Vasoactive effects of smoking as mediated through nicotinic stimulation of sympathetic nerve fibers

Patients who smoke have higher complication rates than nonsmokers following many surgical procedures. It is not known if the adverse effects of smoking are caused by a nicotine effect or by some other potentially harmful agents that exist in tobacco smoke. It is also not known if these vasoactive effects are mediated through sympathetic nerve fibers (via nicotinic receptors in ganglia) or through elevated circulating levels of vasoactive hormones. We designed a 5-day protocol to measure relative blood flow both before and after a digital sympathetic block in the digits of subjects who were regular smokers following both smoking and wearing of a transdermal nicotine patch. Suitable pulse/wave tracings were recorded on 23 subjects. We also measured serum levels of nicotine, cotinine, vasopressin, norepinephrine, epinephrine, dopamine, and carboxyhemoglobin on each test day. Data for these serum levels were available in 30 test subjects. Digital sympathetic block had a significant beneficial effect in reversing the decreased digital blood flow that occurred after smoking (and also with use of the nicotine patch), despite the elevated circulating levels of vasopressin and norepinephrine seen with smoking. The vasoactive effects of smoking are probably due to the nicotinic effects on sympathetic fibers at the ganglionic levels.