Perioperative colloid administration: a survey of Spanish anesthesiologists' attitudes

OBJECTIVES: To determine the availability of intravascular fluid volume replacement solutions in Spanish hospitals, to survey the extent of use of colloids by anesthesiologists, to ascertain the possible adverse effects they seek to prevent when using each solution, and to assess their level of knowledge about the subject. MATERIAL AND METHODS: A questionnaire was administered over a period of 6 months (July 2004-January 2005). The questionnaire was available online at www.encuestacoloides.com. The address was distributed by e-mail to anesthesiologists of all the Spanish autonomous communities and published in the Revista Espa?ola de Anestesiología y Reanimación. RESULTS: One hundred forty-two anesthesiologists responded. Crystalloids and colloids were widely available in most hospitals. Hydroxyethyl starch (HES) solutions were the colloids most often used (73%), followed by gelatins (28%). Dextran solutions, on the other hand, were no longer being used. The reasons the respondents gave for using these solutions were related to the time they remained in the vascular system, their greater effect of volume expansion, and the preservation of hemostasis. The most-feared complication was anaphylactic reaction to gelatins and there were concerns about the dose limit for infusion of HES solutions and about hemodynamic instability caused by dextran solutions. Fifty-four percent felt that scientific meetings provide little information about colloids and volume replacement. CONCLUSIONS: There is widespread use of colloids other than dextran along with crystalloids for plasma volume replacement. Spanish anesthesiologists are clear about important concepts related to colloid use. However, a high percentage have doubts about certain fundamental issues. Continuing professional development opportunities related to intravascular fluid replacement therapy should be increased.     

Crystalloid or colloid: Does it matter?

The modern version of the crystalloid-colloid debate has continued for more than 25 years, and a current appraisal of the debate is presented here. Although the effect of crystalloids and colloids on intravascular volume is important, their effect on interstitial fluid volume after hemorrhage and hemorrhagic shock is central to the debate. I f reduced, crystalloids are appropriate as part of the resuscitation regime; if increased, colloid therapy is more logical. A brief review of the distribution of crystalloids and currently used colloids (albumin, polygeline, dextran 70, and hydroxyethyl starch) is presented. The problems of pulmonary and peripheral edema also are presented, as is an appraisal of adverse reactions to colloids together with a cost comparison of crystalloids and colloids. The results of a survey of attitudes at the major Australian anesthetic departments are given, and a personal approach to fluids in resuscitation is outlined.     

The efficacy and safety of colloid resuscitation in the critically ill

Despite evidence from clinical studies and meta-analyses that resuscitation with colloids or crystalloids is equally effective in critically ill patients, and despite reports from high-quality clinical trials and meta-analyses regarding nephrotoxic effects, increased risk of bleeding, and a trend toward higher mortality in these patients after the use of hydroxyethyl starch (HES) solutions, colloids remain popular and the use of HES solutions is increasing worldwide. We investigated the major rationales for colloid use, namely that colloids are more effective plasma expanders than crystalloids, that synthetic colloids are as safe as albumin, that HES solutions have the best risk/benefit profile among the synthetic colloids, and that the third-generation HES 130/0.4 has fewer adverse effects than older starches. Evidence from clinical studies shows that comparable resuscitation is achieved with considerably less crystalloid volumes than frequently suggested, namely, <2-fold the volume of colloids. Albumin is safe in intensive care unit patients except in patients with closed head injury. All synthetic colloids, namely, dextran, gelatin, and HES have dose-related side effects, which are coagulopathy, renal failure, and tissue storage. In patients with severe sepsis, higher doses of HES may be associated with excess mortality. The assumption that third-generation HES 130/0.4 has fewer adverse effects is yet unproven. Clinical trials on HES 130/0.4 have notable shortcomings. Mostly, they were not performed in intensive care unit or emergency department patients, had short observation periods of 24 to 48 hours, used cumulative doses below 1 daily dose limit (50 mL/kg), and used unsuitable control fluids such as other HES solutions or gelatins. In conclusion, the preferred use of colloidal solutions for resuscitation of patients with acute hypovolemia is based on rationales that are not supported by clinical evidence. Synthetic colloids are not superior in critically ill adults and children but must be considered harmful depending on the cumulative dose administered. Safe threshold doses need to be determined in studies in high-risk patients and observation periods of 90 days. Such studies on HES 130/0.4 are still lacking despite its widespread and increasing use. Because there are safer and equally effective alternatives in the form of crystalloids, use of synthetic colloids should be avoided except in the context of clinical studies.     

Intraoperative blood salvage: fluid replacement calculations

Intraoperative blood salvage (IBS) devices are used as adjuncts to blood conservation in spinal surgical procedures of increasing duration, complexity, and total blood loss. We applied existing information about the performance and efficiency of IBS devices together with existing information regarding the distribution of crystalloids and colloids to provide clinicians with guidelines for the prediction of the total blood loss implications of a given volume of IBS return. We also developed guidelines for estimation of the appropriate replacement volumes for the acellular component of blood loss when replacement is undertaken with either isotonic-iso-oncotic colloid or isotonic crystalloid solutions. When average hematocrit during blood loss is between 25% and 30%, total blood loss will be 3.4-4.0 times the volume of the IBS recovery. When replacement is undertaken with colloids or crystalloids, the appropriate replacement volume will be approximately 2.5 and 8.0 (respectively) times the volume of the IBS recovery. These volumes may be larger than have been appreciated by some clinicians.     

Flüssigkeits- und Volumentherapie 2013

Background

After the Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency (EMA) recommended on the 14th June 2013 to suspend marketing authorisations for solutions containing hydroxyethylstarch, a revision process was initiated which is with the European Commission to finally decide on the future of this class of drugs. It is expected that European clinicians will have to live with severe restrictions in the field of intensive care, for the perfusion-related hypovolemia, however – and thus for the perioperative andemergency medical field – hydroxyethyl starch-containing preparations will most likely continue to be available.

The facts

Measurements in humans have shown that the use of isotonic crystalloids in acute hemorrhage at best leads to delayed restitution of blood volume. Iso-oncotic colloids, however, remain to a high percentage intravascularly. Under the postulate that the patient in hypovolemic shock benefits from the timely stabilization of his cardiac preload, isotonic crystalloids therefore appear to be no appropriate alternative to colloids.To date, evidence-based medicine is not capable of advising against a rational colloid for early stabilisation in hypovolemic shock: cardiac preload of most patients in all studies which associated hydroxyethyl starch (HES) with negative effects, was primarily stabilized with natural and artificial colloids, however, outside the study. The use of this therapeutic class for this indication is therefore well established and can hardly be questioned on the basis of scientific data so far. In addition, the recently published CRISTAL trial, which for the first time pictured the phase of initial stabilization of severely shocked patients, showed in around 3,000 ICU patients a significant benefit for the use of colloids over crystalloids in 90-day survival rate.

Conclusion

The data situation for fluid and volume therapy is currently all but trivial. It is good to see that after re-examinating all available data, the European Commission will most possibly take these facts into account and provide a relatively differentiated judgement.     

Transfusion vs. alternative treatment modalities in acute bleeding: a systematic review

BACKGROUND AND METHODS: The practice of transfusion varies a great deal between countries and hospitals. Therefore, a systematic literature review was performed to evaluate the evidence underlying practice of transfusion and alternative treatment modalities in acute bleeding. After a stepwise evaluation, 79 out of 2438 abstracts were approved as the evidence base. RESULTS: Albumin for volume therapy is not better than artificial colloids or crystalloids and may be detrimental in trauma patients. No outcome difference has been proved between artificial colloids and crystalloids. Use of hypertonic solutions remains controversial, as do the concepts of delayed and hypotensive resuscitation. Healthy individuals tolerate acute, normovolaemic anaemia at 5 g haemoglobin/dl, but pre-operative haemoglobin < 6 g/dl gives increased mortality from surgical interventions. Keeping haemoglobin higher than 8-9 g/dl has not been associated with any positive effect on mortality or morbidity, even in patients with cardiovascular disease. The changes induced in erythrocytes by storage may be clinically insignificant. No alternative to erythrocyte transfusion was established. Evidence underlying the practice of thrombocyte and plasma transfusion is scarce. Available evidence on recombinant coagulation factor VIIa is insufficient to define its future role in acute bleedings. Antifibrinolytic drugs in general seem to reduce the need for transfusion. CONCLUSIONS: Intravenous volume replacement and transfusion policies seem largely based on local tradition and expert opinions. As a result of the difficulties in performing controlled studies in patients with acute bleeding and the large number of patients needed to prove effects, other scientific evidence should be sought to better define best practice in this important field.     

Rationale for the Use of Colloids in the Treatment of Shock and Hypovolemia

The question, "Are colloids or crystalloids to be preferred for resuscitation in hypovolemic shock conditions?" is detailed in this review. The effects of these two types of fluid regimes on restitution of circulating blood volume, interstitial rehydration, microvascular blood flow, cellular metabolic recovery and on the incidence of systemic complications such as adult respiratory distress syndrome (ARDS), disseminated intravascular coagulation (DIC) and multiple organ failure are considered. Colloid containing solutions seem superior to crystalloids due to efficient reexpansion of circulating blood volume and enhancement of capillary blood flow. Resuscitation times and thereby the cellular hypoxic insult are considerable reduced while at the same time the formation of excessive tissue oedema is prevented. Colloids do not seem to adversely affect pulmonary function. Dextran has considerable advantages over other types of colloids for the initial shock treatment due to its antithrombotic properties whereby cell aggregability is prevented and the incidence of systemic complications (microembolism syndromes) is convincingly reduced.     

危重患者胶体复苏的有效性和安全性

尽管已有临床研究和荟萃分析的证据表明在危重患者中使用胶体复苏和晶体复苏同样有效,而且有来自于高水平的临床试验和荟萃分析的报告称,使用羟乙基淀粉（hydroxyethylstarch,HES）溶液会出现肾毒性反应、出血风险增加以及死亡率增高的趋势,但胶体治疗依然流行,在世界范围内HES溶液的使用与日俱增。我们主要探讨使用胶体的优势,即胶体是比晶体更为有效的血浆扩容剂、合成胶体与白蛋白一样安全、HES溶液在合成胶体中的风险／效益比最优而且第三代的HES130／0．4比前两代HES不良反应发生率更低等。临床研究表明用晶体溶液达到类似复苏效果的用量比通常认为的要少,即少于2倍胶体用量。白蛋白对于闭合性脑损伤以外的重症监护室（intensiveunitcare,ICU）患者安全性都很高。所有的合成胶体,如右旋糖酐、明胶和HES等都有剂量依赖的副作用,例如凝血障碍、肾衰竭和组织蓄积。在严重脓毒症患者中使用大剂量HES可能导致过高的死亡率。第三代HES130／0．4副作用更小的假设目前还未经证实。有关HES130／0．4的临床试验有着显著缺陷,主要因为并未针对ICU或急诊科患者;仅有24—48小时的短暂观察期;累积使用剂量小于每日剂量限值（50ml／kg）;并且使用了不合适的对照液体如其他HES溶液或明胶。总之,首选胶体溶液对急性血容量减少的患者进行复苏治疗的理论缺乏临床证据的支持。基于给药剂量的限制,合成胶体治疗危重成人及儿童患者的效果并非有益而是有害。安全剂量需通过对高风险患者进行长达90天观察期的研究来确定。尽管HES130／0．4的使用日益增加,但是它还缺乏研究证实。由于有晶体作为等效并且更为安全的选择方案,因此除进行临床研究外应避免使用胶体。     

Indications et place de l'albumine au cours du remplissage vasculaire en traumatologie et en période préopératoire

The use of albumin solutions for volume replacement remains controversial. The last American guidelines recommend the use of albumin for resuscitation in case of a contra-indication of artificial colloids or the requirement of sodium restriction. Recent trials did not show any beneficial effect of albumin on the mortality and morbidity rates. Only an improvement of the rheologic conditions has been found with albumin (and dextran 40), in comparison with starch and gelatin. On the basis of cost-effectiveness considerations, artificial colloids should be at this time favoured over albumin for intravascular expansion, except in pregnant women. For resuscitation, albumin could be used when the recommended upper limit of hydroxyethyl starch vol-ume has been reached and fresh frozen plasma not yet required. During preoperative haemodilution, low molecular weight hydroxyethyl starch has at least the same efficacy as albumin. When a rheologlcal effect is required, albumin could be used.     

Colloid solutions: a clinical update

Albumin, dextran, gelatin, and hydroxyethyl starch (HES) solutions are colloids that efficiently expand the circulating blood volume. The administration of colloids restores the intravascular volume with minimal risk of tissue edema in comparison with crystalloid solutions alone. However, colloids are always given for surgical and critically ill patients. The type of the colloid, volumes applied, aggressiveness of fluid resuscitation, and the volume status at the initial phase of administration determine their clinical responses. The outcome after fluid resuscitation with various colloids in critically ill patients seems to be comparable according to systematic reviews. A randomized, adequately powered clinical trial comparing modern nonprotein colloid to albumin is still lacking. Rapidly degradable HES solutions have good hemodynamic effects, and the risk of adverse renal and coagulation effects, as well as allergic reactions, is minimal. The current investigation has also shown the beneficial effect of HES solution (especially HES 130/0.4) on inflammatory response, postoperative nausea and vomiting, and postoperative outcome. The indication of colloids with an assessment of the degree of hypovolemia and safety profiles should thus be taken into consideration before colloid administration.     

Pharmacology of plasma expanders

Plasma expanders are used to restore the circulating volume of a hypovolaemic patient. Typically, colloids are used to expand the plasma volume, although combinations of hypertonic crystalloid and colloid have recently been used. The currently available colloids vary in their physico-chemical, pharmaco-dynamic and pharmaco-kinetic properties. In particular, they differ in molecular weight, which partly determines their duration of action, and in their ability to expand the plasma volume. Dextran, hydroxyethyl starch and hypertonic colloid solutions improve oxygen flux within the microcirculation. Despite their benefits, the use of dextran and high molecular weight starches is limited by their negative impact on coagulation. In addition, these macro-molecules may also induce acute renal failure in susceptible patients. Current research focuses on the development of artificial oxygen-carriers as plasma expanders. These substances, which include modified stromal-free haemoglobin and perfluorocarbon emulsions, are undergoing clinical trials.     

Pharmacology of plasma expanders

Plasma expanders are used to restore the circulating volume of a hypovolaemic patient. Typically, colloids are used to expand the plasma volume, although combinations of hypertonic crystalloid and colloid have recently been used. The currently available colloids vary in their physicochemical, pharmacodynamics and pharmacokinetic properties. In particular, they differ in molecular weight, which partly determines their duration of action, and in their ability to expand the plasma volume. Dextran, hydroxyethyl starch and hypertonic colloid solutions improve oxygen flux within the microcirculation. Despite their benefits, the use of dextran and high-molecular-weight starches is limited by their negative impact on coagulation. In addition, these macro-molecules may also induce acute renal failure in susceptible patients. Current research focuses on the development of artificial oxygen carriers as plasma expanders. These substances, which include modified stromal-free haemoglobin and perfluorocarbon emulsions, are undergoing clinical trials.     

Crystalloids versus colloids for resuscitation in shock

The optimal composition of fluid for volume resuscitation in critically ill patients has been the subject of controversy for decades. Clinicians are faced with several options, including crystalloid solutions of varying tonicity, several colloid preparations (albumin and others), and blood products. Some of these solutions may be differentially distributed between the intra- and extravascular, and intra- and extracellular compartments, accounting for a variety of physiological effects. Two recently published meta-analyses concluded that colloids afford no survival benefit in critically ill patients compared with crystalloids. Albumin infusion may be of more value in patients with cirrhosis, or in those at high risk of acute renal failure. Additional randomized trials will be needed to establish the optimal composition and volume of colloid or crystalloid solutions for resuscitation in shock.     

Methods of reducing blood loss and non-blood substitutes

A variety of techniques can aid the anaesthetist in reducing requirements for perioperative blood products. These include careful preoperative assessment of the patient, and employing techniques during surgery which reduce the blood pressure and help preserve the normal haemostatic mechanism. If the level to which haematocrit will be permitted to decrease is decided, then physiological crystalloid and/or colloid solutions may be used to maintain circulating volume. Where large volumes of fluids are required cardiac filling pressures should be monitored because of the complex nature of the fluid shifts which occur. There is no evidence that any one fluid (physiological crystalloids, colloids) is better than any other in terms of the incidence of perioperative morbidity.     

Tromboelastometria rotacional na avaliação dos efeitos de cristaloides balanceados,hidroxietilamido e gelatina na coagulação: estudo randômico

Background and objectivesModern crystalloid and colloid solutions are balanced solutions which are increasingly used in perioperative period. However, studies investigating their negative effect on whole blood coagulation are missing, and vivid debate is going on about which solution has the minimal coagulopathy effect. The aim of our study was to assess the effect of modern fluid solutions on whole blood coagulation using rotational thromboelastometry.MethodsBlood samples were obtained from 30 patients during knee arthroscopy before and after administration of 500 mL of crystalloid, Hydroxyethyl Starch and gelatin according to the randomization. Rotational thromboelastometry (Extem, Intem and Fibtem tests) was used to assess negative effect of fluid solutions on whole blood coagulation.ResultsIn Extem test, the initiation phase of fibrin clot formation represented by CT parameter was not influenced by any fluid solution (p > 0.05). The speed of clot formation represented by CFT and α angle was impaired by Hydroxyethyl Starch and gelatin but not by crystalloids (p < 0.05). The strength of formatted coagulum represented by MCF parameter was impaired both in Extem and Fibtem test by HES and in Fibtem also by crystalloids (p < 0.05). Intem test was not negatively influenced by any crystalloid or colloid solution in any parameter (p > 0.05).ConclusionExtem test appears to be sensitive to coagulopathy effect of modern colloids and crystalloids. Hydroxyethyl starch has the most obvious negative effect on clot formation followed by gelatin and finally by crystalloids. Intem test seems to be insensitive to adverse effect of modern colloids and crystalloids.     

Colloids versus crystalloids as priming solutions for cardiopulmonary bypass: a meta-analysis of prospective, randomised clinical trials

Using Cochrane methodology a review was performed of prospective randomized clinical trials comparing colloidal pump priming solutions for cardiopulmonary bypass. Dextrans were not considered. Database searches from 1966 through December 2002 delivered 265 articles. Seventeen studies finally met the eligibility criteria involving 997 patients. Summary odds ratio estimates from the 5 studies reporting mortality were 1.46 (n = 326; 95%-Confidence-Interval: .55 to 3.85; p = .49) for crystalloids against colloids and .74 (n = 150; 95%-Confidence-Interval: .17 to 3.36; p = .49) for albumin versus synthetic colloids. Most commonly used outcome measures further included postoperative blood loss, platelet-count, fluid-balance and, colloid osmotic pressures from which Standardized Mean Differences (SMD) and their 95%-Confidence-Interval (95%CI) were extracted. Colloids produced significantly higher oncotic pressures and less positive fluid-balances. Although across 9 studies postoperative bleeding between colloids and crystalloids did not differ (n = 663; SMD: -.03, 95%CI: -.18 to .12; p = .69), platelet counts significantly favoured crystalloids (n = 465; SMD: -.42; 95%CI: -.68 to -.16; p = .00). However, compared to albumin platelet counts were significantly disfavoured only by starches (n = 321; SMD: -.55; 95%CI: -.77 to -.32; p = .00). To conclude, using mere crystalloids produced more pronounced positive fluid balances and their avoidance as a single pump-prime component can be suggested. Since albumin is not necessarily associated with better outcomes and is more expensive, it is hard to continue its use. However, there is still insufficient evidence available to allow definitive conclusions.     

New mathematical model for the correct prediction of the exchangeable blood volume during acute normovolemic hemodilution

BACKGROUND: The blood volume that has to be exchanged for crystalloids and/or colloids during acute normovolemic hemodilution (ANH) in order to reach a preset target hemoglobin concentration (hb) is usually predicted by the Bourke and Smith formula developed in 1974. This formula systematically overestimates the 'true' exchangeable blood volume (EBV), a fact that may potentially endanger patients because the target hb will be missed and the normovolemic anemia might turn out to be more severe than a priori intended. Our objective was to develop a more accurate mathematical model of hemodilution kinetics and to validate this new model in animals and in patients undergoing ANH. METHODS: Twenty-two anesthetized beagle dogs and 18 patients under balanced anesthesia underwent isovolemic hemodilution with hydroxyethyl starch (HAES 6%, 200 000) to a target hb of 7 g dl-1 or 9 g dl-1, respectively. Exchangeable blood volume predicted by use of the different mathematical models was compared with the blood volume actually exchanged to meet the preset target hb. RESULTS: Calculation of EBV by the Bourke and Smith formula (EBVB + S) systematically overestimated the volume actually exchanged (overestimation: dogs 15%, patients 20%), whereas our new iterative model predicted EBV (EBViterative) more reliably (overestimation: dogs 1%, patients 8%). In both cases EBVB + S differed significantly from the EBViterative. CONCLUSION: Exchangeable blood volume is predicted more accurately by the new iterative model than by the Bourke and Smith formula. The iterative model leads to an improvement in patient safety and provides a physiologically adequate basis for future studies investigating the efficacy of ANH in reducing allogenic blood transfusions.     

Volume replacement and microhemodynamic changes in polytrauma

Though fluid administration is one of the most basic concepts in resuscitation, there is ongoing controversy and continuing research on the definition of the ideal fluid for resuscitation of trauma and hemorrhage and for intraoperative volume support. In general, crystalloids and colloids, as well as blood, blood substitutes and oxygen therapeutics, are available. This report briefly revisits the physiological mechanisms underlying resuscitation with crystalloids and colloids, emphasizing colloid-supplemented resuscitation with hypertonic saline. Finally, potential applications of oxygen therapeutics are briefly considered.     

Place de l'albumine dans les œdèmes pulmonaires et dans le choc septique, à l'exclusion du remplissage vasculaire

Patients with septic shock deserve a global approach. Intravascular volume loading is part of the treatment. However several questions remain open: what are the respective contributions of volume expansion and vaso-active drugs in the restoration of blood pressure and increase of cardiac output, which volumes and type of solutions should be used, which pulmonary capillary wedge pressure should be targetted, and which evaluation criteria are the most appropriate? Few experimental and clinical studies provide evidence of a superiority of colloids over crystalloids, although none of them has documented a reduction of mortality, lenght of stay in ICU or duration of mechanical ventilation. There are no data support-ing a superiority of albumin over artifical colloids, which are also much cheaper. Moreover, hydroxyethylstarch could have promising properties in case of increased capillary permeability. In summary and in agreement with the North American consensus conference, albumin should not be recommended for the treatment of septic shock, whether associated with non cardiogenic pulmonary oedema or not.     

Anesthesiologic problems and specifics in the management of severe pelvic injuries]

There is a close relationship between trauma of the pelvis, hemorrhagic shock, microcirculation disturbances and multiple organ failure. Of primary importance are the treatment of pain, early intubation, artificial ventilation, protection against heat loss and replacement of massive blood loss. Contrary to conventional volume replacement by electrolyte solutions, the author favors the administration of colloids, especially the new concept of "small volume resuscitation," i.e., the rapid infusion of a mixture of hypertonic saline solution and hyperoncotic dextran. Although there are limitations, the central venous and pulmonary arterial pressure reflect the volume balance of the circulation. The oxygen partial pressure of mixed venous blood, more or less reflecting the global oxygen supply state of the organism, can be measured only by means of a pulmonary artery catheter. The outcome depends greatly on optimization of the oxygen supply to a patient in shock whose oxygen needs are remarkably increased. Therapy should be aimed at keeping the arterial oxygen tension above 150 mmHg, increasing the cardiac index to 50% above normal, and stabilizing the hemoglobin concentration at an individually optimized value.