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

Comparison of central and mixed venous saturation during liver transplantation in cirrhotic patients: a pilot study

BACKGROUND AND OBJECTIVE

Liver transplantation is associated with important haemodynamic variations requiring cardiac output and oximetric data monitoring. The mixed venous saturation (SvO2) integrates parameters combining information about oxygen consumption, cardiac output and haemoglobin concentration. Central venous saturation (ScvO2) can be directly measured from blood drawn in the superior venous system via a central venous catheter. ScvO2 has been proposed as an alternative to SvO2 for intraoperative haemodynamic monitoring. The aim of the present study was to examine the level of agreement between SvO2 and ScvO2 during the preanhepatic and the neohepatic stage of liver transplantation in cirrhotic patients.

MATERIALS AND METHODS

After agreement from the regulatory authorities for medical research and having obtained informed consent, 30 patients with cirrhosis undergoing liver transplantation were prospectively included. Blood gas samples were simultaneously drawn from the arterial line, the right atrium port and the pulmonary artery port of the catheter: during the preanhepatic stage (two times) and two times 30-40 min after graft revascularization. Arterial saturation (SaO2), haemoglobin concentration, cardiac index, SvO2, ScvO2 and oxygen consumption, delivery and extraction (VO2, DO2 and EO2, respectively) were measured. A Bland-Altman test was used to determine bias and limits of agreement between SvO2 and ScvO2. Both parameters were considered to be equivalent if limits of agreement were within +/-5%.

RESULTS

Bland-Altman analysis revealed a bias (limit of agreement) of -1.2% (-9.1 to 6.6%), -0.3% (-4.8 to 4%) and -2.1% (-12 to 7.8%) for the overall measurements and preanhepatic and postgraft reperfusion measurements, respectively. SvO2 decreased significantly between hepatectomy and reperfusion, whereas cardiac index, VO2, DO2 and EO2 showed significantly higher values after reperfusion. ScvO2 and SaO2 levels did not display different values between the two periods.

DISCUSSION

Measurements of SvO2 and ScvO2 showed a good level of agreement during the preanhepatic stage, whereas the level of agreement was low after liver graft reperfusion. The increase of VO2 associated with the decrease of SvO2 and the stability of ScvO2 between the two periods suggest an incomplete mixing of splanchnic venous blood into the right atrium. In addition, our samples were taken from the right atrium, which is not possible using a conventional central venous catheter, as the tip must lie in the superior vena cava and not in the right atrium. ScvO2 cannot be considered equivalent to SvO2 for the haemodynamic monitoring of patients with cirrhosis undergoing liver transplantation.

Oesophageal Doppler-guided fluid administration in colorectal surgery: critical appraisal of published clinical trials

The evidence underpinning oesophageal Doppler monitoring (ODM)-guided fluid administration in colorectal surgery has not been critically appraised despite quantitative meta-analyses. A qualitative systematic review of the methodology and findings of all published randomised-controlled trials (RCTs) exploring ODM-guided fluid administration in major abdominal surgery was conducted. Four, well-designed single-centre trials inclusive of 393 patients in total have primarily demonstrated that ODM-guided intraoperative fluid administration decreases hospital length of stay (LOS) and complications by optimising intraoperative cardiac parameters. One subsequently published RCT shows that ODM-guided fluid administration predisposes to a greater LOS and significantly increased complications. However, all the trials have been hampered by imprecise definitions with heterogeneity in patient selection, intraoperative fluid administration strategies and methods of outcome assessment. ODM-guided fluid administration has only been investigated in the setting of laparoscopic colonic surgery and within an optimised perioperative care protocol in one trial, where it was not shown to be beneficial. Nevertheless, it was recommended for use in this context before the trial was even published. ODM-guided fluid administration has not been compared with intraoperative fluid restriction. Current evidence regarding the use of Doppler-guided fluid administration is limited by heterogeneity in the trial design, and the initial clinical benefits observed may be largely offset by recent advances in surgical techniques and perioperative care.

Maintaining tissue perfusion in high-risk surgical patients: a systematic review of randomized clinical trials

BACKGROUND

Surgical patients with limited organic reserve are considered high-risk patients and have an increased perioperative mortality. For this reason, they need a more rigorous perioperative protocol of hemodynamic control to prevent tissue hypoperfusion. In this study, we systematically reviewed the randomized controlled clinical trials that used a hemodynamic protocol to maintain adequate tissue perfusion in the high-risk surgical patient.

METHODS

We searched MEDLINE, Embase, LILACS, and Cochrane databases to identify randomized controlled clinical studies of surgical patients studied using a perioperative hemodynamic protocol of tissue perfusion aiming to reduce mortality and morbidity; the latter characterized at least one dysfunctional organ in the postoperative period. Pooled odds ratio (POR) and 95% confidence interval (CI) were calculated for categorical outcomes.

RESULTS

Thirty-two clinical trials were selected, comprising 5056 high-risk surgical patients. Global meta-analysis showed a significant reduction in mortality rate (POR: 0.67; 95% CI: 0.55-0.82; P < 0.001) and in postoperative organ dysfunction incidence (POR: 0.62; 95% CI: 0.55-0.70; P < 0.00,001) when a hemodynamic protocol was used to maintain tissue perfusion. When the mortality rate was >20% in the control group, the use of a hemodynamic protocol to maintain tissue optimization resulted in a further reduction in mortality (POR: 0.32; 95% CI: 0.21-0.47; P < 0.00,001). Monitoring cardiac output with a pulmonary artery catheter and increasing oxygen transport and/or decreasing consumption also significantly reduced mortality (POR: 0.67; 95% CI: 0.54-0.84; P < 0.001 and POR: 0.71; 95% CI: 0.57-0.88; P < 0.05, respectively). Therapy directed at increasing mixed or central venous oxygen saturation did not significantly reduce mortality (POR: 0.68; 95% CI: 0.22-2.10; P > 0.05). The only study using lactate as a marker of tissue perfusion failed to demonstrate a statistically significant reduction in mortality (OR: 0.33; 95% CI: 0.07-1.65; P > 0.05).

CONCLUSIONS

In high-risk surgical patients, the use of a hemodynamic protocol to maintain tissue perfusion decreased mortality and postoperative organ failure. Monitoring cardiac output calculating oxygen transport and consumption helped to guide therapy. Additional randomized controlled clinical studies are necessary to analyze the value of monitoring mixed or central venous oxygen saturation and lactate in high-risk surgical patients.

Anesthesia and outcome after partial hepatectomy for adult-to-adult donor transplantation

PURPOSE OF REVIEW

The worldwide adoption of live liver donors as a source of donor organs for transplantation has been curtailed by the very real risk of complications in otherwise healthy people. Our objective in this review is to outline the perioperative management of the live liver donor for adult-to-adult transplantation.

RECENT FINDINGS

The incidence and severity of complications following live liver donation is extremely variable, and reporting needs to be standardized if we are to improve the perioperative management and outcomes. Agreed definitions would clarify the incidence and severity of postoperative complications, allow identification of areas in which management can be improved and suggest areas for future investigation. Such an effort will require the cooperation of centers around the world.

SUMMARY

Live liver donation is a valuable option for organ donation that can be conducted safely with a multidisciplinary perioperative approach. Future considerations should focus on the recovery period and how the intraoperative management can be optimized to minimize the impact of surgery on donors' quality of life.

Improving surgical outcomes: it is the destination not the journey

Studies have demonstrated that optimising the circulating volume reduces morbidity after major surgery. This optimisation is usually achieved through maximisation of the stroke volume guided by oesophageal Doppler. New monitoring parameters of preload responsiveness using information from the arterial trace are now showing some promise in achieving the same goal. The present commentary examines these new parameters with respect to improving outcomes for the high-risk surgical patient.

Normovolemia defined according to cardiac stroke volume in healthy supine humans

BACKGROUND

Both hypovolemia and a fluid overload are detrimental for outcome in surgical patients but the effort to establish normovolemia is hampered by the lack of an operational clinical definition. Manipulating the central blood volume on a tilt table demonstrates that the flat part of the Frank-Starling curve is reached when subjects are supine and that finding may be applicable for a clinical definition of normovolemia. However, it is unknown whether stroke volume (SV) responds to an increase in preload induced by fluid administration.

METHODS

In 20 healthy subjects (23 +/- 2 years, mean +/- SD), SV was measured by esophageal Doppler before and after fluid administration to evaluate whether SV increases in healthy, non-fasting, supine subjects. Two hundred millilitres of a synthetic colloid (hydroxyethyl starch, HES 130/0.4) was provided and repeated if a >or=10% increment in SV was obtained.

RESULTS

None of the subjects increased SV >or=10% following fluid administration but there was a minor increase in mean arterial pressure (92 +/- 15 to 93 +/- 12 mmHg, P = 0.01), while heart rate (HR) (66 +/- 12 beats min(-1); P = 0.32), cardiac output (4.8 +/- 1.1 l min(-1); P = 0.25) and the length of the systole corrected to a HR of 60 beats/min (corrected flow time; 344 +/- 24 ms; P = 0.31) did not change.

CONCLUSION

Supporting the proposed definition of normovolemia, non-fasting, supine, healthy subjects are provided with a preload to the heart that does not limit SV suggesting that the upper flat part of the Frank-Starling relationship is reached.

A meta-analysis of randomised controlled trials of intravenous fluid therapy in major elective open abdominal surgery: getting the balance right

The terminology used for describing intervention groups in randomised controlled trials (RCT) on the effect of intravenous fluid on outcome in abdominal surgery has been imprecise, and the lack of standardised definitions of the terms 'standard', 'restricted' and 'liberal' has led to some confusion and difficulty in interpreting the literature. The aims of this paper were to clarify these definitions and to use them to perform a meta-analysis of nine RCT on primarily crystalloid-based peri-operative intravenous fluid therapy in 801 patients undergoing elective open abdominal surgery. Patients who received more or less fluids than those who received a 'balanced' amount were considered to be in a state of 'fluid imbalance'. When 'restricted' fluid regimens were compared with 'standard or liberal' fluid regimens, there was no difference in post-operative complication rates (risk ratio 0.83 (95% CI 0.49, 1.39, P = 0.47) [corrected] or length of hospital stay (weighted mean difference (WMD) - 1.77 (95% CI - 4.36, 0.81) d, P = 0.18). However, when the fluid regimens were reclassified and patients were grouped into those who were managed in a state of fluid 'balance' or 'imbalance', the former group had significantly fewer complications (risk ratio 0·59 (95% CI 0·44, 0·81), P=0·0008) and a shorter length of stay (WMD -3·44 (95% CI -6·33, -0·54) d, P=0·02) than the latter. Using imprecise terminology, there was no apparent difference between the effects of fluid-restricted and standard or liberal fluid regimens on outcome in patients undergoing elective open abdominal surgery. However, patients managed in a state of fluid balance fared better than those managed in a state of fluid imbalance.

Functional intravascular volume deficit in patients before surgery

BACKGROUND

Stroke volume (SV) maximization with a colloid infusion, referred to as individualized goal-directed therapy, improves outcome in high-risk surgery. The fraction of patients who need intravascular volume to establish a maximal SV has, however, not been evaluated, and there are only limited data on the volume required to establish a maximal SV before the start of surgery. Therefore, we estimated the occurrence and size of the potential functional intravascular volume deficit in surgical patients.

METHODS

Patients scheduled for mastectomy (n=20), open radical prostatectomy (n=20), or open major abdominal surgery (n=20) were anaesthetized, and before the start of surgery, a 200 ml colloid fluid challenge was provided and repeated if a >or=10% increment in SV estimated by oesophageal Doppler was established. The volume needed for SV maximization defined the intravascular volume deficit.

RESULTS

Forty-two (70%) of the patients needed volume to establish a maximal SV. For the patients needing volume, the required amount was median 200 ml (range 200-600 ml), with no significant difference between the three groups of patients. The required volume was >or=400 ml in nine patients (15%).

CONCLUSION

The majority of anaesthetized patients present with a functional intravascular volume deficit before surgery. Although the deficit in general was minor, a fraction of patients presented with a deficit that may be of clinical relevance, emphasizing the importance of the individual approach of goal-directed fluid therapy.

Choosing patient-tailored hemodynamic monitoring

This article is one of ten reviews selected from the Yearbook of Intensive Care and Emergency Medicine 2010 (Springer Verlag) and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/yearbook. Further information about the Yearbook of Intensive Care and Emergency Medicine is available from http://www.springer.com/series/2855.

Goal-directed intraoperative therapy based on autocalibrated arterial pressure waveform analysis reduces hospital stay in high-risk surgical patients: a randomized, controlled trial

Introduction

Several studies have shown that goal-directed hemodynamic and fluid optimization may result in improved outcome. However, the methods used were either invasive or had other limitations. The aim of this study was to perform intraoperative goal-directed therapy with a minimally invasive, easy to use device (FloTrac/Vigileo), and to evaluate possible improvements in patient outcome determined by the duration of hospital stay and the incidence of complications compared to a standard management protocol.

Methods

In this randomized, controlled trial 60 high-risk patients scheduled for major abdominal surgery were included. Patients were allocated into either an enhanced hemodynamic monitoring group using a cardiac index based intraoperative optimization protocol (FloTrac/Vigileo device, GDT-group, n = 30) or a standard management group (Control-group, n = 30), based on standard monitoring data.

Results

The median duration of hospital stay was significantly reduced in the GDT-group with 15 (12 - 17.75) days versus 19 (14 - 23.5) days (P = 0.006) and fewer patients developed complications than in the Control-group [6 patients (20%) versus 15 patients (50%), P = 0.03]. The total number of complications was reduced in the GDT-group (17 versus 49 complications, P = 0.001).

Conclusions

In high-risk patients undergoing major abdominal surgery, implementation of an intraoperative goal-directed hemodynamic optimization protocol using the FloTrac/Vigileo device was associated with a reduced length of hospital stay and a lower incidence of complications compared to a standard management protocol.

Trial Registration

Clinical trial registration information: Unique identifier: NCT00549419

Emerging trends in minimally invasive haemodynamic monitoring and optimization of fluid therapy

BACKGROUND

For decades the pulmonary artery catheter has been the mainstay of cardiac output monitoring in critically ill patients, and pressure-based indices of ventricular filling have been used to gauge fluid requirements with acknowledged limitations. In recent years, alternative technologies have become available which are minimally invasive, allow beat-to-beat cardiac output monitoring and permit assessment of fluid requirements by volumetric means and by allowing assessment of heart-lung interaction in mechanically ventilated patients.

METHODS

A qualitative review of the basic science behind the transpulmonary dilution technique used in the measurement of cardiac output, global end-diastolic volume and extravascular lung water; the basic science and validation of pulse contour analysis methods of real-time cardiac output monitoring; the application and limitations of these technologies to guide rational fluid therapy in surgical and critically ill patients.

RESULTS

Transpulmonary dilution techniques correlate well with pulmonary artery catheter-derived measurement of cardiac output. Volumetric measures of preload appear to be superior to central venous and pulmonary artery occlusion pressures. Dynamic indices of preload responsiveness such as stroke volume variation are more useful than static measures in mechanically ventilated patients.

CONCLUSION

In fully mechanically ventilated patients, dynamic measurements of heart-lung interaction such as stroke volume variation are superior to static measures of preload in assessing whether a patient is volume-responsive (i.e. will increase stroke volume in response to a fluid challenge). For patients who are not fully mechanically ventilated, pulse contour analysis allows real-time assessment of increases in cardiac output in response to passive leg-raising.

Latest developments in peri-operative monitoring of the high-risk major surgery patient

Peri-operative monitoring technology has made great strides in the last 20 years with the introduction of minimally invasive devices to measure inter alia stroke volume, cardiac output, depth of anaesthesia and cerebral and tissue oxygen monitoring. Despite these technological advances, peri-operative management of the high risk major surgery patient has remained virtually unchanged. The vast majority of patients undergo a pre-operative assessment which is neither designed to quantify functional capacity nor predict outcome. Anaesthetists then usually monitor these patients using the same technology (e.g. pulse oximetry (SpO2), invasive systemic BP and CVP, end tidal carbon dioxide (etCO2) and anaesthetic agent monitoring) that was available in the early 1980s. Conventional intra-operative management can result in occult low levels of blood flow and oxygen delivery that lead to complications that only occur days or weeks following surgery and give false re-assurance to the anaesthetist that he or she is doing a "good job". Post-operative management then often takes place in an environment with reduced levels of both monitoring equipment and staff expertise. It is perhaps not surprising that outcome still remains poor in high-risk patients.(1) In this review, we will briefly describe the role of peri-operative optimization, some of the available monitors and indicate how their combined use might be beneficial in managing the high-risk surgical patient. We believe that although there is now evidence to suggest that the use of individual new monitors (such as assessment of fluid status, depth of anaesthesia, tissue oxygenation and blood flow) can influence outcome, it will only be their combination that will radically improve the peri-operative management and outcome of high-risk surgical patients. It is a matter of some urgency that large scale, prospective and collaborative studies be designed, funded and executed to prove or disprove this hypothesis.

Anesthetic management of acute mesenteric ischemia in elderly patients

Ischemic insult to the splanchnic vasculature can jeopardize bowel viability and lead to devastating consequences, including bowel necrosis and gangrene. Although acute mesenteric ischemia (AMI) may occur at any age, the elderly are most commonly affected due to their higher incidence of underlying systemic pathology, most notably atherosclerotic cardiovascular disease. Treatment options include pharmacology-based actions, endovascular, and surgical interventions. AMI remains a life-threatening condition with a mortality rate of 60% to 80%, especially if intestinal infarction has occurred and surgical intervention becomes emergent. Early recognition and an aggressive therapeutic approach are essential if the usually poor outcome is to be improved. Anesthetic management is complex and must account for comorbid disease as well as the patient's presumptive acute deterioration. Blood pressure support typically involves careful, but often massive, fluid resuscitation and may also additionally require pharmacologic support.

Goal-directed haemodynamic therapy and gastrointestinal complications in major surgery: a meta-analysis of randomized controlled trials

Postoperative gastrointestinal (GI) dysfunction is one of the most frequent complications in surgical patients. Most cases are associated with episodes of splanchnic hypoperfusion due to hypovolaemia or cardiac dysfunction. It has been suggested that perioperative haemodynamic goal-directed therapy (GDT) may reduce the incidence of these complications in cardiac surgery, and other surgery, but clear evidence is lacking. We have undertaken a meta-analysis of the effects of GDT on postoperative GI and liver complications. A systematic search, using MEDLINE, EMBASE, and The Cochrane Library databases, was performed. Sixteen randomized controlled trials (3410 participants) met the inclusion criteria. Data synthesis was obtained using odds ratio (OR) with 95% confidence interval (CI) by random-effects model. Statistical heterogeneity was assessed by Q and I2 statistics. GI complications were ranked as major (required radiological or surgical intervention or life-threatening condition) or minor (no or only pharmacological treatment required). Major GI complications were significantly reduced by GDT when compared with a control group (OR, 0.42; 95% CI, 0.27-0.65). Minor GI complications were also significantly decreased in the GDT group (OR, 0.29; 95% CI, 0.17-0.50). Treatment did not reduce hepatic injury rate (OR, 0.54; 95% CI, 0.19-1.55). Quality sensitive analyses confirmed the main overall results. In patients undergoing major surgery, GDT, by maintaining an adequate systemic oxygenation, can protect organs particularly at risk of perioperative hypoperfusion and is effective in reducing GI complications.

Clinical review: Goal-directed therapy in high risk surgical patients

A small group of patients account for the majority of peri-operative morbidity and mortality. These 'high-risk' patients have a poor outcome due to their inability to meet the oxygen transport demands imposed on them by the nature of the surgical response during the peri-operative period. It has been shown that by targeting specific haemodynamic and oxygen transport goals at any point during the peri-operative period, the outcomes of these patients can be improved. This goal directed therapy includes the use of fluid loading and inotropes, in order to optimize the preload, contractility and afterload of the heart whilst maintaining an adequate coronary perfusion pressure. Despite the benefits seen, it remains a challenge to implement this management due to difficulties in identifying these patients, scepticism and lack of critical care resources.

'Liberal' vs. 'restrictive' perioperative fluid therapy--a critical assessment of the evidence

BACKGROUND

Several studies have assessed the effect of a 'liberal' vs. a 'restrictive' perioperative fluid regimen on post-operative outcome. The literature was reviewed in order to provide recommendations regarding perioperative fluid regimens.

METHODS

A PubMed search identified randomized clinical trials and cited studies, comparing two different fixed fluid volumes on post-operative clinical outcome in major surgery. Studies were assessed for the type of surgery, primary and secondary outcome endpoints, the type and volume of administered fluid and the definition of the perioperative period. Also, information regarding perioperative care and type of anaesthesia was assessed.

RESULTS

In the seven randomized studies identified, the range of the liberal intraoperative fluid regimen was from 2750 to 5388 ml compared with 998 to 2740 ml for the restrictive fluid regimen. The period for fluid therapy and outcome endpoints were inconsistently defined and only two studies reported perioperative care principles and discharge criteria. Three studies found an improved outcome (morbidity/hospital stay) with a restrictive fluid regimen whereas two studies found no difference and two studies found differences in the selected outcome parameters.

CONCLUSION

Liberal vs. restrictive fixed-volume regimens are not well defined in the literature regarding the definition, methodology and results, and lack the use of or information on evidence-based standardized perioperative care-principles (fast-track surgery), thereby precluding evidence-based guidelines for procedure-specific perioperative fixed-volume regimens. Optimization of perioperative fluid management may include a combination of fixed crystalloid administration to replace extra-vascular losses and avoiding fluid excess, together with individualized goal-directed colloid administration to maintain a maximal stroke volume.

Perioperative hemodynamic monitoring with transesophageal Doppler technology

Invasive cardiac output (CO) monitoring, traditionally performed with transpulmonary thermodilution techniques, is usually reserved for high-risk patients because of the inherent risks of these methods. In contrast, transesophageal Doppler (TED) technology offers a safe, quick, and less invasive method for routine measurements of CO. After esophageal insertion and focusing of the probe, the Doppler beam interrogates the descending aortic blood flow. On the basis of the measured frequency shift between the emitted and received ultrasound frequency, blood flow velocity is determined. From this velocity, combined with the simultaneously measured systolic ejection time, CO and other advanced hemodynamic variables can be calculated, including estimations of preload, afterload, and contractility. Numerous studies have validated TED-derived CO against reference methods. Although the agreement of CO values between TED and the reference methods is limited (95% limits of agreement: median 4.2 L/min, interquartile range 3.3-5.0 L/min), TED has been shown to accurately follow changes of CO over time, making it a useful device for trend monitoring. TED can be used to guide perioperative intravascular volume substitution and therapy, with vasoactive or inotropic drugs. Various studies have demonstrated a reduced postoperative morbidity and shorter length of hospital stay in patients managed with TED compared with conventional clinical management, suggesting that it may be a valuable supplement to standard perioperative monitoring. We review not only the technical basis of this method and its clinical application but also its limitations, risks, and contraindications.

Systematic review of oxidative stress associated with pneumoperitoneum

Background

There have been several reports of ischaemic complications after routine laparoscopy. The aim of this review was to investigate the relationship between this oxidative stress and pneumoperitoneum.

Methods

Medline, Medline in-process, The Cochrane Library, PubMed and EMBASE were searched for papers on oxidative stress and pneumoperitoneum, from 1947 to March 2008 with no language restriction or restriction on trial design. Papers that did not investigate pneumoperitoneum as a causative factor, or did not report outcome measures related to oxidative stress, were excluded.

Results

A total of 73 relevant papers were identified: 36 animal studies, 21 human clinical trials, nine case reports, five review articles and two comments. Pneumoperitoneum causes a reduction in splanchnic blood flow, resulting in biochemical evidence of oxidative stress in a pressure- and time-dependent manner. There is evidence that the use of carbon dioxide for insufflation is contributory. Several measures proposed to minimize the oxidative stress have shown promise in animal studies, but few have been evaluated in the clinical setting.

Conclusion

There is an increasing body of evidence, mainly from animal studies, that pneumoperitoneum decreases splanchnic perfusion with resulting oxidative stress. It is now appropriate to investigate the clinical significance of pneumoperitoneum-associated oxidative stress.

Perioperative fluid retention and clinical outcome in elective, high-risk colorectal surgery

BACKGROUNDS AND AIMS

There is some controversy regarding concepts currently propagated for an optimal perioperative fluid management in colorectal surgery. We wanted to analyze the association of net intraoperative and postoperative fluid balances with postoperative morbidity and length of stay.

MATERIALS AND METHODS

We performed a retrospective analysis of data collected prospectively from March 1993 through February 2005. A subgroup from 4,658 patients was studied who had undergone major elective colorectal surgery during that time. This subgroup included 198 patients with a particularly high preoperative risk profile requiring immediate postoperative intensive care unit (ICU) admission. Fluid therapy was guided by established clinical end points. Results were adjusted for various confounding variables (extent of the operative trauma, individual response to the injury, type of analgesia, underlying disease, treatment era).

RESULTS/FINDINGS

After adjustment for relevant covariates, the magnitude of fluid balance was unimportant for morbidity and postoperative hospital length of stay. A high Apache II score after ICU admission, an increased perioperative blood loss, and palliative surgical procedures were associated with a significantly higher complication rate, whereas use of epidural analgesia improved morbidity and shortened hospital stay.

INTERPRETATION/CONCLUSION

If guided by established standards, even large perioperative fluid retentions do not appear to be associated with a worse outcome after extended colorectal surgery. Epidural analgesia may provide a significant benefit in those high-risk patients.

Plasma volume expanders and intraoperative fluid therapy

Adequate restoration of intravascular volume remains an important therapeutic maneuver in managing the surgical patient. Definition of the ideal volume replacement strategy still remains one of the burning problems. Firstly, the choice between colloid and crystalloid solutions continues to generate controversy. Secondly, the highly controversial crystalloid/colloid dispute has been enlarged to a colloid/colloid debate because of the increasing number of colloids that are available. And lastly, whether high or low volume replacement strategies are favorable for the surgical patient is an another issue for the anesthesiologists. Volume replacement has been hitherto often based on art, dogma and personal beliefs. It was the aim of this overview to present the different solutions and to facilitate the strategies for above three main issues in the field of intraoperative fluid therapy.