[Physiology and pathophysiology of subarachnoid and epidural block (author's transl)]

The most important patho-physiological changes following subdural or epidural blockade are seen in the central nervous system and cardiovascular system. Preganglionic sympathetic blockade is the main reason for these changes. Sympathetic blockade is followed by a decrease in peripheral vascular resistence and alterations in the arterial and venous circulation. Hypotension occurs frequently and is thus of great interest in clinical anaesthesia. Differences in the degree of nerve block are not only seen when comparing spinal and peridural blockade but also relate to the different pharmacodynamic properties of local anaesthetics. These pharmacodynamic differences are very pronounced when the new long acting local anaesthetics bupivacaine and etiodocaine are compared in respect of motor and sympathetic denervation. All severe patho-physiological changes following subdural and peridural blockade are predictable and can be avoided by proper prophylactic treatment.