Release Of Hypoxic Vasoconstriction Research Articles

Understanding Hypoxic Drive and the Release of Hypoxic Vasoconstriction

Understanding the hypoxic drive and release of hypoxic vasoconstriction in the chronic obstructive pulmonary disease population can be somewhat confusing and misunderstood. Furthermore, the hypoxic drive theory is one in which there really is no scientific evidence to support and yet continues to prosper in every aspect of care in regard to the chronic lung patient, from prehospital all the way to intensive care unit and home care therapy. This subject review will hopefully enhance some understanding of what exactly goes on with these patients and the importance of providing oxygen when it is desperately needed.

Ventilation-perfusion relationships during halothane anaesthesia and mechanical ventilation. Effects of varying inspired oxygen concentration.

Ventilation-perfusion relationships (VA/Q), assessed by a multiple inert-gas elimination technique, were studied during halothane anaesthesia and mechanical ventilation at different inspiratory oxygen fractions (FIO2). All nine patients (mean age 65 years, five smokers) displayed unaltered VA/Q distributions with increasing FIO2 from a mean of 29% to 53%. A further increase in FIO2 to a mean of 85% caused an increase in true shunt (VA/Q = 0) from 7 to 10% of cardiac output (P less than 0.01), but no increase in "low" VA/Q (VA/Q less than 0.1). On the return to FIO2 of 29%, true shunt was reduced to the initial level. The findings may fit in with release of hypoxic vasoconstriction when FIO2 is increased to 85%, or the opening up of a certain population of shunt vessels.