維他命C可降低高壓氧誘發之疼痛－－病例報告

Ascorbic acid alleviate hyperbaric oxygen therapy induced pain

週邊動脈阻塞性疾病（PAOD）是常見的缺血性疼痛的原因之一，其特徵是休息時持續性的疼痛，並伴隨有局部缺血潰瘍，以及困難癒合的傷口。高壓氧是其中一種可用來治療這些病人的方式之一，且其通常可使疾病改善。然而，一名過去即患有週邊動脈阻塞性疾病的36歲男性，手指缺血性疼痛的強度大約是4分（滿分10分），來到了本院疼痛門診求診：因為在接受高壓氧治療時，其手指的疼痛強度更形增加（7分）。傳統的藥物治療，包括類鴉片類止痛劑，都無法使他獲得滿意的止痛效果。在與病人討論過後，我們建議在接下來的兩次高壓氧治療的三十分鐘前，另加維他命C500毫克作為高壓氧引發疼痛的輔助治療。接受這個建議後，我們發現病人在接受接下來兩次的高壓氧治療中，疼痛的強度可由7分降到4分，因此他能忍受在高壓氧艙中接受治療。我們將探討接受高壓氧時引發疼痛的機轉，以及維他命C降低此疼痛的可能原因。高壓氧可能會引發血中自由基的濃度上升，而抗氧化劑維他命c可降低自由基的量，可能是用來解釋此病人情況最可能的原因。

Peripheral arterial occlusive disease (PAOD) is one of common etiologies of ischemic pain, which is characterized with resting pain, focal ischemic ulceration, and impaired wound healing. Hyperbaric oxygen therapy (HBO) is one of the therapeutic choices for these patients and usually it improved disease process. We report a 36-year-old male suffering from intractable resting pain, Visual Analogue Score (VAS) 6, over bilateral fingers due to PAOD. The pain was much worse during HBO therapy and could not be relieved with pharmacologic analgesics even opioids. After discussion, he accepted our recommendation to take additional vitamin C 500 mg as an adjunct therapy just 30 min before HBO therapy. During the next two HBO therapies, his pain was alleviated obviously with VAS score reduction from 7 to 4. He was satisfied with the analgesic effect and able to tolerate in the HBO chamber. HBO may induce elevation of serum free radical level and Vitamin C, an antioxidant agent, could reduce its elevation, which was thought to be the most possible explanation for the pain relief in this patient. The mechanism of HBO induced pain and the effect of Vitamin C treatment will be discussed.