Non-invasive measurement of respiratory chain dysfunction following hypothermic renal storage and transplantation

Non-invasive measurement of respiratory chain dysfunction following hypothermic renal storage and transplantation. Ischemia/reperfusion (IR) damage is a major cause of dysfunction in transplanted organs. The objective of the present study was to correlate in vivo measurements of respiratory chain (RC) function with histological and physiological parameters. Non-invasive in situ (surface fluorescence) measurements of mitochondrial NADH and near infrared spectroscopic measurements of cyt aa3 were made in unstored (Group 1) and 72 hour stored (1 to 2°C) (Group 2) autografted rabbit kidneys. The effect of sodium pentobarbitone on NADH levels was investigated. In Group 1, there was a significant change in the redox state of cyt aa3 in all (N = 6) kidneys on reperfusion which correlated with organ viability and increased NADH oxidation and minimal edema on histological examination. In Group 2 there was no significant change in cyt aa3 compared to baseline, and this correlated with poor long term organ viability, slower NADH oxidation, and severe cortical edema. Pentobarbitone inhibition of the RC resulted in rapid and complete reduction of NAD+ in Group 1, but none or only a slight reduction in Group 2. The results demonstrate that it might be possible in future to predict organ viability and histological changes by non-invasive measurements of RC dysfunction in the clinical transplant situation

A review of attenuation correction techniques for tissue fluorescence

Fluorescence intensity measurements have the potential to facilitate the diagnoses of many pathological conditions. However, accurate interpretation of the measurements is complicated by the distorting effects of tissue scattering and absorption. Consequently, different techniques have been developed to attempt to compensate for these effects. This paper reviews currently available correction techniques with emphasis on clinical application and consideration given to the intrinsic accuracy and limitations of each technique

The severity of muscle ischemia during intermittent claudication

AbstractPurpose: The degree of ischemia during intermittent claudication is difficult to quantify. We evaluated calf muscle ischemia during exercise in patients with claudication with near infrared spectroscopy. Methods: A Critikon Cerebral Redox Model 2001 (Johnson & Johnson Medical, Newport, Gwent, United Kingdom) was used to measure calf muscle deoxygenated hemoglobin (HHb), oxygenated hemoglobin (O2Hb), and total hemoglobin levels and oxygenation index (HbD; HbD = O2Hb − HHb) in 16 patients with claudication and in 14 control subjects before, during, and after walking on a treadmill for 1 minute (submaximal exercise). These measures were repeated after a second maximal exercise in patients with claudication and after 7 minutes walking in control subjects. Near-infrared spectroscopy readings during maximal exercise were then compared with a model of total ischemia induced with tourniquet in 16 young control subjects. Results: Total hemoglobin level changed little during exercise in both patients with claudication and control subjects. HHb levels rose, and O2Hb level and HbD falls were more pronounced in patients with claudication than in control subjects after submaximal and maximal exercise. During maximal exercise, HbD fell markedly by a median (interquartile range) of 210.5 μmol/cm (108.2 to 337.0 μmol/cm) in patients with claudication compared with 66.0 μmol/cm (44.0 to 101.0 μmol/cm) in elderly control subjects and 41.0 μmol/cm (36.0 to 65.0 μmol/cm) in young control subjects (P < .001). This fall also was greater than the HbD fall induced with tourniquet ischemia at 90.8 μmol/cm (57.6 to 126.2 μmol/cm; P = .006). Conclusion: Hemoglobin desaturation in exercising calf muscle is profound in patients with claudication, considerably greater even than that induced with three minutes of tourniquet occlusion. Further studies are necessary to investigate the relationship between the inflammatory response and near-infrared spectroscopy during exercise in patients with claudication. (J Vasc Surg 2002;89-93.