[The effect of 6% (40/0.5) hydroxyethyl starch and Ringer's lactate on blood coagulation, laboratory parameters and circulation during peridural anesthesia].

We investigated the effects of 6% hydroxyethyl starch (HES 40/0.5) and lactated Ringer solution (LRS) on blood coagulation tests and laboratory parameters during epidural anesthesia. Additionally, the efficacy of this prophylactic intravenous fluid supply in preventing sympathetic blockade induced hypotension was studied. METHODS. A single shot lumbar epidural block was given to 55 patients using 14-18 ml of bupivacaine 0.75%. The patients were randomized to receive either 1000 ml 6% HES 40/0.5 or 1000 ml LRS starting 5 min before the epidural blockade was set. The first 500 ml was infused during a 15-min period and the remaining 500 ml solution during the next 30 min. Cardiovascular parameters were recorded and blood samples were taken 30, 60, 120 and 240 min after the start of the infusion. RESULTS. No significant differences were found in the cardiovascular parameters, although in patients with a cranial spread of epidural blockade above T 10, patients who received LRS showed more episodes of severe hypotension. Serum osmolarity, potassium and sodium remained constant throughout the observation period. HES 40/0.5 caused a significantly greater hemodiluting effect than LRS, which was evident in more pronounced temporary decreases in serum protein concentration, hemoglobin concentration, hematocrit, fibrinogen and platelets. In coagulation parameters LRS caused no changes of PTT and Quick, whereas HES 40/0.5% led to a significant prolongation of PTT and a decrease in Quick. CONCLUSION. Fluid supply with either LRS or 6% HES 40/0.5 cannot prevent the epidural blockade induced hypotension entirely. In epidural anesthesia with spread of blockade above T 10, 6% HES 40/0.5 is superior to LRS in the prevention of severe hypotension. The temporary increase in plasma volume after infusion of 6% HES 40/0.5 results in a greater hemodilution with a concomitant decrease of blood viscosity and improved microcirculation flow. These might be of interest in prevention of thromboembolic complications. The specific effects of the two solutions were also determinable during epidural blockade.