The effects of volume loading during epidural analgesia

We have determined the effects of volume loading on the cardiovascular changes during epidural analgesia in 37 patients, who underwent various kinds of surgery. The patients were placed in 4 groups, depending upon the level of analgesia and utilization of volume loading with colloidal solutions. If the analgesia extended above Th4 we grouped them as "high epidural" and lower than Th5 level they were grouped as "low epidural". The cardiac output was measured through a Swan-Ganz catheter with thermo-dilution methods and cardiovascular variables were calculated by standard formulas. Under epidural block the most significant changes were a fall in blood pressure with decrease in cardiac output which were more pronounced during high epidural analgesia. Volume loading during the induction period with colloidal solutions would prevent the marked fall of blood pressure in half of cases studied, but in the other half the infusion was not effective for the prevention of fall in blood pressure. On every occasion over-loading effects on the right side of the heart were observed with the infusion of colloidal solutions. Also, a marked fall in systemic vascular resistance was observed with the infusion. In consequence the volume loading did not prevent the fall in arterial pressure. To manage the latter which was observed during epidural block, some sympathomimetic agents would be necessary with the volume loading. This approach would be much more important in patients with dehydration and high level of epidural analgesia.