Intubation & Ventilation Scenario 12

      
   

 

      
      A 67 year old male with a history of hypertension is admitted to the ER with palpitations: ECG demonstrates a supraventricular tachycardia (probably atrial fibrillation). He is started on a diltiazem infusion, attached to a pulse oximeter and continuous ECG monitor. 30 minutes later, he becomes confused, his heart rate is 120, BP 80/62, and SpO2 is 81%. You do a blood gas and his CO2 is 32mmHg and PO2 is 45mmHg.        
      Failure to Oxygenate: diffusion defect

        
     

Solution

This patient has gone into acute pulmonary edema. This is confirmed on chest x-ray. The problem here is that the hydrostatic pressure in his pulmonary capillaries is so high that fluid is forced into the interstitial space and alveoli faster than it can be removed. There is thus a diffusion defect. Carbon dioxide diffuses better than O2, hence the hypocarbia in response to hypoxemia and hyperventilation.