It's the colloid, not the esophageal Doppler monitor.

Abstract

To the Editor:—The debate over whether crystalloid or colloid is a better replacement fluid in the perioperative period has been of interest for decades. Gan et al. 1have introduced new data in this debate with their study of 100 patients undergoing major elective surgery with an anticipated 500-ml blood loss. The authors used esophageal Doppler monitor (EDM)-guided colloid administration to improve preload, cardiac output, tissue perfusion, and patient outcome in the treatment group.In effect, the treatment group has two variables: use of the EDM and use of colloid boluses. The EDM provided guidance for “goal-directed” fluid therapy. Although the EDM may not give an accurate measurement of preload or cardiac output, 2,3as a clinical monitor it enables an assessment of changes in corrected flow time and preload. With regard to the use of colloid boluses, the treatment group received 200 ml of 6% hydroxyethyl starch in saline every 15 min to maximize corrected flow time and stroke volume. The control group received 200-ml “fluid” boluses (more likely crystalloid) to treat changes in hemodynamic parameters (heart rate, blood pressure, central venous pressure) or decreased urinary output.The better outcomes in the treatment group can be attributed solely to those patients receiving 847 ml of hydroxyethyl starch compared to 282 ml for the control group. Both groups received 4400 ml of lactated Ringer's solution during roughly 4 h of surgery. Other studies have demonstrated that EDM-guided use of supplemental colloid boluses in cardiac 4and orthopedic surgical patients 5was associated with improved outcomes, including shorter hospital stays. Taken together, the three studies demonstrate significantly improved patient outcomes when larger amounts of colloid were given to patients in the treatment group.An esophageal Doppler monitor costs $8000, with an additional $100 for each esophageal probe (verbal communication, Deltex Medical, Branford, Connecticut, October 2002). The EDM provides a better assessment of preload than does a pulmonary artery or central venous catheter, 6but contrary to the BBC interviews 7that resulted from the present study, we suggest that none of these three methods may be required to achieve the benefits of earlier return to bowel function, lower incidence of postoperative nausea and vomiting, and decrease in length of postoperative hospital stay. Based on the findings of Gan et al. , we suggest that the intraoperative administration of 500–1000 ml of hydroxyethyl starch will provide a more cost-effective patient benefit for relatively healthy patients, without significant cardiovascular disease, who are undergoing major elective surgery.We agree with the authors that “intraoperative fluid augmentation appears to confer significant benefits compared with customary practice.” Further investigation is required to test whether additional colloid administration without the use of EDM would result in similar patient benefits, because Gan et al. do not directly address this issue. Crystalloid or colloid? The results of this study imply that administration of both may improve patient outcomes after major elective surgery.