Evarts Ambrose Graham, empyema, and the dawn of clinical understanding of negative intrapleural pressure.

The concept of negative intrapleural pressure is fairly new. Although the phenomenon had already been described, Wirz provided the first definitive analysis of its significance to the mechanics of breathing in 1923. By contrast, empyema has been known since antiquity; from the time of Hippocrates, treatment has consisted of open drainage. Open drainage was often successful and did not result in pneumothorax, because most cases of empyema were associated with adhesions and thickened visceral pleura that prevented the lung from collapsing. The epidemic of group A streptococcal pneumonia in military camps in 1917-1918 was associated with the rapid and early accumulation of empyema fluid and was the catalyst for renewed study of empyema. Use of open drainage to manage this illness resulted in a high immediate mortality rate, probably because patients developed pneumothorax. The work of Evarts Graham and the Empyema Commission married physiological understanding of pleural mechanics with rational clinical treatment and paved the way for further advances in thoracic surgery.