Early Experiences by Others and Technical Improvements

 

 

Less than two years later, Kronschwitz (8) described the same technique for nasotracheal intubation as first communicated by Murphy (14), using a dedicated flexible fiberoptic laryngoscope (FFL, with a 90-degree angle of view, manufactured by the instrument maker Wolff, Knittlingen, Germany). The flexible insertion cord of this FFL was 36 cm long and had an external diameter of 5.5 mm, but did not incorporate a working channel and also had no levering mechanism for the distal end. Light was supplied by an external fiberoptic light source.

 

Kronschwitz recommended clearing of pharyngeal secretions by suctioning to obtain an unobstructed view, warming of the distal end of the FFL to prevent fogging of the optical lens, and lubrication of the insertion cord for easier passage through the tracheal tube (TT) before insertion of the FFL. He performed changes in head position and applied manual traction on the tongue when the pharyngeal space was restricted; together with these maneuvers and rotation of the TT when necessary, the entire unit, the TT with the FFL inside, was then advanced through the laryngeal aperture into a midtracheal position under direct view. He further recommended, that this unfamiliar endoscopic technique with a limited view for identification of anatomical structures should be first practiced on patients with normal airway anatomy before performance in difficult airway (DA) situations.

 

Publications During the Year 1972

 

Stiles and co-workers (21) reported their experiences of tracheal intubation in 100 patients with variable degrees of airway difficulties using a dedicated FFL, a prototype developed in cooperation with the Illinois Institute of Technology Research Institute (Chicago, Illinois, United States). The flexible insertion cord of this FFL was 45 cm long and had an external diameter of less than 6 mm, but did not incorporate a working channel. There was an angulation control level at the anterior side of the handle for bending the distal end upwards over a range of 180 degree. Light was supplied by an external fiberoptic light source.

 

Stiles and co-workers did not specify the route of access and the anesthetic technique applied; probably they performed naotracheal intubation under general anesthesia. The FFL, with the TT proximally at the base of the handle, was first advanced by manipulation of the distal end through the laryngeal aperture into the trachea and was then used as guide for the TT, later named the endoscope-first technique. They preferred spiral-wound TTs for protection of the delicate FFL and easier advancement of the TT into the trachea. In some patients, the TT obviously impinged on the epiglottis or laryngeal structures during advancement; they recommended rotation of the TT to overcome this problem. In four patients, tracheal intubation failed due to copious secretions obscuring the view; therefore, they advocated that a working channel for suctioning of secretions during the procedure should be integrated in any flexible endoscope dedicated for airway management (AM).

 

Two communications appeared on the first use of flexible bronchoscopy-assisted (FBA) nasotracheal intubation. Taylor and Towey (23) used a standard flexible fiberoptic bronchoscope (FFB) with a 65-degree angle of view (model BF-5B, manufactured by the Olympus Optical Company). The flexible insertion cord of this FFB was 56 cm long, had an external diameter of  5 mm, and incorporated a working channel. The distal end could be bended 130 degree upwards and 30 degree downwards by an angulation control level at the posterior side of the handle. The eyepiece contained a diopter adjustment ring to focuse and adapt it to the diopter of the operator. Light was supplied by an external fiberoptic light source.

 

For nasotracheal intubation in the awake patient, Taylor and Towey first applied topical anesthesia to the nasal and oropharyngeal mucosa using a spray. The FFB was introduced through the TT so that its bending section protruded beyond the tip of the TT. With this configuration, the FFB and the TT were then advanced until the laryngeal aperture came into view by manipulation of the distal end and in this position, a local anesthetic solution was instilled through the working channel, later refined and named the spray-as-you-go technique. Subsequently, the FFB together with the TT were directed through the laryngeal aperture and further advanced into the trachea.

 

Conyers and co-workers (3) had prior experiences with diagnostic bronchoscopy using a FFB and topical anesthesia, and used the same FFB as described by Taylor and Towey (23) for awake nasotracheal intubation. Following premedication with diazepam, achieving conscious sedation, they applied topical anesthesia to the nasal and oropharyngeal mucosa using a spray and to the tracheal mucosa by transtracheal instillation. They preferred the endoscope-first technique and emphasized the value of the working channel for suctioning of secretions, instillation of local anesthetic solutions, and collection of specimens. 

 

Publications During the Year 1973

 

Davis (5) described the use of a dedicated FFL with a 70 degree-angle of view, a prototype developed in cooperation with the American Optical Corporation (Southbridge, Massachusetts, United States), for awake nasotracheal intubation. The flexible insertion cord of this FFL was 35 cm long and had an external diameter of 5.5 mm, but did not incorporate a working channel. The distal end could be bended upwards and downwards in both directions over a range of 90 degree by a control knob at the right side of the handle. Light was supplied either by an external fiberoptic light source or by a snap-on battery handle.

 

Davis performed the endoscope-first technique in a patient with rheumatoid arthritis which he previously had to intubate using the retrograde technique for tracheal intubation, first described by Waters (24). He also mentioned the value of the FFL to check and estimate the TT position in relation to the tracheal bifurcation.

 

Tahir and co-workers (22) reported their techniques and experiences with standard FFBs (model BF-5B and smaller-sized models, manufactured by the Olympus Optical Company) for tracheal intubation and postoperative respiratory care. For uninterrupted inhalational anesthesia and/or ventilation, they used a Magill-type right-angle ellbow connector for the TT (10) with a self-made rubber diaphragm attached to the suction port, which prevented gas leakage around the FFB.

Tahir and co-workers performed nasotracheal intubation under light inhalational anesthesia and additional topical anesthesia. The TT, with the FFB inside the tube, was first advanced into the oropharynx; the FFB was then manipulated through the laryngeal aperure into the trachea, sometimes with the help of external laryngeal manipulation, and used as guide for the TT. For application of inhalational anesthesia and assisted or controlled ventilation during the procedure, they manually occluded the other nostril and the mouth. The same technique was used for orotracheal intubation together with a large-bore oropharyngeal airway of their own design serving as conduit for the TT and the FFB.

 

In mechanically ventilated patients, the TT adapter with the diaphragm provided uninterrupted ventilation during clearing of bronchial secretions. Copious secretions required repeated lavages for removal due to the limited diameter of the working channnel; in only few patients, rigid bronchoscopy was necessary. Even during the first days of mechanical ventilation, they frequently found mucosal lesions obviously induced by suction catheters and/or movements of the TT.
 

Publications During the Year 1974

 

The FFL developed by Davis became commercially available with a 60 degree-angle of view (manufactured by the renamed American Optical Machida Company at the same location), purchased at a fraction of the costs of standard FFBs. Raj and co-workers (16) reported their experiences with its use in 50 patients. The flexible insertion cord of this FFL was then 49 cm long and had an external diameter of 6.25 mm; the distal end could be bended upwards and downwards over a range of 120 degree.

 

In patients with a suspected DA, Raj and co-workers preferred awake nasotracheal intubation and ever used the tube-first technique. For orotracheal intubation, topical anesthesia was applied to the oropharyngeal and hypopharyngeal mucosa by a curved Jackson forceps and a cotton soaked with a standard local anesthetic solution, and to the tracheal mucosa by transtracheal instillation; when nasotracheal intubation was planned, they also applied topical anesthesia to the nasal mucosa by a cocaine spray, because of the additional vasoconstricting effect in order to prevent bleeding. Conscious sedation was obtained with fentanyl and dehydrobenzperidol. When performing orotracheal intubation, they frequently used a Macintosh laryngoscope for retraction of the tongue and opening of the oropharyngeal space. They emphasized the necessity of anticholinergic premedication in order to reduce secretions obscuring the view.

 

Furthermore, Raj and co-workers (17) reported their experiences with the use of this FFL for placement of Robertshaw double-lumen bronchial tubes, although the well lubricated endoscope just passed only through large-sized tubes. Under general anesthesia, the double-lumen tube was first placed into the trachea with conventional laryngoscopy. The FFL was then advanced through the bronchial lumen and maneuvered into the desired mainstem bronchus and used as a guide for the tube. Interestingly, they ventilated patients with compromised gas exchange with a Sanders injector system (18) attached to the proximal end of the tracheal lumen during the procedure. They also used this FFL for diagnosing accidental bronchial intubation of single-lumen TTs and for correct repositioning into the trachea.

 

Stiles (20) described the use of a standard adult FFB together with a guide wire for tracheal intubation in infants and small children, later named the two-stage technique. With the laryngeal aperture in view, a pliable guide wire was inserted into the working channel of the FFB (using the model BF-5B, manufactured by the Olympus Optical Company, or a similar model manufactured by the American Cystoscope Makers Incorporated) and passed it into the trachea. After removal of the FFB with the guide wire in place, a cardiac catheter with the proximal adapter removed was used as stiffening device and both together as guide for the TT. Between the two stages, the patients could be unimpededly ventilated via a face mask.

 

Barrett and co-workers (1) reported their experiences with standard FFBs (model BF-5B and BF-5B-2, manufactured by the Olympus Optical Company) for therapeutic bronchoscopy and airway evaluation in a large series of patients with acute respiratory insufficiency and failure. In patients with a tracheal or tracheostomy tube, they used a special bronchoscopy TT adapter, not specified in detail, for uninterrupted mechanical ventilation during the procedure; in spontaneously breathing patients without an artificial airway, bronchoscopy was performed after application of topical anesthesia via the nasal route.

Barrett and co-workers performed therapeutic bronchoscopy primarily for suctioning of retained copious secretions with or without lavage from the main bronchus or segmental bronchial segments inaccessible to blind suctioning, but also for foreign body removal after pulmonary aspiration of gastric contents on one occasion. After the procedure, improved airway patency was frequently reflected by clinical signs and roentgenographic resolution of atelectatic areas of the lung. They mentioned, that in spontaneously breathing patients, removal of retained secretions either delayed or prevented tracheal intubation and subsequent mechanical ventilation. The FFB was further used to check the TT position and to reposition displaced TTs. They organized and assembled an airway cart that contained all the necessarily required equipment and supplies for ready availability at the bedside.

 

Lindholm and co-workers (9) also reported their experiences with standard FFBs (model BF-5B2 and smaller-sized models, manufactured by the Olympus Optical Company) for therapeutic bronchosopy and airway evaluation in a large series of patients with acute respiratory insufficiency and failure, including those after weaning of long-term mechanical ventilation. They applied similar techniques as performed by Barrett and co-workers (1) and emphasized the versability of FFBs also for difficult tracheal intubation.
 

Publications During the Year 1975

 

Mulder and co-workers (12) reported their experiences with a standard FFB (model BF-5B, manufactured by the Olympus Optical Company) for awake tracheal intubation and airway evaluation in patients with a DA; they preferred the nasotracheal access using the endoscope-first technique as previously communicated (3). When topical anesthesia of laryngeal structures by a spray was impossible due to limited mouth opening, a bilateral superior laryngeal nerve block was performed percutaneously. They advocated that awake FBA tracheal intubation should become the procedure of choice for any DA situation. 

 

Davidson and co-workers (4) also reported their experiences with awake FBA tracheal intubation without specifying the model used in patients with a DA. They ever used the tube-first technique, and routinely applied additional topical anesthesia to laryngeal structures through the working channel. When only a small-sized nasotracheal tube could be passed down to the oropharynx, they inserted the FFB through the contralateral nostril and under direct endoscopic view, the nasotracheal tube was independently advanced into the trachea. For orotracheal intubation, they highly recommended the use of a bite block in order to avoid damage to the delicate FFB.

 
Moyers and Gregory (11) reported the use of a standard FFB for repositioning of a displaced TT during general anesthesia in a patient with a DA and deteriorating gas exchange undergoing a neurosurgical procedure in the right lateral position. The TT was considered to be displaced in the right intermediate bronchus and was withdrawn under direct endoscopic view above the bronchial bifurcation into a midtracheal position.

 

Further Developments

 

Many technical improvements followed with the development of various flexible fiberoptic endoscopes dedicated for AM (6). It was a long way for gaining experiences, particularly in patients with DAs, and a far longer way for introducing FBA techniques of tracheal intubation into standard clinical practice.

 

With time, the applications and indications for the use of FFBs have been substantially expanded (15). The manufacture of pediatric models of FFBs enabled us to use these endoscopes in the pediatric population for direct one-stage tracheal intubation and for placement and (re)positioning of double-lumen bronchial tubes. FFBs were soon also used for perioperative airway evaluation. 

 

 

References