Systematic review of the literature for the use of oesophageal Doppler monitor for fluid replacement in major abdominal surgery

Intraoperative Goal-directed Fluid Therapy in Elective Major Abdominal Surgery: A Meta-analysis of Randomized Controlled Trials

Objectives:

To compare the effects of intraoperative goal-directed fluid therapy (GDFT) with conventional fluid therapy, and determine whether there was a difference in outcome between studies that did and did not use Enhanced Recovery After Surgery (ERAS) protocols.

Methods:

Meta-analysis of randomized controlled trials of adult patients undergoing elective major abdominal surgery comparing intraoperative GDFT versus conventional fluid therapy. The outcome measures were postoperative morbidity, length of stay, gastrointestinal function and 30-day mortality.

Results:

A total of 23 studies were included with 2099 patients: 1040 who underwent GDFT and 1059 who received conventional fluid therapy. GDFT was associated with a significant reduction in morbidity (risk ratio [RR] 0.76, 95% confidence interval [CI] 0.66–0.89, P = 0.0007), hospital length of stay (LOS; mean difference −1.55 days, 95% CI −2.73 to −0.36, P = 0.01), intensive care LOS (mean difference −0.63 days, 95% CI −1.18 to −0.09, P = 0.02), and time to passage of feces (mean difference −0.90 days, 95% CI −1.48 to −0.32 days, P = 0.002). However, no difference was seen in mortality, return of flatus, or risk of paralytic ileus. If patients were managed in an ERAS pathway, the only significant reductions were in intensive care LOS (mean difference −0.63 days, 95% CI −0.94 to −0.32, P < 0.0001) and time to passage of feces (mean difference −1.09 days, 95% CI −2.03 to −0.15, P = 0.02). If managed in a traditional care setting, a significant reduction was seen in both overall morbidity (RR 0.69, 95% CI 0.57 to −0.84, P = 0.0002) and total hospital LOS (mean difference −2.14, 95% CI −4.15 to −0.13, P = 0.04).

Conclusions:

GDFT may not be of benefit to all elective patients undergoing major abdominal surgery, particularly those managed in an ERAS setting.

Monitoring high-risk patients: minimally invasive and non-invasive possibilities

Over the past decades, there has been considerable progress in the field of less invasive haemodynamic monitoring technologies. Substantial evidence has accumulated, which supports the continuous measurement and optimization of flow-based variables such as stroke volume, that is, cardiac output, in order to prevent occult hypoperfusion and consequently to improve patients' outcome in the perioperative setting. However, there is a striking gap between the developments in haemodynamic monitoring and the increasing evidence to implement defined treatment protocols based on the measured variables, and daily clinical routine. Recent trials have shown that perioperative morbidity and mortality is higher than anticipated. This emphasizes the need for the anaesthesia community to address this issue and promotes the implementation of proven concepts into clinical practice in order to improve patients' outcome, especially in high-risk patients. The advances in minimally invasive and non-invasive monitoring techniques can be seen as a driving force in this respect, as the degree of invasiveness of any monitoring tool determines the frequency of its application, especially in the operating room (OR). From this point of view, we are very confident that some of these minimally invasive and non-invasive haemodynamic monitoring technologies will become an inherent part of our monitoring armamentarium in the OR and in the intensive care unit (ICU).

Left Ventricular Dilation and Pulmonary Vasodilatation after Surgical Shunt for Treatment of Pre-Sinusoidal Portal Hypertension

Objective

The aim of this study was to prospectively investigate the long-term cardiovascular and pulmonary hemodynamic effects of surgical shunt for treatment of portal hypertension (PH) due to Schistosomiasis mansoni.

Location

The University of São Paulo Medical School, Brazil; Public Practice.

Methods

Hemodynamic evaluation was performed with transesophageal Doppler and contrast-enhanced echocardiography (ECHO) on twenty-eight participants with schistosomal portal hypertension. Participants were divided into two groups according to the surgical procedure used to treat their schistosomal portal hypertension within the last two years: group 1—distal splenorenal shunt (DSRS, n = 13) and group 2—esophagogastric devascularization and splenectomy (EGDS, n = 15).

Results

The cardiac output (5.08 ± 0.91 L/min) and systolic volume (60.1 ± 5.6 ml) were increased (p = 0.001) in the DSRS group. DSRS participants had a significant increase (p < 0.0001) in their left ventricular end-systolic and end-diastolic diameters as well as in their left ventricular end-diastolic and end-systolic volumes (p < 0.001) compared with the preoperative period. No statistically significant difference was found in the patients who underwent EGDS. ECHO revealed intrapulmonary vasodilatation (IPV) in 18 participants (64%), 9 DSRS and 9 EGDS (p > 0.05).

Conclusions

The late increase in the cardiac output, stroke volume and left ventricular diameters demonstrated left ventricular dilatation after a distal splenorenal shunt. ECHO revealed a greater prevalence for IPV in patients with schistosomiasis than has previously been described in patients with PH from liver cirrhosis.

Comparing cardiac output monitors and defining agreement: A systematic review and meta-analysis

BACKGROUND

Measuring cardiac output is common in critical care and perioperative medicine. Different monitoring systems are often judged against others in comparative studies. There is no agreed standard or definition on which to base the conclusions of such studies.

OBJECTIVES

To review comparative studies of cardiac output monitors using an agreement:tolerability index (ATI) as a measure of monitor precision. To compare the ATI of a monitor with the conclusions of authors regarding agreement and clinical utility.

DESIGN

Systematic review of comparative studies of cardiac output monitoring systems. The precision of each monitor was standardised against an ATI using a tolerability interval based on the normal range for cardiac index. The conclusions of each study were described as positive, neutral or negative, depending on whether authors reported the monitor to be acceptably precise and/or clinically useful. Comparison was made between the precision of a monitor and the likelihood of it being favoured by authors.

DATA SOURCES

PubMed was searched up to March 2012.

ELIGIBILITY CRITERIA

Studies published in English that compared two or more methods for measuring cardiac output in adult humans.

RESULTS

A total of 213 papers documenting 409 separate comparisons of two methods of measuring cardiac output were included. ATIs for the different comparisons varied from 0.07 to 6.84 (where an ATI < 1 indicates acceptable agreement, 1-2 marginal and >2 unacceptable agreement). Thirty-one percent of authors defined their own terms for acceptable agreement. ATI was only moderately correlated with the conclusions of the authors (Spearman rho = 0.47, P < 0.0001).

CONCLUSIONS

Authors should define what constitutes acceptable agreement a priori when reporting comparative studies of cardiac output monitors. The ATI and the tolerability interval may be a useful basis for helping define acceptable precision.

Fluid management in abdominal surgery: what, when, and when not to administer

The entire team (including anesthesiologists, surgeons, and intensive care physicians) must work together (before, during, and after abdominal surgery) to determine the optimal amount (quantity) and type (quality) of fluid necessary in the perioperative period. The authors present an overview of the basic principles that underlie fluid management, including evidence-based recommendations (where tenable) and a rational approach for when and what to administer.

Implementation of enhanced recovery after surgery (ERAS) in gynaecological oncology

OBJECTIVES

To evaluate the outcomes of enhanced recovery after surgery (ERAS) implementation in a gynaecological oncology centre.

METHOD

Non-randomised control trial, evaluating morbidity outcomes, before and after implementation of ERAS programme. All consecutive major gynaecological oncology operations performed during two specified periods were included. Data were collected prospectively for a study group in the initial 7.5 months of ERAS implementation and compared with a consecutive historic control group from the exact same period, the year before. Patients' characteristics and perioperative outcomes were compared. Further analysis stratified abdominal and laparoscopic surgery.

RESULTS

In total, 265 cases identified; 99 patients followed ERAS and 99 historic controls, managed with a traditional peri-operative approach, the exact same period the year before (vulval surgery excluded, 67 cases). Groups were comparable in demographics and co-morbidities (age, BMI, ASA, WHO), level of surgery and 30 days post-operative complication (grading Clavien-Dindo classification) and readmission rates (p > 0.05). Overall, the post-operative length of hospital stay (LOS) was significantly reduced for patients who followed ERAS (4.29 ± 2.78 days versus 7.23 ± 5.68 days, p < 0.001). Stratification to subgroups was based on the type of surgery, abdominal versus laparoscopic. Those who underwent abdominal surgery and followed ERAS benefited the maximum (LOS: 5.09 ± 2.74 days versus 8.70 ± 5.75, p < 0.001) CONCLUSIONS: ERAS programme is feasible and safe in Gynae-oncology. In this study, there was a reduction of 3.61 (SE: 0.78, CI 95 %) days in the total LOS, in major abdominal Gynae-oncology surgery (level 3 and 4) without affecting complication or readmission rates.

Intraoperative Fluid Restriction in Pancreatic Surgery: A Double Blinded Randomised Controlled Trial

Background

Perioperative fluid restriction in a variety of operations has shown improvement of: complications, recovery of gastrointestinal function and length of stay (LOS). We investigated effects of crystalloid fluid restriction in pancreatic surgery. Our hypothesis: enhanced recovery of gastrointestinal function.

Methods

In this double-blinded randomized trial, patients scheduled to undergo pancreatoduodenectomy (PD) were randomized: standard (S:10ml/kg/hr) or restricted (R:5ml/kg/hr) fluid protocols. Primary endpoint: gastric emptying scintigraphically assessed on postoperative day 7.

Results

In 66 randomized patients, complications and 6-year survival were analyzed. 54 patients were analyzed in intention to treat: 24 S-group and 30 R-group. 32 patients actually underwent a PD and 16 patients had a palliative gastrojejunostomy bypass operation in the full protocol analysis. The median gastric emptying time (T½) was 104 minutes (S-group, 95% confidence interval: 74–369) versus 159 minutes (R-group, 95% confidence interval: 61–204) (P = 0.893, NS). Delayed gastric emptying occurred in 10 patients in the S-group and in 13 patients in the R-group (45% and 50%, P = 0.779, NS). The primary outcome parameter, gastric emptying time, did not show a statistically significant difference between groups.

Conclusion

A fluid regimen of 10ml/kg/hr or 5ml/kg/hr during pancreatic surgery did not lead to statistically significant differences in gastric emptying. A larger study would be needed to draw definite conclusions about fluid restriction in pancreatic surgery.

Trial registration

ISRCTN62621488

Enhanced Recovery After Surgery: Which Components, If Any, Impact on The Systemic Inflammatory Response Following Colorectal Surgery?: A Systematic Review

Enhanced Recovery or Fast Track Recovery after Surgery protocols (ERAS) have significantly changed perioperative care following colorectal surgery and are promoted as reducing the stress response to surgery.The present systematic review aimed to examine the impact on the magnitude of the systemic inflammatory response (SIR) for each ERAS component following colorectal surgery using objective markers such as C-reactive protein (CRP) and interleukin-6 (IL-6).A literature search was performed of the US National Library of Medicine (MEDLINE), EMBASE, PubMed, and the Cochrane Database of Systematic Reviews using appropriate keywords and subject headings to February 2015.Included studies had to assess the impact of the selected ERAS component on the SIR using either CRP or IL-6.Nineteen studies, including 1898 patients, were included. Fourteen studies (1246 patients) examined the impact of laparoscopic surgery on the postoperative markers of SIR. Ten of these studies (1040 patients) reported that laparoscopic surgery reduced postoperative CRP. One study (53 patients) reported reduced postoperative CRP using opioid-minimising analgesia. One study (142 patients) reported no change in postoperative CRP following preoperative carbohydrate loading. Two studies (108 patients) reported conflicting results with respect to the impact of goal-directed fluid therapy on postoperative IL-6. No studies examined the effect of other ERAS components, including mechanical bowel preparation, antibiotic prophylaxis, thromboprophylaxis, and avoidance of nasogastric tubes and peritoneal drains on markers of the postoperative SIR following colorectal surgery.The present systematic review shows that, with the exception of laparoscopic surgery, objective evidence of the effect of individual components of ERAS protocols in reducing the stress response following colorectal surgery is limited.

Postoperative fluid management

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

Effect of intraoperative transesophageal Doppler-guided fluid therapy versus central venous pressure-guided fluid therapy on renal allograft outcome in patients undergoing living donor renal transplant surgery: a comparative study

PURPOSE

Transesophageal Doppler (TED)-guided intraoperative fluid therapy has shown to noninvasively optimize intravascular volume and reduce postoperative morbidity. The aim of this study was to compare the effects of Doppler-guided intraoperative fluid administration and central venous pressure (CVP)-guided fluid therapy on renal allograft outcome and postoperative complications.

METHODS

A prospective nonrandomized active controlled study was conducted on end-stage renal disease patients scheduled for living donor renal transplant surgery. 110 patients received intraoperative fluid guided by corrected flow time (FTc) and variation in stroke volume values obtained by continuous TED monitoring. Data of 104 patients in whom intraoperative fluid administration was guided by CVP values were retrospectively obtained for a control.

RESULTS

The amount of intraoperative fluid given in the study group (12.20 ± 4.24 ml/kg/h) was significantly lower than in the controls (22.21 ± 4.67 ml/kg/h). The amount of colloid used was also significantly less and fewer recipients were seen to require colloid (69 vs 85%). The mean arterial pressures were comparable throughout. CVP reached was 7.18 ± 3.17 mmHg in the study group. It was significantly higher in the controls (13.42 ± 3.12 mmHg). The postoperative graft function and rate of dysfunction were comparable. Side-effects like postoperative dyspnoea (4.8 vs 0%) and tissue edema (9.6 vs 2.7%) were higher in the controls.

CONCLUSIONS

FTc-guided intraoperative fluid therapy achieved the same rate of immediate graft function as CVP-guided fluid therapy but used a significantly less amount of fluid. The incidence of postoperative complications related to fluid overload was also reduced. The use of TED may replace invasive central line insertions in the future.

Defining goals of resuscitation in the critically ill patient

There is still no "universal" consensus on an optimal endpoint for goal directed therapy (GDT) in the critically ill patient. As in other areas of medicine, this should help providers to focus on a more "individualized approach" rather than a protocolized approach to ensure proper patient care. Hemodynamic optimization needs more than simply blood pressure, heart rate, central venous pressure and urine output monitoring. It is essential to also monitor flow variables (cardiac output/stroke volume) and dynamic parameters of fluid responsiveness whenever available. This article will provide a review of current and trending approaches of the goals of resuscitation in the critically ill patient.

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.

[Goal-directed hemodynamic therapy: Concepts, indications and risks]

Goal-directed hemodynamic therapy is becoming increasingly more interesting for anesthesiologists and intensive care physicians. Meta-analyses of studies evaluating perioperative therapy algorithms demonstrated a reduction of postoperative morbidity compared to the previous clinical practices. In this review article the basic concepts of goal-directed hemodynamic therapy and the principles of previously employed therapy algorithms are described and discussed. Furthermore, the questions of how these therapy strategies can be transferred into daily clinical practice and whether these therapeutic approaches might even bear risks for patients are elucidated.

Colloids versus crystalloids in objective-guided fluid therapy, systematic review and meta-analysis. Too early or too late to draw conclusions

INTRODUCTION

Several clinical trials on Goal directed fluid therapy (GDFT) were carried out, many of those using colloids in order to optimize the preload. After the decision of European Medicines Agency, there is such controversy regarding its use, benefits, and possible contribution to renal failure. The objective of this systematic review and meta-analysis is to compare the use of last-generation colloids, derived from corn, with crystalloids in GDFT to determine associated complications and mortality.

METHODS

A bibliographic research was carried out in MEDLINE PubMed, EMBASE and Cochrane Library, corroborating randomized clinical trials where crystalloids are compared to colloids in GDFT for major non-cardiac surgery in adults.

RESULTS

One hundred thirty references were found and among those 38 were selected and 29 analyzed; of these, six were included for systematic review and meta-analysis, including 390 patients. It was observed that the use of colloids is not associated with the increase of complications, but rather with a tendency to a higher mortality (RR [95% CI] 3.87 [1.121-13.38]; I(2)=0.0%; p=0.635).

CONCLUSIONS

Because of the limitations of this meta-analysis due to the small number of randomized clinical trials and patients included, the results should be taken cautiously, and the performance of new randomized clinical trials is proposed, with enough statistical power, comparing balanced and unbalanced colloids to balanced and unbalanced crystalloids, following the protocols of GDFT, considering current guidelines and suggestions made by groups of experts.

Routine clinical markers of the magnitude of the systemic inflammatory response after elective operation: a systematic review

BACKGROUND

Operative injury to the body from all procedures causes a stereotypical cascade of neuroendocrine, cytokine, myeloid, and acute phase responses. This response has been examined commonly by the use of cortisol, interleukin-6 (IL-6), white cell count, and C-reactive protein (CRP). We aimed to determine which markers of the systemic inflammatory response were useful in determining the magnitude of injury after elective operations.

METHODS

A systematic review of the literature was performed using surgery, endocrine response, systemic inflammatory response, cortisol, IL-6, white cell count, and CRP. For each analyte the studies were grouped according to whether the operative injury was considered to be minor, moderate, or major and then by the operative procedure.

RESULTS

A total of 164 studies were included involving 14,362 patients. The IL-6 and CRP responses clearly were associated with the magnitude of operative injury and the invasiveness of the operative procedure. For example, the peak CRP response increased from 52 mg/L with cholecystectomy to 123 mg/L with colorectal cancer resection, 145 mg/L with hip replacement, 163 mg/L after abdominal aortic aneurysm repair, and 189 mg/L after open cardiac surgery. There also appeared to be a difference between minimally invasive/laparoscopic and open procedures such as cholecystectomy (27 vs 80 mg/L), colorectal cancer resection (97 vs 133 mg/L), and aortic aneurysm repair (132 vs 180 mg/L).

CONCLUSION

Peak IL-6 and CRP concentrations consistently were associated with the magnitude of operative injury and operative procedure. These markers may be useful in the objective assessment of which components of Enhanced Recovery after Surgery are likely to improve patient outcome and to assess the possible impact of operative injury on immune function.

Evaluation of the utility of the Vigileo FloTrac(™) , LiDCO(™) , USCOM and CardioQ(™) to detect hypovolaemia in conscious volunteers: a proof of concept study

It is important to detect and treat hypovolaemia; however, detection is particularly challenging in the conscious, spontaneously breathing patient. Eight healthy male volunteers were monitored using four minimally invasive monitors: Vigileo FloTrac(™) ; LiDCOrapid(™) ; USCOM 1A; and CardioQ(™) oesophageal Doppler. Monitor output and clinical signs were recorded during incremental venesection of 2.5% estimated blood volume aliquots to a total of 20% blood volume removed. A statistically significant difference from baseline stroke volume was detected after 2.5% blood loss using the LiDCO (p = 0.007), 7.5% blood loss using the USCOM (p = 0.019), and 12.5% blood loss using the CardioQ (p = 0.046) and the FloTrac (p = 0.028). Receiver operator characteristic curves for predicting > 10% blood loss had areas under the curve of 0.68-0.82. The minimally invasive cardiac output devices tested can detect blood loss by a reduction in stroke volume in awake volunteers, and may have a role in guiding fluid replacement in conscious patients with suspected hypovolaemia.

Anesthesia for esophagectomy

Esophagectomy is a high-risk operation with significant perioperative morbidity and mortality. Attention to detail in many areas of perioperative management should lead to an aggregation of marginal gains and improvement in postoperative outcome. This review addresses preoperative assessment and patient selection, perioperative care (focusing on pulmonary prehabilitation, ventilation strategies, goal-directed fluid therapy, analgesia, and cardiovascular complications), minimally invasive surgery, and current evidence for enhanced recovery in esophagectomy.

Systematic review of preoperative, intraoperative and postoperative risk factors for colorectal anastomotic leaks

BACKGROUND

Anastomotic leak (AL) represents a dreaded complication following colorectal surgery, with a prevalence of 1-19 per cent. There remains a lack of consensus regarding factors that may predispose to AL and the relative risks associated with them. The objective was to perform a systematic review of the literature, focusing on the role of preoperative, intraoperative and postoperative factors in the development of colorectal ALs.

METHODS

A systematic review was performed to identify adjustable and non-adjustable preoperative, intraoperative and postoperative factors in the pathogenesis of AL. Additionally, a severity grading system was proposed to guide treatment.

RESULTS

Of 1707 papers screened, 451 fulfilled the criteria for inclusion in the review. Significant preoperative risk factors were: male sex, American Society of Anesthesiologists fitness grade above II, renal disease, co-morbidity and history of radiotherapy. Tumour-related factors were: distal site, size larger than 3 cm, advanced stage, emergency surgery and metastatic disease. Adjustable risk factors were: smoking, obesity, poor nutrition, alcohol excess, immunosuppressants and bevacizumab. Intraoperative risk factors were: blood loss/transfusion and duration of surgery more than 4 h. Stomas lessen the consequences but not the prevalence of AL. In the postoperative period, CT is the most commonly used imaging tool, with or without rectal contrast, and a C-reactive protein level exceeding 150 mg/l on day 3-5 is the most sensitive biochemical marker. A five-level classification system for AL severity and appropriate management is presented.

CONCLUSION

Specific risk factors and their potential correction or indications for stoma were identified. An AL severity score is proposed to aid clinical decision-making.

Current tools for assessing heart function and perfusion adequacy

PURPOSE OF REVIEW

Many devices are currently available for measuring cardiac output and function. Understanding the utility of these devices requires an understanding of the determinants of cardiac output and cardiac function, and the use of these parameters in the management of critically ill patients. This review stresses the meaning of the physiological measures that are obtained with these devices and how these values can be used.

RECENT FINDINGS

Evaluation of devices for haemodynamic monitoring can include just measurement of cardiac output, the potential to track spontaneous changes in cardiac output or changes produced by volume infusions or vasoactive drugs, or the ability to assess cardiac function. Each of these puts different demands on the need for accuracy, precision, and reliability of the devices, and thus devices must be evaluated based on the clinical need.

SUMMARY

Evaluation of cardiac function is useful when first dealing with an unstable patient, but for ongoing management measurement of cardiac output itself is key and even more so the trend in relationship to the patient's overall condition. This evaluation would be greatly benefited by the addition of objective measures of tissue perfusion.

Comparison of monitoring performance of bioreactance versus esophageal Doppler in pediatric patients

Background and Aims:

Cardiac output (CO) monitoring and goal-directed therapy during major abdominal surgery is currently used to decrease postoperative complications. However, few monitors are currently available for pediatric patients. Nicom^® is a noninvasive CO monitoring technique based on the bioreactance principle (analysis of frequency variations of a delivered oscillating current traversing the thoracic cavity). Nicom^® may be a useful monitor for pediatric patients.

Subjects and Methods:

Pediatric patients undergoing major abdominal surgery under general anesthesia with cardiac monitoring by transesophageal Doppler (TED) were included. Continuously recorded hemodynamic variables obtained from both bioreactance and TED were compared. Data were analyzed using the Bland–Altman method.

Results:

A total of 113 pairs of cardiac index (CI) measurments from 16 patients were analyzed. Mean age was 59 months (95% CI: 42-75) and mean weight was 17 kg (95% CI: 15–20). In the overall population, Bland–Altman analysis revealed a bias of 0.4 L/min/m², precision of 1.55 L/min/m², limits of agreement of −1.1 to 1.9 L/min/m² and a percentage error of 47%. For children weighing >15 kg, results were: Bias 0.51 L/min/m², precision 1.17 L/min/m², limits of agreement −0.64 to 1.66 L/min/m² and percentage error 34%.

Conclusion:

Simultaneous CI estimations made by bioreactance and TED showed high percentage of errors that is not clinically acceptable. Bioreactance cannot be considered suitable for monitoring pediatric patients.

Technological advances in perioperative monitoring: Current concepts and clinical perspectives

Minimal mandatory monitoring in the perioperative period recommended by Association of Anesthetists of Great Britain and Ireland and American Society of Anesthesiologists are universally acknowledged and has become an integral part of the anesthesia practice. The technologies in perioperative monitoring have advanced, and the availability and clinical applications have multiplied exponentially. Newer monitoring techniques include depth of anesthesia monitoring, goal-directed fluid therapy, transesophageal echocardiography, advanced neurological monitoring, improved alarm system and technological advancement in objective pain assessment. Various factors that need to be considered with the use of improved monitoring techniques are their validation data, patient outcome, safety profile, cost-effectiveness, awareness of the possible adverse events, knowledge of technical principle and ability of the convenient routine handling. In this review, we will discuss the new monitoring techniques in anesthesia, their advantages, deficiencies, limitations, their comparison to the conventional methods and their effect on patient outcome, if any.

Dehydration and fluid volume kinetics before major open abdominal surgery

INTRODUCTION

Assessment of dehydration in the preoperative setting is of potential clinical value. The present study uses urine analysis and plasma volume kinetics, which have both been validated against induced changes in body water in volunteers, to study the incidence and severity of dehydration before open abdominal surgery begins.

METHODS

Thirty patients (mean age 64 years) had their urine analysed before major elective open abdominal surgery for colour, specific weight, osmolality and creatinine. The results were scored and the mean taken to represent a 'dehydration index'. Thereafter, the patients received an infusion of 5 ml/kg of Ringer's acetate intravenously for over 15 min. Blood was sampled for 70 min and the blood haemoglobin concentration used to estimate the plasma volume kinetics.

RESULTS

Distribution of fluid occurred more slowly (P < 0.01) and the elimination half-life was twice as long (median 40 min, not significant) in the 11 patients (37%) diagnosed to be moderately dehydrated as compared with euhydrated patients. The dehydration index indicated that the fluid deficit in these patients corresponded to 2.5% of the body weight, whereas the deficit in the others was 1%. In contrast, the 11 patients who later developed postoperative nausea and vomiting had a very short elimination half-life, only 9 min (median, P < 0.01). These patients were usually euhydrated but had microalbuminuria (P < 0.03) and higher natriuresis (P < 0.01).

CONCLUSIONS

The degree of dehydration before major surgery was modest as evidenced both by urine sampling and volume kinetic analysis.

Comparing a non-invasive hemodynamic monitor with minimally invasive monitoring during major open abdominal surgery

As part of the enhanced recovery after surgery (ERAS) protocol, the goal-directed fluid management with hemodynamic monitoring can effectively guide perioperative fluid use and significantly improve the outcomes in high-risk patients undergoing major surgeries. Several minimally invasive and non-invasive monitoring devices are commercially available for clinical use. As part of an internal evaluation, we reported the results from three different hemodynamic monitoring devices used in a patient undergoing a major abdominal surgery.

Consensus guidelines for enhanced recovery after gastrectomy: Enhanced Recovery After Surgery (ERAS®) Society recommendations

BACKGROUND

Application of evidence-based perioperative care protocols reduces complication rates, accelerates recovery and shortens hospital stay. Presently, there are no comprehensive guidelines for perioperative care for gastrectomy.

METHODS

An international working group within the Enhanced Recovery After Surgery (ERAS®) Society assembled an evidence-based comprehensive framework for optimal perioperative care for patients undergoing gastrectomy. Data were retrieved from standard databases and personal archives. Evidence and recommendations were classified according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system and were discussed until consensus was reached within the group. The quality of evidence was rated 'high', 'moderate', 'low' or 'very low'. Recommendations were graded as 'strong' or 'weak'.

RESULTS

The available evidence has been summarized and recommendations are given for 25 items, eight of which contain procedure-specific evidence. The quality of evidence varies substantially and further research is needed for many issues to improve the strength of evidence and grade of recommendations.

CONCLUSION

The present evidence-based framework provides comprehensive advice on optimal perioperative care for the patient undergoing gastrectomy and facilitates multi-institutional prospective cohort registries and adequately powered randomized trials for further research.

Perioperative fluid restriction

Perioperative fluid management of the colorectal surgical patient has evolved significantly over the last five decades. Older notions espousing aggressive hydration have been shown to be associated with increased complications. Newer data regarding fluid restriction has shown an association with improved outcomes. Management of perioperative fluid administration can be considered in three primary phases: In the preoperative phase, data suggests that avoidance of preoperative bowel preparation and avoidance of undue preoperative dehydration can improve outcomes. Although the type of intraoperative fluid given does not have a significant effect on outcome, data do suggest that a restrictive fluid regimen results in improved outcomes. Finally, in the postoperative phase of fluid management, a fluid-restrictive regimen, coupled with early enteral feeding also seems to result in improved outcomes.

A prospective comparison of a noninvasive cardiac output monitor versus esophageal Doppler monitor for goal-directed fluid therapy in colorectal surgery patients

BACKGROUND

Goal-directed fluid therapy (GDFT) is associated with improved outcomes after surgery. The esophageal Doppler monitor (EDM) is widely used, but has several limitations. The NICOM, a completely noninvasive cardiac output monitor (Cheetah Medical), may be appropriate for guiding GDFT. No prospective studies have compared the NICOM and the EDM. We hypothesized that the NICOM is not significantly different from the EDM for monitoring during GDFT.

METHODS

One hundred adult patients undergoing elective colorectal surgery participated in this study. Patients in phase I (n = 50) had intraoperative GDFT guided by the EDM while the NICOM was connected, and patients in phase II (n = 50) had intraoperative GDFT guided by the NICOM while the EDM was connected. Each patient's stroke volume was optimized using 250-mL colloid boluses. Agreement between the monitors was assessed, and patient outcomes (postoperative pain, nausea, and return of bowel function), complications (renal, pulmonary, infectious, and wound complications), and length of hospital stay (LOS) were compared.

RESULTS

Using a 10% increase in stroke volume after fluid challenge, agreement between monitors was 60% at 5 minutes, 61% at 10 minutes, and 66% at 15 minutes, with no significant systematic disagreement (McNemar P > 0.05) at any time point. The EDM had significantly more missing data than the NICOM. No clinically significant differences were found in total LOS or other outcomes. The mean LOS was 6.56 ± 4.32 days in phase I and 6.07 ± 2.85 days in phase II, and 95% confidence limits for the difference were -0.96 to +1.95 days (P = 0.5016).

CONCLUSIONS

The NICOM performs similarly to the EDM in guiding GDFT, with no clinically significant differences in outcomes, and offers increased ease of use as well as fewer missing data points. The NICOM may be a viable alternative monitor to guide GDFT.

Perioperative Haemodynamic Optimisation

During the latest years, a number of studies have confirmed the benefits of perioperative haemodynamic optimisation on surgical mortality and postoperative complication rate. This process requires the use of advanced haemodynamic monitoring with the purpose of guiding therapies to reach predefined goals. This review aim to present recent evidence on perioperative goal directed therapy (GDT), with an emphasis in some aspects that may merit further investigation. In order to maximise the benefits on outcomes, GDT must be implemented as early as possible; intravascular volume optimisation should be in accordance with the response of the preload-reserve, goals should be individualised and adequacy of the intervention must be also assessed; non-invasive or minimally invasive monitoring should be used and, finally, side effects of every therapy should be taken into account in order to avoid undesired complications. New drugs and technologies, particularly those exploring the venous side of the circulation, may improve in the future the effectiveness and facilitate the implementation of this group of therapeutic interventions.

Enhanced recovery for esophagectomy: a systematic review and evidence-based guidelines

OBJECTIVE

This article aims to provide the first systematic review of enhanced recovery after surgery (ERAS) programs for esophagectomy and generate guidelines.

BACKGROUND

ERAS programs use multimodal approaches to reduce complications and accelerate recovery. Although ERAS is well established in colorectal surgery, experience after esophagectomy has been minimal. However, esophagectomy remains an extremely high-risk operation, commonly performed in patients with significant comorbidities. Consequently, ERAS may have a significant role to play in improving outcomes. No guidelines or reviews have been published in esophagectomy.

METHODS

We undertook a systematic review of the PubMed, EMBASE, and the Cochrane databases in July 2012. The literature was searched for descriptions of ERAS in esophagectomy. Components of successful ERAS programs were determined, and when not directly available for esophagectomy, extrapolation from related evidence was made. Graded recommendations for each component were then generated.

RESULTS

Six retrospective studies have assessed ERAS for esophagectomy, demonstrating favorable morbidity, mortality, and length of stay. Methodological quality is, however, low. Overall, there is little direct evidence for components of ERAS, with much derived from nonesophageal thoracoabdominal surgery.

CONCLUSIONS

ERAS in principle seems logical and safe for esophagectomy. However, the underlying evidence is poor and lacking. Despite this, a number of recommendations for practice and research can be made.

Optimizing perioperative hemodynamics: what is new?

PURPOSE OF REVIEW

Using perioperative goal-directed therapy (GDT) or peroperative hemodynamic optimization significantly reduces postoperative complications and risk of death in patients undergoing noncardiac major surgeries. In this review, we discuss the main changes in the field of perioperative optimization over the last few years.

RECENT FINDINGS

One of the key aspects that has changed in the last decade is the shift from invasive monitoring with pulmonary artery catheters (PACs) to less or minimally invasive monitoring systems. The evaluation of intravascular fluid volume deficits has also changed dramatically from the use of static indices to the assessment of fluid responsiveness using either dynamic indices or functional hemodynamic. Finally, attention has been directed toward more restrictive strategies of crystalloids as maintenance fluids.

SUMMARY

GDT is safe and more likely to tailor the amount of fluids given to the amount of fluids actually needed. This approach includes assessment of fluid responsiveness and, if necessary, the use of inotropes; moreover, this approach can be coupled with a restrictive strategy for maintenance fluids. These strategies have been increasingly incorporated into protocols for perioperative hemodynamic optimization in high-risk patients undergoing major surgery, resulting in more appropriate use of fluids, vasopressors, and inotropes.

Endpoints of resuscitation: what are they anyway?

Hemodynamic optimization of surgical patients during and after surgery in the Surgical Intensive Care Unit is meant to improve outcomes. These outcomes have been measured by Length Of Stay (LOS), rate of infection, days on ventilator, etc. Unfortunately, the adaptation of modern technology to accomplish this has been slow in coming. Ever since Shoemaker described in 1988 using a pulmonary artery catheter (PAC) to guide fluid and inotropic administration to deliver supranormal tissue oxygenation, many authors have written about different techniques to achieve this "hemodynamic optimization". Since the PAC and CVC have both gone out of favor for utilization to monitor and improve hemodynamics, many clinicians have resorted using the easy to use static measurements of blood pressure (BP), heart rate (HR), and urine output. In this paper, the authors will review why these static measurements are no longer adequate and review some of the newer technology that have been studied and proven useful. This review of newer technologies combined with laboratory measurements that have also proven to help guide the clinician, may provide the impetus to adopt new strategies in the operating rooms (OR) and SICU.

Systematic review and meta-analysis of oesophageal Doppler-guided fluid management in colorectal surgery

BACKGROUND

Oesophageal Doppler monitor (ODM)-guided fluid therapy has been recommended for routine use in patients undergoing colorectal surgery. However, recent trials have suggested either equivalent or inferior results for patients randomized to ODM-guided fluid management, especially when compared with fluid restriction or within the context of optimized perioperative care. Hence, an updated systematic review and meta-analysis was conducted.

METHODS

A systematic review and meta-analysis was conducted of all randomized trials exploring ODM-guided fluid management in major colorectal surgery with the endpoints total complications and length of hospital stay (LOS). Subset analyses were planned a priori specifically to investigate the role of the ODM in the context of fluid restriction or optimized perioperative care.

RESULTS

Six high-quality trials comprising a total of 691 patients were included in the final analysis. ODM-guided fluid therapy did not influence the incidence of complications (odds ratio 0·74, 95 per cent confidence interval (c.i.) 0·50 to 1·11; P = 0·15), with moderate heterogeneity in the results (I(2)  = 33 per cent; P = 0·19). There was no difference in mean LOS between patients receiving ODM-guided fluid therapy and controls: mean difference -0·88 (95 per cent c.i. -2·89 to 1·13) days (P = 0·39). There was no difference in complications or LOS when ODM-guided fluid therapy was compared with fluid restriction or used within an otherwise optimized perioperative environment.

CONCLUSION

ODM-guided fluid therapy did not influence LOS or complications in patients undergoing colorectal surgery. Results favouring the ODM were seen only in early studies, whereas newer trials did not show any benefit from such monitoring.

The pathophysiology of fluid and electrolyte balance in the older adult surgical patient

BACKGROUND & AIMS

Age-related physiological changes predispose even the healthy older adult to fluid and electrolyte abnormalities which can cause morbidity and mortality. The aim of this narrative review is to highlight key aspects of age-related pathophysiological changes that affect fluid and electrolyte balance in older adults and underpin their importance in the perioperative period.

METHODS

The Web of Science, MEDLINE, PubMed and Google Scholar databases were searched using key terms for relevant studies published in English on fluid balance in older adults during the 15 years preceding June 2013. Randomised controlled trials and large cohort studies were sought; other studies were used when these were not available. The bibliographies of extracted papers were also searched for relevant articles.

RESULTS

Older adults are susceptible to dehydration and electrolyte abnormalities, with causes ranging from physical disability restricting access to fluid intake to iatrogenic causes including polypharmacy and unmonitored diuretic usage. Renal senescence, as well as physical and mental decline, increase this susceptibility. Older adults are also predisposed to water retention and related electrolyte abnormalities, exacerbated at times of physiological stress. Positive fluid balance has been shown to be an independent risk factor for morbidity and mortality in critically ill patients with acute kidney injury.

CONCLUSIONS

Age-related pathophysiological changes in the handling of fluid and electrolytes make older adults undergoing surgery a high-risk group and an understanding of these changes will enable better management of fluid and electrolyte therapy in the older adult.

A comparison of noninvasive bioreactance with oesophageal Doppler estimation of stroke volume during open abdominal surgery: an observational study

CONTEXT

The anaesthetist must maintain tissue perfusion by ensuring optimal perioperative fluid balance. This can be achieved using less invasive cardiac output monitors such as oesophageal Doppler monitoring (ODM). Other less invasive cardiac output monitors using bio-impedence technology (noninvasive cardiac output monitoring, NICOM) may have a role in monitoring the circulation and informing fluid management decisions.

OBJECTIVE

To compare estimates of stroke volume from ODM with those from NICOM, a noninvasive monitor using bioreactance, a modification of transthoracic bio-impedence.

DESIGN

An observational study.

SETTING

Manchester Royal Infirmary, UK. Data collected in 2011 and 2012.

PARTICIPANTS

Twenty-two patients scheduled for major, open abdominal surgery. Reasons for noninclusion: atrial fibrillation; heart failure; oesophageal disease; lack of capacity; and known sensitivity to colloid.

INTERVENTION

All patients had oesophageal Doppler cardiac output monitoring as a standard element of anaesthesia care. We placed NICOM Bioreactance electrodes and recorded stroke volume estimates from both devices. Fluid challenges were given by the anaesthetist and the haemodynamic responses were recorded.

MAIN OUTCOME MEASURE

Stroke volume during surgery. The Bland-Altman method was used to compare bias and limits of agreement for stroke volume and cardiac output. Fluid responders were defined as patients who increased stroke volume by at least 10% after fluid loading. The precision of each device was calculated during periods of haemodynamic stability.

RESULTS

We made 788 acceptable measurements of cardiac output. The bias was -6.9 ml and the limits of agreement were -22.9 to 36.8 ml. The percentage error was 57%. Average precision for both the ODM and NICOM were similar, 8.5% (SD 5.4%) and 8.7% (SD 3.2%). The concordance for the stroke volume change following fluid challenge was 90.5%. Both devices produced unacceptable readings with electrical diathermy.

CONCLUSION

Simultaneous stroke volume estimations made by noninvasive Bioreactance (NICOM) and oesophageal Doppler showed bias and limits of agreement that are not clinically acceptable. The measurements made by these two devices cannot be regarded as interchangeable.