Safety of nerve conduction studies in patients with peripheral intravenous lines

Nerve conduction studies (NCS) may be deferred because of a perceived risk of cardiac arrhythmia in the presence of same-limb peripheral intravenous lines. Patients with implanted pacemakers or defibrillators provide a model in whom this risk can be assessed. Twenty patients, seven with pacemakers and 13 with defibrillators, had peripheral intravenous lines placed during routine care and underwent NCS in the same limb. NCS were performed with the intravenous line clamped and then with saline open to gravity. The implanted cardiac device was interrogated before and after the study. During NCS the surface electrocardiogram and intracardiac electrograms were monitored continuously. Electrical impulses generated during routine NCS were never detected by the sensing amplifiers of the pacemakers/defibrillators and did not affect the programmed settings or interfere with pacing of the device. Routine NCS are safe in patients with same-limb peripheral intravenous lines, even with saline open to gravity.