Peripheral Nerve Stimulator For Unassisted Nerve Blockade

Since most anesthetic practices do not have the luxury of involving an additional person in performing regional blockade, we invented a device with a foot pedal to control the current applied during the performance of the regional nerve blockade.

Background

Introduction of peripheral nerve stimulators (PNS) in the practice of regional anesthesia caused a debate as to whether there were any advantages to their use over the paresthesia technique. One obvious advantage is that PNS causes minimal discomfort to patients, since the low stimulating currents (0.1 to 2.0 mA) stimulate larger A-alpha motor fibers rather than C-pain fibers. This is in contrast to the paresthesia technique which, by its nature, causes varying degrees of discomfort. Another advantage of PNS is that patient cooperation is not needed during the procedure and the block can be performed in an anesthetized patient. The incidence of nerve damage may also be decreased compared to the paresthesia technique. The success rate with the use of PNS is equal to, or greater than, the use of paresthesia. Besides the initial cost of the stimulator and the expense for the insulated needles, a frequently cited disadvantage associated with the use of the nerve stimulator is theneed for an additional person. Because PNS usually requires frequent changes in the intensity of the stimulating current during needle advancement toward the nerve, and a sterile technique is priority for most anesthesiologists, use of PNS generally requires an extra person to manipulate the output current. While in a teaching institution this is usually not an important issue, in a busy private practice it may present a significant disadvantage, since most anesthetic practices do not have the luxury of involving an additional person in performing regional blockade. With this in mind, we invented a device with a foot pedal to control the current applied during the performance of the regional nerve blockade.

Device Description

This invention is a combination of the "Dual Stim Plus" nerve stimulator, model NS-2CA, Life-Tech, Inc., Houston Texas, and a modified "KORG" two-channel volume pedal, model KVP-001. These two devices are electronically connected and tuned to result in smooth and precise current control by pressing on the foot pedal. The new unit controls the output current in infinite number of ranges using the foot controller (i.e., 0 mA to 0.5 mA, 0 mA to 1.5 mA, etc.), allowing more precise current delivery. When connected to a standard dummy load of kiloohms, and tested on the Sony "Tektronix" 314 oscilloscope, Tektronix Inc., Beverdon, OR, characteristics of the device were essentially identical to those of the original PNS. Control of the stimulating current by the foot enables independent, one-person performance of the nerve blockade. Since the foot controller is detachable, the same unit can be used with or without its foot attachment. The invention has been approved for use on patients by our Biomedical Department at St. Luke's-Roosevelt Hospital Center (#S0012871), and has been successfully used in our clinical practice.

References

1. Peripheral Nerve Stimulation Device for Unassisted Nerve Blockade (US patent # 08/419,418).
2. Hadzic A, Vloka JD. Peripheral Nerve Stimulator for Unassisted Nerve Blockade. Anesthesiology, 1996; 84(6): 1528-1529.