To the Editor:
Gómez-Izquierdo et al. report the results of a randomized, methodologically flawless clinical trial to analyze the influence of goal-directed hemodynamic therapy in the postoperative ileus within a well-established enhanced recovery protocol.1 This strategy eliminates all the confounding factors that could alter the results of a single intervention. Taking into account that fluid therapy in the control group was based on traditional principles, the conclusion about the goal-directed hemodynamic therapy obtained from this study should be generalizable. Nevertheless, there are certain aspects to consider:
There is scientific interest in removing the goal-directed hemodynamic therapy from the enhanced recovery protocols and questioning the value of its individual components, especially the value of the stroke volume optimization.2 However, intraoperative fluid management outside clinical trials is extremely variable,3 and both an excessively restrictive and an excessively liberal approach lead to an increase in postoperative ileus.4 Moreover, observational studies performed within enhanced recovery protocols repeatedly showed that inadequate fluid therapy was independently associated with postoperative complications.5,6 Although it has been suggested that goal-directed hemodynamic therapy, and especially the stroke volume optimization,2 lead to excessive fluid administration, the systematic review recently published by Michard et al. confirmed otherwise.7 The same outcome has been corroborated by a Gómez-Izquierdo et al. study, in which similar amounts of fluids were given on the day of surgery.1 The administration of vasopressors and inotropics were also similar in both groups. Interestingly, these drugs were administered to both groups without a clinical protocol. Additionally, although the goal-directed hemodynamic therapy group had higher cardiac output, stroke volume, and mean arterial pressure values throughout the surgery, these were not significantly higher compared with the control arm.1 Consequently, using an equivalent amount of fluids and vasopressors, both groups reached the same hemodynamic goals, which could explain the lack of efficacy of the goal-directed hemodynamic therapy in this trial, even with a significantly higher weight balance gain on the first day in the control group. As in previous trials,8 it would have been interesting to analyze which (risk) patients and which hemodynamic values were associated with postoperative complications.
Certain subsets of patients rather than all patients undergoing colorectal surgery with enhanced recovery protocols seem to benefit the most from goal-directed hemodynamic therapy. Meta-analysis demonstrated the futility of the goal-directed hemodynamic therapy in low-risk surgical patients.2,9 Gómez-Izquierdo et al. conducted their study in relatively healthy (mainly American Society of Anesthesiologists status II) and young patients, and the incidence of postoperative ileus was lower than expected. This subgroup of patients probably has a higher risk of volume overload than tissue hypoperfusion, so a balanced fluid therapy generally should be sufficient to achieve outcomes. Recently, Tengberg et al. showed a statistically significant reduction in postoperative mortality in acute high-risk abdominal surgery by implementing enhanced recovery protocols with goal-directed hemodynamic therapy, based mainly on stroke volume optimization with colloids (15 vs. 22%; P = 0.005).10 This is consistent with a previous meta-analysis that showed a reduction in complications only in high-risk patients (relative risk 0.57; 95% CI, 0.41 to 0.78; P = 0.0005).2 In conclusion, future goal-directed hemodynamic therapy research should focus specifically on high-risk surgical patients, both within and outside enhanced recovery pathways.
Dr. Ripollés-Melchor received travel funding from Deltex Medical (Chichester, United Kingdom) and honoraria for lectures from Fresenius Kabi (Bad Homburg, Germany), Edwards Lifesciences (Irvine, California), Deltex Medical, and Merck Sharp & Dohme (Kenilworth, New Jersey). He is currently the Chief of Fluid Management section of Grupo Español de Rehabilitación Multimodal (GERM/ ERAS Spain Chapter; Zaragoza, Spain). Dr. Aldecoa declares no competing interests.