Colloids versus crystalloids and tissue oxygen tension in patients undergoing major abdominal surgery

The effects of intravascular volume replacement regimens on tissue oxygen tension (ptio(2)) are not definitely known. Forty-two consecutive patients scheduled for elective major abdominal surgery were prospectively randomized to receive either 6% hydroxyethyl starch (HES) (mean molecular weight 130 kd, degree of substitution 0.4, n = 21) or lactated Ringer's solution (RL, n = 21) for intravascular volume replacement. Fluids were administered perioperatively and continued for 24 h on the intensive care unit to keep central venous pressure between 8 and 12 mm Hg. The ptio(2) was measured continuously in the left deltoid muscle by using microsensoric implantable partial pressure of oxygen catheters after the induction of anesthesia (baseline, T0), 60 min (T1) and 120 min thereafter (T2), at the end of surgery (T3), and on the morning of the first postoperative day on the intensive care unit (T4). HES 130/0.4 2920 +/- 360 mL and 11,740 +/- 2,630 mL of RL were given to the patients within the study period. Systemic hemodynamics and oxygenation (Pao(2), Paco(2)) did not differ significantly between the two volume groups throughout the study. From similar baseline values, ptio(2) increased significantly in the HES-treated patients (a maximum of 59% at T4), whereas it decreased in the RL group (a maximum of -23% at T4, P < 0.05). The largest differences of ptio(2) were measured on the morning of the first postoperative day. We conclude that intravascular volume replacement with 6% HES 130/0.4 improved tissue oxygenation during and after major surgical procedures compared with a crystalloid-based volume replacement strategy. Improved microperfusion and less endothelial swelling may be responsible for the increase in ptio(2) in the HES 130/0.4-treated patients.