In this prospective randomized study, we compared outcomes in elderly patients undergoing open gastrointestinal surgery that were treated via traditional standard of preoperative fasting and CFT or via perioperative fluid optimisation including preoperative carbohydrate load and intraoperative GDFT. This analysis revealed that the latter was associated with more rapid restoration of bowel function and with a lower rate of postoperative complications.
For the present study, we specifically analyzed outcomes in elderly patients undergoing open gastrointestinal surgery for two reasons. First, elderly patients with gastric or colorectal cancer have high rates of comorbidities that are associated with increased surgical risk . Second, unlike laparoscopic surgery, open gastrointestinal surgery is associated with large changes in intraoperative fluid levels , and as such poor organ perfusion or fluid overload have the potential to lead to poorer surgical outcomes. Further study of optimal care techniques for elderly patients undergoing major abdominal surgery is needed, and as such in the present study we sought to determine whether the reduction of the time for preoperative fasting and GDFT was able to improve clinical outcomes in these patients.
For this study, we opted to utilize CI rather than the oxygen delivery index as the key target variable for our GDFT protocol as it can be readily and continuously monitored via radial artery pulse waveform analysis. When arterial oxygen saturation and hemoglobin levels are adequate, CI can serve as an effective means of evaluating oxygen supply within tissues and organs . As the use of CI and SVV with the Vigileo/FloTrac monitor has been found to be potentially unreliable in patients with irregular heart rhythms [21, 26] and in patients with poorly controlled intraoperative ventilation , we did not include patients with severe arrhythmia in the present study, and all patients were ventilated using a tidal volume of 8 ml/kg.
Excess fluid transfusion can result in a range of problems including increased rates of postoperative cardiac morbidity, pneumonia, respiratory failure, delayed wound healing, and anastomotic leak as a consequence of intestinal edema in patients undergoing colorectal surgery . As shown in some prior trials [16, 25, 28], our study also found that the GDFT protocol is associated with reductions in the rate of postoperative complications. In addition, the lower incidence of postoperative infection complications in the GDFT group may also be related to preoperative oral carbohydrate loading, which may reduce the metabolic and inflammatory response after surgery and improved surgical clinical outcomes . However, the rates of postoperative complications in some previous studies were higher than in our present analysis. There are two potential reasons for this discrepancy. For one, Mayer et al.  selected high-risk patients with at least two risk factors according to risk index of Lee  as their experimental subjects. Furthermore, Benes et al.  recruited patients that had to meet both operation-related and patient-related high-risk criteria. In contrast, all patients we included were over the age of 65, some of whom may be in the low-to-moderate risk category. In addition, we only monitored the incidence of postoperative complications that occurred during hospitalization, whereas Benes et al. monitored patients for 30 days . Together, our results suggest that perioperative fluid optimisation reduces the incidence of postoperative complications in elderly patients, rather than only in high-risk patients.
The relationship between GDFT and the duration of postoperative hospitalization remains controversial. Early studies found GDFT to be associated with a reduction in the duration of postoperative hospitalization , but this finding was not repeated in more recent studies , particularly in studies performed in an ERAS (enhanced recovery after surgery) setting [2, 32]. The increased application of ERAS protocols has led to improvements in the quality of perioperative care in control groups over the past 15 years, potentially influencing these study results . However, hospitalization duration can also be influenced by a range of other factors such as patients’ wishes, preoperative physical condition, health care system requirements, and institution-specific differences in treatment regimens. All of these factors thus have the potential to influence the relationship between GDFT and postoperative hospitalization duration.
Given that it is a sensitive indicator of organ perfusion, arterial lactate levels are closely linked to tissue hypoxia and blood volume insufficiency . In the context of suboptimal fluid management, postoperative restoration of gastrointestinal motility and oral food intake may be delayed due to higher lactate levels. While at baseline in the present study we found that lactate levels were higher in the GDFT group relative to the CFT group, we did not observe any significant differences between these values at analyzed time points. However, we did find that lactate values in the CFT group increased at the end of surgery relative to baseline values. The slower recovery of bowel function observed in the CFT group may thus be associated with increased lactate production.
Urine output is typically utilized to approximate renal function and blood volume. In this study, we found that patients in the GDFT treatment group required reduced crystalloid administration and exhibited reduced urine output relative to patients in the CFT group. Postoperative renal failure occurred in one patient in the GDFT group and two patients in the CFT group. This outcome may be explained by work conducted by Kheterpal et al , as these authors suggested that urine is unreliable when used as a marker of blood volume and renal function, given that it can be influenced by neurohormonal signaling in response to operative stress. The administration of diuretics and vasoactive agents has also been linked to the incidence of acute renal failure.
There are multiple limitations to the present analysis. For one, in an effort to avoid potential compounds we did not utilize the CI and SVV trending monitor for patients in the CFT group, so we were not able to compare these parameters between groups. Moreover, we were not able to blind investigators intraoperatively to patient treatment strategies. Additionally, intraoperative attending anesthesiologists were the primary focus of this study. The professional level of the attending anesthesiologists and physicians for postoperative treatment in the ICU and hospital wards should be equivalent between groups. Otherwise, it is possible that higher rates of postoperative complications may result from poorer postoperative care in the CFT group. Lastly, we did not pre-define standardized discharge criteria in the present study, as discharge may be influenced by a range of factors including patient demands, health care system capacity, and specific treatment regimens used. Thus, the duration of postoperative hospitalization could be also biased.