Infusion of hypertonic saline/starch during cardiopulmonary bypass reduces fluid overload and may impact cardiac function

NT-proBNP change is useful for predicting weaning failure from invasive mechanical ventilation among postsurgical patients: a retrospective, observational cohort study

BACKGROUND

To evaluate the predictive value of N-terminal prohormone B-type natriuretic peptide (NTproBNP) for weaning failure among patients undergoing major surgeries during spontaneous breathing trial (SBT), compared to traditional weaning parameters.

METHODS

The observational cohort study retrospectively included postsurgical patients who received IMV and underwent a 2 h SBT. According to weaning outcome, NTproBNP level at initiation (NTproBNP1) and at end of 2 h SBT(NTproBNP2), the ΔNTproBNP%, RSBI and MV were compared between weaning failure and weaning success group. Multiple logistical regression and ROC curve were used to evaluate the capability of NTproBNP to predict weaning failure.

RESULTS

Out of the 323 included postsurgical patients, 45 (13.9%) patients had failed weaning. The ΔNTproBNP% was a better predictor for weaning failure (AUC 0.744;95%CI,0.693-0.791) than NTproBNP1(AUC 0.639; 95%CI,0.580-0.694)), NTproBNP2(AUC 0.742, 95%CI,0.688-0.792) and other traditional weaning index such as RSBI (AUC 0.651; 95%CI, 0.597-0.703) and MV (AUC 0.552; 95%CI,0.496-0.607). The cutoff value of ΔNTproBNP% for predicting weaning failure was 23.3% with the sensitivity75.76% and specificity73.38%. The multiple logistic regression analysis found that ΔNTproBNP%>23.3% was an independent predictor of weaning failure.

CONCLUSION

ΔNTproBNP% may be a useful marker for predict weaning failure for postsurgical patients, and it's better to be more careful to withdraw from invasive mechanical ventilation for those postsurgical patients with ΔNTproBNP% >23.3%. The corresponding interventions to optimize cardiac function should be actively given to these patients.

Extracorporeal rewarming from experimental hypothermia: Effects of hydroxyethyl starch versus saline priming on fluid balance and blood flow distribution

NEW FINDINGS

What is the central question of this study? Mortality in accidental hypothermia patients rewarmed by extracorporeal circulation remains high. Knowledge concerning optimal fluid additions for extracorporeal rewarming is lacking, with no apparent consensus. Does colloid versus crystalloid priming have different effects on fluid balance and blood flow distribution during extracorporeal rewarming? What is the main finding and its importance? In our rat model of extracorporeal rewarming from hypothermic cardiac arrest, hydroxyethyl starch generates less tissue oedema and increases circulating blood volume and organ blood flow, compared with saline. The composition of fluid additions appears to be important during extracorporeal rewarming from hypothermia.

ABSTRACT

Rewarming by extracorporeal circulation (ECC) is the recommended treatment for accidental hypothermia patients with cardiac instability. Hypothermia, along with initiation of ECC, introduces major changes in fluid homeostasis and blood flow. Scientific data to recommend best practice use of ECC for rewarming these patients is lacking, and no current guidelines exist concerning the choice of priming fluid for the extracorporeal circuit. The primary aim of this study was to compare the effects of different fluid protocols on fluid balance and blood flow distribution during rewarming from deep hypothermic cardiac arrest. Sixteen anaesthetized rats were cooled to deep hypothermic cardiac arrest and rewarmed by ECC. During cooling, rats were equally randomized into two groups: an extracorporeal circuit primed with saline or primed with hydroxyethyl starch (HES). Calculations of plasma volume (PV), circulating blood volume (CBV), organ blood flow, total tissue water content, global O₂ delivery and consumption were made. During and after rewarming, the pump flow rate, mean arterial pressure, PV and CBV were significantly higher in HES-treated compared with saline-treated rats. After rewarming, the HES group had significantly increased global O₂ delivery and blood flow to the brain and kidneys compared with the saline group. Rats in the saline group demonstrated a significantly higher total tissue water content in the kidneys, skeletal muscle and lung. Compared with crystalloid priming, the use of an iso-oncotic colloid prime generates less tissue oedema and increases PV, CBV and organ blood flow during ECC rewarming. The composition of fluid additions appears to be an important factor during ECC rewarming from hypothermia.

Impact of maintenance, resuscitation and unintended fluid therapy on global fluid load after elective coronary artery bypass surgery

INTRODUCTION

Standardized protocols are provided for maintenance and replacement fluid therapy in critically ill patients. However, unintended fluid sources (analgesics, antibiotics and other drugs) are not always taken into account when prescribing intravenous fluid therapy. We evaluated the extent to which maintenance, resuscitation and unintended fluids contributed to total fluid load in elective coronary artery bypass graft patients during their ICU stay.

METHODS

Data on intravenous and oral fluid input and output were retrospectively collected from the electronic medical files.

RESULTS

Sixty patients were included. Maintenance fluids represented 1435 ± 570mL (49%) and 2214 ± 657mL (71%), resuscitation fluids 847 ± 542mL (29%) and 338 ± 559mL (11%), unintended fluids 639 ± 162mL (22%) and 576 ± 285mL (18%) respectively on day 1 and day 2. Mean oral intake increased almost fourfold (from 258mL to 1017mL) on the second day.

CONCLUSION

Postoperative maintenance and resuscitation fluids are responsible for most of the observed total fluid load on the first two days after elective coronary artery bypass graft surgery. Unintended fluid load is underestimated and has to be taken into account during fluid prescription.

Is the use of hydroxyethyl starch as priming solution during cardiac surgery advisable? A randomized, single-center trial

Introduction:

The use of cardiopulmonary bypass (CPB) leads to increased fluid filtration and edema. The use of artificial colloids to counteract fluid extravasation during cardiac surgery is controversial. Beneficial effects on global fluid loading, leading to better cardiac performance and hemodynamics, have been claimed. However, renal function and coagulation may be adversely affected, with unfavorable impact on outcome following cardiac surgery.

Methods:

Forty patients were randomly allocated to study groups receiving either acetated Ringer’s solution (CT group) or hydroxyethyl starch (HES group, Tetraspan®) as CPB priming solution. Fluid balance, bleeding and hemodynamics, including cardiac output, were followed postoperatively. The occurrence of acute kidney injury was closely registered.

Results:

Two patients were excluded from further analyzes due to surgical complications. Fluid accumulation was attenuated in the HES group (3374 (883) ml) compared with the CT group (4328 (1469) ml) (p=0.024). The reduced perioperative fluid accumulation was accompanied by an increased cardiac index immediately after surgery (2.7 (0.4) L/min/m2 in the HES group and 2.1 (0.3) L/min/m2 in the CT group (p<0.001)). No increase in bleeding could be demonstrated in the HES group. Three patients, all of them in the HES group, experienced acute kidney injury postoperatively.

Conclusions:

CPB priming with HES solution lowers fluid loading during bypass and improves cardiac function in the early postoperative period. The manifestation of acute kidney injury exclusively in the HES group of patients raises doubts about the use of HES products in conjunction with cardiac surgery. ( https://clinicaltrials.gov/ct2/show/NCT01511120 )

Hydroxyeyhyl starch: Controversies revisited

Hydroxyethyl starch (HES) family has been one of the cornerstones in fluid management for over four decades. Recent evidence from clinical studies and meta-analyses has raised few concerns about the safety of these fluids, especially in certain subpopulations of patients. High-quality clinical trials and meta-analyses have emphasized nephrotoxic effects, increased risk of bleeding, and a trend toward higher mortality in these patients after the use of HES solutions. Scientific evidence was derived from international guidelines, aggregated research literature, and opinion-based evidence was obtained from surveys and other activities (e.g., internet postings). On critical analysis of the current data available, it can be summarized that further large scale trials are still indicated before HES can be discarded.

Isoflurane in Contrast to Propofol Promotes Fluid Extravasation during Cardiopulmonary Bypass in Pigs

Background:

A highly positive intraoperative fluid balance should be prevented as it negatively impacts patient outcome. Analysis of volume-kinetics has identified an increase in interstitial fluid volume after crystalloid fluid loading during isoflurane anesthesia. Isoflurane has also been associated with postoperative hypoxemia and may be associated with an increase in alveolar epithelial permeability, edema formation, and hindered oxygen exchange. In this article, the authors compare fluid extravasation rates before and during cardiopulmonary bypass (CPB) with isoflurane- versus propofol-based anesthesia.

Methods:

Fourteen pigs underwent 2 h of tepid CPB with propofol (P-group; n = 7) or isoflurane anesthesia (I-group; n = 7). Fluid requirements, plasma volume, colloid osmotic pressures in plasma and interstitial fluid, hematocrit levels, and total tissue water content were recorded, and fluid extravasation rates calculated.

Results:

Fluid extravasation rates increased in the I-group from the pre-CPB level of 0.27 (0.13) to 0.92 (0.36) ml·kg−1·min−1, but remained essentially unchanged in the P-group with significant between-group differences during CPB (pb = 0.002). The results are supported by corresponding changes in interstitial colloid osmotic pressure and total tissue water content.

Conclusions:

During CPB, isoflurane, in contrast to propofol, significantly contributes to a general increase in fluid shifts from the intravascular to the interstitial space with edema formation and a possible negative impact on postoperative organ function.

Hydroxyethyl starch (HES) versus other fluid therapies: effects on kidney function

BACKGROUND

Hydroxyethyl starches (HES) are synthetic colloids commonly used for fluid resuscitation to replace intravascular volume, yet they have been increasingly associated with adverse effects on kidney function. This is an update of a Cochrane review first published in 2010.

OBJECTIVES

To examine the effects of HES on kidney function compared to other fluid resuscitation therapies in different patient populations.

SEARCH METHODS

We searched the Cochrane Renal Group's specialised register, the Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library), MEDLINE, EMBASE, MetaRegister and reference lists of articles. The most recent search was completed on November 19, 2012.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs in which HES was compared to an alternate fluid therapy for the prevention or treatment of effective intravascular volume depletion. Primary outcomes were renal replacement therapy (RRT), author-defined kidney failure and acute kidney injury (AKI) as defined by the RIFLE criteria.

DATA COLLECTION AND ANALYSIS

Screening, selection, data extraction and quality assessments for each retrieved article were carried out by two authors using standardised forms. All outcomes were analysed using relative risk (RR) and 95% confidence intervals (95% CI). Authors were contacted when published data were incomplete. Preplanned sensitivity and subgroup analyses were performed after data were analysed with a random-effects model.

MAIN RESULTS

This review included 42 studies (11,399 patients) including 19 studies from the original review (2010), as well as 23 new studies. Fifteen studies were excluded from the original review (nine retracted from publication due to concerns about integrity of data and six lacking individual patient creatinine data for the calculation of RIFLE criteria). Overall, there was a significant increase in the need for RRT in the HES treated individuals compared to individuals treated with other fluid therapies (RR 1.31, 95% CI 1.16 to 1.49; 19 studies, 9857 patients) and the number with author-defined kidney failure (RR 1.59, 95% CI 1.26 to 2.00; 15 studies, 1361 patients). The RR of AKI based on RIFLE-F (failure) criteria also showed an increased risk of AKI in individuals treated with HES products (RR 1.14, 95% CI 1.01 to 1.30; 15 studies, 8402 participants). The risk of meeting urine output and creatinine based RIFLE-R (risk) criteria for AKI was in contrast in favour of HES therapies (RR 0.95, 95% CI 0.91 to 0.99; 20 studies, 8769 patients). However, when RIFLE-R urine output based outcomes were excluded as per study protocol, the direction of AKI risk again favoured the other fluid type, with a non-significant RR of AKI in HES treated patients (RR 1.05, 95% CI 0.97 to 1.14; 8445 patients). A more robust effect was seen for the RIFLE-I (injury) outcome, with a RR of AKI of 1.22 (95% CI 1.08 to 1.37; 8338 patients). No differences between subgroups for the RRT and RIFLE-F based outcomes were seen between sepsis versus non-sepsis patients, high molecular weight (MW) and degree of substitution (DS) versus low MW and DS (≥ 200 kDa and > 0.4 DS versus 130 kDa and 0.4 DS) HES solutions, or high versus low dose treatments (i.e. ≥ 2 L versus < 2 L). There were differences identified between sepsis versus non-sepsis subgroups for the RIFLE-R and RIFLE-I based outcomes only, which may reflect the differing renal response to fluid resuscitation in pre-renal versus sepsis-associated AKI. Overall, methodological quality of the studies was good.

AUTHORS' CONCLUSIONS

The current evidence suggests that all HES products increase the risk in AKI and RRT in all patient populations and a safe volume of any HES solution has yet to be determined. In most clinical situations it is likely that these risks outweigh any benefits, and alternate volume replacement therapies should be used in place of HES products.

Hypertonic solution decreases extravascular lung water in cardiac patients undergoing cardiopulmonary bypass surgery

OBJECTIVE

To test the hypothesis that the infusion of hypertonic solution would decrease extravascular lung water postoperatively and thus improve pulmonary function.

DESIGN

Prospective, randomized, blinded trial.

SETTING

Tertiary cardiothoracic referral center.

PARTICIPANTS

Twenty-six patients with coronary artery disease who underwent surgery with cardiopulmonary bypass (CPB).

INTERVENTIONS

Patients were allocated randomly to receive 4 mL/kg of 7.2% NaCl/hydroxyethyl starch, 200/0.5 (HSH group) or an equal volume of 0.9% NaCl (control group) for 30 minutes starting after anesthesia induction. The extravascular lung water index, hemodynamic and biochemical data, and the rate of complications were analyzed.

MEASUREMENTS AND MAIN RESULTS

The extravascular lung water index was significantly lower (7 v 9.5 mL/kg) in the HSH group at the first postoperative day (p < 0.01). The index of arterial oxygenation efficiency was significantly higher at 5 minutes and 2 and 4 hours after cardiopulmonary bypass (CPB) in the HSH group (p < 0.05). The alveolar-arterial oxygen tension difference was significantly lower at 5 minutes and 2 and 4 hours after CPB in the HSH group (p < 0.01). The cardiac index was significantly higher at 5 minutes after infusion in the HSH group (p < 0.05).

CONCLUSIONS

The infusion of HSH leads to significant decreases in the extravascular lung water index during and after cardiac surgery and is associated with better preservation of pulmonary function and transient increases in the cardiac index. Further trials are needed to clarify the clinical advantages of hypertonic solution administration in patients undergoing surgery with CPB.

Capillary leakage in post-cardiac arrest survivors during therapeutic hypothermia - a prospective, randomised study

Background

Fluids are often given liberally after the return of spontaneous circulation. However, the optimal fluid regimen in survivors of cardiac arrest is unknown. Recent studies indicate an increased fluid requirement in post-cardiac arrest patients. During hypothermia, animal studies report extravasation in several organs, including the brain. We investigated two fluid strategies to determine whether the choice of fluid would influence fluid requirements, capillary leakage and oedema formation.

Methods

19 survivors with witnessed cardiac arrest of primary cardiac origin were allocated to either 7.2% hypertonic saline with 6% poly (O-2-hydroxyethyl) starch solution (HH) or standard fluid therapy (Ringer's Acetate and saline 9 mg/ml) (control). The patients were treated with the randomised fluid immediately after admission and continued for 24 hours of therapeutic hypothermia.

Results

During the first 24 hours, the HH patients required significantly less i.v. fluid than the control patients (4750 ml versus 8010 ml, p = 0.019) with comparable use of vasopressors. Systemic vascular resistance was significantly reduced from 0 to 24 hours (p = 0.014), with no difference between the groups. Colloid osmotic pressure (COP) in serum and interstitial fluid (p < 0.001 and p = 0.014 respectively) decreased as a function of time in both groups, with a more pronounced reduction in interstitial COP in the crystalloid group. Magnetic resonance imaging of the brain did not reveal vasogenic oedema.

Conclusions

Post-cardiac arrest patients have high fluid requirements during therapeutic hypothermia, probably due to increased extravasation. The use of HH reduced the fluid requirement significantly. However, the lack of brain oedema in both groups suggests no superior fluid regimen. Cardiac index was significantly improved in the group treated with crystalloids. Although we do not associate HH with the renal failures that developed, caution should be taken when using hypertonic starch solutions in these patients.

Trial registration

NCT00347477.