8 vq ratio 08 vq pulmonaryartery lightred 5 lmin

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Unformatted text preview: fectiveness of gas exchange – “How well gases are swapped” • Ventilation – alveoli receives air at a normal rate of 4 L per minute • Perfusion – Capillaries supply blood to the alveoli at a rate of 5 L per minute Normal Ventilation and Normal Perfusion • Ventilation = 4L inspired air • Perfusion = 5L circulating blood • VQ ratio = 4:5 (0.8) V/Q ratio = 0.8 V/Q Pulmonary artery Light red 5 L/min blood flow in I ns p i r ed A i r V/Q – 4:5 4 L/min air in = 21% oxygen Pulmonary vein Dark red Inadequate Perfusion – Dead space • Ventilation is normal = 4L air • Perfusion is reduced or absent ­ 3L blood • Cause: embolism • VQ ratio HIGH 4:3 (1.33) 5 l/min Pulmonary artery I ns p i r ed A i r DEAD SPACE VENTILATION VENTILATION 4 l/min air in = 21% oxygen 3 l/min Pulmonary vein V/Q ratio = 4:3 = 1.33 HIGH Chief Complaint: compromised O2 Inadequate Ventilation (Shunt) • Ventilation is LOW = 2L air • Perfusion is normal 5L blood • VQ ratio 2:5 (0.4) LOW by ½ norm Inspir ed A ir SHUNT SHUNT 2 l/min air in Un­inflated alveoli. Cause of narrowing: asthma, allergic rxn, smokers (mucous), COPD 5 l/min Pulmonary artery V/Q ratio = 2:5 = 0.4 Pulmonary vein Inadequate Ventilation & Perfusion (Silent Unit) ”nothing going in or out” • Absence of Ventilation & • Absence of Perfusion They gon’ die Pulmonary artery Inspir ed A ir SILENT UNI...
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