Isoproterenol infusion and microcirculation in septic shock

INTRODUCTION Our study primarily aimed at investigating the effect of isoproterenol infusion on tissue oxygen saturation in patients with septic shock. The secondary aim was to assess the relation between cardiac index, central venous oxygen saturation and tissue oxygen saturation. METHODS This retrospective study was conducted from December 2010 to March 2012. We included 14 consecutive patients with septic shock treated with isoproterenol. All patients were monitored by cardiac index and tissue oxygen saturation. From medical charts, routine hemodynamic data were extracted one hour before and six hours after the onset of isoproterenol infusion. RESULTS From baseline to H6, tissue oxygen saturation levels rise from 78 [72-82]% to 85 [78-88]% (p = 0.03). Isoproterenol infusion was associated with an increase of central venous oxygen saturation (from 67 [65-74]% to 84 [77-86]%, p = 0.02) and cardiac index (from 2.9 [2.7-3.1] L/min/m² to 3.9 [3.0-4.4] L/min/m², p = 0.006). Tissue oxygen saturation was correlated neither to cardiac index (p = 0.14, R(2) = 0.08) nor to central venous oxygen saturation (p = 0.19, R(2) = 0.10). CONCLUSIONS Use of isoproterenol was associated with an increase of tissue oxygen saturation. This increase was not correlated to cardiac index, suggesting a decoupling between macrocirculation and microcirculation.