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The National Institute for Health and Clinical Excellence (NICE) has recently issued guidance [1] on the use of oesophageal Doppler monitoring during surgery. This guidance, which was published in March 2011, was the second ever published medical technologies guidance from NICE. This novel type of guidance was introduced in 2010 and is described as being designed to select and evaluate new or innovative technologies, including devices and diagnostics. The specific technologies that are investigated are recommended either by the newly formed Medical Technologies Advisory Committee or nominated by clinicians or by manufacturers themselves. The National Institute for Health and Clinical Excellence then commissions an independent academic centre to review and critique the evidence on the technology, and also asks the manufacturer to submit any supporting evidence, before publishing its guidance and distributing it to the National Health Service (NHS) in England.

The guidance, entitled CardioQ-ODM Oesophageal Doppler Monitor, recommends that: “The CardioQ-ODM [™ Deltex Medical, West Sussex, UK] should be considered for use in patients undergoing major or high-risk surgery or other surgical patients in whom a clinician would consider using invasive cardiovascular monitoring”, and: “There is a reduction in post-operative complications, use of central venous catheters and in-hospital stay (with no increase in the rate of re-admission or repeat surgery) compared with conventional clinical assessment with or without invasive cardiovascular monitoring. The cost saving per patient, when the CardioQ-ODM is used instead of a central venous catheter in the peri-operative period, is about £1100 based on a 7.5-day hospital stay.

It would be reasonable to expect that such a robust commendation of a single named device would be based on an equally robust body of evidence. In point of fact, NICE considered only eight quite small randomised clinical trials [2–9]. Three of these trials used the CardioQ itself [6–8], the rest used other iterations of the device. These single centre trials included a total of only 764 patients, about half of whom were controls. In addition, NICE gave some consideration to an audit [10] of a mixture of major surgical procedures that included 626 patients in whom the CardioQ was used. Two meta-analyses of data drawn principally from the same clinical trials were also taken into account [11, 12].

Of the eight clinical trials considered by NICE, three [2, 3, 6] were from the same centre (University College Hospital, London), which states on some of its later publications that it receives unrestricted grant funding from Deltex Medical, the manufacturers of the CardioQ. Conflict of interest statements were also available for four of the other five trial groups; three [5, 7, 9] were also in receipt of some funding from Deltex. It has yet to be established whether receipt of commercial funding from the makers of a device may in itself affect the outcome of studies relating to that device. No aspersions are being cast on the propriety of these studies, but commercial funding of studies does raise questions about their independence and the weight that should be given by such an influential body as NICE in interpreting their conclusions. This is particularly pertinent when there are few data from non-commercially associated studies to consider. Interestingly, a recent editorial [13] highlighted the influence of industry on regulatory decisions and whether editorials and reviews should be commissioned from experts with ties to industry.

The basis for NICE’s recommendation is the impressive reduction in length of hospital stay associated with use of the CardioQ. However, not all of the studies reviewed by NICE actually reported this outcome: Venn et al. (90 patients) described a reduction in the number of days to being declared medically fit for discharge, but hospital stay was not altered [4]; moreover, Senagore et al. (64 patients) reported an increased length of stay in those patients in whom goal directed fluid therapy was used [9]. In one of the studies that did report a reduction in hospital stay, this difference was small (100 patients, median stay reduced from 7 to 6 days, range and interquartile range not reported), and the authors stated that this difference could have been ascribable to factors other than goal directed fluid therapy [5].

The patient groups included in the literature reviewed by NICE were extremely heterogenous. McKendry et al. studied postoperative cardiac surgery patients in the intensive care unit [6], whilst Mythen et al. studied peri-operative cardiac surgery patients [2]. Two studies examined patients having surgery following hip fracture [3, 4]; three looked at patients having colorectal surgery [7–9]; and one studied a mixed group of patients who required gynaecological, urological and general surgical procedures [5]. Some may be concerned about the validity of drawing strong conclusions from such a varied collection of patients in small single-centre clinical trials, especially bearing in mind the difference in fluid management between elective cardiac surgery, urgent or emergency hip fracture surgery, and general surgical procedures, as well as inherent differences in intra and postoperative management.

Most people reading the NICE guidance summary would conclude that there is a recommendation to dispense with more invasive measures, such as central venous catheters, and to combine routine clinical assessment and monitoring with the CardioQ alone to achieve these remarkable results. A Health Technology Assessment report commissioned by the USA Department of Health in 2007 [14], which based its findings on seven randomised clinical trials [2–5, 7, 8, 15], came to the conclusion that the strength of evidence for a significant reduction in hospital stay was weak when comparing the combination of conventional clinical assessment plus oesophageal Doppler monitoring to conventional clinical assessment alone during surgery. Furthermore, the low number of studies precluded a quantitative estimate of the reduction in length of hospital stay for this particular comparison.

All of the trials considered by the American report except one [15] were the same as those forming the bulk of the clinical trial data on which NICE based its guidance. So what additional data did NICE consider that led to its issuing guidance giving the impression that use of the CardioQ should lead to a reduction in the use of central venous catheters for monitoring? In fact, NICE included two other studies [6, 9]. One [6] was conducted in postoperative cardiac surgical patients – again, hardly comparable to intra-operative general surgical or orthopoedic patients – and in the other [9], the investigators concluded that they could identify no clinically significant benefit in terms of length of stay with goal directed fluid management. The other data taken into consideration by NICE come from a prospective audit [10] of the intra-operative use of the CardioQ in 626 patients undergoing a variety of surgical procedures at three different hospitals in the UK. The data from these patients were then compared with matched, historical controls selected by case review of records of patients undergoing surgery in the previous year at each of the hospitals. The process by which the historical controls were selected appears to have been by hand-picking individual cases, and not by inclusion of a series of sequential cases at each site. Use of such a database may make definitive conclusions difficult to accept [16].

After the publication of each NICE guidance, the recommendations are disseminated to NHS hospital trusts in England. Each trust is then required to consider the recommendations and report back to NICE about their implementation, or to report the reasons for failure to do so. This puts pressure on managers and clinicians to adopt the recommendations. The NICE technology guidance does state in its introductory paragraph that “the specific recommendations on individual technologies are not intended to limit use of other technologies which may offer similar advantages”. However, it does not make clear in its recommendations that other technologies may be as effective, or even more effective, but have not been reviewed. By examining an individual device in isolation and reporting on the merits of that device alone, NICE may be unintentionally guilty of promoting the use of one manufacturer’s device over that of its competitors. We feel that a more balanced form of technological guidance may be appropriate, and only issued if sufficient data from competing technologies or independent sources are available. This would allow clinicians to examine the evidence in its wider context.

In relation to the CardioQ guidance we appear to be in danger of losing sight of the fact that it is the intervention based on the measurements from the monitoring device, and not the monitoring device itself, that alters outcome [17]. When reading the clinical trials relating to use of the CardioQ, it is striking that the prime intervention differentiating controls from study group patients is the infusion of about 500 ml colloid intra-operatively. Can it really be that a monitoring device used for up to four hours out of an eight-day hospital stay, and the infusion of a small bag of fluid, can save the NHS £1100 per patient? If so, why not just adopt a less conservative approach to intra-operative fluid balance and dispense with the monitoring device as well?

Competing interests

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  2. Competing interests
  3. References

No external funding and no competing interests declared

References

  1. Top of page
  2. Competing interests
  3. References
  • 1
    National Institute for Health and Clinical Excellence. Medical technologies guidance MTG3: CardioQ-ODM oesophageal doppler monitor. March 2011. http://www.nice.org.uk/MTG3 (accessed 03/10/2011).
  • 2
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