Three classical papers in respiratory physiology by Christian Bohr (1855–1911) whose work is frequently cited but seldom read

Abstract

History has been kind to Christian Bohr (1855–1911). His name is attached eponymously to three different areas of respiratory physiology. The first is the Bohr dead space, which refers to the portion of the tidal volume that does not undergo gas exchange. The second is the increase in oxygen affinity of hemoglobin caused by the addition of carbon dioxide to the blood. This is known as the Bohr effect and is a very important feature of gas exchange, both in the lung and in peripheral tissues. Both of these contributions by Bohr are familiar to most students. Bohr’s third contribution refers to the calculation of the changes in the Po2 of blood as oxygen is loaded in the pulmonary capillary, the so-called Bohr integration. This contribution is less well known now, partly because of the advent of digital computing, but it was important in its day. The analysis is challenging because the very nonlinear shape of the oxygen dissociation curve means that the Po2 difference between the alveolar gas and the capillary blood, which is the driving pressure for diffusion, changes in a complicated way. All three papers are in German, and two of them are long and tedious to read. English translations are available, but few people read the papers, despite the fact that the first two articles are very frequently cited. In the present article, Bohr’s contributions are reviewed, and some parts of the articles that are particularly difficult to understand are clarified.