Journal of anesthesia
-
Journal of anesthesia · Dec 1995
Effects of stellate ganglion block on cardiac coronary circulation.
Since the stellate ganglion contains cardiac sympathetic nerves, stellate ganglion block (SGB) may influence cardiac and coronary hemodynamics. We investigated this influence of SGB by measuring the heart rate (HR), the left circumflex coronary artery blood flow (CBF), the maximum rate of increase of the left ventricular pressure (LV max dP/dt), the cardiac output (CO), the myocardial oxygen consumption (MVO2), and the myocardial oxygen extraction ratio (MOER) in nine dogs before and after performing SGB by means of injection of 2 ml 1% mepivacaine. Left SGB resulted in a decrease of 10% in CBF and a decrease of 15% in LV max dP/dt, but HR, CO, and MVO2 remained unchanged. ⋯ Inhalation of 100% oxygen decreased MOER to the pre-SGB level in either side, thus improving the myocardial oxygen supply-demand relationship. This study suggests the possibility that SGB has deteriorative effects on the myocardial oxygen supply-demand relationship. Those effects were counteracted by the inhalation of 100% oxygen.
-
Journal of anesthesia · Dec 1995
Difference of train-of-four fade induced by nondepolarizing neuromuscular blocking drugs: a theoretical consideration on the underlying mechanisms.
Nondepolarizing neuromuscular blocking drugs induce train-of-four (TOF) fade, i.e., the reduction of the fourth to the first twitch height in a train under TOF stimulation. It has been observed that the degree of TOF fade varies with the drug used and is inversely correlated with the potencies of the drug. ⋯ The model was based on the following assumptions: (1) Twitch response is evoked by the binding of acetylcholine (ACh) molecules to the postsynaptic nicotinic receptors in a neuromuscular junction, (2) time-dependent ACh mobilization in a motor nerve terminal results in less ACh output at the fourth stimulus in a train than at the first stimulus, (3) the drugs compete with ACh for the postsynaptic receptors and inhibit the receptor-binding of ACh, and (4) the drugs have various affinities for the receptors. This study suggested that the difference of affinities of the drugs for postsynaptic ACh receptors may cause the difference of TOF fade.