Sympathetic blockade during extradural analgesia with mepivacaine or bupivacaine

Abstract

The extent of sympathetic blockade in 36 patients, who had been given extradural analgesia, was studied by means of the skin conductance response (SCR). The SCR was also studied in six healthy volunteers who received, in a cross-over fashion, infusions of physiological saline (placebo) and saline containing mepivacaine. Two more volunteers were given saline containing bupivacaine. Extradural analgesia caused a partial blockade of sympathetic activity. The higher the level of analgesia the greater the degree of inhibition of the SCR. Complete blockade of the SCR or only a weak response in the foot was obtained in the majority of cases when the level of analgesia reached a dermatome level of T4 or higher. There was no significant relationship between the degree of motor blockade of the lower extremities and the intensity of blockade of the SCR. Extradural injection of 2% mepivacaine had a greater effect on the SCR than did 0.5% bupivacaine. There was no indication that infusion of mepivacaine or bupivacaine in volunteers, whose blood levels were as high as or higher than those likely to be produced during extradural analgesia, affected the SCR.

Effects of epidural anaesthesia on intestinal oxygenation in pigs †

“…Frequently this procedure is associated with a marked decrease in mean arterial perfusion pressure. 15 The mechanisms of this decrease in mean arterial pressure are increased splanchnic venous capacitance as a result of markedly decreased splanchnic nerve sympathetic activity, and relaxation of precapillary arterioles and sphincters. 16 Few data exist regarding the effects on intestinal blood ow and mucosal oxygenation resulting from the decrease in mean arterial pressure induced by epidural anaesthesia.…”

Effects of epidural anesthesia on sympathetic nerve discharge to the skin

“…Based on studies of peripheral blood flow and central hemodynamics, Bromage suggested epidural anesthesia to be associated with merely a reduction in sympathetic neural traffic rather than a complete blockade (5). This notion was supported in a recent study by Malmqvist et al (9), who found that despite high levels of epidural blockade (above T5), weak galvanic skin responses to arousal could still be elicited in the foot in some patients, indicating an incomplete sympathetic blockade. In a receiit study (10) using direct intraneural recordings, we found that epidural mepivacaine anesthesia with a sensory block at T10 or above abolished sympathetic nerve activity to muscles recorded in the peroneal nerve, arguing against the notion of only a partial sympathetic blockade following epidural anesthesia.…”

A comparison of the effects on postoperative pain relief of epidural analgesia started before or after surgery

“…However, mepivacaine 2% has been shown to be more ef®cient than bupivacaine 0.5% in attenuating neural function during epidural anaesthesia [18]. In contrast to Dahl and colleagues, who used bupivacaine 0.75%, we utilized mepivacaine 2% for perioperative epidural analgesia.…”

“…In contrast to Dahl and colleagues, who used bupivacaine 0.75%, we utilized mepivacaine 2% for perioperative epidural analgesia. However, mepivacaine 2% has been shown to be more efficient than bupivacaine 0.5% in attenuating neural function during epidural anaesthesia [18]. A complete afferent neural blockade is not obtained with epidurally administered bupivacaine, despite analgesia to pin‐prick, when evaluated with somatosensory evoked potentials [19].…”