{"id":19041,"date":"2020-08-01T05:16:12","date_gmt":"2020-07-31T21:16:12","guid":{"rendered":"http:\/\/csccm.org.cn\/?p=19041"},"modified":"2020-08-05T07:06:30","modified_gmt":"2020-08-04T23:06:30","slug":"deranged-physiology%e6%96%87%e7%ab%a0-%e9%85%b8%e7%a2%b1%e5%88%86%e6%9e%90%e7%9a%84stewart%e7%89%a9%e7%90%86%e5%8c%96%e5%ad%a6%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/csccm.org.cn\/?p=19041","title":{"rendered":"[Deranged Physiology\u6587\u7ae0]: \u9178\u78b1\u5206\u6790\u7684Stewart\u7269\u7406\u5316\u5b66\u65b9\u6cd5"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">Stewart's physicochemical approach to acid-base analysis<\/h1>\n\n\n\n<p>Stewart's approach is a mathematically coherent explanation of acid-base balance, which allows one to&nbsp;make precise predictions regarding the interactions of the numerous interacting variables which affect pH.&nbsp;Laws&nbsp;governing the behaviour of aqueous solutions can be used to create&nbsp;equations&nbsp;which describe these interactions.&nbsp;&nbsp;In their model answer&nbsp;for&nbsp;<a href=\"https:\/\/derangedphysiology.com\/main\/node\/283\">Question 24<\/a>&nbsp;from the first paper of 2014, the college examiners commented that they only expected \"<em>an overall understanding of the principles involved\".&nbsp;<\/em>Most trainees possess this understanding; however, the&nbsp;pass rate was only 5.7%.&nbsp;The main problem was therefore&nbsp;a failure to&nbsp;articulate this knowledge into a coherent answer. &nbsp;This chapter&nbsp;ambitiously compacts a concept requiring&nbsp;<a href=\"http:\/\/www.lulu.com\/shop\/john-a-kellum-and-paul-wg-elbers\/stewarts-textbook-of-acid-base\/paperback\/product-4239943.html\">a 504-page book<\/a>&nbsp;to explain into a 10-minute SAQ answer or a sixty-second viva.<\/p>\n\n\n\n<p>In its briefest form:<\/p>\n\n\n\n<ul><li>The acid-base system is an interaction of several variables<\/li><li>There are independent variables, which can be altered from outside the system.<\/li><li>There are dependent variables which are altered by changes in the independent variables.<\/li><li>pH and HCO<sub>3<\/sub><sup>-<\/sup>&nbsp;are dependent variables.<\/li><li>The&nbsp;<strong>independent variables<\/strong>&nbsp;are:<ul><li>SID - the strong ion difference<\/li><li>A<sub>TOT<\/sub>&nbsp;- the total weak acid concentration<\/li><li>PaCO<sub>2<\/sub><\/li><\/ul><\/li><\/ul>\n\n\n\n<ul><li>Thus, changes in any of the independent variables can cause a change in pH and HCO<sub>3<\/sub><sup>-<\/sup>, i.e. acidosis and alkalosis.<\/li><li>All the independent variables must be known to calculate the dependent variables<\/li><\/ul>\n\n\n\n<p>Thus, acid-base disorders can be classified as:<\/p>\n\n\n\n<ul><li><strong>Respiratory:<\/strong>&nbsp;increased or decreased PaCO<sub>2<\/sub><\/li><li><strong>SID changes:<\/strong><ul><li>due to excess or deficit of water<\/li><li>due to excess or deficit of strong ions<\/li><\/ul><\/li><li><strong>A<sub>TOT<\/sub><\/strong>&nbsp;changes: excess or deficit of inorganic phosphate or albumin<\/li><\/ul>\n\n\n\n<p><strong>Advantages of the Stewart method:<\/strong><\/p>\n\n\n\n<ul><li>Quantitative mathematical explanation of acid-base disorders<\/li><li>A more scientific approach - applies the concepts of physical chemistry to traditional acid-base concepts<\/li><li>Accessible, logical framework for the design of resuscitation fluids<\/li><li>Attributes an appropriately low importance to HCO<sub>3<\/sub><\/li><\/ul>\n\n\n\n<p><strong>Disadvantages of the Steward method:<\/strong><\/p>\n\n\n\n<ul><li>Complex<\/li><li>Substantially different to the well-validated classical approach; thus, produces confusion<\/li><li>Numerous variables, each measured with a small error, are combined- thus amplifying the measurement error<\/li><li>Fails to incorporate the buffering contribution of haemoglobin<\/li><li>No evidence that this approach has any influence on mortality<\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Stewart&#8217;s physicochemical approach to acid-base analysi [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[13,14],"tags":[],"_links":{"self":[{"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts\/19041"}],"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=19041"}],"version-history":[{"count":1,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts\/19041\/revisions"}],"predecessor-version":[{"id":19042,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=\/wp\/v2\/posts\/19041\/revisions\/19042"}],"wp:attachment":[{"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=19041"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=19041"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/csccm.org.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=19041"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}