{"id":19140,"date":"2020-09-21T05:00:00","date_gmt":"2020-09-20T21:00:00","guid":{"rendered":"http:\/\/csccm.org.cn\/?p=19140"},"modified":"2020-09-26T07:27:10","modified_gmt":"2020-09-25T23:27:10","slug":"life-in-the-fast-lane-%e6%b0%a7%e9%a5%b1%e5%92%8c%e5%ba%a6%e5%88%86%e7%a6%bb","status":"publish","type":"post","link":"https:\/\/csccm.org.cn\/?p=19140","title":{"rendered":"[Life in the Fast Lane]: \u6c27\u9971\u548c\u5ea6\u5206\u79bb(3\/4)"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">Dissociated Oxygen Saturations<\/h1>\n\n\n\n<p>by&nbsp;<a href=\"https:\/\/litfl.com\/author\/paul-young\/\">Dr Paul Young<\/a>, last update&nbsp;March 16, 2019<\/p>\n\n\n\n<p>aka&nbsp;<a href=\"https:\/\/litfl.com\/clinical-cases\/hematology-hoodwinker\/\">Hematology Hoodwinker<\/a>&nbsp;004<\/p>\n\n\n\n<p>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<p>\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<p>This is the arterial blood gas:<\/p>\n\n\n\n<p>\u60a3\u8005\u52a8\u8109\u8840\u6c14\u7ed3\u679c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/litfl.com\/wp-content\/uploads\/2019\/01\/PY-blood-gas-1.jpg\" alt=\"\"\/><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\">Questions \u95ee\u9898<\/h4>\n\n\n\n<p>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<p>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<p>A1. Answer and interpretation<\/p>\n\n\n\n<p>A1. \u56de\u7b54\u4e0e\u89e3\u91ca<\/p>\n\n\n\n<p><strong>Possible explanations<\/strong>&nbsp;for \u2018pseudo-hypoxaemia\u2019 include<\/p>\n\n\n\n<p>\u5047\u6027\u4f4e\u6c27\u8840\u75c7\u7684\u53ef\u80fd\u539f\u56e0\u5305\u62ec<\/p>\n\n\n\n<ul><li>Equipment failure<br \/>\u2014 faulty pulse oximeter<br \/>\u2014 faulty blood gas analyser<\/li><li>Blood sample used was actually venous<\/li><li>Blood sample taken from a site affected by localised hypoxemia, e.g. ischaemic limb<\/li><li>Excessive oxygen consumption following blood sample collection (e.g. massive leukocytosis or thrombocytosis)<\/li><\/ul>\n\n\n\n<ul><li>\u8bbe\u5907\u6545\u969c<br \/>\u2014 \u8109\u640f\u6c27\u9971\u548c\u5ea6\u4eea\u9519\u8bef<br \/>\u2014 \u8840\u6c14\u5206\u6790\u4eea\u9519\u8bef<\/li><li>\u4f7f\u7528\u7684\u8840\u6db2\u6807\u672c\u4e3a\u9759\u8109\u8840<\/li><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><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<p>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<p>\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<ul><li>In carbon monoxide poisoning SpO2 will read in the 90s despite high levels of COHb \u2014 but the PaO2 should still be high.<\/li><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<ul><li>\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><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<p>Q2. What other blood test would be particularly helpful?<\/p>\n\n\n\n<p>Q2. \u5176\u4ed6\u54ea\u4e9b\u8840\u6db2\u68c0\u67e5\u7ed3\u679c\u4f1a\u6709\u5e2e\u52a9\uff1f<\/p>\n\n\n\n<p>A2. Answer and interpretation<\/p>\n\n\n\n<p>A2. \u56de\u7b54\u4e0e\u89e3\u91ca<\/p>\n\n\n\n<p><strong>The full blood count<\/strong><\/p>\n\n\n\n<p>\u5168\u8840\u7ec6\u80de\u8ba1\u6570<\/p>\n\n\n\n<p>This is what the patient\u2019s blood test showed:<\/p>\n\n\n\n<p>\u4ee5\u4e0b\u662f\u60a3\u8005\u8840\u6db2\u68c0\u67e5\u7ed3\u679c\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/litfl.com\/wp-content\/uploads\/2019\/01\/PY-FBC-1.jpg\" alt=\"\"\/><\/figure>\n\n\n\n<p>Q3. Describe the blood test result shown in Q2?<\/p>\n\n\n\n<p>Q3. \u8bf7\u63cf\u8ff0Q2\u4e2d\u8840\u6db2\u68c0\u67e5\u7ed3\u679c<\/p>\n\n\n\n<p>A3. Answer and Interpretation<\/p>\n\n\n\n<p>A3. \u7b54\u6848\u4e0e\u89e3\u91ca<\/p>\n\n\n\n<p>The key findings are<\/p>\n\n\n\n<p>\u4e3b\u8981\u53d1\u73b0\u4e3a\uff1a<\/p>\n\n\n\n<ul><li><strong>massive leukocytosis<\/strong>, due to a large number of blasts<\/li><li>normocytic\u00a0<strong>anemia<\/strong>\u00a0(Hb 98 with normal MCHC), mild macrocytosis (MCV 98) and increased RDW (17.9)<\/li><li><strong>thrombocytopenia<\/strong><\/li><\/ul>\n\n\n\n<ul><li>\u56e0\u4e3a\u5927\u91cf\u6bcd\u7ec6\u80de\u9020\u6210\u7684<strong>\u91cd\u5ea6\u767d\u7ec6\u80de\u589e\u591a\u75c7<\/strong><\/li><li>\u6b63\u5e38\u7ec6\u80de\u6027\u8d2b\u8840\uff08Hb 98\u4e14MCHC\u6b63\u5e38\uff09\uff0c\u7ea2\u7ec6\u80de\u8f7b\u5ea6\u589e\u5927(MCV 98)\uff0cRDW\u5347\u9ad8 (17.9)<\/li><li><strong>\u8840\u5c0f\u677f\u7f3a\u4e4f<\/strong><\/li><\/ul>\n\n\n\n<p>Spurious hypoxaemia in this setting is also known as \u2018leukocyte larceny\u2019.<\/p>\n\n\n\n<p>\u672c\u4f8b\u4e2d\u5047\u6027\u4f4e\u6c27\u8840\u75c7\u4e5f\u88ab\u79f0\u4e3a\u201c\u767d\u7ec6\u80de\u76d7\u7a83\u201d\u3002<\/p>\n\n\n\n<p>Q4. Interpret the blood test result shown in Q2? What is the likely underlying diagnosis?<\/p>\n\n\n\n<p>Q4. \u89e3\u91caQ2\u4e2d\u8840\u6db2\u68c0\u67e5\u7ed3\u679c\uff1f\u6700\u53ef\u80fd\u7684\u8bca\u65ad\u662f\u4ec0\u4e48\uff1f<\/p>\n\n\n\n<p>A4. Answer and Interpretation<\/p>\n\n\n\n<p>A4. \u7b54\u6848\u4e0e\u89e3\u91ca<\/p>\n\n\n\n<p><strong>Acute myeloid leukemia<\/strong><\/p>\n\n\n\n<p>\u6025\u6027\u9ad3\u7cfb\u767d\u8840\u75c5<\/p>\n\n\n\n<p><strong>Hyperleukocytosis<\/strong>\u00a0(>100 x 10E9\/L) is almost always due to a\u00a0<strong>hematological malignancy<\/strong>.<\/p>\n\n\n\n<p><strong>\u767d\u7ec6\u80de\u589e\u591a<\/strong>\u00a0(>100 x 10E9\/L) \u51e0\u4e4e\u603b\u662f\u7531\u4e8e\u8840\u6db2\u7cfb\u7edf\u6076\u6027\u80bf\u7624\u9020\u6210\u3002<\/p>\n\n\n\n<p><strong>Blast cells<\/strong>\u00a0in the blood suggest acute leukemia or a blast cell crisis. The presence of\u00a0<a href=\"http:\/\/www.pathologystudent.com\/?p=16\">Auer rods<\/a>\u00a0in the blast cells would confirm the diagnosis of acute myeloid leukemia. Blast cell crisis occurs when chronic myeloid leukemia (CML) undergoes transformation into a more aggressive condition.<\/p>\n\n\n\n<p>\u8840\u6db2\u4e2d\u7684\u6bcd\u7ec6\u80de\u63d0\u793a\u4e3a\u6025\u6027\u767d\u8840\u75c5\u6216\u6bcd\u7ec6\u80de\u5371\u8c61\u3002\u6bcd\u7ec6\u80de\u5185\u53d1\u73b0Auer\u5c0f\u4f53\u53ef\u4ee5\u786e\u8bca\u6025\u6027\u9ad3\u7cfb\u767d\u8840\u75c5\u3002\u6162\u6027\u9ad3\u7cfb\u767d\u8840\u75c5(CML)\u53d1\u751f\u6025\u53d8\u65f6\u5373\u53ef\u51fa\u73b0\u6bcd\u7ec6\u80de\u5371\u8c61\u3002<\/p>\n\n\n\n<blockquote class=\"wp-block-quote\"><p>Blast cells are immature precursors of either lymphocytes (lymphoblasts), or granulocytes (myeloblasts). They do not normally appear in peripheral blood. They can be recognized microscopically by their large size and primitive nuclei (ie the nuclei contain nucleoli).<\/p><\/blockquote>\n\n\n\n<p>The anemia and thrombocytopenia is consistent with bone marrow failure.<\/p>\n\n\n\n<p>\u8d2b\u8840\u4e0e\u8840\u5c0f\u677f\u7f3a\u4e4f\u4e0e\u9aa8\u9ad3\u529f\u80fd\u8870\u7aed\u76f8\u7b26\u5408\u3002<\/p>\n\n\n\n<p>Q5. What other complications is this patient at risk of?<\/p>\n\n\n\n<p>Q5. \u6b64\u4f8b\u60a3\u8005\u8fd8\u53ef\u80fd\u51fa\u73b0\u4ec0\u4e48\u5176\u4ed6\u5e76\u53d1\u75c7\uff1f<\/p>\n\n\n\n<p>Q6. What are the treatment options?<\/p>\n\n\n\n<p>Q6. \u6cbb\u7597\u9009\u62e9\u6709\u54ea\u4e9b\uff1f<\/p>\n\n\n\n<p>Q7. How could the abnormal blood gas result be avoided?<\/p>\n\n\n\n<p>Q7. \u5982\u4f55\u907f\u514d\u5f97\u5230\u5f02\u5e38\u8840\u6c14\u7ed3\u679c\uff1f<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Dissociated Oxygen Saturations by&nbsp;Dr Paul Young, l [&hellip;]<\/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\/19140"}],"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=19140"}],"version-history":[{"count":7,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts\/19140\/revisions"}],"predecessor-version":[{"id":19154,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts\/19140\/revisions\/19154"}],"wp:attachment":[{"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=19140"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=19140"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=19140"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}