Intensive care unit management of the critically ill patient with fluid overload after open heart surgery

Safety and Feasibility of Regional Citrate Anticoagulation for Continuous Renal Replacement Therapy With Calcium-Containing Solutions: A Randomized Controlled Trial

BACKGROUND

Calcium-free (Ca-free) solutions are theoretically the most ideal for regional citrate anticoagulation (RCA) in continuous renal replacement therapy (CRRT). However, the majority of medical centers in China had to make a compromise of using commercially available calcium-containing (Ca-containing) solutions instead of Ca-free ones due to their scarcity. This study was designed to probe into the potential of Ca-containing solution as a secure and efficient substitution for Ca-free solutions.

METHODS

In this prospective, randomized single-center trial, 99 patients scheduled for CRRT were randomly assigned in a 1:1:1 ratio to one of three treatment groups: continuous veno-venous hemodialysis Ca-free dialysate (CVVHD Ca-free) group, continuous veno-venous hemodiafiltration calcium-free dialysate (CVVHDF Ca-free) group, and continuous veno-venous hemodiafiltration Ca-containing dialysate (CVVHDF Ca-containing) group at cardiac intensive care unit (CICU). The primary endpoint was the incidence of metabolic complications. The secondary endpoints included premature termination of treatment, thrombus of filter, and bubble trap after the process.

RESULTS

The incidence of citrate accumulation (18.2% vs. 12.1% vs. 21.2%) and metabolic alkalosis (12.1% vs. 0% vs. 9.1%) did not significantly differ among three groups (p > 0.05 for both). The incidence of premature termination was comparable among the groups (18.2% vs. 9.1% vs. 9.1%, p = 0.582). The thrombus level of the filter and bubble trap was similar in the three groups (p > 0.05 for all).

CONCLUSIONS

In RCA-CRRT for CICU population, RCA-CVVHDF with Ca-containing solutions and traditional RCA with Ca-free solutions had a comparable safety and feasibility.

TRIAL REGISTRATION

ChiCTR2100048238 in the Chinese Clinical Trial Registry.

Risk of fluid accumulation after cardiac surgery

Objective

Patients undergoing heart surgery are at high risk of postoperative fluid accumulation due to long procedures and cardiopulmonary bypass. In the present study, we sought to investigate the prevalence of postoperative fluid accumulation and its relation to adverse events in patients undergoing cardiac surgery.

Methods

CAREBANK is prospective, single-center cohort study focusing on the adverse events after cardiac surgery. The study population was divided into 2 groups based on 5% postoperative weight gain. All the in-hospital adverse events are registered on the database. The end points of the present study were length of hospital stay, length of intensive care unit stay, occurrence of new-onset atrial fibrillation after hospital major bleeding episodes major cardiac events, cerebrovascular events, and death. Three-month and 1-year follow-up data also include all major adverse events.

Results

Altogether 1001 adult cardiac surgery patients were enrolled. The most frequent operations were coronary artery bypass grafting (56.3%). Five hundred fifty-four out of 939 (59.0%) patients had ≥5% weight gain during index hospitalization. Patients with a weight gain ≥5% were more likely to be women, have lower body mass index, had heart failure, and more often had preoperative atrial fibrillation. In-hospital period fluid accumulation was associated with reoperation due bleeding and longer total hospital stay. At 3 months' follow-up, weight gain 5% or more was associated with increased occurrence of new-onset atrial fibrillation, this was not reflected in the occurrence of strokes, transient ischemic attacks, or myocardial infarctions.

Conclusions

Postoperative fluid excess is associated with adverse outcomes in cardiac surgery. Women, low-weight patients, and patients with cardiac failure or atrial fibrillation are prone to perioperative fluid accumulation.

Early Postoperative Volume Overload is a Predictor of 1-Year Post-Transplant Mortality in Pediatric Heart Transplant Recipients

Fluid restriction and diuretic management are mainstays in the postoperative management of cardiac patients, at risk of volume overload and its deleterious effects on primary cardiac function and multi-organ systems. The importance of fluid homeostasis is further emphasized among orthotopic heart transplant recipients (OHT). We sought to investigate the relationship between postoperative volume overload, mortality, and allograft dysfunction among pediatric OHT recipients within 1-year of transplantation. This is a retrospective cohort study from a single pediatric OHT center. Children under 21 years undergoing cardiac transplantation between 2010 and 2018 were included. Cumulative fluid overload (cFO) was assessed as percent fluid accumulation adjusted for preoperative body weight. Greater than 10% cFO defined those with postoperative cFO and a comparison of postoperative cFO vs. no postoperative cFO (< 5%) is reported. 102 pediatric OHT recipients were included. Early cFO at 72 h post-OHT occurred in 14% and overall cFO at 1-week post-OHT occurred in 23% of patients. Risk factors for cFO included younger age, lower weight, and postoperative ECMO. Early cFO was associated with postoperative mortality at 1-year, OR 8.6 (95% CI 1.4, 51.6), p = 0.04, independent of age and weight. There was no significant relationship between cFO and allograft dysfunction, measured by rates of clinical rejection and cardiopulmonary filling pressures within 1-year of transplant. Early postoperative volume overload is prevalent and associated with increased risk of death at 1-year among pediatric OHT recipients. It may be an important postoperative marker of transplant survival, and this relationship warrants further clinical investigation.

Fluid Overload in Pediatric Univentricular Patients Undergoing Fontan Completion

BACKGROUND

Fluid overload (FO) is known to occur frequently after pediatric cardiac surgery and is associated with morbidity and mortality. Fontan patients are at risk to develop FO due to their critical fluid balance. Furthermore, they need an adequate preload in order to maintain adequate cardiac output. This study aimed to identify FO in patients undergoing Fontan completion and the impact of FO on pediatric intensive care unit (PICU) length of stay (LOS) and cardiac events, defined as death, cardiac re-surgery or PICU re-hospitalization during follow-up.

METHODS

In this retrospective single center study, the presence of FO was assessed in 43 consecutive children undergoing Fontan completion.

RESULTS

Patients with more than 5% maximum FO had an extended PICU LOS (3.9 [2.9-6.9] vs. 1.9 [1.0-2.6] days; p < 0.001) and an increased length of mechanical ventilation (21 [9-121] vs. 6 [5-10] h; p = 0.001). Regression analysis demonstrated that an increase of 1% maximum FO was associated with a prolonged PICU LOS of 13% (95% CI 1.042-1.227; p = 0.004). Furthermore, patients with FO were at higher risk to develop cardiac events.

CONCLUSIONS

FO is associated with short-term and long-term complications. Further studies are needed to determine the impact of FO on the outcome in this specific population.

Fluid overload and mortality in critically ill patients with severe heart failure and cardiogenic shock-An observational cohort study

OBJECTIVE

Patients with heart failure (HF) and cardiogenic shock are especially prone to the negative effects of fluid overload (FO); however, fluid resuscitation in respective patients is sometimes necessary resulting in FO. We aimed to study the association of FO at ICU discharge with 30-day mortality in patients admitted to the ICU due to severe heart failure and/or cardiogenic shock.

METHODS

Retrospective, single-center cohort study. Patients with admission diagnoses of severe HF and/or cardiogenic shock were eligible. The following exclusion criteria were applied: (I) patients younger than 16 years, (II) patients admitted to our intermediate care unit, and (III) patients with incomplete data to determine FO at ICU discharge. We used a cumulative weight-adjusted definition of fluid balance and defined more than 5% as FO. The data were analyzed by univariate and adjusted univariate logistic regression.

RESULTS

We included 2,158 patients in our analysis. 185 patients (8.6%) were fluid overloaded at ICU discharge. The mean FO in the FO group was 7.2% [interquartile range (IQR) 5.8-10%]. In patients with FO at ICU discharge, 30-day mortality was 22.7% compared to 11.7% in non-FO patients (p < 0.001). In adjusted univariate logistic regression, we did not observe any association of FO at discharge with 30-day mortality [odds ratio (OR) 1.48; 95% confidence interval (CI) 0.81-2.71, p = 0.2]. No association between FO and 30-day mortality was found in the subgroups with HF only or cardiogenic shock (all p > 0.05). Baseline lactate (adjusted OR 1.27; 95% CI 1.13-1.42; p < 0.001) and cardiac surgery at admission (adjusted OR 1.94; 95% CI 1.0-3.76; p = 0.05) were the main associated factors with FO at ICU discharge.

CONCLUSION

In patients admitted to the ICU due to severe HF and/or cardiogenic shock, FO at ICU discharge seems not to be associated with 30-day mortality.

Copeptin: Prognostic Relevance as a Perioperative Marker in Pediatric Cardiac Surgery

BACKGROUND

Copeptin is a cleavage product of vasopressin. This study aimed to figure out if copeptin would be a suitable biomarker in patients with congenital heart disease in the postoperative course.

METHODS

The primary outcome endpoint of this study was the change in copeptin concentration perioperatively in patients with congenital heart disease after surgery, with the use of a cardiopulmonary bypass. Three blood samples were taken from 81 patients up to 6 years of age in order to evaluate changes in copeptin concentration.

RESULTS

Significant increase of copeptin concentration was shown between the first and second blood draws as well as between the first and third blood draws (Ps < .001). Additionally, positive and significant correlations (r ≥ .27) between the cardiopulmonary bypass times, The Society of Thoracic Surgeons and European Association for Cardio-Thoracic Surgery mortality category, the inotropic score, the duration of mechanical ventilation, the length of stay at the intensive care unit (ICU), the length of stay at the hospital, and the preoperative as well as the ICU copeptin levels were found.

CONCLUSIONS

Copeptin showed a tendency to predict the clinical outcome of patients after congenital heart surgery. Patients with higher copeptin levels underwent more complex procedures, had longer cardiopulmonary bypass times, required more catecholamine support, needed longer time of invasive ventilation, and had longer overall stay and ICU stay.

Altered kinetics of circulating progenitor cells in cardiopulmonary bypass (CPB) associated vasoplegic patients: A pilot study

Vasoplegia observed post cardiopulmonary bypass (CPB) is associated with substantial morbidity, multiple organ failure and mortality. Circulating counts of hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPC) are potential markers of neo-vascularization and vascular repair. However, the significance of changes in the circulating levels of these progenitors in perioperative CPB, and their association with post-CPB vasoplegia, are currently unexplored. We enumerated HSC and EPC counts, via flow cytometry, at different time-points during CPB in 19 individuals who underwent elective cardiac surgery. These 19 individuals were categorized into two groups based on severity of post-operative vasoplegia, a clinically insignificant vasoplegic Group 1 (G1) and a clinically significant vasoplegic Group 2 (G2). Differential changes in progenitor cell counts during different stages of surgery were compared across these two groups. Machine-learning classifiers (logistic regression and gradient boosting) were employed to determine if differential changes in progenitor counts could aid the classification of individuals into these groups. Enumerating progenitor cells revealed an early and significant increase in the circulating counts of CD34+ and CD34+CD133+ hematopoietic stem cells (HSC) in G1 individuals, while these counts were attenuated in G2 individuals. Additionally, EPCs (CD34+VEGFR2+) were lower in G2 individuals compared to G1. Gradient boosting outperformed logistic regression in assessing the vasoplegia grouping based on the fold change in circulating CD 34+ levels. Our findings indicate that a lack of early response of CD34+ cells and CD34+CD133+ HSCs might serve as an early marker for development of clinically significant vasoplegia after CPB.

Prescription of CRRT: a pathway to optimize therapy

Severe acute kidney injury (AKI), especially when caused or accompanied by sepsis, is associated with prolonged hospitalization, progression to chronic kidney disease (CKD), financial burden, and high mortality rate. Continuous renal replacement therapy (CRRT) is a predominant form of renal replacement therapy (RRT) in the intensive care unit (ICU) due to its accurate volume control, steady acid-base and electrolyte correction, and achievement of hemodynamic stability. This manuscript reviews the different aspects of CRRT prescription in critically ill patients with severe AKI, sepsis, and multiorgan failure in ICU. These include the choice of CRRT versus Intermittent and extended hemodialysis (HD), life of the filter/dialyzer including assessment of filtration fraction, anticoagulation including regional citrate anticoagulation (RCA), prescribed versus delivered CRRT dose, vascular access management, timing of initiation and termination of CRRT, and prescription in AKI/sepsis including adsorptive methods of removing endotoxins and cytokines.

Lower-Dose, Intravenous Chlorothiazide Is an Effective Adjunct Diuretic to Furosemide Following Pediatric Cardiac Surgery

OBJECTIVES

Postoperative fluid overload is ubiquitous in neonates and infants following operative intervention for congenital heart defects; ineffective diuresis is associated with poor outcomes. Diuresis with furosemide is widely used, yet there is often resistance at higher doses. In theory, furosemide resistance may be overcome with chlorothiazide; however, its efficacy is unclear, especially in lower doses and in this population. We hypothesized the addition of lower-dose, intravenous chlorothiazide following surgery in patients on high-dose furosemide would induce meaningful diuresis with minimal side effects.

METHODS

This was a retrospective, cohort study. Postoperative infants younger than 6 months, receiving high-dose furosemide, and given lower-dose chlorothiazide (1-2 mg/kg every 6-12 hours) were identified. Diuretic doses, urine output, fluid balance, vasoactive-inotropic scores, total fluid intake, and electrolyte levels were recorded.

RESULTS

There were 73 patients included. The addition of lower-dose chlorothiazide was associated with a significant increase in urine output (3.8 ± 0.18 vs 5.6 ± 0.27 mL/kg/hr, p < 0.001), more negative fluid balance (16.1 ± 4.2 vs -25.0 ± 6.3 mL/kg/day, p < 0.001), and marginal changes in electrolytes. Multivariate analysis was performed, demonstrating that increased urine output and more negative fluid balance were independently associated with addition of chlorothiazide. Subgroup analysis of 21 patients without a change in furosemide dose demonstrated the addition of chlorothiazide significantly increased urine output (p = 0.03) and reduced fluid balance (p < 0.01), further validating the adjunct effects of chlorothiazide.

CONCLUSION

Lower-dose, intravenous chlorothiazide is an effective adjunct treatment in postoperative neonates and infants younger than 6 months following cardiothoracic surgery.

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.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3420-6) contains supplementary material, which is available to authorized users.

Recruitment of sublingual microcirculation using handheld incident dark field imaging as a routine measurement tool during the postoperative de-escalation phase-a pilot study in post ICU cardiac surgery patients

Background

Management of tissue perfusion following cardiac surgery is a challenging task where common clinical parameters do not reflect microcirculatory dysfunction. Heterogeneity in blood flow perfusion and abnormalities in capillary density characterize microcirculatory dysfunction. The restoration of a normal microcirculation may become a novel target for therapy in the future in addition to macrocirculatory parameters. The aim of this study is to determine how the sublingual microcirculatory parameters vary at the bedside in post-cardiac surgery patients which underwent diuretic therapy to correct fluid overload.

Methods

In this prospective observational pilot study, video clips of sublingual microcirculation in post-cardiac surgery patients receiving furosemide and/or spironolactone to achieve normal fluid balance were recorded using Cytocam-IDF imaging. Data was obtained on the first (T0), second (T1), and third (T2) day after the patients left the intensive care unit (ICU). Measurements were analyzed off-line to obtain the following microcirculatory parameters: total vessel density (TVD), microcirculatory flow index (MFI), proportion of perfused vessel (PPV), and perfused vessel density (PVD). Macrocirculatory parameters and body weight were also collected at these time points.

Results

Ninety measurements were performed in ten post ICU cardiac surgery patients. Thirteen measurements were excluded due to quality reasons; these excluded measurements were spread across the patients and time points, and there was no loss of patients or time points. An increase in TVD was observed from T0 to T1 (20 ± 2.7 to 24 ± 3.2 mm/mm²; p = 0.0410) and from T0 to T2 (20 ± 2.7 to 26 ± 3.3 mm/mm²; p = 0.0005). An increase in PVD was present from T0 to T1 (19 ± 2.3 to 24 ± 3.5 mm/mm²; p = 0.0072) and from T0 to T2 (19 ± 2.3 to 26 ± 3.4 mm/mm², p = 0.0008). Fluid overload was assessed through a positive cumulative fluid balance on the day of ICU discharge.

Conclusions

Cytocam-IDF imaging to monitor microcirculation as a daily parameter is feasible and could become a valuable tool to non-invasively assess the tissue oxygenation at the bedside. An increase in TVD and PVD (functional capillary density) indicated the recruitment of the sublingual microcirculation in patients with diuretic therapy. Future research is needed to prove the correlation between the recruitment of the sublingual microcirculation and the de-escalation phase of the fluid management.

Efficacy and Safety of a Furosemide Continuous Infusion Following Cardiac Surgery

Objective:

To review the literature regarding the efficacy and safety of continuous intravenous infusion of loop diuretics following cardiac surgery.

Data Sources:

Articles were identified through a MEDLINE search (1966–March 2006) using the key words furosemide, bumetanide, torsemide, ethacrynic acid, loop diuretics, continuous infusions, intravenous infusions, surgery, cardiac surgery, cardiovascular surgery, and thoracic surgery. Search results were limited to studies in human subjects published in English. Additional references were identified through review of the bibliographies of the articles cited.

Study Selection and Data Extraction:

All clinical trials and observational reports identified that evaluated or described the efficacy and/or safety of a continuous infusion of a loop diuretic in adult or pediatric patients who had undergone cardiac surgery were included in this review.

Data Synthesis:

Loop diuretics are often used to promote diuresis following cardiac surgery. Studies in patients who have undergone cardiac surgery have demonstrated that a more consistent and sustained diuresis is produced by a continuous infusion of furosemide compared with intermittent bolus doses of furosemide. However, there does not appear to be a significant difference in total urine output or change in serum electrolyte levels when furosemide is administered as a continuous infusion compared with intermittent bolus doses.

Conclusions:

A continuous infusion of furosemide is an effective and safe method of diuresis in patients undergoing cardiac surgery.

Perioperative Circulating Blood Volume and Cardiac Function in Valve Disease

Circulating blood volume is important in managing fluid balance and cardiac function after surgery under cardiopulmonary bypass. Appropriate management differs among the valve disorders, but perioperative blood volume has not yet been considered. From February 2001 to March 2003, perioperative blood volume, fluid balance, cardiac index, and left ventricular stroke work index were measured in 31 patients: 10 with aortic stenosis, 9 with aortic regurgitation, 3 with mitral stenosis, and 9 with mitral regurgitation. All immediate postoperative blood volume measurements were less than preoperative values, and gradually returned to baseline. At all time points, blood volume in patients with aortic or mitral regurgitation was high, whereas it was low in those with stenosis, especially mitral stenosis. Fluid balance was positive in all patients. Postoperatively, there was a positive correlation between cardiac index and blood volume in all groups. The left ventricular stroke work index in the mitral regurgitation group was significantly higher than other groups, the aortic stenosis group was slightly lower, the mitral stenosis and mitral regurgitation groups were higher than the baseline, and the aortic regurgitation group was essentially unchanged. Thus, it is necessary to consider blood volume perioperatively in different valvular diseases to manage water balance.

Ultrasonographic caval indices do not significantly contribute to predicting fluid responsiveness immediately after coronary artery bypass grafting when compared to passive leg raising

Background

Appropriate fluid management is one of the most important elements of early goal-directed therapy after cardiothoracic surgery. Reliable determination of fluid responsivenss remains the fundamental issue in volume therapy.

The purpose of the study was to assess the usefulness of dynamic IVC-derived parameters (collapsibility index, distensibility index) in comparison to passive leg raising, in postoperative fluid management in mechanically ventilated patients with left ventricular ejection fraction ≥ 30 %, immediately after elective coronary artery bypass grafting.

Methods

Prospective observational case series study including 35 patients with LVEF ≥ 30 %, undergoingelective coronary artery bypass grafting was conducted. Transthoracic echocardiography, passive leg raising and intravenous administration of saline were performed in all study subjects. Dynamic parameters derived from ultrasonographic assessment of the IVC diameter (collapsibility index–CI and distensibility index–DI), cardiac output

Results

There were 24 (68.57 %) responders in the study population. There were no statistical differences between the groups in relation to: clinical parameters, pre- and postoperative LVEF, fluid balance and CVP. Change in cardiac output after passive leg raising correlated significantly with that after the volume expansion (p=0.000, r=0.822). Dynamic IVC derivatives were slightly higher in fluid responders, however this trend did not reach statistical significance. None of the caval indices correlated with fluid responsiveness.

Conclusion

Dynamic IVC-derived parameters do not predict fluid responsiveness in mechanically ventilated patients with preserved ejection fraction immediately after elective coronary artery bypass grafting. Passive leg raising is not inferior to volume expansion in differentiating between fluid responders and nonresponders. Immediate fluid challenge after CABG is safe and well tolerated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12947-016-0065-4) contains supplementary material, which is available to authorized users.

Fluid Overload Is Associated With Higher Mortality and Morbidity in Pediatric Patients Undergoing Cardiac Surgery

OBJECTIVES

Fluid overload after pediatric cardiac surgery is common and has been shown to increase both mortality and morbidity. This study explores the risk factors of early postoperative fluid overload and its relationship with adverse outcomes.

DESIGN

Secondary analysis of the prospectively collected data of children undergoing open-heart surgery between 2004 and 2008.

SETTING

Tertiary national cardiac center.

PATIENTS

One thousand five hundred twenty consecutive pediatric patients (<18 years old) were included in the analyses.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

In the first 72 hours of the postoperative period, the daily fluid balance was calculated as milliliter per kilogram and the daily fluid overload was calculated as fluid balance (L)/weight (kg) × 100. The primary endpoint was in-hospital mortality; the secondary outcomes were low cardiac output syndrome and prolonged mechanical ventilation. One thousand three hundred and sixty-seven patients (89.9%) had a cumulative fluid overload below 5%; 120 patients (7.8%), between 5% and 10%; and 33 patients (2.1%), above 10%. After multivariable analysis, higher fluid overload on the day of the surgery was independently associated with mortality (adjusted odds ratio, 1.14; 95% CI, 1.008-1.303; p = 0.041) and low cardiac output syndrome (adjusted odds ratio, 1.21; 95% CI, 1.12-1.30; p = 0.001). Higher maximum serum creatinine levels (adjusted odds ratio, 1.01; 95% CI, 1.003-1.021; p = 0.009), maximum vasoactive-inotropic scores (adjusted odds ratio, 1.01; 95% CI, 1.005-1.029; p = 0.042), and higher blood loss on the day of the surgery (adjusted odds ratio, 1.01; 95% CI, 1.004-1.025; p = 0.015) were associated with a higher risk of fluid overload that was greater than 5%.

CONCLUSIONS

Fluid overload in the early postoperative period was associated with higher mortality and morbidity. Risk factors for fluid overload include underlying kidney dysfunction, hemodynamic instability, and higher blood loss on the day of the surgery.

The impact of fluid balance on diagnosis, staging and prediction of mortality in critically ill patients with acute kidney injury

BACKGROUND

Fluid accumulation may delay recognition of acute kidney injury (AKI) in intensive care unit (ICU) patients. This study aims to evaluate the impact of fluid balance on the incidence, time of AKI diagnosis and predictive performance for outcomes of critically ill patients.

METHODS

This study included a cohort of 7696 adult ICU patients at Mayo Clinic Hospital in year 2011 with at least one serum creatinine (SCr) measured in ICU. AKI was defined based on SCr criterion for stage I of KDIGO definition. The AKI incidence and predictive performance for 60-day mortality was compared before and after SCr adjustment for fluid balance.

RESULTS

AKI was detected in 1860 (24.2 %) before and 1947 (25.3 %) after fluid balance adjustment (P < 0.001). Patients with AKI both before and after SCr adjustment had significantly higher 60-day mortality in comparison with patients who did not develop AKI (OR 3.38; 95 % CI 2.84-4.02). The risk of 60-day mortality in patients who met AKI criteria after but not before SCr adjustment was significantly higher than patients without AKI (OR 2.00; 95 % CI 1.25-3.11). In contrast, the risk of 60-day mortality in patients who met AKI criteria before but not after SCr adjustment was similar to patients without AKI (OR 1.19; 95 % CI 0.48-2.50). The C-statistic for unadjusted and adjusted SCr to predict 60-day mortality were 0.68 and 0.70, respectively (P = 0.001).

CONCLUSION

Our study found that SCr adjustment for fluid balance could result in a more accurate detection of AKI cases. We suggest using fluid balance adjustment for volume overload critically ill patients.

Acute Systemic Inflammation is Unlikely to Affect Adiponectin and Leptin Synthesis in Humans

Adipose tissue (AT), classically thought to be merely an energy store, has been shown to produce inflammatory and metabolically active cytokines. Recently, adiponectin and leptin, adipokines primarily synthesized by adipocytes, have attracted considerable attention because inflammation has been suggested to modulate adipokine levels. However, the regulation of adiponectin and leptin is complex and the knowledge about their synthesis within the early onset of inflammation is poorly understood. The aim of this study was to investigate if the synthesis of adiponectin and leptin is affected during the early phase of an acute systemic inflammation. Eighteen healthy subjects were allocated to vaccination against Salmonella typhi or to a control group, and adiponectin and leptin concentrations measured in plasma during 24 h. Nine patients, without markers of inflammation, undergoing open heart surgery were investigated before and after the operation by analysis of plasma levels and AT gene expression of adiponectin and leptin. Plasma interleukin (IL)-6 concentrations were measured in both cohorts. Plasma levels of IL-6 were doubled after vaccination and increased 30-fold after open heart surgery. Plasma levels of adiponectin and leptin were unchanged after vaccination whereas adiponectin and leptin tended to decrease after surgery. The gene expression of adiponectin and leptin was unaltered in omental and subcutaneous AT after surgery. Despite the use of two models of stimulated in vivo systemic inflammation, we found no evidence of an early regulation of adiponectin and leptin synthesis, indicating that these two adipokines are not key elements in an acute systemic inflammation in humans.

Bedside ultrasonographic measurement of the inferior vena cava fails to predict fluid responsiveness in the first 6 hours after cardiac surgery: a prospective case series observational study

OBJECTIVE

To assess validity of respiratory variation of inferior vena cava (IVC) diameter to predict fluid responsiveness and guide fluid therapy in mechanically ventilated patients during the first 6 hours after elective cardiac surgery.

DESIGN

Prospective observational case series study.

SETTING

Single-center hospital.

PATIENTS

50 consecutive patients undergoing elective cardiac surgery.

INTERVENTIONS

Transthoracic bedside echocardiography.

MEASUREMENTS AND MAIN RESULTS

Parameters derived from ultrasonographic assessment of the IVC diameter (collapsibility index [CI], distensibility index [DI], and IVC/aorta index). In the whole study group, change in fluid balance correlated with change in IVC maximum diameter (p = 0.034, r = 0.176). IVC-CI and IVC-DI correlated with IVC/aorta index. A weak correlation between central venous pressure (CVP) and IVC-derived parameters (IVC-CI and IVC-DI) was noticed. Despite statistical significance (p<0.05), all observed correlations expressed low statistical power (r<0.21). There were no statistically significant differences between fluid responders and nonresponders in relation to clinical parameters, CVP, ultrasound IVC measurement, and IVC-derived indices.

CONCLUSION

Dynamic IVC-derived parameters (IVC-CI, IVC-DI, and IVC/aorta index) and CVP are not reliable predictors of fluid responsiveness in the first 6 hours after cardiac surgery. Complexity of physiologic factors modulating cardiac performance in this group may be responsible for the difficulty in finding a plausible monitoring tool for fluid guidance. Bedside ultrasonographic measurement of IVC is unable to predict fluid responsiveness in the first 6 hours after cardiac surgery.

Clinical pharmacology of furosemide in neonates: a review

Furosemide is the diuretic most used in newborn infants. It blocks the Na⁺-K⁺-2Cl⁻ symporter in the thick ascending limb of the loop of Henle increasing urinary excretion of Na⁺ and Cl⁻. This article aimed to review the published data on the clinical pharmacology of furosemide in neonates to provide a critical, comprehensive, authoritative and, updated survey on the metabolism, pharmacokinetics, pharmacodynamics and side-effects of furosemide in neonates. The bibliographic search was performed using PubMed and EMBASE databases as search engines; January 2013 was the cutoff point. Furosemide half-life (t_1/2) is 6 to 20-fold longer, clearance (Cl) is 1.2 to 14-fold smaller and volume of distribution (Vd) is 1.3 to 6-fold larger than the adult values. t_1/2 shortens and Cl increases as the neonatal maturation proceeds. Continuous intravenous infusion of furosemide yields more controlled diuresis than the intermittent intravenous infusion. Furosemide may be administered by inhalation to infants with chronic lung disease to improve pulmonary mechanics. Furosemide stimulates prostaglandin E2 synthesis, a potent dilator of the patent ductus arteriosus, and the administration of furosemide to any preterm infants should be carefully weighed against the risk of precipitation of a symptomatic patent ductus arteriosus. Infants with low birthweight treated with chronic furosemide are at risk for the development of intra-renal calcifications.

Acute kidney injury after cardiac surgery according to Risk/Injury/Failure/Loss/End-stage, Acute Kidney Injury Network, and Kidney Disease: Improving Global Outcomes classifications

PURPOSE

The epidemiology of acute kidney injury (AKI) after cardiac surgery depends on the definition used. Our aims were to evaluate the Risk/Injury/Failure/Loss/End-stage (RIFLE) criteria, the AKI Network (AKIN) classification, and the Kidney Disease: Improving Global Outcomes (KDIGO) classification for AKI post-cardiac surgery and to compare the outcome of patients on renal replacement therapy (RRT) with historical data.

METHODS

Retrospective analysis of 1881 adults who had cardiac surgery between May 2006 and April 2008 and determination of the maximum AKI stage according to the AKIN, RIFLE, and KDIGO classifications.

RESULTS

The incidence of AKI using the AKIN and RIFLE criteria was 25.9% and 24.9%, respectively, but individual patients were classified differently. The area under the receiver operating characteristic curve for hospital mortality was significantly higher using the AKIN compared with the RIFLE criteria (0.86 vs 0.78, P = .0009). Incidence and outcome of AKI according to the AKIN and KDIGO classification were identical. The percentage of patients who received RRT was 6.2% compared with 2.7% in 1989 to 1990. The associated hospital mortality fell from 82.9% in 1989 to 1990 to 15.6% in 2006 to 2008.

CONCLUSIONS

The AKIN classification correlated better with mortality than did the RIFLE criteria. Mortality of patients needing RRT after cardiac surgery has improved significantly during the last 20 years.

Use of peripheral ultrafiltration in the postoperative cardiac surgery patient

BACKGROUND

: After cardiac surgery, most patients have development of third-space fluid retention, commonly treated with diuretics. In some patients diuretics are ineffective. In this subset, a simplified system for ultrafiltration was used for fluid extraction.

METHODS

: After obtaining permission from the institutional review board, the hospital charts of the first 30 patients having ultrafiltration were retrospectively reviewed to abstract data on fluid extraction and patient outcomes. Data are expressed as mean ± standard deviation.

RESULTS

: From April 2004 through January 2006, 30 patients were selected for ultrafiltration. In one patient, adequate intravenous access could not be obtained. There were 11 female and 18 male (age, 69 ± 12 years) postoperative cardiac surgery patients. The mean ultrafiltration run was 10.5 ± 9 hours, resulting in fluid extraction of 3528 ± 2111 mL per run and 5596 ± 3870 mL per patient (11 patients had more than 1 run). Hospital stay was 9.4 ± 4.4 days. Three patients died unrelated to ultrafiltration.

CONCLUSIONS

: Ultrafiltration as an alternative means of fluid extraction in postoperative cardiac surgery patients was effective and well tolerated.

Draining Fluids through a Peritoneal Catheter in Newborns after Cardiac Surgery Helps to Control Fluid Balance

Fluid overload, a common complication following cardiac surgery in infants is often difficult to manage. Dialysis can be used in severe cases, but may not be well tolerated. In such patients, peritoneal drainage could be an alternative option for fluid removal. We report the case of a newborn with a truncus arteriosus who developed postoperatively a complicated clinical course with right ventricular dysfunction, prerenal condition as well as fluid overload despite diuretic therapy. Dialysis was indicated for fluid removal. Peritoneal dialysis was started using a surgically placed Tenckhoff catheter and stopped due to inefficacy and leaks and no other modalities of dialysis were used. However, the catheter was left in place over a period of two months for fluid drainage and removed because of unexplained fever. In order to determine the effect of peritoneal drainage, we selected a period of one week before and one week after the removal of the drain to compare daily clinical data, urine electrolytes and renal function and found a positive effect on fluid balance control. We conclude that the fluid removal by continuous peritoneal drainage is a simple and safe alternative that can be used to control fluid balance in infants after cardiac surgery.

Perioperative fluid management in renal transplantation: a narrative review of the literature

Adequate volume maintenance is essential to prevent acute renal failure during major surgery or to ensure graft function after renal transplantation. The various recommendations on the optimum fluid therapy are based, at best, on sparse evidence only from observational studies. This article reviews the literature on perioperative fluid management in renal transplantation. Crystalloid solutions not exerting any specific side-effects are the first choice for volume replacement in kidney transplantation. The use of colloids should be restricted to patients with severe intravascular volume deficits necessitating high volume restoration. The routine application of albumin, dopamine, and high dose diuretics is no longer warranted. Mannitol given immediately before removal of the vessel clamps reduces the requirement of post-transplant dialysis, but has no effects on graft function in the long term. There is insufficient evidence on the best use of dialysis, but it seems peritoneal dialysis pretransplant is associated with less delayed graft function, whereas the preference of dialysis post-transplant is not yet well-founded. This review article should provide better guidance for fluid management in kidney transplantation until best-evidence guidelines can be established based upon more research.

Evaluating the reliability of recorded fluid balance to approximate body weight change in patients undergoing cardiac surgery

OBJECTIVES

The objective of this study was to investigate body weight change in adult patients undergoing cardiac surgery and to assess the accuracy of conventional recorded fluid balance charting methods to reflect this change in body weight.

DESIGN

This was a descriptive study.

SETTING

This study was conducted at the cardiac care unit and medical-surgical intensive care unit (ICU) of a private hospital in Melbourne, Australia.

SUBJECTS

The subjects were 32 adult patients who underwent cardiac surgical procedures. Twenty-six were male, and the mean age was 67 years (range 36-84 years). Twenty-three patients underwent coronary artery bypass graft surgery, and nine patients underwent heart valve repair or replacement+/-coronary artery bypass graft surgery between December 2003 and May 2004.

OUTCOME MEASURES

The measures were recorded fluid balance for the perioperative period together with body weight measurements from the night before surgery and immediately on discharge from the ICU. An additional body weight measurement on the seventh postoperative day provided a trajectory of body weight gain or loss for the period of hospitalization after surgery. A retrospective medical history audit and an HV-CS digital chair scale (A&D Mercury Pty Ltd, Victoria, Australia) were used to collect the data.

RESULTS

Analysis revealed that 30 patients increased their body weight from the night before surgery until discharge from the ICU. The mean weight gain was 3.34 kg (standard deviation [SD] 1.17, 95% confidence interval 2.70-3.98, P<.001). The average preoperative body weight was 80.97 kg (SD 16.79), whereas the average ICU postoperative weight was 83.94 kg (SD 16.15). Twenty-six patients (81.25%) had returned to, or were below, their preoperative weight by their seventh postoperative day (M 2.96 kg, SD 2.24 kg, P<.05). The average recorded fluid balance during the perioperative period was +1.56 L (SD 2.59 L, P<.001) with a difference of 1.39 kg between the recorded fluid balance and measured body weight change. Three patients (9.75%) met the criteria for accurate recorded fluid balance, and eight patients (25%) experienced a net difference in the opposite direction between recorded fluid balance and body weight change during the perioperative period.

CONCLUSION

Body weight in patients who undergo cardiac surgery was found to fluctuate over the perioperative period. Use of recorded fluid balance to reflect change in body weight for patients undergoing cardiac surgery was deemed unreliable. Further investigation of body weight change and scrutiny of conventional recorded fluid balance charting methods for patients who undergo cardiac surgery is needed.

Reviews: The Current State of Nonuremic Applications for Extracorporeal Blood Purification

Despite the commonly accepted indications for hemodialysis and extracorporeal depuritive techniques, some clinicians have come to rely on blood purification for clinical states where the targeted substance for removal differs from uremic waste products. Over the last decade, a number of studies have emerged to help define the application of extracorporeal blood purification (ECBP) to these "nonuremic" indications. This review describes the application of extracorporeal blood purification in clinical states including sepsis, rhabdomyolysis, congestive heart failure, hepatic failure, tumor lysis syndrome, adult respiratory distress syndrome, intravenous contrast exposure, and lactic acidosis. Additional comments are provided to review existing literature on thermoregulation and osmoregulation, including acute brain injury.

On-pump versus off-pump coronary artery bypass grafting: impact on postoperative renal failure requiring renal replacement therapy

BACKGROUND

Despite refinements in perioperative patient management postoperative renal failure requiring hemofiltration or dialysis is still a common complication after coronary artery bypass grafting associated with impaired patient outcome.

METHODS

Prospective data on 9,631 patients receiving myocardial revascularization with (coronary artery bypass grafting [n = 8,870]) or without cardiopulmonary bypass (off-pump coronary artery bypass grafting [n = 761]) between April 1996 and August 2001 were evaluated by univariate and multivariate logistic regression analysis.

RESULTS

Overall prevalence of postoperative continuous renal replacement therapy was 4.1% (coronary artery bypass grafting, 4.3%; off-pump coronary artery bypass grafting, 1.8%; p = 0.001). Thirty of 40 selected preoperative and intraoperative patient and treatment related variables had a high association with the requirement for postoperative renal replacement therapy; fifteen of these variables were independent predictors in the whole study population. Off-pump coronary artery bypass surgery was identified as having a significantly lower predictive value for postoperative continuous renal placement therapy. In the subgroup of patients undergoing off-pump coronary artery bypass grafting surgery, a second multivariate logistic regression model revealed preoperative cardiogenic shock, urgent operation, intraoperative low cardiac output, and high transfusion requirement as independent predictors for postoperative renal replacement therapy.

CONCLUSIONS

Patients with preoperative nondialysis dependent renal insufficiency are at a high risk for further decline in renal function requiring postoperative continuous renal replacement therapy. Off-pump coronary artery bypass surgery is associated with a lower prevalence of postoperative renal replacement therapy after coronary artery bypass grafting.

Blood purification in non-renal critical illness

Extracorporeal therapies designed to remove substances from the circulation now include hemodialysis, hemofiltration, hemoadsorption, plasma filtration, cell-based therapies and combinations of any of the above. In recent years, there have been considerable advances in our understanding and technical capabilities, but consensus over the optimal way, and under what conditions to use these therapies does not exist. Consequently, we have initiated a series of conferences under the auspices of the Acute Dialysis Quality Initiative (ADQI). ADQI aims at establishing an evidence-based appraisal and set of consensus recommendations to standardize care and direct further research. The results of previous consensus conferences are available on-line at www.ADQI.net. ADQI conferences have focused on research and management of renal disease. However, extracorporeal therapies are being used or investigated in the management of many other disease processes including systemic inflammation, liver disease, cardiac disease and thrombotic diseases.

Nonpharmacologic care of heart failure: counseling, dietary restriction, rehabilitation, treatment of sleep apnea, and ultrafiltration

The prognosis of patients with chronic congestive heart failure (CHF) depends not only on pharmacologic therapy but also on nonpharmacologic aspects. A complete and ongoing education program for treating CHF includes an understanding of the causes of CHF, symptoms, diet, salt and fluid restriction, drug regimen, compliance, physical and work activities, lifestyle changes, and measures of self-control. Moreover, the nonpharmacologic treatment (dietary modifications, lifestyle, physical exercise, and health care education) must be inserted in a multidisciplinary program organized by the physician in conjunction with the health system, the nurses, and, especially, the patients themselves, who must understand their disease and the many therapeutic options. Cardiologists should treat patients in a clear and comprehensible way, and other specialists (dietitians, physiotherapists, psychologists, nurses, and social workers), together with the patient's family, should strive for the best living conditions for the patient. In this way, the treatment of CHF can improve the quantity and quality of life and save a significant amount in health care costs.

Acute renal failure and multiple organ dysfunction in the ICU: from renal replacement therapy (RRT) to multiple organ support therapy (MOST)

Renal replacement therapy (RRT) has evolved from the concept that we need to treat the dysfunction of a single organ (the kidney). As intensive care units have become more and more complex, it has become clear that the majority of patients with acute renal failure often have dysfunction of several other organs. In order to facilitate single organ support in this setting, continuous renal replacement therapy (CRRT) techniques have been developed. However, CRRT has opened the door to the concept that targeting renal support as the only goal of extracorporeal blood purification may be a simplistic view of our therapeutic aims. In this article we argue that it is now time to move from the simple goal of achieving adequate renal support. The proper goal of extracorporeal blood purification in ICU should be multi-organ support therapy (MOST). We explain why MOST represents the most logical future conceptual and practical evolution of CRRT and illustrates the biological rationale, supplying animal and clinical evidence that confirms the need to move rapidly in this direction theoretically, practically and technologically.

Techniques for assessing and achieving fluid balance in acute renal failure

Fluid therapy, together with attention to oxygen supply, is the cornerstone of resuscitation in all critically ill patients. Hypovolemia results in inadequate blood flow to meet the metabolic requirements of the tissues and must be treated urgently to avoid the complication of progressive organ failure, including acute renal failure. The kidney plays a critical role in body fluid homeostasis. Renal dysfunction disturbs this homeostasis and requires special attention to issues of fluid balance and fluid overload. In addition, fluid therapy is the only treatment that has been shown to be effective in the prevention of acute renal failure. Special attention to volume status is therefore required in patients at risk for acute renal failure. Hypovolemia is also a major causal factor of morbidity during hemodialysis and may contribute to further renal insults. Although the importance of fluid management is generally recognized, the choice of fluid, the amount, and assessment of fluid status are controversial. As the choice of fluids becomes wider and monitoring devices become more sophisticated, the controversy increases. This article provides an overview of the concept of fluid management in the critically ill patient with acute renal failure.

Protect the heart in the intensive care unit--but how?

The heart plays a pivotal role in determining the oxygen supply to the body. As a result of its high oxygen extraction ratio, the myocardium must function efficiently to supply itself with oxygen. In the context of the ICU, the efficient functioning of the myocardium is confounded by a number of pathologic processes that may interfere with its oxygen supply or increase its oxygen demand. Conventional drug treatment of acute myocardial decompensation tends to increase myocardial oxygen demand. The myocardium may potentially be "protected" by treatment modalities that favorably alter the oxygen supply to demand ratio. Newer methods of protecting the heart may involve improving the coordination of myocardial contraction, using novel inotropic agents, supporting the myocardium metabolically, administrating blood products more conservatively, favorably altering the immune response, and using mechanical support devices. Myocardial protection may be improved by better use and understanding of monitors of myocardial performance.

Continuous renal replacement therapy: opinions and evidence

Continuous arteriovenous haemofiltration (CAVH) is the first example of continuous renal replacement therapy (CRRT). CAVH was first applied for the treatment of diuretic unresponsive fluid overload. Subsequently, CRRT has undergone a remarkable growth, and it is now performed with pump technology (CVVH) and via double-lumen central venous catheters. In many intensive care units, especially in Australia and in Europe, CRRT has become the dominant, if not exclusive, form of artificial renal support. Continuous haemofiltration is now used beyond the original indications of blood purification, for the treatment of certain drug intoxications, for severe cardiac failure, for volume control during, after cardiopulmonary bypass, and to decrease the toxicity of chemotherapy. Furthermore, there is strong ongoing research into its role or that of derived techniques as possible adjuvant therapies during severe sepsis. Despite its large use, the current state of CRRT is surrounded by some controversies, and an effort should be made to give a dispassionate distillation of the literature for a final common definition of what is based on opinions and what carries sufficient evidence.

Clinical benefit and approach of ultrafiltration in acute heart failure

Because of the increasing incidence of acute heart failure admissions to critical care units, nephrologists have been asked to become more involved in the management of these patients. Renal dysfunction is a major element in impeding clinical recovery. In acute heart failure, renal function is often abnormal. The judicious application of ultrafiltration techniques may represent an efficacious adjunct to present conventional practice. In patients with refractory congestive heart failure, the ability to provide continuous, daily, large volume removal not only improves volume status but also the clinical symptoms of the decompensated patient. A thorough literature review supports the premise that starting hemofiltration is an appropriate alternative for difficult and unstable cardiac patients. An optimal strategy utilizing continuous renal replacement therapy can dramatically improve the patient's clinical condition, mitigate the neurohumoral stimulation, increase urinary output and promote absorption of excessive extravascular fluid.