Improving perioperative outcomes: fluid optimization with the esophageal Doppler monitor, a metaanalysis and review

Estimation of cardiac output variations induced by hemodynamic interventions using multi-beat analysis of arterial waveform: a comparative off-line study with transesophageal Doppler method during non-cardiac surgery

Multi-beat analysis (MBA) of the radial arterial pressure (AP) waveform is a new method that may improve cardiac output (CO) estimation via modelling of the confounding arterial wave reflection. We evaluated the precision and accuracy using the trending ability of the MBA method to estimate absolute CO and variations (ΔCO) during hemodynamic challenges. We reviewed the hemodynamic challenges (fluid challenge or vasopressors) performed when intra-operative hypotension occurred during non-cardiac surgery. The CO was calculated offline using transesophageal Doppler (TED) waveform (COTED) or via application of the MBA algorithm onto the AP waveform (COMBA) before and after hemodynamic challenges. We evaluated the precision and the accuracy according to the Bland & Altman method. We also assessed the trending ability of the MBA by evaluating the percentage of concordance with 15% exclusion zone between ΔCOMBA and ΔCOTED. A non-inferiority margin was set at 87.5%. Among the 58 patients included, 23 (40%) received at least 1 fluid challenge, and 46 (81%) received at least 1 bolus of vasopressors. Before treatment, the COTED was 5.3 (IQR [4.1-8.1]) l min-1, and the COMBA was 4.1 (IQR [3-5.4]) l min-1. The agreement between COTED and COMBA was poor with a 70% percentage error. The bias and lower and upper limits of agreement between COTED and COMBA were 0.9 (CI95 = 0.82 to 1.07) l min-1, -2.8 (CI95 = -2.71 to-2.96) l min-1 and 4.7 (CI95 = 4.61 to 4.86) l min-1, respectively. After hemodynamic challenge, the percentage of concordance (PC) with 15% exclusion zone for ΔCO was 93 (CI97.5 = 90 to 97)%. In this retrospective offline analysis, the accuracy, limits of agreements and percentage error between TED and MBA for the absolute estimation of CO were poor, but the MBA could adequately track induced CO variations measured by TED. The MBA needs further evaluation in prospective studies to confirm those results in clinical practice conditions.

PCO2 gap, its ratio to arteriovenous oxygen content, ScvO2 and lactate in high-risk abdominal surgery patients: An observational study

BACKGROUND

The difference between arterial and central venous carbon dioxide partial pressure (PCO₂ gap), a marker of oxygen delivery (DO₂) and oxygen consumption (VO₂) adequacy, has been evaluated as a promising prognostic tool in intensive care unit (ICU) patients. We therefore sought to study the association between intraoperative PCO₂ gap and postoperative complications (POC) in the perioperative setting of elective major abdominal surgery.

METHODS

We conducted a single-centre prospective observational study. All adult patients who underwent major planned abdominal surgery were eligible. PCO₂ gap was measured every 2 hours during surgery, at ICU admission and repeated 12 hours and 24 hours later. Severe POC within 28 days after surgery were defined as complications graded 3 or more according to Clavien-Dindo classification. Following a univariate analysis, a multivariable analysis using a logistic regression model was performed.

RESULTS

Ninety patients were included and divided into two groups according to the occurrence of POC. No significant difference was found between groups regarding baseline characteristics at inclusion. Thirty-nine (43%) patients developed postoperative complications. The median [IQR] intraoperative PCO₂ gap was significantly higher in patients who had complications (6.5 [5.5-7.3] mmHg) compared to those who did not (5.0 [3.9-5.8] mmHg; p < 0.001). The area under the receiver operating characteristic curve for occurrence of POC was 0.78 for the PCO₂ gap. After multivariable analysis, PCO₂ gap was found independently associated with POC (OR: 14.9, 95% CI [4.68-60.1], p < 0.001) with a threshold value of 6.2 mmHg. The duration of surgery (OR: 1.01, 95% CI [1.00; 1.01], p = 0.04) and the need for vasoactive support during surgery (OR: 5.76, 95% CI [1.72; 24.1], p = 0.006) were also independently associated with POC.

CONCLUSION

Intraoperative PCO₂ gap is a relevant predictive factor of severe postoperative complications in high-risk elective surgery patients.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03914976.

Evaluating the Efficacy of Two Regional Pain Management Modalities in Autologous Breast Reconstruction

At our institution, multimodal opiate-sparing pain management is the cornerstone of our enhanced recovery program for autologous breast reconstruction. The purpose of this study was to compare postoperative outcomes and pain control metrics following implementation of an enhanced recovery program with two different regional analgesia approaches.

Perioperative hemodynamic optimization: from guidelines to implementation-an experts' opinion paper

Despite a large body of evidence, the implementation of guidelines on hemodynamic optimization and goal-directed therapy remains limited in daily routine practice. To facilitate/accelerate this implementation, a panel of experts in the field proposes an approach based on six relevant questions/answers that are frequently mentioned by clinicians, using a critical appraisal of the literature and a modified Delphi process. The mean arterial pressure is a major determinant of organ perfusion, so that the authors unanimously recommend not to tolerate absolute values below 65 mmHg during surgery to reduce the risk of postoperative organ dysfunction. Despite well-identified limitations, the authors unanimously propose the use of dynamic indices to rationalize fluid therapy in a large number of patients undergoing non-cardiac surgery, pending the implementation of a “validity criteria checklist” before applying volume expansion. The authors recommend with a good agreement mini- or non-invasive stroke volume/cardiac output monitoring in moderate to high-risk surgical patients to optimize fluid therapy on an individual basis and avoid volume overload. The authors propose to use fluids and vasoconstrictors in combination to achieve optimal blood flow and maintain perfusion pressure above the thresholds considered at risk. Although purchase of disposable sensors and stand-alone monitors will result in additional costs, the authors unanimously acknowledge that there are data strongly suggesting this may be counterbalanced by a sustained reduction in postoperative morbidity and hospital lengths of stay. Beside existing guidelines, knowledge and explicit clinical reasoning tools followed by decision algorithms are mandatory to implement individualized hemodynamic optimization strategies and reduce postoperative morbidity and duration of hospital stay in high-risk surgical patients.

Review of Colonic Anastomotic Leakage and Prevention Methods

Although surgeries involving anastomosis are relatively common, anastomotic leakages are potentially deadly complications of colorectal surgeries due to increased risk of morbidity and mortality. As a result of the potentially fatal effects of anastomotic leakages, a myriad of techniques and treatments have been developed to treat these unfortunate cases. In order to better understand the steps taken to treat this complication, we have created a composite review involving some of the current and best treatments for colonic anastomotic leakage that are available. The aim of this article is to present a background review of colonic anastomotic leakage, as well as current strategies to prevent and treat this condition, for a broader audience, including scientist, engineers, and especially biomedical engineers.

[Perioperative fluid management in major abdominal surgery]

Intravascular fluid administration belongs to the cornerstones of perioperative treatment with a substantial impact on surgical outcome especially with respect to major abdominal surgery. By avoidance of hypovolemia and hypervolemia, adequate perioperative fluid management significantly contributes to the reduction of insufficient tissue perfusion as a determinant of postoperative morbidity and mortality. The effective use of intravascular fluids requires detailed knowledge of the substances as well as measures to guide fluid therapy. Fluid management already starts preoperatively and should be continued in the postoperative setting (recovery room, peripheral ward) considering a patient-adjusted and surgery-adjusted hemodynamic monitoring. Communication between all team members participating in perioperative care is essential to optimize fluid management.

Intraoperative Fluid Management in Patients Undergoing Spine Surgery: A Narrative Review

Fluid management has been widely recognized as an important component of the perioperative care in patients undergoing major procedures including spine surgeries. Patient- and surgery-related factors such as age, length of the surgery, massive intraoperative blood loss, and prone positioning, may impact the intraoperative administration of fluids. In addition, the type of fluid administered may also affect post-operative outcomes. Published literature describing intraoperative fluid management in patients undergoing major spine surgeries is limited and remains controversial. Therefore, we reviewed current literature on intraoperative fluid management and its association with post-operative complications in spine surgery.

Perioperative fluid management for major elective surgery

BACKGROUND

Adequate fluid balance before, during and after surgery may reduce morbidity. This review examines current concepts surrounding fluid management in major elective surgery.

METHOD

A narrative review was undertaken following a PubMed search for English language reports published before July 2019 using the terms 'surgery', 'fluids', 'fluid therapy', 'colloids', 'crystalloids', 'albumin', 'starch', 'saline', 'gelatin' and 'goal directed therapy'. Additional reports were identified by examining the reference lists of selected articles.

RESULTS

Fluid therapy is a cornerstone of the haemodynamic management of patients undergoing major elective surgery. Both fluid overload and hypovolaemia are deleterious during the perioperative phase. Zero-balance fluid therapy should be aimed for. In high-risk patients, individualized haemodynamic management should be titrated through the use of goal-directed therapy. The optimal type of fluid to be administered during major surgery remains to be determined.

CONCLUSION

Perioperative fluid management is a key challenge during major surgery. Individualized volume optimization by means of goal-directed therapy is warranted during high-risk surgery. In most patients, balanced crystalloids are the first choice of fluids to be used in the operating theatre. Additional research on the optimal type of fluid for use during major surgery is needed.

[Meta-analyses on measurement precision of non-invasive hemodynamic monitoring technologies in adults]

An ideal non-invasive monitoring system should provide accurate and reproducible measurements of clinically relevant variables that enables clinicians to guide therapy accordingly. The monitor should be rapid, easy to use, readily available at the bedside, operator-independent, cost-effective and should have a minimal risk and side effect profile for patients. An example is the introduction of pulse oximetry, which has become established for non-invasive monitoring of oxygenation worldwide. A corresponding non-invasive monitoring of hemodynamics and perfusion could optimize the anesthesiological treatment to the needs in individual cases. In recent years several non-invasive technologies to monitor hemodynamics in the perioperative setting have been introduced: suprasternal Doppler ultrasound, modified windkessel function, pulse wave transit time, radial artery tonometry, thoracic bioimpedance, endotracheal bioimpedance, bioreactance, and partial CO₂ rebreathing have been tested for monitoring cardiac output or stroke volume. The photoelectric finger blood volume clamp technique and respiratory variation of the plethysmography curve have been assessed for monitoring fluid responsiveness. In this manuscript meta-analyses of non-invasive monitoring technologies were performed when non-invasive monitoring technology and reference technology were comparable. The primary evaluation criterion for all studies screened was a Bland-Altman analysis. Experimental and pediatric studies were excluded, as were all studies without a non-invasive monitoring technique or studies without evaluation of cardiac output/stroke volume or fluid responsiveness. Most studies found an acceptable bias with wide limits of agreement. Thus, most non-invasive hemodynamic monitoring technologies cannot be considered to be equivalent to the respective reference method. Studies testing the impact of non-invasive hemodynamic monitoring technologies as a trend evaluation on outcome, as well as studies evaluating alternatives to the finger for capturing the raw signals for hemodynamic assessment, and, finally, studies evaluating technologies based on a flow time measurement are current topics of clinical research.

Angiotensin axis blockade, acute kidney injury, and perioperative morbidity in patients undergoing colorectal surgery: A retrospective cohort study

Patients undergoing surgery and taking angiotensin converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) are susceptible to complications related to intraoperative hypotension. Perioperative continuation of such medications in patients undergoing colorectal surgery may be associated with more harm than benefit, as these patients are often exposed to other risk factors which may contribute to intraoperative hypotension. Our objectives were to assess the incidence and severity of postinduction hypotension as well as the rates of acute kidney injury (AKI), 30-day all-cause mortality, 30-day readmission, and hospital length of stay in adult patients undergoing colorectal surgery who take ACEi/ARB.We performed a retrospective chart review of patients undergoing colorectal surgery of ≥4 hour duration at a tertiary care academic medical center between January 2011 and November 2016. The preoperative and intraoperative characteristics as well as postoperative outcomes were compared between patients taking ACEi/ARB and patients not taking these medications.Of the 1020 patients meeting inclusion criteria, 174 (17%) were taking either ACEi or ARB before surgery. Patients taking these medications were more likely to receive both postinduction and intraoperative phenylephrine and ephedrine. The incidences of postoperative AKI (P = .35), 30-day all-cause mortality (P = .36), 30-day hospital readmission (P = .45), and hospital length of stay (P = .25), were not significantly different between the 2 groups.Our results support the current recommendation that ACEi/ARB use is probably safe within the colorectal surgery population during the perioperative period. Intraoperative hypotension should be expected and treated with vasopressors.

Preload Dependence Is Associated with Reduced Sublingual Microcirculation during Major Abdominal Surgery

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Dynamic indices, such as pulse pressure variation, detect preload dependence and are used to predict fluid responsiveness. The behavior of sublingual microcirculation during preload dependence is unknown during major abdominal surgery. The purpose of this study was to test the hypothesis that during abdominal surgery, microvascular perfusion is impaired during preload dependence and recovers after fluid administration.

Methods

This prospective observational study included patients having major abdominal surgery. Pulse pressure variation was used to identify preload dependence. A fluid challenge was performed when pulse pressure variation was greater than 13%. Macrocirculation variables (mean arterial pressure, heart rate, stroke volume index, and pulse pressure variation) and sublingual microcirculation variables (perfused vessel density, microvascular flow index, proportion of perfused vessels, and flow heterogeneity index) were recorded every 10 min.

Results

In 17 patients, who contributed 32 preload dependence episodes, the occurrence of preload dependence during major abdominal surgery was associated with a decrease in mean arterial pressure (72 ± 9 vs. 83 ± 15 mmHg [mean ± SD]; P = 0.016) and stroke volume index (36 ± 8 vs. 43 ± 8 ml/m2; P &lt; 0.001) with a concomitant decrease in microvascular flow index (median [interquartile range], 2.33 [1.81, 2.75] vs. 2.84 [2.56, 2.88]; P = 0.009) and perfused vessel density (14.9 [12.0, 16.4] vs. 16.1 mm/mm2 [14.7, 21.4], P = 0.009), while heterogeneity index was increased from 0.2 (0.2, 0.4) to 0.5 (0.4, 0.7; P = 0.001). After fluid challenge, all microvascular parameters and the stroke volume index improved, while mean arterial pressure and heart rate remained unchanged.

Conclusions

Preload dependence was associated with reduced sublingual microcirculation during major abdominal surgery. Fluid administration successfully restored microvascular perfusion.

Goal-directed fluid therapy in urgent GAstrointestinal Surgery-study protocol for A Randomised multicentre Trial: The GAS-ART trial

INTRODUCTION

Intravenous fluid therapy during gastrointestinal surgery is a life-saving part of the perioperative care. Too little fluid may lead to hypovolaemia, decreased organ perfusion and circulatory shock. Excessive fluid administration increases postoperative complications, worsens pulmonary and cardiac function as well as the healing of surgical wounds. Intraoperative individualised goal-directed fluid therapy (GDT) and zero-balance therapy (weight adjusted) has shown to reduce postoperative complications in elective surgery, but studies in urgent gastrointestinal surgery are sparse. The aim of the trial is to test whether zero-balance GDT reduces postoperative mortality and major complications following urgent surgery for obstructive bowel disease or perforation of the gastrointestinal tract compared with a protocolled standard of care.

METHODS/ANALYSIS

This study is a multicentre, randomised controlled trial with planned inclusion of 310 patients. The randomisation procedure is stratified by hospital and by obstructive bowel disease and perforation of the gastrointestinal tract. Patients are allocated into either 'the standard group' or 'the zero-balance GDT group'. The latter receive intraoperative GDT (guided by a stroke volume algorithm) and postoperative zero-balance fluid therapy based on body weight and fluid charts. The protocolled treatment continues until free oral intake or the seventh postoperative day.The primary composite outcome is death, unplanned reoperations, life-threatening thromboembolic and bleeding complications, a need for mechanical ventilation or dialysis. Secondary outcomes are additional complications, length of hospital stay, length of stay in the intensive care unit, length of mechanical ventilation, readmissions and time to death. Follow-up is 90 days.We plan intention-to-treat analysis of the primary outcome.

ETHICS AND DISSEMINATION

The Danish Scientific Ethics Committee approved the GAS-ART trial before patient enrolment (J: SJ-436). Enrolment of patients began in August 2015 and is proceeding. We expect to publish the GAS-ART results in Summer 2019.

TRIAL REGISTRATION NUMBER

EudraCT 2015-000563-14.

Robot-assisted Partial Nephrectomy: Is Routine Urinary Catheterization Still Mandatory in the Era of Enhanced Recovery?

OBJECTIVE

To assess the benefits and safety of noncatheterization during robot-assisted partial nephrectomy within an enhanced recovery protocol.

MATERIALS AND METHODS

A single-center retrospective comparative study was carried out of consecutive patients who underwent a robot-assisted partial nephrectomy between February 2015 and December 2017 within an early recovery program. The patients who received a urinary catheter were compared with those who did not in terms of postoperative complications, acute urinary retention rates, urinary tract infection rates, and lengths of hospital stay.

RESULTS

Of the 145 patients who followed an early recovery program after robot-assisted partial nephrectomy in the study period, 96 received a urinary catheter and 49 did not. There was no significant difference between these 2 groups in terms of the rates of acute urinary retention (3% vs 6%, respectively; P = .393), urinary tract infection (3% vs 2%; P = .707), postoperative complications (14% vs 18%; P = .445), or readmissions within 30 days (8% vs 6%; P = .636). However, patients who did not receive a catheter had shorter initial and total (including readmissions) lengths of hospital stay (respectively 2.16 days vs 2.56 days; P = .058, and 2.27 days vs 3.40 days; P <.001).

CONCLUSION

Our findings challenge the routine use of urinary catheterization during robot-assisted partial nephrectomies. Noncatheterization does not seem to increase the risk of postoperative urinary retention. Only catheterizing specific at-risk patients may prove beneficial.

Changes in Clinical Practice Reduce the Rate of Anastomotic Leakage After Colorectal Resections

Background

Anastomotic leakage is a serious clinical problem after colorectal resections and is associated with a significantly increased length of stay, morbidity and mortality. The aim of the present study was to evaluate the effect of changes in clinical practice on anastomotic leakage rate after colorectal resections.

Methods

Retrospective cohort study based on prospectively collected data. All 894 patients with primary anastomosis after colorectal resection at a tertiary referral center between 2006 and 2013 were analyzed. Changes in clinical practice aiming at reducing the rate of anastomotic leakages were introduced in January 2010 and were characterized by exclusion of perioperative nonsteroidal anti-inflammatory drugs, introduction of intra-operative goal-directed fluid therapy and avoidance of primary anastomoses in emergency resections. The study population was divided into two groups, one treated before and one after the introduction of changes in clinical practice. Groups were compared regarding patient characteristics and incidence of anastomotic leakage.

Results

The cumulative incidence of anastomotic leakage after colorectal resections decreased from 10.0% (41 of 409) to 4.5% (22 of 485) after changing clinical practice, relative risk 0.45 (95% CI 0.27–0.75, p = 0.002). The adjusted odds ratio was 0.45 (0.26–0.78, p = 0.004). A separate analysis showed a decrease after colon resections from 9.1% (23 of 252) to 4.5% (14 of 310), relative risk 0.49 (0.26–0.94, p = 0.039), and from 11.5% (18 of 157) to 4.6% (8 of 175) after rectal resections, relative risk 0.40 (0.18–0.89, p = 0.024).

Conclusion

Implementing a structured change of clinical practice can significantly reduce the anastomotic leakage rate after colorectal resections.

Trial registration

Clinical trial registration number: ACTRN12617001497392.

Pleth variability index or stroke volume optimization during open abdominal surgery: a randomized controlled trial

Background

The impact of Goal Directed Fluid Therapy (GDFT) based on the non-invasive Pleth Variability Index (PVI) on clinical outcome after abdominal surgery has only sparingly been explored. The purpose of this study was to compare the effect of intraoperative GDFT guided by PVI to a control group using esophageal Doppler on the incidence of complications and length of hospital stay after major abdominal surgery. We hypothesized that there would be no difference between the groups.

Methods

This was a randomized controlled trial in a Swedish university hospital between November 2011 and January 2015; 150 patients scheduled for open abdominal surgery lasting 2 h or more were included. Exclusion criteria included hepatic resection or severe cardiac arrhythmia. The patients were randomized 1:1 to either the intervention group or the control group. The intervention group received intraoperative GDFT by administering fluid boluses of 3 ml/kg tetrastarch aiming at a PVI value below 10%, while GDFT in the control group aimed for optimization of stroke volume as assessed with esophageal Doppler. Blinded observers assessed complications until postoperative day 30 using pre-defined definitions, as well as length of hospital stay.

Results

One hundred and-fifty patients were randomized and 146 patients were available for the final data analysis. Median duration of surgery was 3 h. A total of 64 complications occurred in the PVI group (N = 74) and 70 in the Doppler group (N = 72) (p = 0.93). Median (IQR) length of stay was 8.0 (8.0) days in the PVI group and 8.0 (9.5) in the Doppler group (P = 0.57).

Conclusions

No difference in clinical outcome, as defined by number of postoperative complications, and length of hospital stay, was found when goal directed fluid therapy was applied using PVI as an alternative to esophageal Doppler. PVI appears to be an acceptable alternative to esophageal Doppler for goal directed fluid therapy during major open abdominal surgery.

Trial registration

Clinicaltrials.gov NCT01458678. Date of first registration October 20, 2011.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0579-4) contains supplementary material, which is available to authorized users.

Comparison of conventional fluid management with PVI-based goal-directed fluid management in elective colorectal surgery

Intraoperative fluid management is quite important in terms of postoperative organ perfusion and complications. Different fluid management protocols are in use for this purpose. Our primary goal was to compare the effects of conventional fluid management (CFM) with the Pleth Variability Index (PVI) guided goal-directed fluid management (GDFM) protocols on the amount of crystalloids administered, blood lactate, and serum creatinine levels during the intraoperative period. The length of hospital stay was our secondary goal. Seventy ASA I–II elective colorectal surgery patients were randomly assigned to CFM or GDFM for fluid management. The hemodynamic data and the data obtained from ABG were recorded at the end of induction and during the follow-up period at 1 h intervals. In the preoperative period and at 24 h postoperatively, blood samples were taken for the measurement of hemoglobin, Na, K, Cl, serum creatinine, albumin and blood lactate. In the first 24 h after surgery, oliguria and the time of first bowel movement were recorded. Length of hospital stay was also recorded. Intraoperative crystalloid administration and urine output were statistically significantly higher in CFM group (p < 0.001, p: 0.018). The end-surgery fluid balance was significantly lower in Group GDFM. Preoperative and postoperative Na, K, Cl, serum albumin, serum creatinine, lactate and hemoglobin values were similar between the groups. The time to passage of stool was significantly short in Group-GDFM compared to Group-CFM (p = 0.016). The length of hospital stay was found to be similar in both group. PVI-guided GDFM might be an alternative to CFM in ASA I–II patients undergoing elective colorectal surgery. However, further studies need to be carried out to search the efficiency and safety of PVI.

Intraoperative fluid management: Past and future, where is the evidence?

Currently, there is no consensus about the optimum intraoperative fluid therapy strategy. There is growing body of evidence supports the beneficial effects of adopting “Goal-directed therapy” over either the “liberal” or “restrictive” fluid therapy strategies. In this narrative review, we have presented the evidence to support the optimum strategy for intraoperative therapy. In conclusion, whatever the intravenous fluid replacement strategy used, the anesthesiologist must be prepared to adjust the composition and rate of the fluids administered to provide sufficient intravascular fluid volume for adequate perfusion of vital organs without overwhelming the glycocalyx function with fluid overloads.

Goal directed hemodynamic therapy based in esophageal Doppler flow parameters: A systematic review, meta-analysis and trial sequential analysis

BACKGROUND

Numerous studies have compared perioperative esophageal doppler monitoring (EDM) guided intravascular volume replacement strategies with conventional clinical volume replacement in surgical patients. The use of the EDM within hemodynamic algorithms is called 'goal directed hemodynamic therapy' (GDHT).

METHODS

Meta-analysis of the effects of EDM guided GDHT in adult non-cardiac surgery on postoperative complications and mortality using PRISMA methodology. A systematic search was performed in Medline, PubMed, EMBASE, and the Cochrane Library (last update, March 2015).

INCLUSION CRITERIA

Randomized clinical trials (RCTs) in which perioperative GDHT was compared to other fluid management.

PRIMARY OUTCOMES

Overall complications.

SECONDARY OUTCOMES

Mortality; number of patients with complications; cardiac, renal and infectious complications; incidence of ileus. Studies were subjected to quantifiable analysis, pre-defined subgroup analysis (stratified by surgery, type of comparator and risk); pre-defined sensitivity analysis and trial sequential analysis (TSA).

RESULTS

Fifty six RCTs were initially identified, 15 fulfilling the inclusion criteria, including 1,368 patients. A significant reduction was observed in overall complications associated with GDHT compared to other fluid therapy (RR=0.75; 95%CI: 0.63-0.89; P=0.0009) in colorectal, urological and high-risk surgery compared to conventional fluid therapy. No differences were found in secondary outcomes, neither in other subgroups. The impact on preventing the development of complications in patients using EDM is high, causing a relative risk reduction (RRR) of 50% for a number needed to treat (NNT)=6.

CONCLUSIONS

GDHT guided by EDM decreases postoperative complications, especially in patients undergoing colorectal surgery and high-risk surgery. However, no differences versus restrictive fluid therapy and in intermediate-risk patients were found.

Minimally Invasive Cardiac Output Monitoring: Agreement of Oesophageal Doppler, LiDCOrapid™ and Vigileo FloTrac™ Monitors in Non-Cardiac Surgery

There is lack of data about the agreement of minimally invasive cardiac output monitors, which make it impossible to determine if they are interchangeable or differ objectively in tracking physiological trends. We studied three commonly used devices: the oesophageal Doppler and two arterial pressure–based devices, the Vigileo FloTrac™ and LiDCOrapid™. The aim of this study was to compare the agreement of these three monitors in adult patients undergoing elective non-cardiac surgery. Measurements were taken at baseline and after predefined clinical interventions of fluid, metaraminol or ephedrine bolus. From 24 patients, 131 events, averaging 5.2 events per patient, were analysed. The cardiac index of LiDCOrapid versus FloTrac had a mean bias of −6.0% (limits of agreement from −51% to 39%) and concordance of over 80% to the three clinical interventions. The cardiac index of Doppler versus LiDCOrapid and Doppler versus FloTrac, had an increasing negative bias at higher mean cardiac outputs and there was significantly poorer concordance to all interventions. Of the preload-responsive parameters, Doppler stroke volume index, Doppler systolic flow time and FloTrac stroke volume variation were fair at predicting fluid responsiveness while other parameters were poor. While there is reasonable agreement between the two arterial pressure–derived cardiac output devices (LiDCOrapid and Vigileo FloTrac), these two devices differ significantly to the oesophageal Doppler technology in response to common clinical intraoperative interventions, representing a limitation to how interchangeable these technologies are in measuring cardiac output.

Pitfalls in haemodynamic monitoring in the postoperative and critical care setting

Haemodynamic monitoring is a vital part of daily practice in anaesthesia and intensive care. Although there is evidence to suggest that goal-directed therapy may improve outcomes in the perioperative period, which haemodynamic targets we should aim at to optimise patient outcomes remain elusive and controversial. This review highlights the pitfalls in commonly used haemodynamic targets, including arterial blood pressure, central venous pressure, cardiac output, central venous oxygen saturation and dynamic haemodynamic indices. Evidence suggests that autoregulation in regional organ circulation may change either due to chronic hypertension or different disease processes such as traumatic brain injury, cerebrovascular ischaemia or haemorrhage; this will influence the preferred blood pressure target. Central venous pressure can be influenced by multiple pathophysiological factors and, unless central venous pressure is very low, it is rarely useful as a predictor for fluid responsiveness. Central venous oxygen saturation can be easily increased by a high arterial oxygen tension, making it useless as a surrogate marker of good cardiac output or systemic oxygen delivery in the presence of hyperoxaemia. Many dynamic haemodynamic indices have been reported to predict fluid responsiveness, but they all have their own limitations. There is also insufficient evidence to support that giving fluid until the patient is no longer fluid responsive can improve patient-centred outcomes. With the exception in the context of preventing contrast-induced nephropathy, large randomised controlled studies suggest that excessive fluid treatment may prolong duration of mechanical ventilation without preventing acute kidney injury in the critically ill.

Goal-Directed Fluid Therapy Guided by Cardiac Monitoring During High-Risk Abdominal Surgery in Adult Patients: Cost-Effectiveness Analysis of Esophageal Doppler and Arterial Pulse Pressure Waveform Analysis

BACKGROUND

Several minimally invasive techniques for cardiac output monitoring such as the esophageal Doppler (ED) and arterial pulse pressure waveform analysis (APPWA) have been shown to improve surgical outcomes compared with conventional clinical assessment (CCA).

OBJECTIVE

To evaluate the cost-effectiveness of these techniques in high-risk abdominal surgery from the perspective of the French public health insurance fund.

METHODS

An analytical decision model was constructed to compare the cost-effectiveness of ED, APPWA, and CCA. Effectiveness data were defined from meta-analyses of randomized clinical trials. The clinical end points were avoidance of hospital mortality and avoidance of major complications. Hospital costs were estimated by the cost of corresponding diagnosis-related groups.

RESULTS

Both goal-directed therapy strategies evaluated were more effective and less costly than CCA. Perioperative mortality and the rate of major complications were reduced by the use of ED and APPWA. Cost reduction was mainly due to the decrease in the rate of major complications. APPWA was dominant compared with ED in 71.6% and 27.6% and dominated in 23.8% and 20.8% of the cases when the end point considered was "major complications avoided" and "death avoided," respectively. Regarding cost per death avoided, APPWA was more likely to be cost-effective than ED in a wide range of willingness to pay.

CONCLUSIONS

Cardiac output monitoring during high-risk abdominal surgery is cost-effective and is associated with a reduced rate of hospital mortality and major complications, whatever the device used. The two devices evaluated had negligible costs compared with the observed reduction in hospital costs. Our comparative studies suggest a larger effect with APPWA that needs to be confirmed by further studies.

Meta-analysis of the effect of goal-directed therapy on bowel function after abdominal surgery

Background

Intraoperative goal-directed therapy (GDT) was introduced to titrate intravenous fluids, with or without inotropic drugs, based on objective measures of hypovolaemia and cardiac output measurements to improve organ perfusion. This meta-analysis aimed to determine the effect of GDT on the recovery of bowel function after abdominal surgery.

Methods

MEDLINE, Embase, the Cochrane Library and PubMed databases were searched for randomized clinical trials and cohort studies, from January 1989 to June 2013, that compared patients who did, or did not, receive intraoperative GDT, and reported outcomes on the recovery of bowel function. Time to first flatus and first bowel motion, time to tolerate oral diet, postoperative nausea and vomiting, and primary postoperative ileus were included.

Results

Thirteen trials with 1399 patients were included in the analysis. GDT shortened the time to the first bowel motion (weighted mean difference (WMD −0·67, 95 per cent c.i. −1·23 to −0·11; P = 0·020) and time to tolerate oral intake (WMD −0·95, −1·81 to −0·10; P = 0·030), and reduced postoperative nausea and vomiting (risk difference −0·15, −0·26 to −0·03; P = 0·010). When only high-quality studies were included, GDT reduced only the time to tolerate oral intake (WMD −1·18, −2·03 to −0·33; P = 0·006). GDT was more effective outside enhanced recovery programmes and in patients undergoing colorectal surgery.

Conclusion

GDT facilitated the recovery of bowel function, particularly in patients not treated within enhanced recovery programmes and in those undergoing colorectal operations.

Clinical Predictors of a Low Central Venous Oxygen Saturation after Major Surgery: A Prospective Prevalence Study

Optimising perioperative haemodynamic status may reduce postoperative complications. In this prospective prevalence study, we investigated the associations between standard haemodynamic parameters and a low central venous oxygen saturation (ScvO2) in patients after major surgery. A total of 201 patients requiring continuous arterial and central venous pressure monitoring after major surgery were recruited. Simultaneous arterial and central venous blood gases, haemodynamic and biochemical data and perfusion index were obtained from patients at a single time-point within 24 hours of surgery. A low ScvO2 (<70%) was observed in 109 patients (54%). Use of mechanical ventilation, mean arterial pressure, central venous pressure, haemoglobin concentrations, arterial pH and lactate concentrations, arterial oxygen (PaO2) and carbon dioxide tensions (PaCO2) were all associated with a low ScvO2 in the univariate analyses. In the multivariate analysis, only a higher perfusion index (odds ratio [OR] 0.87, 95% confidence interval [CI] 0.78 to 0.98), PaO2 (OR 0.98 per mmHg increment, 95% CI 0.97 to 0.99) and PaCO2 (OR 0.88 per mmHg increment, 95% CI 0.82 to 0.95) and a lower central venous pressure (OR 1.14 per mmHg increment, 95% CI 1.04 to 1.25) were significantly associated with a reduced risk of a low ScvO2, all in a linear fashion. In conclusion, PaO2, PaCO2, perfusion index and central venous pressure were significant predictors of a low ScvO2 in patients after major surgery including cardiac surgery, suggesting that ScvO2 should always be interpreted with the arterial blood gases and that liberal perioperative fluid therapy aiming at a high central venous pressure may be detrimental in optimising ScvO2.

New tools for optimizing fluid resuscitation in acute pancreatitis

Acute pancreatitis (AP) is a frequent disease with degrees of increasing severity responsible for high morbidity. Despite continuous improvement in care, mortality remains significant. Because hypovolemia, together with microcirculatory dysfunction lead to poor outcome, fluid therapy remains a cornerstone of the supportive treatment. However, poor clinical evidence actually support the aggressive fluid therapy recommended in recent guidelines since available data are controversial. Fluid management remains unclear and leads to current heterogeneous practice. Different strategies may help to improve fluid resuscitation in AP. On one hand, integration of fluid therapy in a global hemodynamic resuscitation has been demonstrated to improve outcome in surgical or septic patients. Tailored fluid administration after early identification of patients with high-risk of poor outcome presenting inadequate tissue oxygenation is a major part of this strategy. On the other hand, new decision parameters have been developed recently to improve safety and efficiency of fluid therapy in critically ill patients. In this review, we propose a personalized strategy integrating these new concepts in the early fluid management of AP. This new approach paves the way to a wide range of clinical studies in the field of AP.

Early goal-directed therapy based on endotracheal bioimpedance cardiography: a prospective, randomized controlled study in coronary surgery

The objective was to compare the impact of an early goal-directed hemodynamic therapy based on cardiac output monitoring (Endotracheal Cardiac Output Monitor, ECOM) with a standard of care on postoperative outcome following coronary surgery. This prospective, controlled, parallel-arm trial randomized 100 elective primary coronary artery bypass grafting patients to a study group (ECOM; n = 50) or a control group (control; n = 50). In the ECOM group, hemodynamic therapy was guided by respiratory stroke volume variation and cardiac index given by the ECOM system. A standard of care was used in the control. Goal-directed therapy was started immediately after induction of anesthesia and continued until arrival in the intensive care unit (ICU). The primary endpoint was the time when patients fulfilled discharge criteria from hospital (possible hospital discharge). Secondary endpoints were the hospital discharge, the time to reach extubation, the length of stay in ICU, the number of major adverse cardiac events, and in-hospital mortality. Patients in the ECOM group received more often fluid loading and dobutamine. The time to reach extubation was reduced in the ECOM group: 510 min [360-1,110] versus 570 min [320-1,520], P = 0.005. No significant differences were found between both groups for possible hospital discharge [Hazard Ratio = 0.96 (95 % CI 0.64-1.45)] and hospital discharge [Hazard Ratio = 1.20 (95 % CI 0.79-1.81)]. A mini-invasive early goal-directed hemodynamic therapy based on ECOM can reduce the time to reach extubation but fails to significantly reduce the length of stay in hospital and the rate of major cardiac morbidity.

A Randomised Controlled Trial of Fluid Restriction Compared to Oesophageal Doppler-Guided Goal-Directed Fluid Therapy in Elective Major Colorectal Surgery within an Enhanced Recovery after Surgery Program

There is continued controversy regarding the benefits of goal-directed fluid therapy, with earlier studies showing marked improvement in morbidity and length-of-stay that have not been replicated more recently. The aim of this study was to compare patient outcomes in elective colorectal surgery patients having goal-directed versus restrictive fluid therapy. Inclusion criteria included suitability for an Enhanced Recovery After Surgery care pathway and patients with an American Society of Anesthesiologists Physical Status score of 1 to 3. Patients were intraoperatively randomised to either restrictive or Doppler-guided goal-directed fluid therapy. The primary outcome was length-of-stay; secondary outcomes included complication rate, change in haemodynamic variables and fluid volumes. One hundred patients, 50 in each group, were included in the analysis. Compared to restrictive therapy, goal-directed therapy resulted in a greater volume of intraoperative fluid, 2115 (interquartile range 1350 to 2560) ml versus 1500 (1200 to 2000) ml, P=0.008, and was associated with an increase in Doppler-derived stroke volume index from beginning to end of surgery, 43.7 (16.3) to 54.2 (21.1) ml/m2, P <0.001, in the latter group. Length-of-stay was similar, P=0.421. The number of patients with any complication (minor or major) was similar; 60% (30) versus 52% (26), P=0.42, or major complications, 1 (2%) versus 4 (8%), P=0.36, respectively. The increased perioperative fluid volumes and increased stroke volumes at the end of surgery in patients receiving goal-directed therapy did not translate to a significant difference in length-of-stay and we did not observe a difference in the number of patients experiencing minor or major complications.

Goal-directed fluid therapy based on stroke volume variations improves fluid management and gastrointestinal perfusion in patients undergoing major orthopedic surgery

OBJECTIVE

To evaluate the influence of stroke volume variation (SVV)-based goal-directed therapy (GDT) on splanchnic organ functions and postoperative complications in orthopedic patients.

SUBJECTS AND METHODS

Eighty patients scheduled for major orthopedic surgery under general anesthesia were randomly allocated to one of two equal groups to receive either intraoperative volume therapy guided by SVV (GDT) or standard fluid management (control). In the SVV group, patients received colloid boluses of 4 ml/kg to maintain an SVV <10% when in the supine position or an SVV <14% if prone. In the control group, fluids were given to maintain a mean arterial pressure >65 mm Hg, a heart rate <100 bpm, a central venous pressure of 8-14 mm Hg, and a urine output >0.5 ml/kg/h. Intraoperative organ perfusion, hemodynamic data, hospitalization, postoperative complications, and mortality were recorded.

RESULTS

The heart rate at the end of surgery was significantly lower (p < 0.05), there were fewer hypotensive episodes (p < 0.05), the arterial and gastric intramucosal pH were higher (p < 0.05 for both), the gastric intramucosal PCO2 was lower (p < 0.05), the intraoperative infused colloids and the total infused volume were lower (p < 0.05 for both), and the postoperative time to flatus was shorter (p < 0.05) in the GDT group than in the control group. No differences in the length of hospital stay, complications, or mortality were found between the groups.

CONCLUSION

SVV-based GDT during major orthopedic surgery reduced the volume of the required intraoperative infused fluids, maintained intraoperative hemodynamic stability, and improved the perioperative gastrointestinal function.

Predicting fluid responsiveness during infrarenal aortic cross-clamping in pigs

OBJECTIVE

Infrarenal aortic cross-clamping (ACC) induces hemodynamic disturbances that may affect respiratory-induced variations in stroke volume and, therefore, affect the ability of dynamic parameters such as pulse-pressure variation (PPV) to predict fluid responsiveness. Since this issue has not been investigated yet to authors' knowledge, the hypothesis was tested that ACC may change PPV and impair its ability to predict fluid responsiveness.

DESIGN

Prospective laboratory experiment.

SETTING

A university research laboratory.

PARTICIPANTS

Nineteen anesthetized and mechanically ventilated pigs.

INTERVENTIONS

Two courses of volume expansion were performed using 500 mL of saline before and during ACC. Animals were monitored using a systemic arterial catheter, and a pulmonary arterial catheter (stroke volume, central venous pressure, pulmonary arterial occlusion pressure). Animals were defined as responders to volume expansion if stroke volume increased ≥ 15%.

RESULTS

Before ACC, 13 animals were responders. Fluid responsiveness was predicted by a PPV ≥ 14% with a sensitivity of 77% (95% CI = 46%-95%) and a specificity of 83% (95% CI = 36%-97%). The area under the receiver operating characteristic curve was 0.90(95% CI = 0.67-0.99) and was higher than those generated for central venous pressure and pulmonary arterial occlusion pressure. ACC induced an increase in PPV (p<0.0005). During ACC, 8 animals were responders. An 18% PPV threshold discriminated between responders and non-responders to volume expansion, with a sensitivity of 87% (95% CI = 47%-98%) and a specificity of 54% (95% CI = 23%-83%). The area under the receiver operating characteristic curve was 0.72 (95% CI = 0.47-0.90) and was not different from those generated for central venous pressure and pulmonary arterial occlusion pressure.

CONCLUSIONS

ACC induced a significant increase in PPV and reduced its ability to predict fluid responsiveness.

Increasing use of less-invasive hemodynamic monitoring in 3 specialty surgical intensive care units: a 5-year experience at a tertiary medical center

INTRODUCTION

Less-invasive hemodynamic monitoring (eg, esophageal doppler monitoring [EDM] and arterial pressure contour analysis, FloTrac) is increasingly used as an alternative to pulmonary artery catheters (PACs) in critically ill intensive care unit (ICU).

HYPOTHESIS

The decrease in use of PACs is not associated with increased mortality.

METHODS

Five-year retrospective review of 1894 hemodynamically monitored patients admitted to 3 surgical ICUs in a university-affiliate, tertiary care urban hospital. Data included the number of admissions, diagnosis-related group discharge case mix, length of stay, insertion of monitoring devices (PAC, EDM, and FloTrac probes), administered intravenous vasoactive agents (β-predominant agonists--dobutamine, epinephrine, and dopamine; vasopressors--norepinephrine and phenylephrine), and mortality. Data from hospital administrative databases were compiled to create patient characteristic and monitoring variables across a 5-year time period, 2005 to 2009 inclusive. Chi-square for independent proportions, 1-way analysis of variance, and Kruskal-Wallis tests were used; tests for trend were conducted. An α level of .05 was considered significant. Statistical Package for the Social Sciences v14 was used for all statistical testing.

RESULTS

There was a significant change in the type of hemodynamic monitors inserted in 2 of the 3 surgical ICUs (in the general surgery and neurointensive care but not in the cardiac ICU) from PACs to less-invasive devices (FloTrac or EDM) during the 5-year study period (P < .001). There was no change in mortality rate over the time period (P = .492). There was an overall increase in the proportion of monitored patients who received intravenous vasoactive agents (P < .001) with a progressive shift from β-agonists to vasopressors (P < .002). Multivariate analyses indicated that age, case mix, and use of vasoactive agents were all independent predictors of inhospital mortality (P = .001) but that type of monitoring was not (P = .638).

CONCLUSIONS

In a 5-year period, the decreased insertions of PACs were replaced by increased utilization of less-invasive hemodynamic monitoring devices. This change in practice did not adversely impact mortality.

Intraoperative esophageal Doppler hemodynamic monitoring in free perforator flap surgery

Goal-directed fluid therapy optimizes cardiac output and flap perfusion during anesthesia. Intraoperative esophageal Doppler (ED) monitoring has been reported as more accurate and reliable, demonstrating improved surgical outcomes compared with central venous pressure and arterial catheter monitoring. A prospective study of patients undergoing free perforator (deep inferior epigastric artery perforator/anterolateral thigh) flap surgery with intraoperative ED monitoring (51 patients) or central venous pressure monitoring (53 patients) was undertaken. Fluid input included crystalloids, colloids, or blood products. Fluid output included urine, blood, or suctioned fluid. Postoperative fluid balance was calculated as fluid input - output. Fluid input between groups was not different. Fluid output was greater in the ED group (P = 0.008). The ED group showed less fluid balance (P = 0.023), less anesthetic time (P = 0.001), less hospital stay (mean 1.9 days; P = 0.147), less monitoring and flap complications (P = 0.062). ED monitoring demonstrated no monitoring complications, provides a favorable postoperative fluid balance, and may reduce flap complications and hospital stay.

Plethysmographic variability index (PVI) accuracy in predicting fluid responsiveness in anesthetized children

INTRODUCTION

Plethysmographic Variability Index (PVI) has been shown to accurately predict responsiveness to fluid loads in adults. The goal of this study was to evaluate PVI accuracy when predicting fluid responsiveness during noncardiac surgery in children.

MATERIAL AND METHODS

Children aged 2-10 years scheduled for noncardiac surgery under general anesthesia were included. PVI was assessed concomitantly with stroke volume index (SVI). A response to fluid load was defined by an SVI increase of more than 15%. A 10 ml·kg(-1) normal saline intravenous fluid challenge was administered before surgical incision and after anesthetic induction. After incision, fluid challenges were administered when SVI values decreased by more than 15% or where judged necessary by the anesthesiologist. Statistical analyses include receiving operator characteristics (ROC) analysis and the determination of gray zone method with an error tolerance of 10%.

RESULTS

Fifty-four patients were included, 97 fluid challenges administered and 45 responses recorded. Area under the curve of ROC curves was 0.85 [0.77-0.93] and 0.8 [0.7-0.89] for baseline PVI and SVI values, respectively. Corresponding gray zone limits were [10-17%] and [22-31 ml·m(-2)], respectively. PVI values exhibited different gray zone limits for pre-incision and postincision fluid challenges, whereas SVI values were comparable. PVI value percentages in the gray zone were 34% overall and 44% for challenges performed after surgical incision.

DISCUSSION

This study found both PVI and prechallenge SVI to be accurate when used to predict fluid load response during anesthetized noncardiac surgery in children. However, a third of recorded PVI values were inconclusive.

The role of transesophageal echocardiography in the intraoperative period

The goal of hemodynamic monitoring and management during major surgery is to guarantee adequate organ perfusion, a major prerequisite for adequate tissue oxygenation and thus, end-organ function. Further, hemodynamic monitoring should serve to prevent, detect, and to effectively guide treatment of potentially life-threatening hemodynamic events, such as severe hypovolemia due to hemorrhage, or cardiac failure. The ideal monitoring device does not exist, but some conditions must be met: it should be easy and operator-independently to use; it should provide adequate, reproducible information in real time. In this review we discuss in particular the role of intraoperative use of transesophageal echocardiography (TOE). Although TOE has gained special relevance in cardiac surgery, its role in major non cardiac surgery is still to be determined. We particularly focus on its ability to provide measurements of cardiac output (CO), and its role to guide fluid therapy. Within the last decade, concepts oriented on optimizing stroke volume and cardiac output mainly by fluid administration and guided by continuous monitoring of cardiac output or so called functional parameters of cardiac preload gained particular attention. Although they are potentially linked to an increased amount of fluid infusion, recent data give evidence that such pre-emptive concepts of hemodynamic optimization result in a decrease in morbidity and mortality. As TOE allows a real time direct visualization of cardiac structures, other potentially important advantages of its use also outside the cardiac surgery operation room can be postulated, namely the ability to evaluate the anatomical and functional integrity of the left and the right heart chambers. Finally, a practical approach to TOE monitoring is presented, based on a local experience.