| Abstract |
Aim of the study: The aim of this blind, prospective, placebo controlled study was to investigate the circulatory effects of somatostatin (SMS) and it's derivative sandostatin (SDS) on cancer patients during the early postoperative period. Using similar protocol, the study also included the hemodynamic changes during the intraoperative period as well as the possible alterations that could evolve after clonidine pretreatment. Methods: The protocol included the following: ¨ Intraoperative period: · During anesthesia with propofol and sufentanil one group of patients received a bolus dose of SMS 3.5 μg/kg followed by an infusion of SMS at 3.5 μg/kg/min. The second group of patients, received a bolus dose of SDS 3 μg/kg, followed by an infusion of normal saline and the third group received a 20 ml bolus dose and a consecutive infusion of normal saline. (Studies 1 & 2) · Another group of patients received SDS during anaesthesia in order to investigate possible effects on Heart Rate Variability (Study 3) ¨ Postoperative period: · During the early postoperative period, another group of patients received randomly a similar scheme of drugs that consisted of the consecutive (with appropriate breaks in - between) administration of SMS, SDS or normal saline according to the following: rank: either normal saline - SMS - SDS or SMS - normal saline - SDS at doses similar to the previous studies 1 and 2 (Studies 4 & 5). · The same consecutive scheme of studies 4 and 5 was also administered to patients during the early postoperative period in order to evaluate it's effect on electrocardiographic recordings and on acid base status and blood gas analysis (Studies 6 & 7) · Finally, three more groups of patients received the scheme of studies 1 & 2 during the early postoperative period that was preceded by clonidine pretreatment. (Study 8) The following parameters were monitored during all studies: arterial blood pressure, heart rate, central venous pressure and when applicable: pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, indices of oxygen transport and utilization, lead II recordings of the electrocardiogram and heart rate variability (HRV). Results: One hundred and eleven (111) patients were studied. Forty two of them received SMS, 32 patients received SDS, 20 patients received both agents and 11 received only normal saline. Immediately after the administration of SMS or SDS a slowing of heart rate was noticed, that was both clinically and statistically significant, and which was followed by an increase of arterial blood pressure, pulmonary artery pressure and the central venous pressure. Cardiac output, pulmonary capillary wedge pressure, indices of oxygen transport and utilization, HRV, acid base balance and blood gases did not presend any significant changes. There were not detected any changes of the QRS complex of the ECG. However there were a few arrhythmias detected, which were mainly bradyarrhythmias of very short duration. Of the groups of patients that were pretreated with clonidine, we observed similar hemodynamic changes though of diminished power. Conclusion: The hemodynamic effects of the peptides Somatostatin and Sandostatin are manifested with a vasopressor effect on the systemic and pulmonary circulation during anaesthesia and the postoperative period, without modulating the sympathetic discharge of autonomic nervous system to the cardiovascular system. These effects can be diminished but not abolished by clonidine pretreatment and are most probably produced by a direct action on the physical receptors of somatostatin, located on the myocardium and the peripheral vessels. The administration of SMS and SDS at doses used in this study, proved to be safe when administered to cancer patients.
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