{"id":327,"date":"2016-07-26T12:53:50","date_gmt":"2016-07-26T12:53:50","guid":{"rendered":"http:\/\/emedsa.org.au\/CoreMed\/?p=327"},"modified":"2016-07-26T23:38:29","modified_gmt":"2016-07-26T23:38:29","slug":"shock","status":"publish","type":"post","link":"http:\/\/emedsa.org.au\/CoreMed\/2016\/07\/26\/shock\/","title":{"rendered":"Shock"},"content":{"rendered":"

Tweet<\/a><\/p>

Definition<\/strong><\/p>\n

Inadequate perfusion for metabolic requirements of\u00a0body tissue<\/p>\n

Therefore can involve decreased circulatory function, excessive tissue metabolic activity or both.<\/em><\/p>\n

It is one of the key issues to address in resuscitation<\/a><\/p>\n

Causes<\/strong><\/p>\n

Both a conceptual and clinical way of approaching the cause of circulatory dysfunction can be divided into<\/p>\n

    \n
  1. Hypovolaemic<\/strong> – decrease in circulating blood volume e.g. major bleeding<\/em><\/li>\n
  2. Distributive<\/strong> – vasodilation resulting relative decrease in blood volume e.g.\u00a0spinal\u00a0anaesthesia<\/em><\/li>\n
  3. Cardiogenic<\/strong> – reduced heart pump function e.g. myocardial infarction<\/em><\/li>\n
  4. Obstructive\u00a0<\/strong>– major obstruction <\/a>to circulatory flow e.g. saddle pulmonary embolus<\/em><\/li>\n<\/ol>\n

    Pathophysiology<\/strong><\/p>\n

    In response to the insult, circulatory system can compensate in several ways via activation of the baroceptor reflex and the renin-aldosterone-angiotensin system.<\/p>\n

    Initially<\/p>\n

      \n
    1. Vasoconstriction<\/li>\n
    2. Increased myocardial contractility and heart rate<\/li>\n<\/ol>\n

      Later<\/p>\n

        \n
      1. Sodium\/Water retention and increase of circulating volume<\/li>\n<\/ol>\n

        The response seen will vary according to which part of the compensatory system has been impaired e.g. loss of vasoconstriction in sepsis, inability to increase myocardial function after\u00a0cardiac\u00a0insult<\/em><\/p>\n

        Depending on the magnitude and duration<\/em> of the insult it is helpful to conceptualise three stages of shock<\/p>\n

          \n
        1. Compensated shock<\/strong> – homeostatic responses active and blood pressure\/perfusion maintained<\/li>\n
        2. Decompensated shock<\/strong> – homeostatic responses maximally activated and blood pressure\/perfusion falls<\/li>\n
        3. Irreversible shock<\/strong> – prolonged hypo-perfusion results in permanent damage to circulatory system such that \u00a0even correction inevitably results in death.<\/li>\n<\/ol>\n

          The important point is that falling\u00a0blood pressure<\/em>\u00a0is a late sign when shock is well established and should not<\/span> be the only trigger to take action<\/p>\n

          Clinical Manifestations<\/strong><\/p>\n