Table 1. Principle stores of oxygen in the body While breathing AIR While breathing 100% O2 In the lungs (FRC) 450ml 3000ml In the blood 850ml 950ml Dissolved or bound in tissues (FRC) 250ml 300ml Total 1550ml 4250ml
Causes….Mechanism…. D/D of Hypoxia/Hypoxemia…….. Non R E S P I R A T O R Y Does supplemental O2(↑FiO2)increase PaO2 substantially PaO2 SaO2 CaO2 P(A-a)O2 R-L shunt No ANAEMIA N N N NO CO / MethHb N N Possibly ventilation N NO Tissue (histo) N N N N NO
Causes….Mechanism…. D/D of Hypoxia/Hypoxemia…….. R E S P I R A T O R Y Does supplemental O2(↑FiO2)increase PaO2 substantially PaO2 SaO2 CaO2 P(A-a)O2 R-L shunt No (depends on magnitude of shunt) V-Q mismatch Yes Diffusion Barrier Yes ventilation N Yes PiO2 N Yes
LOW FLOW S. HIGH FLOW S. C.P.A.P. HYPERBAIC O2
Can provide 24%-50% oxygen by mixing room air with a precise amount of oxygen thereby delivering a precise FiO2. The size of the port and the oxygen liter flow determine the FiO2. The mask should be fitted to the patient as best as possible to prevent entrainment of room air around the mask which would alter the FiO2.