Fluids after cardiac surgery: a pilot study of the use of colloids versus crystalloids. Crit Care Med. 2010;38:2117-2124. [PMID: 20802322 DOI: 10.1097/ccm.0b013e3181f3e08c]

Use of colloids and crystalloids for perioperative clinical infusion management in cardiac surgery patients and postoperative outcomes: a meta-analysis

BACKGROUND

The optimal fluid management strategy for patients undergoing cardiac surgery was controversial regarding fluid volume and intraoperative fluid types. This study aimed to assess the correlation between colloids and crystalloids used for perioperative fluid therapy in cardiac surgery patients and postoperative prognosis.

METHODS

The Ovid MEDLINE(R) ALL, Embase, and Cochrane Central Register of Controlled Trials databases were searched for eligible studies on fluid management strategies using colloids and crystalloids for cardiac surgery patients published before August 25th, 2023.

RESULTS

Ten randomized controlled trials met the eligibility criteria. Compared to the use of crystalloids, the use of colloids, including hydroxyethyl starch (HES), albumin, and gelatine, did not show any differences in mortality, transfusion, acute kidney injury, and atrial fibrillation rates, postoperative blood loss, the length of hospital stay, or the length of intensive care unit (ICU) stay. The results of this meta-analysis showed that the crystalloid group had significantly reduced postoperative chest tube output compared to the colloid group. In the subgroup analysis, the amount of fresh frozen plasma (FFP) infused was significantly lower when using fluid management in the ICU and when using isotonic crystalloids compared to the colloids. In addition, when using fluid management in the ICU, patients in the colloid group had a significant increase in urine volume 24 h after surgery. However, other related factors, including the type of crystalloid solution, type of colloidal solution, and timing of liquid management, did not affect most outcomes.

CONCLUSION

Both colloids and crystalloids could be used as alternatives for perioperative fluid management after cardiac surgery. The use of crystalloids significantly reduced the postoperative chest tube output, and the need for FFP infusion decreased significantly with the use of isotonic crystalloids or fluid management during the ICU stay. ICU patients in the colloid group had higher urine output 24 h after surgery. In addition, although the infusion method was not related to most outcomes, the rates of red blood cell and FFP transfusion and postoperative blood loss in the crystalloid group seemed to be lower, which needed to be further studied in high-quality and large-sample RCTs.

TRIAL REGISTRATION

PROSPERO, CRD42023415234.

Comparison of 4% Albumin and Ringer's Acetate on Hemodynamics in On-pump Cardiac Surgery: An Exploratory Analysis of a Randomized Clinical Trial

OBJECTIVES

Compare hemodynamics between 4% albumin and Ringer's acetate.

DESIGN

Exploratory analysis of the double-blind randomized ALBumin In Cardiac Surgery trial.

SETTING

Single-center study in Helsinki University Hospital.

PARTICIPANTS

We included 1,386 on-pump cardiac surgical patients.

INTERVENTION

We used 4% albumin or Ringer's acetate administration for cardiopulmonary bypass priming, volume replacement intraoperatively and 24 hours postoperatively.

MEASUREMENTS AND MAIN RESULTS

Hypotension (time-weighted average mean arterial pressure of <65 mmHg) and hyperlactatemia (time-weighted average blood lactate of >2 mmol/L) incidences were compared between trial groups in the operating room (OR), and early (0-6 hours) and late (6-24 hours) postoperatively. Associations of hypotension and hyperlactatemia with the ALBumin In Cardiac Surgery primary outcome (≥1 major adverse event [MAE]) were studied. In these time intervals, hypotension occurred in 118, 48, and 17 patients, and hyperlactatemia in 313, 131, and 83 patients. Hypotension and hyperlactatemia associated with MAE occurrence. Hypotension did not differ between the groups (albumin vs Ringer's: OR, 8.8% vs 8.5%; early postoperatively, 2.7% vs 4.2%; late postoperatively, 1.2% vs 1.3%; all p > 0.05). In the albumin group, hyperlactatemia was less frequent late postoperatively (2.9% vs 9.1%; p < 0.001), but not earlier (OR, 22.4% vs 23.6%; early postoperatively, 7.9% vs 11.0%; both p > 0.025 after Bonferroni-Holm correction).

CONCLUSIONS

In on-pump cardiac surgery, hypotension and hyperlactatemia are associated with the occurrence of ≥1 MAE. Compared with Ringer's acetate, albumin did not decrease hypotension and decreased hyperlactatemia only late postoperatively. Albumin's modest hemodynamic effect is concordant with the finding of no difference in MAEs between albumin and Ringer's acetate in the ALBumin In Cardiac Surgery trial.

Heterogeneity of surrogate outcome measures used in critical care studies: A systematic review

BACKGROUND

The choice of outcome measure is a critical decision in the design of any clinical trial, but many Phase III clinical trials in critical care fail to detect a difference between the interventions being compared. This may be because the surrogate outcomes used to show beneficial effects in early phase trials (which informed the design of the subsequent Phase III trials) are not valid guides to the differences between the interventions for the main outcomes of the Phase III trials. We undertook a systematic review (1) to generate a list of outcome measures used in critical care trials, (2) to determine the variability in the outcome reporting in the respiratory subgroup and (3) to create a smaller list of potential early phase endpoints in the respiratory subgroup.

METHODS

Data related to outcomes were extracted from studies published in the six top-ranked critical care journals between 2010 and 2020. Outcomes were classified into subcategories and categories. A subset of early phase endpoints relevant to the respiratory subgroup was selected for further investigation. The variability of the outcomes and the variability in reporting was investigated.

RESULTS

A total of 6905 references were retrieved and a total of 294 separate outcomes were identified from 58 studies. The outcomes were then classified into 11 categories and 66 subcategories. A subset of 22 outcomes relevant for the respiratory group were identified as potential early phase outcomes. The summary statistics, time points and definitions show the outcomes are analysed and reported in different ways.

CONCLUSION

The outcome measures were defined, analysed and reported in a variety of ways. This creates difficulties for synthesising data in systematic reviews and planning definitive trials. This review once again highlights an urgent need for standardisation and validation of surrogate outcomes reported in critical care trials. Future work should aim to validate and develop a core outcome set for surrogate outcomes in critical care trials.

Effects of colloid-based (hydroxyethylstarch 6% 130/0.42, gelafundin 4%) and crystalloid-based volume regimes in cardiac surgery: a retrospective analysis

BACKGROUND

The restriction of hydroxyethylstarch (HES) necessitated changes in volume management in cardiac surgery, increasing the use of gelatin (GELA) and crystalloid (CRYS) mono strategies.

METHODS

This retrospective study evaluated the effects of changed volume replacement management to a GELA or CRYS mono therapy on mortality, acute kidney injury (AKI), blood loss, and transfusion in cardiac surgery patients with at least one coronary artery bypass grafting (CABG) at a university hospital. Three groups (HES n=938, GELA n=397, CRYS n=205) were derived from 1,540 patients with complete data sets. Data were analyzed by multiple regression models.

RESULTS

Patients had similar risk profiles, comorbidities, and preoperative routine diagnostics prior to surgery. No difference was observed in mortality and AKI. HES treated patients showed highest blood loss, followed by GELA while CRYS patients had the lowest (P<0.0001). Patients in the HES group had highest transfusion of packed red blood cells (PRBCs) and platelet concentrates (PCs), followed by GELA, whereas CRYS had the lowest (P<0.0001). Fresh frozen plasma (FFP) transfusion, administration of fibrinogen, and prothrombin complex concentrates (PCCs) were highest in HES group. CRYS showed the shortest time of mechanical ventilation (P<0.0001) and left the intensive care unit (ICU) significantly earlier (P<0.0001). Multivariable regression analysis found that colloid volume significantly predicted hospital mortality and renal replacement therapy (RRT), but not AKI.

CONCLUSIONS

Administration of crystalloids without any colloid showed no differences in mortality or AKI, but less blood loss and transfusion. Colloids should be considered critically and further studies should investigate effects of GELA in cardiac surgery.

A Multicenter, Open-Label, Randomized Controlled Trial of a Conservative Fluid Management Strategy Compared With Usual Care in Participants After Cardiac Surgery: The Fluids After Bypass Study

OBJECTIVES

There is little evidence to guide fluid administration to patients admitted to the ICU following cardiac surgery. This study aimed to determine if a protocolized strategy known to reduce fluid administration when compared with usual care reduced ICU length of stay following cardiac surgery.

DESIGN

Prospective, multicenter, parallel-group, randomized clinical trial.

SETTING

Five cardiac surgical centers in New Zealand conducted from November 2016 to December 2018 with final follow-up completed in July 2019.

PATIENTS

Seven-hundred fifteen patients undergoing cardiac surgery; 358 intervention and 357 usual care.

INTERVENTIONS

Randomization to protocol-guided strategy utilizing stroke volume variation to guide administration of bolus fluid or usual care fluid administration until desedation or up to 24 hours. Primary outcome was length of stay in ICU. Organ dysfunction, mortality, process of care measures, patient-reported quality of life, and disability-free survival were collected up to day 180.

MEASUREMENTS AND MAIN RESULTS

Overall 666 of 715 (93.1%) received at least one fluid bolus. Patients in the intervention group received less bolus fluid (median [interquartile range], 1,000 mL [250-2,000 mL] vs 1,500 mL [500-2,500 mL]; p < 0.0001) and had a lower overall fluid balance (median [interquartile range], 319 mL [-284 to 1,274 mL] vs 673 mL [38-1,641 mL]; p < 0.0001) in the intervention period. There was no difference in ICU length of stay between the two groups (27.9 hr [21.8-53.5 hr] vs 25.6 hr [21.9-64.6 hr]; p = 0.95). There were no differences seen in development of organ dysfunction, quality of life, or disability-free survival at any time points. Hospital mortality was higher in the intervention group (4% vs 1.4%; p = 0.04).

CONCLUSIONS

A protocol-guided strategy utilizing stroke volume variation to guide administration of bolus fluid when compared with usual care until desedation or up to 24 hours reduced the amount of fluid administered but did not reduce the length of stay in ICU.

Perioperative Clinical Trials in AKI

To characterize current evidence and current foci of perioperative clinical trials, we systematically reviewed Medline and identified perioperative trials involving 100 or more adult patients undergoing surgery and reporting renal end points that were published in high-impact journals since 2004. We categorized the 101 trials identified based on the nature of the intervention and summarized major trial findings from the five categories most applicable to perioperative management of patients. Trials that targeted ischemia suggested that increasing perioperative renal oxygen delivery with inotropes or blood transfusion does not reliably mitigate acute kidney injury (AKI), although goal-directed therapy with hemodynamic monitors appeared beneficial in some trials. Trials that have targeted inflammation or oxidative stress, including studies of nonsteroidal anti-inflammatory drugs, steroids, N-acetylcysteine, and sodium bicarbonate, have not shown renal benefits, and high-dose perioperative statin treatment increased AKI in some patient groups in two large trials. Balanced crystalloid intravenous fluids appear safer than saline, and crystalloids appear safer than colloids. Liberal compared with restrictive fluid administration reduced AKI in a recent large trial in open abdominal surgery. Remote ischemic preconditioning, although effective in several smaller trials, failed to reduce AKI in two larger trials. The translation of promising preclinical therapies to patients undergoing surgery remains poor, and most interventions that reduced perioperative AKI compared novel surgical management techniques or existing processes of care rather than novel pharmacologic interventions.

Starch or Saline After Cardiac Surgery: A Double-Blinded Randomized Controlled Trial

Background:

Despite decades of investigation, the balance of clinical risks and benefits of fluid supplementation with starch remain unresolved. Patient-centered outcomes have not been well explored in a “real-world” trial in cardiac surgery.

Objective:

We sought to compare a starch-based fluid strategy with a saline-based fluid strategy in the cardiac surgery patient.

Design:

A pragmatic blinded randomized controlled trial comparing starch-based with saline-based fluid strategy.

Setting:

A large tertiary academic center in London Ontario between September 2009 and February 2011.

Participants:

Patients undergoing planned, isolated coronary revascularization.

Measurements:

Serum creatinine and patient weight were measured daily postoperatively.

Methods:

Patients were randomized to receive 6% hydroxyethyl starch (Voluven) or saline for perioperative fluid requirements. Fluid administration was not protocolized. Co-primary outcomes were incidence of acute kidney injury (AKI) and maximum postoperative weight gain. Secondary outcomes included bleeding, transfusion, inotropic and ventilator support, and fluid utilization.

Results:

The study was prematurely terminated due to resource limitations. A total of 69 patients (19% female, mean age = 65) were randomized. Using RIFLE criteria for AKI, “risk” occurred in 12 patients in each group (risk ratio [RR] = 1.0; 95% confidence interval [CI] = 0.5-1.9; P = 1.00), whereas “injury” occurred in 7 of 35 (20%) and 3 of 34 (9%) of patients in the starch and saline groups, respectively (RR = 2.3; 95% CI = 0.6-8.1; P = .31). Maximum weight gain, bleeding and blood product usage, and overall fluid requirement were similar between groups.

Limitations:

The study had to be prematurely terminated due to resource limitations which led to a small sample size which was not sufficiently powered to detect a difference in the primary outcomes.

Conclusions:

This pragmatic double-blinded randomized controlled trial revealed a number of interesting hypothesis-generating trends and confirmed the feasibility of undertaking a logistically complex trial in a pragmatic fashion.

Hypertonic saline for fluid resuscitation after cardiac surgery (HERACLES): study protocol for a preliminary randomised controlled clinical trial

BACKGROUND

Intraoperative and postoperative management of cardiac surgery patients is complex, involving the application of differential vasopressors and volume therapy. It has been shown that a positive fluid balance has a major impact on postoperative outcome. Today, the advantages and disadvantages of buffered crystalloid solutes are a topic of controversy, with no consensus being reached so far. The use of hypertonic saline (HS) has shown promising results with respect to lower total fluid balance and postoperative weight gain in critically ill patients in preliminary studies. However, collection of more data on HS in critically ill patients seems warranted. This preliminary study aims to investigate whether fluid resuscitation using HS in patients following cardiac surgery results in less total fluid volume being administered.

METHODS

In a prospective double-blind randomised controlled clinical trial, we aim to recruit 96 patients undergoing elective cardiac surgery for ischaemic and/or valvular heart disease. After postoperative admission to the intensive care unit (ICU), patients will be randomly assigned to receive 5 ml/kg ideal body weight HS (7.3% NaCl) or normal saline (NS, 0.9% NaCl) infused within 60 min. Blood and urine samples will be collected preoperatively and postoperatively up to day 6 to assess changes in renal, cardiac, inflammatory, acid-base, and electrolyte parameters. Additionally, we will perform renal ultrasonography studies to assess renal blood flow before, during, and after infusion, and we will measure total body water using preoperative and postoperative body composition analysis (bioimpedance). Patients will be followed up for 90 days.

DISCUSSION

The key objective of this study is to assess the cumulative amount of fluid administered in the intervention (HS) group versus control (NS) group during the ICU stay. In this preliminary, prospective, randomised controlled clinical trial we will test the hypothesis that use of HS results in less total fluids infused and less postoperative weight gain when compared to the standard of intensive care in cardiac surgery patients.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03280745 . Registered on 12 September 2017.

Fluid management in patients undergoing cardiac surgery: effects of an acetate- versus lactate-buffered balanced infusion solution on hemodynamic stability (HEMACETAT)

BACKGROUND

Recent evidence suggests that acetate-buffered infusions result in better hemodynamic stabilization than 0.9% saline in patients undergoing major surgery. The choice of buffer in balanced crystalloid solutions may modify their hemodynamic effects. We therefore compared the inopressor requirements of Ringer's acetate and lactate for perioperative fluid management in patients undergoing cardiac surgery.

METHODS

Using a randomized controlled double-blind design, we compared Ringer's acetate (RA) to Ringer's lactate (RL) with respect to the average rate of inopressor administered until postoperative hemodynamic stabilization was achieved. Secondary outcomes were the cumulative dose of inopressors, the duration of inopressor administration, the total fluid volume administered, and the changes in acid-base homeostasis. Patients undergoing elective valvular cardiac surgery were included. Patients with severe cardiac, renal, or liver disease were excluded from the study.

RESULTS

Seventy-five patients were randomly allocated to the RA arm, 73 to the RL. The hemodynamic profiles were comparable between the groups. The groups did not differ with respect to the average rate of inopressors (RA 2.1 mcg/kg/h, IQR 0.5-8.1 vs. RL 1.7 mcg/kg/h, IQR 0.7-8.2, p = 0.989). Cumulative doses of inopressors and time on individual and combined inopressors did not differ between the groups. No differences were found in acid-base parameters and their evolution over time.

CONCLUSION

In this study, hemodynamic profiles of patients receiving Ringer's lactate and Ringer's acetate were comparable, and the evolution of acid-base parameters was similar. These study findings should be evaluated in larger, multi-center studies.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02895659 . Registered 16 September 2016.

Comparison of different techniques of central venous pressure measurement in mechanically ventilated critically ill patients

BACKGROUND

Several techniques exist for measuring central venous pressure (CVP) but little information is available about the accuracy of each method. The aim of this study was to compare different methods of CVP measurements in mechanically ventilated patients.

METHODS

CVP was measured in mechanically ventilated patients without spontaneous breathing using four different techniques: 1) end expiratory CVP measurement at the base of the" c" wave (CVP_MEASURED), chosen as the reference method; 2) CVP measurement from the monitor averaging CVP over the cardiac and respiratory cycles (CVP_MONITOR); 3) CVP measurement after a transient withdrawing of mechanical ventilation (CVP_NADIR); 4) CVP measurement corrected for the transmitted respiratory pressure induced by intrinsic PEEP (calculated CVP: CVP_CALCULATED). Bias, precision, limits of agreement, and proportions of outliers (difference > 2 mm Hg) were determined.

RESULTS

Among 61 included patients, 103 CVP assessments were performed. CVP_MONITOR bias [-0.87  (1.06) mm Hg] was significantly different from those of CVP_CALCULATED [1.42  (1.07), P < 0.001 and CVP_NADIR (1.04  (1.29), P < 0.001]. The limits of agreement of CVP_MONITOR [-2.96 to 1.21 mm Hg] were not significantly different to those of CVP_NADIR (-1.49 to 3.57 mm Hg, P = 0.39) and CVP_CALCULATED (-0.68 to 3.53 mm Hg, P = 0.31). The proportion of outliers was not significantly different between CVP_MONITOR (n = 5, 5%) and CVP_NADIR (n = 9, 9%, P = 0.27) but was greater with CVP_CALCULATED (n = 16, 15%, P = 0.01).

CONCLUSIONS

In mechanically ventilated patients, CVP_MONITOR is a reliable method for assessing CVP_MEASURED Taking into account transmitted respiratory pressures, CVP_CALCULATED had a higher proportion of outliers and precision than CVP_NADIR.

Evaluation of renal injury caused by acute volume replacement with hydroxyethyl starch 130/0.4 or Ringer's lactate solution in pigs

This work aimed to evaluate the effects on renal tissue integrity after hydroxyethyl starch (HES) 130/0.4 and Ringer's lactate (RL) administration in pigs under general anesthesia after acute bleeding. A total of 30 mL/kg of blood were passively removed from the femoral artery in two groups of Large White pigs, under total intravenous anesthesia with propofol and remifentanil. After bleeding, Group 1 (n = 11) received RL solution (25 mL/kg) and Group 2 (n = 11) received HES 130/0.4 solution (20 mL/kg). Additionally, Group 3 (n = 6) was not submitted to bleeding or volume replacement. Pigs were euthanized and kidneys were processed for histopathological and immunohistochemical analyses. Minimal to moderate glomerular, tubular, and interstitial changes, as well as papillary necrosis, were observed in all experimental groups. Pre-apoptosis and apoptosis indicators were higher in pigs that received HES 130/0.4, indicating a higher renal insult. Both HES 130/0.4 and RL administration may cause renal injury, although renal injury may be more significant in pigs receiving HES 13/0.4. Results also suggest that total intravenous anesthesia with propofol and remifentanil may cause renal injury, and this effect can be dose related.

Flow-directed vs. goal-directed strategy for management of hemodynamics

PURPOSE OF REVIEW

For the past 15 years, there has been a strong push to use goal-directed protocols for resuscitating critically ill patients and to manage perioperative patients. However, recent large clinical trials have failed to find evidence of improved outcome with this approach.

RECENT FINDINGS

A striking feature in the recent three large prospective randomized trials of septic patients and the one in high-risk perioperative patients is that outcomes in the control groups have markedly improved. This implies improvement in care and clinical acumen. Perhaps the clinical approach should be more toward further helping clinicians with their clinical choices. A good example is cardiac output. The objective of most hemodynamic interventions is to increase cardiac output. It would thus make sense to assess what happened to cardiac output after the intervention to determine if the intervention actually increased cardiac output. If it did not, another therapy should be chosen. I call this a flow-directed responsive protocol.

SUMMARY

A clinical approach that uses monitored values such as cardiac output as a feedback tool to evaluate the response to therapeutic interventions in individual patients may be better than protocols that set fixed targets for all study participants.

Crystalloid fluid choice in the critically ill : Current knowledge and critical appraisal

Intravenous infusion of crystalloid solutions is one of the most frequently administered medications worldwide. Available crystalloid infusion solutions have a variety of compositions and have a major impact on body systems; however, administration of crystalloid fluids currently follows a "one fluid for all" approach than a patient-centered fluid prescription. Normal saline is associated with hyperchloremic metabolic acidosis, increased rates of acute kidney injury, increased hemodynamic instability and potentially mortality. Regarding balanced infusates, evidence remains less clear since most studies compared normal saline to buffered infusion solutes.; however, buffered solutes are not homogeneous. The term "buffered solutes" only refers to the concept of acid-buffering in infusion fluids but this does not necessarily imply that the solutes have similar physiological impacts. The currently available data indicate that balanced infusates might have some advantages; however, evidence still is inconclusive. Taking the available evidence together, there is no single fluid that is superior for all patients and settings, because all currently available infusates have distinct differences, advantages and disadvantages; therefore, it seems inevitable to abandon the "one fluid for all" strategy towards a more differentiated and patient-centered approach to fluid therapy in the critically ill.

The dose of hydroxyethyl starch 6% 130/0.4 for fluid therapy and the incidence of acute kidney injury after cardiac surgery: A retrospective matched study

The safety of hydroxyethyl starches (HES) is still under debate. No studies have compared different dosing regimens of HES in cardiac surgery. We analyzed whether the incidence of Acute Kidney Injury (AKI) differed taking into account a weight-adjusted cumulative dose of HES 6% 130/0.4 for perioperative fluid therapy. This retrospective cohort study included all adult patients undergoing elective or emergency cardiac surgery with or without cardiopulmonary bypass. Exclusion criteria were patients on renal replacement therapy (RRT), cardiac trauma surgery, heart transplantation, patients with ventricular assist devices, subjects who required a surgical revision for bleeding and those whose medical records were incomplete. Primary endpoint was AKI following the creatinine based RIFLE classification. Secondary endpoints were 30-day mortality and RRT. Patients were divided into 2 groups whether they had received a cumulative HES dose of < 30 mL/kg (Low HES) or ≥ 30 mL/kg (High HES) during the intra- and postoperative period. A total of 1501 patients were analyzed with 983 patients in the Low HES and 518 subjects in the High HES group. 185 (18.8%) patients in the Low HES and 119 (23.0%) patients in the High HES group developed AKI (P = 0.06). In multivariable regression analysis the dose of HES administered per weight was not associated with AKI. After case-control matching 217 patients were analyzed in each group. AKI occurred in 39 (18.0%) patients in the Low HES and 50 (23.0%) patients in the High HES group (P = 0.19). In conditional regression analysis performed on the matched groups a lower weight-adjusted dose of HES was significantly associated with a reduced incidence of AKI [(Odds Ratio (95% CI) = 0.825 (0.727-0.936); P = 0.003]. In the absence of any safety study the cumulative dose of modern HES in cardiac surgery should be kept less than 30 mL/kg.

Intravenous Fluids in AKI: A Mechanistically Guided Approach

Acute kidney injury (AKI) has been associated with an increased risk of death and morbidity in many clinical scenarios. The prevention and treatment of AKI therefore has been advocated as a high-priority research focus. However, nearly all strategies tested in this setting have failed to prevent or cure AKI and fluid loading remains a cornerstone of preventive and curative treatment of AKI. Concerns have been raised, however, regarding both the efficacy and safety of fluid loading to prevent or reverse AKI. In this review, we address the question of the best use of fluid loading based on current preclinical and clinical data in a mechanistically guided approach. Impacts of fluid resuscitation on renal hemodynamics, from macrocirculation to microcirculation, with physiological end points as well as renal consequences of different fluids available are discussed. Finally, the complex relationship between renal hemodynamics is discussed.

Comparison of pulmonary artery catheter, echocardiography, and arterial waveform analysis monitoring in predicting the hemodynamic state during and after cardiac surgery

Objective:

The aim of this trial was to determine whether Flotrac Vigileo™ (FV™) provides a reliable representation of the hemodynamic state of a cardiac surgical patient population when compared to pulmonary artery catheter (PAC) and echocardiography in the peril-operative period.

Design:

This was a prospective observational trial comparing perioperative hemodynamic states using transesophageal echocardiography (TEE), transthoracic echocardiography (TTE), FV™ and PAC during and post cardiothoracic surgery.

Setting:

Tertiary regional hospital Intensive Care Unit (ICU).

Participants:

50 consecutive adult cardiothoracic patients with written consent provided.

Intervention:

Comparison of the perioperative hemodynamic states using echocardiography, FV™ and PAC was performed. Evaluation of the hemodynamic state (HDS) was performed using TEE, TTE, PAC and FV™ during and after cardiac surgery. Data were compared between the three hemodynamic assessment modalities.

Main Outcome Measure:

Predicted hemodynamic state.

Results:

FV™ and PAC were shown to correlate poorly with TEE/TTE assessment of the hemodynamic state. Both PAC and FV™ showed significant discordance with echocardiographic assessment of the hemodynamic state.

Conclusions:

In this trial, FV™ and PAC were shown to agree poorly with TTE/TEE assessment of the HDS in an adult cardiothoracic population. Agreement between the FV™ and PAC was also poor. Caution is recommended in interpreting isolated hemodynamic monitoring data. All hemodynamic monitoring devices have inherent sources of error. Caution is advised in interpreting any single device or measurement as a gold standard. We suggest that hemodynamic measuring devices such as FV™/PAC may act as triggers for a global hemodynamic assessment including consideration of TTE/TEE.

Sources of Heterogeneity in Trials Reporting Hydroxyethyl Starch 130/0.4 or 0.42 Associated Excess Mortality in Septic Patients: A Systematic Review and Meta-regression

Background:

This meta-analysis was to determine the association of the cumulative dose of 130/0.4 or 0.42 (hydroxyethyl starch [HES] 130/0.4*) or delta daily fluid balance (i.e., daily fluid balance in HES group over or below control group) with the heterogeneity of risk ratio (RR) for mortality in randomized control trials (RCTs).

Methods:

Three databases (PubMed, EMBASE, Cochrane) were searched to identify prospective RCTs reporting mortality in adult patients with sepsis to compare HES130/0.4* with crystalloids or albumin. Meta-analysis was performed using random effects. Sensitivity and meta-regression analyses were used to examine the heterogeneity sources of RR for mortality.

Results:

A total number of 4408 patients from 11 RCTs were included. The pooled RR showed no significant difference for overall mortality in patients with administration of HES130/0.4* compared with treatment of control fluids (RR: 1.02, 95% confidence interval: 0.90–1.17; P = 0.73). Heterogeneity was moderate across recruited trials (I² = 34%, P = 0.13). But, a significant variation was demonstrated in subgroup with crystalloids as control fluids (I²= 42%, P < 0.1). Sensitivity analysis revealed that trials with high risk of bias did not significantly impact the pooled estimates for mortality. Meta-regression analysis also did not determine a dose-effect relationship of HES130/0.4* with mortality (P = 0.298), but suggested daily delta fluid balance being likely associated with mortality in septic patients receiving HES130/130/0.4* (P = 0.079).

Conclusions:

Inappropriate daily positive fluid balance was likely an important source of heterogeneity in these trials reporting HES130/0.4* associated with excess mortality in septic patients.

Controversies in the use of hydroxyethyl starch solutions in small animal emergency and critical care

OBJECTIVES

To (1) review the development and medical applications of hydroxyethyl starch (HES) solutions with particular emphasis on its physiochemical properties; (2) critically appraise the available evidence in human and veterinary medicine, and (3) evaluate the potential risks and benefits associated with their use in critically ill small animals.

DATA SOURCES

Human and veterinary original research articles, scientific reviews, and textbook sources from 1950 to the present.

HUMAN DATA SYNTHESIS

HES solutions have been used extensively in people for over 30 years and ever since its introduction there has been a great deal of debate over its safety and efficacy. Recently, results of seminal trials and meta-analyses showing increased risks related to kidney dysfunction and mortality in septic and critically ill patients, have led to the restriction of HES use in these patient populations by European regulatory authorities. Although the initial ban on the use of HES in Europe has been eased, proof regarding the benefits and safety profile of HES in trauma and surgical patient populations has been requested by these same European regulatory authorities.

VETERINARY DATA SYNTHESIS

The veterinary literature is limited mostly to experimental studies and clinical investigations with small populations of patients with short-term end points and there is insufficient evidence to generate recommendations.

CONCLUSIONS

Currently, there are no consensus recommendations regarding the use of HES in veterinary medicine. Veterinarians and institutions affected by the HES restrictions have had to critically reassess the risks and benefits related to HES usage based on the available information and sometimes adapt their procedures and policies based on their reassessment. Meanwhile, large, prospective, randomized veterinary studies evaluating HES use are needed to achieve relevant levels of evidence to enable formulation of specific veterinary guidelines.

Pulse waveform hemodynamic monitoring devices: recent advances and the place in goal-directed therapy in cardiac surgical patients

Hemodynamic monitoring has evolved and improved greatly during the past decades as the medical approach has shifted from a static to a functional approach. The technological advances have led to innovating calibrated or not, but minimally invasive and noninvasive devices based on arterial pressure waveform (APW) analysis. This systematic clinical review outlines the physiologic rationale behind these recent technologies. We describe the strengths and the limitations of each method in terms of accuracy and precision of measuring the flow parameters (stroke volume, cardiac output) and dynamic parameters which predict the fluid responsiveness. We also analyzed the place of the APW monitoring devices in goal-directed therapy (GDT) protocols in cardiac surgical patients. According to the data from the three GDT-randomized control trials performed in cardiac surgery (using two types of APW techniques PiCCO and FloTrac/Vigileo), these devices did not demonstrate that they played a role in decreasing mortality, but only decreasing the ventilation time and the ICU and hospital length of stay.

Renal protection in cardiovascular surgery

Acute kidney injury (AKI) is one of the most relevant complications after major surgery and is a predictor of mortality. In Western countries, patients at risk of developing AKI are mainly those undergoing cardiovascular surgical procedures. In this category of patients, AKI depends on a multifactorial etiology, including low ejection fraction, use of contrast media, hemodynamic instability, cardiopulmonary bypass, and bleeding. Despite a growing body of literature, the treatment of renal failure remains mainly supportive (e.g. hemodynamic stability, fluid management, and avoidance of further damage); therefore, the management of patients at risk of AKI should aim at prevention of renal damage. Thus, the present narrative review analyzes the pathophysiology underlying AKI (specifically in high-risk patients), the preoperative risk factors that predispose to renal damage, early biomarkers related to AKI, and the strategies employed for perioperative renal protection. The most recent scientific evidence has been considered, and whenever conflicting data were encountered possible suggestions are provided.

Meta-analysis of colloids versus crystalloids in critically ill, trauma and surgical patients

Background

There is uncertainty regarding the safety of different volume replacement solutions. The aim of this study was systematically to review evidence of crystalloid versus colloid solutions, and to determine whether these results are influenced by trial design or clinical setting.

Methods

PubMed, Embase and the Cochrane Central Register of Controlled Trials were used to identify randomized clinical trials (RCTs) that compared crystalloids with colloids as volume replacement solutions in patients with traumatic injuries, those undergoing surgery and in critically ill patients. Adjusted odds ratios (ORs) for mortality and major morbidity including renal injury were pooled using fixed-effect and random-effects models.

Results

Some 59 RCTs involving 16 889 patients were included in the analysis. Forty-one studies (69 per cent) were found to have selection, detection or performance bias. Colloid administration did not lead to increased mortality (32 trials, 16 647 patients; OR 0·99, 95 per cent c.i. 0·92 to 1·06), but did increase the risk of developing acute kidney injury requiring renal replacement therapy (9 trials, 11 648 patients; OR 1·35, 1·17 to 1·57). Sensitivity analyses that excluded small and low-quality studies did not substantially alter these results. Subgroup analyses by type of colloid showed that increased mortality and renal replacement therapy were associated with use of pentastarch, and increased risk of renal injury and renal replacement therapy with use of tetrastarch. Subgroup analysis indicated that the risks of mortality and renal injury attributable to colloids were observed only in critically ill patients with sepsis.

Conclusion

Current general restrictions on the use of colloid solutions are not supported by evidence.

Postoperative Critical Care of the Adult Cardiac Surgical Patient. Part I: Routine Postoperative Care

OBJECTIVES

Cardiac surgery, including coronary artery bypass, cardiac valve, and aortic procedures, is among the most common surgical procedures performed in the United States. Successful outcomes after cardiac surgery depend on optimum postoperative critical care. The cardiac intensivist must have a comprehensive understanding of cardiopulmonary physiology and the sequelae of cardiopulmonary bypass. In this concise review, targeted at intensivists and surgeons, we discuss the routine management of the postoperative cardiac surgical patient.

DATA SOURCE AND SYNTHESIS

Narrative review of relevant English-language peer-reviewed medical literature.

CONCLUSIONS

Critical care of the cardiac surgical patient is a complex and dynamic endeavor. Adequate fluid resuscitation, appropriate inotropic support, attention to rewarming, and ventilator management are key components. Patient safety is enhanced by experienced personnel, a structured handover between the operating room and ICU teams, and appropriate transfusion strategies.

Principles of Fluid Management

Fluid therapy is the most common intervention received by acutely ill hospitalized patients; however, important questions on its optimal use remain. Its prescription should be patient and context specific, with clear indications and contradictions, and have the type, dose, and rate specified. Any fluid therapy, if provided inappropriately, can contribute unnecessary harm to patients. The quantitative toxicity of fluid therapy contributes to worse outcomes; this should prompt greater bedside attention to fluid prescription, fluid balance, development of avoidable complications attributable to fluid overload, and for the timely deresuscitation of patients whose clinical status and physiology allow active fluid mobilization.

Invasive hemodynamic monitoring

Although invasive hemodynamic monitoring requires considerable skill, studies have shown a striking lack of knowledge of the measurements obtained with the pulmonary artery catheter (PAC). This article reviews monitoring using a PAC. Issues addressed include basic physiology that determines cardiac output and blood pressure; methodology in the measurement of data obtained from a PAC; use of the PAC in making a diagnosis and for patient management, with emphasis on a responsive approach to management; and uses of the PAC that are not indications by themselves for placing the catheter, but can provide useful information when a PAC is in place.

Current tools for assessing heart function and perfusion adequacy

PURPOSE OF REVIEW

Many devices are currently available for measuring cardiac output and function. Understanding the utility of these devices requires an understanding of the determinants of cardiac output and cardiac function, and the use of these parameters in the management of critically ill patients. This review stresses the meaning of the physiological measures that are obtained with these devices and how these values can be used.

RECENT FINDINGS

Evaluation of devices for haemodynamic monitoring can include just measurement of cardiac output, the potential to track spontaneous changes in cardiac output or changes produced by volume infusions or vasoactive drugs, or the ability to assess cardiac function. Each of these puts different demands on the need for accuracy, precision, and reliability of the devices, and thus devices must be evaluated based on the clinical need.

SUMMARY

Evaluation of cardiac function is useful when first dealing with an unstable patient, but for ongoing management measurement of cardiac output itself is key and even more so the trend in relationship to the patient's overall condition. This evaluation would be greatly benefited by the addition of objective measures of tissue perfusion.

Fluid management in the cardiothoracic intensive care unit: diuresis--diuretics and hemofiltration

PURPOSE OF REVIEW

The present review discusses the current concepts of fluid management in cardiothoracic surgery, and its clinical implications with special reference to organ-related complications and their prevention.

RECENT FINDINGS

Current strategies in fluid management for cardiothoracic patients, various fluid formulation, and the preventive strategies for minimizing fluid-related complications are described, with particular reference to new discoveries and controversies that have arisen from recent literature.

SUMMARY

The optimal fluid management in cardiothoracic patients has not been settled. Results of recent clinical published trials highlight the need for minimizing fluid administration and attempting to use diuretics to achieve a negative fluid, although hypovolemia and hypoperfusion should be carefully considered. An individualized optimization of fluid status, using goal-directed therapy, has emerged as a possible preferable approach. The old debate between crystalloid and colloid solutions has been partially solved, as some colloids have demonstrated deleterious effect on renal function and coagulation system. Various preventive strategies have also emerged for minimizing fluid-related complications.

The impact of hydroxyethyl starches in cardiac surgery: a meta-analysis

Introduction

Recent studies in septic patients showed that adverse effects of hydroxyethyl starches (HESs) possibly outweigh their benefits in severely impaired physiological haemostasis. It remains unclear whether this also applies to patient populations that are less vulnerable. In this meta-analysis, we evaluated the impact of various HES generations on safety and efficacy endpoints in patients undergoing cardiac surgery.

Methods

We searched the PubMed, Embase and Cochrane Central Register of Controlled Trials databases for randomised controlled trials (RCTs) in the English or German language comparing the use of HES to any other colloid or crystalloid during open heart surgery.

Results

Blood loss and transfusion requirements were higher for older starches with mean molecular weights more than 200 kDa compared to other volume substitutes. In contrast, this effect was not observed with latest-generation tetrastarches (130/0.4), which performed even better when compared to albumin (blood loss of tetrastarch versus albumin: standardised mean difference (SMD), −0.34; 95% CI, −0.63, −0.05; P = 0.02; versus gelatin: SMD, −0.06; 95% CI, −0.20, 0.08; P = 0.39; versus crystalloids: SMD, −0.05; 95% CI, −0.20, 0.10; P = 0.54). Similar results were found for transfusion needs. Lengths of stay in the intensive care unit or hospital were significantly shorter with tetrastarches compared to gelatin (intensive care unit: SMD, −0.10; 95% CI, −0.15, −0.05; P = 0.0002) and crystalloids (hospital: SMD, −0.52; 95% CI, −0.90, −0.14; P = 0.007).

Conclusions

In this meta-analysis of RCTs, we could not identify safety issues with tetrastarches compared with other colloid or crystalloid solutions in terms of blood loss, transfusion requirements or hospital length of stay in patients undergoing cardiac surgery. The safety data on coagulation with older starches raise some issues that need to be addressed in future trials.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0656-0) contains supplementary material, which is available to authorized users.

Controversies in fluid therapy: Type, dose and toxicity

Fluid therapy is perhaps the most common intervention received by acutely ill hospitalized patients; however, a number of critical questions on the efficacy and safety of the type and dose remain. In this review, recent insights derived from randomized trials in terms of fluid type, dose and toxicity are discussed. We contend that the prescription of fluid therapy is context-specific and that any fluid can be harmful if administered inappropriately. When contrasting ‘‘crystalloid vs colloid’’, differences in efficacy are modest but differences in safety are significant. Differences in chloride load and strong ion difference across solutions appear to be clinically important. Phases of fluid therapy in acutely ill patients are recognized, including acute resuscitation, maintaining homeostasis, and recovery phases. Quantitative toxicity (fluid overload) is associated with adverse outcomes and can be mitigated when fluid therapy based on functional hemodynamic parameters that predict volume responsiveness and minimization of non-essential fluid. Qualitative toxicity (fluid type), in particular for iatrogenic acute kidney injury and metabolic acidosis, remain a concern for synthetic colloids and isotonic saline, respectively. Physiologically balanced crystalloids may be the ‘‘default’’ fluid for acutely ill patients and the role for colloids, in particular hydroxyethyl starch, is increasingly unclear. We contend the prescription of fluid therapy is analogous to the prescription of any drug used in critically ill patients.

Cardiac complications associated with goal-directed therapy in high-risk surgical patients: a meta-analysis

Patients with limited cardiopulmonary reserve are at risk of mortality and morbidity after major surgery. Augmentation of oxygen delivery index (DO2I) with i.v. fluids and inotropes (goal-directed therapy, GDT) has been shown to reduce postoperative mortality and morbidity in high-risk patients. Concerns regarding cardiac complications associated with fluid challenges and inotropes may prevent clinicians from performing GDT in patients who need it most. We hypothesized that GDT is not associated with an increased risk of cardiac complications in high-risk, non-cardiac surgical patients. We performed a systematic search of Medline, Embase, and CENTRAL databases for randomized controlled trials (RCTs) of GDT in high-risk surgical patients. Studies including cardiac surgery, trauma, and paediatric surgery were excluded. We reviewed the rates of all cardiac complications, arrhythmias, myocardial ischaemia, and acute pulmonary oedema. Meta-analyses were performed using RevMan software. Data are presented as odds ratios (ORs), [95% confidence intervals (CIs)], and P-values. Twenty-two RCTs including 2129 patients reported cardiac complications. GDT was associated with a reduction in total cardiovascular (CVS) complications [OR=0.54, (0.38-0.76), P=0.0005] and arrhythmias [OR=0.54, (0.35-0.85), P=0.007]. GDT was not associated with an increase in acute pulmonary oedema [OR=0.69, (0.43-1.10), P=0.12] or myocardial ischaemia [OR=0.70, (0.38-1.28), P=0.25]. Subgroup analysis revealed the benefit is most pronounced in patients receiving fluid and inotrope therapy to achieve a supranormal DO2I, with the use of minimally invasive cardiac output monitors. Treatment of high-risk surgical patients GDT is not associated with an increased risk of cardiac complications; GDT with fluids and inotropes to optimize DO2I during early GDT reduces postoperative CVS complications.

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.

Dose and type of crystalloid fluid therapy in adult hospitalized patients

OBJECTIVE

In this narrative review, an overview is given of the pros and cons of various crystalloid fluids used for infusion during initial resuscitation or maintenance phases in adult hospitalized patients. Special emphasis is given on dose, composition of fluids, presence of buffers (in balanced solutions) and electrolytes, according to recent literature. We also review the use of hypertonic solutions.

METHODS

We extracted relevant clinical literature in English specifically examining patient-oriented outcomes related to fluid volume and type.

RESULTS

A restrictive fluid therapy prevents complications seen with liberal, large-volume therapy, even though restrictive fluid loading with crystalloids may not demonstrate large hemodynamic effects in surgical or septic patients. Hypertonic solutions may serve the purpose of small volume resuscitation but carry the disadvantage of hypernatremia. Hypotonic solutions are contraindicated in (impending) cerebral edema, whereas hypertonic solutions are probably more helpful in ameliorating than in preventing this condition and improving outcome. Balanced solutions offer a better approach for plasma composition than unbalanced ones, and the evidence for benefits in patient morbidity and mortality is increasing, particularly by helping to prevent acute kidney injury.

CONCLUSIONS

Isotonic and hypertonic crystalloid fluids are the fluids of choice for resuscitation from hypovolemia and shock. The evidence that balanced solutions are superior to unbalanced ones is increasing. Hypertonic saline is effective in mannitol-refractory intracranial hypertension, whereas hypotonic solutions are contraindicated in this condition.

Hydroxyethyl starch for fluid resuscitation in critically ill patients

BACKGROUND

Intravenous fluid therapy is one of the most frequent interventions provided to patients in the intensive care unit; however, the type of fluid (i.e., crystalloid or colloid) used for resuscitation remains controversial. The most common type of colloid administered to resuscitate critically ill patients is hydroxyethyl starch (HES); however, its safety and efficacy have not been rigorously evaluated in large pragmatic randomized trials, and emerging data have accumulated to question its potential for toxic adverse effects.

OBJECTIVE

To evaluate the efficacy and safety of HES for fluid resuscitation in critically ill patients with a focus on survival and kidney function.

DESIGN

Multicentre (32 sites in Australia and New Zealand) blinded randomized controlled parallel-group trial.

METHODS

Seven thousand eligible adult patients (age - ≥ 18 yr) admitted to an intensive care unit and judged by their treating clinician to require fluid resuscitation were included in the study. Study treatment allocation used encrypted Web-based randomization stratified by site and an admission diagnosis of trauma.

INTERVENTION

Randomized patients were assigned to receive either 6% HES with a molecular weight of 130 kD and molar substitution ratio of 0.4 (130/0.4; Voluven(®), Fresenius Kabi) in 0.9% sodium chloride or 0.9% sodium chloride (saline) in indistinguishable Free flex 500 mL bags until intensive care unit (ICU) discharge, death, or 90 days after randomization. According to registration guidelines, the study fluid was administered to a maximum dose of 50 mL kg(-1) body weight per day and followed, if necessary, by open-label saline during the remaining 24-hr period.

MEASUREMENTS

The primary efficacy outcome was death within 90 days after randomization. The key secondary outcomes were incidence of acute kidney injury (AKI), defined by the RIFLE (Risk, Injury, Failure, Loss, Endstage) criteria; treatment with renal replacement therapy(RRT); development of new organ dysfunction, defined by the sequential organ failure assessment score; duration of mechanical ventilation; duration of RRT; cause-specific mortality; and adverse events. Tertiary outcomes were ICU and hospital lengths of stay and ICU and hospital mortality. The primary outcome was evaluated across six a prior idefined subgroups: urine output criteria for AKI; presence of sepsis; presence of trauma, with or without traumatic brain injury; acute physiology and chronic health evaluation (APACHE) score C ≥ 25; and receipt of HES prior to randomization.

MAIN RESULTS

The HES and saline groups had similar characteristics at baseline. The average age was 63 yr, 60.4% of patients were male, and 42.7% were admitted to the ICU after surgery (54.7% after elective surgery). The median [interquartile range] APACHE II score was 17[12.0-23.0] with a score C ≥ 25 in 18.2%. Sepsis and trauma were primary diagnoses in 28.8% and 7.9% of patients, respectively. Mechanical ventilation was received by 64.5% of patients, vasopressor therapy by 45.8%, and HES fluid prior to randomization by 15.1%. Enrolment occurred approximately 11 hr after ICU admission. During the first four days after randomization, the mean (standard deviation) study fluid received by the HES group was less when compared with the saline group [526 (425) mL day(-1) vs 616 (488) mL day(-1), respectively; P < 0.001]. Mortality at 90 days was 18.0% in patients receiving HES (597/3,315) and 17.0% in those receiving saline (566/3,336) (relative risk [RR] for HES, 1.06; 95% confidence interval (CI), 0.96 to 1.18; P = 0.26). There was no significant difference in 90-day mortality across the six a priori defined subgroups. Renal replacement therapy was received in 7.0% of patients in the HES group (235/3,352) and 5.8% of patients in the saline group (196/3,376) (RR for HES, 1.21; 95% CI, 1.00 to 1.45; P = 0.04). In the HES and saline groups, RIFLE - Injury occurred in 34.6% and 38.0% of patients,respectively (P = 0.005), and RIFLE - Failure occurred in 10.4% and 9.2% of patients, respectively (P = 0.12). There were no differences in mortality in ICU, in hospital, or at 28 days. Hydroxyethyl starch was associated with a decrease in new cardiovascular organ failure compared with saline (36.5% vs 39.9%, respectively; RR 0.91; 95% CI, 0.84 to 0.99; P = 0.03) and an increase in new hepatic organ failure compared with saline (1.9% vs 1.2%, respectively; RR 15.6; 95% CI, 1.03 to 2.36; P = 0.03). There were no differences between HES and saline for days in ICU or hospital or for duration of mechanical ventilation or RRT. Hydroxyethyl starch was associated with more adverse events compared with saline (5.3% vs 2.8%, respectively; RR 1.86; 95% CI, 1.46 to 2.38; P < 0.001). Adverse events were predominantly accounted for by pruritis and skin rash.

CONCLUSION

In critically ill patients receiving fluid resuscitation, there was no significant difference in 90-day mortality between 6% HES (130/0.4) or saline. Even so, more patients who received resuscitation with HES were treated with RRT and experienced adverse events.

Clinical review: Goal-directed therapy-what is the evidence in surgical patients? The effect on different risk groups

Patients with limited cardiac reserve are less likely to survive and develop more complications following major surgery. By augmenting oxygen delivery index (DO₂I) with a combination of intravenous fluids and inotropes (goal directed therapy (GDT)), postoperative mortality and morbidity of high-risk patients may be reduced. However, although most studies suggest that GDT may improve outcome in high-risk surgical patients, it is still not widely practiced. We set out to test the hypothesis that GDT results in greatest benefit in terms of mortality and morbidity in patients with the highest risk of mortality and have undertaken a systematic review of the current literature to see if this is correct. We performed a systematic search of Medline, Embase and CENTRAL databases for randomized controlled trials (RCTs) and reviews of GDT in surgical patients. To minimize heterogeneity we excluded studies involving cardiac, trauma, and paediatric surgery. Extremely high risk, high risk and intermediate risks of mortality were defined as >20%, 5 to 20% and <5% mortality rates in the control arms of the trials, respectively. Meta analyses were performed and Forest plots drawn using RevMan software. Data are presented as odd ratios (OR; 95% confidence intervals (CI), and P-values). A total of 32 RCTs including 2,808 patients were reviewed. All studies reported mortality. Five studies (including 300 patients) were excluded from assessment of complication rates as the number of patients with complications was not reported. The mortality benefit of GDT was confined to the extremely high-risk group (OR = 0.20, 95% CI 0.09 to 0.41; P < 0.0001). Complication rates were reduced in all subgroups (OR = 0.45, 95% CI 0.34 to 0.60; P < 0.00001). The morbidity benefit was greatest amongst patients in the extremely high-risk subgroup (OR = 0.27, 95% CI 0.15 to 0.51; P < 0.0001), followed by the intermediate risk subgroup (OR = 0.43, 95% CI 0.27 to 0.67; P = 0.0002), and the high-risk subgroup (OR 0.56, 95% CI 0.36 to 0.89; P = 0.01). Despite heterogeneity in trial quality and design, we found GDT to be beneficial in all high-risk patients undergoing major surgery. The mortality benefit of GDT was confined to the subgroup of patients at extremely high risk of death. The reduction of complication rates was seen across all subgroups of GDT patients.

Bench-to-bedside review: An approach to hemodynamic monitoring--Guyton at the bedside

Hemodynamic monitoring is used to identify deviations from hemodynamic goals and to assess responses to therapy. To accomplish these goals one must understand how the circulation is regulated. In this review I begin with an historical review of the work of Arthur Guyton and his conceptual understanding of the circulation and then present an approach by which Guyton's concepts can be applied at the bedside. Guyton argued that cardiac output and central venous pressure are determined by the interaction of two functions: cardiac function, which is determined by cardiac performance; and a return function, which is determined by the return of blood to the heart. This means that changes in cardiac output are dependent upon changes of one of these two functions or of both. I start with an approach based on the approximation that blood pressure is determined by the product of cardiac output and systemic vascular resistance and that cardiac output is determined by cardiac function and venous return. A fall in blood pressure with no change in or a rise in cardiac output indicates that a decrease in vascular resistance is the dominant factor. If the fall in blood pressure is due to a fall in cardiac output then the role of a change in the return function and cardiac function can be separated by the patterns of changes in central venous pressure and cardiac output. Measurement of cardiac output is a central component to this approach but until recently it was not easy to obtain and was estimated from surrogates. However, there are now a number of non-invasive devices that can give measures of cardiac output and permit the use of physiological principles to more rapidly appreciate the primary pathophysiology behind hemodynamic abnormalities and to provide directed therapy.