Case #49 When Bad Goes To Worse.
Posted 12 February 2012 - 09:33 PM
Paralytics have little to no effect on smooth muscle. Paralytics work by blocking nicotinic ACh receptors at voluntary muscle synapses, either without stimulating them (NDMB's such as roc, vec, pancuronium) or by stimulating them and then preventing them from returning to a ready state (sux). There are very few nicotinic receptors on smooth muscle (none, in fact, on most smooth muscle), so it just doesn't work. Paralyzing bronchospasm patients is also a risky proposition b/c positive pressure ventilation is very difficult in these folks and often just increases your existing air-trapping problem. The benefit of mag is that it DOES work on smooth muscle, because the relaxant effect of mag is basic to muscle physiology (it competes with calcium, and if Ca can't get into the muscle cell, it can't contract) and does not involve specific receptors.
Posted 15 February 2012 - 12:48 AM
Mag has become my "go to" agent in status asthmaticus well ahead of IV Ventolin over the last 5 years. I've found it to work wonderfully.
Posted 07 May 2012 - 12:07 PM