What condition would lead to an increased desaturation of hemoglobin?

The condition that leads to an increased desaturation of hemoglobin is carbon monoxide exposure. When carbon monoxide is inhaled, it binds to hemoglobin with a much higher affinity than oxygen, effectively preventing oxygen from binding to hemoglobin. As a result, even if there are high levels of oxygen in the environment, hemoglobin becomes saturated with carbon monoxide. This leads to a decrease in the amount of oxygen that is transported to the body's tissues, causing hypoxia despite what might seem like adequate respiratory oxygen levels. This physiological mechanism is why carbon monoxide poisoning is particularly dangerous; the desaturation of hemoglobin by carbon monoxide inhibits the delivery of essential oxygen throughout the body.