{"id":19143,"date":"2020-09-14T05:10:02","date_gmt":"2020-09-13T21:10:02","guid":{"rendered":"http:\/\/csccm.org.cn\/?p=19143"},"modified":"2020-09-22T09:47:58","modified_gmt":"2020-09-22T01:47:58","slug":"life-in-the-fast-lane-%e6%b0%a7%e9%a5%b1%e5%92%8c%e5%ba%a6%e5%88%86%e7%a6%bb2-4","status":"publish","type":"post","link":"https:\/\/csccm.org.cn\/?p=19143","title":{"rendered":"[Life in the Fast Lane]: \u6c27\u9971\u548c\u5ea6\u5206\u79bb(2\/4)"},"content":{"rendered":"\n

Dissociated Oxygen Saturations<\/h1>\n\n\n\n

by Dr Paul Young<\/a>, last update March 16, 2019<\/p>\n\n\n\n

aka Hematology Hoodwinker<\/a> 004<\/p>\n\n\n\n

One of the emergency residents has just taken an ABG on the 44 year-old woman in cubicle 3. Prior to her current presentation she had no known medical problems. The patient\u2019s pulse oximetry reading is SpO2 98% on air.<\/p>\n\n\n\n

\u6025\u8bca\u79d1\u7684\u4e00\u540d\u4f4f\u9662\u533b\u5e08\u521a\u521a\u4e3a\u4e00\u540d44\u5c81\u7684\u5973\u6027\u60a3\u8005\u505a\u4e86\u52a8\u8109\u8840\u6c14\u68c0\u67e5\u3002\u6b64\u6b21\u53d1\u75c5\u524d\uff0c\u60a3\u8005\u6ca1\u6709\u65e2\u5f80\u75c5\u53f2\u3002\u60a3\u8005\u5438\u7a7a\u6c14\u65f6\u8109\u640f\u6c27\u9971\u548c\u5ea6(SpO2)\u4e3a98%\u3002<\/p>\n\n\n\n

This is the arterial blood gas:<\/p>\n\n\n\n

\u60a3\u8005\u52a8\u8109\u8840\u6c14\u7ed3\u679c\u5982\u4e0b\uff1a<\/p>\n\n\n\n

\"\"\/<\/figure>\n\n\n\n

Questions \u95ee\u9898<\/h4>\n\n\n\n

Q1. What are the possible explanations for the discrepancy between the pulse oximetry reading and the oxygen saturation on the arterial blood gas?<\/p>\n\n\n\n

Q1. \u8109\u640f\u6c27\u9971\u548c\u5ea6\u4e0e\u52a8\u8109\u8840\u6c14\u6c27\u9971\u548c\u5ea6\u7ed3\u679c\u4e0d\u4e00\u81f4\u7684\u53ef\u80fd\u539f\u56e0\u6709\u54ea\u4e9b\uff1f<\/p>\n\n\n\n

A1. Answer and interpretation<\/p>\n\n\n\n

A1. \u56de\u7b54\u4e0e\u89e3\u91ca<\/p>\n\n\n\n

Possible explanations<\/strong> for \u2018pseudo-hypoxaemia\u2019 include<\/p>\n\n\n\n

\u5047\u6027\u4f4e\u6c27\u8840\u75c7\u7684\u53ef\u80fd\u539f\u56e0\u5305\u62ec<\/p>\n\n\n\n

  • Equipment failure
    \u2014 faulty pulse oximeter
    \u2014 faulty blood gas analyser<\/li>
  • Blood sample used was actually venous<\/li>
  • Blood sample taken from a site affected by localised hypoxemia, e.g. ischaemic limb<\/li>
  • Excessive oxygen consumption following blood sample collection (e.g. massive leukocytosis or thrombocytosis)<\/li><\/ul>\n\n\n\n
    • \u8bbe\u5907\u6545\u969c
      \u2014 \u8109\u640f\u6c27\u9971\u548c\u5ea6\u4eea\u9519\u8bef
      \u2014 \u8840\u6c14\u5206\u6790\u4eea\u9519\u8bef<\/li>
    • \u4f7f\u7528\u7684\u8840\u6db2\u6807\u672c\u4e3a\u9759\u8109\u8840<\/li>
    • \u91c7\u53d6\u8840\u6db2\u6807\u672c\u7684\u90e8\u4f4d\u53d7\u5230\u5c40\u90e8\u4f4e\u6c27\u8840\u75c7\u7684\u5f71\u54cd\uff0c\u5982\u80a2\u4f53\u7f3a\u8840<\/li>
    • \u8840\u6db2\u6807\u672c\u91c7\u96c6\u540e\u8fc7\u5ea6\u6c27\u8017\uff08\u5982\u4e25\u91cd\u7684\u767d\u7ec6\u80de\u589e\u591a\u75c7\u6216\u8840\u5c0f\u677f\u589e\u591a\u75c7\uff09<\/li><\/ul>\n\n\n\n

      Dyshemoglobinemia can also cause a discrepancy between SpO2 and SaO2, but will not cause the decrease in measured PaO2 as seen in this case.<\/p>\n\n\n\n

      \u5f02\u5e38\u8840\u7ea2\u86cb\u767d\u8840\u75c7\u4e5f\u53ef\u4ee5\u5bfc\u81f4SpO2 \u4e0e SaO2 \u4e0d\u4e00\u81f4\uff0c\u4f46\u4e0d\u4f1a\u5f15\u8d77\u672c\u4f8b\u770b\u5230\u7684PaO2\u964d\u4f4e\u3002<\/p>\n\n\n\n

      • In carbon monoxide poisoning SpO2 will read in the 90s despite high levels of COHb \u2014 but the PaO2 should still be high.<\/li>
      • In methemoglobinemia, the SpO2 plateaus at about 86% with increasing levels of MetHb, but again the PaO2 will not be decreased.<\/li><\/ul>\n\n\n\n
        • \u4e00\u6c27\u5316\u78b3\u4e2d\u6bd2\u65f6\uff0cSpO2\u53ef\u80fd\u4ec5\u4e3a90%\uff0c\u5c3d\u7ba1COHb\u6c34\u5e73\u5f88\u9ad8 \u2014 \u4f46PaO2 \u4ecd\u7136\u5e94\u5f53\u5f88\u9ad8<\/li>
        • \u9ad8\u94c1\u8840\u7ea2\u86cb\u767d\u65f6\uff0c\u968f\u7740MetHb\u6c34\u5e73\u4e0d\u65ad\u5347\u9ad8\uff0cSpO2\u572886%\u8fbe\u5230\u5e73\u53f0\uff0c\u4f46PaO2\u540c\u6837\u4e0d\u4f1a\u964d\u4f4e<\/li><\/ul>\n\n\n\n

          Q2. What other blood test would be particularly helpful?<\/p>\n\n\n\n

          Q2. \u5176\u4ed6\u54ea\u4e9b\u8840\u6db2\u68c0\u67e5\u7ed3\u679c\u4f1a\u6709\u5e2e\u52a9\uff1f<\/p>\n\n\n\n

          A2. Answer and interpretation<\/p>\n\n\n\n

          A2. \u56de\u7b54\u4e0e\u89e3\u91ca<\/p>\n\n\n\n

          The full blood count<\/strong><\/p>\n\n\n\n

          \u5168\u8840\u7ec6\u80de\u8ba1\u6570<\/p>\n\n\n\n

          This is what the patient\u2019s blood test showed:<\/p>\n\n\n\n

          \u4ee5\u4e0b\u662f\u60a3\u8005\u8840\u6db2\u68c0\u67e5\u7ed3\u679c\uff1a<\/p>\n\n\n\n

          \"\"\/<\/figure>\n\n\n\n

          Q3. Describe the blood test result shown in Q2?<\/p>\n\n\n\n

          Q3. \u8bf7\u63cf\u8ff0Q2\u4e2d\u8840\u6db2\u68c0\u67e5\u7ed3\u679c<\/p>\n\n\n\n

          Q4. Interpret the blood test result shown in Q2? What is the likely underlying diagnosis?<\/p>\n\n\n\n

          Q4. \u89e3\u91caQ2\u4e2d\u8840\u6db2\u68c0\u67e5\u7ed3\u679c\uff1f\u6700\u53ef\u80fd\u7684\u8bca\u65ad\u662f\u4ec0\u4e48\uff1f<\/p>\n","protected":false},"excerpt":{"rendered":"

          Dissociated Oxygen Saturations by Dr Paul Young, l […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[13,18],"tags":[],"_links":{"self":[{"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts\/19143"}],"collection":[{"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=19143"}],"version-history":[{"count":1,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts\/19143\/revisions"}],"predecessor-version":[{"id":19152,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts\/19143\/revisions\/19152"}],"wp:attachment":[{"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=19143"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=19143"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=19143"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}