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  <head>
    <title>008-02 Vascular impedance, microcirculatory failure, and pressure phenotypes</title>
    <ownerName>Integrated Medical Foundations</ownerName>
  </head>
  <body>
    <outline text="Vascular impedance and microcirculatory failure">
      <outline text="Impedance beyond steady resistance">
        <outline text="A pulsatile circulation, so resistance is incomplete"/>
        <outline text="Resistance links mean pressure to mean flow"/>
        <outline text="Impedance adds compliance, inertia, reflection, frequency"/>
        <outline text="Same mean resistance, different systolic load"/>
        <outline text="Arteriolar constriction raises mean load, redistributes flow"/>
        <outline text="Large-artery stiffness raises pulsatile load"/>
        <outline text="Drug classes differ in volume, rate and wave effects"/>
      </outline>
      <outline text="Wave reflection and pulse pressure">
        <outline text="Compliant arteries store ejected volume in systole"/>
        <outline text="Diastolic recoil maintains forward flow"/>
        <outline text="Lost compliance raises pulse-wave velocity"/>
        <outline text="Reflections return in late systole, not diastole"/>
        <outline text="Central systolic pressure and ventricular work rise"/>
        <outline text="Diastolic support of coronary perfusion may fall"/>
        <outline text="Wide pulse pressure: stiff arteries or large stroke volume"/>
        <outline text="Narrow pulse pressure: small stroke volume, or artefact"/>
        <outline text="Peripheral and central pulse pressure differ"/>
      </outline>
      <outline text="Perfusion pressure and autoregulation">
        <outline text="Inflow pressure minus downstream or surrounding pressure"/>
        <outline text="Cerebral: arterial against intracranial pressure"/>
        <outline text="Renal: pressures across glomerulus and capsule"/>
        <outline text="Coronary: aortic diastolic against ventricular pressure"/>
        <outline text="Arteriolar tone holds flow across a pressure range"/>
        <outline text="Chronic hypertension shifts the operating range"/>
        <outline text="Abrupt lowering can starve brain or kidney"/>
        <outline text="Severe hypertension exceeds the upper limit"/>
        <outline text="Carbon dioxide is a potent cerebral dilator"/>
        <outline text="Renal myogenic response and tubuloglomerular feedback"/>
        <outline text="Afferent and efferent tone set glomerular pressure"/>
      </outline>
      <outline text="Glycocalyx and fluid movement">
        <outline text="A thin, active endothelial surface layer"/>
        <outline text="Permeability, mechanosensing, coagulation, leukocyte traffic"/>
        <outline text="Subsurface protein sets the effective oncotic gradient"/>
        <outline text="Inflammation, hyperglycaemia, reperfusion and shear damage it"/>
        <outline text="Net filtration along much of the capillary"/>
        <outline text="Sustained venous-end reabsorption is the exception"/>
        <outline text="Lymphatics carry long-term balance"/>
      </outline>
      <outline text="Interstitial compliance and oedema">
        <outline text="Compliance sets how fast tissue pressure rises"/>
        <outline text="Low-compliance spaces: compartment and intracranial swelling"/>
        <outline text="Loose tissue holds volume before pressure climbs"/>
        <outline text="Danger depends on site as well as amount"/>
        <outline text="Oedema can coexist with intravascular depletion"/>
        <outline text="Protein-rich leak lowers effective circulating volume"/>
        <outline text="Low albumin acts with sodium, pressure and lymph capacity"/>
      </outline>
      <outline text="Venous function and stressed volume">
        <outline text="Unstressed volume fills without much pressure"/>
        <outline text="Stressed volume stretches vessels and drives return"/>
        <outline text="Venoconstriction raises mean systemic filling pressure"/>
        <outline text="Return falls as atrial pressure approaches filling pressure"/>
        <outline text="Very negative atrial pressure collapses thoracic veins"/>
        <outline text="Right-heart failure congests without excess volume"/>
        <outline text="Venous pressure impairs renal and hepatic drainage"/>
        <outline text="Incompetent valves give ambulatory venous hypertension"/>
        <outline text="Compression only after assessing arterial supply"/>
        <outline text="Spontaneous inspiration supports venous return"/>
        <outline text="Positive pressure cuts the return gradient"/>
        <outline text="Positive pressure may still unload the left ventricle"/>
      </outline>
      <outline text="Microcirculatory and distributive failure">
        <outline text="Restored pressure does not guarantee perfusion"/>
        <outline text="Heterogeneous flow: swelling, adhesion, microthrombi"/>
        <outline text="Shunting and stiff red cells limit extraction"/>
        <outline text="Distributive shock separates pressure from flow"/>
        <outline text="Output may be high while distribution fails"/>
        <outline text="Later depression, leak and lost reserve cut output"/>
        <outline text="Vasopressors restore pressure, not the syndrome"/>
        <outline text="Lactate rises by several routes, not oxygen alone"/>
        <outline text="A severity and trajectory marker, read in context"/>
      </outline>
      <outline text="Pressure phenotypes and measurement">
        <outline text="Clinic, home, day and night sample different states"/>
        <outline text="White-coat: high in clinic, lower outside"/>
        <outline text="Masked hypertension leaves risk undetected"/>
        <outline text="Absent nocturnal fall flags apnoea or kidney disease"/>
        <outline text="Orthostatic testing needs timing and symptom correlation"/>
        <outline text="Cuffs infer pressure from arterial oscillations"/>
        <outline text="Arrhythmia, tremor, stiffness and poor fit reduce accuracy"/>
        <outline text="Repeat extreme readings while assessing organ injury"/>
        <outline text="Ask what generates the pressure"/>
        <outline text="Trends under posture, exercise and treatment show reserve"/>
        <outline text="Mean pressure can rise while cool skin and oliguria persist"/>
        <outline text="Volume responsiveness is not an indication to give fluid"/>
      </outline>
    </outline>
  </body>
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