The Role of Probability. Basic Concepts of Probability. A probability is a number that reflects the chance or likelihood that a particular event will occur. Probabilities can be expressed as proportions that range from 0 to 1, and they can also be expressed as percentages ranging from 0% to 100%.
Thus, when people hypoventilate (i.e. causing an increase in CO2) this causes the pH in your blood to decrease, making it more acidic. (and when hyperventilation occurs, O2 is increased, which causes an increase in pH - making blood more basic).
During episodes of apnea though, where the body forcibly slows or shuts down breathing entirely in spurts, this can lead to dangerously high levels of carbon dioxide in the blood, and could lead to death in the most serious cases. Hypoventilation can be caused by numerous factors. These may be caused by natural obstructions in the airway, or resistances to sufficient airflow. These are commonly brought on by other medical conditions that result in lower airway obstruction, including emphysema, cystic fibrosis and bronchitis.