Continuous positive pressure ventilation during epidural blockade – effects on cardiac output distribution

Abstract

The locally mediated nutritive vasoregulation of vital organs outweighed the sympathetic blockade induced by epidural blockade. During Thep blockade the animals were less capable of responding to the haemodynamic changes induced by CPPV8, probably due to the blockade of the cardiac part of the sympathetic nervous system.

Effects of thoracic epidural anaesthesia on microvascular gastric mucosal oxygenation in physiological and compromised circulatory conditions in dogs †

“…PEEP in particular, as applied in our model of circulatory impairment, activates the sympathetic nervous system. 23 By inference, extended sympatholysis produced by TEA should prevent splanchnic vasoconstriction, leading to preserved splanchnic tissue perfusion and oxygenation. However, our results suggest the opposite, that TEA worsened the impairment of mucosal oxygenation.…”

“…Several mechanisms may contribute: TEA did not selectively aggravate the impairment of regional oxygenation (mHbO 2 ) produced by PEEP, but concomitantly also worsened the depression of systemic haemodynamics and DO 2 , the latter finding also being supported by others. 23 Thus, changes in mHbO 2 may primarily reflect a depression of systemic oxygen-transport, which in turn may result from decreased cardiac sympathetic drive, and reduced capacitance vessel tone (attenuating cardiac preload via venous blood pooling) and blunted adrenoceptor-mediated renin-angiotensin release. 23 This concept of systemic-to-regional dependency during TEA is further supported by our findings that fluid resuscitation alone, directed to restore CO during impaired cardiocirculatory conditions, was sufficient to also completely restore regional mHbO 2 , and that the correlation between mHbO 2 and DO 2 was not altered by TEA.…”

Ropivacaine May Have Advantages Compared to Bupivacaine in Porcine Endotoxemic Shock

“…Both ropivacaine and bupivacaine are absorbed rapidly from the epidural space into the circulation, although their kinetics vary (19,20). It should also be remembered that epidural administration of local anaesthetics, but not saline, cause profound effects on hemodynamics (21). In these circumstances, we decided to administer our drugs iv in order not to interfere pharmacological effects with circulatory changes caused by epidurally administered local anaesthetics.…”