Upper UTIs are infections of the kidneys. These are potentially life threatening, if bacteria move from the infected kidney into the blood. This condition is called sepsis. Sepsis can cause dangerously low blood pressures, shock, and death.
So whe you hold your breath, you stop getting oxygen in your lungs that go to your heart. The oxygen level in the blood drops, so your muscles need more oxygen, so the heart pumps faster. This is like running, your muscles need more oxygen so heart pumps faster
In short, the reason you can hold your breath longer when you hyperventilate isnât because of an increase in oxygen, but because of a decrease in CO2. Besides reducing the amount of CO2 in your system, hyperventilating actually reduces the amount of oxygen available to your muscles and organs.