Pathophys Test 3

  1. What is the primary energy source for brain function? (p.1)
    • Glucose, which is converted to ATP (adenosine triphosphate).
    • ATP essential for neuronal metabolism and conductive activities.
  2. Review cerebral blood flow.
    What effect would increase or decrease in BP have on diameter of cerebral arteries? (p.6)
    • When systemic arterial pressure or ICP increases, arterioles vasoconstrict to safeguard brain from hyperemic flow state.
    • Decrease in BP --> vasodilation, protecting brain from subflow states and subsequent infarction.
  3. Review metabolic factors and pressure changes that affect brain’s ability to auto-regulate. (p.7)
    • Increased PaCO2
    • Potent dilator as brain attempts to remove products of cellular breakdown as efficiently as possible
    • PaCO2 from 20-80 mmHg
    • CBF (cerebral blood flow) = ½ if PaCO2 = ½
    • CBF = double if PaCO2 = double

    • Decreased PaO2
    • PaO2 <60 or O2 Sat <90 --> hyperemic flow state

    • Head injuries
    • 90% of moderate-to-severe head-injured patients have ischemic brain tissue on postmortem
    • Within ischemic tissue is contained massive quantities of waste; majority = vasodilatory agents

    • Intracranial bleeds – can result in loss of autoregulation (like SAH)
    • Blood contains many substances like calcium and free iron which are tolerated poorly in ventricular system and subarachnoid space of brain
  4. Review metabolic factors and pressure changes that affect brain’s ability to auto-regulate. (p.7)
    • Use of cerebral vasodilatory drugs
    • Halothane
    • Nitrous oxide
    • Histamines
    • Ketamines
    • Anti-hypertensives like Nipride

    Change in MAP

    Prolonged ICP > 35mmHg lasting longer than 20-30 minutes

    Changes in CPP
  5. Know how to calculate MAP. (p.8)
    Image Upload 2
  6. Know how to calculate CPP. (p.8)
    Image Upload 4
  7. What is CPP (cerebral perfusion pressure)? (p.8)
    • Estimate of adequacy of cerebral circulation
    • Normal = 50-150 mmHg
    • Average = 80-100 mmHg
    • CPP <50 = ischemia
    • CPP >150 = hyperemia
    • CPP <30 = incompatible with life --> neuronal hypoxia and cell death
Card Set
Pathophys Test 3
Neurodynamic 5-9