Wilmer W A, Voroshilova O, Singh I, Middendorf D F, Cosio F G
Department of Internal Medicine, Division of Nephrology, Ohio State University, Columbus, OH, USA.
Am J Kidney Dis. 2001 Apr;37(4):797-806. doi: 10.1016/s0272-6386(01)80129-3.
Calciphylaxis is a severe complication of chronic renal failure, confined almost exclusively to patients on dialysis therapy. Histological characteristics of calciphylaxis include small-vessel calcifications of skin, subcutaneous tissue, and visceral organs. These vascular changes promote tissue ischemia that often results in tissue necrosis. In this study, we investigated the extent of skin ischemia in patients with calciphylaxis by means of transcutaneous oxygen tension (TCPO(2)) measurement, a noninvasive test that accurately assesses skin oxygenation. TCPO(2) levels were measured in 21 patients with calciphylaxis and 21 age- and sex-matched patients without evidence of calciphylaxis (controls). TCPO(2) levels were measured bilaterally at the chest, anterior abdomen, and upper thigh while patients breathed room air and after a 30-minute exposure to 100% fraction of inspired oxygen (FIO(2)). Compared with controls, patients with calciphylaxis showed significantly lower TCPO(2) levels at each body region. In both controls and patients with calciphylaxis, lower TCPO(2) levels correlated with increased weight and use of hemodialysis. No correlation with serum parathyroid hormone (PTH), serum calcium, or serum phosphorus values was present, although 39% of the patients with calciphylaxis had markedly elevated PTH values (sixfold greater than normal; >300 pg/dL). Low TCPO(2) levels in patients with calciphylaxis were documented in body regions with and without skin lesions. In patients with calciphylaxis, extremely low TCPO(2) values (</=30 mm Hg while patients breathed room air) were present in 62% of the body regions with skin lesions and 26% of the body regions without lesions. Room-air TCPO(2) levels </=30 mm Hg were present in only 0.8% of the body regions of control patients. TCPO(2) levels obtained while patients breathed 100% FIO(2) remained lower in patients with calciphylaxis than in controls. In conclusion, TCPO(2) levels are abnormally low in patients with calciphylaxis, indicating that severe and diffuse skin ischemia exists, even at areas free of skin lesions. Low TCPO(2) values did not substantially increase with 100% FIO(2) in many patients with calciphylaxis, suggesting a fixed insufficiency of the skin vessels. This study shows that TCPO(2) measurements may allow rapid and noninvasive screening for skin ischemia before the development of skin lesions in patients with calciphylaxis.
钙过敏是慢性肾衰竭的一种严重并发症，几乎仅见于接受透析治疗的患者。钙过敏的组织学特征包括皮肤、皮下组织和内脏器官的小血管钙化。这些血管变化会导致组织缺血，进而常常引发组织坏死。在本研究中，我们通过经皮氧分压（TCPO₂）测量来研究钙过敏患者的皮肤缺血程度，这是一种能准确评估皮肤氧合情况的非侵入性检测方法。对21例钙过敏患者以及21例年龄和性别匹配且无钙过敏证据的患者（对照组）进行了TCPO₂水平测量。在患者呼吸室内空气时以及暴露于100%吸入氧分数（FIO₂）30分钟后，双侧测量胸部、前腹部和大腿上部的TCPO₂水平。与对照组相比，钙过敏患者在每个身体部位的TCPO₂水平均显著更低。在对照组和钙过敏患者中，较低的TCPO₂水平均与体重增加及血液透析的使用相关。尽管39%的钙过敏患者甲状旁腺激素（PTH）水平显著升高（比正常高六倍；>300 pg/dL），但TCPO₂水平与血清PTH、血清钙或血清磷值均无相关性。在有皮肤病变和无皮肤病变的身体部位均记录到钙过敏患者的TCPO₂水平较低。在钙过敏患者中，62%有皮肤病变的身体部位以及26%无病变的身体部位在呼吸室内空气时TCPO₂值极低（≤30 mmHg）。对照组患者身体部位中只有0.8%的呼吸室内空气时TCPO₂水平≤30 mmHg。在患者呼吸100% FIO₂时测得的TCPO₂水平，钙过敏患者仍低于对照组。总之，钙过敏患者的TCPO₂水平异常低，表明即使在无皮肤病变的区域也存在严重且弥漫性的皮肤缺血。在许多钙过敏患者中，100% FIO₂时TCPO₂值并未显著升高，提示皮肤血管存在固定性供血不足。本研究表明，TCPO₂测量可能有助于在钙过敏患者出现皮肤病变之前快速且非侵入性地筛查皮肤缺血情况。
