Carbon dioxide hypoxia caused

Bronchiolar smooth muscle is sensitive to changes in carbon dioxide levels. Excess carbon dioxide causes bronchodilation and reduced carbon dioxide causes bronchoconstriction. Pulmonary vascular smooth muscle is sensitive to changes in oxygen levels excess oxygen causes vasodilation and insufficient oxygen (hypoxia) causes vasoconstriction. The changes in bronchiolar and vascular smooth muscle tone alter the amount of ventilation and perfusion in a lung unit to return the V/Q ratio to one. 

Acidosis occurs during cardiac arrest because of decreased blood flow and inadequate ventilation. Chest compressions generate only about 20% to 30% of normal cardiac output, leading to inadequate organ perfusion, tissue hypoxia, and metabolic acidosis. Furthermore, the lack of ventilation causes retention of carbon dioxide, leading to respiratory acidosis. The combined acidosis reduces myocardial contractility and may cause arrhythmias because of a lower fibrillation threshold. 

Lactate is a by-product of carbohydrate metabolism. It is burnt in the Krebs cycle normally but when there is an insufficiency of oxygen the normal production of carbon dioxide from glucose is not possible. Vasodilatation is a consequence of sepsis and produces abnormal blood flows, especially to the liver. So the liver does not metabolise glucose properly and lactate and acid are produced. Sepsis causes hypoxia and abnormal liver blood flow. The liver normally clears lactate. 

Carbon dioxide is a simple asphyxiant that is, it causes toxicity by displacing oxygen from the breathing atmosphere primarily in enclosed spaces and results in hypoxia. It has been postulated that the cause of death in breathing high concentration of carbon dioxide is due to carbon dioxide poisoning and not hypoxia based on a study performed in dogs. 

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