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

Fluid balance versus weighing: A comparison in ICU patients: A single center observational study

BACKGROUND

The fluid balance is a critical parameter in intensive care units (ICU) as it provides information about the patient's volume status. However, the accuracy of fluid balance measurements is often compromised due to the complexity and repetition of actions involved. Additionally, the fluid balance could be recalculated for insensible fluid loss. Weighing is an alternative method to estimate the patient's volume status. Built-in scales in beds make patient weighing easier and less time-consuming, allowing clinicians to intervene more quickly on existing treatments.

AIM

This study compares fluid balance, and body weight changes over time in ICU patients. Furthermore, it seeks to determine the degree of congruence between the fluid balance corrected for insensible fluid loss and daily body weight in ICU patients.

METHODS

A single-center observational study was conducted in an ICU of a university hospital. All consecutive patients admitted to a bed with an integrated weighing scale were eligible. Exclusion criteria were (1) body weight ≥254,4 kilograms; (2) oral nutrition; (3) a flush catheter or balance; (4) only a single weight measurement; (5) delta body weight change of ≥5kg in 12 hours. Weights and fluid balances were obtained every 12 hours.

RESULTS

We obtained 2282 measurements (n = 187 patients). The correlation between weight and fluid balance was weak (r = 0.274). After adjusting the fluid balance for insensible fluid loss, the correlation remained weak (r = 0,268). Bland Altman analysis revealed a wide confidence interval for both the fluid balance and corrected fluid balance versus weight.

CONCLUSION AND IMPLICATIONS OF KEY FINDINGS

This study shows a weak correlation between weight and fluid balance. Therefore, when monitoring the volume status in the ICU, fluid balance and weight should both be taken into account. This two-pronged approach is crucial because it provides more control over erroneous fluid balance or weighing measurements.

Comparison of Bioelectrical Impedance Analysis (BIA)-Derived Parameters in Healthy Volunteers and Critically Ill Patients

OBJECTIVE

To compare bioelectrical impedance analysis (BIA)-derived parameters in healthy volunteers and critically ill patients and to assess its prognostic value in an ICU patient cohort.

DESIGN

Retrospective, observational data analysis.

SETTING

Single centre, tertiary-level ICU (Ziekenhuis Netwerk Antwerpen, ZNA Stuivenberg Hospital).

PATIENTS

101 patients and 101 healthy subjects, participants of International Fluid Academy Days.

MEASUREMENTS AND MAIN RESULTS

Compared to healthy volunteers, both male and female ICU patients had significantly higher values for total body water (TBW), extracellular water (ECW), extracellular fluid (ECF), plasma, and interstitial fluid volumes. The phase angle was significantly lower and the malnutrition index was significantly higher in ICU patients, regardless of gender. Non-survivors in the ICU had significantly higher extracellular water content (ECW, 50.7 ± 5.1 vs. 48.9 ± 4.3%, p = 0.047) and accordingly significantly lower intracellular water (ICW, 49.2 ± 5.1 vs. 51.1 ± 4.3%, p = 0.047). The malnutrition index was also significantly higher in non-survivors compared to survivors (0.94 ± 0.17 vs. 0.87 ± 0.16, p = 0.048), as was the capillary leak index (ECW/ICW).

CONCLUSIONS

Compared to healthy volunteers, this study observed a higher malnutrition index and TBW in ICU patients with an accumulation of fluids in the extracellular compartment. ICU non-survivors showed similar results, indicating that ICU patients and a fortiori non-survivors are generally overhydrated, with increased TBW and ECW, and more undernourished, as indicated by a higher malnutrition index.

Postoperative Weight Gain within Enhanced Recovery after Cardiac Surgery

Optimal fluid therapy during perioperative care as part of enhanced recovery after cardiac surgery (ERACS) should improve the outcome. Our objective was finding out the effects of fluid overload on outcome and mortality within a well-established ERACS program. All consecutive patients undergoing cardiac surgery between January 2020 and December 2021 were enrolled. According to ROC curve analysis, a cut-off of ≥7 kg (group M, n = 1198) and <7 kg (group L, n = 1015) was defined. A moderate correlation was shown between weight gain and fluid balance r = 0.4, and a simple linear regression was significant p < 0.0001, R² = 0.16. Propensity score matching showed that increased weight gain was associated with a longer hospital length of stay (LOS) (L 8 [3] d vs. M 9 [6] d, p < 0.0001), an increased number of patients who received pRBCs (L 311 (36%) vs. M 429 (50%), p < 0.0001), and a higher incidence of postoperative acute kidney injury (AKI) (L 84 (9.8%) vs. M 165 (19.2%), p < 0.0001). Weight gain can easily represent fluid overload. Fluid overload after cardiac surgery is common and is associated with prolonged hospital LOS and increases the incidence of AKI.

Bioimpedance spectroscopy fluid analysis in acute high-risk abdominal surgery, a prospective clinician-blinded observational feasibility study

Objective assessment of fluid status in critical surgical care may help optimize perioperative fluid administration and prevent postoperative fluid retention. We evaluated the feasibility of hydration status and fluid distribution assessment by Bioimpedance spectroscopy Analysis (BIA) in patients undergoing acute high-risk abdominal (AHA) surgery. This observational study included 73 patients undergoing AHA surgery. During the observational period (0-120 h), we registered BIA calculated absolute fluid overload (AFO) and relative fluid overload (RFO), defined as AFO/extracellular water ratio, as well as cumulative fluid balance and weight. Based on RFO values, hydration status was classified into three categories: dehydrated (RFO <  - 10%), normohydrated (- 10% ≤ RFO ≤  + 15%), overhydrated RFO > 15%. We performed a total of 365 BIA measurements. Preoperative overhydration was found in 16% of patients, increasing to 66% by postoperative day five. The changes in BIA measured AFO correlated with the cumulative fluid balance (r2 = 0.44, p < .001), and change in weight (r2 = 0.55, p < .0001). Perioperative overhydration measured with BIA was associated with worse outcome compared to patients with normo- or dehydration. We have demonstrated the feasibility of obtaining perioperative bedside BIA measurements in patients undergoing AHA surgery. BIA measurements correlated with fluid balance, weight changes, and postoperative clinical complications. BIA-assessed fluid status might add helpful information to guide fluid management in patients undergoing AHA surgery.

Effect of Change in Body Weight on Clinical Outcomes in Critically Ill Patients

Background

Intravenous fluid optimization is an essential component of managing patients in a critical care setting. A cumulative positive fluid balance is consistent with poor outcomes in patients admitted to the intensive care unit (ICU). The overall utility of net cumulative fluid balance as a surrogate for assessing fluid overload has been interrogated.

Materials and methods

This study was a prospective single-center observational study, which was done to correlate body weight changes with fluid balance in ICU patients and evaluate its impact on clinical outcomes. Inclusion criteria consisted of adult patients who were admitted to the critical care unit on specialized beds with integrated weighing scales between September 2017 and December 2018. The evaluation of the effect of changes in body weight on ICU survival was the primary objective of the study.

Results

We enrolled 105 patients in this study. The ICU mortality was 23.80% with non-survivors showing more weight gain than the survivors. Statistically significant weight gain was documented in the non-survivors on days 3 and 4 (1.9 vs 1.05; p = 0.0084 and 2.6 vs 1.6; p = 0.0030) of ICU admission. Non-survivors had greater cumulative positive fluid balance on fourth, fifth, and sixth days post-ICU admission when compared to survivors (3586 vs 1659 mL, p = 0.0322; 5418 vs 1255 mL, p = 0.0017; and 5430 vs 2305 mL p = 0.0264, respectively). In multivariate regression analysis, cumulative fluid balance did not correlate with days on mechanical ventilation or length of stay in ICU. Changes in body weight and cumulative fluid balance showed a good correlation.

Conclusion

In patients admitted to the ICU, weight gain on third and fourth days of admission is concordant with increased ICU mortality. Body weight changes were seen to correlate well with the cumulative fluid balance.

How to cite this article

Mishra RK, Pande A, Ramachandran R, Trikha A, Singh PM, Rewari V. Effect of Change in Body Weight on Clinical Outcomes in Critically Ill Patients. Indian J Crit Care Med 2021;25(9):1042–1048.

The Correspondence Between Fluid Balance and Body Weight Change Measurements in Critically Ill Adult Patients

Introduction

Positive fluid status has been associated with a worse prognosis in intensive care unit (ICU) patients. Given the potential for errors in the calculation of fluid balance totals and the problem of accounting for indiscernible fluid losses, measurement of body weight change is an alternative non-invasive method commonly used for estimating body fluid status. The objective of the study is to compare the measurements of fluid balance and body weight changes over time and to assess their association with ICU mortality.

Methods

This prospective observational study was conducted in the 34-bed multidisciplinary ICU of a tertiary teaching hospital in southern Brazil. Adult patients were eligible if their expected length of stay was more than 48 hours, and if they were not receiving an oral diet. Clinical demographic data, daily and cumulative fluid balance with and without indiscernible water loss, and daily and total body weight changes were recorded. Agreement between daily fluid balance and body weight change, and between cumulative fluid balance and total body weight change were calculated.

Results

Cumulative fluid balance and total body weight change differed significantly among survivors and non survivors respectively, +2.53L versus +5.6L (p= 0.012) and -3.05kg vs -1.1kg (p= 0.008). The average daily difference between measured fluid balance and body weight was +0.864 L/kg with a wide interval: -3.156 to +4.885 L/kg, which remained so even after adjustment for indiscernible losses (mean bias: +0.288; limits of agreement between -3.876 and +4.452 L/kg). Areas under ROC curve for cumulative fluid balance, cumulative fluid balance with indiscernible losses and total body weight change were, respectively, 0.65, 0.56 and 0.65 (p= 0.14).

Conclusion

The results indicated the absence of correspondence between fluid balance and body weight change, with a more significant discrepancy between cumulative fluid balance and total body weight change. Both fluid balance and body weight changes were significantly different among survivors and non-survivors, but neither measurement discriminated ICU mortality.

Fluid Overload

Fluid overload (FO) is characterized by hypervolemia, edema, or both. In clinical practice it is usually suspected when a patient shows evidence of pulmonary edema, peripheral edema, or body cavity effusion. FO may be a consequence of spontaneous disease, or may be a complication of intravenous fluid therapy. Most clinical studies of the association of FO with fluid therapy and risk of harm define it in terms of an increase in body weight of at least 5–10%, or a positive fluid balance of the same magnitude when fluid intake and urine output are measured. Numerous observational clinical studies in humans have demonstrated an association between FO, adverse events, and mortality, as have two retrospective observational studies in dogs and cats. The risk of FO may be minimized by limiting resuscitation fluid to the smallest amount needed to optimize cardiac output and then limiting maintenance fluid to the amount needed to replace ongoing normal and pathological losses of water and sodium.

Bioelectrical impedance analysis-guided fluid management promotes primary fascial closure after open abdomen: a randomized controlled trial

BACKGROUND

Fluid overload (FO) after resuscitation is frequent and contributes to adverse outcomes among postinjury open abdomen (OA) patients. Bioelectrical impedance analysis (BIA) is a promising tool for monitoring fluid status and FO. Therefore, we sought to investigate the efficacy of BIA-directed fluid resuscitation among OA patients.

METHODS

A pragmatic, prospective, randomized, observer-blind, single-center trial was performed for all trauma patients requiring OA between January 2013 and December 2017 to a national referral center. A total of 140 postinjury OA patients were randomly assigned in a 1:1 ratio to receive either a BIA-directed fluid resuscitation (BIA) protocol that included fluid administration with monitoring of hemodynamic parameters and different degrees of interventions to achieve a negative fluid balance targeting the hydration level (HL) measured by BIA or a traditional fluid resuscitation (TRD) in which clinicians determined the fluid resuscitation regimen according to traditional parameters during 30 days of ICU management. The primary outcome was the 30-day primary fascial closure (PFC) rate. The secondary outcomes included the time to PFC, postoperative 7-day cumulative fluid balance (CFB) and adverse events within 30 days after OA. The Kaplan-Meier method and the log-rank test were utilized for PFC after OA. A generalized linear regression model for the time to PFC and CFB was built.

RESULTS

A total of 134 patients completed the trial (BIA, n = 66; TRD, n = 68). The BIA patients were significantly more likely to achieve PFC than the TRD patients (83.33% vs. 55.88%, P < 0.001). In the BIA group, the time to PFC occurred earlier than that of the TRD group by an average of 3.66 days (P < 0.001). Additionally, the BIA group showed a lower postoperative 7-day CFB by an average of 6632.80 ml (P < 0.001) and fewer complications.

CONCLUSION

Among postinjury OA patients in the ICU, the use of BIA-guided fluid resuscitation resulted in a higher PFC rate and fewer severe complications than the traditional fluid resuscitation strategy.

Agreement of body weight of older adults measured on digital chair scale and mechanical platform scale

ABSTRACT Objective The aim of the study was to evaluate the agreement between the weight of older adults measured on a chair scale and a platform scale. Methods This is a cross-sectional study. We evaluated 131 older adults (?60 years old), walk-in patients, admitted to a university hospital. Weight was measured on a digital chair scale model MS5811 (Charder® brand) and after on a mechanical platform scale (Filizola® brand). For the agreement analysis, the intraclass correlation coefficient and the Bland-Altman plot were used. Results Most of the sample consisted of males individuals (57.3%; n= 75). The average age was 70.47±7.59 years (60-96 years old). Measured by both methods, weight showed normal distribution. The average weight measured was 67.99±14.03 kg on the chair scale and 68.04±14.02 kg on the platform scale. The intraclass correlation coefficient of weight measured by the two methods was 1.00 (IC95%=1.00-1.00; p<0.001). In the Bland-Altman plot, the mean bias for the weight measured on the chair scale and the platform scale was 0.049 (IC95%=-0.011 to 0.110; p=0.1084). Conclusions The agreement between the weight measured on a chair scale and on a platform scale was almost excellent. Thus, the chair scale can be used as an alternative method of measuring weight, especially in the older adults with postural instability, mobility restrictions or immobility syndrome.

Fluid balance monitoring in congestive heart failure patients in hospital: a best practice implementation project

OBJECTIVES

This aim of this project was to promote best practice in fluid balance monitoring in congestive heart failure patients.

INTRODUCTION

Fluid overload or pulmonary/vascular congestion is a common clinical feature in patients with heart failure and is associated with adverse outcomes. Maintaining records of patients' fluid intake and output (I&O) has long been considered an important aspect of nursing care to assess hydration status. In clinical practice, a prevalence of incongruence between I&O results and clinical signs and symptoms has been noted. We postulate that this incongruence may be due to an inaccurate or non-comprehensive collection of fluid I&O and/or patients' and their families' inadequate recognition of the importance of I&O recording.

METHODS

This implementation project was conducted in a cardiology ward of a medical hospital using the JBI Practical Application of Clinical Evidence System. Three audit criteria were utilized to represent best practice recommendations for fluid balance monitoring. A pre-implementation audit was conducted, followed by development of multiple interventions identified from a Getting Research into Practice analysis. Two post-implementation audits were conducted to determine the change in practice.

RESULTS

The post-implementation audit data demonstrated significantly improved outcomes across the measured best practice criteria. Specifically, improvement in compliance was noted in: i) fluid balance charts being utilized in conjunction with physical assessment and electrolyte monitoring to assess the hydration status of a patient (from 58% to 100% compliance); ii) patient involvement in more accurate documentation (from 42% to 75% compliance); and iii) staff education in fluid balance monitoring and documentation (from 53% to 100% compliance).

CONCLUSION

Fluid record omission was reduced at the completion of the project secondary to an increased awareness of the fluid record omission standards among patients as well as physical assessment and fluid overload correlation among the nursing staff in the unit. The findings demonstrate how audits can be utilized to promote best practice in health care. Additionally, the data indicate that focused education and the provision of relevant resources can have an immediate and positive impact on clinical practice.

Estimation of Body Fluid Status by Fluid Balance and Body Weight in Critically Ill Adult Patients: A Systematic Review

BACKGROUND

The charting of daily fluid balances and measurement of body weight changes are two noninvasive methods commonly used in the intensive care unit for estimating body fluid status. The determination of body fluid status plays an important role in the management of critically ill patients where aggressive fluid resuscitation is often required. This can adversely affect patient outcomes if changes in fluid distribution are not detected early in patients who are susceptible to fluid overload.

AIM

To synthesize the best available evidence on the accuracy of daily fluid balance charting compared with the measurement of body weight for the estimation of body fluid status in critically ill adult patients.

METHODS

The review considered studies that investigated the accuracy of charting daily fluid balances or changes in body weight measurements or used both noninvasive methods in the estimation of body fluid status. The search sought to identify published, English language studies from 1980 until February 2018. Databases searched included MEDLINE, CINAHL, EMBASE, TRIP, Scopus, TROVE, ProQuest Dissertations, Australian and New Zealand Trials Registry, and Cochrane Central Register of Clinical Trials. Three reviewers independently assessed retrieved studies that matched inclusion criteria using standardized critical appraisal instruments.

RESULTS

The review included 13 cohort studies. Effectiveness of daily fluid balance charting was affected by inaccuracies observed in seven studies. Inability to obtain consecutive daily body weight measurements reduced the accuracy of monitoring changes in five studies. Seven studies found measurement of daily fluid balance inconsistent with changes in body weight.

LINKING EVIDENCE TO ACTION

The accuracy of charting fluid balance is suspect. Measurement of body weight is hard to accomplish. A combination of the two commonly used methods is more likely to be effective in estimating body fluid status than reliance on one single approach.

Improving the accuracy of fluid intake charting through patient involvement in an adult surgical ward: a best practice implementation project

OBJECTIVES

The main objective of this evidence-based utilization project was to improve the accuracy of fluid intake charting through patient involvement.

INTRODUCTION

The accurate documentation and maintenance of fluid balance charts constitute an integral part of nursing care. However, inaccuracies in fluid balance charting by nurses often occur. Inaccurate charting can result in delayed interventions, affecting the safety of patients. It has been found that fluid intake charting in an acute surgical inpatient ward is highly inaccurate. Many expressions of dissatisfaction are evident among medical healthcare professionals and patients regarding the accurate updating of the charts. Therefore, evidence-based measures need to be implemented in order to improve the safety of patient care through accurate recording of patients' fluid intake.

METHODS

The project took place in a 21-bed acute surgical ward which had 30 patients. The Joanna Briggs Institute Practical Application of Clinical Evidence System (JBI-PACES) and Getting Research into Practice (GRiP) tools were used to implement the evidence-based project. A pre- and post- audit methodology congruent with the framework was applied. The project was implemented in three phases from April to September 2016. The audit criteria obtained from JBI-PACES were used. The project's primary focus was to harness patient involvement in improving the accuracy of fluid intake charting.

RESULTS

Criteria 1 and 2 revealed low levels of compliance during the pre-implementation audit, 3% and 10%, respectively. There were significant improvements one month post-implementation for both Criteria 1 and 2, 100% and 87%, also respectively. Fisher's exact test was carried out and the statistical significance of the results was achieved (p < 0.001), compared to the pre-implementation audit. At six months post-implementation, the audit found that both criteria were adequately sustained as a practice in the ward (Criterion 1: 100%, Criterion 2: 83%).

CONCLUSIONS

This project has demonstrated the effectiveness of improving the accuracy of fluid intake charting through patient involvement. The use of JBI-PACES and GRiP has allowed the effective utilization of evidence in practice. It has also provided evidence that effective engagement of the ground nurses and stakeholders coupled with the commitment of change champions and ground nurses can contribute to improving practice in a highly demanding acute care setting and lead to healthcare success.

Association Between Body Weight Variation and Survival and Other Adverse Events in Critically Ill Patients With Shock: A Multicenter Cohort Study of the OUTCOMEREA Network

OBJECTIVES

This study in critically ill patients with shock assessed the prognostic value of body weight variations occurring each day from day 3 to day 7 on the 30-day outcome in terms of mortality, occurrence of ventilator-associated pneumonia and of bedsore, and occurrence of length of stay.

DESIGN

Retrospective analysis of data. Multivariate subdistribution survival models were used at each day, from day 3 to day 7. The impact of body weight variations on length of stay was estimated through a multivariate negative binomial regression model.

SETTING

Prospective multicenter cohort study.

PATIENTS

Critically ill patients admitted in ICU with shock and requiring mechanical ventilation within 48 hours.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Two-thousand three-hundred seventy-four patients were included. Their median body weight variations increased from 0.4 kg (interquartile range, 0-4.8 kg) on day 3 to 3 kg (interquartile range, -0.4 to 8.2 kg) on day 7. Categories of body weight variations were defined depending on body weight variations interquartiles: weight loss, no weight gain, moderate and severe weight gain. A severe weight gain tended to be associated with death at days 5 and 6 (day 5: subdistribution hazard ratio, 1.27; 95% CI, 0.99-1.63; p = 0.06 and day 6: subdistribution hazard ratio, 1.43; 95% CI, 1.08-1.89; p = 0.01), a weight loss tended to be associated with bedsore, and a severe gain between at days 5 and 6 was associated with ventilator-associated pneumonia. Any body weight variations were associated with an increased length of stay.

CONCLUSIONS

In survivors at day 3, body weight variations during the first days of ICU stay might be a clinically relevant tool to prevent weight gain but also for prognostication of 30-day mortality, occurrence of ventilator-associated pneumonia, and occurrence of prolonged ICU stay.

Bio-electrical impedance analysis for perioperative fluid evaluation in open major abdominal surgery

Water retention and intercompartmental redistribution occur frequently in association with adverse postoperative outcomes, yet the available strategies for non-invasive assessment are limited. One such approach for evaluating body water composition in various circumstances is bio-electrical impedance analysis (BIA). This study aims to appraise the usefulness of the Body Composition Monitor (BCM, Fresenius Medical Care, Germany) in assessing body fluid composition and intercompartmental shifts before and after open major abdominal surgery. This prospective, clinician blinded observational study enrolled all the patients scheduled consecutively for elective major open abdominal surgery during a 1-year period starting from January 1st, 2016. BIA parameters—total body water (TBW), extracellular water (ECW), intracellular water (ICW), absolute fluid overload (AFO), and relative fluid overload (RFO) were measured before and after surgery. The results were compared with fluid balance and outcome parameters such as organ dysfunction, ICU-and hospital length of stay (-LOS). The study population included 71 patients aged 60.2 ± 12 of whom 60.6% men and with a BMI of 26.3 ± 5.1 kg/m². Postoperative acute kidney injury, respiratory dysfunction, and infections occurred in 14.0%, 19.7% and 28.1% of cases, respectively. The median LOS in ICU was 20 h and the hospital-LOS was 10 days. Positive intraoperative fluid balance (2.4 ± 1.0 L) resulted in a significant increase of TBW (1.4 ± 2.4 L) and of ECW (1.4 ± 1.2 L). Intraoperative fluid balance significantly correlated with TBW change (r = 0.23, p = 0.04) and with AFO change (r = 0.31, p < 0.01). A significant correlation was found between pre- and postoperative AFO and RFO on one hand, and ICU-LOS on the other. BIA may be a useful tool for the perioperative assessment of volume status.

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.

Recording patient bodyweight in hospitals: are we doing well enough?

Recording patient weight is a standard practice for all hospital admissions, with this measurement influencing other daily practices that rely on the delivery of safe and effective patient care. Patient weight is important in the areas of medication prescribing, fluid balance and assessment of nutrition. In particular, prescribing narrow therapeutic index medications may result in significant harm as a potential consequence of inaccurate dosing. Despite its importance, it is evident that bodyweight measurements are recorded in only 13.5-55% of hospital patients, in a variety of settings including the emergency department, intensive care unit, medical and surgical wards. Barriers to compliance of healthcare staff include additional workload, patient handling and availability of appropriate weighing equipment. Hospitals and patients would benefit from enhancing compliance with the systematic weighing of patients, staff training and removing barriers to performing this task.

Mortality in adult patients with fluid overload evaluated by BIVA upon admission to the emergency department

PURPOSE OF THE STUDY

The aim of this study was to investigate the association of fluid overload, measured by bioelectrical impedance vector analysis (BIVA) and also by accumulated fluid balance, with 30-day mortality rates in patients admitted to the emergency department (ED).

DESIGN

We conducted a prospective observational study of fluid overload using BIVA, taking measures using a multiple-frequency whole-body tetrapolar equipment. Accumulated fluid balances were obtained at 24, 48 and 72 hours from ED admission and its association with 30-day mortality.

PATIENTS

109 patients admitted to the ED classified as fluid overloaded by both methods.

RESULTS

According to BIVA, 71.6% (n=78) of patients had fluid overload on ED admission. These patients were older and had higher Sequential Organ Failure Assessment scores. During a median follow-up period of 30 days, 32.1% (n=25) of patients with fluid overload evaluated by BIVA died versus none with normovolaemia (p=0.001). There was no statistically significant difference in mortality between patients with and without fluid overload as assessed by accumulated fluid balance (p=0.81).

CONCLUSIONS

Fluid overload on admission evaluated by BIVA was significantly related to mortality in patients admitted to the ED.

Cumulative changes in weight but not fluid volume balances reflect fluid accumulation in ICU patients

BACKGROUND

The cumulative fluid balance of critically ill patients seems to be an outcome-relevant variable. However, there are no validated data for their reliability calculated for longer (> 5 days) periods of time.

METHODS

All ICU patients ≥ 18 years, with an ICU stay ≥ 5 days and a body weight ≤ 195 kg were evaluated from 1 January 2013 to 31 December 2013. Daily standardized weighing was performed using bed-integrated scales simultaneously with the daily 24-h fluid balance. Simultaneously, a fluid balance without and with insensible perspiration (10 ml/kg/day) was calculated for each 24 h. Primary endpoint: difference between cumulative fluid balance and body weight changes at the day of transfer to the normal ward or the day of death in the ICU, respectively, in each patient. All data are presented as medians with interquartile ranges (IQR) with 25 and 75 percentiles (IQR/25/75) unless otherwise noted.

RESULTS

One hundred and six critically ill patients were evaluated; 82 survivors and 24 nonsurvivors. Cumulative 24-h fluid balances rose continuously while body weight decreased over time. Correction of cumulative fluid balances for insensible perspiration (10 ml/kg/day) also did not match with body weight changes. Only survivors had a significant loss in body weight -1.8 (27.5/-6.1/1.0) kg.

CONCLUSIONS

Assuming that changes in body weight reflect changes in whole body water content cumulative daily fluid volume balances without or with correction for insensible water loss are not useful for estimating cumulative fluid balance of ICU patients. Survivors but not nonsurvivors had a significant loss of weight over time.

Impact of hyperhydration on the mortality risk in critically ill patients admitted in intensive care units: comparison between bioelectrical impedance vector analysis and cumulative fluid balance recording

BACKGROUND

Studies have demonstrated a positive correlation between fluid overload (FO) and adverse outcomes in critically ill patients. The present study aims at defining the impact of hyperhydration on the Intensive Care Unit (ICU) mortality risk, comparing Bioelectrical Impedance Vector Analysis (BIVA) assessment with cumulative fluid balance (CFB) recording.

METHODS

We performed a prospective, dual-centre, clinician-blinded, observational study of consecutive patients admitted to ICU with an expected length of ICU stay of at least 72 hours. During observational period (72-120 hours), CFB was recorded and cumulative FO was calculated. At the admission and daily during the observational period, BIVA was performed. We considered FO between 5% and 9.99% as moderate and a FO ≥ 10% as severe. According to BIVA hydration scale of lean body mass, patients were classified as normohydrated (>72.7%-74.3%), mild (>71%-72.7%), moderate (>69%-71%) and severe (≤ 69%) dehydrated and mild (>74.3%-81%), moderate (>81%-87%) and severe (>87%) hyperhydrated. Two multivariate logistic regression models were performed: the ICU mortality was the response variable, while the predictor variables were hyperhydration, measured by BIVA (BIVA model), and FO (FO model). A p-value <0.05 was considered to indicate statistical significance.

RESULTS

One hundred and twenty-five patients were enrolled (mean age 64.8 ± 16.0 years, 65.6% male). Five hundred and fifteen BIVA measurements were performed. The mean CFB recorded at the end of the observational period was 2.7 ± 4.1 L, while the maximum hydration of lean body mass estimated by BIVA was 83.67 ± 6.39%. Severe hyperhydration measured by BIVA was the only variable found to be significantly associated with ICU mortality (OR 22.91; 95% CI 2.38-220.07; p < 0.01).

CONCLUSIONS

The hydration status measured by BIVA seems to predict mortality risk in ICU patients better than the conventional method of fluid balance recording. Moreover, it appears to be safe, easy to use and adequate for bedside evaluation. Randomized clinical trials with an adequate sample size are needed to validate the diagnostic properties of BIVA in the goal-directed fluid management of critically ill patients in ICU.

Norepinephrine Dosing in Obese and Nonobese Patients With Septic Shock

BACKGROUND

Whether or not norepinephrine infusions for support of hemodynamic status in patients with septic shock should be weight based is unknown. This situation is particularly pertinent in patients who are extremely overweight or obese.

OBJECTIVE

To compare dosing requirements and effect of norepinephrine on blood pressure in obese and nonobese patients with septic shock.

METHODS

In a retrospective cohort study, data on adult patients with septic shock who received norepinephrine infusion for support of hemodynamic status in a tertiary care, academic medical center were analyzed. Patients were categorized as obese (body mass index ≥ 30) or nonobese (body mass index < 30). The primary outcome was dosing requirements of norepinephrine at 60 minutes after the start of the infusion. The secondary outcome was the log-transformed ratio of mean arterial pressure to norepinephrine.

RESULTS

The final cohort consisted of 100 obese and 100 nonobese patients. Mean norepinephrine infusion rate at 60 minutes was 0.09 (SD, 0.08) μg/kg per minute in the obese group and 0.13 (SD, 0.14) μg/kg per minute in the nonobese group (P = .006). The non-weight-based dose at 60 minutes was 9 μg/min in obese patients and 8 μg/min in nonobese patients (P = .72). The log transformed mean arterial pressure to norepinephrine ratio at 60 minutes was 2.5 (SD, 0.9) in obese patients and 2.5 (SD, 0.8) in nonobese patients (P = .54) CONCLUSIONS: Compared with nonobese patients, obese patients with septic shock require lower weight-based doses of norepinephrine and similar total norepinephrine doses.

Prognostic importance of weight change on short-term functional outcome in acute ischemic stroke

BACKGROUND

Controversy exists regarding the question of whether weight change decreases or increases the risk of mortality.

AIM

The aim of this study was to evaluate the prognostic importance of weight change on short-term outcomes in acute ischemic stroke patients.

METHODS

A total of 654 patients with acute ischemic stroke were enrolled in this study from March 2010 to May 2013. We assessed the weight change of each participant between admission and discharge from the Department of Neurology. Weight change was defined as change ≥0·05 kg/baseline body mass index unit. We evaluated the short-term outcomes using a modified Rankin Scale at three-months after the onset of a stroke.

RESULTS

Among the 654 patients, 35·2% were included in the weight-change group. Weight loss occurred in 24·6% of the participants during the hospital stay following the stroke, which lasted an average of nine-days. Compared with the weight-stable group, the pronounced weight-loss group had a higher risk of unfavorable outcomes (odds ratio 2·43; 95% confidence interval 1·12-5·25).

CONCLUSIONS

Short-term weight loss after stroke appears to be more common than we expected, and our results suggest that it is associated with unfavorable functional outcomes. Therefore, clinical nutrition should be considered as a component of medical treatment and weight loss should be monitored as an indicator of malnutrition.

Validity of exchangeable solute balance as a measure of blood volume in neurologically injured adults

BACKGROUND

Daily weight (DW) and examination of fluid balances (FB) are commonly used in assessments of extracellular fluid (ECF) and circulating blood volume (BV). We hypothesized that a calculated total body exchangeable solute, the main determinant of the ECF, would have high agreement and correlation with actual BV.

METHODS

The University of Washington IRB approved the study. We included a sample of consecutive adult patients in whom a BV was measured, while in the neuroscience intensive care units of a large academic medical center. BV was measured as part of routine care using iodinated (131)I albumin injection and the BVA-100 (Daxor Corp, New York, NY, USA). Total body exchangeable solute was estimated at the time of BV measurement by multiplying the calculated total body water by the sum of the sodium plus potassium and chloride measured in plasma. The correlation between the change in DW, FB (adjusted for insensible fluid loss), exchangeable solute, and BV was performed using linear regression with adjustment for number of days between admit and BV measurement, and capillary leak. Errors were computed using robust variance estimation.

RESULTS

55 patients had BV tests available, and 43 of them had subarachnoid hemorrhage. Total body exchangeable solute strongly correlated with BV (r = 0.75, 95% CI 0.63-0.84, p < 0.01 for Na(+)/K(+), and r = 0.71, 95% CI 0.58-0.81, p < 0.01 for Cl(-)). DW (r = 0.21) and FB (r = 0.11) were not correlated with BV.

CONCLUSIONS

Total body exchangeable solute appears to be a valid and reliable measure of BV and can be calculated using information readily available at the bedside. The value of having this information automatically calculated and available at the bedside should be explored.

Clinical Assessment of Fluid Balance is Incomplete for Colorectal Surgical Patients

Background and Aims:

Fluid balance for the surgical patient has been proven very important for the postoperative outcome and development of complications. The aim of this study was to evaluate, for the first time in modern times, the accordance between nurse-based fluid charting (cumulated fluid balance) and body weight change for general surgical patients.

Material and Methods:

This was a descriptive study with prospectively collected data from two clinical randomized multicenter trials. A total of 113 patients from American Society of Anesthesiology group I–III undergoing elective colorectal surgery were included. Cumulated fluid balance and body weight change were charted preoperatively and daily at the same time during a postoperative period of 6 days. Differences were calculated by subtracting cumulated fluid balance from body weight change (1 g = 1 mL), and agreement was assessed by making Bland–Altman plots as well as Pearson correlations.

Results:

From day 1 to 4, the mean difference between cumulated fluid balance and body weight change was below 0.4 kg/L. On day 5 and 6, the discrepancies increased with mean differences of, respectively, 1.2 kg/L (p < 0.002*) and 2 kg/L (p < 0.0001*). Bland–Altman plots showed increasingly poor agreement for all postoperative days with wide limits of agreement, ranging from more than 6 kg/L to almost 10 kg/L. Pearson correlations were moderate to strong at all times ranging from 0.437 (day 1) to 0.758 (day 4).

Conclusions:

The accordance between cumulated fluid balance and body weight change for colorectal surgical patients is relatively good for the first four postoperative days, however, with large uncertainty, whereas on the fifth and sixth postoperative day, the discrepancy is statistically and clinically significant. The fluid chart cannot stand alone in interpretation of the patient’s fluid balance; body weight and clinical judgment is indispensable.

Association between weight change and clinical outcomes in critically ill patients

PURPOSE

Body weight fluctuates daily throughout a patient's stay in the intensive care unit (ICU) due to a variety of factors, including fluid balance, nutritional status, type of acute illness, and presence of comorbidities. This study investigated the association between change in body weight and clinical outcomes in critically ill patients during short-term hospitalization in the ICU.

METHODS

All patients admitted to the Gyeongsang National University hospital between January 2010 and December 2011 who met the inclusion criteria of age 18 or above and ICU hospitalization for at least 2 days were prospectively enrolled in this study. Body weight was measured at admission and daily thereafter using a bed scale. Univariate and multivariate linear and logistic regression analyses were performed to evaluate factors associated with mortality and the association between changes in body weight and clinical outcomes, including duration of mechanical ventilation (MV) use, length of ICU stay, and ICU mortality.

RESULTS

Of the 140 patients examined, 33 died during ICU hospitalization, yielding an ICU mortality rate of 23.6%. Non-survivors experienced higher rates of severe sepsis and septic shock and greater weight gain than survivors on days 2, 3, 4, 5, and 6 of ICU hospitalization (P < .05). Increase of body weight on days 2 through 7 on ICU admission was correlated with the longer stay of ICU, and increase on days 3 through 7 on ICU admission was correlated with the prolonged use of mechanical ventilation. Increase of body weight on days 3 through 5 on ICU admission was associated with ICU mortality.

CONCLUSIONS

Increase in body weight of critically ill patients may be correlated with duration of mechanical ventilation use and longer stay of ICU hospitalization and be associated with ICU mortality.

Usefulness of the fluid balance: a randomised controlled trial in neonates

AIM

To assess the effects of fluid balance charts in neonates with moderate disease severity on duration of hospitalisation and medical interventions.

METHODS

Randomised, controlled trial in a neonatal ward in a general teaching hospital in the Netherlands between June 2009 and March 2010. One hundred seventy neonates with moderate disease severity, requiring continuous monitoring of vital parameters (mean gestational age 36(+2) weeks (standard deviation 2(+5) days), mean birthweight 2782 g (standard deviation 749 g)) participated. In the control group (n = 86), attending physicians could access all fluid balance data, whilst these data were blacked out in the intervention group (n = 84). Primary outcome was length of hospital stay. Secondary outcomes were percentage weight loss, interventions based on the fluid status, unblinding of fluid balance data and incident reporting.

RESULTS

Length of hospital stay did not differ significantly between the intervention and the control group (median 9 vs. 8 days, with ratio of geometric mean 1.25, 95% confidence interval 0.99 to 1.57; P = 0.06). We found no significant differences in secondary outcomes.

CONCLUSIONS

Routinely keeping fluid balances in neonates with moderate disease severity does not affect duration of hospitalisation or medical treatment.

Reliability of the fluid balance in neonates

AIM

To assess the reliability of fluid balance charts in neonates.

METHODS

An observational study in 170 nonbreastfed neonates, requiring continuous monitoring on a high-care unit, but not critically ill. The fluid balance was compared to daily body weight changes using Bland-Altman analysis. Differences more than 20% of daily fluid intake were considered clinically relevant.

RESULTS

The mean gestational age was 36 + 2 weeks (SD 18.7 days) and mean birth weight 2782 g (SD 749 g). The mean difference between 394 fluid balances over 24 h (in mL) and daily weight changes (in g) was -12.1 (limits of agreement -128.1 to 103.8). In 40% of comparisons, the difference with daily weight change was more than 20% of daily fluid intake.

CONCLUSION

Fluid balance charts both over- and underestimate body weight changes in an unpredictable pattern and are therefore unreliable as a single measure of fluid status in neonates.

Estimation of fluid status changes in critically ill patients: fluid balance chart or electronic bed weight?

PURPOSE

Monitoring of fluid balance (FB) can be achieved by subtracting recorded fluid output from input or by measuring changes in body weight (BW). The latter approach is difficult in the critically ill. Recently, hospital beds have become available with the ability to directly weigh patients in the intensive care unit (ICU) patients directly. We sought to compare FB estimates obtained by these 2 methods in a cohort of critically ill patients.

MATERIALS AND METHODS

Between November 2010 and May 2011, all patients admitted in our ICU for more than 2 consecutive days and nursed on a Hill-Rom (Batesville, Ind) Total Care bed were weighed daily at midnight hours. Fluids charting was done by electronic spreadsheet with automated 24 hours calculation. Differences in BW and FB between 2 consecutive days were compared using correlation and Bland-Altman analysis. Corrections for unmeasured fluids losses were performed using a predetermined formula based on peak temperature and intubation status.

RESULTS

We obtained complete data in 160 (31%) of 504 admissions exceeding 2 days (153 patients) resulting in 435 data points. The change in BW over 24 hours and FB for the same period was only weakly correlated before (r = 0.34; P < .001; Fig. 1) or after correction for insensible fluid losses (r = 0.34; P < .001). On Bland-Altman plot, the mean bias was small (0.07 kg), but the 95% limits of agreement, very large (-5.8 and 6.0 kg). The lack of agreement increased with the magnitude of the changes.

CONCLUSION

Obtaining daily weights in ICU patients proved difficult. Compliance was poor. The correlation between changes in BWs and FB was weak. Further studies are required to establish if accurate and reproducible daily weighing of ICU patients is feasible.

Weight-based determination of fluid overload status and mortality in pediatric intensive care unit patients requiring continuous renal replacement therapy

PURPOSE

In pediatric intensive care unit (PICU) patients, fluid overload (FO) at initiation of continuous renal replacement therapy (CRRT) has been reported to be an independent risk factor for mortality. Previous studies have calculated FO based on daily fluid balance during ICU admission, which is labor intensive and error prone. We hypothesized that a weight-based definition of FO at CRRT initiation would correlate with the fluid balance method and prove predictive of outcome.

METHODS

This is a retrospective single-center review of PICU patients requiring CRRT from July 2006 through February 2010 (n = 113). We compared the degree of FO at CRRT initiation using the standard fluid balance method versus methods based on patient weight changes assessed by both univariate and multivariate analyses.

RESULTS

The degree of fluid overload at CRRT initiation was significantly greater in nonsurvivors, irrespective of which method was used. The univariate odds ratio for PICU mortality per 1% increase in FO was 1.056 [95% confidence interval (CI) 1.025, 1.087] by the fluid balance method, 1.044 (95% CI 1.019, 1.069) by the weight-based method using PICU admission weight, and 1.045 (95% CI 1.022, 1.07) by the weight-based method using hospital admission weight. On multivariate analyses, all three methods approached significance in predicting PICU survival.

CONCLUSIONS

Our findings suggest that weight-based definitions of FO are useful in defining FO at CRRT initiation and are associated with increased mortality in a broad PICU patient population. This study provides evidence for a more practical weight-based definition of FO that can be used at the bedside.