ABSTRACT
To understand why these differences existed and derive a recommended approach to ventilating ARDS patients from these data, careful comparison of actual data for VT, plateau pressure (P plat) and PEEP in each trial group (Figure 15.9) must be performed and compared with the actual protocols for each trial (Table 15.3). As noted in Table 15.3, by design large differences in VT and as a result Pplat between
groups should have occurred in each trial; however, actual data in Figure 15.9 would indicate that only in the Amato et al.11 and NIH (ARDSnet)12 trials were protocolized differences in VT and Pplat between groups maintained. In all three of
the other trials only small difference existed in VT and PPlat between control and LPVS groups. As a result, the VT difference signal may have been insufficient in the
Brochard et al.36, Stewart et al.35, and Brower et al.34 trials to produce an effect on outcome, whereas in the NIH 12 and Amato et al.11 trials much larger difference in VT and Pplat were maintained. In fact, in these trials over the first 7 days VT values
of 6 and 12 mL kg - 1 were maintained in the two groups. However, the question to be asked is why the NIH12 trial required about 425 patients in each group to demonstrate a significant difference in mortality between groups when the Amato et al.11 trial was able to demonstrate a difference in mortality with only 29 patients in the LPVS group and only 24 patients in the control group. The answer to this may be in the approach to setting PEEP.
