Deep tissue near infrared second derivative spectrophotometry for the assessment of claudication in peripheral arterial disease

AIM: The purpose of this study was the application of a second derivative near infrared spectrophotometric (NIRS) technique to the human calf muscle in order to see if peripheral arterial disease (PAD) patients can be discriminated from control subjects, before, during and after a standard treadmill exercise test. METHODS: Three groups of human subjects were studied: group A consisted of 10 control subjects and groups B and C were formed by PAD patients classified as Fontaine's stage 2a (5 patients) and 2b (10 patients), respectively. The measurement protocol for all groups was 9.75 minutes of standing up (phase 1), 1 minute of exercise (phase 2) and 1 minute of rest (phase 3). Seven variables were defined at different times from the onset of the measurement protocol. RESULTS: All variables were significantly higher (p < 0.05) in group A in comparison to groups B and C. The level of significance was ten times higher (p < 0.005) at the onset (15 seconds) of the experiment and during phases 2 and 3. However, none of the variables in group B was significantly different from those in group C. CONCLUSIONS: It is shown for the first time that a second derivative NIRS technique can discriminate (p = 0.003) healthy subjects from PAD patients, in just 15 seconds of standing, with no exercise requirement. More experiments are required in order to uncover the full potential of the technique in the diagnosis of the PAD.