Blood gases: continuous in vivo recording of partial pressures by mass spectrography.

Gases were sampled directly from circulating blood through a membrane at the tip of an intravascular cannula that was connected to the analyzing section of a mass spectrometer. Partial gas pressures and membrane permeability determine gas flow into the spectrometer. Arterial carbon dioxide and oxygen pressures were simultaneously recorded in an anesthetized animal subjected to various respiratory maneuvers.