Toxicity, Carbon Monoxide 中山医院急诊科姚晨玲
Toxicity, Carbon Monoxide 中山医院急诊科 姚晨玲
Background Carbon monoxide (co)is a colorless odorless gas produced by incomplete combustion of carbonaceous material Co is formed as a by-product of burning organic compounds
Background ◼ Carbon monoxide (CO) is a colorless, odorless gas produced by incomplete combustion of carbonaceous material ◼ CO is formed as a by-product of burning organic compounds
Pathophysiology a Co toxicity causes impaired oxygen delivery and utilization a CO reversibly binds hemoglobin, resulting in relative anemia Co binds hemoglobin 230-260 times more avidly than oxygen dissociation of co from Hbco is slow than that of o2 from Hbo2(1/3600)
Pathophysiology ◼ CO toxicity causes impaired oxygen delivery and utilization ◼ CO reversibly binds hemoglobin, resulting in relative anemia. – CO binds hemoglobin 230-260 times more avidly than oxygen. – dissociation of CO from HbCO is slow than that of O2 from HbO2 (1/3600)
Pathophysiology Resulting a leftward shift in the oxyhemoglobin dissociation curve a binds to cardiac myoglobin, resulting myocardial depression and hypotension a Co binds to cytochromes c and P450 impaired oxygen utilization at the cellular level
Pathophysiology ◼ Resulting a leftward shift in the oxyhemoglobin dissociation curve ◼ binds to cardiac myoglobin , resulting myocardial depression and hypotension ◼ CO binds to cytochromes c and P450, impaired oxygen utilization at the cellular level
100 90 o.5po co 液80 70 碳氧 60 0.1%CO 血L 红50 蛋40 0.05%CO 白 %30 20 0.01%CO 10 345 8 910 寸间(h) 图10-2-4血液中HbOO%与空气中 CO浓度和接触时间的关系
Clinical Acute carbon monoxide poisoning Mild poisoning COHb level: 10%-20% Headache nausea vomiting fatigue Moderate poisoning ·COHb|eve|:30%-40% Confusion Agitation hallucination Visual disturbance syncope, seIzure Skin: Classic cherry red skin is rare(ie,"When you're cherry red, you're dead); pallor is present more often Severe poisoning · COHb leve|:40%-60% Noncardiogenic pulmonary edema, arrhythmia Papilledema
Clinical ◼ Acute carbon monoxide poisoning – Mild poisoning • COHb level :10%-20%. • Headache, nausea, vomiting, fatigue. – Moderate poisoning • COHb level :30%-40%. • Confusion, Agitation, Hallucination, Visual disturbance, syncope, seizure • Skin: Classic cherry red skin is rare (ie, “When you're cherry red, you're dead”); pallor is present more often. – Severe poisoning • COHb level :40%-60%. • Noncardiogenic pulmonary edema, arrhythmia, Papilledema
Clinical a delayed neuropsychiatric symptoms Long-term exposures or severe acute exposures frequently result in long-term neuropsychiatric sequelae. Additionally, some individuals develop delayed neuropsychiatric symptoms, often after severe intoxications associated with coma(about 3%-10%of all patients) After 2-60days"normal period, chronic headaches, memory problems, and parkinsonian type tremor, re-occur
◼ delayed neuropsychiatric symptoms – Long-term exposures or severe acute exposures frequently result in long-term neuropsychiatric sequelae. Additionally, some individuals develop delayed neuropsychiatric symptoms, often after severe intoxications associated with coma (about 3%-10% of all patients) – After 2-60days “normal period” , chronic headaches, memory problems, and parkinsoniantype tremor, re-occur . Clinical
delayed neuropsychiatric symptoms 「病例介绍]年近半百的李某,湖南常宁市人,在新疆打工 202年11月27日晚,李某和另外2人睡在生火炉的房内,次 日被人发现因煤气中毒昏迷,生命垂危。患者立即被送入 医院进行高压氧治疗1次后,均神志清楚。李某于11月29日 自行乘火车返回湖南常宁,回家后生活尚能自理就未再进 行其他治疗。约20天后,李某开始出现少气懒言、情感淡 漠、反应迟钝等症状,而且外出后不知道回家。家人以为 他中了“邪”,先后请巫婆念咒“安神”、“驱鬼”,患 者不仅不见好转,反而四肢瘫软,卧床不起,大小便失禁 完全失语…本月上旬,患者被送入湘雅医院,诊断为急 性一氧化碳中毒迟发性脑病。给予高压氧及细胞活化剂治 疗目前患者病情已有好转
delayed neuropsychiatric symptoms [病例介绍] 年近半百的李某，湖南常宁市人，在新疆打工。 2002年11月27日晚，李某和另外2人睡在生火炉的房内，次 日被人发现因煤气中毒昏迷，生命垂危。患者立即被送入 医院进行高压氧治疗1次后，均神志清楚。李某于11月29日 自行乘火车返回湖南常宁，回家后生活尚能自理就未再进 行其他治疗。约20天后，李某开始出现少气懒言、情感淡 漠、反应迟钝等症状，而且外出后不知道回家。家人以为 他中了“邪”，先后请巫婆念咒“安神”、“驱鬼”，患 者不仅不见好转，反而四肢瘫软，卧床不起，大小便失禁， 完全失语……本月上旬，患者被送入湘雅医院，诊断为急 性一氧化碳中毒迟发性脑病。给予高压氧及细胞活化剂治 疗目前患者病情已有好转
Lab studies HbCo analysis Elevated levels are significant; however low levels do not rule out exposure, especially if the patient already has received 100% oXygen or if significant time (8h) has elapsed since exposure
Lab Studies ◼ HbCO analysis – Elevated levels are significant; however, low levels do not rule out exposure, especially if the patient already has received 100% oxygen or if significant time (8h) has elapsed since exposure
Lab studies ■ Arteria| blood gas Pao2 levels should remain normal. OXygen saturation is accurate only if directly measured but not if calculated from pao which is common in many blood gas analyzers PCO2 levels is normal or mildly decreased
◼ Arterial blood gas – PaO2 levels should remain normal. Oxygen saturation is accurate only if directly measured but not if calculated from PaO2 , which is common in many blood gas analyzers. – PCO2 levels is normal or mildly decreased Lab Studies