Carbon dioxide like air, water and oxygen is essential for life, health and specifically, it holds the key to resolving asthma, cancer and many other chronic diseases. Carbon dioxide is an essential constituent of tissue fluids and as such should be maintained at an optimum level in the blood. The gas therefore is needed to supplement various anaesthetic and oxygenation mixtures for use under special conditions such as cardio-pulmonary by-pass surgery and the management of renal dialysis.
Summarizing, low cell oxygen levels due to 2 effects, constriction of arteries and arterioles (since CO2 is a most potent vasodilator) and the suppressed Bohr effect. There are actually many reasons for low oxygen, and even red blood cells have been reported to shrink and become stiffer under hypoxic conditions. Red blood cells also lose their optimal shapes under magnesium deficiency.
 Int J Hyperthermia. 2010; 26(3): 232–246. Hypoxia-Driven Immunosuppression: A new reason to use thermal therapy in the treatment of cancer?