Polymyxin B hemoadsorption in endotoxic septic shock: ten questions on the Tigris trial

The Tigris trial recently reported that polymyxin B hemoadsorption (PMX) achieved a high posterior probability of benefit for mortality in adults with endotoxic septic shock (endotoxemia with multiple organ failure). The trial used a Bayesian framework with a prior derived from a subgroup of an earlier trial (EUPHRATES) and this subgroup was used to design eligibility criteria for Tigris. Ten questions that expose the trial's strengths and limitations are answered in this review. Writing as the trial investigators, our intention is to make the reasoning behind these decisions explicit, so that clinicians and trialists can judge what Tigris does, and does not, demonstrate.