A patient using a TENS unit for chronic back pain finds it ineffective. What should the PT advise?

When a patient finds a TENS unit ineffective for managing chronic back pain, switching to modulation-mode TENS is a prudent option. Modulation-mode TENS varies the pulse frequency, pulse duration, or both, throughout the treatment session. This variability can help prevent the adaptation of the nervous system to a constant stimulus, which may contribute to the perception of ineffectiveness over time. By providing varying stimulation patterns, modulation-mode TENS can potentially enhance analgesia and improve the overall efficacy of the treatment for pain relief.

The other options may not address the issue of ineffectiveness as directly. For instance, switching to low rate TENS or increasing treatment frequency could both potentially change the results; however, low rate TENS typically targets a different mechanism that may not directly solve the problem of inadequate pain relief. Adjusting pulse duration may also alter the sensation but does not offer the same variability and can limit the effectiveness as well. Hence, modulation-mode TENS stands out as a more comprehensive approach to enhance patient comfort and pain management.