Hydroxyethyl starch: an alternative to plasma for postoperative volume expansion after cardiac surgery

Ca2+-Responsive Glyco-insulin

Chemical modification of peptides and proteins, such as PEGylation and lipidation, creates conjugates with new properties. However, they are typically not dynamic or stimuli-responsive. Self-assembly controlled by a stimulus will allow adjusting properties directly. Here, we report that conjugates of oligogalacturonic acids (OGAs), isolated from plant-derived pectin, are Ca²⁺-responsive. We report the conjugation of OGA to human insulin (HI) to create new glyco-insulins. In addition, we coupled OGA to model peptides. We studied their self-assembly by dynamic light scattering, small-angle X-ray scattering, and circular dichroism, which showed that the self-assembly to form nanostructures depended on the length of the OGA sequence and Zn²⁺ and Ca²⁺ concentrations. Subcutaneous administration of OGA12-HI with Zn²⁺ showed a stable decrease in blood glucose over a longer period of time compared to HI, despite the lower receptor binding affinity.

Hydroxyethyl starch based smart nanomedicine

In the past decades, the vigorous development of nanomedicine has opened up a new world for drug delivery. Hydroxyethyl starch (HES), a clinical plasma volume expander which has been widely used for years, is playing an attracting role as drug carriers. Compared with all other polysaccharides, HES has proven its unique characteristics for drug delivery platforms, including good manufacture practice, biodegradability, biocompatibility, abundant groups for chemical modification, excellent water solubility, and tailorability. In this review, an overview of various types of HES based drug delivery systems is provided, including HES-drug conjugates, HES-based nano-assemblies, HES-based nanocapsules, and HES-based hydrogels. In addition, the current challenges and future opportunities for design and application of HES based drug delivery systems are also discussed. The available studies show that HES based drug delivery systems has significant potential for clinical translation.

Safety and efficacy of peri-operative administration of hydroxyethyl starch in children undergoing surgery: A systematic review and meta-analysis

BACKGROUND

Hydroxyethyl starch (HES) solutions have shown their efficiency for intravascular volume expansion. A safety recommendation limiting their use in adult patients has recently been made.

OBJECTIVE

To assess the efficacy and adverse effects of HES when administered intra-operatively to paediatric patients.

DESIGN

Systematic review with meta-analyses. Data were analysed using classical mean differences [and their 95% confidence intervals (CIs)] and trial sequential analysis. A Grading of Recommendations Assessment, Development and Evaluation (GRADE) classification was performed for all outcomes. Reviewers extracted valid data, including perioperative total fluid intakes, mortality, renal function, coagulation tests, blood loss and length of hospital and ICU stay.

DATA SOURCES

Searches were performed in databases (Pubmed, Embase, Cochrane central register of controlled trials), clinical trials register, and open access journals not indexed in major databases.

ELIGIBILITY CRITERIA

Randomised controlled trials (RCTs) published before December 2016 involving paediatric patients who received 6% low molecular weight HES.

RESULTS

Nine RCTs involving 530 peri-operative paediatric patients were analysed. Compared with other fluids, HES did not significantly modify the amount of peri-operative fluid administered [mean difference 0.04; 95% CI (-1.76 to 1.84) ml kg], urine output [mean difference -33; 95% CI (-104 to 38) ml kg] or blood loss [mean difference -0.09; (-0.32 to 0.15) ml kg]. Trial sequential analysis determined that the outcomes for peri-operative fluid and urine output were underpowered. All results were graded as very low quality of evidence.

CONCLUSION

Intravascular volume expansion with low molecular weight 6% HES did not appear to modify renal function, blood loss or transfusion when administered to children during the peri-operative period. However, given the lack of statistical power and the very low GRADE quality of evidence, more high-quality RCTs are needed to explore these outcomes.

THE USE OF HYDROXYETHYL STARCH 200/0,5 AS PLASMA SUBTITUTES IS SAFE IN HYPOVOLEMIC PATIENTS AS INDICATED IN CHANGES OF N-ACETYL--GLUCOSAMINIDASE AND CREATININ SERUM PARAMETERS

Hydroxyethyl Starch (HES) is a compound that improves intravascular volume effectively and rapidly without causing tissue edema. However, HES also has renal safety profile which is still being debated. Based on clinical experience in Dr. Soetomo Hospital, the frequency of acute renal failure following HES 200/0.5 administration at a dose of less than 20 ml/kg (maximum dose) is very rare. The purpose of this study was to evaluate the effect of HES 200/0.5 at a dose of less than 20 ml/kg in patients undergoing surgery. N-acetyl-b-D-Glucosaminidase (NAG) per urine creatinine ratio and creatinine serum were used as main parameter to assess renal injury. This research was observational and prospective design in patients undergoing elective surgery at Gedung Bedah Pusat Terpadu, Dr. Soetomo Hospital, who requiring resuscitation therapy with HES 200/0.5 and met the inclusion and exclusion criteria. NAG was measured prior to surgery and 12 hours after administration of fluid therapy, while creatinine serum was observed before surgery and 48 hours after resuscitation. This study was conducted for three months, and obtained 50 subjects divided into 2 groups, crystalloid group and HES 200/0.5 group. Demographic and baseline characteristics did not differ between groups, except the total bleeding volume. Total bleeding in HES 200/0.5group was higher than crystalloid group (p <0.0001). The mean volume of fluid received in HES 200/0.5 group was 2042.0 ± 673.9 mL, higher when compared with that of crystalloid group (910.0 ± 592.0 ml). Doses of HES 200/0.5 received was 8.31 ± 4.86 ml/kg. Measurement of the of NAG/creatinine ratio and creatinine serum showed significant increase in both groups, but still within the normal range. In addition, the value of these two parameters did not differ between groups. In conclusion, HES 200/0.5 in a dose of less than 20 ml/kg is safe to use in patients who suffered from hypovolemic hemorrhage, without prior history of renal impairment.

Coagulation complications following trauma

Traumatic injury is one of the leading causes of death, with uncontrolled hemorrhage from coagulation dysfunction as one of the main potentially preventable causes of the mortality. Hypothermia, acidosis, and resuscitative hemodilution have been considered as the significant contributors to coagulation manifestations following trauma, known as the lethal triad. Over the past decade, clinical observations showed that coagulopathy may be present as early as hospital admission in some severely injured trauma patients. The hemostatic dysfunction is associated with higher blood transfusion requirements, longer hospital stay, and higher mortality. The recognition of this early coagulopathy has initiated tremendous interest and effort in the trauma community to expand our understanding of the underlying pathophysiology and improve clinical treatments. This review discusses the current knowledge of coagulation complications following trauma.

Incidence of postoperative death and acute kidney injury associated with i.v. 6% hydroxyethyl starch use: systematic review and meta-analysis

BACKGROUND

Trials suggest that the use of i.v. hydroxyethyl starch (HES) solutions is associ-ated with increased risk of death and acute kidney injury (AKI) in critically ill patients. It is uncertain whether similar adverse effects occur in surgical patients.

METHODS

Systematic review and meta-analysis of trials in which patients were randomly allocated to 6% HES solutions or alternative i.v. fluids in patients undergoing surgery. Ovid Medline, Embase, Cinhal, and Cochrane Database of Systematic Reviews were searched for trials comparing 6% HES with clinically relevant non-starch comparator. The primary end-point was hospital mortality. Secondary endpoints were requirement for renal replacement therapy (RRT) and author-defined AKI. Pre-defined subgroups were cardiac and non-cardiac surgery.

RESULTS

Four hundred and fifty-six papers were identified; of which 19 met the inclusion criteria. In total, 1567 patients were included in the analysis. Dichotomous outcomes were expressed as a difference of proportions [risk difference (RD)]. There was no difference in hospital mortality [RD 0.00, 95% confidence interval (CI) -0.02, 0.02], requirement for RRT (RD -0.01, 95% CI -0.04, 0.02), or AKI (RD 0.02, 95% CI -0.02 to 0.06) between compared arms overall or in predefined subgroups.

CONCLUSIONS

We did not identify any differences in the incidence of death or AKI in surgical patients receiving 6% HES. Included studies were small with low event rates and low risk of heterogeneity. Narrow CIs suggest that these findings are valid. Given the absence of demonstrable benefit, we are unable to recommend the use of 6% HES solution in surgical patients.

Comparisons of lactated Ringer's and Hextend resuscitation on hemodynamics and coagulation following femur injury and severe hemorrhage in pigs

BACKGROUND

This study compared coagulation function after resuscitation with Hextend and lactated Ringer's (LR) solution in pigs with tissue injury and hemorrhagic shock.

METHODS

Pigs were randomized into control (n = 7 each), LR, and Hextend groups. Femur fracture was induced using the captive bolt stunner at midshaft of the pigs' left legs, followed by hemorrhage of 60% total blood volume and resuscitation with either Hextend (equal to bled volume) or LR to reach the same mean arterial pressure. Pigs in the control group were not bled or resuscitated. Hemodynamics was monitored hourly for 6 hours. Blood samples were taken at baseline (BL), after hemorrhage, 15 minutes, 3 hours, and 6 hours after resuscitation for blood and coagulation measurements.

RESULTS

Mean arterial pressure decreased to 50% of BL by the 60% hemorrhage but returned to near BL within 1 hour after LR or Hextend resuscitation. Heart rate was increased (from 91 ± 4 beats per minute to 214 ± 20 beats per minute) by hemorrhage and decreased after resuscitation but remained elevated above BL in both groups. Resuscitation with Hextend (42 mL/kg) or LR (118 ± 3 mL/kg) reduced hematocrit, total protein, fibrinogen, and platelet counts, with greater decreases shown in the Hextend group. Clot strength was lower but returned to BL by 3 hours in the LR group, whereas it remained reduced for the 6-hour period after Hextend. The overall clotting capacity after LR was decreased after hemorrhage and resuscitation but returned to BL by 3 hours, whereas it remained low after Hextend for the 6-hour experiment period.

CONCLUSION

After traumatic hemorrhage, coagulation function was restored within 6 hours with LR resuscitation but not with Hextend. The lack of recovery after Hextend is likely caused by greater hemodilution and possible effects of starches on coagulation substrates and further documents the need to restrict the use of high-molecular-weight starch in resuscitation fluids for bleeding casualties.

Colloid solutions for fluid resuscitation

BACKGROUND

Colloids are widely used in the replacement of fluid volume. However, doubts remain as to which colloid is best. Different colloids vary in their molecular weight and therefore in the length of time they remain in the circulatory system. Because of this, and their other characteristics, they may differ in their safety and efficacy.

OBJECTIVES

To compare the effects of different colloid solutions in patients thought to need volume replacement.

SEARCH METHODS

We searched the Cochrane Injuries Specialised Register (searched 1 December 2011), the Cochrane Central Register of Controlled Trials 2011, issue 4 (The Cochrane Library); MEDLINE (Ovid) (1948 to November Week 3 2011); EMBASE (Ovid) (1974 to 2011 Week 47); ISI Web of Science: Science Citation Index Expanded (1970 to 1 December 2011); ISI Web of Science: Conference Proceedings Citation Index-Science (1990 to 1 December 2011); CINAHL (EBSCO) (1982 to 1 December 2011); National Research Register (2007, Issue 1) and PubMed (searched 1 December 2011). Bibliographies of trials retrieved were searched, and for the initial version of the review drug companies manufacturing colloids were contacted for information (1999).

SELECTION CRITERIA

Randomised controlled trials comparing colloid solutions in critically ill and surgical patients thought to need volume replacement.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data and assessed the quality of the trials. The outcomes sought were death, amount of whole blood transfused, and incidence of adverse reactions.

MAIN RESULTS

Eighty-six trials, with a total of 5,484 participants, met the inclusion criteria. Quality of allocation concealment was judged to be adequate in 33 trials and poor or uncertain in the rest.Deaths were reported in 57 trials. For albumin or plasma protein fraction (PPF) versus hydroxyethyl starch (HES) 31 trials (n = 1719) reported mortality. The pooled relative risk (RR) was 1.06 (95% confidence interval (CI) 0.86 to 1.31). When the trials by Boldt were removed from the analysis the pooled RR was 0.90 (95% CI 0.68 to 1.20). For albumin or PPF versus gelatin, nine trials (n = 824) reported mortality. The RR was 0.89 (95% CI 0.65 to 1.21). Removing the study by Boldt from the analysis did not change the RR or CIs. For albumin or PPF versus dextran four trials (n = 360) reported mortality. The RR was 3.75 (95% CI 0.42 to 33.09). For gelatin versus HES 22 trials (n = 1612) reported mortality and the RR was 1.02 (95% CI 0.84 to 1.26). When the trials by Boldt were removed from the analysis the pooled RR was 1.03 (95% CI 0.84 to 1.27). RR was not estimable in the gelatin versus dextran and HES versus dextran groups.Forty-one trials recorded the amount of blood transfused; however, quantitative analysis was not possible due to skewness and variable reporting. Twenty-four trials recorded adverse reactions, with two studies reporting possible adverse reactions to gel and one to HES.

AUTHORS' CONCLUSIONS

From this review, there is no evidence that one colloid solution is more effective or safe than any other, although the CIs were wide and do not exclude clinically significant differences between colloids. Larger trials of fluid therapy are needed if clinically significant differences in mortality are to be detected or excluded.

Colloid solutions for fluid resuscitation

BACKGROUND

Colloids are widely used in the replacement of fluid volume. However doubts remain as to which colloid is best. Different colloids vary in their molecular weight and therefore in the length of time they remain in the circulatory system. Because of this and their other characteristics, they may differ in their safety and efficacy.

OBJECTIVES

To compare the effects of different colloid solutions in patients thought to need volume replacement.

SEARCH METHODS

We searched the Cochrane Injuries Specialised Register (searched 1 Dec 2011), Cochrane Central Register of Controlled Trials 2011, issue 4 (The Cochrane Library); MEDLINE (Ovid) (1948 to November Week 3 2011); EMBASE (Ovid) (1974 to 2011 Week 47); ISI Web of Science: Science Citation Index Expanded (1970 to 1 Dec 2011); ISI Web of Science: Conference Proceedings Citation Index-Science (1990 to 1 Dec 2011); CINAHL (EBSCO) (1982 to 1 Dec 2011); National Research Register (2007, Issue 1) and PubMed (searched 1 Dec 2011). Bibliographies of trials retrieved were searched, and for the initial version of the review drug companies manufacturing colloids were contacted for information (1999).

SELECTION CRITERIA

Randomised controlled trials comparing colloid solutions in critically ill and surgical patients thought to need volume replacement.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the quality of the trials. The outcomes sought were death, amount of whole blood transfused, and incidence of adverse reactions.

MAIN RESULTS

Ninety trials, with a total of 5678 participants, met the inclusion criteria. Quality of allocation concealment was judged to be adequate in 35 trials and poor or uncertain in the rest.Deaths were obtained in 61 trials. For albumin or PPF versus hydroxyethyl starch (HES) 32 trials (n = 1769) reported mortality. The pooled relative risk (RR) was 1.07 (95% CI 0.87 to 1.32). When the trials by Boldt were removed from the analysis the pooled RR was 0.90 (95% CI 0.68 to 1.20). For albumin or PPF versus gelatin, nine trials (n = 824) reported mortality. The RR was 0.89 (95% CI 0.65 to 1.21). Removing the study by Boldt from the analysis did not change the RR or confidence intervals. For albumin or PPF versus Dextran four trials (n = 360) reported mortality. The RR was 3.75 (95% CI 0.42 to 33.09). For gelatin versus HES 25 trials (n = 1756) reported mortality and the RR was 1.03 (95% CI 0.84 to 1.26). When the trials by Boldt were removed from the analysis the pooled RR was 1.04 (95% CI 0.85 to 1.27). RR was not estimable in the gelatin versus dextran and HES versus dextran groups.Forty five trials recorded the amount of blood transfused, however quantitative analysis was not possible due to skewness and variable reporting. Twenty-four trials recorded adverse reactions, with two studies reporting possible adverse reactions to Gel and one to HES.

AUTHORS' CONCLUSIONS

From this review, there is no evidence that one colloid solution is more effective or safe than any other, although the confidence intervals are wide and do not exclude clinically significant differences between colloids. Larger trials of fluid therapy are needed if clinically significant differences in mortality are to be detected or excluded.

Colloid solutions for fluid resuscitation

BACKGROUND

Colloids are widely used in the replacement of fluid volume. However doubts remain as to which colloid is best. Different colloids vary in their molecular weight and therefore in the length of time they remain in the circulatory system. Because of this and their other characteristics, they may differ in their safety and efficacy.

OBJECTIVES

To compare the effects of different colloid solutions in patients thought to need volume replacement.

SEARCH STRATEGY

We searched the Cochrane Injuries Group's specialised register, CENTRAL (2007, Issue 1), MEDLINE (1994 to March 2007), EMBASE (1974 to March 2007), and the National Research Register (2007, Issue 1). Bibliographies of trials retrieved were searched, and drug companies manufacturing colloids were contacted for information. The search was last updated in March 2007.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing colloid solutions in critically ill and surgical patients thought to need volume replacement. The outcomes measured were death, amount of whole blood transfused, and incidence of adverse reactions.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the quality of the trials.

MAIN RESULTS

Seventy trials, with a total of 4375 participants, met the inclusion criteria. Quality of allocation concealment was judged to be adequate in 24 trials and poor or uncertain in the rest.Deaths were obtained in 46 trials. For albumin or PPF versus hydroxyethyl starch (HES) 25 trials (n = 1234) reported mortality. The pooled relative risk (RR) was 1.14 (95% CI 0.91 to 1.43). When the trials by Boldt are removed from the analysis the pooled RR was 0.97 (95% CI 0.70 to 1.35). For albumin or PPF versus gelatin, seven trials (n = 636) reported mortality. The RR was 0.97 (95% CI 0.68 to 1.39). For albumin or PPF versus Dextran four trials (n = 360) reported mortality. The RR was 3.75 (95% CI 0.42 to 33.09). For gelatin versus HES 18 trials (n = 1337) reported mortality and RR was 1.00 (95% CI 0.80 to 1.25). RR was not estimable in the gelatin versus dextran and HES versus dextran groups.Thirty-seven trials recorded the amount of blood transfused, however quantitative analysis was not possible due to skewness and variable reporting. Nineteen trials recorded adverse reactions, but none occurred.

AUTHORS' CONCLUSIONS

From this review, there is no evidence that one colloid solution is more effective or safe than any other, although the confidence intervals are wide and do not exclude clinically significant differences between colloids. Larger trials of fluid therapy are needed if clinically significant differences in mortality are to be detected or excluded.

Hydroxyethyl starch induced acquired von Willebrand's disease

Hydroxyethyl starch (HES) (Hespan, DuPont) is a widely used synthetic volume expander which in standard doses of up to 1.5l in 24 h has no significant effect on coagulation (Munsch et al. 1988). However, the data sheet states that in large volumes HES may alter the coagulation mechanism. We now report a case of HES induced acquired von Willebrand's disease (vWD) in which severe bleeding occurred.

Colloid solutions for fluid resuscitation

BACKGROUND

Colloids are widely used in the replacement of fluid volume. However doubts remain as to which colloid is best. Different colloids vary in their molecular weight and therefore in the length of time they remain in the circulatory system. Because of this and their other characteristics, they may differ in their safety and efficacy.

OBJECTIVES

To compare the effects of different colloid solutions in patients thought to need volume replacement.

SEARCH STRATEGY

We searched the Cochrane Injuries Group specialised register, CENTRAL (2007, Issue 1), MEDLINE (1994 to March 2007), EMBASE (1974 to March 2007), and the National Research Register (2007, issue 1). Bibliographies of trials retrieved were searched, and drug companies manufacturing colloids were contacted for information. The search was last updated in March 2007.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing colloid solutions in critically ill and surgical patients thought to need volume replacement. The outcomes measured were death, amount of whole blood transfused, and incidence of adverse reactions.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the quality of the trials.

MAIN RESULTS

Seventy trials, with a total of 4375 participants, met the inclusion criteria. Quality of allocation concealment was judged to be adequate in 24 trials and poor or uncertain in the rest. Deaths were obtained in 46 trials. For albumin or PPF versus hydroxyethyl starch (HES) 25 trials (n = 1234) reported mortality. The pooled relative risk (RR) was 1.14 (95% CI 0.91 to 1.43). For albumin or PPF versus gelatin, seven trials (n = 636) reported mortality. The RR was 0.97 (95% CI 0.68 to 1.39). For albumin or PPF versus Dextran four trials (n = 360) reported mortality. The RR was 3.75 (95% CI 0.42 to 33.09). For gelatin versus HES 18 trials (n = 1337) reported mortality and RR was 1.00 (95% CI 0.80 to 1.25). RR was not estimable in the gelatin versus dextran and HES versus dextran groups.Thirty-seven trials recorded the amount of blood transfused, however quantitative analysis was not possible due to skewness and variable reporting. Nineteen trials recorded adverse reactions, but none occurred.

AUTHORS' CONCLUSIONS

From this review, there is no evidence that one colloid solution is more effective or safe than any other, although the confidence intervals are wide and do not exclude clinically significant differences between colloids. Larger trials of fluid therapy are needed if clinically significant differences in mortality are to be detected or excluded.

Colloid solutions for fluid resuscitation

BACKGROUND

Colloids are widely used in the replacement of fluid volume. However doubts remain as to which colloid is best. Different colloids vary in their molecular weight and therefore in the length of time they remain in the circulatory system. Because of this and their other characteristics, they may differ in their safety and efficacy.

OBJECTIVES

To compare the effects of different colloid solutions in patients thought to need volume replacement.

SEARCH STRATEGY

We searched the Cochrane Injuries Group specialised register, the Cochrane Controlled Trials Register (2002 Issue 3), MEDLINE (1994-2002/07), EMBASE (1974-2002 August week 1), and the National Research Register (2002 issue 3). Bibliographies of trials retrieved were searched, and drug companies manufacturing colloids were contacted for information. The search was last updated in September 2002.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing colloid solutions in critically ill and surgical patients thought to need volume replacement. The main outcomes measured were death, amount of whole blood transfused, and incidence of adverse reactions.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the quality of the trials.

MAIN RESULTS

Fifty-seven trials met the inclusion criteria, with a total of 3659 participants. Quality of allocation concealment was judged to be adequate in 20 trials and poor or uncertain in 37. Deaths were obtained from 36 trials. For albumin or PPF versus hydroxyethyl starch (HES) 20 trials (n=1029) reported mortality. The pooled relative risk (RR) was 1.17 (95% CI 0.91, 1.50). For albumin or PPF versus gelatin four trials (n=542) reported mortality. The RR was 0.99 (0.69, 1.42). For gelatin vs HES 11 trials (n=945) reported mortality, RR was 1.00 (0.78,1.28). RR was not estimable in the albumin vs dextran, gelatin vs dextran, and HES vs dextran groups. Thirty-six trials recorded the amount of blood transfused, however quantitative analysis was not possible due to skewness and variable reporting. Fifteen trials recorded adverse reactions, but none occurred.

REVIEWER'S CONCLUSIONS

From this review, there is no evidence that one colloid solution is more effective or safe than any other, although the confidence intervals are wide and do not exclude clinically significant differences between colloids. Larger trials of fluid therapy are needed if clinically significant differences in mortality are to be detected or excluded.

Prehospital care of the patient with major trauma

Recent research efforts have demonstrated that many longstanding practices for the prehospital resuscitation of trauma patients may be inappropriate under certain circumstances. For example, traditional practices, such as application of anti-shock garments and i.v. fluid administration to raise blood pressure, may even be detrimental in certain patients with uncontrolled bleeding, particularly those with penetrating injuries. ETI, although potentially capable of transiently prolonging a patient's ability to tolerate circulatory arrest, may also be harmful if overzealous PPV further compromises cardiac output, particularly in those patients with severe hemodynamic instability. In addition, if these procedures delay patient transport, any benefit that they may offer could be outweighed by the delay in definitive care. Although traditionally taught to "hyperventilate" the patient with severe head injury, current recommendations are to avoid this tactic unless there is evidence of herniation. Even time-honored traditions, such as universal spinal precautions and CPR during circulatory arrest, are being scrutinized [2,134]. Further prospective randomized clinical trials are needed to better define the role of many overlapping therapies in prehospital trauma care. Such research must specifically address and stratify the different mechanisms of injury, anatomic areas involved, and the physiologic staging of the injury. Furthermore, the efficacy of a single intervention may be masked by a confounding variable [5]. For example, a trial of an effective new HBOC in moribund patients that indicates no advantage in the study results may have been confounded by overzealous PPV, which may have led to suboptimal outcomes. It is hoped that, in the future, EMS physicians will be able to not only better discriminate in their management of patients with major trauma but also improve outcomes as a result.

[Effects of plasma substitutes on hemostasis]

OBJECTIVE

Data synthesis on haemostasis effects of cristalloids and colloids and clinical implications for their use for plasma volume replacement.

DATA SOURCES

Data were searched in the Medline database from 1954 to 2000 using the following key-words: cristalloids, colloids, albumin, gelatin, dextran, hydroxyethyl starch, haemostasis, von Willebrand disease, haemodilution.

DATA EXTRACTION

Publications from 1954 to 1990 were selected depending on the quality of their methodology. Most of articles published after 1990 and all types including case report were accepted.

DATA SYNTHESIS

Cristalloids induces a moderate hypercoagulable state with 10 to 30% haemodilution. Hypocoagulation is observed above 50% haemodilution. Albumin does not impair hemostasis except with a 50% or more haemodilution where hypocoagulation is observed. Dextran dramatically impairs haemostasis and fibrinolysis. With increasing dose, a progressive decrease of all von Willebrand multimers, mostly the largest, is observed. Till 50% haemodilution, gelatin has a moderate impact on hemostasis, but platelet aggregation is moderately modified. However this moderate impairment of haemostasis may potentiate the haemostatic effect of other colloids when used in association with gelatin. More than 30% haemodilution with hydroxyethyl starch (HES) has a serious effect in vitro on platelet function and fibrinoformation. In most studies in human, less than 20 ml.kg-1 plasma volume replacement has no clinical impact, but in some evaluations postoperative bleeding is more important with HES, particularly HES 450, in comparison to other colloids. With HES 450 and HES 200 highly substituted (0.6 of degree of substitution) intravascular cumulation of large molecules leads to type I von Willebrand syndrome when doses overtake 80 ml.kg-1. Dextran and HES are prohibited in patients with impaired haemostasis due to congenital disease (haemophilia and von Willebrand disease) or acquired defect (thrombocytopenia). Caution is required in patients with renal failure or receiving antithrombotic or non-steroidal anti-inflammatory agents. Patients without a haemorrhagic diathesis must not received more than 1.5 g.kg-1.j-1 of dextran and restrictive conditions of use must be respected with HES.

CONCLUSION

Except isotonic cristalloids, all colloids induce haemostastic changes particularly for haemodilution over 30%. Effects are more pronounced with HES and dextran.

Effects on coagulation of intravenous crystalloid or colloid in patients undergoing peripheral vascular surgery

BACKGROUND

This study investigated whether haemodilution-enhanced coagulation can be demonstrated under regional anaesthesia, whether this occurs before surgery, and whether the fluid used influences the effect.

METHODS

Patients were randomly allocated to receive either crystalloid or colloid intravenous fluid. An epidural was administered. Samples of venous blood were taken before fluid administration, after completion of the epidural and initial fluid load, during surgery before heparin, and after 24 h. Thrombelastograph analysis was performed, and full blood count, international normalised ratio, activated partial thromboplastin time, D-dimers and thrombin-antithrombin complex were measured.

RESULTS

In the crystalloid group, enhanced coagulation compared with baseline was demonstrated after initial fluid load (mean (SD) r-time 10.1 (4.9) min; P < 0.033; k-time 3.5 (1.7) min; P < 0.01; alpha-angle 54.9 (13.9) degrees; P < 0.01) and before heparin administration (r-time 8.8 (3.9) min; P < 0.01; alpha-angle 54.9 (12.6) degrees; P < 0.02). There was no enhancement of coagulation in the colloid group. There were no changes from baseline after 24 h.

CONCLUSIONS

This study confirms that the enhanced perioperative coagulation mechanism is related to dilution, rather than surgery, and is triggered by rapid crystalloid haemodilution. Consideration should be given to the use of colloid rather than crystalloid solutions for rapid fluid loading in vasculopathic patients undergoing surgery.

Fluid resuscitation of the patient with major trauma

Current reviews and consensus documents now recommend a more discriminating approach to the traditional practices of delivering liberal infusions of intravenous fluid to all major trauma patients with suspected or known major hemorrhage. The evolving evidence suggests that aggressive fluid resuscitation prior to hemostasis leads to additional bleeding through hydraulic acceleration of hemorrhage, soft clot dissolution, and dilution of clotting factors. Aggressive preoperative fluid infusion is still considered appropriate for unconscious patients without palpable blood pressure or for those with controllable hemorrhage (e.g. isolated extremity or head injury), However, the latest recommendations are to limit or delay intravenous fluid resuscitation preoperatively in those with uncontrollable hemorrhage (e.g. those with penetrating torso injuries), even if they are hypo-perfusing. Although most clinicians still generally support fluid resuscitation for multisystem blunt trauma, particularly with head injury, the most recent experimental data have begun to challenge this traditional practice as well, suggesting a 'slow infusion' approach when there is risk for uncontrolled internal bleeding. By providing oxygen delivery with slow, limited infusion, new hemoglobin-based oxygen carriers might help to resolve the current dilemma of having to limit preoperative resuscitation when there is risk of uncontrolled hemorrhage.

Hydroxyethyl starch in balanced electrolyte solution (Hextend)--pharmacokinetic and pharmacodynamic profiles in healthy volunteers

Hextend is a new plasma volume expander containing 6% hydroxyethyl starch (HES) in a physiologically balanced medium of electrolytes, glucose, and lactate (weight average, molecular weight 670 kDa, molar substitution 0.75). This open-label study was designed to investigate the pharmacokinetic and pharmacodynamic profiles of Hextend in 21 healthy volunteers. We infused Hextend 10 ml/kg IV over 20 min and determined serum concentrations of HES at selected intervals over a 7-day period. Serum concentration-time curves indicated mixed pharmacokinetic behavior reflecting a two-compartment model in most subjects. The median serum half-life over 7 days was 38.2 h. The balanced formulation of the suspension medium did not seem to affect distribution, metabolism, or excretion of Hextend when compared with similar HES. Pharmacodynamic analysis demonstrated decreases in some plasma components compatible with the infusion of that volume of fluid and the duration of plasma volume expansion. Other plasma components remained unchanged, reflecting the benefit of a balanced electrolyte solution. Hemodilution was observed for 24--48 h after short-term infusion of Hextend. Some hemostatic indices showed moderate changes, and serum amylase demonstrated a temporary increase. Our study suggested that Hextend has pharmacokinetic and pharmacodynamic profiles that are similar to those of other HES.

IMPLICATIONS

Hextend is a new plasma volume expander containing 6% hydroxyethyl starch in a physiologically balanced medium. This open-label volunteer study demonstrated that it has pharmacokinetic and pharmacodynamic profiles similar to those of established HES.

A randomized, blinded trial comparing the hemostatic effects of pentastarch versus hetastarch

BACKGROUND

HES solutions provide a sterile, alternative colloidal fluid to albumin solutions and/or plasma in the management of patients who need plasma volume expansion. Solutions of HES are widely accepted internationally but are used only modestly in the United States, largely because of concerns over hemostasis.

STUDY DESIGN AND METHODS

A randomized, blinded, two-arm trial comparing the hemostatic effects of pentastarch versus hetastarch when infused in the clinically relevant dose of 90 g of HES dissolved in 1.5 L of saline was conducted. Multiple studies of fibrin clot formation, fibrinogen/fibrinolysis, and platelet (PLT) functions were performed before and on multiple occasions for 70 days following HES infusion.

RESULTS

Several significant abnormalities of hemostasis assay results occurred following HES infusions, with hetastarch causing significantly greater abnormalities than pentastarch. Individual clotting proteins and blood PLTs fell modestly because of plasma volume expansion and hemodilution. A fall in excess of that caused by hemodilution was demonstrated for von Willebrand factor antigen plus its associated FVIII and ristocetin cofactor activities. The partial thromboplastin time was prolonged, whereas the thrombin time was shortened. Plt function abnormalities were seen in most subjects to a modest degree. Studies of fibrinolysis were normal.

CONCLUSIONS

Solutions of hetastarch produce significant abnormalities of some hemostasis laboratory results when infused at clinically relevant doses, but it is unlikely that the modest hemostatic abnormalities produced at these doses per se would lead to clinical bleeding. Hetastarch causes greater hemostatic abnormalities than pentastarch, and because both HES solutions have comparable plasma volume-expanding effects, it is reasonable to prefer pentastarch as a plasma volume expander.

Prehospital fluid resuscitation of the patient with major trauma

The most appropriate prehospital approach to resuscitative fluid interventions for trauma patients involves: determining the mechanism of injury (i.e., blunt versus penetrating versus thermal injury); identifying anatomic involvement (i.e., truncal versus isolated head injury versus isolated extremity injury); and staging the condition (i.e., hemodynamic stability versus instability versus moribund state). Based on available data, the liberal use of fluid infusions for presumed uncontrolled internal hemorrhage, such as that usually occurring after penetrating abdominal and thoracic injuries, is no longer advised. Although some infusion might be appropriate in patients with extremely severe hemorrhage (i.e., no palpable blood pressure, unconscious), the priority in such patients is rapid evacuation to definitive surgical intervention, with airway control and intravenous access provided en route. The data are less clear for patients with blunt injuries, particularly those with closed head injury. Most researchers would still recommend that patients with isolated extremity and head injuries, either blunt or penetrating, are candidates for immediate support of blood pressure through fluid infusions. However, the addition of potential intra-abdominal, intrapelvic, or intrathoracic injuries with uncontrolled hemorrhage confounds the decision-making process. Although conventional wisdom has been to provide aggressive blood pressure support under these circumstances through judicious use of isotonic, or perhaps hypertonic, fluid resuscitation, recent experimental data challenge even this philosophy. Use of new blood substitutes might help to resolve some of these issues by providing oxygen delivery with limited volume in the face of uncontrolled hemorrhage.

Albumin versus hydroxyethyl starch in cardiopulmonary bypass surgery: a meta-analysis of postoperative bleeding

BACKGROUND

This meta-analysis tested the hypothesis that cumulative blood loss during the first 24 hours after cardiopulmonary bypass is lower in patients exposed to albumin than hydroxyethyl starch (HES).

METHODS

Randomized controlled trials comparing albumin and HES in cardiopulmonary bypass patients were identified by bibliographic database searches and other methods.

RESULTS

Sixteen trials involving 653 randomized patients were included. In 88% of randomized comparisons, postoperative bleeding was lower in the albumin group, and the standardized mean difference in bleeding favoring albumin across all trials (-0.24; 95% confidence interval, -0.40 to -0.08) was statistically significant. Bleeding differences between albumin and either high or medium molecular weight HES were similar. In trials of adults, the pooled mean blood loss in the albumin group was 693+/-350 mL compared with 789+/-487 mL in the HES group. The estimated proportion of adult albumin group patients with blood loss of more than 1,000 mL was 19% compared with 33% of adult HES group patients. Conclusions. Postoperative blood loss is significantly lower in cardiopulmonary bypass patients exposed to albumin than HES.

Influence of different colloids on molecular markers of haemostasis and platelet function in patients undergoing major abdominal surgery

Synthetic colloids have been reported to cause haemorrhagic complications. The effects of perioperative volume replacement with 4% gelatin (n = 20), 6% low-molecular weight (LMW) hydroxyethyl starch (HES) (Mw: 70,000 dalton; HES 70/0.5; n = 20) and 6% medium-molecular weight (MMW) HES (Mw: 200,000 dalton; HES 200/0.5; n = 20) on haemostasis were assessed in patients undergoing major abdominal surgery. Volume was administered to keep central venous pressure (CVP) between 10 and 14 mm Hg. Conventional global coagulation tests, molecular markers of coagulation, and platelet function (using a platelet function analyser (PFA-100) with ADP as inductor) were monitored prior to surgery (T0), at the end of surgery (T1), 4 h after the end of surgery (T2), and on the morning of the first postoperative day (T3). Significantly more gelatin (2900 (SD 320) ml) than HES 200 (2150 (312) ml) was given during the study period. Bleeding and the use of allogeneic blood-blood products were similar in all groups. Markers of thrombin generation (F1 + 2), of thrombin neutralization (TAT III complex), and of fibrin formation and its degradation (D-dimer) increased significantly during and after surgery without showing significant group differences. Factor VIII and von Willebrand factor (vWF) also increased in all groups beyond the normal range, showing the significantly highest increase in the gelatin-treated group (VIII: from 173 (36) to 266 (33) U dl-1; vWF: from 164(33) to 238 (31) U dl-1). Platelet function remained within the normal range and without group differences throughout the study period. We can conclude that all three solutions can be used safely in patients undergoing major abdominal surgery with regard to the haemostatic process.

Microparticle-containing oncotic solutions augment in-vitro clot disruption by ultrasound

Echocardiographic contrast agents enhance blood clot disruption by ultrasound. It has been suggested that the microbubbles add nuclei for the enhancement of cavitation by ultrasound. However, microbubbles are rapidly destroyed by the ultrasound energy. We assessed whether non-gas filled colloidal solutions (hyperoncotic medium molecular hydroxyethyl starch and degraded gelatin polypeptides) will facilitate clot disruption by ultrasound. In two separate experiments human blood clots, 200-400 mg in weight, were weighed and then immersed for 15 seconds in 10 ml normal saline solution containing 0%, 0.1%, 1%, 2%, and 5% of hyperoncotic medium molecular hydroxyethyl starch or 0%, 0.035%, 0.175%, 0.35%, and 0.7% degraded gelatin polypeptides. Clots were randomized to 10 seconds 20 kHz ultrasound or immersion without ultrasound. After treatment, the clots were reweighed, and the percent difference in weight was calculated. Non-gas filled microparticle-containing solutions such as hyperoncotic medium molecular hydroxyethyl starch and degraded gelatin polypeptides significantly augmented blood clot disruption by ultrasound. The effect is dependent on the colloidal solution concentration with maximal effect achieved with 1% hyperoncotic medium molecular hydroxyethyl starch and 0.35% degraded gelatin polypeptides.

Does intraoperative hetastarch administration increase blood loss and transfusion requirements after cardiac surgery?

Hetastarch is used for intravascular volume expansion in cardiac surgery. Studies show conflicting effects of intraoperative hetastarch administration on postoperative bleeding. Hetastarch was routinely used for volume expansion during cardiovascular surgeries at our institution until its use was discontinued intraoperatively. We performed a retrospective chart review on patients undergoing primary coronary artery bypass grafting, valve repair or replacement requiring cardiopulmonary bypass (n = 444), 234 of which received intraoperative hetastarch and 210 did not. There was no difference in demographics, cardiac surgery, or cardiopulmonary bypass duration between the two groups. Blood loss for 0-4 h postoperatively was 377 +/- 244 mL in the group not receiving hetastarch compared with 515 +/- 336 mL in the group that received hetastarch (P < 0.001). For 0-24 h postoperatively, blood loss was 923 +/- 473 mL versus 1,283 +/- 686 mL in the absence and presence of hetastarch, respectively (P < 0.001). Allogeneic transfusion requirements (cryoprecipitate, fresh frozen plasma, and platelets) were larger in the hetastarch group (all P < 0.001). Nearly all (99%) patients in the hetastarch group received less than the manufacturer's recommended dose (20 mL/kg) of hetastarch.

IMPLICATIONS

Our large retrospective study suggests that intraoperative use of hetastarch in primary cardiac surgery with cardiopulmonary bypass may increase bleeding and transfusion requirements. A large prospective study is needed to determine if intraoperative administration of hetastarch should be avoided during cardiovascular surgery.

Activity of blood coagulation and fibrinolysis during and after hydroxyethyl starch (HES) colloidal volume replacement

OBJECTIVES

To examine the effect of medium molecular weight hydroxyethyl starch on protein C levels and the changes in the activation state of blood platelets, coagulation and fibrinolyis during and after 5 day of its infusion.

DESIGN AND METHODS

Fifty male patients (mean age: 47 years, range 45-50 years) who required prostatectomy for benign prostatic hyperplasia were divided into two equal groups. One group was given 15 mL/kg body weight (mean volume 1000 mL +/- 100 mL) of 6% hydroxyethyl starch (HES) 200/0.5, the other received an equal volume of 5% human albumin during the operation. Blood samples were collected immediately before infusion (baseline values) and at 20, 40, 60, 90, 240, and 480 min after the infusion started then daily for the next 5 days postoperatively. Hematocrit, factor VIII:C, thrombin-antithrombin III complex; the anticoagulant protein C levels; the fibrinolytic parameters tissue type plasminogen activator (t-PA), and the fibrinolytic product D-Dimer and the platelet aggregation activity were measured.

RESULTS

The data obtained did not detect any significant differences between HES and human albumin in the plasma levels of thrombin-antithrombin III complex, protein C, tissue-type plasminogen activator and the fibrin split products D-Dimer. Factor VIII:C and platelet aggregation were significantly lower in the hydroxyethyl starch group in comparison with albumin. Baseline values were attained postoperatively for factor VIII:C and platelet aggregation by the first and fifth days, respectively.

CONCLUSION

The lowering effect of medium molecular weight hydroxyethyl starch on factor VIII:C would not be attributed to increased proteolytic activity of protein C on this coagulation cofactor because there is a nonsignificant change in protein C levels.

Reappraising the prehospital care of the patient with major trauma

Recent research efforts have demonstrated that many long-standing practices for the prehospital resuscitation of trauma patients may be inappropriate, particularly in certain circumstances. Traditional practices, such as application of antishock garments and IV fluid administration, may even be detrimental in certain patients with uncontrolled bleeding. Endotracheal intubation, although potentially capable of prolonging a patient's ability to tolerate circulatory arrest, may be harmful if overzealous ventilation further compromises cardiac output in such severe hemodynamic instability. If these procedures delay patient transport, any benefit they may offer could be outweighed by delaying definitive care. To improve current systems of trauma care, future trauma research must address the different mechanisms of injury, the anatomic areas involved, and the physiologic staging in a given patient.

Intraoperative hetastarch infusion impairs hemostasis after cardiac operations

BACKGROUND

An outbreak of excessive bleeding after cardiac operations occurred at our institution when 5% albumin was in short supply and hetastarch became the preferred intraoperative colloid. As hetastarch may impair coagulation, we investigated the effects of its intraoperative administration on post-cardiac surgical hemostasis.

METHODS

Indices of postoperative hemostasis were analyzed in 189 consecutive patients undergoing coronary artery bypass grafting. Three groups were compared: one group (n = 68) received a mean of 796 mL of hetastarch only in the operating room (a few minutes after cessation of cardiopulmonary bypass), another group (n = 59) received a mean of 856 mL postoperatively only, and a third group (n = 62) received no hetastarch.

RESULTS

Compared with the other two groups, those patients administered hetastarch intraoperatively exhibited significant reductions in hematocrit and platelet count, a significant prolongation in the prothrombin time, and significant increases in both blood loss and hemostatic drug requirement. Also identified were obvious trends toward a greater transfusion requirement and reexploration rate for bleeding in the latter group.

CONCLUSIONS

Hetastarch infusion just after weaning from cardiopulmonary bypass produces a clinically important impairment in post-cardiac surgical hemostasis. Intraoperative use of this agent during heart operations should be avoided until the safe timing of its administration is clarified.

Comparison of hetastarch with albumin for postoperative volume expansion in children after cardiopulmonary bypass

OBJECTIVE

Hetastarch has been studied as a volume expander in adults after cardiopulmonary bypass (CPB) and in recommended dosages has not altered coagulation studies or increased clinical bleeding. Hetastarch was compared with albumin in children after CPB to determine whether hetastarch use was associated with increased clinical bleeding or alteration of coagulation studies.

DESIGN

Randomized double-blinded study.

SETTING

University-affiliated children's hospital.

PARTICIPANTS

Forty-seven children age 1 year or greater (mean 72.8 months; range 12 months to 15.5 years) scheduled for repair of congenital heart disease with moderate hypothermia were randomized to receive hetastarch or albumin as a postoperative volume expander during the first 24 hours after surgery.

INTERVENTIONS

Thirty-eight children required colloid replacement therapy. Blood pressure, central venous pressure, urine output, and chest tube drainage were used to determine colloid requirement.

MEASUREMENTS AND MAIN RESULTS

Clinical bleeding and laboratory studies of coagulation were evaluated as were requirements for colloid, crystalloid, and blood products. Twenty children received 6% hetastarch, and 18 received 5% albumin. No differences were found in the amount of replacement fluids required, or in coagulation parameters in children receiving 20 mL/kg or less of either colloid replacement therapy. An increase in prothrombin time was demonstrated in children who received greater than 20 mL/kg of 6% hetastarch (p = 0.006); however, no difference in clinical bleeding or blood product requirement was demonstrated between the hetastarch or albumin groups receiving more than 20 mL/kg.

CONCLUSION

This study demonstrated that 6% hetastarch is safe and an effective plasma volume expander in the postoperative management of children, using volumes up to 20 mL/kg. Close laboratory monitoring and careful evaluation of clinical bleeding are suggested when larger doses of hetastarch are administered because of prolongation of the prothrombin time with more than 20 mL/kg of hetastarch.

Volume loading with hypertonic saline solution: endocrinologic and circulatory responses

Hypertonic saline solution appears to be an attractive method of volume expansion. In 45 patients undergoing elective aorto-coronary bypass grafting, endocrinologic and circulatory responses to volume loading with hypertonic saline solution prepared in low molecular weight (MW) hydroxyethyl starch (HES) solution (72 g/L NaCl, HES concentration: 6%; MW: 200,000 D; degree of substitution [DS]: 0.5) (HS-HES) was compared randomly to patients who had received low molecular weight HES solution (LMW-HES). A group of patients without volume loading served as a control. Volume was infused to double the low pulmonary capillary wedge pressure (PCWP < 5 mmHg) after induction of anesthesia. Plasma levels of atrial natriuretic peptide (ANP), endothelin, vasopressin, and catecholamines were measured before, during, and after cardiopulmonary bypass (CPB) until the first postoperative day. In addition to systemic circulatory changes, capillary skin blood flow was measured by laser Doppler flowmetry. ANP plasma concentration increased in both volume groups (HS-HES: +79%; HES: +32%), whereas it decreased in the control (-20%). Infusion of HS-HES resulted in an increase in plasma endothelin concentration before and after CPB (from 3 to 6 pg/mL). Five hours after CPB, both treatment groups had higher endothelin plasma concentrations than the control patients (P < 0.05). Epinephrine and norepinephrine plasma levels increased most markedly in the control patients and were highest in the postbypass period in these patients. CI increased most after infusion of HS-HES (+65%) (P < 0.05). In the postbypass period, CI remained significantly higher in both volume groups than in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of hetastarch as adjunct therapy in 26 dogs with hypoalbuminemia: a phase two clinical trial

The purpose of this study was to evaluate the safety and efficacy of the synthetic colloid hetastarch in dogs with hypoalbuminemia. Individual doses of hetastarch ranged from 9 to 27 mL/kg, and multiple doses were used frequently. Total doses ranged from 9 to 59 mL/kg. Colloid oncotic pressure was measured in 13 dogs before and after treatment. Mean colloid oncotic pressure +/- SD was 9.32 +/- 2.35 mm Hg before treatment and 16.41 +/- 1.61 mm Hg in 8 healthy pet dogs used as controls. The difference in these values was significant (P < .001). There was a significant increase in mean colloid oncotic pressure after the first dose of hetastarch, but there was no relationship between the dose of hetastarch and the magnitude of increase in colloid oncotic pressure. Peripheral edema or body cavity transudates resolved or decreased in 83% of the dogs despite concurrent use of crystalloid fluid therapy. There was also no relationship between the dose of hetastarch and resolution of edema. Worsening of the results from coagulograms occurred in 5 of 18 dogs, and included increased prothrombin time (n = 1), increased partial thromboplastin time (n = 5), and decreased platelet count (n = 3). Bleeding that occurred in 3 dogs could not be directly attributed to the hetastarch. There was no relationship between the dose of hetastarch and worsening of the values in the coagulograms.

Hydroxyethyl starch as a prime for cardiopulmonary bypass: effects of two different solutions on haemostasis

Hydroxyethyl starch (HES) is efficacious as a volume expander in cardiac surgical patients, but it may impair the haemostatic mechanisms. However, this latter effect may be less conspicuous with low molecular weight (LMW) solutions than with high molecular weight (HMW) solutions. Therefore, LMW- and HMW-HES solutions were evaluated as priming solutions for cardiopulmonary bypass (CPB) with respect to their effect on haemostasis. Forty-five patients undergoing coronary bypass grafting were prospectively randomised to three groups and received in a double-blind manner as their CPB prime either 20 ml.kg-1 LMW-HES (Mw 120,000), 20 ml.kg-1 HMW-HES (Mw 400,000) or Ringer's acetate 2000 ml. The final volume of the prime was completed to 2000 ml with Ringer's acetate in the HES groups. Anaesthesia and CPB management were standardised. Plasma levels of von Willebrand factor antigen and factor VIII procoagulant activity were significantly more depressed after CPB in both HES-groups as compared with the crystalloid prime group. In addition, APTT was more prolonged and the maximal amplitude of thromboelastographic tracing was more decreased in the HES-groups. It is concluded that it may be advisable to avoid HES solutions in the CPB prime, especially in patients with an increased risk for bleeding after cardiac operations.

A cluster of severe postoperative bleeding following open heart surgery

OBJECTIVE

To investigate a cluster of postoperative bleeding following open heart surgery.

DESIGN

A cohort and case/control study.

SETTING

Palo Alto Veterans Administration Medical Center, Palo Alto, California.

PARTICIPANTS

Six (21.4%) of 28 patients undergoing open heart surgery who developed severe, nonsurgical, postoperative bleeding from July 1 through August 30, 1988 (outbreak period). All case-patients had chest tube drainage of greater than or equal to 1000 ml within 4 hours of surgery but did not have identifiable bleeding vessel(s) on exploration.

RESULTS

Upon comparison of the pre-outbreak (January 1986 through June 1988) and the outbreak period, a significant increase was found in the incidence of postoperative nonsurgical bleeding (5/440 versus 6/28, p = .0006), but not of postoperative surgical bleeding (8/440 versus 0/28, p = 1.0). Of all patients undergoing open heart surgery during the outbreak period, case patients were found to be older (67.8 versus 60.6, p = .02) and to have received a larger volume of hetastarch (HES), a synthetic colloidal plasma-volume expander (mean = 19.4 ml/kg versus 14.1 ml/kg, p = .02).

CONCLUSIONS

We conclude that the use of large volumes of HES during surgery in the elderly open heart surgery patient may increase the risk for severe, nonsurgical postoperative bleeding, probably caused by alterations of the coagulation system. As the incidence of open heart surgery increases among the elderly, surgeons and anesthesiologists should be alert to possible adverse reactions from exposures not associated with adverse reactions in younger patients.