Perioperative fluid and volume management: physiological basis, tools and strategies

Orthostatic intolerance after acute mild hypovolemia: incidence, pathophysiologic hemodynamics, and heart-rate variability analysis-a prospective observational cohort study

PURPOSE

Early postoperative mobilization can be hindered by orthostatic intolerance (OI). Postoperative OI has multifactorial pathogenesis, possibly involving both postoperative hypovolemia and autonomic dysfunction. We aimed to investigate the effect of mild acute blood loss from blood donation simulating postoperative hypovolemia, on both autonomic function and OI, thus eliminating confounding perioperative factors such as inflammation, residual anesthesia, pain, and opioids.

METHODS

This prospective observational cohort study included 26 blood donors. Continuous electrocardiogram data were collected during mobilization and night sleep, both before and after blood donation. A Valsalva maneuver and a standardized mobilization procedure were performed immediately before and after blood donation, during which cardiovascular and tissue oxygenation variables were continuously measured by LiDCOrapid™ and Massimo Root™, respectively. The incidence of OI, hemodynamic responses during mobilization and Valsalva maneuver, as well as heart rate variability (HRV) responses during mobilization and sleep were compared before and 15 min after blood donation.

RESULTS

Prior to blood donation, no donors experienced OI during mobilization. After blood donation, 6/26 (23%; 95% CI, 9 to 44) donors experienced at least one OI symptom. Three out of 26 donors (12%; 95% CI, 2 to 30) terminated the mobilization procedure prematurely because of severe OI symptoms. Cardiovascular and cerebral tissue oxygenation responses were reduced in patients with severe OI. After blood loss, HRV indices of total autonomic power remained unchanged but increased sympathetic and decreased parasympathetic outflow was observed during mobilization, but also during sleep, indicating a prolonged autonomic effect of hypovolemia.

CONCLUSION

We describe a specific hypovolemic component of postoperative OI, independent of postoperative autonomic dysfunction, inflammation, opioids, and pain.

STUDY REGISTRATION

ClinicalTrials.gov (NCT04499664); registered 5 August 2020.

Perioperative Fluid Management

The medical complexity of the geriatric patients has been steadily rising. Still, as outcomes of surgical procedures in the elderly are improving, centers are pushing boundaries. There is also a growing appreciation of the importance of perioperative fluid management on postoperative outcomes, especially in the elderly. Optimal fluid management in this cohort is challenging due to the combination of age-related physiological changes in organ function, increased comorbid burden, and larger fluid shifts during more complex surgical procedures. The current state-of-the-art approach to fluid management in the perioperative period is outlined.

Diuretic response to Ringer's solution is normal shortly after awakening from general anaesthesia: a retrospective kinetic analysis

Background

The elimination of Ringer's solution is severely depressed during general anaesthesia, but the degree to which this continues postoperatively is poorly established.

Methods

An intravenous infusion of Ringer's acetate solution 20 ml kg-1 was administered over 60 min in 12 patients undergoing laparoscopic cholecystectomy. Population kinetic analysis was performed based on repeated measurements of blood haemoglobin concentration and urinary excretion over 240 min regardless of when the operations were finished. The analysis contrasted the periods before and after awakening from general anaesthesia and compared them with data from 18 volunteers who received the same fluid at the same rate.

Results

Patients were monitored for approximately 2 h after awakening from general anaesthesia. The rate constant for redistribution of fluid from the extravascular space to the plasma (k21) and the rate constant for urinary excretion (k10) were significantly higher postoperatively than during the surgical period. Computer simulations indicated that urinary excretion after surgery was almost restored to the rate found in the volunteers. In contrast, the redistribution of fluid from the extravascular space to the plasma, which was almost nil during the surgery, showed only limited recovery during the postoperative phase, and was only approximately 10% of the flow rate found in the volunteers. The combination of nearly normalised urinary excretion and lack of adequate return of distributed fluid to the plasma promoted postoperative hypovolaemia.

Conclusion

The kinetic analysis indicates that plasma volume support should be given during the first 2 h after laparoscopic cholecystectomy.

Fluid and Hemodynamics

Several components of an Enhanced Recovery After Surgery (ERAS) pathway act to improve and simplify perioperative fluid and hemodynamic therapy. Modern perioperative fluid management has shifted away from the liberal fluid therapy and toward more individualized approaches. Clinical evidence has also emphasized the importance of maintaining adequate mean arterial pressure and avoiding intraoperative hypotension. Goal-directed hemodynamic therapy (GDHT), or the use of cardiac output monitoring to guide fluid and vasopressor use, has been shown to reduce complications, but its role within ERAS pathways is likely best-suited to high-risk patients or those undergoing high-risk procedures. This article reviews the mechanisms by which ERAS pathways aid the provider in hemodynamic management, reviews trends, and evidence regarding fluid and hemodynamic therapy approaches, and provides guidance on the practical implementation of these concepts within ERAS pathways.

DIFFERENT SURGICAL METHODS IN COLON ANASTOMOSIS: EXPERIMENTAL STUDY

Although many methods have been defined for colonic anastomosis, anastomotic leak still remains important for sepsis control and successful healing.

Intraoperative Red Blood Cell Transfusion Decision-making: A Systematic Review of Guidelines

OBJECTIVES

The objective of this work was to carry out a systematic review of clinical practice guidelines (CPGs) pertaining to intraoperative red blood cell (RBC) transfusions, in terms of indications, decision-making, and supporting evidence base.

SUMMARY OF BACKGROUND DATA

RBC transfusions are common during surgery and there is evidence of wide variability in practice.

METHODS

Major electronic databases (MEDLINE, EMBASE, and CINAHL), guideline clearinghouses and Google Scholar were systematically searched from inception to January 2019 for CPGs pertaining to indications for intraoperative RBC transfusion. Eligible guidelines were retrieved and their quality assessed using AGREE II. Relevant recommendations were abstracted and synthesized to allow for a comparison between guidelines.

RESULTS

Ten guidelines published between 1992 and 2018 provided indications for intraoperative transfusions. No guideline addressed intraoperative transfusion decision-making as its primary focus. Six guidelines provided criteria for transfusion based on hemoglobin (range 6.0-10.0 g/dL) or hematocrit (<30%) triggers. In the absence of objective transfusion rules, CPGs recommended considering other parameters such as blood loss (n = 7), signs of end organ ischemia (n = 5), and hemodynamics (n = 4). Evidence supporting intraoperative recommendations was extrapolated primarily from the nonoperative setting. There was wide variability in the quality of included guidelines based on AGREE II scores.

CONCLUSION

This review has identified several clinical practice guidelines providing recommendations for intraoperative transfusion. The existing guidelines were noted to be highly variable in their recommendations and to lack a sufficient evidence base from the intraoperative setting. This represents a major knowledge gap in the literature.

Routine Postoperative Chemistry Panels Are Not Necessary for Most Total Joint Arthroplasty Patients

BACKGROUND

The routine use of traditional chemistry-7 (chem-7) laboratory tests following total joint arthroplasty (TJA) has been called into question with the advent of short-stay procedures. Our objective was to determine the incidence, risk factors, and clinical interventions associated with inpatient abnormal routine postoperative chem-7 panels.

METHODS

From 2015 to 2017, 3,162 patients underwent a total of 3,721 TJA procedures, including primary total hip arthroplasty (THA) (n = 1,939; 52.1%) or primary total knee arthroplasty (TKA) (n = 1,782; 47.9%). Patients underwent routine preoperative and postoperative chem-7 testing. Clinical interventions were identified. With use of mixed-effects multivariate logistic regression, potential risk factors for abnormal chemistry panel values (including preoperative chem-7 results, type of surgery, age, sex, race, comorbidities, American Society of Anesthesiologists [ASA] score, and medications) were analyzed.

RESULTS

The rates of abnormal preoperative laboratory results were 3.4% for sodium (Na+), 7.4% for potassium (K+), 15.8% for blood urea nitrogen (BUN), and 26.4% for creatinine (Cr). The incidence of abnormal postoperative results was low for K+ (9.7%) and higher for Na+ (25.6%), BUN (55.6%), and Cr (27.9%). Preoperative abnormal laboratory results were a significant predictor of a postoperative abnormality for Na+ (odds ratio [OR] = 2.15; 95% confidence interval [CI] = 1.82 to 2.54), K+ (OR = 4.22; 95% CI = 3.03 to 5.88), and Cr (OR = 3.00; 95% CI = 2.45 to 3.68). Bilateral TJA was associated with increased odds of abnormal postoperative Na+ (OR = 1.56; 95% CI = 1.44 to 1.68). Renal disease was associated with increased odds of abnormal postoperative Cr (OR = 15.21; 95% CI = 5.67 to 40.77). Patients taking loop diuretics had increased odds of abnormal postoperative K+ (OR = 2.10; 95% CI = 1.42 to 3.11) and Cr (OR = 2.28; 95% CI = 1.56 to 3.33). Regarding intervention, 6.7% of hypokalemic patients received potassium chloride (KCl) fluid/tablets. Forty percent of hyponatremic patients received sodium chloride (NaCl) fluid/tablets. The electrolyte-related medicine consultation rate was 0.3% (13 of 3,721).

CONCLUSIONS

On the basis of our findings, we recommend postoperative chem-7 testing for patients with an abnormal preoperative laboratory result (Na+, K+, BUN, Cr), preexisting renal disease, bilateral TJA, and prescribed angiotensin-converting enzyme inhibitors (ACE), angiotensin II receptor blockers (ARB), and diuretics.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Preoperative carbohydrate loading and intraoperative goal-directed fluid therapy for elderly patients undergoing open gastrointestinal surgery: a prospective randomized controlled trial

Background

The effect of a combination of a goal-directed fluid protocol and preoperative carbohydrate loading on postoperative complications in elderly patients still remains unknown. Therefore, we designed this trial to evaluate the relative impact of preoperative carbohydrate loading and intraoperative goal-directed fluid therapy versus conventional fluid therapy (CFT) on clinical outcomes in elderly patients following gastrointestinal surgery.

Methods

This prospective randomized controlled trial with 120 patients over 65years undergoing gastrointestinal surgery were randomized into a CFT group (n=60) with traditional methods of fasting and water-deprivation, and a GDFT group (n=60) with carbohydrate (200ml) loading 2h before surgery. The CFT group underwent routine monitoring during surgery, however, the GDFT group was conducted by a Vigileo/FloTrac monitor with cardiac index (CI), stroke volume variation (SVV), and mean arterial pressure (MAP). For all patients, demographic data, intraoperative parameters and postoperative outcomes were recorded.

Results

Patients in the GDFT group received significantly less crystalloids fluid (1111442.9ml vs 1411412.6ml; p<0.001) and produced significantly less urine output (200ml [150300] vs 400ml [290500]; p<0.001) as compared to the CFT group. Moreover, GDFT was associated with a shorter average time to first flatus (5614.1h vs 6422.3h; p=0.002) and oral intake (7216.9h vs 8526.8h; p=0.011), as well as a reduction in the rate of postoperative complications (15 (25.0%) vs 29 (48.3%) patients; p=0.013). However, postoperative hospitalization or hospitalization expenses were similar between groups (p>0.05).

Conclusions

Focused on elderly patients undergoing open gastrointestinal surgery, we found perioperative fluid optimisation may be associated with improvement of bowel function and a lower incidence of postoperative complications.

Trial registration

ChiCTR, ChiCTR1800018227. Registered 6 September 2018 - Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01377-8.

Enhanced recovery pathway in adult patients undergoing thoracolumbar deformity surgery

BACKGROUND CONTEXT

Enhanced recovery (ERAS) pathways can help hospitals maximize the incentives of bundled payment models while maintaining high-quality patient care. A key component of an enhanced recovery pathway is the ability to predictably reduce inpatient length of stay, as this is a critical component of the cost equation.

PURPOSE

To determine the efficacy of an enhanced recovery pathway on reducing length of stay after thoracolumbar adult deformity surgery.

STUDY DESIGN

Single surgeon retrospective review of prospectively-collected data.

PATIENT SAMPLE

Forty adult deformity patients who underwent ≥5 levels of fusion to the pelvis (two to L5) with a single surgeon before and after implementation of an ERAS pathway.

METHODS

The pathway involved participation by anesthesiology, hospital medicine, and physical therapy, and was designed to achieve goals previously associated with decreased LOS (eg, EBL<1200 mL, procedure time <4.5 hours, avoidance of ICU postoperatively, and mobilization POD0-1). Patients were propensity-score matched 1:1 to a historical cohort (enhanced recovery [ER] and historical [H] cohorts), based on demographics, medical comorbidities, radiographic alignment parameters, and surgical factors. Outcomes were compared to determine the effect of the enhanced recovery pathway. Primary outcomes included LOS and 90-day complications and readmissions.

RESULTS

After matching, gender, BMI, ASA class, preoperative opioid dependence, day of surgery, sagittal alignment parameters, rate of revision surgery, three-column osteotomies, and interbody fusions were comparable between the cohorts (p>.05). In the ER cohort, there was reduced EBL (920±640 vs. 1437±555, p=.004) and no ER patient went to the ICU immediately following surgery, compared with 30% of H patients (p=.022). The ER cohort also had a greater number of patients ambulating by POD1 compared to the H cohort (100% vs. 55%, p=.010). ER patients had a shorter LOS (4.5±1.3 vs. 7.3±4.4 days, p=.010). A 90-day readmission and complications were comparable between the cohorts (p>.05).

CONCLUSIONS

The creation of an ERAS pathway for patients undergoing thoracolumbar adult deformity surgery reduced length of stay without negatively affecting short-term morbidity and complications. Given the specificity of this pathway to a single surgeon and hospital, the resources and staffing changes that were instrumental in creating the pathway may not be generalizable to other centers.

Fluid management: An update for perioperative practitioners

An interprofessional team approach is required to achieve optimum fluid balance for patients during the perioperative period. Incorrect management of fluid assessment and monitoring is associated with adverse outcomes. The scientific understanding of perioperative fluid balance has improved over recent years leading to changes in clinical practice with regard to volume and choice of intravenous fluid. It is important that perioperative practitioners have an understanding of intravenous fluid, fluid compartmentalisation, fluid mechanics and intravascular fluid control mechanisms. Optimum fluid status not only shortens hospital stay but also reduces the incidence of postoperative nausea and vomiting and complication profiles. This article aims to provide perioperative practitioners with a comprehensive overview of fluid management. It will cover important issues surrounding physiological control of fluid balance, choice of intravenous fluid therapy, methods to monitor intravascular volume and factors which influence delivery.

Preexisting right ventricular systolic dysfunction in high-risk patients undergoing non.emergent open abdominal surgery: A retrospective cohort study

Background:

The prognostic value of right ventricular systolic dysfunction in high-risk patients undergoing non-emergent open abdominal surgery is unknown. Here, we aim to evaluate whether presence of preexisting right ventricular systolic dysfunction in this surgical cohort is independently associated with higher incidence of postoperative major adverse cardiac events and all-cause in-hospital mortality.

Methods:

This is a single-centered retrospective study. Patients identified as American Society Anesthesiology Classification III and IV who had a preoperative echocardiogram within 1 year of undergoing non-emergent open abdominal surgery between January 2010 and May 2017 were included in the study. Incidence of postoperative major cardiac adverse events and all-cause in-hospital mortality were collected. Multivariable logistic regression was performed in a step-wise manner to identify independent association between preexisting right ventricular systolic dysfunction with outcomes of interest.

Results:

Preexisting right ventricular systolic dysfunction was not associated with postoperative major adverse cardiac events (P = 0.26). However, there was a strong association between preexisting right ventricular systolic dysfunction and all-cause in-hospital mortality (P = 0.00094). After multivariate analysis, preexisting right ventricular systolic dysfunction continued to be an independent risk factor for all-cause in-hospital mortality with an odds ratio of 18.9 (95% CI: 1.8-201.7; P = 0.015).

Conclusion:

In this retrospective study of high-risk patients undergoing non-emergent open abdominal surgery, preexisting right ventricular systolic dysfunction was found to have a strong association with all-cause in-hospital mortality.

A carbon monoxide 'single breath' method to measure total haemoglobin mass: a feasibility study

NEW FINDINGS

What is the central question of this study? Is it possible to modify the CO-rebreathing method to acquire reliable measurements of haemoglobin mass in ventilated patients? What is the main finding and its importance? A 'single breath' of CO with a subsequent 30 s breath hold provides almost as exact a measure of haemoglobin mass as the established optimized CO-rebreathing method when applied to healthy subjects. The modified method has now to be checked in ventilated patients before it can be used to quantify the contributions of blood loss and of dilution to the severity of anaemia.

ABSTRACT

Anaemia is defined by the concentration of haemoglobin (Hb). However, this value is dependent upon both the total circulating haemoglobin mass (tHb-mass) and the plasma volume (PV) - neither of which is routinely measured. Carbon monoxide (CO)-rebreathing methods have been successfully used to determine both PV and tHb-mass in various populations. However, these methods are not yet suitable for ventilated patients. This study aimed to modify the CO-rebreathing procedure such that a single inhalation of a CO bolus would enable its use in ventilated patients. Eleven healthy volunteers performed four CO-rebreathing tests in a randomized order, inhaling an identical CO volume. In two tests, CO was rebreathed for 2 min (optimized CO rebreathing; oCOR), and in the other two tests, a single inhalation of a CO bolus was conducted with a subsequent breath hold of 15 s (Proc_new 15s) or 30 s (Proc_new 30s). Subsequently, the CO volume in the exhaled air was continuously determined for 20 min. The amount of CO exhaled after 7 and 20 min was respectively 3.1 ± 0.3 and 5.9 ± 1.1 ml for oCOR, 8.7 ± 3.6 and 12.0 ± 4.4 ml for Proc_new 15s and 5.1 ± 2.0 and 8.4 ±2.6 ml for Proc_new 30s. tHb-mass was 843 ± 293 g determined by oCOR, 821 ± 288 g determined by Proc_new 15s (difference: P < 0.05) and 849 ± 311 g determined by Proc_new 30s. Bland-Altman plots demonstrated slightly lower tHb-mass values for Proc_new 15s compared with oCOR (-21.8 ± 15.3 g) and similar values for Proc_new 30s. In healthy volunteers, a single inhalation of a CO bolus, preferably followed by a 30 s breath hold, can be used to determine tHb-mass. These results must now be validated for ventilated patients.

ECG changes after non-cardiac surgery: a prospective observational study in intermediate-high risk patients

BACKGROUND

Efforts to mitigate the risk for perioperative cardiac events focus on both patient's and operation's risk and often include a preprocedural electrocardiogram (ECG). The merits of postprocedural ECG for detection of occult cardiac events occurring during surgery are unknown. We aim to explore the incidence of pre, and new postprocedural ECG pathologies in an intermediate-high risk population undergoing non-cardiac surgery.

METHODS

This single-center, prospective, observational study, included patients older than 18 years with at least two cardiovascular risk factors who were scheduled for non-cardiac surgery. All patients had pre, and postprocedural ECG. The ECG was analyzed and coded according to the Minnesota criteria. A multivariable logistic regression analysis was performed for indices associated with new postoperative ECG pathologies.

RESULTS

A total of 217 patients were enrolled. Preoperative pathologic ECG changes were recorded in 62.2% of the patients. Postoperatively, new ECG pathologies were documented in 49.8% of patients, most commonly T-wave changes (36.4% of changes). Pathologic ECG changes at baseline (OR 3.15, 95% CI [1.61-6.17]; P<0.01), diabetes (OR 1.93, 95% CI [1.02-3.64]; P=0.04), history of ischemic heart disease (OR 2.14, 95% CI [1.03-4.47]; P=0.04), higher volumes of fluid replacement (OR 1.70, 95% CI [1.10-2.61]; P=0.01) and higher levels of preoperative hemoglobin (OR 1.24, 95% CI [1.04-1.47]; P=0.01) were all independently associated with postoperative ECG changes.

CONCLUSIONS

Pre-, but most importantly, postoperative ECG changes are common in intermediate-high risk surgical patients. Postoperative ECG may be valuable to disclose silent cardiovascular events that occurred during surgery.

The Evaluation of Factors Affecting Hemodynamic Variability in Mechanically-Ventilated Patients After Cardiac Surgery

Background

Optimizing cardiac preload is usually the first step in patients with unstable hemodynamic. However, it should be remembered that an unnecessary volume expansion may exacerbate the hemodynamic. In mechanically ventilated patients, the ventilatory induced hemodynamic variations (VIHV) can be used to predict the fluid requirement. These variations (called dynamic indices of cardiac filling pressure), are superior to static indices (central venous and pulmonary artery occlusion pressure) in diagnosing any volume requirement. We theorized that some conditions other than hypovolemia might affect these hemodynamic variations.

Objectives

The current study aimed to discover these conditions in adult patients admitted to post-cardiac surgery ICU.

Methods

This antegrade cross-sectional study was conducted on 304 adult patients who were admitted to ICU after elective cardiac surgery in a teaching hospital (Tabriz-Iran). During the first 3 hours of the admission, the systolic (ΔSBP), diastolic (ΔDBP), mean (ΔMAP), and arterial blood pulse pressures (ΔPP) were invasively monitored and calculated in percent value. Because of the return of spontaneous breathing in most of the patients, the calculations were done only during the first 3-hour. All patients with spontaneous breathing, irregular cardiac rhythm, or re-admission to OR in this period were excluded from the study. We recorded demographic and surgical characteristics, perioperative hemodynamic and echocardiographic, and complications data and surveyed the correlation between VIHV and perioperative data.

Results

Two hundred and ninety two patients met the inclusion criteria. Coronary artery bypass grafting (CABG) was the most common surgery (64.4 %). Cardiopulmonary bypass (CPB) was used in 95.55% of the surgeries. In the first 24-hour, 51 patients required re-operation because of sternum closure, bleeding control, cardiac tamponade, and coronary artery revascularization. Mortality and morbidity occurred in 2 (0.68%) and 50 (17.12%) patients, respectively. Among VIHVs, the ΔPP had the most significant value. Thus, mean ΔPP was calculated and the correlation between its severity (≤ 20% vs. > 20%) and other values surveyed. It was high in patients with cardiac dysfunction and tamponade (P value < 0.001). No significant correlation was found between mean ΔPP severity and hemorrhage rate, fluid balance, need to vasoactive agents, blood products, or bleeding control, redo CABG or sternum closure surgery, time to tracheal extubation, ICU stay, and postoperative complications. Patients with closed sternum were the same as those with the unclosed sternum.

Conclusions

The ΔPP was the most sensitive VIHV parameter. Cardiac dysfunction and tamponade increased ΔPP. Unclosed sternum did not affect its value. ΔPP value did not affect postoperative complications rate, time to tracheal extubation, or ICU stay.

Goal-directed hemodynamic therapy versus restrictive normovolemic therapy in major open abdominal surgery: A randomized controlled trial

BACKGROUND

The aim of this study was to compare the occurrence of postoperative complications in patients undergoing elective open abdominal surgery and receiving intraoperative goal-directed hemodynamic therapy or restrictive normovolemic therapy.

METHODS

A total of 401 patients were randomized in the goal-directed hemodynamic therapy or restrictive normovolemic therapy groups. A cardiac output monitor was used in all goal-directed hemodynamic therapy patients and was left at the discretion of anesthetists in charge of patients in the restrictive normovolemic therapy group. The primary outcome was a composite morbidity endpoint (30-day mortality and complications grade 2-4 according to Dindo-Clavien classification). Secondary outcomes were the hospital duration of stay, the incidence of pulmonary, cardiovascular, and renal complications up to 30 days after surgery, and midterm survival.

RESULTS

Intraoperatively, the goal-directed hemodynamic therapy group received higher intravenous fluid volumes (mean of 10.8 mL/kg/h and standard deviation of 4.0) compared with the restrictive normovolemic therapy group (mean of 7.2 mL/kg/h and standard deviation of 2.0; P < .001). On the first postoperative day, similar fluid volumes were infused in the 2 groups. The primary outcome occurred in 57.7% of goal-directed hemodynamic therapy and 53.0% of restrictive normovolemic therapy (relative risk, 1.09 [95% confidence interval, 0.91-1.30]), and there was no significant difference between groups for any secondary outcomes.

CONCLUSION

Among patients undergoing major open abdominal surgery, the goal-directed hemodynamic therapy and the restrictive normovolemic therapy were associated with similar incidence of moderate-to-severe postoperative complications and hospital resource use.

Challenges to accomplish stringent fluid management standards 7 years after enhanced recovery after surgery implementation-The surgeon's perspective

BACKGROUND

This study aimed to analyze fluid management standards in 2 high-volume, enhanced recovery after surgery institutions 7 years after implementation.

METHODS

Retrospective analysis of consecutive patients undergoing elective, segmental colonic and extensive colorectal resections for benign and malignant pathology (2011-2017). Administration and composition of intravenous fluids, postoperative weight gain, and factors impeding compliance to preidentified fluid thresholds (3L fluid administration, 2.5 kg weight gain) were assessed. Multivariable logistic regression was performed to identify risk factors for postoperative adverse events.

RESULTS

A total of 5,155 patients were included. Among them, 2,320 patients (45.1%) received >3 L intravenous fluids at postoperative day 0. Fluid totals remained unchanged over the 7-year observation period. Fluid overload was independently associated with postoperative weight gain ≥2.5 kg at postoperative day 2 (odds ratio 1.34, P < .001). Patients with high American Society of Anesthesiologists score (≥3) undergoing open and longer (≥180 minutes) procedures were more likely to exceed both thresholds according to multivariable analysis (all P < .001). Other than open surgery, American Society of Anesthesiologists score ≥3, contamination class ≥3, and malignancy, both thresholds (≥3 L: odds ratio 1.76, 95% confidence interval 1.44-2.15, ≥ 2.5 kg: odds ratio 1.62, 95% confidence interval 1.33-1.97) were independent risk factors for postoperative adverse outcomes (occurring in 28.1% of patients).

CONCLUSION

Compliance with fluid thresholds appears to be challenging in patients with comorbidities undergoing open and long procedures. Efforts are encouraged because both thresholds are linked to adverse outcomes and appear to be potentially modifiable in selected patients.

Goal-Directed vs Traditional Approach to Intraoperative Fluid Therapy during Open Major Bowel Surgery: Is There a Difference?

Introduction

Optimum perioperative fluid therapy is important to improve the outcome of the surgical patient. This study prospectively compared goal-directed intraoperative fluid therapy with traditional fluid therapy in general surgical patients undergoing open major bowel surgery.

Methodology

Patients between 20 and 70 years of age, either gender, ASA I and II, and scheduled for elective open major bowel surgery were included in the study. Patients who underwent laparoscopic and other surgeries were excluded. After routine induction of general anaesthesia, the patients were randomised to either the control group (traditional fluid therapy), the FloTrac group (based on stroke volume variation), or the PVI group (based on pleth variability index). Fluid input and output, recovery characteristics, and complications were noted.

Results

306 patients, with 102 in each group, were enrolled. Five patients (control (1), FloTrac (2), and PVI (2)) were inoperable and were excluded. Demographic data, ASA PS, anaesthetic technique, duration of surgery, and surgical procedures were comparable. The control group received significantly more crystalloids (3200 ml) than the FloTrac (2000 ml) and PVI groups (1875 ml), whereas infusion of colloids was higher in the FloTrac (400–700 ml) and PVI (200–500 ml) groups than in the control group (0–500 ml). The control group had significantly positive net fluid balance intraoperatively (2500 ml, 9 ml/kg/h) compared to the FloTrac (1515 ml, 5.4 ml/kg/h) and PVI (1420 ml, 6 ml/kg/h) groups. Days to ICU stay, HDU stay, return of bowel movement, oral intake, morbidity, duration of hospital stay, and survival rate were comparable. The total number of complications was not different between the three groups. Anastomotic leaks occurred more often in the Control group than in the others, but the numbers were small.

Conclusions

Use of goal-directed fluid management, either with FloTrac or pleth variability index results in a lower volume infusion and lower net fluid balance. However, the complication rate is similar to that of traditional fluid therapy. This trial is registered with CTRI/2018/04/013016.

Non-Invasive Venous waveform Analysis (NIVA) for monitoring blood loss in human blood donors and validation in a porcine hemorrhage model

STUDY OBJECTIVE

There is an unmet need for a non-invasive approach to diagnose hemorrhage early, before changes in vital signs occur. Non-Invasive Venous waveform Analysis (NIVA) uses a unique physiological signal (the peripheral venous waveform) to assess intravascular volume. We hypothesized changes in the venous waveform would be observed with blood loss in healthy adult blood donors and characterized hemorrhage using invasive monitoring in a porcine model.

DESIGN

Prospective observational study.

SETTING

American Red Cross donation center.

PATIENTS

50 human blood donors and 12 non-donating controls; 7 Yorkshire pigs.

INTERVENTIONS

A venous waveform capturing prototype (NIVA device) was secured to the volar aspect of the wrist in human subjects. A central venous catheter was used to obtain hemodynamic indices and venous waveforms were obtained using the prototype NIVA device over the saphenous vein during 400 mL of graded hemorrhage in a porcine model.

MEASUREMENTS

Venous waveforms were transformed from the time to the frequency domain. The ratiometric power contributions of the cardiac frequencies were used to calculate a NIVA value representative of volume status.

MAIN RESULTS

A significant decrease in NIVA value was observed after 500 mL of whole blood donation (p < .05). A ROC curve for the ability of the NIVA to detect 500 mL of blood loss demonstrated an area under the curve (AUC) of 0.94. In the porcine model, change in NIVA value correlated linearly with blood loss and with changes in hemodynamic indices.

CONCLUSIONS

This study provides proof-of-concept for a potential application of NIVA in detection of blood loss. NIVA represents a novel physiologic signal for detection of early blood loss that may be useful in early triage and perioperative management.

Perioperative blood loss: estimation of blood volume loss or haemoglobin mass loss?

BACKGROUND

Perioperative blood loss is an essential parameter in research into Patient Blood Management. However, currently there is no "gold standard" method to quantify it. Direct measurements of blood loss are considered unreliable methods, and the formulae to estimate it have proven to be significantly inaccurate. Given the need for better research tools, this study evaluated an estimation of haemoglobin mass loss as an alternative approach to estimate perioperative blood loss, and compared it to estimations based on blood volume loss.

MATERIAL AND METHODS

We studied one hundred consecutive patients undergoing urological laparoscopic surgery. Both haemoglobin mass loss and blood volume loss were directly measured during surgery, under highly controlled conditions for a reliable direct measurement of blood loss. Three formulae were studied: 1) a haemoglobin mass loss formula, which estimated blood loss in terms of haemoglobin mass loss, 2) the López-Picado's formula and 3) an empirical volume formula that estimated blood loss in terms of blood volume loss. The empirical volume formula was developed within the study with the aim of providing the best possible estimation of blood volume loss in the studied population. The formulae were evaluated and compared by assessing their agreements with their respective direct measurements of blood loss.

RESULTS

The haemoglobin mass loss formula met the predefined agreement criterion of ±71 g, with 95% limits of agreement ranging from 0.6 to 44.1 g and a moderate overestimation of 22.4. In comparison to both blood volume loss formulae, the haemoglobin mass loss formula was superior in every agreement parameter evaluated.

DISCUSSION

In this study, the estimation of haemoglobin mass loss was found to be a more accurate method to estimate perioperative blood loss. This estimation method could be a robust research tool, although more studies are needed to establish its reliability.

[Anesthesia for renal transplantation in patients with dilated cardiomyopathy: a retrospective study of 31 cases]

BACKGROUND AND OBJECTIVES

Dilated cardiomyopathy is a state of progressive enlargement of cardiac chambers mainly left ventricle which leads to decreased cardiac output and ultimately cardiac failure. Although it has multifactorial etiology, it is quite common in patients with end stage renal disease who require renal transplant surgery for their cure. Both conditions go side by side and anesthetic management of such cases poses real challenge to anesthesiologist. Strict monitoring and control of cardiac physiology is of utmost importance besides meticulous fluid management, thus preserving renal blood flow on one hand and preventing cardiac failure on other hand. This is the basis of achieving good outcome of the renal transplant surgery.

METHODS

This is a retrospective observational study done by analysing electronic database of 31 patients with dilated cardiomyopathy who underwent renal transplant surgery. Data was studied in terms of demographics, duration of renal disease, comorbidities mainly hypertension, cardiac echo graphic findings including ejection fraction, medications and post-operative outcome.

RESULTS

Most common perioperative complication in this patient population was hypotension (51.61%) followed by pulmonary complications postoperative mechanical ventilation (12.9%) and pulmonary edema (6.45%). High incidence of hypotension may be a causative factor to increased rate of delayed graft functioning (12.9%) and acute tubular necrosis (2.23%) in these patients.

CONCLUSION

Strict monitoring and control of hemodynamic parameters as well as meticulous fluid therapy is the cornerstone in improving outcome in patients with dilated cardiomyopathy undergoing renal transplant surgery.

Effects of the Folk Medicinal Plant Extract Ankaferd BloodStopper on the Healing of Colon Anastomosis: An Experimental Study in a Rat Model

Objectives:

Ankaferd BloodStopper (ABS) is a topical hemostatic agent that modulates the inflammatory response and accelerates wound healing. The aim of this study was to determine the effects of ABS on the colon anastomosis wound healing in a rat model.

Methods:

Thirty-two Wistar albino rats were divided into four groups as follows: Group A (n=8), left colonic anastomosis plus ABS treatment (sacrificed on the 3^rd day); Group B (n=8) (control), left colonic anastomosis (sacrificed on the 3^rd day); Group C (n=8), left colonic anastomosis plus ABS treatment (sacrificed on the 7^th day); and Group D (n=8) (control), left colonic anastomosis (sacrificed on the 7^th day). All rats were sacrificed at the end of the experiment to assess the anastomosis integrity and the presence of perianastomosis abscesses, peritonitis, and adhesions. Additionally, the bursting pressure and hydroxyproline (OH-pyroline) levels were determined, and a histopathologic evaluation of the perianastomosis tissue was conducted.

Results:

The mean bursting pressure on Day 7 was significantly higher than that on Day 3 in the ABS group (p=0.017). Overall, the bursting pressure was higher in animals treated with ABS than in the control animals, although the difference was not statistically significant. The OH-pyroline levels of both ABS groups were significantly higher than in the control groups. The mean OH-pyroline level on Day 7 was higher than that on Day 3 in the ABS-treated animals (p=0.038).

Conclusion:

ABS increases collagen formation and neovascularization, and it has a positive impact during the colon anastomosis healing in an experimental model of wound healing.

Vancomycin-Associated Acute Kidney Injury in Critically Ill Adolescent and Young Adult Patients

BACKGROUND

Risk factors for the development of vancomycin-associated acute kidney injury (AKI) have been evaluated in both pediatric and adult populations; however, no previous studies exist evaluating this in the critically ill adolescent and young adult patients.

OBJECTIVE

Identify the incidence of AKI and examine risk factors for the development of AKI in critically ill adolescents and young adults on vancomycin.

METHODS

This retrospective review evaluated the incidence of AKI in patients 15 to 25 years of age who received vancomycin, while admitted to an intensive care unit. Acute kidney injury in this population was defined as an increase in serum creatinine by 0.5 mg/dL or 50% from baseline. Patients who developed AKI were evaluated for specific risk factors compared to those who did not develop AKI.

RESULTS

A total of 50 patients (20 developed AKI) were included in the study. There was no difference in vancomycin daily dose or duration of vancomycin therapy. Maximum vancomycin trough (31.15 mg/dL vs 12.5 mg/dL, P = .006), percentage of patients with concurrent nephrotoxic medication (95% vs 60%, P = .012) and concurrent vasopressor (55% vs 23%, P = .029) were higher in those who developed AKI. Percentage of patients who underwent a procedure while on vancomycin (35% vs 6.7%, P = .021) was also higher within the AKI group.

CONCLUSIONS

Vancomycin-associated AKI occurred in 40% of critically ill adolescent and young adult patients. These patients may be more likely to develop vancomycin-associated AKI if they had undergone a procedure, as well as in the presence of high vancomycin trough levels, concurrent nephrotoxic agents, and concurrent vasopressor therapy.

Receiver operating characteristic analysis to determine optimal fluid management during open colorectal surgery

AIM

The present study aimed to analyse fluid management and to define optimal fluid-related thresholds for elective open colorectal surgery.

METHOD

A retrospective analysis was made of all consecutive elective open colorectal resections performed in our tertiary centre between May 2011 and May 2017. The main outcomes were postoperative complications [overall (I-V) and severe (IIIB-V) according to the Clavien classification], respiratory complications and postoperative ileus (POI). Critical thresholds regarding perioperative fluid management and postoperative weight gain were identified by using receiver operator characteristic (ROC) analysis. Independent risk factors for overall complications were identified by multivariable logistic regression analysis.

RESULTS

Of 121 patients who had open operations, 84 (69%) had some complication and 26 (21%) had severe complications. Respiratory complications and POI occurred in 15 (12%) and 46 patients (38%), respectively. The thresholds for intravenous fluids were 3.5 l at postoperative day (POD) 0 [area under ROC curve (AUROC) 0.7 for any 0.69 for respiratory complications] and 3.5 kg weight gain at POD 2 (AUROC 0.82 for respiratory complications). Multivariable analysis revealed weight gain of > 3.5 kg at POD 2 (OR 5.9; 95% CI 1.3-16.6) as a significant risk factor for overall complications. Acute kidney injury was observed in five patients (4%), three (5%) in the group with > 3.5 l at POD 0 and two (3%) in the group with < 3.5 l at POD 0 (P = 0.64). Creatinine increase was transitory and all patients regained baseline levels before discharge.

CONCLUSION

A weight gain of > 3.5 kg at POD 2 has been identified as the critical threshold for overall and respiratory complications and prolonged length of stay after open elective colorectal surgery.

Goal-directed fluid therapy based on noninvasive cardiac output monitor reduces postoperative complications in elderly patients after gastrointestinal surgery: A randomized controlled trial

Objective:

Goal-directed fluid therapy (GDFT) was associated with improved outcomes after surgery. Noninvasive Cardiac Output Monitoring (NICOM) has proved to be a good choice for guiding GDFT. This study evaluated the effect of GDFT based on NICOM on prognosis in elderly patients undergoing resection of gastrointestinal tumor.

Methods:

Fifty patients scheduled for elective laparoscopic radical resection for stomach, colon or rectal cancer in Yongchuan Hospital of Chongqing Medical University between November 2014 and December 2015 were included and randomly divided into two groups: conventional fluid therapy (group C, n=25) and goal-directed fluid therapy (group G, n=25). The primary outcome was moderate or severe postoperative complications within 30 days.

Results:

Finally, 45 patients successfully completed the study (group G, n=22; group C, n=23). There were no difference of the duration of surgery, the requirement of vasoactive agents and the bleeding volume between two groups (P>0.05). Total fluids infused were 2956±629 ml (group C) and 2259±454 ml (group G) (P<0.05), while the requirement of colloid was increased in group G (1103±285ml vs 855±226ml) (P<0.05). The MAP and the mean CI were higher in group G (P<0.05). Compared with group C, the time when the patients passed the flatus and the length of hospital stay after operation were shortened in group G (12.6±2.4day vs17.2±2.6day), the incidence of postoperative complications were significantly lower in group G (P<0.05).

Conclusions:

Goal-directed fluid therapy based on NICOM was significantly associated with improvement of prognosis in elderly patients undergoing resection of gastrointestinal tumor which reduced postoperative complications.

Has Tranexamic Acid in Total Knee Arthroplasty Made Tourniquet Use Obsolete?

The application of tranexamic acid (TXA) in total joint arthroplasty has dramatically improved peri-operative blood management. In light of these benefits, a study by Huang et al., "Intravenous and Topical Tranexamic Acid Alone Are Superior to Tourniquet Use for Primary Total Knee Arthroplasty," evaluates the need for continued use of the intra-operative tourniquet, which remains a routine practice with documented benefits and adverse effects. This review evaluates the study's design and critically interprets its findings for clinical practice. Through a prospective, randomized trial, Huang et al. demonstrated that among selected patients undergoing primary total knee arthroplasty, the use of a tourniquet results in no reduction in blood loss beyond that provided by TXA alone. Moreover, the use of TXA without a tourniquet led to improved early clinical outcomes such as reduced post-operative swelling, improved knee range of motion at discharge, and enhanced patient satisfaction. As medicine is practiced in an increasingly value-driven environment, this study provides a useful method for evaluating the utility of commonly used interventions. Its findings highlight the need for future investigations into the optimal administration of TXA in total knee arthroplasty.

Prevention of acute kidney injury through accurate fluid balance monitoring

Acute kidney injury (AKI) is associated with increased patient morbidity, mortality and an extended hospital stay. The financial burden to the National Health Service is high and it can affect up to one in five inpatients. Optimal fluid balance management is essential for the prevention of AKI and this can be particularly challenging in the patient with trauma. Our aim was to reduce the rate of AKI in patients with traumatic injuries in the regional trauma centre. We developed new fluid balance charts and documented how well these were completed. The number of AKI alerts per month was calculated on our pathology system. Scenario training was delivered at handover meetings and an e-learning tool was designed at three levels: healthcare assistants; nurses; and medical staff, dietetics and pharmacists. Educational posters were placed in clinical areas and patient information leaflets produced. Junior doctors were regularly informed of AKI rates on the ward. The number of AKI alerts on our trauma ward declined from 50 in January 2016 to 19 in November 2016. The mean monthly rate of AKI fell 33% following the invention (P<0.001). Completion of fluid balance charts improved; 6 hourly urine output documentation increased from 36% to 68% and running 1 hourly output increased from 80% to 96%. Calculation of total daily fluid balance rose from 12% to 72%, before decreasing to 32%. This highlighted the need for continued encouragement. Improved fluid balance monitoring led to a reduction in the prevalence of AKI in patients admitted to this trauma centre.

Endothelial Glycocalyx and Cardiopulmonary Bypass

On the outer surface of a human cell there is a dense layer of complex carbohydrates called glycocalyx, also referred to as glycans or the sugar coating on the cell surface, which is composed of a complex array of oligosaccharide and polysaccharide glucose chains that are covalently bonded to proteoglycans and lipids bound to the cell membrane surface. Studies of an intact endothelial glycocalyx layer (EGL) have revealed a number of critical functions that relate the importance of this protective layer to vascular integrity and permeability. These functions include the following: stabilization and maintenance of the vascular endothelium, an active reservoir of essential plasma proteins (i.e., albumin, antithrombin, heparan sulfate, and antioxidants), a buffer zone between the blood (formed elements) and the surface of the endothelium, and a mechanotransducer to detect changes in shear stress that facilitate vascular tone. There have been numerous review articles about the structure and function of endothelial glycocalyx over the past two decades, yet there still remains a significant knowledge gap in the perfusion literature around the importance of EGL. Perioperative fluid management and gaseous microemboli can both contribute to the damage/degradation of endothelial glycocalyx. A damaged EGL can result in systemic and myocardial edema, platelet and leukocyte adhesion, fluid extravasation, and contributes to microvascular perfusion heterogeneity. Knowledge of the importance of endothelial glycocalyx will enable clinicians to have a better understanding of the impact of gaseous microbubbles, hyperoxia, and ischemic reperfusion injury during cardiac surgery. The purpose of this article is to provide an in depth review of the EGL and how this protective barrier impacts the microcirculation, fluid homeostasis, inflammation, and edema during cardiac surgery.

Determination of Perioperative Blood Loss: Accuracy or Approximation?

BACKGROUND

Various different interventions can be used to reduce surgical blood loss; however, there is no "gold standard" for accurately measuring the volume of perioperative blood loss, and this makes it difficult to assess the efficacy of these interventions.

METHODS

We used data from a previous multicenter double-blind randomized clinical trial in patients undergoing total hip arthroplasty in which we compared 2 regimens for administering tranexamic acid versus placebo. We assessed direct measures (external blood loss) and indirect estimates (using the formulas of Bourke, Gross, Mercuriali, and Camarasa and a new formula we have developed) using analysis of variance to compare estimated volumes of blood loss among the study groups. In addition, intraclass correlation coefficients (ICCs) and Bland-Altman diagrams were used to compare the estimated volumes of blood loss obtained with each formula.

RESULTS

The mean estimated external blood loss was 909 ± 324 mL, and the mean estimates of blood loss calculated using the formulas of Gross, Bourke and Smith, and Camarasa were 1308 ± 555, 1091 ± 454, and 1641 ± 945 mL, respectively, whereas we obtained a value of 1511 ± 919 mL with the new formula at day 2. In all cases, the results favored the use of tranexamic acid (P < .0001). Comparing results of the new and other formulas, we found moderate-to-low agreement (in terms of ICCs) except for that of Camarasa (ICC: 0.992). The limits of agreement with the new formula ranged from -378 to 93 in the case of the comparison with Camarasa's formula and from -2226 to 959 for external blood loss, the difference depending on the magnitude of the estimate to a large extent.

CONCLUSIONS

Formulas that take into account both anthropometric and laboratory parameters are useful for evaluating the efficacy of interventions aiming to decrease blood loss but do not ensure that the values obtained are sufficiently accurate for absolute measuring.

Strategies for Intravenous Fluid Resuscitation in Trauma Patients

Intravenous fluid management of trauma patients is fraught with complex decisions that are often complicated by coagulopathy and blood loss. This review discusses the fluid management in trauma patients from the perspective of the developing world. In addition, the article describes an approach to specific circumstances in trauma fluid decision-making and provides recommendations for the resource-limited environment.

The Ongoing Controversy: Crystalloids Versus Colloids

There is still much debate over the optimal fluid to use for resuscitation. Different studies have indicated either crystalloid or colloid is the ideal intravenous solution to administer, based on mortality or various physiological parameters. Older studies found differences between crystalloids and colloids. However, with the evolving science of fluid administration, more recent studies have shown no differences in patient outcomes. This review article will provide an overview of these substances and discuss the advantages, disadvantages, and implications for giving crystalloids and colloids in clinical practice.

Systemic inflammatory response during cardiac surgery: a pilot study

OBJECTIVE

There is a growing body of evidence indicating that perioperative fluid management during cardiac surgery influences patient care and outcome. The choice of fluid therapy and the degree of systemic inflammatory response triggered during surgery control the effects of tissue edema formation and end-organ function. As such, "goal-directed" fluid resuscitation protocols that measure colloid osmotic pressure (COP) may promote improvements in patient morbidity and mortality.

METHODS

Thirty patients scheduled for primary coronary artery bypass grafting were prospectively randomized for perioperative fluid treatment under COP guidance [albumin (ALB), n = 17] or conventional fluid protocols without COP support (control, n = 13). Whole-blood samples were drawn at four different time intervals including (A) anesthesia induction, (B) 10 minutes after the initiation of cardiopulmonary bypass, (C) at the completion of sternal skin approximation, and (D) 3 hours after admission to the cardiac intensive care unit. Interleukin 6 (IL-6) and IL-8 were measured by immunometric, enzyme-linked immunosorbent assays as well as C-reactive protein. Colloid osmotic pressure values were measured using a colloid osmometer.

RESULTS

As compared with conventional fluid protocols, the patients treated in the intervention (ALB) group received significantly less total perioperative fluid [7893.6 (1874.5) vs 10,754.8 (2403.9), P = 0.001], and this relationship remained after controlling for age, sex, and The Society of Thoracic Surgeons risk score (β = -0.5, t = -3.1, P = 0.005). Colloid osmotic pressure values were significantly higher in the ALB group at time point D after surgery (P = 0.03). There were no significant differences in IL-6, IL-8, and C-reactive protein values between the groups at any of the time blood draw intervals. Perioperative outcomes were evaluated by treatment group. For both groups, the incidence of perioperative morbidity was low and did not differ by treatment group.

CONCLUSIONS

The use of COP-guided fluid resuscitation was associated with a significant reduction in perioperative fluid demand. However, patients prescribed to COP-guided fluid therapy did not experience a reduction in whole-body inflammation or improved surgical outcome as compared with conventional fluid management techniques.

Effects of administration of a synthetic low molecular weight/low molar substitution hydroxyethyl starch solution in healthy neonatal foals

This study compared the effects of IV administration of isotonic fluid therapy and colloidal fluid therapy in healthy neonatal foals. Fifteen healthy neonatal foals were used in a randomized blinded prospective clinical study. Foals were randomly assigned to receive a bolus of 20 mL/kg of tetrastarch (TES) or balanced crystalloid solution. Vital parameters, colloid osmotic pressure (COP), and various clinicopathologic variables were assessed prior to infusion and at various time points up to 120 h after infusion. The treatment group (TES) had a significant increase in both COP and percentage increase in COP at 1 and 3 h. The COP was significantly lower than baseline at 3 h in the control group. No significant changes were observed in coagulation parameters in either group. Tetrastarch was effective in increasing COP for 3 h after infusion and had no notable adverse clinical effects in this group of healthy foals. Further studies are warranted regarding optimal dosing and effects in clinically ill foals.

Postoperative fluid management

Postoperative care units are run by an anesthesiologist or a surgeon, or a team formed of both. Management of postoperative fluid therapy should be done considering both patients’ status and intraoperative events. Types of the fluids, amount of the fluid given and timing of the administration are the main topics that determine the fluid management strategy. The main goal of fluid resuscitation is to provide adequate tissue perfusion without harming the patient. The endothelial glycocalyx dysfunction and fluid shift to extracellular compartment should be considered wisely. Fluid management must be done based on patient’s body fluid status. Patients who are responsive to fluids can benefit from fluid resuscitation, whereas patients who are not fluid responsive are more likely to suffer complications of over-hydration. Therefore, common use of central venous pressure measurement, which is proved to be inefficient to predict fluid responsiveness, should be avoided. Goal directed strategy is the most rational approach to assess the patient and maintain optimum fluid balance. However, accessible and applicable monitoring tools for determining patient’s actual fluid need should be further studied and universalized. The debate around colloids and crystalloids should also be considered with goal directed therapies. Advantages and disadvantages of each solution must be evaluated with the patient’s specific condition.

Fluid balance, intradialytic hypotension, and outcomes in critically ill patients undergoing renal replacement therapy: a cohort study

Introduction

In this cohort study, we explored the relationship between fluid balance, intradialytic hypotension and outcomes in critically ill patients with acute kidney injury (AKI) who received renal replacement therapy (RRT).

Methods

We analysed prospectively collected registry data on patients older than 16 years who received RRT for at least two days in an intensive care unit at two university-affiliated hospitals. We used multivariable logistic regression to determine the relationship between mean daily fluid balance and intradialytic hypotension, both over seven days following RRT initiation, and the outcomes of hospital mortality and RRT dependence in survivors.

Results

In total, 492 patients were included (299 male (60.8%), mean (standard deviation (SD)) age 62.9 (16.3) years); 251 (51.0%) died in hospital. Independent risk factors for mortality were mean daily fluid balance (odds ratio (OR) 1.36 per 1000 mL positive (95% confidence interval (CI) 1.18 to 1.57), intradialytic hypotension (OR 1.14 per 10% increase in days with intradialytic hypotension (95% CI 1.06 to 1.23)), age (OR 1.15 per five-year increase (95% CI 1.07 to 1.25)), maximum sequential organ failure assessment score on days 1 to 7 (OR 1.21 (95% CI 1.13 to 1.29)), and Charlson comorbidity index (OR 1.28 (95% CI 1.14 to 1.44)); higher baseline creatinine (OR 0.98 per 10 μmol/L (95% CI 0.97 to 0.996)) was associated with lower risk of death. Of 241 hospital survivors, 61 (25.3%) were RRT dependent at discharge. The only independent risk factor for RRT dependence was pre-existing heart failure (OR 3.13 (95% CI 1.46 to 6.74)). Neither mean daily fluid balance nor intradialytic hypotension was associated with RRT dependence in survivors. Associations between these exposures and mortality were similar in sensitivity analyses accounting for immortal time bias and dichotomising mean daily fluid balance as positive or negative. In the subgroup of patients with data on pre-RRT fluid balance, fluid overload at RRT initiation did not modify the association of mean daily fluid balance with mortality.

Conclusions

In this cohort of patients with AKI requiring RRT, a more positive mean daily fluid balance and intradialytic hypotension were associated with hospital mortality but not with RRT dependence at hospital discharge in survivors.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0624-8) contains supplementary material, which is available to authorized users.