Predictive value of interleukin 6 (IL-6) and gastric intramucosal pH (pH-i) levels in splanchnic ischemia during major abdominal surgery

Introduction

Abdominal surgery activates monocytes, macrophages and endothelial cells resulting in elevated blood levels of different interleukins, which are directly correlated to the entity of surgical stress [1]. The present study investigates the effects of splanchnic ischemia on plasma concentrations of interleukin-6 (IL-6) and the predictive power of IL-6 levels for post-surgery complications to occur.

Patients and methods

We have studied 12 patients scheduled for major abdominal surgery and informed consent was obtained from all patients. All patients were treated with H2 receptor antagonists before surgery. Gastric intramucosal pH (pH-i) measurements and arterial blood probes for IL-6 dosage were realised after standard anaesthesia induction and prior to the start of surgical procedure (TI), every 60 min after Tl during surgery (Tla, b, etc), immediately after extubation (T2), and after 1 h (T3), 2 h (T4), 24 h (T5) and 48 h (T6) after T2. Patients with and without complications during and after surgery were identified and mean values and standard deviation of IL-6 and pH-i for this two patient groups were calculated and plotted on a Cartesian diagram with cut-off points of 7.32 for pH-i and of 300 pg/ml for IL-6. Mean values of pH-i and IL-6 were evaluated with the Mann-Whitney test, P values < 0.05 were considered as significant.

Results

Patient with complications demonstrated significantly lower values of pHi (7.19 ± 0.113 versus 7.39 ± 0.096) and significantly higher values of IL-6 (596.7 ± 687 versus 65 ± 43.5) during surgical intervention compared to patients without complications.

Five out of seven plotted values of patients with complications during or after surgery are located in the lower right quadrant of the diagram (pH-i < 7.32, IL-6 > 300 pg/ml) and eight out of nine plotted values of patients without complications are located in the upper left quadrant of the diagram (pH-i > 7.32, IL-6 < 300 pg/ml). The differences between the two groups are statistically significant (P = 0.0029).

Conclusion

Our results suggest that splanchnic ischemia during major abdominal surgery, measured by pH-i, is associated to increased levels of IL-6. Those patients with higher IL-6 levels during and immediately after major abdominal surgery seem to have a higher probability to develop complications.