Cardiovascular effects of dihydroergotamine during epidural anaesthesia in dogs

The haemodynamic changes during epidural anaesthesia and following the administration of dihydroergotamine (DHE; 10 micrograms/kg i.v.) were studied in 7 dogs (epidural group). Epidural anaesthesia was associated with reductions in mean arterial, mean pulmonary arterial and mean right atrial pressures. Femoral flow was increased by 119.9 +/- 35.0% and femoral resistance fell by 62.7 +/- 7.2%. All these changes were abolished by additional administration of DHE during epidural anaesthesia. In a second group of dogs (control group, n = 8) with intact innervation, i.e. without epidural block, DHE (10 micrograms/kg iv.) also decreased femoral flow and increased femoral resistance which, however, was significantly less pronounced ( p less than 0.01). It is concluded that DHE in epidural anaesthesia constricts arteriolar resistance vessels, mainly within the blocked areas.