Laboratory and Clinical Investigation into Lower Limb Ischaemic Pain, and the Effect of Transcutaneous Electrical Nerve Stimulation (Tens) on Measures of Pain and Walking Performance
Seenan, C. (2013) Laboratory and Clinical Investigation into Lower Limb Ischaemic Pain, and the Effect of Transcutaneous Electrical Nerve Stimulation (Tens) on Measures of Pain and Walking Performance, no. 457.
Aims: The aims of this programme of research are to investigate the subjective description of ischaemic pain and to investigate the effects of TENS on lower limb ischaemic pain and walking performance in patients with Intermittent Claudication (IC). Methods: Four studies were conducted: two in the laboratory and two clinical trials. Laboratory- The first study investigated the reliability of a method of inducing lower limb ischaemic pain in healthy volunteers, the modified Submaximal Effort Tourniquet Test (mSETT). The second investigated the effects of High Frequency TENS (HF-TENS) and Placebo TENS (P-TENS) on lower limb ischaemic pain induced using the mSETT in healthy volunteers. Clinical- The first clinical study investigated the effects of HF-TENS and Low Frequency TENS (LF-TENS) on measures of pain and treadmill walking performance in patients with Peripheral Arterial Disease (PAD) and IC. The second examined patients' experiences of using TENS at home for PAD and IC. Results: The mSETT was found to have good test-retest reliability and induce pain similar in quality to that experienced by patients with IC. The pain experience induced with the mSETT was reduced by both HF- and P-TENS compared to baseline. HF-TENS however was more effective compared to P-TENS in this regard, prolonging time to pain threshold and tolerance whilst reducing the levels of pain reported throughout. In patients with PAD and IC, HF and LF-TENS interventions were found to increase maximum walking distance on a treadmill compared to P-TENS. HF-TENS was also found to increase pain-free walking distance. The experience of using TENS in daily life was characterised by feelings of both benefit and disappointment. This was interpreted through the following themes: (i) 'masking, but not taking the pain away' and (ii) 'walking further, but not far enough'. Conclusions: The mSETT is a reliable method of inducing lower limb, ischaemic pain in healthy volunteers and could be useful for the purposes of pre-clinical analgesic trials and investigation of the ischaemic pain experience. HF-TENS was found to reduce mSETT pain indicating hypoalgesic effects of TENS in experimentally induced, lower limb ischaemic pain. HF and LF-TENS have potential as interventions that increase walking performance for patients with IC. If using TENS at home for IC, expectations of treatment effect need to be managed to avoid disappointment and feelings of frustration.