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).
This may happen during the last few hours or even the last few days of your life. As death approaches, your breathing may become moist and congested. This has been called the death rattle.. Breathing changes commonly develop when you are weak and normal secretions in your airways and lungs become trapped.