Effects of animal positioning on catecholamine and vasopressin levels in pigs undergoing laparoscopy.

BACKGROUND

The aim of this study was to determine the influence of different therapeutic interventions and positions on catecholamine and vasopressin levels in the pneumoperitoneum (PN) in a porcine model.

METHODS

In 43 pigs, a 14-mm-Hg PN was established and plasma concentrations of epinephrine, norepinephrine and vasopressin were measured in head-up, supine and head-down positions. Additionally, the effects of the following changes were studied: (1) increase in intrathoracic blood volume (ITBV) by means of hydroxyethyl starch infusion; (2) vasodilatation induced by sodium nitroprusside, or (3) selective sympathicolysis induced by esmolol. Again, catecholamines (ELISA) and vasopressin (RIA) were determined.

RESULTS

After PN, epinephrine levels did not significantly increase in the head-up position (p = 0.075) and remained also unchanged in the supine or head-down position. Plasma norepinephrine statistically significantly decreased in the head-up position (p = 0.046). Vasopressin concentrations remained unaltered. After increased ITBV, neither catecholamine nor vasopressin concentrations changed in any body position. Application of sodium nitroprusside or esmolol caused no changes.

CONCLUSION

Changes in endogenous catecholamine levels safely prevent cardiocirculatory instability in small pigs. Volume substitution might reduce endocrine responses to PN in the head-up position.