Do fluid administration and reduction in norepinephrine dose improve global and splanchnic haemodynamics?

We studied global and splanchnic haemodynamics in patients with septic shoc k, while reducing norepinephrine doses by progressive fluid loading adminis tration. Ten patients (six female, four male, aged 39-86 yr, mean 61 yr) we re assessed using a transpulmonary thermo-dye dilution technique to measure cardiac output, intrathoracic blood volume and total blood volume. Splanch nic blood flow was measured by the steady state indocyanine green technique using a hepatic venous catheter. Gastric mucosal blood flow was estimated by regional carbon dioxide tension (PRCO2). Hydroxyethylstarch was infused in two stages while maintaining mean arterial pressure, allowing a reductio n in norepinephrine dose from 0.54 to 0.33 to 0.21 mu g kg(-1) min(-1). Mea n (SD) heart rate significantly decreased, from 104 (13) to 94 (15) beats m in(-1). Total blood volume index (mean (SD)) increased from 2650 (638) to 3 655 (885) ml m(-2), intrathoracic blood volume index from 888 (204) to 1050 (248) ml m(-2) and cardiac index from 3.6 (1.0) to 4.0 (0.9) litres min(-1 ) m(-2). Splanchnic blood flow did not change significantly-either absolute (from 0.81 to 0.98 litres min(-1) m(-2)) or fractional (from 22.3% to 23.9 %). Gastric mucosal (PRCO2) increased from 7.5 (2.5) to 9.0 (2.8) kPa. The P-CO2 gap, i.e. the difference between regional and end-tidal PCO2, increas ed from 3.1 (2.5) to 4.0 (2.9) kPa. Marked individual variation in response s suggests that norepinephrine dose reduction by fluid loading in patients with stabilized septic shock does not necessarily increase global or splanc hnic blood flow.