Intravascular Volume Therapy With Colloids in Cardiac Surgery

Perioperative fluid management: evidence-based consensus recommendations from the international multidisciplinary PeriOperative Quality Initiative

Fluid therapy is an integral component of perioperative management. In light of emerging evidence in this area, the Perioperative Quality Initiative (POQI) convened an international multiprofessional expert meeting to generate evidence-based consensus recommendations for fluid management in patients undergoing surgery. This article provides a summary of the recommendations for perioperative fluid management of surgical patients from the preoperative period until hospital discharge and for all types of elective and emergency surgery, apart from burn injuries and head and neck surgery. Where evidence was lacking, recommendations for future research were generated. Specific recommendations are made for fluid management in elective major noncardiac surgery, cardiopulmonary bypass, thoracic surgery, neurosurgery, minor noncardiac surgery under general anaesthesia, and critical illness. There are ongoing gaps in knowledge resulting in variation in practice and some disagreement with our consensus recommendations. Perioperative fluid management should be individualised, taking into account the type of surgery and important patient factors, including intravascular volume status and acute and chronic comorbidities. Recommendations are made for further research in perioperative fluid management to address important gaps.

Magnetically Driven Soft Continuum Microrobot for Intravascular Operations in Microscale

Remotely controlled soft continuum robots with active steering capability have broad prospects in medical applications. However, conventional continuum robots have the miniaturization challenge. This paper presents a microscale soft continuum microrobot with steering and locomotion capabilities based on magnetic field actuation. The magnetically driven soft continuum microrobot is made of NdFeB particles and polydimethylsiloxane (PDMS), and it can be as small as 200 μm in diameter. Moreover, a hydrogel layer is covered on the surface of the microrobot, which not only overcomes the adhesion force between the microobjects and the soft tip but also reduces the friction between the microrobot and substrate. The performance test indicates the soft continuum microrobot featured excellent control and steering capabilities. The experimental results demonstrate that the soft continuum microrobot can travel through the microfluidic channel by its own vibration and flexibly steer in a bifurcation environment. Moreover, the micromanipulation of microbeads in the microfluidic channels proves that the proposed microscale soft continuum microrobot has a great potential for intravascular manipulation.

Albumin in adult cardiac surgery: a narrative review

PURPOSE

Intravascular fluids are a necessary and universal component of cardiac surgical patient care. Both crystalloids and colloids are used to maintain or restore circulating plasma volume and ensure adequate organ perfusion. In Canada, human albumin solution (5% or 25% concentration) is a colloid commonly used for this purpose. In this narrative review, we discuss albumin supply in Canada, explore the perceived advantages of albumin, and describe the clinical literature supporting and refuting albumin use over other fluids in the adult cardiac surgical population.

SOURCE

We conducted a targeted search of PubMed, Embase, Medline, Web of Science, ProQuest Dissertations and Theses Global, the Cochrane Central Register of Controlled trials, and the Cochrane Database of Systematic Reviews. Search terms included albumin, colloid, cardiac surgery, bleeding, hemorrhage, transfusion, and cardiopulmonary bypass.

PRINCIPAL FINDINGS

Albumin is produced from fractionated human plasma and imported into Canada from international suppliers at a cost of approximately $21 million CAD per annum. While it is widely used in cardiac surgical patients across the country, it is approximately 30-times more expensive than equivalent doses of balanced crystalloid solutions, with wide inter-institutional variability in use and no clear association with improved outcomes. There is a general lack of high-quality evidence for the superiority of albumin over crystalloids in this patient population, and conflicting evidence regarding safety.

CONCLUSIONS

In cardiac surgical patients, albumin is widely utilized despite a lack of high- quality evidence supporting its efficacy or safety. A well-designed randomized controlled trial is needed to clarify the role of albumin in cardiac surgical patients.

Albumin Use After Cardiac Surgery

Objectives

To investigate the effect of albumin exposure in ICU after cardiac surgery on hospital mortality, complications, and costs.

Design

A retrospective, single-center cohort study with economic evaluation.

Setting

Cardiothoracic ICU in Australia.

Patients

Adult patients admitted to the ICU after cardiac surgery.

Interventions

None.

Measurements and Main Results

Comparison of outcomes and costs in ICU after cardiac surgery based on 4% human albumin exposure. During the study period, 3,656 patients underwent cardiac surgery. After exclusions, 2,594 patients were suitable for analysis. One-thousand two-hundred sixty-four (48.7%) were exposed to albumin and 19 (1.4%) of those died. The adjusted hospital mortality of albumin exposure compared with no albumin was not significant (odds ratio, 1.24; 95% CI, 0.56-2.79; p = 0.6). More patients exposed to albumin returned to the operating theater for bleeding and/or tamponade (6.1% vs 2.1%; odds ratio, 2.84; 95% CI, 1.81-4.45; p < 0.01) and received packed red cell transfusions (p < 0.001). ICU and hospital lengths of stay were prolonged in those exposed to albumin (mean difference, 18 hr; 95% CI, 10.3-25.6; p < 0.001 and 87.5 hr; 95% CI, 40.5-134.6; p < 0.001). Costs (U.S. dollar) were higher in patients exposed to albumin, compared with those with no albumin exposure (mean difference in ICU costs, $2,728; 95% CI, $1,566-3,890 and mean difference in hospital costs, $5,427; 95% CI, $3,294-7,560).

Conclusions

There is no increased mortality in patients who are exposed to albumin after cardiac surgery. The patients exposed to albumin had higher illness severity, suffered more complications, and incurred higher healthcare costs. A randomized controlled trial is required to determine whether albumin use is effective and safe in this setting.

Fluid resuscitation practices in cardiac surgery patients in the USA: a survey of health care providers

Background

Fluid resuscitation during cardiac surgery is common with significant variability in clinical practice. Our goal was to investigate current practice patterns of fluid volume expansion in patients undergoing cardiac surgeries in the USA.

Methods

We conducted a cross-sectional online survey of 124 cardiothoracic surgeons, cardiovascular anesthesiologists, and perfusionists. Survey questions were designed to assess clinical decision-making patterns of intravenous (IV) fluid utilization in cardiovascular surgery for five types of patients who need volume expansion: (1) patients undergoing cardiopulmonary bypass (CPB) without bleeding, (2) patients undergoing CPB with bleeding, (3) patients undergoing acute normovolemic hemodilution (ANH), (4) patients requiring extracorporeal membrane oxygenation (ECMO) or use of a ventricular assist device (VAD), and (5) patients undergoing either off-pump coronary artery bypass graft (OPCABG) surgery or transcatheter aortic valve replacement (TAVR). First-choice fluid used in fluid boluses for these five patient types was requested. Descriptive statistics were performed using Kruskal-Wallis test and follow-up tests, including t tests, to evaluate differences among respondent groups.

Results

The most commonly preferred indicators of volume status were blood pressure, urine output, cardiac output, central venous pressure, and heart rate. The first choice of fluid for patients needing volume expansion during CPB without bleeding was crystalloids, whereas 5% albumin was the most preferred first choice of fluid for bleeding patients. For volume expansion during ECMO or VAD, the respondents were equally likely to prefer 5% albumin or crystalloids as a first choice of IV fluid, with 5% albumin being the most frequently used adjunct fluid to crystalloids. Surgeons, as a group, more often chose starches as an adjunct fluid to crystalloids for patients needing volume expansion during CPB without bleeding. Surgeons were also more likely to use 25% albumin as an adjunct fluid than were anesthesiologists. While most perfusionists reported using crystalloids to prime the CPB circuit, one third preferred a mixture of 25% albumin and crystalloids. Less interstitial edema and more sustained volume expansion were considered the most important colloid traits in volume expansion.

Conclusions

Fluid utilization practice patterns in the USA varied depending on patient characteristics and clinical specialties of health care professionals.

Electronic supplementary material

The online version of this article (10.1186/s13741-017-0071-6) contains supplementary material, which is available to authorized users.

Postoperative Acute Kidney Injury and Blood Product Transfusion After Synthetic Colloid Use During Cardiac Surgery

OBJECTIVES

This study assessed the effect of 2 types of hydroxyethyl starches (HES) on renal integrity and blood transfusion in cardiac surgery patients.

DESIGN

Retrospective investigation.

SETTING

Patients from a single tertiary medical center.

PARTICIPANTS

Inclusion criteria included coronary artery bypass graft (CABG) and/or valve surgery that included cardiopulmonary bypass with aortic cross-clamping.

INTERVENTIONS

Intraoperative HES and blood product administration.

MEASUREMENTS AND MAIN RESULTS

The study comprised 1,265 patients who met inclusion criteria. Of these patients, 70% received HES, and of these, 47% received<1,000 mL and 53% received≥1,000 mL. There was no difference in the development of acute kidney injury between the 2 groups. A parsimonious propensity model for colloids showed that combined CABG and valve surgery were less likely to be associated with HES administration than was CABG alone (OR 0.68, confidence interval [CI] 0.46-0.97; p = 0.04). Intra-aortic balloon pump use was less likely to be associated with HES administration (OR 0.57, CI 0.38-0.86; p = 0.007). Patients with chronic kidney disease, stages 3 to 5, were less likely to receive HES, with an OR of 0.56 (CI 0.38-0.84; p = 0.004); 0.51 (CI 0.20-1.33; p = 0.170); and 0.23 (CI 0.12-0.44; p<0.0001), respectively, for each stage. No difference was noted in red blood cell transfusion. However, fresh frozen plasma, cryoprecipitate, and platelet transfusions were significantly higher with larger volumes of HES, with an OR of 2.03 (CI 1.64-2.52; p<0.001); 1.60 (CI 1.30-1.97; p<0.000); and 1.62 (CI 1.21-2.15; p = 0.006), respectively. No differences in surgical mortality were found between the colloid and noncolloid groups.

CONCLUSIONS

This study showed no association of postoperative acute kidney injury and red blood cell transfusion between the colloid and noncolloid groups. Although the complication rate was higher with HES administration, there was no difference in surgery mortality between the 2 groups.

Colloids versus crystalloids for fluid resuscitation in critically ill patients

BACKGROUND

Colloid solutions are widely used in fluid resuscitation of critically ill patients. There are several choices of colloid, and there is ongoing debate about the relative effectiveness of colloids compared to crystalloid fluids.

OBJECTIVES

To assess the effects of colloids compared to crystalloids for fluid resuscitation in critically ill patients.

SEARCH METHODS

We searched the Cochrane Injuries Group Specialised Register (17 October 2012), the Cochrane Central Register of Controlled Trials (The Cochrane Library) (Issue 10, 2012), MEDLINE (Ovid) 1946 to October 2012, EMBASE (Ovid) 1980 to October 2012, ISI Web of Science: Science Citation Index Expanded (1970 to October 2012), ISI Web of Science: Conference Proceedings Citation Index-Science (1990 to October 2012), PubMed (October 2012), www.clinical trials.gov and www.controlled-trials.com. We also searched the bibliographies of relevant studies and review articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of colloids compared to crystalloids, in patients requiring volume replacement. We excluded cross-over trials and trials involving pregnant women and neonates.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and rated quality of allocation concealment. We analysed trials with a 'double-intervention', such as those comparing colloid in hypertonic crystalloid to isotonic crystalloid, separately. We stratified the analysis according to colloid type and quality of allocation concealment.

MAIN RESULTS

We identified 78 eligible trials; 70 of these presented mortality data.COLLOIDS COMPARED TO CRYSTALLOIDS: Albumin or plasma protein fraction - 24 trials reported data on mortality, including a total of 9920 patients. The pooled risk ratio (RR) from these trials was 1.01 (95% confidence interval (CI) 0.93 to 1.10). When we excluded the trial with poor-quality allocation concealment, pooled RR was 1.00 (95% CI 0.92 to 1.09). Hydroxyethyl starch - 25 trials compared hydroxyethyl starch with crystalloids and included 9147 patients. The pooled RR was 1.10 (95% CI 1.02 to 1.19). Modified gelatin - 11 trials compared modified gelatin with crystalloid and included 506 patients. The pooled RR was 0.91 (95% CI 0.49 to 1.72). (When the trials by Boldt et al were removed from the three preceding analyses, the results were unchanged.) Dextran - nine trials compared dextran with a crystalloid and included 834 patients. The pooled RR was 1.24 (95% CI 0.94 to 1.65). COLLOIDS IN HYPERTONIC CRYSTALLOID COMPARED TO ISOTONIC CRYSTALLOID: Nine trials compared dextran in hypertonic crystalloid with isotonic crystalloid, including 1985 randomised participants. Pooled RR for mortality was 0.91 (95% CI 0.71 to 1.06).

AUTHORS' CONCLUSIONS

There is no evidence from randomised controlled trials that resuscitation with colloids reduces the risk of death, compared to resuscitation with crystalloids, in patients with trauma, burns or following surgery. Furthermore, the use of hydroxyethyl starch might increase mortality. As colloids are not associated with an improvement in survival and are considerably more expensive than crystalloids, it is hard to see how their continued use in clinical practice can be justified.

Colloids versus crystalloids for fluid resuscitation in critically ill patients

BACKGROUND

Colloid solutions are widely used in fluid resuscitation of critically ill patients. There are several choices of colloid and there is ongoing debate about the relative effectiveness of colloids compared to crystalloid fluids.

OBJECTIVES

To assess the effects of colloids compared to crystalloids for fluid resuscitation in critically ill patients.

SEARCH METHODS

We searched the Cochrane Injuries Group Specialised Register (searched 16 March 2012), Cochrane Central Register of Controlled Trials 2011, issue 3 (The Cochrane Library), MEDLINE (Ovid) 1946 to March 2012, Embase (Ovid) 1980 to March 2012, ISI Web of Science: Science Citation Index Expanded (1970 to March 2012), ISI Web of Science: Conference Proceedings Citation Index-Science (1990 to March 2012), PubMed (searched 16 March 2012), www.clinical trials.gov and www.controlled-trials.com. We also searched the bibliographies of relevant studies and review articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of colloids compared to crystalloids, in patients requiring volume replacement. We excluded cross-over trials and trials in pregnant women and neonates.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and rated quality of allocation concealment. We analysed trials with a 'double-intervention', such as those comparing colloid in hypertonic crystalloid to isotonic crystalloid, separately. We stratified the analysis according to colloid type and quality of allocation concealment.

MAIN RESULTS

We identified 74 eligible trials; 66 of these presented mortality data.Colloids compared to crystalloids Albumin or plasma protein fraction - 24 trials reported data on mortality, including a total of 9920 patients. The pooled relative risk (RR) from these trials was 1.01 (95% confidence interval (CI) 0.93 to 1.10). When we excluded the trial with poor quality allocation concealment, pooled RR was 1.00 (95% CI 0.92 to 1.09). Hydroxyethyl starch - 21 trials compared hydroxyethyl starch with crystalloids, n = 1385 patients. The pooled RR was 1.10 (95% CI 0.91 to 1.32). Modified gelatin - 11 trials compared modified gelatin with crystalloid, n = 506 patients. The pooled RR was 0.91 (95% CI 0.49 to 1.72). (When the trials by Boldt et al were removed from the three preceding analyses, the results were unchanged.) Dextran - nine trials compared dextran with a crystalloid, n = 834 patients. The pooled RR was 1.24 (95% CI 0.94 to 1.65).Colloids in hypertonic crystalloid compared to isotonic crystalloid Nine trials compared dextran in hypertonic crystalloid with isotonic crystalloid, including 1985 randomised participants. Pooled RR was 0.91 (95% CI 0.71 to 1.06).

AUTHORS' CONCLUSIONS

There is no evidence from RCTs that resuscitation with colloids reduces the risk of death, compared to resuscitation with crystalloids, in patients with trauma, burns or following surgery. As colloids are not associated with an improvement in survival, and as they are more expensive than crystalloids, it is hard to see how their continued use in these patients can be justified outside the context of RCTs.