Direct determination of the tissue-to-blood partition coefficient for Xenon in human subcutaneous adipose tissue.

The tissue-to-blood partition coefficient for Xenon (lambda Xe) in the subcutaneous tissue in the forefoot was determined by physical and chemical analysis. The difference between patients with normal circulation (n = 10) and serve ischaemia (n = 13) was insignificant; pooled mean: 7.42 +/- 1.57 ml x g-1. The lambda Xe in the forefoot was significantly lower than lambda Xe of the abdominal wall (lambda Xe - abd: 8.67 +/- 1.27 ml x g-1; P = 0.03). The influence of oedema on the local blood flow [in ml x (100 g x min)-1] and on the post-reconstructive hyperaemia (in ml x min-1) is discussed. It is concluded that local blood flow determinations, based on 133Xenon wash-out rates, in individual cases, are not possible. In subcutaneous tissue with low lipid contents, the ratio between the post- and preoperative wash-out rates tend to underestimate the post reconstructive hyperaemia. This is due to the volume increase of the subcutaneous tissue being larger than the decrease of the tissue-to-blood partition coefficient due to the oedema.