Case Discussion This 32-year-old woman was diagnosed as AML in Apr 1999, with an initial presentation of easy bruising. She underwent allogeneic bone marrow transplantation in Feb 2000.The post-BMT course was complicated by GVHD, pulmonary TB, interstitial pneumonitis and steroid myopathy. HRCT showed bronchiectasis with peribronchial thickening. She was in a depressed mood in Aug 2002 due to corneal ulcer. On Sep 23, 2002, she was found lying unconscious in her room and burned coal was found nearby. She was sent to a local hospital where respiratory acidosis was found. Some unknown drugs were also found in the trashcan. Because of suspected CO intoxication, she was referred to the ER of a teaching hospital where fever, hypotension, and tachycardia were noted. The blood gas analysis showed respiratory acidosis and the HbCO was 25.8%. She was intubated and transferred to the ICU for further care.  體檢發現(Evident Physical findings): Consciousness: drowsy but oriented BP 130/71mmHg (Dopamine 20ug/Kg/min); T/P/R 37.6/135/18 HEENT: conjunctiva not pale; anicteric sclerae Neck: supple; no LAP or JVE Chest: symmetric expansion; clear breath sound Heart: RHB; no murmur Abdomen: soft and flat; normoactive bowel sounds; no organomegaly Extremity: freely movable; no cyanosis or edema Skin color : no specific change 住院治療經過(Course and Management): The CxR (Figure 1 ) revealed only mild interstitial infiltrates over both lower lung fields, which did not differ from her previous films. The follow-up HbCO level on Sep. 23 was 0%. She was extubated on Sep. 24. However, there was still CO2 retention and dyspnea was noted. Intermittent BiPAP support was instituted. She was transferred to general ward on Sep. 26. The bronchodilator test showed severe obstructive defect without response to inhaled β 2-agonist. She was discharged on Oct 2 in a stable condition. 呼吸治療經過  日期 時間 9/23 10:50 16:00 9/24 08:50 14:00 9/26 09:00 Mode ACMV ACMV PSV Mask Mask PEEP 10 10 5     FiO2 1.0 1.0 0.58 0.98 0.4 pH 7.36 7.446 7.282 7.296 PaCO2 35.2 27.1   54.1 55.9 PaO2 402.1 145.6   349.1 72.1 HCO2 19.4 18.2   25 26.6 BE -4.8 -4.1   -2.6 -0.9 SpO2 100 100 96 98 98 備註 COHb=25.8   RR=31 VT=265 RSI=117 COHb=0 13:30拔管 BiPAP standby 9/26 3pm 轉病房     說明 此案例敘述一個32歲的女性病患因為燃燒木炭嘗試自殺。被發現時意識不清，經轉送到醫院緊急處理，住院數天後平安出院。 由於一氧化碳對血色素的親合力為氧氣的200倍以上，因此會搶先與氧氣結合而形成一氧化碳血色素(Carboxyhemoglobin, HbCO)，體內組織由於無氧可用便造成缺氧反應。一氧化碳中毒的症狀可能包括頭痛、頭昏、噁心、嘔吐、心悸、眼花、四 肢無力、嗜睡、心肌梗塞、心律不整、昏迷、抽搐及死亡等不同表現。另外有部分病人在恢復意識後，經過一段時間又發生 遲發性腦病變，而有智能減退、大小便失禁、步態不穩、行為退化等症狀出。昏迷時間過久，可能會留下腦部受損的後遺症。 一氧化碳中毒的症狀繁多且千變萬化，容易被忽略，有些病人可能因不明原因的頭痛，而作了許多檢查仍查不出病因，後來 才發現為一氧化碳中毒；另外，在初期可能被誤以為中風、心肌缺氧或梗塞，而失去治療的黃金時機。診斷用的 cherry-red skin並不常見。 發現一氧化碳中毒者，應立即將病人移至通風處，並迅速送醫急救。病患送醫院後得馬上檢測一氧化碳血紅素濃度，治療 上可給予100%O2，病人意識、噁心、胸悶等現象就會逐漸改善。HbCO > 25%，或有心臟血管疾患且 HbCO>15%，或懷 孕婦女且HbCO＞10%以上須住院。若有高壓艙氧氣設備，可給3大氣壓100% O21小時。一氧化碳血紅素濃度如 高於40%以上，病人意識則呈昏迷狀態，此時最好使用高壓氧艙，約二十分鐘，其濃度就會減半。 繼續教育考題 1. (D) 一氧化碳中毒之臨床表徵包括: A 頭痛 B 噁心、嘔吐 C 前額昏迷 D 以上皆是 2. (C) 一氧化碳中毒之症狀，下列何者為非? A 中毒症狀繁多且千變萬化 B 一氧化碳濃度> 30%可使判斷力變差、噁心、頭暈、視覺異常 C 常見cherry-red skin D 嚴重者可死亡 3. (D) 一氧化碳中毒之之合併症包括有下列何者? A 抽搐 B 心肌梗塞、心律不整 C 遲發性腦病變而使智能減退 D 以上皆是 4. (C) 一氧化碳對血色素的親合力為氧氣的幾倍以上? A 5倍以上 B 20倍以上  C 200倍以上 D 400倍以上 5. (D) 一氧化碳中毒時一氧化碳濃度以上須住院?  A HbCO > 25% B 心臟血管疾患之HbCO>15% C 懷孕婦女 HbCO＞10% D 以上皆是 6. (A) 一氧化碳中毒時 pulse oximetry (SpO2)數值與實際PaO2比較常為 A 高估 B 低估 C SpO2仍為可信 D 以上皆非 7. (D) 一氧化碳中毒之可有哪些laboratory findings? A ABG : metabolic acidosis B  lactic acid 上升 C PaO2下降 D 以上皆是 8. (D) 發現一氧化碳中毒之處理處理下列何者為是? A 應立即將病人移至通風處，並迅速送醫急救 B 病患送醫院後得馬上檢測一氧化碳血紅素濃度 C 治療上可給予100% O2， D 以上皆是 9. (D) 除了Hb以外，一氧化碳還可與何者結合? A  cardiac myoglobin B cytochrome C C P450 type cytochrome D 以上皆是 10. (D) 有關一氧化碳血色素(Carboxyhemoglobin, HbCO)之半衰期 (half life)下列何者為是? A  HbCO半衰期於吸room air時為240-320 分鐘 B 100% O2 可使HbCO之半衰期縮短 C 高壓氧氣可使HbCO 之半衰期縮短為20分 D 以上皆是

答案解說 (D)  中毒的症狀可能包括頭痛、頭昏、噁心、嘔吐、心悸、眼花、四肢無力、嗜睡、心肌梗塞、心律不整、昏迷、抽搐及死亡 (C )  Cherry-red skin並不常見。 (D )  所有敘述皆正確. Following severe intoxication, patients may display CNS pathology, including white matter demyelination leading to edema and focal areas of necrosis, (C )   (D ) 所有敘述皆正確(如說明) (A)  SpO2數值與實際PaO2比較常高估 (因Hb-O2 saturation curve left shifting的緣故 (The binding of CO to hemoglobin causes an increased binding of oxygen molecules at the other 3 oxygen binding sites, causing a leftward shift in the oxyhemoglobin dissociation curve and decreasing the availability of oxygen to the already hypoxic tissues). (D )  所有敘述皆正確(如說明) (D) 發現一氧化碳中毒者應立即將病人移至通風處，並迅速送醫急救。病患送醫院後得馬上檢測一氧化碳血紅素濃度，治療上可給予100% O2 (D)  CO binds to cardiac myoglobin with an even greater affinity than to hemoglobin. The resulting myocardial depression and hypotension exacerbates the tissue hypoxia. CO also binds to cytochrome C and P450 type cytochromes but with a much lower affinity than that of oxygen (D)  Hyperbaric oxygen provides tissue oxygenation by dissolving oxygen in plasma shortens the half-life of carboxyhemoglobin from 240-320 minutes to 20 minutes and dissociates carbon monoxide from cytochrome c oxidase.