Fig. 42.7  Transbronchial lung biopsy

and 11% in the next 300 patients [12]. Though this technique of lung biopsy was developed and utilized through the rigid bronchoscope, it is now standard of care to use a fexible bronchoscope for this sampling procedure. Transbronchial lung biopsies are standard of care in the diagnostic work-up of a variety of lung diseases and an inherent part of caring for lung transplant recipients [13, 14].

Flexible Transbronchial Needle

Aspiration (1978–)

The idea of transbronchial needle aspiration (TBNA) through the rigid bronchoscope was rst proposed by Eduardo Schieppati (1958). He proposed that this technique can be accomplished by passing a needle through a rigid bronchoscope to puncture the main carina and sample mediastinal lymph nodes [15]. This concept was furthered by the work of Oho and colleagues [16]. The rst report of sampling paratracheal tumors and masses was published in 1978 by Ko-Pen Wang

Fig. 42.8  Ko-Pen Wang—inventor of the fexible TBNA

(Fig. 42.8) [17]. He successfully accomplished this technique via fexible bronchoscopy. He then further re ned the technique by introducing a needle for histological specimen collection to help in diagnosing benign pathologies [18, 19]. Conventional TBNA (C-TBNA), which was commonly used in the 1980s and 1990s, has paved the way for the development of endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (EBUS-TBNA), which uses ultrasound technology via a probe at the apex of the scope to perform TBNA under direct visualization with ultrasonic images.

Laser Therapy (1981–)

The technique of delivering laser light with a wavelength of 1064 nm via a fexible quartz lament was reported by Lucien Toty and colleagues in 1981. They rst reported the use of this Nd:YAG laser in the airways through a rigid bronchoscope [20]. This laser beam had the

potential to coagulate or vaporize endobronchial lesions and abnormalities. The technique of using laser photoresection in patients with either malignant or benign lesions of the airway was further re ned by J.-F. Dumon who also played a vital role in developing the techniques of airway stenting. He is considered the Father of Interventional Pulmonology and he propagated the use of endobronchial use of laser to bronchoscopists worldwide.

Endobronchial Argon Plasma

Coagulation (APC) (1994–)

The year 1994 saw a newer mode of electrosurgical, noncontact, thermal ablation technique by using ionized argon gas (argon plasma). This pioneering modality was introduced by Grund and colleagues [21]. With this technique, 102 patients were treated endoscopically in 189 sessions with APC in the upper and lower gastrointestinal tracts as well as in the respiratory system. Lesions treated were mainly malignant and benign tumors, diffuse hemorrhages of various origins and sites, tissue overgrowth after stent implantation, tissue remnants after endoscopic resections, and the conditioning of stulas prior to brin sealing. APC was easy and effective in all cases via fexible bronchoscopy with minimal technical or other complications over standard electrocoagulation. Endobronchial APC currently offers the simplicity and low cost of an electrocoagulator with the noncontact approach of an Nd:YAG laser. The noncontact feature of APC allows rapid coagulation with minimal manipulation and mechanical trauma to the target tissue [22].

Endobronchial Stents (1990–)

Montgomery designed the rst T-tube with an external side limb made of silicone for tracheal stenosis [25]. J.-F. Dumon achieved a major breakthrough in airway stenting when he introduced a dedicated tracheobronchial prosthesis. This stent has a unique external surface with studs to preserve mucociliary action [26]. Since most pulmonologists in the United States are not trained in rigid bronchoscopy for stent placement, the utility of such stents has been limited. On the other hand, fexible bronchoscopy to place metallic stents is relatively easy but results in a signi cant amount of granulation tissue. This tissue reaction makes removal of these stents very challenging including possibility of airway laceration. Thus, their role is limited mainly to malignant processes, and they are the treatment of choice for bronchial dehiscence, especially after lung transplantation [27]. The ideal stent is one that is “easy to insert and remove, can be customized to t the dimensions and shape of a stricture, reestablishes luminal patency by resisting compressive forces but is suf ciently elastic to conform to airway contours without causing ischemia or erosion into adjacent structures, is not prone to migration, biocompatible, non irritating, and does not precipitate infection, promote granulation tissue, nor interferes with airway ciliary action necessary to clear secretions, and that is affordable” [28].

That ideal stent does not yet exist [28]. At present, highly specialized technology including three-dimensional printing with advanced radiographics is being employed to device stents speci c for each patient’s individual airway anatomy [29].

Bronchoscopy in Lung

Transplantation (1992–)

The very rst stent implantation was accomplished by Trendelenburg and Bond for the treatment of central airway strictures [23, 24]. This technique has made rapid progress since 1965.

Since 1986 when the rst lung transplant was performed, about 50,000 transplants have been performed in the United States for end-stage lung diseases. The most common complications post

lung transplant are: infection and rejection. Both these broad diagnostic categories cannot be narrowed upon without fexible bronchoscopy. Hence, the success of lung transplantation, however, cannot be imagined without the use of the fexible bronchoscope. This argument is supported by the study by Trulock and colleagues where they found a surprisingly high incidence of acute rejection in asymptomatic lung transplant recipients undergoing transbronchial biopsy [30]. The sensitivity of transbronchial lung biopsy was estimated at 72% for the diagnosis of acute rejection and 91% for the diagnosis of cytomegalovirus pneumonia. Surveillance bronchoscopy is performed in the rst year after transplant in many lung transplant programs because the incidence of acute rejection resulting in graft dysfunction is highest in this period. Some others perform fexible bronchoscopy with transbronchial biopsies only when clinically indicated (i.e., drop in lung function or new radiographic abnormalities). Nevertheless, both approaches aim to detect subclinical, clinical acute cellular rejection and antibody-mediated rejection. Flexible bronchoscopy is also crucial in the diagnosis and management of airway complications after lung transplantation [31].

Fig. 42.9  Heinrich Becker—promoter of the radial probe EBUS

Radial Probe Ultrasound (1992–)

(Fig. 42.9)

C-TBNA demonstrated the ability to access and sample mediastinal lymph nodes. However, the anatomy of the bronchial tree and associated vasculature make direct visualization of structures quite important, especially in the paratracheal regions and the hila. Ultrasound technology has made it possible to noninvasively assess most regions of the body. This concept led investigators to pursue real-time target visualization at the time of sampling. It was the pioneering work of Heinrich Becker that brought to fore the immense potential of applying ultrasound technology to the endobronchial region. This led to the development of EBUS or endobronchial ultrasound to guide sampling of mediastinal lymph nodes and parenchymal lesions [32]. Hurter and Hanrath rst reported the usefulness of radial probe EBUS (RP-EBUS) in 74 patients with central lesions and 26 patients with parenchymal lesions in consecutive procedures [33]. Although radial probe endobronchial ultrasound (RP-EBUS) continues to play a pivotal role in the diagnosis of peripheral pulmonary lesions, a major limitation of RP-EBUS, however, is that after localizing the lesion, sampling is still performed in a blind fashion. Investigators have however worked on other technologies to localize pulmonary masses and use real-time sampling in addition to RP-EBUS. This limitation has paved the way for the development of the convex probe EBUS (CP-EBUS) [34].

Convex Probe Endobronchial

Ultrasound (2004–)

Convex probe ultrasound was developed as an attempt to utilize real-time ultrasound technology to sample mediastinal lymph nodes and lung lesions. The distal end of the EBUS bronchoscope has a larger diameter than a fexible bronchoscope, with an angulated forward view at a 30-degree inclination (Fig. 42.10). This

a

b

Fig. 42.10  Convex probe EBUS. (a) Tip of the Endobronchial Ultrasound Bronchoscope. (b) Tip of the bronchoscope with infated balloon and a biopsy needle inserted through the working channel

Fig. 42.11  Kazuhiru Yasafuku

is necessary for imaging the lymph nodes and lung lesions and anchoring the scope to the airway while the needle comes out of a slightly

proximal opening. The eld of bronchoscopy imported the concept of linear probe ultrasound endoscopes from gastroenterology, after they were developed to sample paraesophageal lesions under real-time guidance. Pedersen and colleagues rst described the usefulness of linear EBUS in sampling mediastinal lesions in 1996 [35]. Kazuhiro Yasufuku and colleagues (Fig. 42.11) rst demonstrated the high diagnostic yield of the convex probe EBUS (CP-EBUS) in sampling mediastinal lesions [36]. Both studies reported a sensitivity of 96% and speci city of 100% for distinguishing between malignant and nonmalignant lesions [37]. Currently, CP-EBUS has become standard of care for diagnosis and staging of lung cancer as well as the diagnostic work-up of sarcoidosis and interstitial lung diseases [38, 39]. As shown in the granuloma trial, CP-EBUS-TBNA alone has been shown to have a high diagnostic yield for sarcoidosis. The yield is even higher when transbronchial lung biopsies are performed to complement it [40]. Thus, CP-EBUS has almost replaced surgical mediastinoscopy with a less invasive option.

Electromagnetic Navigation (2003–)

Although the problem of proximal lymph nodes and lung lesions has been solved by the development of RP-EBUS, accessing peripheral lung parenchymal lesions that are closer to the distal endobronchial tree still poses signi cant challenges. Electromagnetic navigation (EMN) is a technology that has been in continuous evolution since the late 1990s. This concept of navigating the bronchial tree or “global positioning system (GPS) of the lung” originated in Stephen Solomon’s animal laboratory [41]. The technique was re ned and applied for the rst time in humans by Yehuda Schwarz and colleagues in 2006 [42]. This technique involves a sensor and a computerintegrated magneticeld generator, which, when coupled with a three-­dimensional map created by computerized tomography, helps to visualize small peripheral nodules. This three-