Anoxia

Front 1

Definition of anoxia

Back 1

complete or partial disruption of oxygen supply to tissue

Front 2

Most common cause of anoxia

Back 2

cardiac arrest

Front 3

Other causes of anoxia or hypoxic encephalopathy

Back 3

-reduced arterial pressure secondary to lung disease
-reduced hemoglobin to carry oxygen secondary to anemia or blood loss
- biochem block of cerebral utillisation of oxygen secondary to cyanide poisoning

Front 4

Mitigators of extent of hypoxic damage

Back 4

-duration
-body temperature (hypothermia is protective)

Front 5

Specific neuroanatomy damaged by anoxia

Back 5

In order of effect
-hippocampus (loring)
-hippocampus/frontal cortex (lindsay & bone)
-parietal/occipital cortex
-basal ganglia/cerebellum
-brain stem
General guideline is grey more than white, and most vulnerable are watershed regions at end of vascular supply : hipposcampus, basal ganglia, cerebellum, occipital cortex, frontal regions

Front 6

Progression of deficits over time intervals

Back 6

-inattention
visual disturbance
-incoordination
-amnesia
-loss of consciousness
-brain stem signs
-flexion or extension to pain/death

Front 7

Damage to hippocampus in anoxia results in

Back 7

anterograde amnesia

Front 8

Visuspatial deficits secondary to anoxia include

Back 8

central vision disturbances
visual agnosia
cortical blindness

Front 9

Effects of oxygen deprivation on cognitive performance by partial pressure of arteria oxygen (PaO2)

Back 9

- 75% of normal - complex task performance altered
- 65% normal - memory is impaired
- 50% of normal - judgment altered and unconsciousness may occur
- 30-40% of normal death results

Front 10

Mechanism of neural damage in anoxia/hypoxia

Back 10

1. Lactic acidosis
2. Calcium influx and intracellular accumulation of calcium due to ionic pump failure
3. Neurotoxicity of excitatory amino acide NT - glutamate
4. formation of oxygen-free radicals following reperfusion/reoxygenation of damaged neuronal membranes