Prone to survive and the priority rule in science

Medical Science Monitor

Jacob Puliyel

Prone to survive and the priority rule in science
Jacob Puliyel
Corresponding Author: Jacob Puliyel, e-mail:
Source of support: None
In 2005 we published the first study to show that mortality can be reduced by prone ventilation [1]. This study
followed the large trial by the Prone-Supine Study Group of Gattinoni and colleagues published in the NEJM in
2001 [2] and another in 2005 that failed to show benefit [3].
We have speculated that the earlier trials failed to show benefit because the protocols of these studies stipulated
that physicians do not change ventilator settings during the period of prone ventilation (in order to standardize
the changes in gas exchange induced by this maneuver). As per protocol, both the prone and supine
groups were subjected to the same mean airway pressures (MAP) and tidal volumes even after it was noted
that the PaO2:FiO2 had improved in the prone group and they could be managed with lower MAP [4]. Gattinoni
responded to our criticism of his study and conceded that, in retrospect, our approach of reducing ventilation
as oxygenation improved was more appropriate [4].
Now a new study by the PROSEVA group has found that prone ventilation does indeed save lives. The stated
rationale for the new study by the PROSEVA Study Group of Guerin and colleagues, in severe acute respiratory
syndrome (ARDS) [5], was the meta-analysis data showing improved survival with prone position in patients
with severe hypoxemic ARDS. The authors overcame the drawback of the older studies by targeting the a tidal
volume of 6 ml per kilogram and the PEEP level selected from a PEEP-FiO2 table and they have demonstrated
a survival advantage for prone ventilation. However, analysis stratified according to quartile of PaO2:FiO2 ratio
at enrollment showed no significant differences in outcome in this study.
They assumed a priori that benefits will accrue only to those with severe ARDS and so they report that prone
ventilation helps this group, although their analysis shows severity of ARDS has little to do with improved survival.
The authors do not acknowledge our previous communications in the literature. We point to more than
a matter of priority in science, which is important in itself. Our findings suggest that prone ventilation may be
beneficial in reducing ventilator-induced lung injury in all ventilated patients and this needs to be investigated
in a wider context.
1. Sawhney A, Kumar N, Sreenivas V et al: Prone versus supine position in mechanically ventilated children:
a pilot study. Med Sci Monit, 2005; 11(5): CR235–40
2. Gattinoni L, Tognoni G, Pesenti A et al, Prone-Supine Study Group: Effect of prone positioning on the survival
of patients with acute respiratory failure. N Engl J Med, 2001; 345(8): 568–73
3. Gattinoni L, Vagginelli F, Carlesso E et al, Prone-Supine Study Group: Decrease in PaCO2 with prone position
is predictive of improved outcome in acute respiratory distress syndrome. Crit Care Med, 2003; 31(12):
4. Sawhney A, Puliyel JM: Prone to survive. Crit Care Med, 2005; 33(10): 2448; author reply 2448–49
5. Guérin C, Reignier J, Richard JC et al, PROSEVA Study Group: Prone positioning in severe acute respiratory
distress syndrome. N Engl J Med, 2013; 368(23): 2159–68
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