Perioperative liberal versus restrictive fluid strategies and postoperative outcomes: a systematic review and metanalysis on randomised-controlled trials in major abdominal elective surgery

Effect of restrictive versus liberal fluid therapy for laparoscopic gastric surgery on postoperative complications: a randomized controlled trial

PURPOSE

Currently, laparoscopic surgery is a standard technique in the field of abdominal surgery. However, the most adequate fluid regimen during laparoscopic surgery remains unclear. The aim of this trial is to compare a restricted fluid therapy with a liberal fluid therapy for laparoscopic abdominal surgery. Our hypothesis was that restrictive fluid therapy would reduce postoperative complications better than liberal fluid therapy.

METHOD

In this randomized controlled trial, patients scheduled for laparoscopic gastric surgery were randomized to either the liberal group (receiving 7-10 ml/kg/h of crystalloid) or the restrictive group (receiving 1-2 ml/kg/h of crystalloid) for each stratum of surgical procedure from April 2017 to March 2019. For both groups, blood loss was replaced by an equal volume of hydroxyethyl starch. The primary endpoint was postoperative complications up to 30 days after surgery, according to the Clavien-Dindo classification.

RESULTS

We enrolled 148 patients, and 140 of these were randomized to either the liberal or the restrictive group after exclusion. As a result, 69 cases were included in the liberal group for analysis, and 67 patients composed the restrictive group. Median fluid administration for the liberal and restrictive groups was 2950 ml and 800 ml, respectively. As well, overall complications in the liberal and restrictive groups were 27.5% and 19.4%, respectively (risk ratio 0.71, 95% confidence interval 0.38-1.31, p value = 0.264).

CONCLUSION

Restricted fluid therapy and liberal fluid therapy did not show any statistical differences in postoperative complications after laparoscopic gastric surgery.

Fluid management in the septic peri-operative patient

PURPOSE OF REVIEW

This review provides insight into recent clinical studies involving septic peri-operative patients and highlights gaps in understanding fluid management. The aim is to enhance the understanding of safe fluid resuscitation to optimize peri-operative outcomes and reduce complications.

RECENT FINDINGS

Recent research shows adverse surgical and clinical outcomes with both under- and over-hydration of peri-operative patients. The kinetic of intravenous fluids varies significantly during surgery, general anaesthesia, and sepsis with damage to endothelial glycocalyx (EG), which increases vascular permeability and interstitial oedema. Among clinical anaesthesia, neuraxial anaesthesia and sevoflurane have less effect on EG. Hypervolemia and the speed and volume of fluid infusion are also linked to EG shedding. Despite improvement in the antisepsis strategies, peri-operative sepsis is not uncommon. Fluid resuscitation is the cornerstone of sepsis management. However, overzealous fluid resuscitation is associated with increased mortality in patients with sepsis and septic shock. Personalized fluid resuscitation based on a careful assessment of intravascular volume status, dynamic haemodynamic variables and fluid tolerance appears to be a safe approach. Balanced solutions (BS) are preferred over 0.9% saline in patients with sepsis and septic shock due to a potential reduction in mortality, when exclusive BS are used and/or large volume of fluids are required for fluid resuscitation. Peri-operative goal-directed fluid therapy (GDFT) using dynamic haemodynamic variables remains an area of interest in reducing postoperative complications and can be considered for sepsis management (Supplementary Digital Content).

SUMMARY

Optimization of peri-operative fluid management is crucial for improving surgical outcomes and reducing postoperative complications in patients with sepsis. Individualized and GDFT using BS is the preferred approach for fluid resuscitation in septic peri-operative patients. Future research should evaluate the interaction between clinical anaesthesia and EG, its implications on fluid resuscitation, and the impact of GDFT in septic peri-operative patients.

Stroke volume variation induced by lung recruitment maneuver to predict fluid responsiveness in patients receiving mechanical ventilation: A systematic review and meta-analysis

STUDY OBJECTIVE

The aim of this study was to evaluate the accuracy of lung recruitment maneuver induced stroke volume variation (ΔSVLRM) in predicting fluid responsiveness in mechanically ventilated adult patients by systematic review and meta-analysis.

METHODS

A comprehensive electronic search of relevant literature was conducted in PubMed, Web of Science, Cochrane Library, Ovid Medline, Embase and Chinese databases (including China National Knowledge Infrastructure, Wanfang and VIP databases). Review Manager 5.4, Meta-DiSc 1.4 and STATA 16.0 were selected for data analysis, and QUADAS-2 tool was used for quality assessment. Data from selected studies were pooled to obtain sensitivity, specificity, diagnostic likelihood ratio (DLR) of positive and negative, diagnostic odds ratio (DOR), and summary receiver operating characteristic curve.

RESULTS

A total of 6 studies with 256 patients were enrolled through March 2024. The risk of bias and applicability concerns for each included study were low, and there was no significant publication bias. There was moderate to substantial heterogeneity for the non-threshold effect, but not for the threshold effect. The combined sensitivity and specificity were 0.84 (95% CI, 0.77-0.90) and 0.79 (95% CI, 0.70-0.86), respectively. The DOR and the area under the curve (AUC) were 22.15 (95%CI, 7.62-64.34) and 0.90 (95% CI, 0.87-0.92), respectively. The positive and negative predictive values of DLR were 4.53 (95% CI, 2.50-8.18) and 0.19 (95% CI, 0.11-0.35), respectively. Fagan's nomogram showed that with a pre-test probability of 52%, the post-test probability reached 83% and 17% for the positive and negative tests, respectively.

CONCLUSIONS

Based on the currently available evidence, ΔSVLRM has a good diagnostic value for predicting the fluid responsiveness in adult patients undergoing mechanical ventilation. Given the heterogeneity and limitations of the published data, further studies with large sample sizes and different clinical settings are needed to confirm the diagnostic value of ΔSVLRM in predicting fluid responsiveness. PROSPERO registration number: CRD42023490598.

Conservative fluid resuscitation protocol does not reduce the incidence of reoperation for bleeding after emergency CABG

Reoperation for bleeding (ROB) after emergency coronary artery bypass grafting (eCABG) has been identified as an independent risk factor for mortality. Consecutively, the influence of fluid intake, fluid output, fluid balance, blood loss, and inotropic demand on ROB were analyzed. This retrospective single-center study included 265 patients undergoing eCABG between 2011 and 2020. From 2018, postoperative hemodynamic management was performed with lower volume administration and higher vasoactive support. The primary outcome measure was the incidence of ROB within 48 h according to altered fluid resuscitation strategy. Consecutively, the influence of fluid intake, fluid output, fluid balance, blood loss, and inotropic demand on ROB were analyzed. Incidence of ROB was independent from the volume resuscitation protocol (P = .3). The ROB group had a higher perioperative risk, which was observed in EuroSCORE II. Fluid intake (P = .021), fluid balance (P = .001), and norepinephrine administration (P = .004) were associated with ROB. Fluid output and blood loss were not associated with ROB (P = .22). Post-test probability was low among all variables. Although fluid management might have an impact on specific postoperative complications, different fluid resuscitation protocols did not alter the incidence of ROB after emergency CABG.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov registration number NCT04533698; date of registration: August 31, 2020 (retrospectively registered due to nature of the study); URL: https://classic.

CLINICALTRIALS

gov/ct2/show/NCT04533698.

Impact of perioperative fluid overload on the occurrence of postoperative pulmonary complications following lobectomy

Background

The incidence of pulmonary complications following lobectomy remains substantial, with postoperative fluid volume playing a pivotal role. However, the optimal management of fluids after lobectomy remains uncertain. This study aimed to establish a benchmark for perioperative fluid overload in patients undergoing pulmonary surgery by comparing the incidence of pulmonary complications following standard surgical procedures among patients with varying fluid volumes.

Methods

A retrospective analysis was conducted on adult patients with non-small cell lung cancer (NSCLC) who underwent lobectomy between January 2018 and January 2019. The primary exposure variable was fluid overload within the initial 24-hour period. The observation outcomes were postoperative pulmonary complications, acute kidney injury (AKI), and postoperative length of stay. Univariate and multivariate analyses were performed.

Results

Among the 300 patients included in this study, the low-volume group exhibited a significantly shorter postoperative hospital stay compared to the high-volume group (P=0.02). Furthermore, the low-volume group demonstrated a significantly lower incidence of postoperative atelectasis (P=0.03) and pulmonary infection (P=0.02) compared to the high-volume group. Moreover, logistic regression analysis revealed that the high-volume group had higher odds ratios (ORs) for developing atelectasis [OR: 2.611, 95% confidence interval (CI): 1.050-6.496, P=0.04] and pulmonary infection (OR: 2.642, 95% CI: 1.053-6.630, P=0.04) following lobectomy when compared to the low-volume group.

Conclusions

In patients with NSCLC undergoing lobectomy, reducing intravenous infusion after surgery while maintaining hemodynamic stability can effectively shorten hospitalization duration and mitigate the risk of postoperative atelectasis and pulmonary infection.

Effects of intraoperative different fluid therapy protocols on postoperative renal functions

PURPOSE

Planning intraoperative fluid therapy in patients undergoing major abdominal surgery is important. It was aimed to define the difference between fluid therapy protocols for renal function, bleeding and postoperative service follow-ups.

MATERIALS AND METHODS

This is an observational case-controlled prospective study. Sixty patients aged 18-65 years who had undergone pancreatic surgery between December 2023- February 2023 were included in the study. Liberal (Group 1; n = 30) and targeted fluid therapies (Group 2; n = 30) were administered to the patients. Liberal fluid therapy was planned with 8-10 ml/kg/h crystalloid infusion. The targeted fluid therapy (TFT) group (Group 2; n = 30) began with a 2 ml/kg/h crystalloid infusion at the baseline. Additional fluid boluses were given in 250 ml of colloid infused over 10 min if PVI was > 13% for at least five minutes. The patients were staged using the KDIGO (Kidney Disease: Improving Global Outcomes) criteria. The amount of bleeding during surgery was recorded for both groups.

RESULTS

No significant difference was observed in postoperative renal function. A significant difference was observed in the amount of intraoperative bleeding. The amount of bleeding was greater in patients managed with liberal fluid therapy. No significant difference was observed between the groups in the oral intake (hour), drain withdrawal (hour) mobilization (hour) and discharge (day) times and there isn't any statistically significant differance between groups in cost effectivity (p>0.05).

CONCLUSION

Kidney function was preserved during individualized targeted fluid therapy using non-invasive haemodynamic monitoring parameters.

CAROTID ARTERY ULTRASOUND FOR ASSESSING FLUID RESPONSIVENESS IN PATIENTS UNDERGOING MECHANICAL VENTILATION WITH LOW TIDAL VOLUME AND PRESERVED SPONTANEOUS BREATHING

ABSTRACT

Objective : This study aimed to investigate whether changes in carotid artery corrected flow time (ΔFTc bolus ) and carotid artery peak flow velocity respiratory variation (Δ V peak bolus ) induced by the fluid challenge could reliably predict fluid responsiveness in mechanically ventilated patients with a tidal volume < 8 mL/kg Predicted Body Weight while preserving spontaneous breathing. Methods : Carotid artery corrected flow time, Δ V peak, and hemodynamic data were measured before and after administration of 250 mL crystalloids. Fluid responsiveness was defined as a 10% or more increase in stroke volume index as assessed by noninvasive cardiac output monitoring after the fluid challenge. Results : A total of 43 patients with acute circulatory failure were enrolled in this study. Forty-three patients underwent a total of 60 fluid challenges. The ΔFTc bolus and Δ V peak bolus showed a significant difference between the fluid responsiveness positive group (n = 35) and the fluid responsiveness negative group (n = 25). Spearman correlation test showed that ΔFTc bolus and Δ V peak bolus with the relative increase in stroke volume index after fluid expansion ( r = 0.5296, P < 0.0001; r = 0.3175, P = 0.0135). Multiple logistic regression analysis demonstrated that ΔFTc bolus and Δ V peak bolus were significantly correlated with fluid responsiveness in patients with acute circulatory failure. The areas under the receiver operating characteristic curves of ΔFTc bolus and Δ V peak bolus for predicting fluid responsiveness were 0.935 and 0.750, respectively. The optimal cutoff values of ΔFTc bolus and Δ V peak bolus were 0.725 (sensitivity = 97.1%, specificity = 84%) and 4.21% (sensitivity = 65.7%, specificity = 80%), respectively. Conclusion : In mechanically ventilated patients with a tidal volume < 8 mL/kg while preserving spontaneous breathing, ΔFTc bolus and Δ V peak bolus could predict fluid responsiveness. The predictive performance of ΔFTc bolus was superior to Δ V peak bolus .

Modern fluid management in thoracic surgery

PURPOSE OF REVIEW

To provide an approach to perioperative fluid management for lung resection patients that incorporates the entire patient pathway in the context of international guidelines on enhanced recovery after surgery (ERAS).

RECENT FINDINGS

The concern with intraoperative fluid management is that giving too little or too much fluid is associated with worse outcomes after lung resection. However, it has not emerged as a key care element in thoracic ERAS programs probably due to the influence of other ERAS elements. Carbohydrate loading 2 h before surgery and the allowance of water until just prior to induction ensures the patient is both well hydrated and metabolically normal when they enter the operating room. Consequently, maintaining a euvolemic state during anesthesia can be achieved without goal-directed fluid therapy despite the recommendations of some guidelines. Intravenous fluids can be safely stopped in the immediate postoperative period.

SUMMARY

The goal of perioperative euvolemia can be achieved with the ongoing evolution and application of ERAS principles. A focus on the pre and postoperative phases of fluid management and a pragmatic approach to intraoperative fluid management negates the need for goal-directed fluid therapy in most cases.

Perioperative Fluid Management in Colorectal Surgery: Institutional Approach to Standardized Practice

The present review discusses restrictive perioperative fluid protocols within enhanced recovery after surgery (ERAS) pathways. Standardized definitions of a restrictive or liberal fluid regimen are lacking since they depend on conflicting evidence, institutional protocols, and personal preferences. Challenges related to restrictive fluid protocols are related to proper patient selection within standardized ERAS protocols. On the other hand, invasive goal-directed fluid therapy (GDFT) is reserved for more challenging disease presentations and polymorbid and frail patients. While the perfusion rate (mL/kg/h) appears less predictive for postoperative outcomes, the authors identified critical thresholds related to total intravenous fluids and weight gain. These thresholds are discussed within the available evidence. The authors aim to introduce their institutional approach to standardized practice.

High versus standard blood pressure target in hypertensive high-risk patients undergoing elective major abdominal surgery: a study protocol for the HISTAP randomized clinical trial

BACKGROUND

The intraoperative period is often characterized by hemodynamic instability, and intraoperative hypotension is a common complication. The optimal mean arterial pressure (MAP) target in hypertensive patients is still not clear. We hereby describe the protocol and detailed statistical analysis plan for the high versus standard blood pressure target in hypertensive high-risk patients undergoing elective major abdominal surgery: the HISTAP randomized clinical trial. The HISTAP trial aims at addressing whether the use of a higher intraoperative MAP target in high-risk hypertensive surgical patients scheduled for elective abdominal surgery would improve postoperative outcomes, as compared to the standard and recommended perioperative MAP, by using a composite outcome including a 30-day mortality from surgical intervention and at least one major organ dysfunction or new onset of sepsis and septic shock occurring 7 days after surgery.

METHODS

The HISTAP trial is an investigator-initiated, pragmatic, parallel-grouped, randomized, stratified, analyst-blinded trial with adequate allocation sequence generation, and allocation concealment. We will allocate 636 patients to a MAP target ≥ 80 mmHg (treatment group) or to a MAP target ≥65 mmHg (control group). The primary outcome is a composite outcome including a 30-day mortality from the operation and major organ complications. Secondary outcomes are mortality at 30 days, intensive care unit (ICU) length of stay, ICU readmission, Sequential Organ Failure Assessment (SOFA) scores recorded up to postoperative day 7, overall intraoperative fluid balance, vasopressors use, and the need for reoperation. An unadjusted χ2 test will be used for the primary outcome analysis. A Cox proportional hazards model will be used to adjust the association between the primary outcome and baseline covariates.

CONCLUSIONS

The HISTAP trial results will provide important evidence to guide clinicians' choice regarding the intraoperative MAP target in high-risk hypertensive patients scheduled for elective abdominal surgery.

Restrictive Versus Liberal Fluid Regimen in Refractory Sepsis and Septic Shock: A Systematic Review and Meta-Analysis

The optimal fluid management strategy for patients with sepsis remains a topic of debate. This meta-analysis aims to evaluate the impact of restrictive versus liberal fluid regimens on mortality, adverse events, and other clinical outcomes in patients with sepsis. We systematically reviewed 11 randomized controlled trials published between 2008 and 2023, comprising a total of 4,121 participants. The studies assessed 90-day mortality, 30-day mortality, adverse events, hospital length of stay, ICU admission rate, mechanical ventilation, ventilator-free days, ICU-free days, and vasopressor-free days. Quality assessments indicated minimal bias across the studies. The meta-analysis showed no statistically significant difference in 90-day mortality between restrictive and liberal fluid regimens (OR, 0.93; 95% CI, 0.80 to 1.70; P=0.30). Similar results were observed for 30-day mortality (OR, 0.73; 95% CI, 0.30 to 1.80; P=0.50). Adverse events were comparable between the two groups (OR, 0.81; 95% CI, 0.55 to 1.19; P=0.28). Furthermore, there were no significant differences in hospital length of stay (OR, 0.47; 95% CI, -0.85 to 1.80; P=0.48) or ICU admission rate (OR, 1.09; 95% CI, 0.66 to 1.77; P=0.75) between the restrictive and liberal fluid regimens. Regarding mechanical ventilation and ventilator-free days, no significant distinctions were observed (OR, 0.87; 95% CI, 0.65 to 1.17; P=0.48; OR, 0.99; 95% CI, -0.17 to 2.15; P=0.09, respectively). ICU-free days and vasopressor-free days also showed no significant differences between the two groups (OR, 0.97; 95% CI, -0.28 to 2.21; P=0.13; OR, -0.38; 95% CI, -1.14 to 0.37; P=0.32, respectively). This comprehensive meta-analysis of clinical trials suggests that restrictive and liberal fluid management strategies have comparable outcomes in patients with sepsis, including mortality, adverse events, and various clinical parameters. However, most studies favored restrictive fluid regimen over liberal approach regarding the number of vasopressor-free days, need for mechanical ventilation, adverse events, 30-day mortality, and 90-day mortality in sepsis patients.

A critical review of the perioperative fluid therapy and hemodynamic monitoring recommendations of the Enhanced Recovery of the Adult Pathway (RICA): A position statement of the fluid therapy and hemodynamic monitoring Subcommittee of the Hemostasis, Transfusion Medicine and Fluid Therapy Section (SHTF) of the Spanish Society of Anesthesiology and Critical Care (SEDAR)

In an effort to standardize perioperative management and improve postoperative outcomes of adult patients undergoing surgery, the Ministry of Health, through the Spanish Multimodal Rehabilitation Group (GERM), and the Aragonese Institute of Health Sciences, in collaboration with multiple Spanish scientific societies and based on the available evidence, published in 2021 the Spanish Intensified Adult Recovery (RICA) guideline. This document includes 12 perioperative measures related to fluid therapy and hemodynamic monitoring. Fluid administration and hemodynamic monitoring are not straightforward but are directly related to postoperative patient outcomes. The Fluid Therapy and Hemodynamic Monitoring Subcommittee of the Hemostasis, Transfusion Medicine and Fluid Therapy Section (SHTF) of the Spanish Society of Anesthesiology and Critical Care (SEDAR) has reviewed these recommendations and concluded that they should be revised as they do not follow an adequate methodology.

Effects of tidal volume challenge on the reliability of plethysmography variability index in hepatobiliary and pancreatic surgeries: a prospective interventional study

BACKGROUND

The plethysmography variability index (PVI) is a non-invasive, real-time, and automated parameter for evaluating fluid responsiveness, but it does not reliably predict fluid responsiveness during low tidal volume (VT) ventilation. We hypothesized that in a 'tidal volume challenge' with a transient increase in tidal volume from 6 to 8 ml Kg- 1, the changes in PVI could predict fluid responsiveness reliably.

METHOD

We performed a prospective interventional study in adult patients undergoing hepatobiliary or pancreatic tumor resections and receiving controlled low VT ventilation. The values for PVI, perfusion index, stroke volume variation, and stroke volume index (SVI) were recorded at baseline VT of 6 ml Kg- 1, 1 min after the VT challenge (8 ml Kg- 1), 1 min after VT 6 ml Kg- 1 reduced back again, and then 5 min after crystalloid fluid bolus 6 ml kg- 1 (actual body weight) administered over 10 min. The fluid responders were identified by SVI rise ≥ 10% after the fluid bolus.

RESULTS

The area under the receiver operating characteristic curve for PVI value change (ΔPVI6-8) after increasing VT from 6 to 8 ml Kg- 1 was 0.86 (95% confidence interval, 0.76-0.96), P < 0.001, 95% sensitivity, 68% specificity, and with best cut-off value of absolute change (ΔPVI6-8) = 2.5%.

CONCLUSION

In hepatobiliary and pancreatic surgeries, tidal volume challenge improves the reliability of PVI for predicting fluid responsiveness and changes in PVI values obtained after tidal volume challenge are comparable to the changes in SVI.

Intraoperative fluid administration volumes during pediatric liver transplantation and postoperative outcomes: A multicenter analysis

INTRODUCTION

Fluid administration is an important aspect of the management of children undergoing liver transplantation and may impact postoperative outcomes. Our aim was to evaluate the association between volume of intraoperative fluid administration and our primary outcome, the duration of postoperative mechanical ventilation following pediatric liver transplantation. Secondary outcomes included intensive care unit length of stay and hospital length of stay.

METHODS

We conducted a multicenter, retrospective cohort study using electronic data from three major pediatric liver transplant centers. Intraoperative fluid administration was indexed to weight and duration of anesthesia. Univariate and stepwise linear regression analyses were conducted.

RESULTS

Among 286 successful pediatric liver transplants, the median duration of postoperative mechanical ventilation was 10.8 h (IQR 0.0, 35.4), the median intensive care unit length of stay was 4.3 days (IQR 2.7, 6.8), and the median hospital length of stay was 13.6 days (9.8, 21.1). Univariate linear regression showed a weak correlation between intraoperative fluids and duration of ventilation (r2  = .037, p = .001). Following stepwise linear regression, intraoperative fluid administration remained weakly correlated (r2  = .161, p = .04) with duration of postoperative ventilation. The following variables were also independently correlated with duration of ventilation: center (Riley Children's Health versus Children's Health Dallas, p = .001), and open abdominal incision after transplant (p = .001).

DISCUSSION

The amount of intraoperative fluid administration is correlated with duration of postoperative mechanical ventilation in children undergoing liver transplantation, however, it does not seem to be a strong factor.

CONCLUSIONS

Other modifiable factors should be sought which may lead to improved postoperative outcomes in this highly vulnerable patient population.

Phenotypes of hemodynamic response to fluid challenge during anesthesia: a cluster analysis

BACKGROUND

The fluid challenge (FC) response is usually evaluated as binary, which may be inadequate to describe the complex interactions between heart function and vascular tone response after fluid administration. We applied a clustering approach to assess the different phenotypes of cardiovascular responses to FC administration, considering the associations of all the baseline variables potentially influencing pressure and flow response to a FC. Secondarily, we evaluated the reliability of baseline hemodynamic variables in discriminating fluid responsiveness, which is considered the standard approach at the bedside.

METHODS

Five merged datasets from elective surgical patients receiving a FC dose ≥4 mL/kg, infused over 10 minutes. In a principal component approach, hierarchical clustering was used to define hemodynamic phenotypes of response to FC administration. Hierarchical cluster analysis with Ward linkage was carried out to define similar patient groups using the Gower distance for the mixed combination of continuous and categorical variables. No a priori criteria of fluid responsiveness were applied. The area (AUC) under the pre-FC variables' receiver operating characteristic curves (ROC) was also built to predict fluid responsiveness, defined as SVI ≥10% after FC.

RESULTS

We analyzed 223 patients. The cluster analysis identified three hemodynamic clusters of patients: cluster 1 (98 patients, 44.0%) showed an average increase of mean arterial pressure (MAP) and Stroke Volume Index (SVI) of 17.3% (11.9-23.1) and 13.1% (0.5-23.4) at the end of FC, respectively. These patients showed baseline flow and pressure variables slightly below physiological ranges, with high pulse pressure variation (PPV). Cluster 2 (68 patients, 30.5%) showed no increase of MAP and SVI at the end of FC. These patients showed baseline flow and pressure variables within physiological ranges, with low hear rate (HR) and PPV. Cluster 3 (57 patients, 25.5%) showed no MAP increase and an SVI increase of 13.1 (2.1-19.6). These patients showed baseline pressure variables within physiological ranges, low flow variables associated to high HR and PPV. The pulse pressure variation (PPV) showed an AUC of 0.82 (0.03), with a grey zone ranging from 6% to 12%, including 86 (38.5%) patients.

CONCLUSIONS

Clustering analysis identified three hemodynamic clusters with different response phenotypes to FC. This promising approach may enhance the ability to detect fluid responsiveness at the bedside, by considering the specific association of parameters and not the presence of a single one, such as the PPV. In fact, in our cohort the reliability of the PPV was limited, showing high sensibility and specificity only above 12% and below 6%, respectively, and a grey zone including 38.5% of patients.

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.

Advances of perioperative acute kidney injury in elderly patients undergoing non-cardiac surgery

The risk of developing perioperative acute kidney injury (AKI) in elderly patients increases with age. The combined involvement of aging kidneys, coexisting multiple underlying chronic diseases, and increased exposure to potential renal stressors and nephrotoxic drugs or invasive procedures constitute susceptibility factors for AKI in elderly patients. The perioperative AKI in elderly patients undergoing noncardiac surgery has its own specific population characteristics, so it is necessary to further explore the characteristics of AKI in elderly patients in terms of epidemiology, clinical diagnosis, risk factors, and preventive and curative measures to provide meaningful clinical advice to improve prognosis, accelerate recovery, and reduce medical burden in elderly patients. Since AKI has the fastest-growing incidence in older patients and is associated with a worse prognosis, early detection, early diagnosis, and prevention of AKI are important for elderly patients in the perioperative period. Large, multicenter, randomized controlled clinical studies in elderly non-cardiac surgery patients with AKI can be conducted in the future, with the aim of providing the evidence to reduce of the incidence of AKI and to improve the prognosis of patients.

Perioperative Fluid Management and Volume Assessment

Fluid therapy is an integral component of perioperative care and helps maintain or restore effective circulating blood volume. The principal goal of fluid management is to optimize cardiac preload, maximize stroke volume, and maintain adequate organ perfusion. Accurate assessment of volume status and volume responsiveness is necessary for appropriate and judicious utilization of fluid therapy. To accomplish this, static and dynamic indicators of fluid responsiveness have been widely studied. This review discusses the overarching goals of perioperative fluid management, reviews the physiology and parameters used to assess fluid responsiveness, and provides evidence-based recommendations on intraoperative fluid management.

Intravenous-Therapy-Associated Circulatory Overload: A Retrospective Study of Forensic Cases

Background and Objective: Intravenous therapy is widely used in clinics to deliver medications and fluids to patients, and overuse may cause intravenous-infusion-associated circulatory overload (IACO) and death. However, forensic data on deaths from the overuse of intravenous therapy are limited. We performed a retrospective study to identify whether causes of death in forensic practice were associated with IACO. Methods: A total of 572 medical-related cases with a history of intravenous infusion who suffered from injuries or illnesses and died after treatment in hospitals were recruited from two centers of forensic medicine between 2002 and 2018. Results: The results demonstrated that 6.47% of cases (37/572) were exposed to an infusion overdose that resulted in deaths related to IACO, and 43.24% of cases (16/37) had a net fluid retention ranging from 3.0 L/d to 13.8 L/d. The highest case was administered 1.4 L blood products and 13.6 L fluids within 25 h. We observed significant decreases in red blood cells, hematocrit, hemoglobin, and platelets from the time of “on admission” to “before death”, except for white blood cells. Autopsy findings of 16 cases revealed some organ or tissue pathological alterations related to IACO, including pale-yellow liquid overflow under the abdominal epidermis, much transudate in body cavities, and lung edema with a high tissue density and no obvious slurry deposition in the alveolar lumen. Another 21 cases died after a rapid infusion rate ranging from 111 to 293 drops/min, which resulted from viral myocarditis on autopsy. Conclusions: Our data on excessive or irrational use of intravenous therapy indicate a severe circulatory overload, which may eventually result in lethal outcomes. Therefore, the use of improper intravenous therapy should be reduced to ameliorate adverse health consequences during clinical treatment.

Impact of the fluid challenge infusion rate on cardiac stroke volume during major spinal neurosurgery: a prospective single center randomized interventional trial

BACKGROUND

Fluid therapy, including the choice of a crystalloid or colloid infusion, the execution time of a volume bolus, and the expected volume need of a patient during surgery, varies greatly in clinical practice. Different goal directed fluid protocols have been developed, where fluid boluses guided by dynamic preload parameters are administered within a specific period.

OBJECTIVE

To study the efficacy of two fluid bolus infusion rates measured by the response of hemodynamic parameters.

DESIGN

Monocentric randomized controlled interventional trial.

SETTING

University hospital.

PATIENTS

Forty patients undergoing elective major spinal neurosurgery in prone position were enrolled, thirty-one were finally analyzed.

INTERVENTIONS

Patients were randomly assigned to receive 250 ml crystalloid and colloid boluses within 5 min (group 1) or 20 min (group 2) when pulse pressure variation (PPV) exceeded 14%.

MAIN OUTCOME MEASURES

Changes in stroke volume (SV), mean arterial pressure (MAP), and catecholamine administration.

RESULTS

Group 1 showed a greater increase in SV (P = 0.031), and MAP (P = 0.014), while group 2 still had higher PPV (P = 0.005), and more often required higher dosages of noradrenalin after fluid administration (P = 0.033). In group 1, fluid boluses improved CI (P < 0.01), SV (P < 0.01), and MAP (P < 0.01), irrespective of whether crystalloids or colloids were used. In group 2, CI and SV did not change, while MAP was slightly increased (P = 0.011) only after colloid infusion.

CONCLUSIONS

A fluid bolus within 5 min is more effective than those administered within 20 min and should therefore be the primary treatment option. Furthermore, bolus infusions administered within 20 min may result in volume overload without achieving relevant hemodynamic improvements.

TRIAL REGISTRATION

German Clinical Trials Register: DRKS00022917.

Intraoperative fluid balance and cardiac surgery-associated acute kidney injury: a multicenter prospective study

BACKGROUND

Recent data suggest the regime of fluid therapy intraoperatively in patients undergoing major surgeries may interfere in patient outcomes. The development of postoperative Acute Kidney Injury (AKI) has been associated with both Restrictive Fluid Balance (RFB) and Liberal Fluid Balance (LFB) during non-cardiac surgery. In patients undergoing cardiac surgery, this influence remains unclear. The study objective was to evaluate the relationship between intraoperative RFB vs. LFB and the incidence of Cardiac-Surgery-Associated AKI (CSA-AKI) and major postoperative outcomes in patients undergoing on-pump Coronary Artery Bypass Grafting (CABG).

METHODS

This prospective, multicenter, observational cohort study was set at two high-complexity university hospitals in Brazil. Adult patients who required postoperative intensive care after undergoing elective on-pump CABG were allocated to two groups according to their intraoperative fluid strategy (RFB or LFB) with no intervention.

RESULTS

The primary endpoint was CSA-AKI. The secondary outcomes were in-hospital mortality, cardiovascular complications, ICU Length of Stay (ICU-LOS), and Hospital LOS (H-LOS). After propensity score matching, 180 patients remained in each group. There was no difference in risk of CSA-AKI between the two groups (RR = 1.15; 95% CI, 0.85-1.56, p = 0.36). The in-hospital mortality, H-LOS and cardiovascular complications were higher in the LFB group. ICU-LOS was not significantly different between the two groups. ROCcurve analysis determined a fluid balance above 2500 mL to accurately predict in-hospital mortality.

CONCLUSION

Patients undergoing on-pump CABG with LFB when compared with patients with RFB present similar CSA-AKI rates and ICU-LOS, but higher in-hospital mortality, cardiovascular complications, and H-LOS.

Pressure response to fluid challenge administration in hypotensive surgical patients: a post-hoc pharmacodynamic analysis of five datasets

In this study we evaluated the effect of fluid challenge (FC) administration in elective surgical patients with low or normal blood pressure. Secondarily, we appraised the pharmacodynamic effect of FC in normotensive and hypotensive patients. We assessed five merged datasets of patients with a baseline mean arterial pressure (MAP) above or below 65 mmHg and assessed the changes of systolic, diastolic, mean and dicrotic arterial pressures, dynamic indexes of fluid responsiveness and arterial elastance over a 10-min infusion. The hemodynamic effect was assessed by considering the net area under the curve (AUC), the maximal percentage difference from baseline (d_max), the time when the maximal value was observed (t_max) and change from baseline at 5-min (d₅) after FC end. A stroke volume index increase > 10% with respect to the baseline value after FC administration indicated fluid response. Two hundred-seventeen patients were analysed [102 (47.0%) fluid responders]. On average, FC restored a MAP [Formula: see text] 65 mmHg after 5 min. The AUCs and the d_max of pressure variables and arterial elastance of hypotensive patients were all significantly greater than normotensive patients. Pressure variables and arterial elastance changes in the hypotensive group were all significantly higher at d₅ as compared to the normotensive group. In hypotensive patients, FC restores a MAP [Formula: see text] 65 mmHg after 5 min from infusion start. The hemodynamic profile of FC in hypotensive and normotensive patients is different; both the magnitude of pressure augmentation and duration is greater in the hypotensive group.

Fluids, vasopressors, and acute kidney injury after major abdominal surgery between 2015 and 2019: a multicentre retrospective analysis

BACKGROUND

Practice patterns related to intraoperative fluid administration and vasopressor use have potentially evolved over recent years. However, the extent of such changes and their association with perioperative outcomes, such as the development of acute kidney injury (AKI), have not been studied.

METHODS

We performed a retrospective analysis of major abdominal surgeries in adults across 26 US hospitals between 2015 and 2019. The primary outcome was AKI as defined by the Kidney Disease Improving Global Outcomes definition (KDIGO) using only serum creatinine criteria. Univariable linear predictive additive models were used to describe the dose-dependent risk of AKI given fluid administration or vasopressor use.

RESULTS

Over the study period, we observed a decrease in the volume of crystalloid administered, a decrease in the proportion of patients receiving more than 10 ml kg^-1 h^-1 of crystalloid, an increase in the amount of norepinephrine equivalents administered, and a decreased duration of hypotension. The incidence of AKI increased between 2016 and 2019. An increase of crystalloid administration from 1 to 10 ml kg^-1 h^-1 was associated with a 58% decreased risk of AKI.

CONCLUSIONS

Despite decreased duration of hypotension during the study period, decreased fluid administration and increased vasopressor use were associated with increased incidence of AKI. Crystalloid administration below 10 ml kg^-1 h^-1 was associated with an increased risk of AKI. Although no causality can be concluded, these data suggest that prevention and treatment of hypotension during abdominal surgery with liberal use of vasopressors at the expense of fluid administration is associated with an increased risk of postoperative AKI.

Prediction of fluid responsiveness. What’s new?

Although the administration of fluid is the first treatment considered in almost all cases of circulatory failure, this therapeutic option poses two essential problems: the increase in cardiac output induced by a bolus of fluid is inconstant, and the deleterious effects of fluid overload are now clearly demonstrated. This is why many tests and indices have been developed to detect preload dependence and predict fluid responsiveness. In this review, we take stock of the data published in the field over the past three years. Regarding the passive leg raising test, we detail the different stroke volume surrogates that have recently been described to measure its effects using minimally invasive and easily accessible methods. We review the limits of the test, especially in patients with intra-abdominal hypertension. Regarding the end-expiratory occlusion test, we also present recent investigations that have sought to measure its effects without an invasive measurement of cardiac output. Although the limits of interpretation of the respiratory variation of pulse pressure and of the diameter of the vena cava during mechanical ventilation are now well known, several recent studies have shown how changes in pulse pressure variation itself during other tests reflect simultaneous changes in cardiac output, allowing these tests to be carried out without its direct measurement. This is particularly the case during the tidal volume challenge, a relatively recent test whose reliability is increasingly well established. The mini-fluid challenge has the advantage of being easy to perform, but it requires direct measurement of cardiac output, like the classic fluid challenge. Initially described with echocardiography, recent studies have investigated other means of judging its effects. We highlight the problem of their precision, which is necessary to evidence small changes in cardiac output. Finally, we point out other tests that have appeared more recently, such as the Trendelenburg manoeuvre, a potentially interesting alternative for patients in the prone position.

Influence of 3% Hypertonic Saline Versus 0.9% Saline on Intraoperative Maintenance Fluid Requirements in Adult Patients Undergoing Major Open Abdominal Surgeries: Randomized Controlled Study

BACKGROUND

Three percent hypertonic saline (3% HTS) acts like an osmotic buffer and draws fluid from the extracellular space into the intravascular compartment. Primary objective was to evaluate whether use of 3% HTS resulted in a difference in intraoperative maintenance fluid requirement versus 0.9% saline (NS). Secondary objectives were to evaluate differences in 24 h fluid requirements and safety of 3% HTS.

METHODS

Adult patients of either sex, 18-65 years, undergoing elective major open abdominal surgeries were randomized to receive infusions of 3% HTS or NS at 1 ml/kg/hr through large bore peripheral i.v cannulas, or central venous catheters after anesthesia induction. Intraoperative maintenance fluids were administered to maintain mean arterial pressure (≥70 mmHg), urine output (≥0.5 ml/kg/hr) and central venous pressure of 8-10 cm H₂O.

RESULTS

Ninety-three patients completed the study (46 in 3% HTS and 47 in NS group). No difference was seen in the volume of intraoperative maintenance fluids (3% HTS vs NS; 2243.9 ± 896.7 ml vs 2093.6 ± 868.7 ml; P = 0.34). Similarly, the 24 h postoperative fluid requirement was not different (3% HTS vs NS; 2006.6 ± 398.6 ml vs 2018.3 ± 389.3 ml; P = 0.94). Patients in 3% HTS group had statistically but not clinically significant higher serum sodium values at postoperative 12th and 24 h. No complication like thrombophlebitis or tissue ischemia was reported due to administration of 3% HTS through peripheral lines.

CONCLUSION

Administration of 3% HTS did not reduce intraoperative maintenance fluid requirements in patients undergoing major open abdominal surgeries.

TRIAL REGISTRATION

CTRI/2019/09/021032.

Should fluid management in thoracic surgery be goal directed?

PURPOSE OF REVIEW

To find a reliable answer to the question in the title: Should fluid management in thoracic surgery be goal directed?

RECENT FINDINGS

'Moderate' fluid regimen is the current recommendation of fluid management in thoracic anesthesia, however, especially in more risky patients; 'Goal-Directed Therapy' (GDT) can be a more reliable approach than just 'moderate'. There are numerous studies examining its effects in general anesthesia; albeit mostly retrospective and very heterogenic. There are few studies of GDT in thoracic anesthesia with similar drawbacks.

SUMMARY

Although the evidence level is low, GDT is generally associated with fewer postoperative complications. It can be helpful in decision-making for volume-optimization, timing of fluid administration, and indication of vasoactive agents.