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

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.

Non-surgical Risk Factors for the Development of Chylothorax in Children after Cardiac Surgery-Does Fluid Matter?

We hypothesize that there are post-operative, non-surgical risk factors that could be modified to prevent the occurrence of chylothorax, and we seek to determine those factors. Retrospective chart review of 285 consecutive patients < 18 years who underwent cardiac surgery from 2015 to 2017 at a single institution pediatric intensive care unit. Data was collected on patient demographics, cardiac lesion, surgical and post-operative characteristics. Primary outcome was development of chylothorax. Of 285 patients, median age was 189 days, median weight was 6.6 kg, 48% were female, and 10% had trisomy 21. 3.5% of patients developed upper extremity DVTs, and 8% developed chylothorax. At 24 h following surgery, a majority were in the 0-10% fluid overload category or had a negative fluid balance (63% and 34%, respectively), and a positive fluid balance was rare at 72 h (16%). In univariate analysis, age, weight, bypass time, DVT, arrhythmia, and trisomy 21 were significantly associated with chylothorax and adjusted for in logistic regression. Presence of an upper extremity DVT (OR 49.8, p < 0.001) and trisomy 21 (OR 5.8, p < 0.001) remained associated with chylothorax on regression modeling. The presence of an upper extremity DVT and trisomy 21 were associated with the development of chylothorax. Fluid overload was rare in our population. The presence of positive fluid balance, fluid overload, elevated central venous pressure, and early initiation of fat containing feeds were not associated with chylothorax.

Latent Trajectories of Fluid Balance Are Associated With Outcomes in Cardiac and Aortic Surgery

BACKGROUND

Fluid overload is common in critically ill patients and is associated with worse outcomes. The trends in fluid balance have not been investigated previously. This study used trajectory analysis to investigate the impact of fluid balance trends on patients who had undergone cardiac or aortic surgery.

METHODS

We analyzed patients who underwent cardiac or aortic surgery between August 2005 and March 2015. We excluded patients who died within the first 72 postoperative hours or received chronic dialysis before the surgery. Trajectories of urine and input-output during the first 3 postoperative days were analyzed using a latent class growth model. The primary outcomes were any stage of acute kidney injury (AKI) by Kidney Disease Improving Global Outcomes definition and de novo dialysis.

RESULTS

The in-hospital mortality was 6.6% (70 of the 1063 patients included). The fluid input-output balance trajectories had better association with the primary outcome than urine output trajectories did. The risk of AKI and de novo dialysis were highest in the group with progressively positive fluid balance adjusted by preoperative body weight (AKI: adjusted odds ratio, 7.10; 95% confidence interval, 2.02-24.93; de novo dialysis: odds ratio, 4.54; 95% confidence interval, 1.12-18.38).

CONCLUSIONS

A progressively positive fluid balance is associated with AKI and de novo dialysis in patients undergoing cardiac or aortic surgery.

Renal replacement therapy in the pediatric cardiac intensive care unit

OBJECTIVE

There is an increased risk of mortality in patients in whom acute kidney injury and fluid accumulation develop after cardiothoracic surgery, and the risk is especially high when renal replacement therapy is needed. However, renal replacement therapy remains an essential intervention in managing these patients. The objective of this study was to identify risk factors for mortality in surgical patients requiring renal replacement therapy in a pediatric cardiac intensive care unit.

METHODS

We performed a retrospective review of patients requiring renal replacement therapy for acute kidney injury or fluid accumulation after cardiothoracic surgery between January 2009 and December 2017. Survivors and nonsurvivors were compared with respect to multiple variables, and a multivariable logistic regression analysis was performed to identify independent risk factors associated with mortality.

RESULTS

The mortality rate for the cohort was 75%. Nonsurvivors were younger (nonsurvivors: 0.8 years; interquartile range, 0.1-8.2; survivors: 14.6 years; interquartile range, 4.2-19.7; P = .002) and had a lower weight-for-age z-score (nonsurvivors: -1.5; interquartile range, -3.1 to -0.4; survivors: -0.5; interquartile range, -0.9 to 0.3; P = .02) compared with survivors. There was no difference with respect to fluid accumulation. In multivariable analysis, a longer duration of stage 3 acute kidney injury before initiation of renal replacement therapy was independently associated with mortality (adjusted odds ratio, 1.39; 95% confidence interval, 1.05-1.83; P = .021).

CONCLUSIONS

Mortality in patients requiring renal replacement therapy after congenital heart disease surgery is high. A longer duration of acute kidney injury before renal replacement therapy initiation is associated with increased mortality.

Hypomagnesaemia and other electrolytes imbalances in open and closed pediatrics cardiac surgery

Objective and Background:

During the past decade, many researchers have indicated that open cardiac surgery, using cardiopulmonary bypass, could be an essential factor to induce post-operative electrolyte imbalances which may be followed by life threatening complications such as arrhythmia. Nevertheless, by this time there may be a few researches about comparing of hypomagnesaemia and other electrolyte imbalances between open, on pump, and closed, off pump, heart operation.

Methods:

In this cohort study conducted at Rajaie Heart Center in Tehran from December 2014 to August 2015, we evaluated hypomagnesaemia, hypocalcemia, hypokalemia and hyponatremia in 205 children aged under 15 years who underwent open (101 children) and closed (104 children) cardiac surgery. Repeated measures ANOVA, paired t test and Chi-square/Fisher exact test were used for analysis the data in SPSS version 21.

Results:

According to our study the frequency of electrolyte imbalances including hypomagnesaemia after pediatric heart surgery is relatively high (28.7% hypomagnesaemia at the second day) with more occurrence in closed cardiac operations. There was no significant relationship between hypomagnesaemia and pump time duration (P>0.05). On the other hand, this research indicated that there is significant relationship between post-operative hypomagnesaemia and some other variables including cyanotic heart disease (P=0.01) and concurrent electrolyte imbalance such as hypocalcaemia and hypokalemia (P<0.05).

Conclusion:

Early evaluation and correction of hypomagnesaemia should be considered after both closed and open heart operation.

Fluid Management Practices After Surgery for Congenital Heart Disease: A Worldwide Survey

OBJECTIVES

To determine common practice for fluid management after cardiac surgery for congenital heart disease among pediatric cardiac intensivists.

DESIGN

A survey consisting of 17 questions about fluid management practices after pediatric cardiac surgery. Distribution was done by email, social media, World Federation of Pediatric Intensive and Critical Care Societies website, and World Federation of Pediatric Intensive and Critical Care Societies newsletter using the electronic survey distribution and collection system Research Electronic Data Capture.

SETTING

PICUs around the world.

SUBJECTS

Pediatric intensivists managing children after surgery for congenital heart disease.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One-hundred eight responses from 18 countries and six continents were received. The most common prescribed fluids for IV maintenance are isotonic solutions, mainly NaCl 0.9% (42%); followed by hypotonic fluids (33%) and balanced crystalloids solutions (14%). The majority of the respondents limit total fluid intake to 50% during the first 24 hours after cardiac surgery. The most frequently used fluid as first choice for resuscitation is NaCl 0.9% (44%), the second most frequent choice are colloids (27%). Furthermore, 64% of respondents switch to a second fluid for ongoing resuscitation, 76% of these choose a colloid. Albumin 5% is the most commonly used colloid (61%). Almost all respondents (96%) agree there is a need for research on this topic.

CONCLUSIONS

Our survey demonstrates great variation in fluid management practices, not only for maintenance fluids but also for volume resuscitation. Despite the lack of evidence, colloids are frequently administered. The results highlight the need for further research and evidence-based guidelines on this topic.

First experience with Tolvaptan for the treatment of neonates and infants with capillary leak syndrome after cardiac surgery

Background

Postoperative fluid management in critically ill neonates and infants with capillary leak syndrome (CLS) and extensive volume overload after cardiac surgery on cardiopulmonary bypass is challenging. CLS is often resistant to conventional diuretic therapy, aggravating the course of weaning from invasive ventilation, increasing length of stay on ICU and morbidity and mortality.

Methods

Tolvaptan (TLV, vasopressin type 2 receptor antagonist) was used as an additive diuretic in neonates and infants with CLS after cardiac surgery. Retrospective analysis of 25 patients with CLS including preoperative and postoperative parameters was performed. Multivariate regression analysis was performed to identify predictors for TLV response.

Results

Multivariate analysis identified urinary output during 24 h after TLV administration and mean blood pressure (BP) on day 2 of TLV treatment as predictors for TLV response (AUC = 0.956). Responder showed greater weight reduction (p < 0.0001), earlier weaning from ventilator during TLV (p = 0.0421) and shorter time in the ICU after TLV treatment (p = 0.0155). Serum sodium and serum osmolality increased significantly over time in all patients treated with TLV.

Conclusion

In neonates and infants with diuretic-refractory CLS after cardiac surgery, additional aquaretic therapy with TLV showed an increase in urinary output and reduction in bodyweight in patients classified as TLV responder. Increase in urinary output and mean BP on day 2 of treatment were strong predictors for TLV response.

Electronic supplementary material

The online version of this article (10.1186/s12887-019-1418-6) contains supplementary material, which is available to authorized users.

Multicenter Validation of the Vasoactive-Ventilation-Renal Score as a Predictor of Prolonged Mechanical Ventilation After Neonatal Cardiac Surgery

OBJECTIVES

We sought to validate the Vasoactive-Ventilation-Renal score, a novel disease severity index, as a predictor of outcome in a multicenter cohort of neonates who underwent cardiac surgery.

DESIGN

Retrospective chart review.

SETTING

Seven tertiary-care referral centers.

PATIENTS

Neonates defined as age less than or equal to 30 days at the time of cardiac surgery.

INTERVENTIONS

Ventilation index, Vasoactive-Inotrope Score, serum lactate, and Vasoactive-Ventilation-Renal score were recorded for three postoperative time points: ICU admission, 6 hours, and 12 hours. Peak values, defined as the highest of the three measurements, were also noted. Vasoactive-Ventilation-Renal was calculated as follows: ventilation index + Vasoactive-Inotrope Score + Δ creatinine (change in creatinine from baseline × 10). Primary outcome was prolonged duration of mechanical ventilation, defined as greater than 96 hours. Receiver operative characteristic curves were generated, and abilities of variables to correctly classify prolonged duration of mechanical ventilation were compared using area under the curve values. Multivariable logistic regression modeling was also performed.

MEASUREMENTS AND MAIN RESULTS

We reviewed 275 neonates. Median age at surgery was 7 days (25th-75th percentile, 5-12 d), 86 (31%) had single ventricle anatomy, and 183 (67%) were classified as Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Category 4 or 5. Prolonged duration of mechanical ventilation occurred in 89 patients (32%). At each postoperative time point, the area under the curve for prolonged duration of mechanical ventilation was significantly greater for the Vasoactive-Ventilation-Renal score as compared to the ventilation index, Vasoactive-Inotrope Score, and serum lactate, with an area under the curve for peak Vasoactive-Ventilation-Renal score of 0.82 (95% CI, 0.77-0.88). On multivariable analysis, peak Vasoactive-Ventilation-Renal score was independently associated with prolonged duration of mechanical ventilation, odds ratio (per 1 unit increase): 1.08 (95% CI, 1.04-1.12).

CONCLUSIONS

In this multicenter cohort of neonates who underwent cardiac surgery, the Vasoactive-Ventilation-Renal score was a reliable predictor of postoperative outcome and outperformed more traditional measures of disease complexity and severity.

Fluid Overload in Critically Ill Children

Background: A common practice in the management of critically ill patients is fluid resuscitation. An excessive administration of fluids can lead to an imbalance in fluid homeostasis and cause fluid overload (FO). In pediatric critical care patients, FO can lead to a multitude of adverse effects and increased risk of morbidity. Objectives: To review the literature highlighting impact of FO on a multitude of outcomes in critically-ill children, causative vs. associative relationship of FO with critical illness and current pediatric fluid management guidelines. Data Sources: A literature search was conducted using PubMed/Medline and Embase databases from the earliest available date until June 2017. Data Extraction: Two authors independently reviewed the titles and abstracts of all articles which were assessed for inclusion. The manuscripts of studies deemed relevant to the objectives of this review were then retrieved and associated reference lists hand-searched. Data Synthesis: Articles were segregated into various categories namely pathophysiology and sequelae of fluid overload, assessment techniques, epidemiology and fluid management. Each author reviewed the selected articles in categories assigned to them. All authors participated in the final review process. Conclusions: Recent evidence has purported a relationship between mortality and FO, which can be validated by prospective RCTs (randomized controlled trials). The current literature demonstrates that "clinically significant" degree of FO could be below 10%. The lack of a standardized method to assess FB (fluid balance) and a universal definition of FO are issues that need to be addressed. To date, the impact of early goal directed therapy and utility of hemodynamic parameters in predicting fluid responsiveness remains underexplored in pediatric resuscitation.

Self-Reported Management of IV Fluids and Fluid Accumulation in Children With Acute Respiratory Failure

OBJECTIVES

Observational studies have shown that fluid overload is independently associated with increased morbidity in critically ill children, especially with respiratory pathology. It is unknown if recent evidence has influenced clinical practice. We sought to describe current IV fluid management in pediatric acute respiratory distress syndrome.

DESIGN

Multinational, cross-sectional electronic survey.

SETTING

Pediatric Acute Lung Injury and Sepsis Investigators Network.

SUBJECTS

Pediatric intensivists.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One-hundred fifty-four respondents (43% response rate) had a median 10 years of experience (Q1-Q3, 4-17.8), in ICUs with a median 24 beds (18-36), where 86% provided extracorporeal membrane oxygenation. For maintenance IV fluid, 96% used the "4-2-1" rule to determine rate, and 59% used dextrose with normal saline for content. For fluid resuscitation, 77% use normal saline in 10 milliliters per kilogram aliquots (42%) or as fluid challenges (37%). Less than 20% of respondents reported resuscitating with 20 mL/kg boluses. Documented intake over output is the favored vital sign to assess (75% vs 57%) and guide fluid management (97% vs 14%) over central venous pressure. The majority of respondents chose 10% fluid overload as the threshold to act in children with pediatric acute respiratory distress syndrome. The majority (77%) agreed that fluid accumulation contributes to worse outcomes in pediatric acute respiratory distress syndrome and should be treated. Ninety-one percent reported conservative fluid management in pediatric acute respiratory distress syndrome is likely to be beneficial or protective.

CONCLUSIONS

Pediatric intensivists agree that acting on 10% fluid overload in children with pediatric acute respiratory distress syndrome is important. Decisions are being made largely using intake and output documentation, not central venous pressure. These findings are important for future pediatric acute respiratory distress syndrome interventional trials.

Acute Kidney Injury Defined by Fluid Corrected Creatinine in Neonates After the Norwood Procedure

Background:

Both the Norwood procedure and acute kidney injury (AKI) are associated with significant morbidity and mortality. The impact of AKI by measured and fluid corrected serum creatinine on outcomes after the Norwood procedure has not been previously studied. The purpose of this study was to (1) identify the incidence of AKI, (2) determine AKI risk factors, and (3) evaluate outcomes in patients with AKI using both measured and fluid corrected serum creatinine.

Methods:

Single-center retrospective chart review from 2009 to 2015 including neonates who underwent the Norwood procedure. Acute kidney injury was defined by the Kidney Disease Improving Global Outcomes staging criteria using both measured and fluid corrected serum creatinine. Multivariable logistic regression analysis was performed to determine the risk factors associated with AKI.

Results:

Ninety-five neonates underwent the Norwood procedure. Correcting for fluid overload increased the incidence of AKI from 40% to 44%, increased AKI severity in 15 patients, and improved the identification of adverse outcomes associated with AKI. Patients palliated with the modified Blalock-Taussig shunt (mBTS) had a 9.4 greater odds of fluid corrected AKI compared to those palliated with a right ventricle to pulmonary artery conduit (95% confidence interval [95% CI]: 1.68-52.26, P = .01). A higher vasoactive inotrope score (VIS) on postoperative day (POD) 0 was associated with fluid corrected AKI (odds ratio: 1.20, 95% CI: 1.06-1.35; P = .003).

Conclusions:

Acute kidney injury is common after the Norwood procedure. Correcting creatinine for fluid balance revealed new cases of AKI. Use of an mBTS and higher VIS on POD 0 were associated with increased risk of AKI.

Management of Fluid Overload in the Pediatric ICU

The implications and management of fluid overload in pediatric critical care remain areas of ongoing controversy. Consensus definitions and methods of quantitating fluid overload continue to evolve, paralleling our growing understanding of fluid dynamics in critically ill patients. Fluid overload has been associated with adverse outcomes in some patient populations; guidelines for fluid management therapies are sparse and have little supporting data. Conflicting data for efficacy of therapies such as diuretic medications and renal replacement therapy are likely reflective of an incomplete understanding of the dynamic relationship between critical illness and fluid overload. Although some guidance regarding diuresis, continuous renal replacement therapy, and fluid balance goals is elucidated in the following chapters, it is important to recognize that further research into these management strategies is required before standardized approaches to management can be established.

Useful References in Pediatric Cardiac Intensive Care: The 2017 Update

OBJECTIVES

Pediatric cardiac intensive care continues to evolve, with rapid advances in knowledge and improvement in clinical outcomes. In the past, the Board of Directors of the Pediatric Cardiac Intensive Care Society created and subsequently updated a list of sentinel references focused on the care of critically ill children with congenital and acquired heart disease. The objective of this article is to provide clinicians with a compilation and brief summary of updated and useful references that have been published since 2012.

DATA SELECTION

Pediatric Cardiac Intensive Care Society members were solicited via a survey sent out between March 20, 2017, and April 28, 2017, to provide important references that have impacted clinical care. The survey was sent to approximately 523 members. Responses were received from 45 members, of which some included multiple references.

DATA EXTRACTION

Following review of the list of references, and removing editorials, references were compiled by the first and last author. The final list was submitted to members of the society's Research Briefs Committee, who ranked each publication.

DATA SYNTHESIS

Rankings were compiled and the references with the highest scores included. Research Briefs Committee members ranked the articles from 1 to 3, with one being highly relevant and should be included and 3 being less important and should be excluded. Averages were computed, and the top articles included in this article. The first (K.C.U.) and last author (K.M.G.) reviewed and developed summaries of each article.

CONCLUSIONS

This article contains a compilation of useful references for the critical care of children with congenital and acquired heart disease published in the last 5 years. In conjunction with the prior version of this update in 2012, this article may be used as an educational reference in pediatric cardiac intensive care.

Fluid overload independent of acute kidney injury predicts poor outcomes in neonates following congenital heart surgery

BACKGROUND

Fluid overload (FO) is common after neonatal congenital heart surgery and may contribute to mortality and morbidity. It is unclear if the effects of FO are independent of acute kidney injury (AKI).

METHODS

This was a retrospective cohort study which examined neonates (age < 30 days) who underwent cardiopulmonary bypass in a university-affiliated children's hospital between 20 October 2010 and 31 December 2012. Demographic information, risk adjustment for congenital heart surgery score, surgery type, cardiopulmonary bypass time, cross-clamp time, and vasoactive inotrope score were recorded. FO [(fluid in-out)/pre-operative weight] and AKI defined by Kidney Disease Improving Global Outcomes serum creatinine criteria were calculated. Outcomes were all-cause, in-hospital mortality and median postoperative hospital and intensive care unit lengths of stay.

RESULTS

Overall, 167 neonates underwent cardiac surgery using cardiopulmonary bypass in the study period, of whom 117 met the inclusion criteria. Of the 117 neonates included in the study, 76 (65%) patients developed significant FO (>10%), and 25 (21%) developed AKI ≥ Stage 2. When analyzed as FO cohorts (< 10%,10-20%, > 20% FO), patients with greater FO were more likely to have AKI (9.8 vs. 18.2 vs. 52.4%, respectively, with AKI ≥ stage 2; p = 0.013) and a higher vasoactive-inotrope score, and be premature. In the multivariable regression analyses of patients without AKI, FO was independently associated with hospital and intensive care unit lengths of stay [0.322 extra days (p = 0.029) and 0.468 extra days (p < 0.001), respectively, per 1% FO increase). In all patients, FO was also associated with mortality [odds ratio 1.058 (5.8% greater odds of mortality per 1% FO increase); 95% confidence interval 1.008,1.125;p = 0.032].

CONCLUSIONS

Fluid overload is an important independent contributor to outcomes in neonates following congenital heart surgery. Careful fluid management after cardiac surgery in neonates with and without AKI is warranted.

Association Between Fluid Balance and Outcomes in Critically Ill Children: A Systematic Review and Meta-analysis

IMPORTANCE

After initial resuscitation, critically ill children may accumulate fluid and develop fluid overload. Accruing evidence suggests that fluid overload contributes to greater complexity of care and worse outcomes.

OBJECTIVE

To describe the methods to measure fluid balance, define fluid overload, and evaluate the association between fluid balance and outcomes in critically ill children.

DATA SOURCES

Systematic search of MEDLINE, EMBASE, Cochrane Library, trial registries, and selected gray literature from inception to March 2017.

STUDY SELECTION

Studies of children admitted to pediatric intensive care units that described fluid balance or fluid overload and reported outcomes of interest were included. No language restrictions were applied.

DATA EXTRACTION AND SYNTHESIS

All stages were conducted independently by 2 reviewers. Data extracted included study characteristics, population, fluid metrics, and outcomes. Risk of bias was assessed using the Newcastle-Ottawa Scale. Narrative description of fluid assessment methods and fluid overload definitions was done. When feasible, pooled analyses were performed using random-effects models.

MAIN OUTCOMES AND MEASURES

Mortality was the primary outcome. Secondary outcomes included treatment intensity, organ failure, and resource use.

RESULTS

A total of 44 studies (7507 children) were included in this systematic review and meta-analysis. Of those, 27 (61%) were retrospective cohort studies, 13 (30%) were prospective cohort studies, 3 (7%) were case-control studies, and 1 study (2%) was a secondary analysis of a randomized trial. The proportion of children with fluid overload varied by case mix and fluid overload definition (median, 33%; range, 10%-83%). Fluid overload, however defined, was associated with increased in-hospital mortality (17 studies [n = 2853]; odds ratio [OR], 4.34 [95% CI, 3.01-6.26]; I2 = 61%). Survivors had lower percentage fluid overload than nonsurvivors (22 studies [n = 2848]; mean difference, -5.62 [95% CI, -7.28 to -3.97]; I2 = 76%). After adjustment for illness severity, there was a 6% increase in odds of mortality for every 1% increase in percentage fluid overload (11 studies [n = 3200]; adjusted OR, 1.06 [95% CI, 1.03-1.10]; I2 = 66%). Fluid overload was associated with increased risk for prolonged mechanical ventilation (>48 hours) (3 studies [n = 631]; OR, 2.14 [95% CI, 1.25-3.66]; I2 = 0%) and acute kidney injury (7 studies [n = 1833]; OR, 2.36 [95% CI, 1.27-4.38]; I2 = 78%).

CONCLUSIONS AND RELEVANCE

Fluid overload is common and is associated with substantial morbidity and mortality in critically ill children. Additional research should now ideally focus on interventions aimed to mitigate the potential for harm associated with fluid overload.

Cell-Free Plasma Hemoglobin and Male Gender Are Risk Factors for Acute Kidney Injury in Low Risk Children Undergoing Cardiopulmonary Bypass

OBJECTIVES

To determine the relationship between the production of cell-free plasma hemoglobin and acute kidney injury in infants and children undergoing cardiopulmonary bypass for cardiac surgery.

DESIGN

Prospective observational study.

SETTING

Twelve-bed cardiac ICU in a university-affiliated children's hospital.

PATIENTS

Children were prospectively enrolled during their preoperative outpatient appointment with the following criteria: greater than 1 month to less than 18 years old, procedures requiring cardiopulmonary bypass, no preexisting renal dysfunction.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma and urine were collected at baseline (in a subset), the beginning and end of cardiopulmonary bypass, and 2 hours and 24 hours after cardiopulmonary bypass in 60 subjects. Levels of plasma hemoglobin increased during cardiopulmonary bypass and were associated (p < 0.01) with cardiopulmonary bypass duration (R = 0.22), depletion of haptoglobin at end and 24 hours after cardiopulmonary bypass (R = 0.12 and 0.15, respectively), lactate dehydrogenase levels at end cardiopulmonary bypass (R = 0.27), and change in creatinine (R = 0.12). Forty-three percent of patients developed acute kidney injury. There was an association between plasma hemoglobin level and change in creatinine that varied by age (overall [R = 0.12; p < 0.01]; in age > 2 yr [R = 0.22; p < 0.01]; and in < 2 yr [R = 0.03; p = 0.42]). Change in plasma hemoglobin and male gender were found to be risk factors for acute kidney injury (odds ratio, 1.02 and 3.78, respectively; p < 0.05).

CONCLUSIONS

Generation of plasma hemoglobin during cardiopulmonary bypass and male gender are associated with subsequent renal dysfunction in low-risk pediatric patients, especially in those older than 2 years. Further studies are needed to determine whether specific subgroups of pediatric patients undergoing cardiopulmonary bypass would benefit from potential treatments for hemolysis and plasma hemoglobin-associated renal dysfunction.

Factors Associated With Pediatric Ventilator-Associated Conditions in Six U.S. Hospitals: A Nested Case-Control Study

OBJECTIVES

A newly proposed surveillance definition for ventilator-associated conditions among neonatal and pediatric patients has been associated with increased morbidity and mortality among ventilated patients in cardiac ICU, neonatal ICU, and PICU. This study aimed to identify potential risk factors associated with pediatric ventilator-associated conditions.

DESIGN

Retrospective cohort.

SETTING

Six U.S. hospitals PATIENTS:: Children less than or equal to 18 years old ventilated for greater than or equal to 1 day.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We identified children with pediatric ventilator-associated conditions and matched them to children without ventilator-associated conditions. Medical records were reviewed for comorbidities and acute care factors. We used bivariate and multivariate conditional logistic regression models to identify factors associated with ventilator-associated conditions. We studied 192 pairs of ventilator-associated conditions cases and matched controls (113 in the PICU and cardiac ICU combined; 79 in the neonatal ICU). In the PICU/cardiac ICU, potential risk factors for ventilator-associated conditions included neuromuscular blockade (odds ratio, 2.29; 95% CI, 1.08-4.87), positive fluid balance (highest quartile compared with the lowest, odds ratio, 7.76; 95% CI, 2.10-28.6), and blood product use (odds ratio, 1.52; 95% CI, 0.70-3.28). Weaning from sedation (i.e., decreasing sedation) or interruption of sedation may be protective (odds ratio, 0.44; 95% CI, 0.18-1.11). In the neonatal ICU, potential risk factors included blood product use (odds ratio, 2.99; 95% CI, 1.02-8.78), neuromuscular blockade use (odds ratio, 3.96; 95% CI, 0.93-16.9), and recent surgical procedures (odds ratio, 2.19; 95% CI, 0.77-6.28). Weaning or interrupting sedation was protective (odds ratio, 0.07; 95% CI, 0.01-0.79).

CONCLUSIONS

In mechanically ventilated neonates and children, we identified several possible risk factors associated with ventilator-associated conditions. Next steps include studying propensity-matched cohorts and prospectively testing whether changes in sedation management, transfusion thresholds, and fluid management can decrease pediatric ventilator-associated conditions rates and improve patient outcomes.

Drug Flow Through Clinical Infusion Systems: How Modeling of the Common-volume Helps Explain Clinical Events

This review aims to describe analytic models of drug infusion that demonstrate the impact of the infusion system common-volume on drug delivery. The common-volume of a drug infusion system is defined as the volume residing between the point where drug and inert carrier streams meet and the patient’s blood. We describe 3 sets of models. The first is quantitative modeling which includes algebraic mathematical constructs and forward-difference computational simulation. The second set of models is with in vitro benchtop simulation of clinical infusion system architecture. This modeling employs devices including pumps, manifolds, tubing and catheters used in patient care. The final set of models confirms in vitro findings with pharmacodynamic endpoints in living large mammals. Such modeling reveals subtle but important issues inherent in drug infusion therapy that can potentially lead to patient instability and morbidity. The common-volume is an often overlooked reservoir of drugs, especially when infusions flows are slowed or stopped. Even with medications and carriers flowing, some mass of drug always resides within this common-volume. This reservoir of drug can be inadvertently delivered into patients. When infusions are initiated, or when dose rate or carrier flow is altered, there can be a significant lag between intended and actual drug delivery. In the case of vasoactive and inotropic drug infusions, these unappreciated time delays between intended and actual drug delivery can lead to iatrogenic hemodynamic instability. When a drug infusion is discontinued, drug delivery continues until the common-volume is fully cleared of residual drug by the carrier. The findings from all 3 sets of models described in this review indicate that minimizing the common-volume of drug infusion systems may enhance patient safety. The presented models may also be configured into teaching tools and possibly point to technological solutions that might mitigate sources of iatrogenic patient lability.

Fluid Overload and Cumulative Thoracostomy Output Are Associated With Surgical Site Infection After Pediatric Cardiothoracic Surgery

OBJECTIVES

To determine the impact of cumulative, postoperative thoracostomy output, amount of bolus IV fluids and peak fluid overload on the incidence and odds of developing a deep surgical site infection following pediatric cardiothoracic surgery.

DESIGN

A single-center, nested, retrospective, matched case-control study.

SETTING

A 26-bed cardiac ICU in a 303-bed tertiary care pediatric hospital.

PATIENTS

Cases with deep surgical site infection following cardiothoracic surgery were identified retrospectively from January 2010 through December 2013 and individually matched to controls at a ratio of 1:2 by age, gender, Risk Adjustment for Congenital Heart Surgery score, Society of Thoracic Surgeons-European Association for Cardiothoracic Surgery category, primary cardiac diagnosis, and procedure.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Twelve cases with deep surgical site infection were identified and matched to 24 controls without detectable differences in perioperative clinical characteristics. Deep surgical site infection cases had larger thoracostomy output and bolus IV fluid volumes at 6, 24, and 48 hours postoperatively compared with controls. For every 1 mL/kg of thoracostomy output, the odds of developing a deep surgical site infection increase by 13%. By receiver operative characteristic curve analysis, a cutoff of 49 mL/kg of thoracostomy output at 48 hours best discriminates the development of deep surgical site infection (sensitivity 83%, specificity 83%). Peak fluid overload was greater in cases than matched controls (12.5% vs 6%; p < 0.01). On receiver operative characteristic curve analysis, a threshold value of 10% peak fluid overload was observed to identify deep surgical site infection (sensitivity 67%, specificity 79%). Conditional logistic regression of peak fluid overload greater than 10% on the development of deep surgical site infection yielded an odds ratio of 9.4 (95% CI, 2-46.2).

CONCLUSIONS

Increased postoperative peak fluid overload and cumulative thoracostomy output were associated with deep surgical site infection after pediatric cardiothoracic surgery. We suspect the observed increased thoracostomy output, fluid overload, and IV fluid boluses may have altered antimicrobial prophylaxis. Although analysis of additional pharmacokinetic data is warranted, providers may consider modification of antimicrobial prophylaxis dosing or alterations in fluid management and diuresis in response to assessment of peak fluid overload and fluid volume shifts in the immediate postoperative period.

Drug Infusion Systems: Technologies, Performance, and Pitfalls

This review aims to broadly describe drug infusion technologies and raise subtle but important issues arising from infusion therapy that can potentially lead to patient instability and morbidity. Advantages and disadvantages of gravity-dependent drug infusion are described and compared with electromechanical approaches for precise control of medication infusion, including large-volume peristaltic and syringe pumps. This review discusses how drugs and inert carriers interact within infusion systems and outlines several complexities and potential sources of drug error. Major topics are (1) the importance of the infusion system dead volume; (2) the quantities of coadministered fluid and the concept of microinfusion; and (3) future directions for drug infusion.The infusion system dead volume resides between the point where drug and inert carrier streams meet and the patient's blood. The dead volume is an often forgotten reservoir of drugs, especially when infusion flows slow or stop. Even with medications and carriers flowing, some mass of drug always resides within the dead volume. This reservoir of drug can be accidentally delivered into patients. When dose rate is changed, there can be a significant lag between intended and actual drug delivery. When a drug infusion is discontinued, drug delivery continues until the dead volume is fully cleared of residual drug by the carrier. When multiple drug infusions flow together, a change in any drug flow rate transiently affects the rate of delivery of all the others. For all of these reasons, the use of drug infusion systems with smaller dead volumes may be advantageous.For critically ill patients requiring multiple infusions, the obligate amount of administered fluid can contribute to volume overload. Recognition of the risk of overload has given rise to microinfusion strategies wherein drug solutions are highly concentrated and infused at low rates. However, potential risks associated with the dead volume may be magnified with microinfusion. All of these potential sources for adverse events relating to the infusion system dead volume illustrate the need for continuing education of clinical personnel in the complexities of drug delivery by infusion.This review concludes with an outline of future technologies for managing drug delivery by continuous infusion. Automated systems based on physiologic signals and smart systems based on physical principles and an understanding of dead volume may mitigate against adverse patient events and clinical errors in the complex process of drug delivery by infusion.

Pediatric Extracorporeal Membrane Oxygenation

Extracorporeal life support is a modified form of cardiopulmonary bypass. Experience in extracorporeal membrane oxygenation (ECMO) has come largely from the neonatal population. Most centers have transitioned the ECMO pumps from roller pumps to centrifugal technology. Modes of support include venovenous for respiratory support and venoarterial for cardiac support. "Awake" ECMO is the trend with extubation and tracheostomy on the rise. Fluid overload is common and managed with diuretics or hemofiltration. Nutrition is important and provided enterally or via total parenteral nutrition. Overall survival for pediatric cardiac and respiratory ECMO has remained at approximately 50% to 60%.

Novel Pump Control Technology Accelerates Drug Delivery Onset in a Model of Pediatric Drug Infusion

BACKGROUND

Laboratory data suggest that newly initiated drug infusions reach steady-state delivery after a significant time lag. Depending on drug and carrier flow rates and the infusion system's common volume, lag times may exceed 20 or more minutes, especially in the neonatal/pediatric critical care environment. This study tested the hypothesis that a computer-executed algorithm controlling infusion pumps in a coordinated fashion predictably hastens the achievement of the intended steady-state drug delivery in a model of neonatal/pediatric drug infusion.

METHODS

We constructed an in vitro model of neonatal/pediatric drug infusions through a pediatric 4-Fr central venous catheter at total system flows of 2 mL/h or 12 mL/h, representing a clinically relevant infusion range. Methylene blue served as the model infused drug for quantitative analysis. A novel algorithm, based on Taylor Dispersion Theory of fluid flow through tubes and executed by a computer, generated flow patterns that controlled and coordinated drug and carrier delivery by syringe pumps. We measured the time to achieve the intended steady-state drug delivery by conventional initiation of the drug infusion ("turning on the drug pump") and by algorithm-controlled infusion initiation.

RESULTS

At 2 mL/h total system flow, application of the algorithm reduced the time to achieve half of the intended drug delivery rate (T50) from 17 minutes [17, 18] to 3 minutes [3, 3] (median, interquartile range). At 12 mL/h total system flow, application of the algorithm reduced T50 from 6 minutes [6, 7] to 3 minutes [3, 3] The bootstrapped median difference is -14 (95% confidence interval [CI], -16 to -12, adjusted P=.00192) for 2 mL/h flow and -3 (95% CI, -4 to -3, adjusted P=.02061) for 12 mL/h flow. Compared with conventional initiation, the additional fluid required by the algorithm-directed infusion was 0.43 and 1.03 mL for the low- and high-infusion rates, respectively.

CONCLUSIONS

The output of infusion pumps can be predictably controlled and coordinated by a computer-executed algorithm in a model of neonatal/pediatric drug infusions. Application of an algorithm can reduce the time to achieve the intended rate of infused drug delivery with minimal incremental volume administration.

Hypertonic saline in critical illness - A systematic review

INTRODUCTION

The optimal approach to fluid management in critically ill patients is highly debated. Fluid resuscitation using hypertonic saline was used in the past for more than thirty years, but has recently disappeared from clinical practice. Here we provide an overview on the currently available literature on effects of hypertonic saline infusion for fluid resuscitation in the critically ill.

METHODS

Systematic analysis of reports of clinical trials comparing effects of hypertonic saline as resuscitation fluid to other available crystalloid solutions. A literature search of MEDLINE and the Cochrane Controlled Clinical trials register (CENTRAL) was conducted to identify suitable studies.

RESULTS

The applied search strategy produced 2284 potential publications. After eliminating doubles, 855 titles and abstracts were screened and 40 references retrieved for full text analysis. At total of 25 scientific studies meet the prespecified inclusion criteria for this study.

CONCLUSION

Fluid resuscitation using hypertonic saline results in volume expansion and less total infusion volume. This may be of interest in oedematous patients with intravascular volume depletion. When such strategies are employed, renal effects may differ markedly according to prior intravascular volume status. Hypertonic saline induced changes in serum osmolality and electrolytes return to baseline within a limited period in time. Sparse evidence indicates that resuscitation with hypertonic saline results in less perioperative complications, ICU days and mortality in selected patients. In conclusion, the use of hypertonic saline may have beneficial features in selected critically ill patients when carefully chosen. Further clinical studies assessing relevant clinical outcomes are warranted.

[Association between fluid overload and acute renal injury after congenital heart disease surgery in infants]

OBJECTIVE

To study the association between fluid overload and acute kidney injury (AKI) after congenital heart disease surgery in infants.

METHODS

A retrospective analysis was performed on 88 infants aged less than 6 months who underwent a radical surgery for congenital heart disease. The treatment outcomes were compared between the infants with AKI after surgery and those without. The effect of cumulative fluid overload on treatment outcomes 2 days after surgery was analyzed. The risk factors for the development of AKI after surgery were assessed by logistic regression analysis.

RESULTS

Compared with those without AKI after surgery, the patients with AKI had younger age, lower body weights, higher serum creatinine levels and higher vasoactive-inotropic score, as well as longer durations of intraoperative extracorporeal circulation and aortic occlusion (P<0.05). Compared with those without AKI after surgery, the patients with AKI had a higher transfusion volume, a higher incidence rate of low cardiac output syndrome, a longer duration of mechanical ventilation, a longer length of stay in the intensive care unit (ICU), a longer length of hospital stay, a higher application rate of extracorporeal membrane oxygenation, a higher 30-day mortality rate, and higher levels of cumulative fluid overload 2 and 3 days after surgery (P<0.05). The logistic regression analysis showed that fluid overload and low cardiac output syndrome were major risk factors for the development of AKI after surgery. The children with cumulative fluid overload >5% at 2 days after surgery had a higher incidence rate of low cardiac output syndrome, a longer duration of mechanical ventilation, a longer length of stay in the ICU, a longer length of hospital stay, and a higher mortality rate (P<0.05).

CONCLUSIONS

Infants with fluid overload after surgery for congenital heart disease tend to develop AKI, and fluid overload may be associated with poor outcomes after surgery.

Standard concentration infusions in paediatric intensive care: the clinical approach

The use of standard concentrations of intravenous infusions has been advocated by international organisations to increase intravenous medication safety in paediatric and neonatal critical care. However, there is no guidance on how to identify and implement these infusions leading to great interunit variability.

OBJECTIVE

To identify the most appropriate clinical concentrations required by our paediatric intensive care unit (PICU) population with regard to accuracy of delivery and overall fluid allowance.

METHODS

Firstly a matrix was used to balance the concentration, dose and infusion volume (weight range 1.5-50 kg). Results were further refined considering: patient fluid allowance based on fluid volume targets, infusion pump accuracy and challenging each infusion against clinical scenarios requiring administration of multiple drug infusions found in PICU. Consideration was given to the standard concentrations routinely used in adults, in order to assess whether alignment with paediatrics was possible for some of the concentrations proposed. Finally a risk assessment of the infusions was conducted using the NPSA 20 tool.

KEY FINDINGS

Twenty-five drugs identified as the most commonly used intravenous infusions in the unit. For the majority of the medicines, three weight bands of standard concentrations were necessary to cover the children's weight ranges and kept within predefined fluid requirements and accuracy of delivery.

CONCLUSIONS

This work shows a patient focused systematic approach for defining and evaluating standardised concentrations in intensive care children.