Preoperative carbohydrate loading and perioperative fluid optimization significantly improved bowel function with a reduced risk of post-surgery complications in the elderly population undergoing gastrointestinal surgery. 

Elderly population (≥ 65 years old) are more susceptible to develop an extensive range of pharmacological, psychological, and physical comorbidities that healthcare professionals and anesthesiologists should consider before undergoing any necessary surgery. Advanced age is an essential risk factor that significantly increases morbidity and mortality following any surgery. Also, older adults are more vulnerable to develop detrimental effects such as hypovolemia, dehydration, and hemodynamic instability stimulated by extended fasting.

Intraoperative hypovolemia further leads to severe post-surgery complications such as arrhythmia and hypotension, whereas hypervolemia causes other significant troubles like pulmonary edema, anastomotic leaks, infection, or even mortality. Both excess and insufficient infusion is harmful to patients. Further age-associated decrease in organ function and difficulty adjusting fluid preloading also increases the risk of post-surgery death in elderly people.

The major aim of preoperative fluid therapy is to prevent dehydration or hypovolemic state before inducing anesthesia in patients. Thus, the multiple Enhanced Recovery After Surgery (ERAS) guidelines focus on the oral consumption of carbohydrate loading (200 ml) two hours before surgery, which may reduce the post-surgery complications like wound infection and post-surgery nausea and vomiting. Furthermore, routine hemodynamic estimations (like heart rate or arterial blood pressure) are commonly an inaccurate way of supervising the alterations in blood volume.

On the contrary, goal-directed fluid therapy (GDFT) relies on supervising more advanced hemodynamic variables like stroke volume variation and pulse pressure variability that have more sensitivity to hypovolemia and thus permit optimal preloading by allowing medical care professionals to titrate fluids and inotropic substances adequately. As a result, GDFT has been found to shorten the duration of hospitalization and the occurrence of post-surgery complications by 20-50% in previous systematic reviews.

Few studies have determined if the preoperative carbohydrate loading combined with intraoperative GDFT was beneficial in elderly people. Therefore, in this trial, fluid optimization was carried out in elderly people using hemodynamic indicators (cardiac index [CI], stroke volume variation, mean arterial pressure) and vasoactive drugs, as needed. It was assumed that the preoperative carbohydrate loading and intraoperative GDFT based upon hemodynamic indicators might shorten the post-surgery hospitalization and complications in elderly people undergoing an open gastrointestinal operation.

Rationale behind research

The effect of combination of GDFT and preoperative carbohydrate loading on post-surgery complications in elderly people is still unclear. Thus, this prospective randomized controlled trial was performed.

Objective

This study examined the relative influence of preoperative carbohydrate loading and intraoperative GDFT vs conventional fluid therapy (CFT) on the clinical outcomes in elderly people after the gastrointestinal operation. 

Study outcomes

• The primary endpoint was the comparison of complications between the groups
• The secondary outcomes include evaluation of postoperative outcomes such as time to first flatus, time to first oral intake, postoperative hospitalization, amount of hospital charges, admission to intensive care unit, and postoperative mortality
• Other outcomes included evaluation of intraoperative outcomes and concentrations of lactate in the blood

Outcomes

Baseline: There were no vital differences reported at baseline.

Study outcomes

• A significant decline was observed in the rate of post-surgical complications among the GDFT group when compared with the CFT group (25% vs 48.3%) (Figure 2)
• The average time to initial flatus (56 ± 14.1 h vs 64 ± 22.3 h) and oral intake (72 ± 16.9 h vs 85 ± 26.8 h) were reduced in the GDFT group compared to the CFT group
• The urine output (200 ml [150–300] vs 400 ml [290–500]) and the need for crystalloids fluid (1111 ± 442.9 ml vs 1411 ± 412.6 ml) were lowered among participants in the GDFT group compared to participants in the CFT group
• The post-surgery hospitalization or hospitalization expenses were comparable between both study groups

The combination of preoperative oral carbohydrate loading and intrasurgery ERAS seems valuable for the medical care practice due to their beneficial effects on post-surgery outcomes. The GDFT showed a considerably faster restoration in bowel function and a reduced rate of post-surgery complications than the standard of care group.

The study findings also reported that the duration of hospitalization duration might be affected by a range of factors like preoperative physical condition, patients' wishes, health care system needs, and institution-specific differences in the therapeutic regimens. All these factors may potentially impact the relationship between GDFT and post-surgery hospitalization duration. As found, the interventions may have more impact on the rate of post-surgery complications compared with the length of hospitalization. Therefore, the rate of post-surgery complications was determined as the primary endpoint, and length of hospitalization was selected as the secondary endpoint.

In this trial, the CI was utilized as the critical target variable for the GDFT protocol rather than the oxygen delivery index as it can promptly and continuously be supervised via the radial artery pulse waveform assessment. In addition, CI can also serve as the most valuable parameter to investigate oxygen supply within the organs and tissue; when there are adequate levels of haemoglobin and arterial oxygen saturation. Since the utilization of CI and stroke volume variation with the Vigileo/FloTrac monitor has been noted to be unreliable in people having irregular heart rhythms and poorly controlled intrasurgery ventilation, the investigators did not incorporate people without sinus rhythm, and all the participants were ventilated utilizing a tidal volume of 8 ml/kg.

Excess administration of fluid can lead to an array of problems, including elevated rates of post-surgery cardiac morbidity, delayed wound healing, pneumonia, respiratory failure, and anastomotic leak resulting from intestinal edema in patients undergoing colorectal surgery. However, similar to the findings of few prior trials, this trial also noted that the GDFT protocol is related to a decline in the rate of post-surgery complications. Furthermore, no profound differences were noted in the arterial values at different time points among the study groups. But, an increase in the lactate values was observed in the CFT group postoperatively compared to the baseline values.

Following major abdominal surgery, the intrasurgery reduced urine output is an independent predictor of acute kidney injury. Subjects in the GDFT therapy group required less crystalloid and had reduced urine output than subjects in the CFT group, as observed in this study. But, postoperative acute kidney injury was observed in two people in the CFT group and one individual in the GDFT group. The intraoperative GDFT appeared to reduce the risk of post-surgery acute kidney injury than the restrictive regimen. However, additional larger, higher-quality research is warranted in the future.