New Light on Intravascular Volume Replacement Regimens: What Did We Learn from the Past Three Years?

Patient Management Strategies in Perioperative, Intraoperative, and Postoperative Period in Breast Reconstruction With DIEP-Flap: Clinical Recommendations

Background and Objective

Deep Inferior Epigastric Perforator (DIEP) flap is a tissue isolated from the skin and subcutaneous tissue of the lower abdomen or rectus muscle to foster breast reconstruction. There is limited information about DIEP-flap induced complications associated with breast reconstruction surgery.

Evidence

We conducted a systematic review of the published literature in the field of breast cancer reconstruction surgery. Information was gathered through internet resources such as PubMed, Medline, eMedicine, NLM, and ReleMed etc. The following key phrases were used for effective literature collection: “DIEP flap”, “Breast reconstruction”, “Patient management”, “Postoperative DIEP”, “Intraoperative anticoagulant therapy”, “Clinical recommendations”. A total of 106 research papers were retrieved pertaining to this systematic review.

Conclusion

A successful breast reconstruction with DIEP-flap without complications is the priority achievement for this surgical procedure. This study provides various evidence-based recommendations on patient management in the perioperative, intraoperative, and postoperative periods. The clinical recommendations provided in this review can benefit surgeons to execute breast reconstruction surgery with minimal postoperative complications. These recommendations are beneficial to improve clinical outcomes when performing surgery by minimizing complications in perioperative, intraoperative, and postoperative period.

Identification of Independent Risk Factors for Complications: A Retrospective Analysis of 163 Fibular Free Flaps for Mandibulofacial Reconstruction

PURPOSE

Fibular free flap transfer is a powerful tool available to the reconstructive surgeon when treating oral and maxillofacial defects, but complications still occasionally occur and predictive analysis focusing on this specific flap is limited in terms of risk factors for complication. The purpose of this study was to identify key variables associated with complications in patients undergoing fibular free flap transfer.

PATIENTS AND METHODS

The data of 163 consecutive patients who underwent fibular free flap surgery at the Department of Oral and Maxillofacial Surgery, Sun Yat-Sen Memorial Hospital of Sun Yat-Sen University, between 2012 and 2015 were reviewed retrospectively. Patient demographic data, laboratory data, surgical data, and fluid infusion-related data that may have an influence on free flap outcomes were recorded. Univariate and multivariate logistic regression analyses were used to identify relevant risk factors.

RESULTS

A total of 163 fibular free flaps were transferred for mandibulofacial reconstruction in 163 patients with a mean age of 50.9 years. Postoperative complications developed in 33 (20.2%). Multivariate analysis showed that free flap complications were significantly associated with radiotherapy history (odds ratio [OR], 5.12; P = .001), postoperative anemia (OR, 1.048; P = .041), postoperative hypoalbuminemia (OR, 0.844; P = .002), and prolonged operative time (OR, 1.005; P = .004).

CONCLUSIONS

Radiotherapy history, decreased postoperative hemoglobin and albumin levels, and prolonged operative time are potential predictors of postoperative complications after fibular free flap reconstruction for mandibulofacial defects.

A Comparison of the Haemodynamic Effects of 4% Succinylated Gelatin, 6% Hydroxyethyl Starch (200/0.5) and 4% Human Albumin after Cardiac Surgery

Background and Aims:

The goal for volume replacement therapy is to maintain stable haemodynamics after cardiac surgery. We hypothesized that a short term infusion of hydroxyethyl starch results in better haemodynamic response than an infusion of lower molecular weight gelatin.

Material and Methods:

45 patients received a predetermined fixed dose of 15 ml kg−1 of either 4% succinylated gelatin (GEL) or 6% hydroxyethyl starch (HES) or 4% human albumin (HA) after cardiac surgery.

Results and Conclusions:

Pulmonary capillary wedge pressure was more increased in GEL and HES groups [mean (SD) 153% (54) and 168% (57) of pre-infusion value] than in HA group [122% (23)] (P = 0.031) after completion of infusion, but no differences in cardiac index (CI) and stroke volume index (SVI) were observed. At 2 and 18 hours after end of study infusions SVI was more increased in HES [143% (38) and 148% (41) of pre-infusion values] and HA [143% (35) and 163% (42) of pre-infusion values] groups than in GEL [116% (23) and 125% (30)] group (P = 0.047 at 2 hours and P = 0.033 at 18 hours). In early postoperative phase after cardiac surgery, HES and HA infusions improve haemodynamics more and longer period than GEL infusion.

Characteristics and intraoperative treatments associated with head and neck free tissue transfer complications and failures

OBJECTIVE

To investigate the association between perioperative patient characteristics and treatment modalities (eg, vasopressor use and volume of fluid administration) with complications and failure rates in patients undergoing head and neck free tissue transfer (FTT).

STUDY DESIGN

A retrospective review of medical records.

SETTING

Perioperative hospitalization for head and neck FTT at 1 tertiary care medical center between January 1, 2009, and October 31, 2011.

SUBJECTS AND METHODS

Consecutive patients (N=235) who underwent head and neck FTT. Demographic, patient characteristic, and intraoperative data were extracted from medical records. Complication and failure rates within the first 30 days were collected

RESULTS

In a multivariate analysis controlling for age, sex, ethnicity, reason for receiving flap, and type and volume of fluid given, perioperative complication was significantly associated with surgical blood loss (P=.019; 95% confidence interval [CI], 1.01-1.16), while the rate of intraoperative fluid administration did not reach statistical significance (P=.06; 95% CI, 0.99-1.28). In a univariate analysis, FTT failure was significantly associated with reason for surgery (odds ratio, 5.40; P=.03; 95% CI, 1.69-17.3) and preoperative diagnosis of coronary artery disease (odds ratio, 3.60; P=.03; 95% CI, 1.16-11.2). Intraoperative vasopressor administration was not associated with either FTT complication or failure rate.

CONCLUSIONS

FTT complications were associated with surgical blood loss but not the use of vasoactive drugs. For patients undergoing FTT, judicious monitoring of blood loss may help stratify the risk of complication and failure.

Selection of priming solutions for cardiopulmonary bypass in adults

The issue of choosing the right priming solution for adult cardiopulmonary bypass patients has been studied and argued for at least three decades. However, there is still no general consensus with regard to making the right choice. Basically, priming solutions can be classified into two categories, i.e. crystalloids and colloids. The former consists of dextrose, balanced crystalloid fluids, and mannitol, and the latter consists of albumin, dextrans, gelatins, and hydroxyethyl starch. In general, crystalloids are simple volume expanding solutions that mimic the normal plasma electrolyte concentrations. They can be used as clear priming solutions resulting in effective hemodilution but they lack oncotic activity. On the contrary, colloids have the advantage in maintaining the colloid oncotic pressure and reducing tissue oedema. However, colloids have been associated with increased incidence of anaphylactoid reactions and clinical coagulopathy. In this paper, we will describe the basic characteristics, the clinical efficiency and the safety of different types of priming fluids and make an overview on how to select the ideal priming solution for cardiopulmonary bypass in adults.

Short-term effectiveness of different volume replacement therapies in postoperative hypovolaemic patients

BACKGROUND AND OBJECTIVE

To examine the kinetics of volume loading with crystalloid and colloid infusions in critically ill patients after major surgery, using the pulse contour cardiac output (PiCCO) monitoring technique.

METHODS

This prospective, randomized, multicentre study of 11 ICUs involved 200 mixed postoperative hypovolaemic patients (50 patients per group) in Hungary. Patients received 10 ml kg of lactated Ringer's solution, succinylated gelatin 4% w/v, 130/0.4 hydroxyethyl starch 6% w/v (HES) or human albumin 5% w/v over 30 min. A complete haemodynamic profile was obtained at 30, 45, 60, 90 and 120 min after baseline. The peak haemodynamic effects, the 120 min changes compared with baseline, the area under the curve (AUC) for the haemodynamic parameters over 120 min and the haemodilution effect of the solutions were analysed. The primary outcome was to compare the AUCs and the secondary outcome was to evaluate the haemodynamic changes at 120 min.

RESULTS

There were significant differences in the AUCs of the haemodynamic parameters between colloids and lactated Ringer's solution in the cardiac index and global end-diastolic volume index (GEDVI); human albumin vs. lactated Ringer's solution in stroke volume variation (SVV); and succinylated gelatin, HES vs. lactated Ringer's solution in the oxygen delivery index (DO2I). Colloid infusions (mainly HES and human albumin) at 120 min caused significant changes in central venous pressure, cardiac index, GEDVI, SVV, DO2I and central venous oxygen saturation compared with baseline. The haemodilution effect was significantly greater in colloids vs. lactated Ringer's solution.

CONCLUSION

In postoperative hypovolaemic patients, lactated Ringer's solution can significantly improve haemodynamics at the end of volume loading, but this effect completely disappears at 120 min. Ten millilitres per kilogram of colloid bolus (especially HES) improved the haemodynamics at 120 min; however, this was by only 5-25% compared with baseline. The colloids caused significantly larger AUCs than lactated Ringer's solution, but only in the cardiac index, GEDVI and DO2I, plus human albumin in the SVV.

Relevance of colloid oncotic pressure regulation during neonatal and infant cardiopulmonary bypass: a prospective randomized study

OBJECTIVE

In neonatal and infant cardiac surgery with cardiopulmonary bypass (CPB), hemodilution with reduction of plasma albumin concentration and low colloid oncotic pressure (COP) are the main factors associated with tissue edema and postoperative weight gain. The aim of our study was to evaluate the influence of two different COP regulatory strategies on post-bypass body weight gain, fluid balance, and clinical outcomes.

METHODS

Seventy elective patients with body weight<10 kg underwent first-time cardiac surgery with CPB and were randomized into two groups. The standard COP group received 0.5 g kg(-1) of human albumin in the priming and, during CPB, albumin was added to maintain the COP>15 mmHg. In the high COP group, albumin concentration in the priming was 5% and, during CPB, the COP was maintained above 18 mmHg. All patients were monitored before, during and until 24h postoperatively. Data were collected on body weight gain, COP, albumin concentration, fluids transfusion, blood loss, urine production and laboratory results.

RESULTS

Patients' demographics and operative data were comparable. Although the high COP group had perioperatively significantly higher COP and albumin concentration than the standard COP group, no significant difference was found in the body weight gain. There were also no significant differences between the groups with respect to fluid balance, urine output and blood loss. However, the high COP group had significantly shorter postoperative duration of mechanical ventilation (10h vs 14 h, p=0.02) and lower plasma lactate concentration post operation (1.1 mmoll(-1) vs 1.4 mmoll(-1), p=0.046).

CONCLUSIONS

The COP regulatory strategy for neonatal and infant CPB, based upon the 5% concentration of albumin in the priming and a COP target of 18 mmHg during bypass, better preserves the plasma albumin concentration within the physiological range and stabilizes the colloid pressure than the standard strategy (0.5 gkg(-1) albumin in the priming and bypass COP target at 15 mmHg). Nevertheless, only the lower postoperative plasma lactate concentration and the shorter duration of mechanical ventilation in the high COP group indicated the potential clinical benefit of this new strategy.

Comparison of the effect of 6% hydroxyethyl starch and gelatine on cardiac and stroke volume index: a randomized, controlled trial after cardiac surgery

BACKGROUND AND AIMS

The objective of this study was to find out the effect of various doses of hydroxyethyl starch (HES), gelatine or Ringer's acetate on cardiac and stroke volume index after cardiac surgery.

MATERIAL AND METHODS

Three consecutive boluses (each 7 mL·kg(-1)) of either 6% HES 130/0.4, 4% gelatine, or Ringer's acetate solutions were administered to 45 patients postoperatively. The rate of infusions was adjusted according to haemodynamic measurements. Thereafter, infusion of the study solution (7 mL·kg(-1)) was continued for the following 12 hours. The total dose of study solution was 28 mL·kg(-1).

RESULTS AND CONCLUSION

Mean (SD) cardiac and stroke volume indices were greater in the HES group [2.8 L·min(-1)·m(-2) (0.7), 34.1 (6.7) ml·m( -2)] than in the gelatine group [2.2 L·min(-1)·m( -2) (0.6), 25.8 (7.2) ml·m(-2)] after completion of 7 mL·kg(-1) of study solution. At this stage, the effect of gelatine did not differ from Ringer's acetate. After completion of 14 mL·kg(-1) and 21 mL·kg(-1) of colloids, similar cardiac and stroke volume indices were observed and the haemodynamic response was better in both colloid groups than in the Ringer's acetate group. No differences between groups were detected on the first postoperative morning. In the early postoperative phase after cardiac surgery, the effect of a single dose of HES solution on the haemodynamics was superior to the effect of gelatine or Ringer's acetate. However, after repeated administration of the study solutions, the haemodynamics in the two colloid groups appeared to be similar, but superior to the Ringer's acetate group.

Hydroxyethyl starch 130/0.4 inhibits production of plasma proinflammatory cytokines and attenuates nuclear factor-kappaB activation and Toll-like receptors expression in monocytes during sepsis

BACKGROUND

Hydroxyethyl starch (HES) is one of the most frequently used plasma substitutes, and could modulate inflammatory response in sepsis. Our aim of this study was to investigate the mechanism of the effect of HES 130/0.4 by studying plasma levels of inflammatory cytokines, nuclear factor-kappaB (NF-kappaB) activation, and Toll-like receptors (TLRs) expression in peripheral monocytes during polymicrobial sepsis.

MATERIALS AND METHODS

Rats with sepsis induced by cecal ligation and puncture (CLP) were treated with HES130/0.4 (7.5, 15, or 30 mL/kg, intravenously); then, rat plasma and monocytes were isolated from blood 5 h later. The plasma level of cytokines (tumor necrosis factor [TNF]-alpha and interleukin [IL]-6), NF-kappaB activity, and mRNA and protein levels of TLRs (TLR2 and TLR4) in peripheral blood monocytes were determined by enzyme-linked immunosorbent assay, electrophoretic mobility shift assay, reverse transcription-polymerase chain reaction, and Western blotting, respectively.

RESULTS

HES130/0.4 dose-dependently reduced the plasma level of TNF-alpha and IL-6 in rats with sepsis. HES130/0.4 also significantly inhibited NF-kappaB activation, and TLRs mRNA and protein levels in peripheral monocytes.

CONCLUSION

During sepsis, HES130/0.4 can down-regulate the inflammatory response, possibly through inhibition of the TLRs/NF-kappaB signaling pathway, and could be one more appropriate plasma substitute in sepsis.

The coagulopathy of trauma: a review of mechanisms

BACKGROUND

Bleeding is the most frequent cause of preventable death after severe injury. Coagulopathy associated with severe injury complicates the control of bleeding and is associated with increased morbidity and mortality in trauma patients. The causes and mechanisms are multiple and yet to be clearly defined.

METHODS

Articles addressing the causes and consequences of trauma-associated coagulopathy were identified and reviewed. Clinical situations in which the various mechanistic causes are important were sought along with quantitative estimates of their importance.

RESULTS

Coagulopathy associated with traumatic injury is the result of multiple independent but interacting mechanisms. Early coagulopathy is driven by shock and requires thrombin generation from tissue injury as an initiator. Initiation of coagulation occurs with activation of anticoagulant and fibrinolytic pathways. This Acute Coagulopathy of Trauma-Shock is altered by subsequent events and medical therapies, in particular acidemia, hypothermia, and dilution. There is significant interplay between all mechanisms.

CONCLUSIONS

There is limited understanding of the mechanisms by which tissue trauma, shock, and inflammation initiate trauma coagulopathy. Acute Coagulopathy of Trauma-Shock should be considered distinct from disseminated intravascular coagulation as described in other conditions. Rapid diagnosis and directed interventions are important areas for future research.

Haemodynamics and Acid-Base Equilibrium after Cardiac Surgery: Comparison of Rapidly Degradable Hydroxythyl Starch Solutions and Albumin

Background:

Stable haemodynamics is often achieved by administration of colloids after cardiac surgery. We conducted a prospective, randomized, open-label study comparing haemodynamics and acid-base equilibrium after infusion of two rapidly degradable hydroxyethyl starch (HES) solutions or human albumin (HA) to cardiac surgical patients.

Materials and Methods:

45 patients received a predetermined fixed dose of 15 ml kg−1 of either 6% HES (MW 130 kDa, n=15), 6% HES (MW 200 kDa, n=15) or 4% HA (MW 69 kDa, n=15) after on-pump cardiac surgery.

Results:

Left ventricular filling pressures assessed using pulmonary artery catheter responded similarly in all groups. Mean (SD) cardiac index was higher in HES130 [3.5 1 min−1 m−2 (0.7)] and HES200 [3.5 1 min−1 m−2 (0.5)] than in HA [2.8 1 min−1 m−2 (0.6)] group after completion of infusion (P=0.002) but no differences were detected at 2 and 18 hours. Oxygen delivery increased in both HES groups but not in HA group. After cessation of infusion base excess was the most negative in HA group. At 2 hours mean (SD) base excess was higher in HWS130 [0 (1.32)] than in HES200 [-1.32 (2.27)] and HA [-2.3 (1.3)] group (P=0.002, between the groups).

Conclusions:

We conclude that the effect of albumin on cardiac performance is inferior than that of HES130 or HES200 in early postoperative phase after cardiac surgery. HES130 induces no alterations in acid-base equilibrium whereas a negative base excess was observed after HA infusion.

Does Hextend impair coagulation compared to 6% hetastarch? An ex vivo thromboelastography study

The objective of this study was to determine if coagulation is different between 6% hetastarch in normal saline (NS) and 6% hetastarch in lactated Ringer's solution (LR), with use of an ex vivo thromboelastography (TEG) model with healthy donated volunteer blood. We simulated hemodilution that occurs during clinical resuscitation of hemorrhagic or hypovolemic shock, using healthy human donor whole blood (WB) ex vivo. Coagulopathy related to low, medium, high, or very high dilution of WB with NS or a high-molecular-weight hetastarch-based plasma expander, 6% hetastarch in NS (HSNS) or 6% hetastarch in lactated Ringer's [Hextend (HSLR)], was analyzed by thromboelastography (TEG). No changes were noted in the TEG profile of undiluted WB controls during the 6-hour period of use (P > 0.95). Dilution with HSNS and HSLR significantly impaired coagulation compared to both WB control and NS. Progressive dilution with NS impaired coagulation but to a lesser extent than colloids (P < 0.01). Low dilution of blood with NS increased clot strength by 12% (not significant; P = 0.097). We conclude that WB containing citrate obtained from healthy donors for TEG analysis yields reproducible data over a minimum of 6 hours. Either hetastarch, when present at concentrations comparable to the manufacturer's maximum recommended dose of 20 mL/kg (equivalent to the high dilution used in these experiments), decreases clot tensile strength to levels associated with an increased risk of bleeding. Substitution of lactated Ringer's for NS in 6% hetastarch appears to offer no advantage in avoiding hemostatic compromise in an in vitro model.

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.

Safety and efficacy of albumin administration in trauma

Albumin is one of the oldest known and studied human proteins. It is characterised by diverse physiological and biochemical properties that render it relevant to many aspects of the disordered vascular and cellular functions after trauma. Apart from the ability to maintain the colloid oncotic pressure, human serum albumin has multiple effects, including antioxidant activity and binding affinity for drugs and toxic substances, inhibition of apoptosis and modulation of trauma-induced inflammatory response. According to the current state of knowledge, there are conflicting results regarding the benefits of albumin administration in critically ill patients. Further investigations are warranted to resolve the continued uncertainty about the safety and efficacy of human serum albumin in specific clinical circumstances and selected populations of severely injured patients.

Liberal Versus Restrictive Fluid Management in Knee Arthroplasty: A Randomized, Double-Blind Study

BACKGROUND

There are few data describing the relationship between amount of perioperative fluid and organ function. In this study we investigated the effects of two levels of intravascular fluid administration ("liberal" versus "restrictive") in knee arthroplasty on physiological recovery as the primary outcome variable.

METHODS

In a double-blind study, 48 ASA I-III patients undergoing fast-track elective knee arthroplasty were randomized to restrictive or liberal perioperative intravascular fluid administration. Patients received a fixed rate infusion of Ringer's lactate solution with a standardized volume of colloid. All other aspects of perioperative management (including anesthesia, preoperative fluid status, and postoperative management) were standardized. Primary outcome variables included pulmonary function (spirometry), exercise capacity ("timed up and go" test), coagulation (Thrombelastograph), postoperative hypoxemia (nocturnal pulse oximetry), postoperative ileus (defecation), and subjective patient recovery (visual analog scales). Hospital stay and complications were also noted.

RESULTS

Fluid guidelines were followed strictly in all patients. Liberal (median 4250 mL, range 3150-5200 mL) compared with restrictive (median 1740 mL, range 1100-2165 mL) intravascular fluid administration led to improved pulmonary function 6 h postoperatively, significant hypercoagulability 24-48 h postoperatively, and reduced incidence of vomiting. There were no overall differences in the other assessed perioperative physiological recovery variables (postoperative hypoxemia, exercise capacity or subjective patient recovery variables). No difference was found in hospital stay (median 4 days in both groups, not significant).

CONCLUSION

A liberal compared to a restrictive intravascular fluid regimen may lead to significant hypercoagulability and a reduction in vomiting, but without differences in other recovery variables or hospital stay after fast-track knee arthroplasty.

Concurrent expansion of plasma volume and left ventricular end-diastolic volume in patients after rapid infusion of 5% albumin and lactated Ringer's solution

STUDY OBJECTIVE

To examine the effects of plasma volume expansion on plasma volume, left ventricular end-diastolic volume (LVEDV), and cardiac index (CI) after rapid fluid infusion, as knowledge of the degree of concordance between plasma and cardiac preload expansion could optimize LVEDV expansion without administering excessive fluid.

DESIGN

Randomized, double-blinded study.

SETTING

Academic community hospital.

PATIENTS

20 patients undergoing elective coronary artery bypass surgery.

INTERVENTIONS

Patients were administered either 5% albumin (5 mL/kg) or lactated Ringer's solution (25 mL/kg) over 30 minutes, just before incision.

MEASUREMENTS

Serial measurements of plasma volume, LVEDV by transesophageal echocardiography, and CI were recorded.

MAIN RESULTS

Albumin expanded plasma volume and LVEDV to a similar degree (11.3% and 13.2%). In contrast, lactated Ringer's solution increased plasma volume more than LVEDV (21.7% vs 14.4%; P = 0.0005). Increased LVEDV significantly but poorly correlated with increased CI (r(2) = 0.2, P < 0.0001) for both fluids. However, LVEDV expansion was brief and returned to baseline or less within 30 minutes for both fluids despite continued plasma volume expansion and increased CI. Correspondingly, rates of decline from peak expansion were significantly faster for LVEDV than plasma volume expansion for both albumin (-1.9% + 1.9%/min vs -0.1% + 0.1%/min; P = 0.0008) and lactated Ringer's (-1.1% + 0.8%/min vs -0.4% + 0.2%/min; P = 0.006).

CONCLUSIONS

Intravenous fluids increased LVEDV to a lesser extent and duration than did plasma volume expansion. Monitoring of LVEDV was a poor guide for fluid administration to maximize CI.

[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.

Bioequivalence Comparison between Hydroxyethyl??Starch??130/0.42/6???:???1 and??Hydroxyethyl Starch??130/0.4/9???:???1

OBJECTIVE

The aim of this study was to investigate whether a recently developed low molecular, low substituted hydroxyethyl starch (HES 130/0.42/6 : 1), altered in molar substitution and C2/C6 ratio, is bioequivalent to the former standard HES preparation (130/0.4/9 : 1).

METHODS

The two HES solutions were infused (60g as a single dose within 30 minutes) in healthy volunteers using a randomised, crossover design. HES serum concentrations were used for computation of pharmacokinetic parameters; area under the concentration-time curve from infusion start until 24 hours thereafter (AUC(24)) and maximum serum concentration (C(max)) were the primary criteria. Haemodilution, colloid osmotic pressure and plasma viscosity were measured as secondary criteria. Pentastarch (HES 200/0.5/5:1) was investigated in the same volunteers and manner during a subsequent period.

RESULTS

Using non-compartmental analysis, significant differences were found for AUC(24) (45.97 +/- 8.97 mg . h/mL vs 58.32 +/- 9.23 mg . h/mL; HES 130/0.42/6 : 1 vs HES 130/0.4/9 : 1) and total apparent clearance (CL; 1.14 +/- 0.4 L/h vs 0.81 +/- 0.34 L/h). C(max) and elimination half-life (t(1/2)) were similar, while the AUC(24), t(1/2) and CL of pentastarch were significantly different from those of low substituted HES solutions.

CONCLUSION

Being equivalent with pentastarch and HES 130/0.4/9 : 1 in terms of colloid osmotic and haemodilution effect, HES 130/0.42/6 : 1 shows the fastest clearance from the circulation.

Prolonged international normalized ratio correlates with a large intravascular fluid balance after major abdominal surgery

We performed a prospective randomized study of 32 patients who had undergone pancreaticoduodenectomy and did not receive blood during and after surgery. The patients were prospectively assigned to two groups related to fluid balance in the immediate postoperative period. Group 1 (14 patients) were maintained at a positive intravascular fluid balance of 0-1000 mL; Group 2 (18 patients) were maintained at a positive balance of 1000-2000 mL. Complete blood counts and coagulation tests (International Normalized Ratio) and activated partial thromboplastin time (aPTT) were performed at three time points: the day before surgery, on arrival at the postanesthesia care unit, and on leaving the postanesthesia care unit (16 h later). There were significant differences in International Normalized Ratio values between the groups with deterioration during the time they were in the postanesthesia care unit but not in aPTT values. Positive correlation was found between the amount of positive fluid balance and International Normalized Ratio prolongation, but not with aPTT, suggesting that restricted intravascular fluid balance is beneficial for preservation of coagulation after major abdominal surgery.

Molar substitution and C2/C6 ratio of hydroxyethyl starch: influence on blood coagulation

BACKGROUND

Development of hydroxyethyl starches (HES) with a low impact on blood coagulation but a long intravascular persistence is of clinical interest. A previous in vitro study showed that low substituted high molecular weight HES does not compromise blood coagulation more than medium molecular weight HES. In the present study we assessed the individual effects on blood coagulation of molar substitution and C2/C6 ratio of a high molecular weight HES.

METHODS

Blood was obtained from 30 healthy patients undergoing elective surgery and mixed with six high molecular weight (700 kDa) HES solutions differing in their molar substitution (0.42 and 0.51) and C2/C6 ratio (2.7, 7 and 14) to achieve 20, 40 and 60% dilution. Blood coagulation was assessed by Thrombelastograph analysis (TEG) and plasma coagulation tests. Data were compared using a three-way analysis of variance model with repeated measures on the three factors.

RESULTS

Higher molar substitution compromised blood coagulation most (for all TEG parameters, P<0.05). The lowest C2/C6 ratio was associated with the lowest effect on blood coagulation; r (P<0.001), angle alpha (P=0.003) and coagulation index (P<0.001). No effect on k and maximum amplitude was observed (P for both >0.50). The higher molar substitution was associated with a lesser increase in PT (P=0.007) and a greater decrease in factor VIII (P=0.010). PTT, functional and antigenic von Willebrand factors were not significantly influenced by molar substitution (P for all >0.20). No significant differences between solutions with the same molar substitution but different C2/C6 ratios were found in plasma coagulation parameters (P for all >0.05).

CONCLUSIONS

TEG analysis indicates that high molecular HES with a molar substitution of 0.42 and a C2/C6 ratio of 2.7 has the lowest effect on in vitro human blood coagulation.

Hydroxyethyl starch 130/0.4 versus modified fluid gelatin for volume expansion in cardiac surgery patients: the effects on perioperative bleeding and transfusion needs

In this prospective, randomized, open controlled study we compared the effects on net red blood cell loss of 6% hydroxyethyl starch 130/0.4 (HES: n = 64) and 3% modified fluid gelatin (GEL: n = 68) administered for intravascular volume management in patients undergoing coronary surgery. Blood losses were calculated from determination of circulating blood volume and measurement of preoperative and postoperative hematocrit. Amount of colloids that could be administered was limited to 50 mL/kg. If additional fluids were required, balanced crystalloid solution was used. Anesthetic and surgical techniques were standardized. Both groups were similar with regard to demographic and intraoperative variables. Total study drug was 48.9 +/- 17.2 mL/kg in the HES group and 48.9 +/- 14.6 mL/kg in the GEL group. Total red blood cell loss was 544 +/- 305 mL in the HES group and 504 +/- 327 mL the GEL group. Measured blood losses were also similar in both groups (HES, 19.4 +/- 12.3 mL/kg; GEL, 19.2 +/- 14.5 mL/kg). Exposure to allogeneic blood product was comparable in both groups. In the conditions of the present study, HES 130/0.4 up to 50 mL/kg is a valuable alternative to modified fluid gelatin for plasma volume expansion during and after cardiac surgery.

A triple-blinded randomized trial comparing the hemostatic effects of large-dose 10% hydroxyethyl starch 264/0.45 versus 5% albumin during major reconstructive surgery

In Canada, hydroxyethyl starch 264/0.45 (HES 264/0.45; molar weight 264 kDa, molar substitution 0.45) has largely replaced albumin as the colloidal fluid of choice for perioperative intravascular volume expansion. The maximum recommended dose of HES 264/0.45 is 28 mL/kg; however, there are no clinical data supporting this limit. In this study we compared the hemostatic effects of HES 264/0.45 versus 5% albumin in doses up to 45 mL/kg over 24 h during major reconstructive head and neck surgery. Fifty patients were randomized to receive HES 264/0.45 or 5% human albumin from the induction of anesthesia until 24 h thereafter. Both albumin and HES 264/0.45 effectively maintained physiologic variables in the perioperative and postoperative periods. The partial thromboplastin time and international normalized ratio were significantly increased in the HES 264/0.45 group compared with the albumin group after infusion of 30 mL/kg and 45 mL/kg (P < 0.05). Factor VIII activity and von Willebrand factor level were significantly reduced in the HES 264/0.45 group compared with the albumin group after infusion of 15 mL/kg, 30 mL/kg, and 45 mL/kg (P < 0.05). Significantly more subjects in the HES 264/0.45 group received allogeneic red blood cell transfusions (P < 0.02). We conclude that HES 264/0.45 infusions >30 mL/kg over 24 h impair coagulation to a greater extent than albumin, possibly leading to more allogeneic transfusions.

Molecular weight of hydroxyethyl starch: is there an effect on blood coagulation and pharmacokinetics? ‡ ‡Declaration of interest. This study was funded in part by B. Braun, of which MB and AF are employees and DS is a paid consultant. B. Braun has funded other research in this department in the past, as have other competitor companies

BACKGROUND

The development of hydroxyethyl starches (HES) with low impact on blood coagulation but higher volume effect compared with the currently used HES solutions is of clinical interest. We hypothesized that high molecular weight, low-substituted HES might possess these properties.

METHODS

Thirty pigs were infused with three different HES solutions (20 ml kg(-1)) with the same degree of molar substitution (0.42) but different molecular weights (130, 500 and 900 kDa). Serial blood samples were taken over 24 h and blood coagulation was assessed by Thromboelastograph analysis and analysis of plasma coagulation. In addition, plasma concentration and in vivo molecular weight were determined and pharmacokinetic data were computed based on a two-compartment model.

RESULTS

Thromboelastograph analysis and plasma coagulation tests did not reveal a more pronounced alteration of blood coagulation with HES 500 and HES 900 compared with HES 130. In contrast, HES 500 and HES 900 had a greater area under the plasma concentration-time curve [1542 (142) g min litre(-1), P<0.001, 1701 (321) g min litre(-1), P<0.001] than HES 130 [1156 (223) g min litre(-1)] and alpha half life (t(alpha)(1/2)) was longer for HES 500 [53.8 (8.6) min, P<0.01] and HES 900 [57.1 (12.3) min, P<0.01] than for HES 130 [39.9 (10.7) min]. Beta half life (t(beta)(1/2)), however, was similar for all three types of HES [from 332 (100) to 381 (63) min].

CONCLUSIONS

In low-substituted HES, molecular weight is not a key factor in compromising blood coagulation. The longer initial intravascular persistence of high molecular weight low-substituted HES might result in a longer lasting volume effect.

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.

A comparison of albumin and saline for fluid resuscitation in the intensive care unit

BACKGROUND

It remains uncertain whether the choice of resuscitation fluid for patients in intensive care units (ICUs) affects survival. We conducted a multicenter, randomized, double-blind trial to compare the effect of fluid resuscitation with albumin or saline on mortality in a heterogeneous population of patients in the ICU.

METHODS

We randomly assigned patients who had been admitted to the ICU to receive either 4 percent albumin or normal saline for intravascular-fluid resuscitation during the next 28 days. The primary outcome measure was death from any cause during the 28-day period after randomization.

RESULTS

Of the 6997 patients who underwent randomization, 3497 were assigned to receive albumin and 3500 to receive saline; the two groups had similar baseline characteristics. There were 726 deaths in the albumin group, as compared with 729 deaths in the saline group (relative risk of death, 0.99; 95 percent confidence interval, 0.91 to 1.09; P=0.87). The proportion of patients with new single-organ and multiple-organ failure was similar in the two groups (P=0.85). There were no significant differences between the groups in the mean (+/-SD) numbers of days spent in the ICU (6.5+/-6.6 in the albumin group and 6.2+/-6.2 in the saline group, P=0.44), days spent in the hospital (15.3+/-9.6 and 15.6+/-9.6, respectively; P=0.30), days of mechanical ventilation (4.5+/-6.1 and 4.3+/-5.7, respectively; P=0.74), or days of renal-replacement therapy (0.5+/-2.3 and 0.4+/-2.0, respectively; P=0.41).

CONCLUSIONS

In patients in the ICU, use of either 4 percent albumin or normal saline for fluid resuscitation results in similar outcomes at 28 days.