A Systematic Review of the Comparative Safety of Colloids

Year in review 2007: Critical Care--multiple organ failure and sepsis

Several research papers published in Critical Care throughout 2007 examined the pathogenesis, diagnosis, treatment and prognosis of sepsis and multiorgan failure. The present review summarizes the findings and implications of the papers published on sepsis and multiorgan failure and places the research in the context of other work in the field.

Safety of HES 130/0.4 (Voluven(R)) in patients with preoperative renal dysfunction undergoing abdominal aortic surgery: a prospective, randomized, controlled, parallel-group multicentre trial

BACKGROUND AND OBJECTIVE

Patients with impaired renal function are at risk of developing renal dysfunction after abdominal aortic surgery. This study investigated the safety profile of a recent medium-molecular-weight hydroxyethyl starch (HES) preparation with a low molar substitution (HES 130/0.4) in this sensitive patient group.

METHODS

Sixty-five patients were randomly allocated to receive either 6% hydroxyethyl starch (Voluven); n = 32) or 3% gelatin (Plasmion); n = 33) for perioperative volume substitution. At baseline, renal function was impaired in all study patients as indicated by a measured creatinine clearance < 80 mL min(-1). The main renal safety parameter was the peak increase in serum creatinine up to day 6 after surgery.

RESULTS

Both treatment groups were compared for non-inferiority (pre-defined non-inferiority range hydroxyethyl starch < gelatin + 17.68 micromol L(-1) or 0.2 mg dL(-1). Other renal safety parameters included minimum postoperative creatinine clearance, incidence of oliguria and adverse events of the renal system. Baseline characteristics, surgical procedures and the mean total infusion volume were comparable. Non-inferiority of hydroxyethyl starch vs. gelatin could be shown by means of the appropriate non-parametric one-sided 95% CI for the difference hydroxyethyl starch-gelatin [-infinity, 11 micromol L(-1)]. Oliguria was encountered in three patients of the hydroxyethyl starch and four of the gelatin treatment group. One patient receiving gelatin required dialysis secondary to surgical complications. Two patients of each treatment group died.

CONCLUSION

As we found no drug-related adverse effects of hydroxyethyl starch on renal function, we conclude that the choice of the colloid had no impact on renal safety parameters and outcome in patients with decreased renal function undergoing elective abdominal aortic surgery.

The influence of volume management on outcome

PURPOSE OF REVIEW

Fluid (volume) therapy is an integral component in the management of critically ill patients and fluid management may influence outcome. There is much controversy, however, about the type, timing and amount of fluid therapy. Here, we discuss the evidence available to guide such choices.

RECENT FINDINGS

Fluid therapy is widely endorsed for resuscitation of critically ill patients across a range of conditions. Yet, the approach to fluid therapy is subject to substantial variation in clinical practice. Emerging data show that the choice, timing and amount of fluid therapy may affect clinical outcomes. Synthetic colloids may increase the risk of acute kidney injury. Albumin may benefit hypoalbuminemic patients with sepsis and acute lung injury but may worsen outcome in traumatic brain injury. Early administration of fluid therapy in sepsis may improve survival but may be unnecessary in patients with penetrating trauma. Later fluid therapy in acute lung injury patients will increase the duration of ventilator dependence without achieving better survival. A positive cumulative balance likely contributes to increased morbidity and mortality after major surgery.

SUMMARY

Emerging evidence shows that choice, timing and amount of fluid therapy affect outcome. Future studies need to focus on these aspects of fluid therapy by means of larger, more rigorous and blinded controlled trials.

Systematic review of randomized clinical trials on the use of hydroxyethyl starch for fluid management in sepsis

Background

Patients with sepsis typically require large resuscitation volumes, but the optimal type of fluid remains unclear. The aim of this systematic review was to evaluate current evidence on the effectiveness and safety of hydroxyethyl starch for fluid management in sepsis.

Methods

Computer searches of MEDLINE, EMBASE and the Cochrane Library were performed using search terms that included hydroxyethyl starch; hetastarch; shock, septic; sepsis; randomized controlled trials; and random allocation. Additional methods were examination of reference lists and hand searching. Randomized clinical trials comparing hydroxyethyl starch with other fluids in patients with sepsis were selected. Data were extracted on numbers of patients randomized, specific indication, fluid regimen, follow-up, endpoints, hydroxyethyl starch volume infused and duration of administration, and major study findings.

Results

Twelve randomized trials involving a total of 1062 patients were included. Ten trials (83%) were acute studies with observation periods of 5 days or less, most frequently assessing cardiorespiratory and hemodynamic variables. Two trials were designed as outcome studies with follow-up for 34 and 90 days, respectively. Hydroxyethyl starch increased the incidence of acute renal failure compared both with gelatin (odds ratio, 2.57; 95% confidence interval, 1.13–5.83) and crystalloid (odds ratio, 1.81; 95% confidence interval, 1.22–2.71). In the largest and most recent trial a trend was observed toward increased overall mortality among hydroxyethyl starch recipients (odds ratio, 1.35; 95% confidence interval, 0.94–1.95), and mortality was higher (p < 0.001) in patients receiving > 22 mL·kg^-1 hydroxyethyl starch per day than lower doses.

Conclusion

Hydroxyethyl starch increases the risk of acute renal failure among patients with sepsis and may also reduce the probability of survival. While the evidence reviewed cannot necessarily be applied to other clinical indications, hydroxyethyl starch should be avoided in sepsis.

Intensive insulin therapy and pentastarch resuscitation in severe sepsis

BACKGROUND

The role of intensive insulin therapy in patients with severe sepsis is uncertain. Fluid resuscitation improves survival among patients with septic shock, but evidence is lacking to support the choice of either crystalloids or colloids.

METHODS

In a multicenter, two-by-two factorial trial, we randomly assigned patients with severe sepsis to receive either intensive insulin therapy to maintain euglycemia or conventional insulin therapy and either 10% pentastarch, a low-molecular-weight hydroxyethyl starch (HES 200/0.5), or modified Ringer's lactate for fluid resuscitation. The rate of death at 28 days and the mean score for organ failure were coprimary end points.

RESULTS

The trial was stopped early for safety reasons. Among 537 patients who could be evaluated, the mean morning blood glucose level was lower in the intensive-therapy group (112 mg per deciliter [6.2 mmol per liter]) than in the conventional-therapy group (151 mg per deciliter [8.4 mmol per liter], P<0.001). However, at 28 days, there was no significant difference between the two groups in the rate of death or the mean score for organ failure. The rate of severe hypoglycemia (glucose level, < or = 40 mg per deciliter [2.2 mmol per liter]) was higher in the intensive-therapy group than in the conventional-therapy group (17.0% vs. 4.1%, P<0.001), as was the rate of serious adverse events (10.9% vs. 5.2%, P=0.01). HES therapy was associated with higher rates of acute renal failure and renal-replacement therapy than was Ringer's lactate.

CONCLUSIONS

The use of intensive insulin therapy placed critically ill patients with sepsis at increased risk for serious adverse events related to hypoglycemia. As used in this study, HES was harmful, and its toxicity increased with accumulating doses. (ClinicalTrials.gov number, NCT00135473.)

Scandinavian Clinical Practice Guidelines on the diagnosis, management and follow-up of anaphylaxis during anaesthesia

The present approach to the diagnosis, management and follow-up of anaphylaxis during anaesthesia varies in the Scandinavian countries. The main purpose of these Scandinavian Clinical Practice Guidelines is to increase the awareness about anaphylaxis during anaesthesia amongst anaesthesiologists. It is hoped that increased focus on the subject will lead to prompt diagnosis, rapid and correct treatment, and standardised management of patients with anaphylactic reactions during anaesthesia across Scandinavia. The recommendations are based on the best available evidence in the literature, which, owing to the rare and unforeseeable nature of anaphylaxis, mainly includes case series and expert opinion (grade of evidence IV and V). These guidelines include an overview of the epidemiology of anaphylactic reactions during anaesthesia. A treatment algorithm is suggested, with emphasis on the incremental titration of adrenaline (epinephrine) and fluid therapy as first-line treatment. Recommendations for primary and secondary follow-up are given, bearing in mind that there are variations in geography and resources in the different countries. A list of National Centres from which anaesthesiologists can seek advice concerning follow-up procedures is provided. In addition, an algorithm is included with advice on how to manage patients with previous suspected anaphylaxis during anaesthesia. Lastly, Appendix 2 provides an overview of the incidence, mechanisms and possibilities for follow-up for some common drug groups.

Response of healthy dogs to infusions of human serum albumin

OBJECTIVE

To evaluate the clinical and immunologic response in healthy dogs to infusions of human serum albumin (HSA).

ANIMALS

9 healthy purpose-bred mixed-breed dogs.

PROCEDURES

Each dog was administered a 25% HSA solution once or twice. Various physical examination and laboratory variables were serially evaluated. Antibody against HSA was assayed before and after infusion by use of an ELISA. Intradermal testing was also conducted. A repeated-measures ANOVA or Friedman repeated-measures ANOVA on ranks was used to compare results for the variables.

RESULTS

Adverse clinical reactions were observed after the first or second infusion in 3 dogs. Anaphylactoid reactions were observed in 1 of 9 dogs during the first infusion and in 2 of 2 dogs administered a second infusion. Two dogs developed severe edema and urticaria 6 or 7 days after an initial infusion. All dogs developed anti-HSA antibodies. Positive responses for ID tests were observed in 8 of 9 dogs. Short-term increases were detected in blood protein, total bilirubin, and calcium concentrations after HSA infusion. Serum cholesterol concentrations and platelet counts decreased after HSA infusion.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of HSA resulted in profound reactions in 2 of 9 dogs administered a single infusion and in 2 of 2 dogs administered a second infusion. This indicates that there is risk of life-threatening adverse reactions to HSA infusion in healthy dogs.

Pulmonary function is better preserved in pigs when acute normovolemic hemodilution is achieved with hydroxyethyl starch versus lactated Ringer's solution

Acute normovolemic hemodilution (ANH) has been proposed to decrease the need for allogenic blood transfusion. Consequently, great amounts of fluids are necessary to maintain hemodynamics during and after blood removal. The aim of this experiment was to evaluate the oxygenation, respiratory compliance, and lung structure during ANH performed with lactated Ringer's solution and hydroxyethyl starch (HES). Gas exchange, extravascular lung water, intrathoracic blood volume, serum osmolality, respiratory mechanics, and optical and electronic microscopy of lung biopsies were evaluated. Animals were randomized into three groups: CTL (control, n = 9), HES (HES 6% 200/0.5, n = 9), and LR (lactated Ringer's solution, n = 9). Animals in groups HES and LR underwent ANH to reach a preestablished hematocrit of around 15%. The removed blood was replaced with HES in a proportion of 1:1 and with lactated Ringer's solution 3:1. The LR group demonstrated a tendency for a marked time-dependence decrease in compliance (P = 0.013 in T2; P = 0.008 in T3) and in Pao2/fraction of inspired oxygen (Fio2) ratio (P = 0.033 in T2) as well as an increase in (A-a) Grad O2 (P = 0.037 in T2). Extravascular lung water and intrathoracic blood volume did not present any significant variation among the groups. In contrast, serum osmolality presented a significant decline in animals hemodiluted with lactated Ringer's solution. Optical and electronic microscopy of lungs biopsies revealed moderate to serious collapses and basement membrane enlargement in LR group. In this kind of experimental model, ANH with 6% HES (200/0.5) seems to preserve lung structure better as evidenced by maintenance of oxygenation indexes and respiratory compliance when compared with that in the Ringer's solution hemodiluted group.

Comparison of three perioperative fluid regimes for laparoscopic donor nephrectomy : A prospective randomized dose-finding study

Background

Pneumoperitoneum (PP), as used for laparoscopic procedures, impairs stroke volume, renal blood flow, glomerular filtration rate and urine output. This study investigated whether perioperative fluid management can abolish these negative effects of PP on hemodynamics.

Methods

Twenty-one patients undergoing laparoscopic donor nephrectomy (LDN) were randomized into three groups: group 1 received overnight infusion and received a bolus of colloid before induction of anesthesia, followed by a bolus just before PP; group 2 received overnight infusion and a colloid bolus before anesthesia; group 3 served as controls and received only infusion during operation. All three groups received the same total amount of crystalloids and colloids until nephrectomy. Data analysis of the donor included; mean arterial pressure (MAP), stroke volume (SV), left ventricular ejection time (LVETc), perioperative urine output and renal function measured as the creatinine clearance (CrCl) until one-year post-operative.

Results

SV was significantly higher in group 1 compared to controls for all measurements. In the control group SV significantly decreased after changing from the supine to lateral position whereas there was no change in SV in both pre-hydrated groups. In all groups, MAP decreased after induction of anesthesia, and restored to pre-anesthetic values during PP. CrCl decreased in the control group during PP, but not in the other groups. From two days postoperative, CrCl was comparable between the three study groups.

Conclusion

Overnight infusion and a bolus of colloid just before PP attenuate hemodynamic compromise from PP.

Gelatin colloids in the resuscitation of trauma

To date, the specific role of gelatins in trauma resuscitation remains under-investigated. Their adverse affects are well described and relate principally to the provocation of allergic responses whilst their influence upon haemostasis is relatively benign in comparison to the other colloids. However, their benefits are only sparsely documented and the evidence to choose one gelatin over another virtually non-existent. As knowledge of the microcirculatory dysfunction inherent in the shocked state increases, the role of the gelatins in trauma resuscitation is being increasing sidelined by other colloids--notably the starches. Their role beyond a basic resuscitation tool is now uncertain.

Prediction of hypotension during spinal anesthesia for cesarean section and its relation to the effect of crystalloid or colloid preload

BACKGROUND

If parturients prone to develop caval compression in the supine position were identified before delivery, this might be a method of predicting hypotension during caesarean section under spinal anesthesia. Colloid preloading is superior to crystalloid in reducing the risk for spinal anesthetic-induced hypotension. It is postulated that parturients preoperatively susceptible to the supine position would benefit the most from colloid preloading.

METHODS

Fifty-five healthy parturients scheduled for elective cesarean section under spinal anesthesia were preoperatively investigated with a supine stress test with measurement of maternal heart rate, blood pressure, right uterine artery pulsatility index and symptoms in the left lateral and supine positions. They were then randomized to receive a colloid or crystalloid preload before anesthesia.

RESULTS

The stress test was positive, indicating a reduced tolerance to the supine position, in 36%. The sensitivity and specificity of the stress test for clinically significant hypotension (symptomatic hypotension) for patients randomized to the crystalloid group (n=25) were 69 and 92% respectively. Patients with a positive stress test receiving a crystalloid preload showed a higher frequency of hypotension compared to all other groups, 90% vs. 33%, (P=0.003) and also a greater need for ephedrine, mean dose (SD): 20.0 (9.7) vs. 8.4 (9.0) mg (P=0.002).

CONCLUSIONS

Pregnant women with a positive preoperative supine stress test constitute a subset at increased risk for clinically significant hypotension during cesarean delivery under spinal anesthesia. These women seem more likely to benefit from prophylactic colloid solution than women with a negative stress test.

Effects of hydroxyethyl starch administration on renal function in critically ill patients

BACKGROUND

The influence of hydroxyethyl starch (HES) solutions on renal function is controversial. We investigated the effect of HES administration on renal function in critically ill patients enrolled in a large multicentre observational European study.

METHODS

All adult patients admitted to the 198 participating intensive care units (ICUs) during a 15-day period were enrolled. Prospectively collected data included daily fluid administration, urine output, sequential organ failure assessment (SOFA) score, serum creatinine levels, and the need for renal replacement therapy (RRT) during the ICU stay.

RESULTS

Of 3147 patients, 1075 (34%) received HES. Patients who received HES were older [mean (SD): 62 (SD 17) vs 60 (18) years, P = 0.022], more likely to be surgical admissions, had a higher incidence of haematological malignancy and heart failure, higher SAPS II [40.0 (17.0) vs 34.7 (16.9), P < 0.001] and SOFA [6.2 (3.7) vs 5.0 (3.9), P < 0.001] scores, and less likely to be receiving RRT (2 vs 4%, P < 0.001) than those who did not receive HES. The renal SOFA score increased significantly over the ICU stay independent of the type of fluid administered. Although more patients who received HES needed RRT than non-HES patients (11 vs 9%, P = 0.006), HES administration was not associated with an increased risk for subsequent RRT in a multivariable analysis [odds ratio (OR): 0.417, 95% confidence interval (CI): 0.05-3.27, P = 0.406]. Sepsis (OR: 2.03, 95% CI: 1.37-3.02, P < 0.001), cardiovascular failure (OR: 6.88, 95% CI: 4.49-10.56, P < 0.001), haematological cancer (OR: 2.83, 95% CI: 1.28-6.25, P = 0.01), and baseline renal SOFA scores > 1 (P < 0.01 for renal SOFA 2, 3, and 4 with renal SOFA = 0 as a reference) were all associated with a higher need for RRT.

CONCLUSIONS

In this observational study, haematological cancer, the presence of sepsis, cardiovascular failure, and baseline renal function as assessed by the SOFA score were independent risk factors for the subsequent need for RRT in the ICU. The administration of HES had no influence on renal function or the need for RRT in the ICU.

[Hemorrhagic shock]

Hemorrhagic shock is a condition produced by rapid and significant loss of blood which lead to hemodynamic instability, decreases in oxygen delivery, decreased tissue perfusion, cellular hypoxia, organ damage and can be rapidly fatal. Despite improved understanding of the pathophysiology and significant advances in technology, it remains a serious problem associated with high morbidity and mortality. Early treatment is essential but is hampered by the fact that signs and symptoms of shock appear only after the state of shock is well establish and the compensatory mechanisms have started to fail. The primary goal is to stop the bleeding and restore the intravascular volume. This review addresses the pathophysiology and treatment of haemorrhagic shock.

Fluid resuscitation in liposuction: a prospective analysis of infiltrate-to-total aspirate ratios lower than used for the superwet technique

BACKGROUND

Fluid management during liposuction appears to as much an art as it is a science. Because of different infiltration practices such as wet, superwet, and tumescent techniques, different fluid management guidelines are required. This has assumed greater significance as surgeons have undertaken aspirations with larger volumes (>/=4 l) and the potential complications of hypovolemia and fluid overload have materialized.

METHODS

In this prospective study, 580 consecutive patients underwent liposuction using an average infiltrate-to-total aspirate ratio of 0.38. For all the patients, noninvasive hemodynamic parameters were assessed to evaluate a clinically based guideline for fluid management in liposuction.

RESULTS

The average infiltrate-to-total aspirate ratio was 0.38 +/- 0.18 (range, 0.24-0.8). Total urine output was 1.63 ml/kg per hour (range, 1.06-3.4 ml/kg/h). The average postoperative heart rate was 92.16 beats/min, and the average postoperative mean blood pressure readings were 70.41 mmHg. The intraoperative fluid ratio, defined as the ratio of intraoperative intravenous fluid plus subcutaneous infiltrate to total aspirate, ranged from 0.98 to 2.1 (average, 1.25). The average percentage of body weight aspirated was 5.2% (range, 1.76-7.02%)

CONCLUSION

This article presents a safe fluid management guideline based on experimental data from 580 patients who underwent liposuction using average infiltration-to-aspirate rates of 0.38. However, the calculated volumes from all the formulas should be viewed as educated guesses of the appropriate fluid load, and clinical judgment is essential.

Fluid resuscitation increases inflammatory gene transcription after traumatic injury

BACKGROUND

The debate continues over type and quantity of fluid to administer for resuscitation after traumatic injury. This study aimed to examine effects of resuscitation with lactated Ringer's (LR) and Hextend (HEX) on the inflammatory response after uncontrolled hemorrhagic shock (UHS).

METHODS

There were 38 swine randomized. Control swine were anesthetized and killed. Sham swine underwent laparotomy, splenectomy, and 2 hours of anesthesia. UHS swine received a grade V liver injury after laparotomy and splenectomy and were randomized to no fluid (NF) resuscitation or to blinded resuscitation 30 minutes after injury with LR or HEX. Fluids were infused as needed to maintain baseline blood pressure for 90 minutes. Lung tissue mRNA levels of interleukin-6 (IL-6), granulocyte colony stimulating factor (G-CSF), and tumor necrosis factor alpha (TNF-alpha) were determined. Lung sections were examined for neutrophils (PMNs) sequestered within alveolar walls.

RESULTS

All UHS animals survived and initial blood loss was similar between groups. Mean arterial pressures (MAPs) were similar for all UHS animals until resuscitation was initiated. MAPs of resuscitated animals remained similar and were significantly higher than MAPs of the NF animals. Sequestered PMNs were equally elevated in all UHS animals. Cytokine analysis showed increased IL-6, G-CSF, and TNF-alpha gene transcription in resuscitated swine compared with NF swine. LR and HEX resuscitated swine tissue mRNA levels showed no differences.

CONCLUSIONS

Fluid resuscitation after solid organ injury and uncontrolled hemorrhage results in greater proinflammatory gene transcription than no resuscitation. LR and HEX resuscitation have equivalent effects on indices of inflammation in the lungs.

Renal impact of fluid management with colloids: a comparative review

BACKGROUND AND OBJECTIVES

Colloids such as hydroxyethyl starch (HES), gelatin, dextran and albumin are useful for maintaining renal perfusion and function. The comparative renal effects of colloids have not been previously reviewed.

METHODS

Computer searches of the MEDLINE and EMBASE bibliographic databases and the Cochrane Library were conducted using the search terms: colloids; hetastarch; gelatin; dextrans; serum albumin; kidney failure; cardiac surgical procedures; and kidney transplantation. Relevant studies were also sought through hand searching and examination of reference lists. Results of identified studies were qualitatively summarized with account taken for potential confounding factors.

RESULTS

The three artificial colloids HES, gelatin and dextran all exhibited troublesome renal side-effects. Randomized trials have demonstrated adverse renal effects of HES in sepsis and surgery. Undesirable renal effects are common to all available HES solutions regardless of molecular weight, substitution or C2/C6 ratio. While some of its effects may be less severe than those of HES, gelatin also can adversely affect the kidney. A negative renal impact of dextran is well-established, although this colloid is now less extensively used than formerly. As the normal endogenous colloid, albumin exhibits a wide margin of renal safety, although albumin overdose needs to be avoided. Albumin also appears to exert protective effects on the kidney such as inhibition of apoptosis and scavenging of reactive oxygen species.

CONCLUSIONS

Colloids display important differences in their actions on the kidney. These contrasting renal effects should be considered in making fluid management decisions.

A single bolus of 3% hypertonic saline with 6% dextran provides optimal initial resuscitation after uncontrolled hemorrhagic shock

BACKGROUND

The optimal fluid for early resuscitation of hemorrhagic shock would restore perfusion without increasing blood loss, hypothermia, acidosis, or coagulopathy. This study examined effects of a single bolus of hypertonic saline (HTS) with or without (+/-) dextran (D) after uncontrolled hemorrhage (UH) and determined optimal fluid composition.

METHODS

Fifty swine were anesthetized and underwent invasive line placement, celiotomy, splenectomy, suprapubic catheterization, and grade V liver injury. After 30 minutes of UH, blinded fluid resuscitation was initiated with a 250-mL bolus. Animals were randomized to five groups: normal saline (NS), 3% HTS (3%), 3% HTS/6% D (3% D), 7.5% HTS (7.5%), or 7.5% HTS/6% D (7.5% D). Mean arterial pressure (MAP) and tissue oxygen saturation (StO2) were recorded. Laboratory and thrombelastography (TEG) data were collected every 30 minutes. Animals were sacrificed 120 minutes after injury. Analysis of variance was used to compare groups. Significance was defined as p < 0.05.

RESULTS

Baseline characteristics and laboratory values were similar in all groups. All groups achieved a similar degree of shock. Two NS and two 3% animals did not survive to 120 minutes. Fluids containing dextran produced a significantly greater increase in MAP (p < 0.02). Animals receiving 3% D maintained a higher MAP 90 minutes after fluid bolus. Also, 7.5% +/- D produced a significantly greater initial increase in StO2 (p < 0.05). This effect declined after fluid bolus while 3% D continued to improve tissue oxygenation. Significant differences developed between groups in TEG values, hematocrit, fibrinogen, urine sodium, serum sodium, serum chloride, and urine output.

CONCLUSIONS

A single bolus of 3% D after uncontrolled hemorrhagic shock produces an adequate and sustained rise in MAP and StO2 and attenuates hypercoagulability. Resuscitation with 7.5% +/- D produces significantly increased urine output accompanied by a decline in MAP and StO2 over time. A single bolus of 7.5% D results in significant dilutional anemia and relative hypofibrinogenemia.

Prediction of massive blood transfusion in cardiac surgery

PURPOSE

In cardiac surgery with cardiopulmonary bypass (CPB), excessive blood loss requiring the transfusion of multiple red blood cell (RBC) units is a common complication that is associated with significant morbidity and mortality. The objective of this study was to develop a prediction rule for massive blood transfusion (MBT) that could be used to optimize the management of, and research on, at-risk patients.

METHODS

Data were collected prospectively over the period from 2000 to 2005, on patients who underwent surgery with CPB at one hospital. Patients who received > or = five units of RBC within one day of surgery were classified as MBT. Logistic regression was used to appropriately select and weigh perioperative variables in the prediction rule, which was developed on the initial 60% of the sample and validated on the remaining 40%.

RESULTS

Of the 10,667 patients included, 925 (8.7%) had MBT. The clinical prediction rule included 12 variables (listed in order of predictive value: CPB duration, preoperative hemoglobin concentration, body surface area, nadir CPB hematocrit, previous sternotomy, preoperative shock, preoperative platelet count, urgency of surgery, age, surgeon, deep hypothermic circulatory arrest, and type of procedure) and was highly discriminative (c-index = 0.88). In the validation set, those classified as low-, moderate-, and high-risk by a simple risk score derived from the prediction rule had a 5%, 27%, and 58% chance of MBT, respectively.

CONCLUSION

A clinical prediction rule was developed that accurately identified patients at low-risk or high-risk for MBT. Studies are needed to determine the external generalizability and clinical utility of the prediction rule.

EFFECT OF DIFFERENT RESUSCITATION FLUIDS ON CYTOKINE RESPONSE IN A RAT MODEL OF HEMORRHAGIC SHOCK

This study was designed to determine the effects of different resuscitation fluids on the production of proinflammatory and anti-inflammatory cytokines in an animal model of hemorrhagic shock. Wistar male rats (n = 24; 8/group) were subjected to a volume-controlled hemorrhagic shock for 30 minutes and resuscitated as follows: (1) sham group without resuscitation, (2) lactated Ringer solution (LR), 3:1; (3) 4% hydroxyethyl starch (HES) solution, 1:1; and (4) 4% modified fluid gelatin (GEL), 1:1. Hemodynamic parameters were recorded, and blood samples were collected at 0 min and 30, 90, 150, 210, 270, and 330 min after hemorrhage for plasma levels of IL-6, IL-10, and TNFalpha. The circulating concentrations of IL-6 at 90, 150, 210, 270, and 330 min and TNFalpha levels at 150, 210, and 270 min after hemorrhage were significantly elevated in animals resuscitated with GEL compared with HES or LR (P < 0.05). At 210, 270, and 330 min, IL-10 concentration was decreased significantly in GEL-resuscitated rats compared with rats resuscitated with LR or HES (P < 0.05). Mean blood pressure and serum levels of lactate after resuscitation were not different among three kinds of fluids. LR, HES, and GEL are comparable in volume efficacy for resuscitation of hemorrhagic shock but are associated with different postresuscitation immune responses. Resuscitation with GEL may be associated with cytokine production favoring a proinflammatory response. The marked elevation of IL-6 observed in the GEL-treated animals may play a role in the relatively high frequency of anaphylactoid reaction in clinical use of GEL.

Complications of hydroxyethyl starch in acute ischemic stroke and other brain injuries

Serious complications of hydroxyethyl starch (HES) administration have been repeatedly demonstrated in clinical trials of acute ischemic stroke and other brain injuries. Such complications have prompted the premature termination of several randomized trials. Coagulopathy and bleeding have been the most frequently documented complications in the brain injury setting and have occurred after exposure to HES solutions of widely varying molecular weight and substitutions. Severe, protracted, refractory pruritus is another HES complication. Claims of safety for HES solutions have often been made on the basis of small trials with inadequate statistical power. Additionally, the safety has been typically assessed in highly selected low-risk patient populations receiving relatively small HES doses, so that the results cannot be generalized to routine clinical practice. The preponderance of available evidence suggests that HES solutions should be avoided in acute ischemic stroke and other brain injuries.

Pruritus precipitated by hydroxyethyl starch: a review

Hydroxyethyl starch (HES) is widely used for fluid management in broad populations of patients, particularly in the surgery and intensive care settings. Pruritus, often manifested as pruritic crises, is increasingly being recognized as a common major adverse effect of HES administration. This iatrogenic form of pruritus is frequently severe and protracted with a serious negative impact on patient quality of life, including sleep disturbance, disruption of daily routine and mental distress. Such pruritus is generally refractory to available therapies and can persist for up to 12-24 months. All currently clinically available HES solutions entail the risk of pruritus, including those of diverse molecular weights and substitutions. Although dose dependent, HES-induced pruritus nevertheless can often be provoked by relatively low routine doses. The pathophysiological basis for pruritus is the widespread tissue deposition of HES, prominently in macrophages. HES tissue deposits are long lasting and sometimes massive. Usually several weeks elapse between HES exposure and the onset of pruritus. Consequently, it is important to inquire about prior HES exposure in the diagnostic evaluation of pruritus sine materia. Awareness about the scope of the pruritus problem needs to increase among physicians administering HES. Well-designed clinical outcome studies are needed to assess more fully the incidence, dose dependency and mechanisms of pruritus with particular HES solutions.

Assessment and treatment of perfusion abnormalities in the emergency patient

Many patients presented to the emergency veterinarian are suffering from global or local tissue hypoperfusion. Global or systemic hypoperfusion can occur secondary to a reduction in the effective circulating intravascular volume (hypovolemic shock) or reduced ability of the heart to pump blood around the body secondary to reduced cardiac function (cardiogenic shock),obstruction to blood flow (obstructive shock), or maldistribution of the circulating intravascular volume (distributive shock). Initial assessment involving physical examination supplemented by measurement of hemodynamic and metabolic parameters allows the clinician to recognize and treat patients with severe global hypoperfusion. Use of techniques like sublingual capnometry and measurement of central venous oxygen saturation may aid recognition and evaluation of early hypoperfusion. Treatment decisions are made based on an assessment of the severity of the hypoperfusion and its probable underlying cause. Early effective treatment of hypoperfusion is likely to lead to a better outcome for the patient.