Australasian Anaesthesia 2011 - Australian and New Zealand ...

184 Australasian Anaesthesia 2011Cardiac output monitoring in non-cardiac surgery: how and why? 185However, there are still reasons to question these conclusions. All the randomised controlled trials (RCTs) usingA more intensive algorithm targeting blood flow, or cardiac index (CI) first, and blood pressure second, is as shownminimally invasive monitors included in these meta-analyses have been small single centre studies, few with greaterin Figure 6.than 100 – 200 patients. Trials of this size are typically “efficacy studies” which can reflect the intense interest of acentre or research group in an intervention, but may not reflect the results of that intervention in more widespreadFigure 6. An intensive goal directed haemodynamic strategy targeting cardiac index first, andpractice. Research funded by commercial interests or negative studies in a field of research can encounter publicationincorporating the possibility of using an inotrope/chronotrope (such as dobutamine for example),bias and this can affect the results of meta-analyses. 37 There are a number of salient examples in the anaestheticwhere preload appears adequate but cardiac index remains low, implying cardiac dysfunction.and medical literature of failure of a meta-analysis of small RCTs to be confirmed by a subsequent large RCTconducted across a large number of centres. 38,39 There is a need for a large multicentre RCT of goal directed fluidand haemodynamic management in major surgery, to confirm the findings of research to date in this field. Theincreasing availability of minimally invasive monitors in clinical practice should make this feasible in the near future.A higher standard of evidence for the benefits goal directed management will assist in the wider adoption of theseCI < 2.5 L/min.m 2 ?devices.The slow penetration of these technologies into routine clinical practice up till now has been limited by otherYesSVV > 13% ?FTc < 350 msec?SV |^> 10%?Nofactors as well. These include lack of familiarity of the clinician and cost considerations, particularly of single-usedisposable components. These devices add to the complexity of the conduct of anaesthesia and may be perceivedas a distraction to the anaesthetist. Most of the available devices are marketed as stand-alone systems, and lackof integration with the rest of the patient monitoring system, contribute to this perception.Better integration into anaesthesia delivery and monitoring platforms will improve this. For example, integrationwith invasive or non-invasive blood pressure measurement allows automatic calculation of haemodynamic indicessuch as SVR which gives further data to guide fluid and vasopressor therapy. Indices of oxygen delivery areautomatically available when oximetry data is incorporated. Full integration allows optimal data display and alarmYesNoSVI