Effect of dopexamine on CO₂ -gradients and splanchnic energy balance in septic shock

Objective

Septic shock is characterized by enhanced hepato-splanchnic blood flow resulting from increased metabolic activity. This hypermetabolism may lead to mismatch of regional O₂ supply and demand reflected by increased CO₂-gradients and lactate/pyruvate ratios. In patients after cardiac surgery dopexamine is known to increase splanchnic perfusion. Therefore, we studied the effect of dopexamine on regional CO₂-gradients and energy balance in patients with septic shock.

Patients and methods

Twelve patients with septic shock were studied. Cardiac index (CI) was ≥ 3 l/min/m² and noradrenaline ≥ 0.04 μg/kg×min^-1 was infused to maintain mean arterial pressure (MAP) ≥ 60 mmHg. In addition to routine systemic hemodynamics and gas exchange we inserted a Swan Ganz catheter into a hepatic vein to measure splanchnic blood flow (Qspl) using primed continous infusion of indocyanine green (ICG) dye. Moreover, we assessed splanchnic lactate uptake (Fick principle), hepatic venous lactate/pyruvate ratio as well as PCO₂ (PCO₂hv), splanchnic O₂ delivery (DO₂spl) and consumption (VO₂spl). The gatric mucosal PCO₂ (PCO₂gm) was determined via a nasogastric tube. Measurements were done before, during and after dopexamine infusion. Data were obtained after 90 min of hemodynamic steady-state. Dopexamine was titrated (1–4 μg/kg×min^-1) to obtain a 30% increase in CI.

Results

See Table.

Conclusion

The unpredictable changes in the metabolic state and regional PCO₂ gradients after a dopexamine-induced increase in DO₂spl, underscores the independent response of hepato-splanchnic perfusion and metabolism to therapeutic interventions.

Table