A randomized clinical trial of 10% pentastarch (low molecular weight hydroxyethyl starch) versus 5% albumin for plasma volume expansion after cardiac operations.

Pentastarch is a hydroxyethyl starch similar to hetastarch, but with a lower average molecular weight (264,000 versus 450,000) and fewer hydroxyethyl groups (molar substitution ratio = 0.45 versus 0.70). These characteristics result in enhanced enzymatic hydrolysis, faster renal elimination (initial intravascular half-life = 2.5 versus 25.5 hours), and less effect on coagulation. We report on a randomized clinical trial comparing the clinical efficacy and safety of 10% pentastarch (group P) for plasma volume expansion after cardiac operations with that of 5% serum albumin (group A). During the first 24 hours after arrival of the patient in the intensive care unit, colloid was infused to maintain a cardiac index of 2.0 L/m2 or more and a mean arterial pressure within 10% of the preinduction value. Group P (n = 50) received 1706 +/- 393 ml of colloid (mean +/- standard deviation) during this period, and group A (n = 44), 1794 +/- 341 ml (p = no significant difference). Hemodynamic responses to infusion were similar for both groups, although in group P a greater increase in both cardiac index (0.5 +/- 0.5 versus 0.3 +/- 0.5 L/min/m2 in group A, p less than 0.01) and left ventricular stroke work index (10.8 +/- 8.0 versus 5.8 +/- 6.0 gm-m/m2, p less than 0.01) was observed during infusion of the first 500 ml. There were no significant differences in any of the measured respiratory parameters (alveolar-arterial oxygen gradient, estimated shunt fraction, and effective pulmonary compliance). Hemodilution with colloid significantly reduced serum protein levels in group P by 24 hours postoperatively (4.0 +/- 0.6 versus 5.0 +/- 0.7 gm/dl in group A, p less than 0.05), although mean serum colloid osmotic pressure was similar (15.4 +/- 2.6 [P] versus 15.5 +/- 2.7 mmHg [A], p = no significant difference). There were no significant between-group differences in prothrombin time, activated partial thromboplastin time, platelet count, bleeding time, or coagulation factors (fibrinogen, V, VII, VIII, or IX) on postoperative days 1 and 7. Perioperative fluid balance, weight change, chest tube output, red blood, platelet, or fresh frozen plasma usage, reexploration for bleeding, and clinical outcome were also similar. These findings indicate that pentastarch is as safe and effective s 5% albumin for plasma volume expansion after cardiac operations with no apparent adverse effects on coagulation. If commercially available at a lower cost than albumin, it would appear to be a reasonable first choice for colloid therapy in this setting.