Commentary Septic shock resuscitation: what goals and how to achieve

The need to achieve adequate tissue oxygen delivery early in patients with septic shock is well established. However, it is less well recognized that tissue hypoperfusion can exist despite normalization of systemic hemodynamics. Efforts to resuscitate septic patients until adequate tissue perfusion has been achieved can potentially improve outcome. In a multicenter study, 130 patients with septic shock were resuscitated within 12 hours of diagnosis using a protocol including goals for mean arterial and pulmonary artery occluded pressures, urinary output, arterial pH, and hemoglobin goals. They were then randomly assigned to further resuscitation with either a cardiac index (≥3 l/minute per m 2 ) or a gastric mucosal pH (≥7.32) target. The intensive care unit length of stay and 28-day mortality did not differ between groups, but more patients in the cardiac index group were in the target range, both at baseline and after resuscitation, as compared with the gastric mucosal pH group. In contrast to cardiac index, gastric mucosal pH at baseline and at 24 and 48 hours predicted mortality. Whether other targets for the chosen variables, or different and - in particular - earlier resuscitation efforts would have favored one group cannot be concluded from the data provided. The previous issue of Critical Care includes a report of a multicenter study in which cardiac index and gastric mucosal pH targets were compared during resuscitation of patients with septic shock [1]. Similar to all other hemodynamic variables with the exception of central venous oxygen saturation, the value of a cardiac index target in the resuscitation of patients in septic shock has not been established. In contrast, achievement of other goals in the treatment of septic patients (for instance, early and adequate antibiotic treatment) has been associated with improved outcomes. Because ‘normal’ systemic hemodynamics do not necessarily guarantee adequate tissue oxygen supply, monitoring organ perfusion or function may be more relevant. It has been shown that persistent microcirculatory alterations are associated with organ failure and mortality in patients with septic shock [2]. Gastric mucosal pH (pHi) is an interesting parameter that has been shown to predict outcome in many patient groups [3,4]. However, pHi-guided resuscitation has not improved survival rates. pHi is a composite variable that reflects not just adequacy of local perfusion but also systemic metabolic acid-base homeostasis and ventilation. The interaction of the components of pHi and their response to treatment may confound the interpretation and prognostic relevance of gastric mucosal acidosis.