The present study found that EDIA not only achieved higher and faster total daily energy and protein intake significantly throughout the hospitalization period but also experienced less weight and muscle depletion compared DDIA. The prolonged preoperative fasting period was diminished by preoperative CHO loading with a whey protein-infused CHO drink and postoperative early oral feeding thus changed the body from a ‘fast’ state to ‘fed’ state [16]. EDIA initiated earlier postoperative oral feeding as per ERAS recommendation. Majority of EDIA received intensive nutritional intervention where they were not only received the energy-dense clear fluid ONS preoperative 3-hours but also energy-dense clear fluid ONS postoperative once started clear fluid and followed by energy-dense complete ONS after allowing solid diet while most of DDIA received plain water after allowed for clear fluid, nourishing fluid and followed by soft diet [29]. Postoperative intensive nutritional intervention management aimed to prevent nutritional depletion due to negative energy protein balance, maintain an appropriate nutritional status to support rehabilitation and wound healing [31]. The integration of energy- and protein-dense ONS into postoperative nutritional intervention regime intended to secure protein and energy intake while the oral intake was building [2].
The current finding was similar to the results from studies by Yeung and colleagues and Brown and colleagues where adequate energy and protein intake during the perioperative period prevent nutritional depletion and promote a speedy recovery[34]. Postoperative suboptimal energy protein intake increases the nutritional depletion rate if there was no further nutritional intervention to be carried out [31]. Therefore, the free unrestricted diet was recommended from 4 hours post-operation and ONS should be provided to ensure adequate postoperative energy and protein intake [23]. The postoperative patients, who were rapidly progressed to standard diet immediately after 500ml clear fluid toleration, achieved higher energy protein intake compared with those under slow progression conventional transition diet, with no significant increase complication rate [10]. This indicated postoperative early oral feeding and rapid progression to a normal diet after tolerating clear fluid hastened diet toleration time boosted up postoperative total daily energy and protein intake as well as cut down the reliance on ONS [4]. In addition, ICU admission showed that affected negatively and delayed the postoperative dietary intake might due to clinically hemodynamic unstable to initiate feeding and experienced dysphagia after extubation [25]. Present study also demonstrated that the operation time influences postoperative dietary achievement. Longer duration of operation is usually associated with more complex operations, higher complications and prolonged recovery as well as delayed postoperative dietary intake [9].
Dietary energy and protein intake were correlated with body composition including muscle mass. Inadequate oral intake might extend the catabolic response and further deplete the nutritional status post-operation [26]. The prolonged inadequate oral intake and hypercatabolic trigger skeletal muscle degradation [14, 24]. Therefore, postoperative total daily energy and protein intake determine protein metabolism and muscle wasting. These approaches minimize the energy protein negative balance, provide early energy protein supply, reduce protein loss, improve muscle function, and promote the anabolic state. Preservation of postoperative weight loss and muscle wasting could be achieved by minimizing body glycogen breakdown, glucose synthesis from protein or fat, and fat oxidation [29]. The body composition and handgrip strength conservations might result from the combined effect of shortening of preoperative fasting and postoperative early feeding. Henrikson and colleagues also concluded that patients with preoperative CHO plus protein loading acquired greater muscle strength [11]. Beattie and colleagues identified that a greater extent of muscle function preservation to those close to preoperative levels with early oral feeding with ONS [3].
In the present finding, there are four statistically significant independent predictive factors related to postoperative dietary intake achievement on postoperative day-two among surgical GC patients which including age, pre-operative whey protein-infused CHO loading, presence of postoperative nausea and vomiting, and time to start clear fluid. Age influences post-operation dietary intake and tolerance. Old age was demonstrated as a risk factor of postoperative severe malnutrition [18]. Another study also revealed that old age and female patients were significantly associated with delayed postoperative oral toleration. This finding might be due to old female patients are more perceptive to gastrointestinal discomfort while initiating oral intake post-operation. They favor to resume and increase oral intake gradually as compared with male or younger patients [15]. There was a study showed that geriatric patients experienced a higher risk of being malnourished post-operation [18]. Hence, postoperative intensive nutrition management with providing ONS was suggested among geriatric surgical patients to increase dietary energy and protein intake, prevent further nutritional depletion and shorten the duration of hospital stays [31].
PONV is a common reason for delayed functional recovery[22]. Anorexia or loss of appetite is a common reason for postoperative inadequate dietary intake related to gastrointestinal dysfunction and postoperative pain. Severe PONV, salivary secretion reduction, and change in taste could be induced by intubation, anesthesia, and surgery-related inflammation after the abdominal major surgery [17]. PONV was shown to be reduced with preoperative CHO loading[6]. ERAS study in gynecological oncology showed that postoperative early oral feeding lessened abdominal distension, postoperative nausea, and vomiting and also hasten gastrointestinal recovery [19]. The fear of PONV and food preference might cause self-delay postoperative feeding [27]. The patient-centered dietary approach, which included anti-emetics and prescription of unrestricted diet, may have assisted in commencing feeding. The early nutrition assessment to detect insufficient dietary intake and intensive nutrition intervention to optimize dietary intake were recommended postoperatively. Intensive and individualised postoperative nutrition intervention improves dietary intake, enhance functional recovery, and prevent further nutritional depletion[24].
The present finding demonstrated that preoperative whey protein-infused CHO loading and time to start clear fluid boost up the postoperative dietary intake. As per evidenced based ERAS recommendation, preoperative CHO loading lessened PONV and improved postoperative oral toleration [28, 34]. Postoperative early oral feeding, where initiated clear fluid ingestion 4–6 hours post-operation as one of the elements of ERAS recommendation [16], stimulates the early dietary intake and toleration in virtue of accelerating intestinal function recovery and prevents the occurrence of peristalsis of the stomach and small intestine and irregular contraction waves resulted from prolonged fasting. Thus, the intestinal mucosal barrier function could be maintained, and further accelerating organ recovery[29]. Preoperative CHO loading was shown a positive impact in minimizing insulin resistance and catabolism of muscle mass and subsequently resulted in the minimisation of postoperative complications and preservation of nutritional status and muscle strength [28]. Yamada and colleagues also reported that the preoperative CHO loading ensured better body weight preservation [33].
Current results did not show the correlation between preoperative nutritional status and postoperative dietary intake achievement. The perioperative nutrition approaches in the ERAS protocol (preoperative CHO loading and postoperative early oral feeding), PONV management, and age showed a greater impact on the postoperative dietary intake than preoperative malnutrition. Hence, the role of dietitian-led nutritional intervention after a major operation has been demonstrated that improved energy and protein intake. Perioperative dietitian-led nutritional management is crucial to optimize nutritional status [30]. Other than nutritional intervention management immediate post-operation, individualized intensive nutritional intervention management with integration of ONS upon discharge is an essential element to be provided and explained to the patients and caregiver to achieve energy protein requirement and promote postoperative recovery [7].
Strength and Limitations
The present study was the first study to demonstrate postoperative nutritional achievement as well as investigate the predictors of postoperative dietary intake achievement among GC patients in Malaysia. However, the current study did have a few limitations. This was a single-center study observation that focused on surgical GC patients who underwent elective operation only. Thus, the predictive model may not suit other surgical cancer patients. The model might become more superior if there are various types of cancer patients from multicentre involvement. Last but not least, the selection bias might be happened due to the operation may not be offered to those who non-operable GC and the severely malnourished patients.