Oesophageal Doppler Monitoring Research Articles

Which goal for fluid therapy during colorectal surgery is followed by the best outcome: near-maximal stroke volume or zero fluid balance?

We aimed to investigate whether fluid therapy with a goal of near-maximal stroke volume (SV) guided by oesophageal Doppler (ED) monitoring result in a better outcome than that with a goal of maintaining bodyweight (BW) and zero fluid balance in patients undergoing colorectal surgery. In a double-blinded clinical multicentre trial, 150 patients undergoing elective colorectal surgery were randomized to receive fluid therapy after either the goal of near-maximal SV guided by ED (Doppler, D group) or the goal of zero balance and normal BW (Zero balance, Z group). Stratification for laparoscopic and open surgery was performed. The postoperative fluid therapy was similar in the two groups. The primary endpoint was postoperative complications defined and divided into subgroups by protocol. Analysis was performed by intention-to-treat. The follow-up was 30 days. The trial had 85% power to show a difference between the groups. The number of patients undergoing laparoscopic or open surgery and the patient characteristics were similar between the groups. No significant differences between the groups were found for overall, major, minor, cardiopulmonary, or tissue-healing complications (P-values: 0.79; 0.62; 0.97; 0.48; and 0.48, respectively). One patient died in each group. No significant difference was found for the length of hospital stay [median (range) Z: 5.00 (1-61) vs D: 5.00 (2-41); P=0.206]. Goal-directed fluid therapy to near-maximal SV guided by ED adds no extra value to the fluid therapy using zero balance and normal BW in patients undergoing elective colorectal surgery.

Intra‐operative oxygen delivery in infusion volume‐optimized patients undergoing laparoscopic colorectal surgery within an enhanced recovery programme: the effect of different analgesic modalities

Patients undergoing major open surgery who have an indexed oxygen delivery (DO(2) I) > 600 ml/min/m(2) have been shown to have a lower incidence of morbidity and mortality compared with those whose DO(2) I is below this level. Laparoscopy and Trendelenburg positioning cause a reduction in DO(2) I. We aimed to quantify the effect of the type of analgesia on DO(2) I and to correlate the DO(2) I achieved with the incidence of anastomotic leakage in patients undergoing laparoscopic surgery. Following ethical approval, patients were randomized to receive spinal anaesthesia (Group S), epidural analgesia (Group E) or intravenous morphine (Group P) followed by postoperative patient-controlled analgesia (PCA). In addition to standard monitoring, oesophageal Doppler monitoring of the stroke volume allowed directed intravenous fluid therapy. The mean DO(2) I was compared with the anastomotic leakage rate. Seventy-five patients were recruited (Group S, 27; Group E, 23; Group P, 25). The mean (range) DO(2) I for all patients was 490 (230-750) ml/min/m(2) . The analgesic modality had no effect on DO(2) I. Of the 18 patients with a DO(2) I of < 400 ml/min/m(2) , four (22%) developed anastomotic leakage compared with one (%) of the 57 patients with a DO(2) I of > 400 ml/min/m(2) (P = 0.01). The analgesic modality used had no effect on the DO(2) I achieved. Anastomotic leakage was significantly higher in patients with a DO(2) I of < 400 ml/min/m(2) . A further study assessing the outcome after raising the DO(2) I with inotropes is required.

Descending aortic blood flow during aortic cross-clamp indicates postoperative splanchnic perfusion and gastrointestinal function in patients undergoing aortic reconstruction

The purpose of this observational study was to investigate the relationship between splanchnic and renal blood flow during infrarenal aortic cross-clamp (XC) and postoperative gastrointestinal perfusion and function. Descending aortic blood flow (DABF) was continuously monitored with an oesophageal Doppler monitor (Cardio-Q, Deltex Ltd, Chichester, UK) in 31 patients undergoing elective abdominal aortic aneurysm repair. Cardiac output (CO) was determined by indocyanine green dilution before, during, and after XC. Perioperative gastrointestinal perfusion was assessed by gastric intramucosal pH (pHi, Tonocap, GE Healthcare, Helsinki, Finland). Postoperative gastrointestinal recovery was assessed by the number of postoperative days until the patient successfully resumed solid food intake. The relationship between the mean DABF during XC and gastric pHi after XC release and postoperative gastrointestinal recovery was analysed with Spearman's correlation coefficient. accounted for ∼ 55% of CO during XC and significantly decreased during XC, despite arterial pressure remaining within an optimal range. There were two distinct relationships between DABF during XC and gastric pHi after XC release. Gastric pHi steeply and linearly declined when indexed DABF was below 0.82 litre min(-1) m(-2). Above this critical value, there was no linear relationship between them. The duration of postoperative gastrointestinal dysfunction was inversely correlated with the mean DABF during XC. The best cut-off value of the mean indexed DABF during XC to prevent prolonged gastrointestinal dysfunction was 1.2 litre min(-1) m(-2). Decreased DABF during XC associates splanchnic hypoperfusion after XC release and delayed recovery of gastrointestinal function.

Oesophageal Doppler monitoring: a misguided editorial

Ghosh and colleagues raise a series of concerns regarding the guidelines from the National Institute for Health and Clinical Excellence (NICE) on the use of the oesophageal Doppler monitor (ODM) [1]. Firstly, they state the current evidence base is insufficient to justify publication of the guideline, although it has recently been added to regarding major urology surgery [2]. No guideline is perfect, and many treatments in current practice have an imperfect evidence base – one estimate is that 50% of clinical practice guidelines are opinion- rather than evidence-based [3]. The question that Ghosh et al. should address, therefore, is ‘how much evidence is enough?’ The level of evidence for the use of the ODM is greater than for high frequency oscillatory ventilation, extracorporeal membrane oxygenation, and inotropes in heart failure, not to mention other common interventions in anaesthesia and critical care. We live in an imperfect, uncertain world, and waiting for ‘perfect evidence’ risks decision-making stasis. Their second concern relates to links between industry and experts. In general, this is a valid concern, but the apparently dichotomous view that ‘industry link = bad, non-industry link = good’ is, we feel, naive. Most commentators are biased in one way or another [4, 5]. Thirdly, their view appears to be that guidelines should not be produced for specific technologies unless a similar level of information is available for competitor devices. In this case, the comparator is generally ‘current accepted practice’ rather than other cardiac output monitors. The lack of evidence from other devices is not relevant in this instance; indeed, it is consistently the case that despite NICE guidance, use of ODM or similar technologies remains low (personal observation). Such studies of other monitors against ODM are certainly valid, but we doubt that ethics committees would allow a control arm where stroke volume was not estimated and managed; equivalence studies are probably all that would be allowed. Ghosh et al. also suggest that one result of NICE guidance is an inappropriate pressure on managers and clinicians to adopt technologies and treatments. The NICE guidance documents do not state that clinicians are obliged to use ODM technology and many such innovations are routinely debated within departments. In many cases, they will choose not to follow specific recommendations for a variety of reasons. Ghosh et al. also express disbelief that a short-lived intervention can save the NHS £1100 per patient. Nevertheless, an unpublished cost analysis of our study [2] demonstrated a saving in excess of £1900 per patient. This came predominantly from a reduction in bed-days and requirement for total parenteral nutrition, due to a reduction in gastrointestinal complications and the number of long-stay patients. It does not come from a reduction in stay in every treated patient. Finally, Ghosh et al. suggest that one should simply dispense with the ODM and give all patients an extra 500 ml colloid bolus. We presume this is a deliberately tongue-in-cheek remark, rather than their belief after reading the available clinical evidence.

Oesophageal Doppler monitoring: evidence and hip surgery

We would like to thank the authors of the editorial published in December’s Anaesthesia [1] highlighting the quality of evidence used in the National Institute for Health and Clinical Excellence (NICE) guidance on oesophageal Doppler monitoring (ODM). While we recognise that minimally-invasive cardiac output monitoring has an important role in careful fluid management in high-risk surgical patients, we too question the singling out of one particular device over a number of commercially available products, considering the quality of evidence used to support its use. A bold statement suggesting a saving of approximately £1100 per patient based on hospital stay by using the CardioQ™ over conventional central venous catheterisation is another worrying point. Venn et al. [2] found that there was a difference in the time until medically fit between patients who had goal directed fluid replacement with ODM guidance compared with the control group. However, they went on to say that they could not show a significant reduction in total hospital stay as there are a number of socio-economical factors that need to be taken into consideration. Sinclair et al. [3] studied the effects of intra-operative fluid management guided by ODM in a small number of patients and found that it corresponded to a shorter hospital stay and therefore could be shown to be cost-efficient. However, Sinclair et al. failed to mention the time lapse between admission and surgery; the pre-operative medical intervention for each patient was not standardised; and the study was conducted in 1997 with the inpatient stay data compared with an in-house audit carried out in 1990-91. We applaud those who conducted this landmark study, but with the design limitations, it is a concern that so much weight was attached to it for the NICE guidance. Patients with fractured femurs are a difficult group to study and many have regional anaesthesia for their surgery. We have found that ODM is particularly difficult to use in awake patients and especially so in those with any cognitive impairment, which accounts for approximately one third of the hip fracture population. Further work is needed on alternative methods of monitoring in this high-risk group of patients.

Oesophageal Doppler monitoring: costly and supported by weak evidence

Oesophageal Doppler monitoring: costly and supported by weak evidence

Oesophageal Doppler monitoring: premature guidance and what about the fluids?

Oesophageal Doppler monitoring: premature guidance and what about the fluids?

Oesophageal Doppler monitoring: the role of NICE

In their editorial, Ghosh et al. are critical of National Institute for Health and Clinical Excellence (NICE) Medical Technology Guidance 3 on CardioQ™ Oesophageal Doppler monitoring, but their description of the facts and their analysis are inaccurate [1]. Medical technologies guidance is different in its context and intent from other NICE publications and it is important that these differences are clearly understood. The NICE medical technologies programme aims to identify technologies that offer advantages to patients and to the service over ‘current management’. Its focus on the claims of specific commercial products (which may have a short market life) is fundamental to developing guidance quickly for the NHS. Moreover, consideration of the issues and uncertainties in the case for adoption of a specific product can help to guide practice in general and the use of other technologies that are claimed to offer similar benefits. Manufacturers notify potential topics; they are not identified by members of the Medical Technologies Advisory Committee (MTAC), which is an advisory body, independent of NICE. The Medical Technologies Advisory Committee is responsible for selecting notified products for which NICE guidance is likely to be of value to the NHS. Submissions are not prepared by NICE’s contracted external assessment centres; these academic centres provide independent critiques of submissions prepared by manufacturers. There is no requirement for hospital trusts to ‘report back to NICE’; medical technology guidance recommends whether trusts should consider adopting technologies, based on clear statements about their likely clinical and cost advantages. Ghosh et al. question the robustness of the evidence base on which the recommendations were made. Evidence for medical devices and diagnostic tests is typically sparse (specifically compared with pharmaceuticals and especially if a technology is relatively new). The NICE medical technologies programme aims to stimulate the development of more and better quality evidence by working with manufacturers and by fostering research. Ghosh et al. criticise manufacturer funding for many of the trials and researchers. It is to the credit of manufacturers when they do fund trials. The Medical Technologies Advisory Committee considers all the features of trial evidence, irrespective of funding source, on the basis of quality, robustness, quantity and potential sources of bias. Ghosh et al. also point out that outcome measures and patient groups were heterogeneous among the available studies; in our experience, this is a common characteristic of clinical evidence, which is why we have developed a deliberative, structured and balanced approach to decision-making. The wide range of clinicians, scientists, lay people and other disciplines on MTAC aims to provide the necessary skills and expertise to weigh evidence and other factors, and to make difficult judgements. The advice of clinical experts is a very important part of the information available to the Committee in making its recommendations. Experts are nominated by stakeholders, including professional societies and manufacturers, and there are robust processes for managing conflicts of interest. We encourage specialist clinicians, including Ghosh and colleagues, to become involved in future medical technology evaluations by seeking to be nominated as experts in their specialty. We would also encourage clinical experts to respond to public consultation, which is a very influential step in the production of NICE guidance.

Usability of Esophageal Doppler for Monitoring of Concealed Retroperitoneal Hemorrhage during Laparoscopy Assisted Subtotal Gastrectomy

Hemodynamic monitoring is an essential element in the management of perioperative patients. In addition, anesthesiologists routinely used blood pressure (invasive or non invasive), heart rate, urinary output and central venous pressure as monitoring modalities. Esophageal doppler monitoring, as a minimally invasive hemodynamic assessment tool, has a good correlation with pulmonary artery catheterization in measuring cardiac output. We experienced a case of concealed retroperitoneal hemorrhage in a patient who underwent a laparoscopic subtotal gastrectomy. When surgeons tried to close trocar sites, the patient's blood pressure dropped rapidly. At laparoscopy, we could not find gross bleeding. However, we could detect hypovolemia by esophageal doppler monitoring (CardioQ, Deltex, UK). The procedure was converted to open laparotomy. Thereafter, we could find retroperitoneal hemorrhage, and vascular repair was done successfully. The patient recovered without any other complications.

Randomized controlled trial of intraoperative goal-directed fluid therapy in aerobically fit and unfit patients having major colorectal surgery

Intraoperative fluid therapy regimens using oesophageal Doppler monitoring (ODM) to optimize stroke volume (SV) (goal-directed fluid therapy, GDT) have been associated with a reduction in length of stay (LOS) and complication rates after major surgery. We hypothesized that intraoperative GDT would reduce the time to surgical readiness for discharge (RfD) of patients having major elective colorectal surgery but that this effect might be less marked in aerobically fit patients. In this double-blinded controlled trial, 179 patients undergoing major open or laparoscopic colorectal surgery were characterized as aerobically 'fit' (n=123) or 'unfit' (n=56) on the basis of their performance during a cardiopulmonary exercise test. Within these fitness strata, patients were randomized to receive a standard fluid regimen with or without ODM-guided intraoperative GDT. GDT patients received an average of 1360 ml of additional intraoperative colloid. The mean cardiac index and SV at skin closure were significantly higher in the GDT group than in controls. Times to RfD and LOS were longer in GDT than control patients but did not reach statistical significance (median 6.8 vs 4.9 days, P=0.09, and median 8.8 vs 6.7 days, P=0.09, respectively). Fit GDT patients had an increased RfD (median 7.0 vs 4.7 days; P=0.01) and LOS (median 8.8 vs 6.0 days; P=0.01) compared with controls. Intraoperative SV optimization conferred no additional benefit over standard fluid therapy. In an aerobically fit subgroup of patients, GDT was associated with detrimental effects on the primary outcome. UK NIHR CRN 7285, ISRCTN 14680495. http://public.ukcrn.org.uk/Search/StudyDetail.aspx?StudyID=7285.

Capability of a new paediatric oesophageal Doppler monitor to detect changes in cardiac output during testing of external pacemakers after cardiac surgery

The Cardio QP™ oesophageal Doppler monitor measures the velocity time integral of the blood flow in the descending aorta. Based on system integrated normograms of the aortic cross-sectional area of a paediatric population, the cardiac output is calculated and displayed. Evaluation of the capability of the Cardio QP™ to detect changes in cardiac output during desynchronizing ventricular pacing (VVI) in children after cardiac surgery. Eleven children (6 female, 5 male) with epicardial pacemaker electrodes admitted to the paediatric intensive care unit (PICU) after corrective surgery for congenital heart defects. Mean age: 6.3 (2.1-15.0) months, mean body weight: 5.3 (3.5-7.8) kg. After baseline measurements of cardiac output (base I), we performed 3 steps, each lasting 5 min: (1) ventricular pacing (VVI), (2) baseline (base II) recording, (3) atrial pacing (AOO). We measured the effects on haemodynamic parameters and blood gases as well as on the measured cardiac output. Ventricular pacing, with atrio-ventricular dyssynchrony, led to a significant drop in blood pressure and central venous saturation. Cardiac output parameters showed a decrease in stroke volume (SV) from 4.9±2.2 to 4.2±2.1 ml (P = 0.005) and cardiac index (CI) (2.6±1.1-2.1±0.8 ml/min/m(2)) (P = 0.009) during ventricular pacing. Cardiac index and haemodynamic parameters during atrial stimulation did not show significant changes from baseline. The Cardio QP™ seems to be capable of detecting slight changes in cardiac output.

NICE guidance on CardioQTM oesophageal Doppler monitoring

NICE guidance on CardioQTM oesophageal Doppler monitoring

A Comparison of Three Minimally Invasive Cardiac Output Devices with Thermodilution in Elective Cardiac Surgery

This study compared the cardiac output responses to haemodynamic interventions as measured by three minimally invasive monitors (Oesophageal Doppler Monitor the VigileoFlotrac and the LiDCOrapid) to the responses measured concurrently using thermodilution, in cardiac surgical patients. The study also assessed the precision and bias of these monitors in relation to thermodilution measurements. After a fluid bolus of at least 250 ml, the measured change in cardiac output was different among the devices, showing an increase with thermodilution in 82% of measurements, Oesophageal Doppler Monitor 68%, VigileoFlotrac 57% and LiDCOrapid 41%. When comparing the test devices to thermodilution, the kappa statistic showed at best only fair agreement, Oesophageal Doppler Monitor 0.34, LiDCOrapid 0.28 and VigileoFlotrac -0.03. After vasopressor administration, there was also significant variation in the change in cardiac output measured by the devices. Using Bland-Altman analysis, the precision of the devices in comparison to thermodilution showed minimal bias, but wide limits of agreement with percentage errors of Oesophageal Doppler Monitor 64.5%, VigileoFlotrac 47.6% and LiDCOrapid 54.2%. These findings indicate that these three devices differ in their responses, do not always provide the same information as thermodilution and should not be used interchangeably to track cardiac output changes.

The use of LiDCO based fluid management in patients undergoing hip fracture surgery under spinal anaesthesia: neck of femur optimisation therapy - targeted stroke volume (NOTTS): study protocol for a randomized controlled trial.

BackgroundApproximately 70,000 patients/year undergo surgery for repair of a fractured hip in the United Kingdom. This is associated with 30-day mortality of 9% and survivors have a considerable length of acute hospital stay postoperatively (median 26 days). Use of oesophageal Doppler monitoring to guide intra-operative fluid administration in hip fracture repair has previously been associated with a reduction in hospital stay of 4-5 days. Most hip fracture surgery is now performed under spinal anaesthesia. Oesophageal Doppler monitoring may be unreliable in the presence of spinal anaesthesia and most patients would not tolerate the probes. An alternative method of guiding fluid administration (minimally-invasive arterial pulse contour analysis) has been shown to reduce length of stay in high-risk surgical patients but has never been studied in hip fracture surgery.MethodsSingle-centre randomised controlled parallel group trial. Randomisation by website using computer generated concealed tables. Setting: University hospital in UK. Participants: 128 patients with acute primary hip fracture listed for operative repair under spinal anaesthesia and aged > 65 years. Intervention: Stroke volume guided intra-operative fluid management. Continuous measurement of SV recorded by a calibrated cardiac output monitor (LiDCOplus). Maintenance fluid and 250 ml colloid boluses given to achieve sustained 10% increases in stroke volume. Control group: fluid administration at the responsible (blinded) anaesthetist's discretion. The intervention terminates at the end of the surgical procedure and post-operative fluid management is at the responsible anaesthetist's discretion. Primary outcome: length of acute hospital stay is determined by a blinded team of clinicians. Secondary outcomes include number of complications and total cost of care.Funding NIHR/RfPB: PB-PG-0407-13073.Trial registration numberTrial registration: Current Controlled Trials ISRCTN88284896.

Enhanced recovery programmes; coming to a hospital near you!

Enhanced recovery programmes; coming to a hospital near you!

What is the optimal type of fluid to be used for peri‐operative fluid optimisation directed by oesophageal Doppler monitoring?

The objective of this review was to determine the optimal type or class of intravenous fluid to be used during peri-operative patient optimisation guided by oesophageal Doppler monitoring and to identify future directions for research. We undertook a literature review of patients undergoing major (general, colorectal, orthopaedic and urological) surgery, whose fluid therapy was managed using peri-operative oesophageal Doppler monitoring. We identified 10 studies that included 891 randomised patients. A variety of regimens and types of fluid were used in association with oesophageal Doppler monitoring, including crystalloid, gelatin and hydroxyethyl starch. A wide variety of hydroxyethyl starch preparations were used, including high molecular weight and highly substituted hetastarches, and lower molecular weight tetrastarches. Most studies were of high quality, associated with reduced hospital stay, but underpowered to evaluate other outcomes. In units with established enhanced recovery facilities, the benefits of colloid based on oesophageal Doppler monitoring were not reproduced. There is little evidence to support preferential use of any particular type of fluid during oesophageal Doppler guided optimisation; however, routine use of colloids is associated with significantly higher costs and may increase hospital stay. Furthermore, many of these fluids have not been evaluated in patient populations in whom optimisation is being applied or proposed, and the potential for harm cannot be excluded. Recommendations for future studies are provided, including adequate power for primary end points beyond hospital stay and adequate follow-up, and inclusion of a crystalloid comparison group.

Esophageal Doppler Monitoring during Colorectal Resection Offers Cost-Effective Improvement of Hemodynamic Control

ObjectivesHemodynamic control can improve the outcome of surgery. Esophageal Doppler monitoring measures blood flow by ultrasound waves. This work investigates the cost-effectiveness of this procedure during colorectal resection. MethodsMeta-analyses of randomized controlled trials of esophageal Doppler monitoring used in colorectal resection were conducted to help determine its cost-effectiveness. An analytical decision model was used to compare the cost-effectiveness of strategies involving conventional clinical assessment with or without the measurement of central venous pressure, with or without esophageal Doppler monitoring. Avoided mortality and avoided major complications were used as measures of clinical effectiveness. ResultsIn the meta-analyses comparing conventional clinical assessment plus central venous pressure monitoring with or without esophageal Doppler monitoring, statistically significant differences in total and major complications favoring the use of Doppler were found. No differences were seen in mortality. The use of esophageal Doppler monitoring was associated with lower costs, mainly due to fewer complications, shorter hospital stays and shorter surgery times. ConclusionsAlthough the information regarding the clinical effectiveness of esophageal Doppler monitoring in colorectal resection is limited, strategies including this form of blood flow monitoring may be cost-effective. Further comparisons of Doppler monitoring against other hemodynamic monitoring systems should be undertaken.

Oesophageal Doppler monitoring: should it be routine for high-risk surgical patients?

To determine whether sufficient evidence exists to justify routine use of oesophageal Doppler monitoring to guide perioperative haemodynamic management in high-risk surgery. Systematic reviews of the literature have been performed independently by the National Health Service Centre for Evidence-based Purchasing in the UK, and the US Agency for Healthcare-Related Quality. A before-after evaluation was also recently performed in three hospitals by the National Health Service Technology Adoption Centre. Although multicentre prospective randomized controlled trials are lacking, the evidence base for both outcome-benefit and cost-benefit is considered strong enough by the National Institute for Health and Clinical Excellence in the UK for them to recommend use of this technology in high-risk surgical patients. Whether these findings also apply to other monitoring technologies requires formal validation. Better patient outcomes can be achieved by perioperative haemodynamic optimization using oesophageal Doppler monitoring and should be considered for routine use in most types of high-risk surgery.

Dynamic and Static Parameters of Fluid Responsiveness, Volume 48, Number 1.

Dynamic and Static Parameters of Fluid Responsiveness, Volume 48, Number 1. Edited by Balachundhar Subramanian, M.B.B.S., M.D., M.P.H., and Kyung W. Park, M.D. Philadelphia, International Anesthesiology Clinics-Lippincott Williams and Wilkins, Winter 2010. Pages: 128. Price: $162.00.Fluid management in perioperative and critically ill patients remains a highly debated topic. There is a wide variety of practice, even within institutions, and, if you think of fluid as a drug, it is unique in that even the most junior member of the team can double or triple the dose without fear of comment by other members of the team. In recent years, there has been a renewed interest in the assessment of fluid responsiveness in critically ill patients to identify those patients for whom fluid therapy will be of benefit and, equally importantly, those for whom it will not. This interest has been driven by the emergence of a number of exciting new technologies. Dynamic and Static Parameters of Fluid Responsiveness reviews these technologies and increases the reader's understanding of the important concept of dynamic fluid responsiveness.The book is well organized into eight original articles. The first article illustrates the limitations of traditional static parameters of fluid responsiveness, such as central venous pressure, and outlines the physiologic concepts related to fluid loading. This leads to the next article that discusses the physiology behind dynamic fluid responsiveness and outlines the different technologies available to illustrate and use this approach in routine clinical practice. In many ways, these first two articles are the key to the book, providing the background information necessary to understand the subject. They are very well written and easy to understand, yet provide sufficient information to be recommended reading for both novice and expert.The next five articles look, in turn, at the different technologies available to monitor fluid responsiveness. The discussion of each device includes technical considerations behind how the device works as well as a detailed review of the evidence base for the technology. The text is necessarily detailed at times because the authors seek to provide the reader with a thorough understanding of the different systems available. The article on echocardiography was a useful inclusion and suitably brief because this technology is not widely used to predict fluid responsiveness, although it may have more of a role in the future as its use expands into noncardiac surgery. We particularly recommend the article on the FloTrac System (Edwards Life Science, Irvine, CA), which expertly reviews the device, particularly in relation to the different versions available, because the company has sought to improve its performance. The PiCCO (Pulsion Medical System AG, Munich, Germany) Monitor is also very well reviewed, although this technology is not yet widely available in the United States.We would have liked to see more information about the LiDCO system (Covidien, Mansfield, MA), particularly with respect to the newer LiDCO rapid device that was only briefly mentioned, despite its widespread use. There was also insufficient discussion of the use of stroke volume variation, as opposed to accurate cardiac output measurement with this system. The use of a noncalibrated device to trend cardiac output and optimize fluid status perioperatively during major surgery is, in our opinion, quite different compared with needing more precise cardiac output values in a critically ill patient. We also believe the editors could have included a separate article to review the esophageal Doppler monitor. As mentioned in the final article, the esophageal Doppler monitor has more outcome data for perioperative goal-directed fluid management than any other monitor. It can also be used to assess the corrected flow time, or duration of flow during systole, as a measure of preload.Using plethysmography to assess dynamic preload responsiveness is an emerging area and is expertly covered, with respect to both the possibilities and the limitations of these new devices. Finally, the last article summarizes the outcome data from randomized controlled trials involving restrictive or goal-directed fluid strategies. It is noteworthy that the limitations of nomenclature and fixed-volume amounts in the restrictive literature, as well as the confusion surrounding the third space, are well reviewed.Overall, the book offers a good and thorough review of the subject, with the caveats mentioned above. We are delighted to see an increasing interest and more publications devoted to this important subject, with the hope that the increasing body of evidence behind dynamic fluid responsiveness can be translated into a widespread change in practice. We would recommend this book to anyone with an interest in this important subject, and it would be a useful addition to any anesthesia or critical care departmental library.*Duke University Medical Center, Durham, North Carolina. tjgan@duke.edu

648 Oesophageal Doppler Monitor Detects Changes in Cardiac Index During Pacemaker Testing in Children After Cardiac Surgery

Background: The Cardio QP™ Oesophageal Doppler Monitor measures the velocity time integral of the blood flow in the descending aorta Based on nomogramms of the aortic cross sectional area of a paediatric population cardiac index is calculated and displayed on the monitor. Objective: Evaluation of the capability of the Oesophageal Doppler Monitor to detect slight changes in cardiac output as they occur during desynchronizing ventricular pacing (VVI) in children after cardiac surgery. Patients: 11 infants (6 female, 5 male) after corrective cardiac surgery of congenital heart defects Median age: 49 months (20-15 months), median weight: 44 kg (34- 78 kg). Interventions: After baseline measurements of cardiac output, we performed 3 steps of each 5 minutes: 1 ventricular- pacing, 2 baseline II, 3 atrial pacing in order to exclude effects of higher cardiac frequency We measured the effects on hemodynamic and respiratory parameters as well as on cardiac output. Measurements and Main Results: VVI pacing leads to a significant decrease in arterial blood pressure and central venous saturation Cardiac output parameters measured by the oesophageal Doppler monitor showed a significant decrease in stroke volume (SV) from 49 ± 22 to 42 ± 21 (p= 0005) and cardiac Index (CI) (26 ± 11 to 21 ± 08) (p= 0009) from baseline during ventricular stimulation The changes in Cardiac output and hemodynamic parameters during atrial stimulation did not show a significant difference from baseline. Conclusion: The oesophageal Doppler monitor may be reliable in the detection of slight changes in cardiac output.