Why hyperventilation on pure oxygen should extend the breath holding time?
Hi, the partial pressure of O2 in air is 21%. In volumetric terms O2 constitutes one fifth the atmospheric air (the remaining is Nitrogen). This O2 in air keeps the arterial oxygen tension or pressure (PaO2), which is due to dissolved O2 in blood) about 100mmHg. This dissolved O2 is the readily available O2 for the human cells, In hyperventilation with pure O2 (also known as denitrogenation), the subject breathes 100% O2 not 21%, so the PaO2 may rise up to 600mmHg, so as u see the Oxygen available now is increased to 6 times & this is the cause of the prolonged breath holding time. Actually hyperventilation with 100% O2 makes a man withstand apnea for 7 minutes before developing hypoxia.Of course during this period of apnea CO2 will accumulate causing hypercarbia.
