Intubation & Ventilation Scenario 10

      
   

 

      
      A 22 year old female is a passenger in the same accident: she is admitted with a liver laceration and four broken ribs on the right side. 48 hours after admission she becomes poorly responsive. Her PCO2 is 50mmHg and her PO2 is 50mmHg.        
     
Failure to oxygenate, primarily: due to ventilation perfusion mismatch (shunt)		        
     

 

Solution

This patient has a major ventilation-perfusion abnormality, probably due to a lung contusion in the tissue under the fractured ribs. Lung contusions act like pneumonia: airspace is filled with blood/exudates and there is loss of hypoxic pulmonary vasoconstriction, and thus blood shunts through this region and causes hypoxemia and hypercarbia.

The key to management is to optimize ventilation-perfusion matching, the patient should be placed “good side down”: dependent regions are both better perfused and better ventilated than non dependent ones (see figure below). This patient’s injury is on the right side, so she should be positioned on her left side.

 Ventilation-perfusion relationships