Introduction

Oral cancer represents a clinically prevalent malignant tumor of the head and neck region, ranking as the sixth most common malignancy worldwide1, with its incidence demonstrating a persistent upward trend. Current therapeutic strategies primarily involve radical resection combined with concurrent flap reconstruction2. Nevertheless, such extensive surgical interventions frequently result in compromised masticatory and swallowing functions, leading to inadequate nutritional intake, delayed systemic recovery, and heightened susceptibility to postoperative complications. Research has demonstrated that oral cancer patients frequently experience malnutrition both preoperatively and postoperatively, and this nutritional deficiency has emerged as a critical independent factor influencing the incidence of postoperative complications in this population3.

Enteral nutrition (EN) is the delivery of nutrients to patients via the digestive tract. It can be categorized as either tube feeding (TF) or oral nutritional supplements (ONS), depending on the specific route of administration4. Extensive research has been conducted on early enteral nutrition in patients undergoing open surgery, with favorable outcomes demonstrated in previous studies5. Current evidence indicates that the implementation of early postoperative enteral nutrition not only enhances immune resistance and improves nutritional status through gastrointestinal function optimization6,7, but also significantly reduces the incidence of postoperative complications. Furthermore, this nutritional strategy facilitates clinical recovery and shortens hospital stays8. Currently, there is a lack of standardized protocols for early enteral nutrition management in patients undergoing flap reconstruction for oral cancer. Therefore, it is imperative to develop a scientific and rational management protocol that provides comprehensive and holistic enteral nutritional support for postoperative oral cancer patients, thereby improving their nutritional status and clinical outcomes.

The Delphi method is a widely utilized prediction and evaluation approach that integrates quantitative and qualitative methodologies. During implementation, this technique employs an anonymous iterative process to systematically collect expert opinions through multiple rounds of consultation, effectively mitigating potential bias caused by dominant personalities or hierarchical influences among authoritative experts9.

Therefore, this study adopted an evidence-based approach to develop a scientifically valid and clinically effective early postoperative enteral nutrition protocol for oral cancer patients undergoing flap reconstruction through Delphi expert consultation. The application effect was preliminarily explored, providing evidence-based support for early enteral nutrition in this surgical population, and providing methodological references for similar studies.

Methods

Development of an early enteral nutrition protocol for oral cancer patients undergoing flap reconstruction

Establishment of the research team

A research team comprised of four members was organized to develop an early enteral nutrition protocol. The team consisted of one head nurse of oral and maxillofacial surgery, one clinical nurse specializing in oral and maxillofacial surgery, and two nursing master’s degree candidates. The primary responsibilities of the research team included: (1) Conducting systematic literature searches and screening relevant studies; (2) Performing quality assessments of retrieved literature based on study design and extracting pertinent data; (3) Synthesizing evidence, grading its level, and drafting the preliminary protocol; (4) Designing Delphi consultation questionnaires, selecting expert panelists, and administering the consultation process; and (5) Consolidating expert feedback and conducting statistical analysis of the collected data.

Theoretical framework

In 2003, the Academy of Nutrition and Dietetics (AND) developed the Nutrition Care Process and Model (NCPM), a standardized and systematic framework designed to enhance care quality and improve patients’ nutritional status. The NCPM comprises four interrelated yet distinct phases: nutrition assessment and reassessment, nutrition diagnosis, nutrition intervention, and nutrition monitoring and evaluation. The first two components focus on problem identification, while the latter two emphasize problem resolution10. Evidence-based studies have demonstrated that the implementation of the NCPM significantly improves the resolution rate of nutrition-related issues and enhances patients’ quality of life11.

Literature search

A systematic literature search was conducted according to the “6S” evidence hierarchy model. Keywords included “oral cancer/oral cavity cancer/oral cavity tumours,” “flap reconstruction/flap transplantation,” “enteral nutrition/nutrition enteral/enteral feeding/feeding enteral/tube feeding/feeding tube/enteral tube feeding/nasogastric feeding/gastric tube”. Databases and resources spanned evidence-based platforms (UpToDate, BMJ Best Practice, Joanna Briggs Institute [JBI], National Institute for Health and Care Excellence [NICE], Registered Nurses’ Association of Ontario [RNAO], American Cancer Society [ACS], Scottish Intercollegiate Guidelines Network [SIGN], Guidelines International Network [GIN], National Guideline Clearinghouse [NGC], National Comprehensive Cancer Network [NCCN]), biomedical databases (PubMed, Web of Science, Embase, Cochrane Library, CINAHL), and Chinese repositories (CNKI, Wan fang Database, VIP, SinoMed, and Medlive). The search timeframe covered records from database inception to 2024. Eligible publication types included clinical guidelines, expert consensuses, evidence summaries, systematic reviews, randomized controlled trials (RCTs), and quasi-experimental studies. After rigorous screening, 13 articles were ultimately retained, including 6 guidelines12,13,14,15,16,17, 1 expert consensus18, 1 evidence summary19, 1 systematic review20, and 4 RCTs21,22,23,24. The retrieved evidence informed the preliminary draft of the protocol.

Delphi expert consultation

Questionnaire development

The questionnaire comprised four sections: (1) Introduction: Presenting the research background, objectives, and significance; (2) Expert Demographics: Collecting baseline information including gender, age, educational background, professional title, position, years of experience, research field, and contact details; (3) Delphi Evaluation Form: Assessing hierarchical indicators through importance and feasibility ratings (5-point Likert scale: 1 = “extremely unimportant/unfeasible” to 5 = “extremely important/feasible”), incorporating a comment field for modifications and detailed completion guidelines; (4) Expert Self-Assessment: Evaluating participants’ familiarity with the research topic and documenting the sources of judgment influencing their evaluations (e.g., theoretical analysis, practical experience).

Expert selection

Expert selection criteria were established as follows: (1) Employment at tertiary Grade-A hospitals; (2) Minimum educational qualification of bachelor’s degree; (3) ≥ 10 years of clinical experience in oral healthcare (clinical practice/nursing) or equivalent duration in clinical administration/nursing education/scientific research; (4) Intermediate-level or higher professional title; (5) Demonstrated familiarity with the research field and voluntary participation agreement.

The Delphi panel ultimately comprised nine experts. Academic qualifications included 1 doctoral candidate, 4 master’s degree holders, and 4 bachelor’s degree holders. Professional titles consisted of 1 senior professional title, 7 associate senior titles, and 1 intermediate title. The mean age was (43.00 ± 4.36) years (range: 35–50 years), with an average work experience of (20.44 ± 6.64) years (range: 10–30 years).

Implementation of expert consultation

The questionnaires were distributed and collected via email or WeChat (a prevalent instant messaging platform in China). Through Delphi consultation, the early enteral nutrition protocol underwent rigorous evaluation. The intervention protocol was systematically refined based on expert feedback regarding content validity and implementation feasibility, ultimately enhancing its clinical operability and scientific robustness.

Expert engagement and authority

Expert engagement was quantified by the valid questionnaire response rate, with a threshold > 70% indicating a high level of engagement. Expert authority was assessed through the authority coefficient (Cr), calculated based on two dimensions: the self-assessed familiarity coefficient (Cs) and rationale of judgments (Ca). A Cr value ≥ 0.7 was considered acceptable reliability, while Cr > 0.8 denoted high expert authority25. In this study, the expert consultation achieved a 100% valid response rate, with calculated coefficients of Ca = 0.956, Cs = 0.867, and Cr = 0.912, collectively demonstrating exceptional methodological credibility and authoritative consensus.

Expert recommendations and protocol revisions

The expert panel proposed eleven modification recommendations: (1) Inclusion of pharmacists and medical engineers in the multidisciplinary team; (2) Expansion of dietary survey parameters to incorporate additional factors influencing nutritional intake; (3) Implementation of regular training and competency assessments for multidisciplinary team members; (4) Dynamic adjustment of interventions based on hospitalization duration, nutritional status, and recovery progression; (5) Enhanced strategies for activating patient self-efficacy; (6) Consideration of nasojejunal tube placement for patients with high aspiration risk; (7) Standardized monitoring protocols for gastrointestinal function and enteral tolerance; (8) Optimization of psychological intervention components; (9) Strategic timing refinement with preoperative oral nutritional supplementation; (10) Integration of comprehensive nutritional assessment criteria; and (11) Establishment of competency benchmarks for multidisciplinary team qualifications. Following rigorous discussion by the research committee, all recommendations were adopted. The protocol underwent systematic revision, culminating in the finalized early enteral nutrition protocol for oral cancer patients undergoing flap reconstruction (Table 1).

Table 1 Early enteral nutrition protocol for oral cancer patients undergoing flap reconstruction.
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Preliminary application of early enteral nutrition protocol in oral cancer patients undergoing flap reconstruction

Study subjects

Patients who underwent oral cancer resection with flap reconstruction surgery at a tertiary Grade-A hospital in Shandong Province between December 2023 and May 2024 were enrolled. Inclusion criteria comprised: (1) Histopathologically confirmed oral carcinoma requiring surgical resection with concurrent flap reconstruction; (2) Aged ≥ 18 years without major organ dysfunction (cardiac, hepatic, or renal); (3) Absence of preexisting gastrointestinal disorders, diabetes mellitus, or nutrition-related metabolic comorbidities; (4) Willingly provided written informed consent for study participation. Exclusion criteria included: (1) Concomitant malignancies; (2) Cognitive impairments or psychiatric disorders precluding protocol adherence. The Ethical Committee of Shandong Provincial Hospital Affiliated to Shandong First Medical University approved this study (Ethic-SWYX: NO. 2023-1017-1). All participants provided documented informed consent prior to enrollment.

Research methodology

Multidisciplinary team formation

Consistent with the developed protocol, a multidisciplinary nutritional support team was established for the patients in this study.

Nutritional risk screening and assessment

Within 24 h of admission, patients underwent NRS-2002 screening by research nurses. Patients identified as being at nutritional risk received a comprehensive nutritional assessment to determine their nutritional status.

Nutritional diagnosis

Energy, protein, lipid, and glucose requirements were determined under the guidance of dietitians and clinicians, synthesizing data from dietary surveys, anthropometric measurements (midarm circumference, triceps skinfold thickness), laboratory analyses (prealbumin, transferrin), clinical history, and confounding factors affecting nutritional intake.

Nutritional intervention

Malignant tumor patients choose ONS 7–10 days before surgery to improve nutritional status and then proceed with surgery immediately. Postoperative enteral nutrition commenced within 24 h postoperatively via protocol.

Strict adherence to evidence-based enteral nutrition (EN) support protocols was maintained. Specific plans include: On the first postoperative day, nasogastric feeding of 500 ml of enteral nutrition solution at a drip rate of 25–50 ml/h, on the second postoperative day, nasogastric feeding of 1000 ml of enteral nutrition solution at a drip rate of 50–100 ml/h, and from the third postoperative day onwards, daily nasogastric feeding of 1500 ml or more of enteral nutrition solution at a drip rate of 100–125 ml/h. Temperature control: nutrient solution temperature was maintained at 38–40 °C using a medical-grade heating device. Positioning: head-of-bed elevation was maintained at 30–45° during infusion. Tube maintenance: 20–30 mL warm water flushing was performed both before/after feeding interruptions and medication administration. Scheduled maintenance: routine irrigation with 20–30 mL warm water every 4 h during continuous infusion. At the same time, provide psychological care for patients to improve treatment compliance.

Nutritional monitoring and evaluation

Nutritional parameters (TP, ALB, and Hb) and inflammatory markers (WBC and ANC) were analyzed at T0 (preoperative day 1), T1 (postoperative day 1), and T2 (postoperative day 7). Secondary outcomes included postoperative complications and hospitalization duration.

Statistical methods

Statistical analyses were performed using SPSS 25.0. Normally distributed continuous variables were presented as mean ± standard deviation (SD), while categorical variables were expressed as frequencies and percentages (%). Repeated-measures ANOVA was employed to compare longitudinal changes in outcome measures across different time points. A two-tailed P value < 0.05 was deemed statistically significant.

Research results

Baseline characteristics

The study included 35 patients, comprising 23 males (65.7%) and 12 females (34.3%), with a mean age of 60.74 ± 13.50 years. The distribution of cancer types was as follows: gingival carcinoma (n = 4, 11.4%), tongue carcinoma (n = 4, 11.4%), floor-of-mouth carcinoma (n = 5, 14.3%), jaw carcinoma (n = 12, 34.3%), buccal carcinoma (n = 3, 8.6%), palatal carcinoma (n = 4, 11.4%), and parotid gland carcinoma (n = 3, 8.6%).

Changes in nutritional parameters

A longitudinal assessment of nutritional parameters was conducted at three time points in 35 patients, with repeated-measures ANOVA applied to evaluate dynamic changes in ALB, TP, and HB levels. Baseline measurements (T0) revealed mean values of 34.68 ± 7.07 g/L for ALB, 58.82 ± 12.19 g/L for TP, and 113.20 ± 23.37 g/L for HB. During the initial post-intervention phase (T1), all parameters exhibited a declining trend (ALB: F = 89.508; TP: F = 26.506; HB: F = 36.242; all P < 0.05). In the later intervention stage (T2), significant increases in these nutritional parameters were observed compared to T1 (P < 0.05), indicating that the nutritional interventions produced significant improvement effects in the later phase (Table 2, Fig. 1).

Table 2 Changes in nutritional indicators at different time points (x¯ ± s, n = 35). a, precise statistics.
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Fig. 1
figure 1

The trend of changes in nutritional indicators at different time points.

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Changes in inflammatory markers

Serial monitoring of inflammatory markers—WBC and ANC—was performed at three time points in 35 patients. Comparative analysis revealed significant increases in both WBC and ANC levels at T1 compared to baseline (T0) (P < 0.05), indicating a pronounced acute inflammatory response during the early postoperative phase. Subsequent analysis demonstrated marked reductions in these parameters at T2 relative to T1 (P < 0.05), consistent with progressive resolution of systemic inflammation. Notably, despite the observed declines from T1 to T2, biomarker levels at T2 remained statistically elevated compared to preoperative baselines (T0) (P < 0.05), suggesting incomplete restoration of inflammatory homeostasis by postoperative day 7 (Table 3, Fig. 2).

Table 3 Changes in inflammatory markers at different time points (x¯ ± s, n = 35). a, precise statistics.
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Fig. 2
figure 2

The trend of changes in inflammatory markers at different time points.

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Hospitalization time and complications

The mean hospital stay duration was (10.11 ± 2.41) days. Postoperative complications occurred in three patients (8.57% incidence rate) during hospitalization, including one case of flap crisis and two cases of pulmonary infection.

Discussion

The results of this study demonstrated that ALB, PA, and Hb levels on postoperative day 7 were significantly higher than those on postoperative day 1 (p < 0.05), suggesting that the early enteral nutrition protocol implemented in this cohort was more effective in improving patients’ nutritional status. In oral cancer patients, surgical trauma, stress responses, and postoperative dietary restrictions collectively contribute to a hypercatabolic state, leading to accelerated depletion of protein and caloric reserves. Early enteral nutritional support may mitigate these effects by replenishing essential nutrients, enhancing protein anabolism, and maintaining serum protein homeostasis, thereby providing critical energy and nutritional substrates to facilitate postoperative recovery.

In terms of immune function, patients exhibited transient immunosuppression during the early postoperative phase. However, progressive recovery of immune parameters was observed with sustained enteral nutritional support. This phenomenon may be attributed to the nutrient composition of the administered formula, including proteins, vitamins, and trace minerals, which provide essential substrates for the proliferation and functional maintenance of immune cells. Furthermore, these nutrients may enhance systemic immune defense mechanisms, thereby potentially reducing the incidence of infectious complications and improving clinical outcomes.

The low incidence of complications observed in this study may be associated with the improvements in nutritional status and immune function mediated by early enteral nutritional support. Optimal nutritional status is a critical determinant of postoperative recovery and complication risk. Adequate nutritional support enhances immune competence, facilitates wound healing, and reduces the risk of complications such as anastomotic leakage and surgical site infection. Additionally, enteral nutrition preserves intestinal mucosal integrity and maintains gut barrier function, thereby mitigating bacterial translocation and subsequent systemic infections (e.g., pulmonary infections). Furthermore, early enteral feeding accelerates the recovery of gastrointestinal motility, which may further reduce the incidence of gastrointestinal-related complications.

Early enteral nutritional intervention enables timely nutrient supplementation during the critical postoperative phase, enhances protein synthesis, and maintains physiological metabolic homeostasis. The elevation of nutritional biomarkers such as serum albumin provides the substrate for tissue repair and sustains immune competence. Furthermore, improved nutritional status accelerates postoperative recovery trajectories, thereby shortening hospitalization duration. This reduction in hospital stay not only alleviates psychological and physical burdens on patients but also reduces the economic burden on patients and optimizes healthcare resource utilization.

The limitations of this study are mainly reflected in the small sample size and nonrandom grouping method. Due to limited sample size, some results may not be clear enough, and nonrandom grouping methods may lead to selection bias. Furthermore, this study focused on the perioperative period, so no formal follow-up was conducted after the patient was discharged. Future research should consider expanding the sample size, adopting a prospective randomized controlled trial design, and including long-term follow-up to comprehensively evaluate its long-term application effect in fibular free flap surgery for oral cancer patients. Despite these constraints, this work provides preliminary evidence supporting early enteral nutrition implementation.

Conclusion

The early enteral nutrition protocol developed for oral cancer patients undergoing flap reconstruction in this study has been preliminarily validated to effectively improve nutritional status, reduce complication rates, shorten hospitalization duration, and promote postoperative recovery. However, the limited sample size and short-term follow-up period necessitate further validation through large-scale, multicenter randomized controlled trials (RCTs) to evaluate the long-term efficacy and safety of this protocol. Such investigations may contribute to refining evidence-based nutritional support strategies for optimizing clinical outcomes in oral cancer management.