Background: Analgesics are commonly used to provide pain relief after surgery. These drugs produce some extended depression of immunity. A prospective randomized controlled trial was designed to observe expressions of T-lymphocyte subsets (CD3(+), CD3(+)CD4(+) and CD3(+)CD8(+)), natural-killer cells (CD3(-)CD16(+)CD56(+)), and activated T-lymphocytes (CD3(+)CD25(+)) of patients undergoing gastric cancer surgeries and receiving patient-controlled intravenous analgesia (PCIA).

Methods: Forty-five patients undergoing elective gastric cancer surgeries under general anesthesia were randomly allocated into 3 groups. Group I received PCIA using morphine after surgery, group II using tramadol, and group III using tramadol with lornoxicam. The analgesic efficacy was evaluated by visual analog scale (VAS) and Bruggrmann comfort scale (BCS). Expressions of CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), CD3(-)CD16(+)CD56(+), and CD3(+)CD25(+) were measured as percentages of total lymphocytes by flow cytometer at 5 time points.

Results: There was no significant difference in analgesic efficacy and the baselines of CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), CD3(-)CD16(+)CD56(+), and CD3(+)CD25(+) in all groups. Compared with the baseline, CD3(+)CD8(+) had no changes in all groups at any time point. Ninety minutes after incision, CD3(+), CD3(+)CD4(+), CD3(-)CD16(+)CD56(+), and CD3(+)CD25(+) were lower in all groups (P<0.05). 24 h after surgery, CD3(+), CD3(+)CD4(+), CD3(-)CD16(+)CD56(+), and CD3(+)CD25(+) were lower in group I and group II (P<0.05); meanwhile CD3(+), CD3(+)CD4(+), and CD3(+)CD25(+) returned to the baseline but CD3(-)CD16(+)CD56(+) was still low (P<0.05) in group III. 48 h after surgery, CD3(+), CD3(+)CD4(+), CD3(-)CD16(+)CD56(+), and CD3(+)CD25(+) returned to the baseline in group II and group III, but not in group I (P<0.05). 72 h after surgery, CD3(+), CD3(+)CD4(+), CD3(+)CD4(+)/CD3(+)CD8(+) returned to the baseline, but CD3(+)CD25(+) and CD3(-)CD16(+)CD56(+) were still low in group I (P<0.05).

Conclusion: PCIA using lornoxicam with tramadol has the same good analgesic efficacy and less immunity depression than PCIA using morphine or tramadol.