Background: Perioperative fluid restriction can lead to better clinical outcomes and reduced complications. However, whether perioperative fluid restriction can alter the patient's postoperative cellular immunity is unknown. Therefore, a randomized, prospective clinical study was designed to determine whether fluid restriction improves immunological outcome in elderly patients who undergo gastrointestinal surgery for cancer removal.
Methods: A total of 179 patients aged 65 years or older were recruited for the study and were randomly assigned to receive the restricted fluid regimen (R group) or the standard fluid regimen (S group). Postoperative T-lymphocyte subpopulations (CD3(+), CD4(+), and CD8(+)) frequencies and monocyte HLA-DR expression was investigated. Perioperative complications and cellular immunity changes were analyzed comparatively between the two groups.
Results: The restricted intravenous fluid regimen was associated with significantly less postoperative complications (1.5 complications/patient vs. S group: 2.2 complications/patient), especially for infection complications (15% vs. S group: 27%, p = 0.04). Circulating CD3(+) T-cells were suppressed after surgery in both treatment groups, but the cell frequency (cell/μL) was higher in the R group (746 vs. S group: 480 at postoperative day (POD) 2, p = 0.022; 878 vs. 502 at POD 3, p = 0.005; 892 vs. 674 at POD 5, p = 0.042). Similarly, the HLA-DR expression (% of all T cells) in monocytes were decreased in both groups, but the expression remained higher in the R group (66.20 vs. S group: 51.97 at POD 1, p = 0.029; 68.19 vs. 51.26 at POD 2, p = 0.039; 72.19 vs. 57.45 at POD 3, p = 0.014; 73.92 vs. 60.46 at POD 5, p = 0.036). Multivariate analysis suggested that perioperative CD3(+) T cell changes were associated with the development of postoperative complications [odds ratio (OR) = 1.963; 95% confidence interval (CI) 1.019-3.782; p = 0.044] and postoperative infections (OR = 3.106; 95% CI 1.302-7.406; p = 0.011).
Conclusions: In elderly gastrointestinal cancer patients, cellular immunity is better preserved by the perioperative fluid restriction regimen. The better preserved cellular immunological function is correlated with a reduced perioperative complications rate.