The effect of sodium nitroprusside (SNP)‎ as a hypotensive agent on cytokine release and hormonal response during major pelvic surgery

الملخص EN

Background : the release of a variety of inflammatory mediators (cytokines) during surgery attempts to limit injury and spread of infection.

Variation in anesthetic technique may influence this cytokine balance and has important beneficial effects in promoting acute phase response and protection against viral and bacterial infection.

Aim of the work : this study was done to evaluate the effect of induced hypotension, using Sodium Nitroprusside (SNP), on proinflammatory cytokines (IL-6, IL-1β and TNF-∝) and hormonal response (cortisol, growth hormone and insulin) during major pelvic operations.

Patients and methods : this study was conducted on 40 patients scheduled for either radical cystectomy or anterior pelvic excentration at the National Cancer Institute, Cairo University.

They were randomly allocated to two groups: the control group, included 20 patients, where in-tra-operative mean arterial pressure (MAP) was maintained above 80 mmHg.

The SNP group included 20 patients, where the MAP was maintained at 55-60 mmHg by an infusion of SNP.

In both groups, premedication was the same, anaesthesia was induced with Na Thiopentone 5-7 mg.kg-1 and pipecuronium 0.04 mg.kg-1 and maintainence with 0.8% isoflurane and 50 % nitrous oxide in oxygen.

Blood samples were obtained at four time points, namely T1 in the morning before the operation, T2 : two hours after the induction of anaesthesia, T3 : two hours after the end of surgery, and T4: 24 hours from T1.

Proinflammatory cyto-kines (IL-6, IL-1β and TNF-∝) and serum hormonal response (cortisol, growth hormone and insulin) were measured from each sample.

Results : the results of the present study demonstrated that all measured proinflammatory cytokines increased significantly 24 hours after surgery in both the study and control groups.

The levels of the cytokines were significantly higher in SNP group.

Serum cortisol concentrations increased in both groups, but reached higher level in SNP group at T2 and T3 compared to the control group.

While growth hormone levels were higher in the control group at T4.

Serum insulin level decreased significantly during sur-gery without marked differences between both groups observed at T2 and T3.

Conclusion : the present study offers evidence that induced hypotensive anaesthesia, using SNP infusion, exerted a stimulating effect on cytokine response to surgery.

The used anaesthetic technique may have clinical implication in modifying the catabolic hormonal response to radical pelvic operations.