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Perioperative goal-directed therapy with uncalibrated pulse contour methods: impact on fluid management and postoperative outcome

2017; Elsevier BV; Volume: 119; Issue: 3 Linguagem: Inglês

10.1093/bja/aex282

1471-6771

Azriel Perel,

Non-Invasive Vital Sign Monitoring

Editor—The conclusions of the very recent meta-analysis by Michard and colleagues1Michard F Giglio MT Brienza N Perioperative goal-directed therapy with uncalibrated pulse contour methods: impact on fluid management and postoperative outcome.Br J Anaesth. 2017; 119: 22-30Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar in the British Journal of Anaesthesia is that the use of perioperative goal-directed therapy (GDT) with uncalibrated pulse contour (uPC) techniques is associated with a decrease in postoperative morbidity, but not associated with an increase in total fluid administration. An accompanying editorial has analysed in detail some methodological issues related to this and other systematic reviews, but has not challenged its conclusions.2Vistisen ST Keus E Scheeren TWL Methodology in systematic reviews of goal-directed therapy: improving but not perfect.Br J Anaesth. 2017; 119: 18-21Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar In fact, the editorial expanded these conclusions claiming that this systematic review provides us with the best currently available evidence on this topic. Although these conclusions seem logical, and may even be true, a more careful examination of this meta-analysis leads me to believe that its conclusions should be very different. Following a rigorous search strategy, the authors decided to include in the final analysis 19 studies, published between 2008 and 2015, in which the intervention included GDT with uPC methods.1Michard F Giglio MT Brienza N Perioperative goal-directed therapy with uncalibrated pulse contour methods: impact on fluid management and postoperative outcome.Br J Anaesth. 2017; 119: 22-30Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar Sixteen of these 19 studies were done using the FloTrac as the uPC method of choice, and only three used other uPC devices (LiDCOr – 2, and ProAQT -1). Of more interest, however, are the haemodynamic goals that were used in the GDT protocols of these studies. In 16 of the 19 studies, the main haemodynamic goal of the GDT protocol was a continuous dynamic parameter, namely the stroke volume variation (SVV) in 15 studies and the pulse pressure variation (PPV) in one. In nine of these studies other parameters such as the cardiac index (CI) were used as additional secondary goals. However, a fixed minimal value of CI was used as a goal in only one study, while stroke volume (SV) maximization corresponding to the plateau of the Frank–Starling relationship was used in only two studies. The first conclusion from this closer inspection of the meta-analysis, is that, as aptly said before, “GDT can be a vague term, meaning different things to different people and, depending on the clinical environment, sometimes even different things to the same person”.3Roche AM Miller TE Goal-directed or goal-misdirected—how should we interpret the literature?.Crit Care. 2010; 14: 129Crossref PubMed Scopus (11) Google Scholar For many years, recommended GDT protocols were based mainly on the augmentation of SV or CI to a maximal level with fluids alone, with or without further augmentation of oxygen delivery (DO2) by the addition of inotropes.4Hamilton MA Cecconi M Rhodes A A systematic review and meta-analysis on the use of preemptive hemodynamic intervention to improve postoperative outcomes in moderate and high-risk surgical patients.Anesth Analg. 2011; 112: 1392-1402Crossref PubMed Scopus (624) Google Scholar This haemodynamic strategy led in most cases to the administration of more, if not excessive, fluids to the GDT group, as Michard and colleagues agree (“at least in theory”).1Michard F Giglio MT Brienza N Perioperative goal-directed therapy with uncalibrated pulse contour methods: impact on fluid management and postoperative outcome.Br J Anaesth. 2017; 119: 22-30Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar This has been the background for the repeated recommendations that dynamic parameters (e.g. SVV, PPV) be used to guide fluid therapy, when appropriate.5Perel A Habicher M Sander M Bench-to-bedside review: functional hemodynamics during surgery - should it be used for all high-risk cases?.Crit Care. 2013; 17: 203Crossref PubMed Scopus (33) Google Scholar One of the main values of these parameters is that they can identify “non-responders” and hence may prevent unnecessary fluid challenges.5Perel A Habicher M Sander M Bench-to-bedside review: functional hemodynamics during surgery - should it be used for all high-risk cases?.Crit Care. 2013; 17: 203Crossref PubMed Scopus (33) Google Scholar 6Perel A Pizov R Cotev S Respiratory variations in the arterial pressure during mechanical ventilation reflect volume status and fluid responsiveness.Intensive Care Med. 2014; 40: 798-807Crossref PubMed Scopus (34) Google Scholar On the other hand, protocols that aim at SV maximization may end up with more than 70% of negative fluid challenges,7MacDonald N Ahmad T Mohr O et al.Dynamic preload markers to predict fluid responsiveness during and after major gastrointestinal surgery: an observational substudy of the OPTIMISE trial.Br J Anaesth. 2015; 114: 598-604Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar as seems to be the case in the OPTIMIZE trial.8Pearse RM Harrison DA MacDonald N et al.Effect of a perioperative, cardiac output-guided hemodynamic therapy algorithm on outcomes following major gastrointestinal surgery: a randomized clinical trial and systematic review.JAMA. 2014; 311: 2181-2190Crossref PubMed Scopus (4) Google Scholar Thus it is no wonder that the meta-analysis by Michard and colleagues, which includes mainly studies where dynamic parameters had been used as haemodynamic goals, shows that GDT is not associated with more fluid administration.1Michard F Giglio MT Brienza N Perioperative goal-directed therapy with uncalibrated pulse contour methods: impact on fluid management and postoperative outcome.Br J Anaesth. 2017; 119: 22-30Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar The message needs however to be better clarified. This meta-analysis is not about GDT. This meta-analysis is about dynamic parameters-based GDT. The second question that comes to mind is why was the intervention that was chosen for the literature search of this meta-analysis defined as “GDT with uPC methods”.1Michard F Giglio MT Brienza N Perioperative goal-directed therapy with uncalibrated pulse contour methods: impact on fluid management and postoperative outcome.Br J Anaesth. 2017; 119: 22-30Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar As said before, the actual measurement of cardiac output (CO) was used as a main determinant in only three of the 19 studies and had much lesser importance on the haemodynamic management compared with dynamic parameters. Hence the accuracy of the CO measured by this uPC device, a topic of obvious great interest, played little if any role in the results of this meta-analysis. In spite of this, the accompanying editorial claims that “although the accuracy of uPC devices has been questioned, this systematic review shows that they are clinically useful when used in combination with a GDT therapy protocol”.2Vistisen ST Keus E Scheeren TWL Methodology in systematic reviews of goal-directed therapy: improving but not perfect.Br J Anaesth. 2017; 119: 18-21Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar This conclusion is misleading as the CO accuracy of these devices did play a minimal role, if any, in the results of the meta-analysis. Similarly, the editorial's claim that this meta-analysis shows that SV and CO optimization do not lead to excessive fluid administration2Vistisen ST Keus E Scheeren TWL Methodology in systematic reviews of goal-directed therapy: improving but not perfect.Br J Anaesth. 2017; 119: 18-21Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar is questionable as only a minority of the included studies have used the SV or CO as a goal. Limiting this meta-analysis only to studies that have used uPC devices may have introduced other unwanted and potentially misleading elements. For example, the POM-O study,9Ackland GL Iqbal S Paredes LG et al.Individualised oxygen delivery targeted haemodynamic therapy in high-risk surgical patients: a multicentre, randomised, double-blind, controlled, mechanistic trial.Lancet Respir Med. 2015; 3: 33-41Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar a large randomized controlled trial published in the Lancet Respiratory Medicine in 2015, in which the intervention group received twice the amount of colloids in an attempt to achieve preoperative DO2 values, has not been included in this analysis. The most plausible reason for this omission is that the CO monitor used in this study was the LiDCOPlus, which cannot be considered as a uPC device as it uses lithium dilution for the measurement of CO. Similarly, other GDT studies using transpulmonary thermodilution with the PiCCO monitor10Goepfert MS Richter HP Zu Eulenburg C et al.Individually optimized hemodynamic therapy reduces complications and length of stay in the intensive care unit: a prospective, randomized controlled trial.Anesthesiology. 2013; 119: 824-836Crossref PubMed Scopus (127) Google Scholar 11Smetkin AA Kirov MY Kuzkov VV et al.Single transpulmonary thermodilution and continuous monitoring of central venous oxygen saturation during off-pump coronary surgery.Acta Anaesthesiol Scand. 2009; 53: 505-514Crossref PubMed Scopus (64) Google Scholar have not been included in the final analysis, and there may be of course a few more. Including only studies that have been using uPC devices may have introduced another confounder, namely the exclusion of all studies in which the plethysmographic variability index (PVI) was used as a dynamic indicator to guide fluid management. This exclusion seems unjustified, as “pleth variability index” is one of the search terms that were used in this meta-analysis, and, as already said, in most of the included studies dynamic parameters played a central role. The fact that the PVI is measured by a pulse oximeter and not by a uPC device does not seem like a good enough reason for such exclusion. There are at least three studies in which the use of the PVI in a GDT protocol has led to considerably less fluids being administered to the patients in intervention group compared with those in the control group.12Forget P Lois F de Kock M Goal-directed fluid management based on the pulse oximeter-derived pleth variability index reduces lactate levels and improves fluid management.Anesth Analg. 2010; 111: 910-914Crossref PubMed Scopus (178) Google Scholar, 13Yu Y Dong J Xu Z Shen H Zheng J Pleth variability index-directed fluid management in abdominal surgery under combined general and epidural anesthesia.J Clin Monit Comput. 2015; 29: 47-52Crossref PubMed Scopus (27) Google Scholar, 14Thiele RH Rea KM Turrentine FE et al.Standardization of care: impact of an enhanced recovery protocol on length of stay, complications, and direct costs after colorectal surgery.J Am Coll Surg. 2015; 220: 430-443Abstract Full Text Full Text PDF PubMed Scopus (276) Google Scholar In one of these, which included an Enhanced Recovery Protocol, PVI-based fluid management led to a mean decrease of more than two litres in the intraoperative net fluid balance.14Thiele RH Rea KM Turrentine FE et al.Standardization of care: impact of an enhanced recovery protocol on length of stay, complications, and direct costs after colorectal surgery.J Am Coll Surg. 2015; 220: 430-443Abstract Full Text Full Text PDF PubMed Scopus (276) Google Scholar The inclusion of these studies in this meta-analysis may have resulted in a stronger conclusion about the ability of GDT protocols that are based on dynamic parameters to reduce the amount of intraoperative fluids. It is important to note, however, that the use of dynamic parameters to guide fluid management, in and by itself, may result in more fluids being administered if the chosen threshold value is too low or within the grey zone.15Lai CW Starkie T Creanor S et al.Randomized controlled trial of stroke volume optimization during elective major abdominal surgery in patients stratified by aerobic fitness.Br J Anaesth. 2015; 115: 578-589Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar, 16Bickenbach J Marx G Some light in the grey zone?.Br J Anaesth. 2017; 119: 5-6Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar Finally yet importantly, Michard and colleagues assume that similar volumes of colloids and crystalloids are equivalent. But that is a different story. In summary, a more appropriate conclusion of this meta-analysis is that guiding fluid administration by dynamic parameters is associated with better outcome but is not associated with more fluid administration. Including other studies that have used dynamic parameters (such as the PVI) as a goal, and excluding the few studies which attempted to maximize SV using a uPC device from this meta-analysis, may have resulted in different, yet more robust conclusion, namely, that guiding fluid administration by dynamic parameters is associated with less fluids and with better outcome. The author serves as a consultant to Masimo Inc., Irvine, CA. USA, and to Pulsion/GETINGE, Munich, Germany.