Ghosh, Arthur and Klein are to be congratulated for their critical analysis of the evidence presented to the National Institute for Health and Clinical Excellence (NICE) about oesophageal Doppler monitoring (ODM) . I share their view that it may have been premature to recommend this particular monitor before its competitors. As NICE stated that “there is no evidence of adverse events which suggests that the use of the CardioQ-ODM is harmful to patients”, we must presume that the case report of haematemesis after ODM was not presented to them .
In my view, the NICE guidelines paid inadequate attention to the type and amount of fluids that are integral to the monitor’s performance, and that are a potential source of harm. Morris and Rogerson’s review  demonstrated that the potential for such harm is largely unexplored. Crystalloid boluses are intrinsically safer and much cheaper than currently used plasma substitutes, but to the best of my knowledge are not included in current trials. The standard view, that colloids are necessary for plasma volume expansion because crystalloids are poorly retained in the circulation of anaesthetised patients, is not supported by the evidence . Moreover, exposing large numbers of non-hypovolaemic and potentially atopic patients to modified fluid gelatins (and possibly other plasma substitutes) will increase the proportion of the population who are primed for a serious anaphylactoid response on their second exposure . In my view, patients should only be invited to consent to infusion of plasma substitutes as part of an ethically approved trial that includes a crystalloid control group and full disclosure of the known risks .