Surfactant Protein-D: A sensitive predictor for efficiency of preoperative pulmonary rehabilitation

Surfactant Protein D (SP-D) as a lung-derived biomarker for inflammatory lung disease is being studied in depth. Meanwhile, the Pre-operative Rehabilitation Program (PRP) has been proposed as an effective treatment to reduce the incidence of Post-operative Pulmonary Complications (PPCs) and further improve quality of life. However, the relationship between serum SP-D levels and PRP remains unclear. This study aimed to explore the correlation between these two phenomena and validate the feasibility of using preoperative serum SP-D levels to predict or assess the effectiveness of PRP.

A prospective study with a total of 80 lung cancer patients with risk factors for PPCs was conducted; subjects were randomly divided into an Intervention Group (IG, n = 36) and a Control Group (CG, n = 44). The IG was treated with one week of PRP, and the CG was treated for the same duration with routine preoperative preparation before the lobectomy. Peripheral venous blood samples were collected at five time points and serum SP-D levels were measured by enzyme-linked immunosorbent assay (ELISA). We analysed the serum level changes of SP-D as well as the PPCs occurred between the two groups.

Both groups were comparable at baseline. The average levels of SP-D in both groups showed a decline trend with time, and levels before the day of surgery revealed a significant decline range in the IG compared with the CG (6.56 ± 5.30 vs. 1.05 ± 2.79 ng/ml, P < 0.001). The incidence of PPCs in the IG was significantly lower than in the CG (2/36 vs. 10/44, p = 0.032), as were the PPC person-times occurring from postoperative days 1-4 (POD 1-4) (5/36 vs. 15/44, p = 0.038) and the total person-times (5/36 vs. 19/44, p = 0.004). The overall SP-D levels on the day before surgery in patients with PPCs were significantly higher than those without PPCs (34.07 ± 4.32 vs. 30.30 ± 6.52 ng/ml, p = 0.005); furthermore, the overall SP-D levels on admission day in CG patients with PPCs were also significantly higher than those without PPCs (34.93 ± 4.15 vs. 29.81 ± 7.47 ng/ml, p = 0.045).

The Preoperative Intensity Rehabilitation Program could positively decrease the serum SP-D levels in lung cancer patients with PPC risk factors, and higher preoperative serum SP-D levels may related to a higher incidence of PPCs. Serum SP-D may be a potential predictor for evaluating the efficiency of PRPs and the risk of PPC occurrence.