Acute Cigarette Smoking Reduces Vasodilative Effect Induced by Sympathetic Block in Dogs:

Comparison of 2% mepivacaine, clipping, and radiofrequency thermocoagulation for duration and magnitude of action in peripheral arterial blood flow induced by sympathetic block in anesthetized dogs

BACKGROUND AND OBJECTIVES

Thoracic sympathetic block has recently been performed by placement of the clips on the sympathetic chain to interrupt nerve conduction. The aim of this study was to compare clipping with 2% mepivacaine and radiofrequency thermocoagulation for the potency of sympathetic block from the results of the duration and magnitude of the vasodilation effect induced by thoracic sympathetic block in dogs.

METHODS

We measured mean arterial pressure, heart rate, and right and left brachial artery blood flow (BABF) before and after thoracic sympathetic block in 24 dogs. The experimental protocol was designed as follows: (1) left thoracic sympathetic block by 1.0 mL of 2% mepivacaine (n = 8), (2) left thoracic sympathetic block by clipping (n = 8), and (3) left thoracic sympathetic block by radiofrequency thermocoagulation (n = 8).

RESULTS

Mean arterial pressure and heart rate did not change significantly throughout the study in either group. Left thoracic sympathetic block by 2% mepivacaine increased left BABF significantly from 5 to 70 mins after the block (baseline, 100%; peak at 10 mins after the block, 179% ± 33%; P < 0.01). Left thoracic sympathetic block by clipping increased left BABF significantly from 5 to 120 mins after the block (baseline, 100%; peak at 30 mins after the block, 156% ± 31%; P < 0.01). Left thoracic sympathetic block by radiofrequency thermocoagulation increased left BABF significantly from 5 to 120 mins after the block (baseline, 100%; peak at 10 mins after the block, 206% ± 31%; P < 0.01).

CONCLUSIONS

Clipping may have a same potency compared with 2% mepivacaine and a less potency compared with radiofrequency thermocoagulation in thoracic sympathetic block in dogs.

Comparison of bupivacaine, ropivacaine, and levobupivacaine in an equal dose and concentration for sympathetic block in dogs

BACKGROUND AND OBJECTIVES

The aim of this study was to compare the potency of bupivacaine, ropivacaine, and levobupivacaine in an equal dose and concentration for sympathetic block.

METHODS

We measured mean arterial pressure, heart rate (HR), and right and left brachial artery blood flow (BABF) before and after cervicothoracic sympathetic block in 24 dogs. The experimental protocol was designed as follows: (1) left cervicothoracic sympathetic block with 1.0 mL of 0.25% bupivacaine (n = 8), (2) left cervicothoracic sympathetic block with 1.0 mL of 0.25% ropivacaine (n = 8), and (3) left cervicothoracic sympathetic block with 1.0 mL of 0.25% levobupivacaine (n = 8).

RESULTS

Mean arterial pressure and heart rate did not change significantly throughout the study in either group. Left cervicothoracic sympathetic block with 0.25% bupivacaine increased left BABF significantly from 5 to 100 mins after the block (baseline, 100%; peak at 20 mins after the block, 218% +/- 48%; P < 0.01). Left cervicothoracic sympathetic block with 0.25% ropivacaine increased left BABF significantly from 5 to 100 mins after the block (baseline, 100%; peak at 10 mins after the block, 254 +/- 38%; P < 0.01). Left cervicothoracic sympathetic block with 0.25% levobupivacaine increased left BABF significantly from 5 to 80 mins after the block (baseline, 100%; peak at 20 mins after the block, 183% +/- 38%; P < 0.01).

CONCLUSIONS

Ropivacaine may induce a greater increase in vasodilation than bupivacaine and levobupivacaine at the same dose and concentration for sympathetic block in dogs.