1,056
edits
Changes
Jump to navigation
Jump to search
Line 3:
Line 3: − + − + + + + + + Line 17:
Line 22: + + +
→Special Situations
=Calculating A-a gradient=
=Calculating A-a gradient=
Get an ABG. Then use the A-a gradient equation: PAO2 - PaO2 = ([Patm - PH2O] x FiO2 - [PaCO2/Q]) - PaO2 = ([Patm - 47] x FiO2 - [PaCO2/0.8]) - PaO2 = (150 - [PaCO2/0.8]) - PaO2, when at sea level with a patient breathing room air.
Get an ABG. Then use the alveolar gas equation:
A-a gradient increases with age, use equation: (Age+10)/4.
*PAO2 - PaO2
*PAO2 = ([Patm - PH2O] x FiO2 - [PaCO2/Q])
*PAO2 = ([Patm - 47] x FiO2 - [PaCO2/0.8])
*PAO2 = (150 - [PaCO2/0.8]) (when at sea level with a patient breathing room air)
Normal A-a gradient increases with age, use the equation: (Age+10)/4.
=Differential=
=Differential=
** Hypoventilation (increased PaCO2)
** Hypoventilation (increased PaCO2)
** Low SvO2 (low cardiac output, high O2 consumption)
** Low SvO2 (low cardiac output, high O2 consumption)
=Special Situations=
*CCBs can be a 'gas-fire on atelectasis' due to pulmonary vasodilation and disruption of V/Q matching leading to worsened shunt and hypoxemia