Commit d13d87c8 authored by Rachel Clipp's avatar Rachel Clipp
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Blood chemistry methodology updates.

parent b49c7e25
......@@ -183,7 +183,7 @@ If the partial pressure of oxygen in the blood rises to greater than 200 mmHg, t
### Brain Oxygen Deficit
The brain is unable to complete any significant anaerobic metabolism. Therefore, without oxygen in the brain, unconsciousness results within five to ten seconds, and permanent damage can occur within five to ten minutes @cite guyton2006medical. Additionally, irreversible damage can occur if the oxygen tension in the brain is too low for a prolonged period of time @cite dhawan2011neurointensive.
There are two events in the engine related to an oxygen deficit in the brain: Brain Oxygen Deficit and Critical Brain Oxygen Deficit. The engine triggers the brain oxygen deficit event when the partial pressure of oxygen in the brain drops below 21 mmHg. If the brain remains in this deficit state for 30 minutes, an irreversible state is triggered, and it will be impossible to regain homeostasis (akin to death). If the partial pressure of oxygen in the brain drops below 10 mmHg, the patient enters a critical brain oxygen deficit state, which causes an irreversible state after 10 minutes. If the critical deficit event is active, it is removed when the oxygen partial pressure increases above 12 mmHg, and only the less-critical deficit event will be active. Both deficit events are removed when the oxygen partial pressure returns above 25 mmHg, assuming the irreversible state was never reached. The threshold values are chosen based on empirical data reviewed in summary in @cite dhawan2011neurointensive, and from data presented in @cite purins2012brain and @cite doppenberg1998determination.
There are two events in the engine related to an oxygen deficit in the brain: Brain Oxygen Deficit and Critical Brain Oxygen Deficit. The engine triggers the brain oxygen deficit event when the partial pressure of oxygen in the brain drops below 19 mmHg. If the brain remains in this deficit state for 30 minutes, an irreversible state is triggered, and it will be impossible to regain homeostasis (akin to death). If the partial pressure of oxygen in the brain drops below 10 mmHg, the patient enters a critical brain oxygen deficit state, which causes an irreversible state after 10 minutes. If the critical deficit event is active, it is removed when the oxygen partial pressure increases above 12 mmHg, and only the less-critical deficit event will be active. Both deficit events are removed when the oxygen partial pressure returns above 25 mmHg, assuming the irreversible state was never reached. The threshold values are chosen based on empirical data reviewed in summary in @cite dhawan2011neurointensive, and from data presented in @cite purins2012brain and @cite doppenberg1998determination.
### Myocardium Oxygen Deficit
Blood flow through the coronary arteries provides required oxygen to the heart muscle. If the oxygen supply to the heart is limited through respiratory distress or some other condition, the demand for oxygen will cause dilation of the coronary arteries. By increasing the flow of blood to the heart muscle, the oxygen supply increases @cite guyton2006medical. This effect is not currently modeled in the engine, but the myocardium oxygen level is observed and an event is triggered when it becomes too low. In the future, the resistance to flow in the coronary arteries will be increased to represent blood vessel dilation, and the asystole rhythm change will be tied to the arterial partial pressure of oxygen.
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