See also
     Supplemental oxygen
     Mechanical ventilation

 

Oxygenation
     O2 problems, think shunt
     Adequate if     
          SpO2 >= 90%
          PaO2 >= 60 mmHg
     Appropriate if
          A-a (alveolar-arterial) gradient should normally be <10-20*
          = PAO2 (estimated) - PaO2 (measured)
          = FiO2 x 5 - PaO2 (measured)
          e.g. 20 x 5 - 54 = 46 <--gradient is too low
          *on room air normal gradient should be ~10
          *on 100% FiO2, gradient should be ~100
     Causes of a wide A-a gradient
          Shunt, 2 main types
               Intra-cardiac shunt
               Intra-pulmonary shunt
                    AV fistula
                    Perfused but not ventilated alveoli
                         Atelectasis
                         PTX
                         Pleural effusion
                         Hypoventilation from pain
                    Perfused but fluid-filled alveoli
                         PNA
                         Pulmonary edema
                         Aspiration

 

Ventilation
     Normal if
          PaCO2 is ~40
     pH balance
          Normal pH is 7.4, investigate derangements
     CO2 problems
          Increased CO2 production
               Increased metabolic activity
               Shivering
               Fever
               Thyrotoxicosis
               Seizures
               NMS
               Malignant hyperthermia
               Increased carbohydrate intake
          Decreased CO2 elimination
               Increased dead space
               Shallow breathing
               Apnea
               CO2 rebreathing

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The Compendium platform was created by David Kwinter, MD, CCFP(EM).