BLOOD FLOW IN THE HAND AND FOREARM AFTER PARAVERTEBRAL BLOCK OF THE SYMPATHETIC GANGLIA. EVIDENCE AGAINST SYMPATHETIC VASODILATOR NERVES IN THE EXTREMITIES OF MAN

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Abstract
On two occasions, the sympathetic ganglia supplying the right upper extremity of a normal subject were injected with novocain by the paravertebral route. The blood flow in the hand and forearm was measured before, during, and after the anesthetization. Complete absence of any vasomotor activity in response to sensory stimuli or deep inspiration indicated complete paralysis of the sympathetic ganglia supplying the right hand. The sympathetic paralysis produced a striking increase in blood flow. After the effect of the novocain had passed away, the right hand was immersed in water at a temp. of 43[degree] C. Local heat produced the same increase in blood flow in the right hand as had sympathetic paralysis. The fact that acute sympathetic paralysis produces nearly maximal dilatation in the hand indicates that most of the vessels supplying the hand are under control of the sympathetic nervous system. The fact that complete blocking of sympathetic ganglia produces full vasodilatation in the hand demonstrates that inhibition of sympathetic activity is sufficient to explain the vasodilatation which occurs in the hand when the body is heated. There is no necessity for postulating that the sympathetic nerves to the hand contain vasodilator fibers. In the forearm, paravertebral noyocainization of the sympathetic ganglia caused a 6-fold increase in blood flow. A similar increase in blood flow was produced by immersing the forearm in hot water (46[degree]C.) This indicates that removal of all sympathetic impulses to the vessels of the forearm produces as great a rise in blood flow as does heating the part. Inhibition of vasoconstriction adequately explains the increase in blood flow which occurs when the body is heated, and there is no need to assume that the sympathetic nerves to the forearm contain vasodilator fibers. The fact that neither heating the forearm nor inj. of the sympathetic ganglia with novocain produces maximal dilatation in the forearm indicates that many of the vessels of the forearm are not under control of the sympathetic nervous system. It is suggested that the vessels of the skin of the forearm are under the control of the sympathetic nervous system, and that those of the muscle are not.