In Response

Our recent analysis evaluated the effect of vasopressor infusions in patients having major spine surgery.1 From the perspective of renal safety of Hextend (6% hetastarch in lactated electrolyte; Hospira, Forest Lake, IL), it is a large but uncontrolled case series which constitutes weak evidence—although we agree that there was no signal for harm.2 Far stronger evidence is available, at least for newer hetastarch plasma expanders. We recently published a trial of >1000 patients who were randomized to goal-directed crystalloid versus goal-directed hetastarch (hydroxyethyl starch 6% 130/0.4; Voluven, Fresenius Kabi, Germany).3 The relative volume expansion with each type of fluid changes over time and probably varies among patients. Goal-directed fluid administration was, therefore, a key part of the protocol because it assured that the patients randomized to each fluid were given physiologically comparable amounts. Patients assigned to crystalloid received a median (quartile 1, quartile 3) amount of 3.2 l (2.3, 4.4) of crystalloid, and patients assigned to colloid received 1.0 L (0.5, 1.5) of colloid and 1.8 L (1.2, 2.4) of crystalloid. The estimated intention-to-treat common effect relative risk for the primary composite of major complications was 0.90 for colloids versus crystalloids (95% confidence interval [CI], 0.65–1.23; P = .51), and 18% (91 of 523) of colloid patients and 20% (103 of 534) of crystalloid patients incurred at least one component of the primary outcome composite. There was no evidence of renal toxicity either acutely or up to 6 months after surgery (Figure).Figure.: Boxplots of preoperative serum creatinine concentration and maximum postoperative serum creatinine before hospital discharge and within 6 mo in patients randomly assigned to intraoperative crystalloids or hetastarch. Postdischarge length of follow-up across patients is presented as means ± SDs. No differences were found. SD indicates standard deviation. Reprinted with permission from Kabon et al.3Although prolonged use of high-volume hetastarch appears to be harmful in critical care patients,4,5 available evidence indicates that 500–1500 mL of the solution is safe for routine perioperative use. Daniel Sessler, MDDepartment of Outcomes ResearchAnesthesiology InstituteCleveland ClinicCleveland, Ohio Maged Argalious, MD, MBA, MEd, FASE, FASADepartment of General AnesthesiologyAnesthesiology InstituteCleveland ClinicCleveland, Ohio Ehab Farag, MD, FRCA, FASADepartments of General Anesthesiology and Outcomes ResearchAnesthesiology InstituteCleveland ClinicCleveland, Ohio[email protected]