A mixed affective state, formerly known as a mixed-manic or mixed episode, has been defined as a state wherein features unique to both depression and  mania—such as episodes of despair, doubt, anguish, rage or homicidal ideation, suicidal ideation, splitting, racing thoughts, sensory overload, pressure of activity, and heightened irritability—occur either simultaneously or in very short succession. Previously, the diagnostic criteria for both a manic and depressive episode had to be met in a consistent and sustained fashion, with symptoms enduring for at least a week (or any duration if psychiatric hospitalization was required), thereby restricting the official acknowledgement of mixed affective states to only a minority of patients with bipolar I disorder. In current DSM-5 nomenclature, however, a "mixed episode" no longer stands as an episode of illness unto itself; rather, the symptomology specifier "with mixed features" can be applied to any major affective episode (manic, hypomanic, or depressive), meaning that they are now officially recognized in patients with, in addition to bipolar I disorder, bipolar II disorder and, by convention, major depressive disorder. A depressive mixed state in a patient, however, even in the absence of discrete periods of mania or hypomania, effectively rules out unipolar depression.
It was first proposed in 1965 that this respiratory insufficiency is most often due to injury of the lung rather than to the chest wall,  and a group led by J.K. Trinkle confirmed this hypothesis in 1975. Hence the modern treatment prioritizes the management of pulmonary contusion. Animal studies performed in the late 1960s and 1970s shed light on the pathophysiological processes involved in pulmonary contusion. Studies in the 1990s revealed a link between pulmonary contusion and persistent respiratory difficulty for years after the injury in people in whom the injury coexisted with flail chest. In the next decade studies demonstrated that function in contused lungs improves for years after the injury. References
External links

Chest Trauma - pulmonary contusion, trauma.org