[Separation of the airways: historical aspects].
Techniques to separate the airways to both lungs were employed in the laboratory by renowned physiologists like Pflüger and C. Bernard to study gas exchange. Pflüger's catheter, as used by Wolffberg in 1871 in the dog, essentially constituted an early example of endobronchial single lumen tube, and was to be the first airway separator introduced into man by Loewy and v. Schrötter in 1905 in experiments on circulation. As a variation of this device the carinal hook made ist appearance used by Hess in 1912 in rabbits. While the endobronchial catheters afforded airtight access to only one lung at a time for concomitantly studying ventilation in both lungs, a short tracheal cannula was combined with one introduced into the left main bronchus by Head in 1889, constituting as it were the prototype of double lumen (DL) tubes applicable to rabbits and turtles even. Werigo described 1892 a coaxial DL-tracheostomy cannula for dogs which construction principle was adopted in the first DL-bronchoscope used in man. In lung surgery during the 30s and 40s the ventilated lung was prevented from drowning by pus or secretions from the lung under surgery by sealing off ist main bronchus, either by endobronchial intubation or by a bronchial blocker inserted alongside the endotracheal tube. This principle gave rise to sophisticated devices, from the fixed combination of tube and blocker to the present-day tube housing a movable blocker. Remarkably, DL-intubation in its proper sense then was performed in bronchospirometry only. This technique was introduced by Jacobaeus upon suggestion of Liljestrand when dissatisfied with the restriction to sequential spirometry by customary bronchoscopic catheterization, relying on Frenckner's ingenious DL-bronchoscope. Rubber DL-tubes were developed by Gebauer 1939 and Zavod 1940 exclusively with bronchospirometry in mind, even E. Carlens primarily constructed his tube to improve this procedure. After its usage in over 100 bronchospirometries it was introduced for the first time in November 1949 for its familiar purpose: the resection of a tuberculous abscess in the right upper lobe. Once introduced into thoracic anaesthesia, the DL-principle so far fostered a wide variety of tube designs.