The first ultrathin fiber-optic bronchoscope (FOB) was used through the working channel of a conventional bronchoscope. Developed by Tanaka et al. [1] in 1984, the model Olympus BF-1.8T was composed of fine optical glass fibers and had a tip diameter of 1.8 mm that could go up to 180 mm past the tip of a conventional fiber-optic bronchoscope. It had no working channel and could be bent passively only. Attachment to a special camera allowed for the first photographs of peripheral airways of 2 mm or less [2] and their first endoscopic classification [3]. By the same time, Prakash was using a regular pediatric fiber-optic bronchoscope (Olympus BF-3C4) with an external diameter of 3.5 mm to explore and sample with a cell brush the abnormalities present in more distal airways of adult patients [4]. In 1990 Tanaka et al. developed a second model of ultrathin with an outer diameter of 2.2 mm and distal tip that could be bent 120° upward and downward (Olympus BF-2.2T) [5]. Later in 1994 a new bronchoscope (Olympus BF-2.7T) was released by the same authors with a tip diameter of 2.7 mm and the novelty of incorporating a 0.8 mm working channel that allowed small airways sampling under direct vision with a cell brush (Olympus BC-0.7T) [6]. Since then, newer ultrathin fiber bronchoscopes and video bronchoscopes with working channels up to 1.2 mm have been developed as well as various types of brushes and biopsy forceps. Most recently, a new prototype of ultrathin hybrid bronchoscope with a working channel of 1.7 mm has been used that allows for radial probe EBUS performance [7]. A summary of the evolution of ultrathin bronchoscopes found in medical literature can be seen in Table 3.1. Pediatric bronchoscopes from other brands have also been used for exploring the peripheral airways of adult patients.

In essence, ultrathin bronchoscopes are thinner versions of the standard bronchoscopes. Although they can be used either in pediatric patients or in peripheral airways of adults, they are provided with longer insertion tubes than pediatric bronchoscopes.

Unlike standard flexible bronchoscopy which is divided into diagnostic and therapeutic categories, the use of ultrathin bronchoscopy is mainly diagnostic. As will be discussed later, its main limitation when sampling is the small working channel which limits both the suctioning capability and the use of instruments. In terms of contraindications, however, the same may apply.

Ultrathin bronchoscopy may be performed in a bronchoscopy suit with the patient awake or in mild sedation or in the operating room under general anesthesia and endotracheal intubation.

In Fig. 3.3 you can see the operating room with the necessary equipment for ultrathin bronchoscopy with virtual bronchoscopic navigation performance in a patient under general anesthesia.

The authors of the present text prefer performing ultrathin bronchoscopy under general anesthesia since it allows greater technical precision and better patient and operator comfort. Exploration of the peripheral airways can be a long procedure, and it is technically more challenging to manipulate the ultrathin through smaller bifurcations if the patient is not under a controlled respiration and in the absence of any movements or cough. Even more, having the patient under general anesthesia, it allows for a short controlled apnea application when sampling thus aiding in operator control of the instruments in the still peripheral lung. As in any case of general anesthesia, an anesthesiologist and qualified assistant as well as the necessary material for intravenous access, assisted ventilation, cardiorespiratory monitoring, and resuscitation equipment have to be available in the procedure room. While the diameter of the orotracheal tub is not relevant as ultrathin bronchoscope minimally compromises its lumen, its length needs sometimes to be shortened.