The Use of Lancet LSA During Operations on the Larynx, Trachea, and Bronchus

This section has been prepared in accordance with the guidelines published by prof. D.G.Chireshkin, Head, Laboratory of Reconstructive Surgery of the Larynx and Trachea in Children (Children's City Hospital No. 2 named after I.V.Rusakov, in Moscow), and prof. Yu.M.Ovchinnikov, Head, Department of Ear, Nose, and Throat Diseases, I.M.Sechenov Moscow Medical Academy.

The vast majority of laser operations on the larynx, trachea, and bronchi require general anesthesia. In these cases the patient's position should his/her lying on the back with the head maximally thrown back. A bolster is put under the scapulae. The patient's occiput lies on the operating table. After giving the patient anesthesia, a direct supporting laryngoscopy is performed. To do so, a lusterless laryngoscope is employed. Microlaryngoscopy is generally made by a microscope connnected to the laser apparatus. As a rule, a high or moderate magnifying glass is used. The spots of pilot helium-neon laser radiation must be in the center of an operating field. In practice, one should use a pulsed laser with pulse durations of 0.1, 0.2, and 0.5 sec at an output power of 15 W, the pause between the pulses is 0.05-0.1 sec (see Table 6).

After taking all preliminary safety measures, the surgeon inserts a protective instrument into the larynx if required by the pattern of surgical intervention. The surgeon's other hand is put on the manipulator by which he runs a CO2 laser beam.

Under microscopic guidance he/she directs the laser beam with the manipulator, stepwise destroys tissues both in depth and over the surface. The carbonization marks appearing on the tissues due to laser radiation may be, if required, removed by a probe and cotton wool.

The substances occurring with thermal tissue destruction are eliminated from the zone to be operated on (the laryngopharynx, larynx, trachea) using different aspirators. If there is no need to apply protective instruments or if their handle is not completed with a appropriate channel, the surgeon or his/her assistant brings the tip of a dead-surface electric aspirator to the superior aperture of the larynx. During operations on the trachea and bronchus, it is convenient to make aspiration through the catheter introduced into the special channel of a laser bronchoscope.

The operation is generally bloodless as the CO2 laser beam well coagulates vessels, as large as 0.5 mm in diameter. If bleeding occurs, a hemostatic effect can be obtained by exposing the bleeding surface to a defocused laser beam with a spot diameter of 2.0 mm; the power density will be 320 W/cm2 at an output power of 10 W (see Table 4).

It is very important to inspect the lower surface of the vocal cords and all the subvocal fold parts properly, the latter may be removed with the laser beam that reflects from the speculum.

The techniques of endoscopic laser operations on the trachea and bronchi present some great difficulties and require the concerted actions of a surgeon, an assistant, and an anesthesiologist.

Before surgery, the bronchoscopic adapter is connected to the laser apparatus. One of the tubes of a laser bronchoscope with the delivered light source is coupled to the bronchoscopic adapter. By turning the set screws located on the face panel of the adapter, the pilot spots of a helium-neon laser are arranged in the center of the distal hole of a tube. Then the tube is connected to the electric suction machine and the gas-anesthetic mixture feeding system, and a plastic catheter is fixed to the bronchoscopic adapter for liquid nitrogen supply during laser radiation.

After anesthetizing the patient, upper or lower tracheobronchoscopy is made depending on the pattern of surgical intervention. The optical system of the bronchoscopic adapter offers a detailed view of the trachea and bronchi, evaluates the nature, site, and size of an abnormal formation. Then the bronchoscope is set so that the object to be removed is in its field of vision and the pilot radiation of a helium-neon laser is as far as possible directed into its center.

After hyperventilation of the lung, at the command of the surgeon and the anesthesiologist the assistant connects the liquid nitrogen supply and the anesthesiologist stops feeding a gas-anesthetic mixture or oxygen for a while. Only thereafter the surgeon switches on laser radiation by stepping on the foot pedal. As with operations on the laryngeal cavity, the pulsed laser at an output power of 15 W is indicated. The pulse duration may vary from 0.1 to 0.5 sec and the pulse pause is 0.05-0.2 sec depending on the pattern of an abnormal formation, its site, on the stage of surgical intervention (see Table 6).

In the presence of vocal cord nodules, a protective oval spade is put under the margin of the cord or slightly supinated using a coniform protector. The pulsed laser beam (pulse duration 0.1 sec, pause 0.1 sec) at an output power of 15 W is used to eliminate a nodule. If the nodule is located on the inferior medial surface of the vocal cord, the laser beam reflected from the speculum inserted into the true glottis should be applied.

Submucous cysts of the vocal cords are opened using the pulsed laser beam at 15 W, with a pulse duration of 0.1 sec, a pulse pause of 0.05 sec. Then the content of a cyst is aspirated and its outer surface is vaporized on several exposures to the laser operating in the same mode. The cystic bed is irradiated with a continuous defocused laser beam, 0.7 mm in diameter, at a power density of 2.6x103 W/cm2 (see Table 4).

In cysts of the outer ring and vestibular apparatus of the larynx, a pulsed laser at 20 W (pulse duration 0.1 sec, pulse pause 0.05 sec) is used to incise the wall of a cyst and its content is aspirated through the opening made. The diminished walls of a cyst are drawn out with the forceps available in the set of endolaryngeal microsurgical instruments and cut off at its base using a pulsed focused laser beam at 20 W (pulse duration 0.2 sec, pulse pause 0.05 sec). Then using the laser operating in the same mode, the cystic bed is vaporized. The operation is bloodless. The operation time is 20 to 40 min. Adverse reactions as hyperemia, slight fibrinous deposits and mild edema are observed within 3-5 days after surgery. Pain sensations are too insignificant. There are no respiratory or swallowing disorders. Vocal function rapidly recovers.

Laryngeal papillomatosis

In the presence of large conglomerates of papillomas, the latter are gripped with the forceps available in the set of endolaryngeal microsurgical instruments and cut off with a pulsed laser beam at 20 W (pulse duration 0.2 sec, pulse pause 0.05 sec). The bulk of papillomas is removed by this procedure. It is expedient to use a cone-shaped protector and a suction machine to eliminate papillomas from the inaccessible parts of the larynx. The vocal and vestibular cords are moved apart by means of the protector, thus making easier an access to the papillomas situated in the laryngeal ventricles. If the papillomas are present onto the interior medial surface of the vocal cords, the latter are slightly supinated with this tool; and if the papilloma is located onto the inferior surface of the vocal cords or beneath the anterior commissure, it is removed using the laser beam reflected from the speculum introduced into the subvocal space. Insignificant bleeding allows papillomas to be eliminated more thoroughly at laser surgery than at routine one.

While removing papillomas of the trachea and bronchus, one of the following two methods may be applied.

One method is that following tracheobrochoscopy and after defining the site of papillomatous vegetations, removal of the latter is started with the bronchi and distal portions of the trachea. This immediately facilitates the anesthesiologist's task to maintain adequate pulmonary ventilation. Moreover, the tube of a laser bronchoscope does not traumatize the coagulation film which forms at the site of the removed papillomas and plays a protective role. Exposure of papillomas to laser radiation is started with the areas medially located, i.e. layer-by-layer vaporization of papillomas is conducted.

The other method involves initial removal of papillomas from the proximal areas. To do this, the papillomatous conglomerates are almost entirely cut off with a laser beam and removed with forceps, which is virtually bloodless. Then the small remainders of papillomas and their sites on the tracheal and bronchial mucosas are vaporized. Some problems the anesthesiologist may have while maintaining the ventilation of the lung are compensated for much less surgical time.

Laryngeal granulomas are dissected at their base using a laser beam (power 20 W, pulsed mode, pulse duration 0.2 sec, pause 0.05 sec). If granulomatous remainders are detected at the site of dissection, they are vaporized with the laser operating in the same mode.

The similar methods are followed at surgery for laryngeal polyps and fibromas.

If the laryngeal and tracheal areas are entirely overgrown with scar tissue, a coniform protector which is inserted between the vocal cords is used and, as the scar tissue is vaporized, advanced along the formed canal just to the upper tracheostomic edge. In anterior commissural synechias, oval spatulas are employed, which are brought through the stenosis behind the scar. In patients previously undergone tracheostomy, the spatula is convenient to introduce through the stoma, but this does not rule out the application of wet gauze pads.

Different output powers from 15 to 20 W are used depending on the thickness of a scar, its site and extent. It is best to use the pulsed mode (the duration of a pulse is 0.1-0.2 sec), the duration between the pauses and hence the rate of their running are individually selected by the surgeon with the required energy density in mind (see Table 6). Operations to remove scars with a laser may be performed in one or two steps at an interval of weeks to months or in several steps. This depends on the extent and size of scars in different parts.

The introduction of protectors or dilators is not required in the postoperative period, which is a great advantage of laser surgery. In restenosis, success can be achieved in some patients after repeated surgery.

When the scars are located at the level of the vocal cords, the patients are not allowed to speak or sing in the postoperative period, then they should follow a sparing regimen during 14-18 days.

In abduction paralyses of the larynx, unilateral laser arytenoidectomy is performed by the following procedure: the laryngoscope is fixed so that the cartilage to be removed is entirely visible. The pulsed focused laser beam of the order of 10 W is directed to the area of projection of the corniculate cartilage. When freed from soft tissues, the cartilage is destroyed by laser radiation at the same power. The duration of a pulse is 0.5 sec, that of a pause is 0.05-0.1 sec. Then the arytenoid cartilage is freed from soft tissues and, along with the vocal process, is destroyed with a laser beam. The laser radiation power is 15 W, the pulse duration is 0.1 sec, the pause is 0.05 sec. The muscular process of the arytenoid cartilage is left.