Lung resection, a critical treatment for various thoracic diseases, including lung cancer, often necessitates prolonged hospitalization due to rare but severe postoperative complications such as chyle leaks, with an occurrence of 0.25%-3%, prolonging chest drainage, and delaying recovery. Therefore, effective postoperative care is essential for optimizing outcomes, reducing complications, and expediting recovery.

Recent studies have highlighted the significant potential of medium-chain triglyceride (MCT) diets, owing to their unique absorption pathway and metabolic properties. MCT contains mainly medium-chain fatty acids (MCFA), which is absorbed in the intestine and transported to the liver via the portal system instead of the lymphatic system. This helps to bypass the lymphatic system, thereby reducing the volume of lymph. MCFAs also provide better energy utilization in stressed condition since it does not require carnitine shuttle upon metabolism, which is beneficial to post-operation recovery.

Several studies have demonstrated the benefits of MCT diets in managing chyle leaks and supporting gastrointestinal recovery, particularly in conditions that strain the lymphatic system. For instance, short-term MCT-enriched diets have been associated with improved post-operation recovery of gastrointestinal, hepatic and renal functions, reduced total chest drainage volumes, and shorter hospital stay when compared to regular diet groups.

Patients with post-operative chyle leak following thoracic surgery are often given an MCT diet to reduce chest drain volume and hence shorten hospital stay. Based on the successful use of MCT diet on patients with chyle leak after lobectomy, it is hypothesized that patients with chylothorax provided with post-operative MCT diet can also shorten hospital stay by decreasing chest drainage. Therefore, a prospective and randomized trial is designed to investigate how post-operative MCT diet in lung resection patients without chylothorax may affect hospital stay and post-operative recovery.

This study is a single-center, prospective, randomized trial designed to investigate how a post-operative diet enriched with MCT affects recovery in patients undergoing video-assisted thoracic surgery (VATS). Medical students from the Chinese University of Hong Kong, under the supervision of the principal investigator, will conduct the study, including obtaining consent and collecting data. Experienced surgeons at the Prince of Wales Hospital will perform the VATS procedures.

2.2 Hypotheses

1. MCT diet can speed up post-operative recovery and shorten hospital length of stay.
2. MCT diet poses no adverse effects in post-operative recovery for patients without chyle leak following lung surgery.
3. The use of MCT diet after discharge for 2 weeks can enhance patient recovery and possibly reduce readmissions or complications.

Inclusion Criteria:

General Inclusion Criteria for All procedures:

1. Age between 18 - 80 years
2. Body mass index <35 kg/m2
3. Suitable for minimally invasive surgery
4. Willingness to participate as demonstrated by giving informed consent

Project-specific Criteria:

1. Patients performed lobectomy with lymph node dissection

Exclusion Criteria:

Patient general exclusion criteria:

1. Contraindication to general anesthesia
2. Severe concomitant illness that drastically shortens life expectancy or increases the risk of therapeutic intervention
3. Untreated active infection
4. Non-correctable coagulopathy
5. Emergency surgery
6. Vulnerable population (e.g. mentally disabled, pregnancy)

Project-specific Criteria

1. Segmentectomy
2. Pleurodesis
3. Esophageal procedures
4. Redo/readmitted patients for lung resection
5. Chylothorax (Triglyceride > 110 mL, excluded at day 1 routine lab check)
6. Air leak (> 30 mL/min when back to ward)
7. Heart Failure
8. Renal failure (estimated GFR < 30; CKD grading stage 4-5)
9. Moderate to severe adhesion (defined at randomization by surgeon; criteria include estimated surface area of adhesion and staging)
10. History of tuberculosis or empyema