During normal respiration in an individual with healthy lungs, the body identifies the need to stimulate increased respirations by monitoring changes in the carbon dioxide (CO2) levels in the peripheral chemoreceptors. These changes are very minor and occur very early if the person is experiencing any hypoxia.
The hypoxic drive however, is a late homeostatic system designed to increase respiration rate and depth (tidal volume) when the body’s arterial oxygen levels (SaO2) decreases significantly. This is why patients who are somewhat dependent on an hypoxic drive to breath normally only saturate at around 90-92% oxygenation.
The hypoxic drive only accounts for a very minimal amount of the body’s desire to breath (approximately 10-15%) and generally, this is so low, that most people would literally become unconscious before their body’s hypoxic drive will trigger the need to increase tidal volume and rate of ventilation.
However, in patients who have chronic airway limitations (also known as chronic obstructive pulmonary disease), their body is continuously surviving on a much higher than normal blood CO2 level, and the body eventually “gives up” attempting to correct this diversion from normal homeostatic CO2 parameters within the peripheral chemoreceptors.
It should be noted however, that currently theories regarding the need for the hypoxic drive in patients who have had prollonged periods of high CO2, such as those with chronic respiratory diseases/ or disorders, under the headings of COPD and CAL are currently under review and there is some discourse on the topic amongst medical professionals and scientists alike.