Sir, The use of peripheral nerve stimulation (PNS) enhances the safety and accuracy of regional blocks by preventing needle-nerve contact.1 A PNS needle delivers electrical pulses to locate and target a peripheral nerve. However, it is an expensive medical modality, which precludes its benefit of safe regional anesthesia in middle- and low-income countries. Like commercially available PNS needles, a peripheral IV catheter needle is externally covered with an insulating cannula, except at the tip, which makes it an ideal candidate for conversion into an improvised PNS needle. Various authors have devised different mechanisms to conduct electric pulses through the peripheral IV cannula needle as an improvised PNS needle. Kothari et al.2 devised an indigenous version of an insulating needle using two peripheral IV cannulas. The Teflon sheath of a 20G cannula was inserted over an 18G needle, and a crocodile clamp (PNS cathode) was attached to the exposed metallic section of the 18G needle; however, the issue of needle sterility after improvization is a concern.3 Jain et al.4 improvised the PNS needle to require an IV cannula and a 14G hypodermic needle. They proposed perforating the diaphragm of the flashback chamber with a 14G needle; thereafter, the PNS cathode was inserted through the perforated flashback chamber and adjusted to contact the cannula needle. Once the nerve is localized, the metallic stylet is removed, leaving the catheter in situ for drug injection. The issue of sterility and the inability to elicit motor responses after style removal are the primary concerns.3 Vithal et al.5 proposed a nerve stimulator assembly with an IV cannula, spinal needle, and 10 cm extension tubing. To make an electric connection with the cannula needle, they introduced the spinal needle through the injection port of the IV cannula, and the other end of the spinal needle was connected to the PNS cathode. Their improvization does not require the needle to be removed before drug administration and was not associated with sterility issues.3 We have proposed an innovative “pin connector wire” (PNS lead wire assembly), which rather than making any changes in the peripheral IV cannula, simply plugs and is inserted over the injection port, and the connector pin makes a mechanical connection with the IV catheter needle for conduction of electricity. The other end of the pin connector wire was connected to the monopolar socket of the PNS cathode. The pin connector wire allows simultaneous administration of the drug through the inner luminal surface, and electric pulses are conducted through the contact of the connector pin on the outer surface of the needle, thus maintaining sterility by separating the drug and electricity contact. The connector pin allows a hassle-free, user-friendly, sterile connection without any on-site manipulation of the peripheral IV cannula6 Figure 1.Figure 1: Schematic diagram of pin connector wire connection with PNS and peripheral IV catheterSafety is of utmost importance while considering affordability, and we perceive that our assembly using a cheaper pin connector wire and IV catheter is an affordable and practical solution that can potentially improve the safety of currently used indigenous PNS needles. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Singh et al. (Wed,) studied this question.