dilemma for the clinicians who continue to use HES in these patients . Even though acute kidney injury is unlike in low-risk patients , it is problematic that the rate and severity of itching is unknown after the use of tetrastarch in patients undergoing elective surgery . There are recently up-dated systematic reviews on the use of tetrastarch in surgical patients , 13 , 14 but these included healthy persons and trials with other HES solutions as comparator hampering the interpretation of the results . In addition , the recommendations of the Cochrane Collaboration were not followed in these reviews and they were sponsored by industry , both of which increase the risk of bias .
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Gelatin Compared to HES , gelatin was used less frequently in the worldwide point prevalence study . 1 In some countries , such as the UK and Hong Hong , gelatin was the most frequently used colloid .
The gelatins are polypeptides produced by hydrolysis of collagen , most often from cattle bone . The products are now modified by urea cross-linking or succinylation . The gelatins used in fluid therapy have a molecular weight around 20 kDa with a wide range and are excreted by the kidneys without prior metabolism . Gelatins have lower molecular weight than both HES and albumin , but there are no high-quality trial data showing gelatins potency as plasma expander compared to crystalloids .
Overall , the evidence for the use of gelatin is poor and no large , randomised trials have been done to assess the efficacy and harm of this colloid class . A recent systematic review identified that the trials comparing gelatin with crystalloid or albumin solutions were small , done in elective surgery mainly , and had follow-up time of less than 24h . 15 The side-effects of gelatin are comparable to those observed with HES , including impairment of kidney function and haemostasis . Thus , overall beneficial effects of gelatin are unlikely in critically ill patients , a notion supported by data from the meta-analysis 15 and from a before-and-after study in a single ICU . 16 In the latter study , gelatin was associated with acute kidney injury in patients with severe sepsis . Along this line , the European Society of Intensive Care Medicine ( ESICM ) Task Force on colloids recommended that gelatin is only used in the context of randomised clinical trials . 6
Conclusions The evidence to support that resuscitation with colloids may result in less fluid use and improved haemodynamics is sparse . In contrast , it is clear from several high-quality trials and meta-analyses in critically ill patients that treatment with tetrastarches causes impaired renal function and haemostasis and may even increase mortality . Therefore , HES should not be used in these patients . Gelatin is considerable less studied , but the overall effects of colloids are likely to be minor compared to crystalloids and the side-effects of gelatins comparable to starch . Following this , the use of synthetic
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colloids should be limited in all patient categories . l
References
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11 . Hartog CS , Kohl M , Reinhart K . A systematic review of third-generation hydroxyethyl starch ( HES 130 / 0.4 ) in resuscitation : safety not adequately addressed . Anesth Analg 2011 ; 112:635 – 45 .
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16 . Bayer O et al Effects of fluid resuscitation with synthetic colloids or crystalloids alone on shock reversal , fluid balance , and patient outcomes in patients with severe sepsis : a prospective sequential analysis . Crit Care Med 2012 ; 40:2543 – 51 .
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