Bonfils Laryngoscope - Technique, Contraindications, and Limitations

Introduction:

A difficult airway is considered a clinical situation in which a trained anesthesiologist has difficulties with upper airway facemask ventilation, tracheal intubation, or both. The difficult airway results from a complicated interaction between patient variables, the hospital setting, and the practitioner's expertise. It is a feared anesthetic situation because, if managed incorrectly, it might result in hypoxic brain damage or death. Mortality and brain damage have dropped considerably with the advent of advanced respiratory monitoring and new standards of care for patient monitoring and management of difficult airways.

What Is the Design of the Bonfils Retromolar Intubation Fiberscope?

• The Bonfils retromolar intubation fiberscope is a rigid, straight fiber-optic device with a 40-degree curved tip. It is 40 cm long and 5 mm in diameter on the outside (OD).

• The 40-degree angle allows for precisely targeted intubation. It contains a handle with an eyepiece attached at the proximal end; it may be used for direct viewing or can be connected to a camera and video monitor system.

• The stylet handle can be fitted with a light source or a tiny battery handle. The adult Bonfils contain a 1.2 mm working channel in the shaft that can be utilized for awake intubation using the "spray as you go" (local anesthetic) approach.

• The Bonfils was developed to be lightweight, sturdy, and movable. It is available in two additional sizes with a 2 mm or 3.5 mm OD for usage in youngsters.

What Are the Various Types of Direct Laryngoscope Blades?

The two most widely used direct laryngoscope blades are the Miller (straight) and the Macintosh Mac (curved). Direct laryngoscopy facilitates the visualization of the larynx and is often preferred during surgical procedures around the larynx, resuscitation, and general anesthesia.

How Is the Device Prepared?

• After silicon spray lubrication, the endotracheal tube (ETT) is inserted into the scope body and secured at the proximal end by a detachable ETT holder.

• The distal beveled tip of the ETT should be positioned with the distal end of the Bonfils fiberscope.

• The tube adapter enables continuous oxygen insufflation or pumping within the loaded ETT but outside the Bonfils shaft.

• Oxygen insufflation reduces the formation of a mist of the Bonfils distal lens and redistributes oral secretion away from the lens tip.

• In addition, an anti-fog solution applied to the lens enhances the image. The attachment may be rotated sometimes, so it is critical to ensure that the attached camera and video monitor system are appropriately fixed and oriented.

• Antisialagogue medicines and sedatives may be given to the individual during awake tracheal intubation.

• The patient is lying on his back with his head in a neutral posture. The operating table is set to the lowest position for convenience, or the operator may utilize a standing stool.

What Is the Intubation Technique?

• The retromolar oral insertion approach is suggested. It requires a tiny mouth opening and does not require the patient's head to be hyperextended.

• The left hand first executes a chin-lift by holding the lower jaw and tongue to access the laryngeal inlet.

• The scope is introduced from the right side of the patient's mouth, alongside the molars, and progresses below the epiglottis in the retromolar approach.

• To visualize the epiglottis, the distal end is moved. After that, the scope is gently moved into the glottic opening until tracheal rings are observed.

• When the Bonfils tip is in the desired position, the ETT may be pushed forward ("railroaded") into the trachea using moderate corkscrew motions after being released from the ETT holder.

• This approach should be avoided because the danger of tracheal damage increases when the tip of the Bonfils is advanced into the glottic opening.

• If the Bonfils tip is placed outside the trachea at the laryngeal opening before advancing the ETT, unintentional esophageal intubation or arytenoid damage may occur.

• The scope might be moved up to the midline until it reaches the epiglottis.

• The scope might be moved up to the midline until it reaches the epiglottis. If they maintain a midline approach, it is simple to locate the glottis.

• Direct laryngoscopy, rather than a chin-lift or jaw push, expands the retropharyngeal space before inserting the Bonfils.

• When the ETT tip crosses the vocal cords, the laryngoscope is removed, and the ETT is pushed into the trachea.

How Is the Device Cleaning Done?

• The Bonfils fiberscope is cleaned and disinfected after every use. It should be cleaned with a disinfectant (for example, quaternary ammonium compounds) to eliminate apparent spillage.

• The oxygen insufflation tube is also washed. The Bonfils are then entirely submerged in the disinfectant before being washed with water and dried.

• Machine cleaning and disinfection are alternative methods. Sterilization can be carried out using steam or chemicals.

What Are the Contraindications and Limitations of Bonfils?

• A mouth opening of at least 2 to 3 cm is required to allow for the easy placement of the Bonfils intubation endoscope and progress to the laryngeal inlet through the retromolar route.

• Blood or secretions in the upper airways limit indirect optical intubation devices because soiling the lens due to secretions will considerably impair vision.

• Secretions on the endoscope tip may obstruct vision to the extent that it blocks approximate placement under visual control.

• Suctioning the pharyngeal area before inserting the endoscope into the oral cavity may be beneficial.

• Obstructions in the glottis, epiglottis, and trachea will contraindicate the use of Bonfils' intubation endoscope, as they hinder the placement of the endotracheal tube.

Which Laryngoscope Is Used For Infants and Neonates?

The Miller straight laryngoscope blade is preferred to uncover the laryngeal inlet in infants since the epiglottis of infants is large and flexible. The commonly used straight blades are the Miller, Wis-Hipple, Wisconsin, and Wis-Foregger blades. Curved blades are recommended in older children.

A neonatal laryngoscope has been specifically designed to match the anatomy of neonates, thus making intubation efficient and straightforward. The Neonatal Resuscitation Program has recommended using size-0 Miller laryngoscope blades to suit premature neonates and suggests the size-00 Miller blade as optional. Generally, blades 00, and 0 are for premature babies, and 1 is for neonatal babies.

Conclusion:

Once mastered, the Bonfils retromolar intubation fiberscope is an excellent device for difficult intubations. Its adaptability enables it to be used in challenging settings such as unstable cervical spines, airway tumors, and awake intubations. It is also effective in normal airways when patients are at the possibility of sore throats or tooth damage. For any anesthesiologist who wants to master the treatment of difficult airways, a Bonfils fiberscope should have a place in their equipment.