Pulmonary compliance changes after experimental head injury.

Reduced static compliance has been reported in the lungs of experimental animals removed immediately after head injury. To relate these findings to clinical human experience, pulmonary dynamic compliance measurements were continuously made by clinically applicable methods in 18 monkeys subjected to severe head trauma. After a 2-hr control period, the monkeys were given a standard blow on the head and followed for 2 more hours. Two monkeys died immediately after trauma and two during the succeeding two hours. Pulmonary compliance significantly decreased in these animals only at time of death. No change in compliance was noted in animals which did not die during the 2 hours of observation after trauma were killed by further trauma. These animals did not demonstrate decreased compliance. The findings suggest that the mechanical characteristics of the lungs following head trauma in experimental animals can be measured by methods used clincally and may remain unaltered until immediately before the time of death.