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To the Editor:
We read with interest the recently published study by Bishop and colleagues entitled "Prospective, Randomized Trial of Survivor Values of Cardiac Index, Oxygen Delivery, and Oxygen Consumption as Resuscitation Endpoints in Severe Trauma" (J Trauma 38:780, 1995).
The results of the study supported the use of resuscitation endpoints in severe trauma. We believe that the impact of the study and possibly the design of future studies may be strengthened by clarification of a few issues by the authors. These issues consist of informed consent, randomization, and agreement between figures and tables.
We request more disclosure on the issue of patient-informed consent. Some institutions require patient consent before randomization and will not accept delayed consent or a surrogate consent. Knowing the method of consent in this study may be useful to support change to a less restrictive consent policy at some institutions.
The control and protocol samples differed in size by a ratio of 1.3 to 1. Presumably this resulted from the method of randomization described in the methods as "...depending on the day of admission." Was the randomization an even day/odd day design? Was the randomization linked to the schedule of specific surgical teams? The authors should respond with more explicit information about how the patients were randomized.
The method of randomization in the study by Bishop and colleagues may not be ideal for larger studies. If a larger study were undertaken with a 1.3 to 1 ratio, this would produce significantly unequal sample sizes (p < 0.05) with less than a fourfold increase in patients randomized.
Finally, the data for cardiac index, oxygen delivery, and oxygen consumption at 72-120 hours in Table 6 do not correspond to the graphic data in Figure 1 Figure 2 Figure 3, respectively, at 72 to 120 hours for these variables. Figure 2 and Figure 3 show much greater separation between groups at 72-120 hours than the data in Table 6 suggest. Clarification of these data would be helpful.
We thank you for consideration of these issues.
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