Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Epidural sufentanil and bupivacaine for labor analgesia and Doppler velocimetry of the umbilical and uterine arteries.
The pain of parturition is associated with major physiologic alterations mediated by neurohumoral factors and increased activation of the sympathetic nervous system. Epidural local anesthetics abolish or alleviate many of the pain-mediated responses by reducing maternal catecholamine levels, inducing sympathectomy and consequent vasodilatation. The hormone response to surgical stress is not attenuated after epidural opioids as efficiently as after local anesthetics. Opioid receptors may modulate sympathetic outflow at a spinal level. This study was performed to compare the effects of epidural sufentanil and bupivacaine on the uterine and placental circulation. ⋯ Epidural sufentanil and bupivacaine provide effective analgesia with acceptable side effects during the first stage of labor in healthy parturients. Neither drug had any detrimental effects on blood flow indexes reflecting peripheral vascular resistance in the umbilical and uterine arteries in healthy parturients.
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Intraspinal clonidine injection produces analgesia free of respiratory depression, but also decreases blood pressure and causes sedation. Spinal neostigmine injection alone increases blood pressure in animals and enhances clonidine-induced analgesia. ⋯ These data are consistent with neostigmine's counteraction of clonidine-induced hypotension by a spinal muscarinic mechanism and support investigation of spinal alpha 2-adrenergic-cholinergic combinations for pain therapy.
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Spinal cord perfusion pressure may be reduced when sodium nitroprusside is used to control proximal aortic hypertension during thoracic aortic clamping. The effect of esmolol infusion on spinal cord perfusion pressure during thoracic aortic clamping is unknown. This study compares spinal cord perfusion pressure following control of proximal hypertension with either sodium nitroprusside or esmolol during thoracic aortic clamping. ⋯ Esmolol was associated with greater spinal cord perfusion pressure, but adverse hemodynamic effects, when compared with nitroprusside during thoracic aortic cross-clamping. When only surviving dogs (4 control, 5 esmolol, 6 nitroprusside) are considered, the incidence of neurologic deficit was greater in nitroprusside-treated dogs than in either control or esmolol-treated dogs. No difference in outcome was present when all dogs are considered.