Paper reports overview: Restrictive transfusions, experienced radiologists and prone positioning

This commentary reflects on the paper reports published in the Critical Care Forum between 10 July 2001 and 10 September 2001

The volume of published research in critical care continues to increase with each passing month. In this issue of Critical Care a few of the less well publicised but clinically important papers are reported on.

A continuing theme over recent months has been to reaffirm the potentially harmful effects of specific interventions. The Canadian Clinical Trials Group published the third paper from their investigations into the effects of a restrictive strategy of blood transfusion [1]. Their restrictive strategy sets the threshold for packed red cell transfusion at haemoglobin levels <8 g/dl, as opposed to their liberal strategy that sets the transfusion threshold at <10 g/dl. This latest study looks at the effects of the restrictive strategy on weaning from mechanical ventilation. Like the two previous studies from this group [2,3], the restrictive strategy is found to be at least as good as, if not significantly better than, the liberal transfusion strategy. On a similar theme, Putensen and colleagues [4] have published a trial that adds to the growing body of evidence that minimising sedation and maximising patient respiratory effort in patients with acute lung injury/adult respiratory distress syndrome (ARDS) is of significant benefit.

In the trauma literature, Davis and colleagues [5] report the results of a trial of imaging to exclude cervical spine injury. Their approach using dynamic fluoroscopy appears both thoughtful and sensible but perhaps most importantly they stress the need for, and value of, an experienced radiological opinion in the management of these patients.

From a French group comes a paper that demonstrates the vital importance of study design [6]. In their paper, the group eloquently show that a detailed understanding of the distribution of disease outcome is necessary to adequately power an outcome study and dictate the specific group to be targeted to answer a study hypothesis. They rightly stress that not adopting this approach is not only a waste of precious resources but also unethical. This issue is pertinent to the recently published and keenly anticipated Italian trial of prone positioning in ARDS patients [7]. When presenting the results of this trial prior to their publication, Gattinoni emphasised that, with hindsight, the design of this trial was flawed, thus the negative result fails to answer the question of whether or not to employ this intervention in ARDS patients [8]. Considerable basic research into prone positioning continues to be published with at least 5 papers published in the last 3 months. The optimal use of this strategy, in particular the duration of prone positioning, must be established before a further randomised control trial of this intervention is attempted.

In addition to these studies a number of other papers are worthy of general attention [9,10,11,12,13].