JET VENTILATION LARYNGOLOGY PDF

The mode of ventilation depends on the type of surgery being undertaken . High-frequency jet ventilation gives an optimal surgical view but. approach to the airway and jet ventilation (JV) is a mutually convenient Ossoff RH: Laser safety in otolaryngology–head and neck surgery. ObjectiveTo describe our experience with superimposed high-frequency jet ventilation (SHFJV), JAMA Otolaryngology–Head & Neck Surgery .. This was partly achieved when various forms of jet ventilation were introduced for surgical .

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Technical diagram of the jet laryngoscope, with arrows indicating the flow of the jet stream. E indicates inspiration-expiration; P, pressure. With the longer operating times, the number of patients decreases because fewer patients required extensive surgery.

The arterial oxygen saturation SaO 2 of the patients with laryngeal stenosis Cotton III with hypoxemia with mist mask and 1. Demonstration of the positioned jet laryngoscope during ventilation and the free airways in a patient with squamous cell carcinoma of the right anterior vocal ventilatoon. Arch Otolaryngol Head Neck Surg. Copyright American Medical Association.

Ventilation was performed with an air-oxygen mixture, and intravenous agents were used for anesthesia.

High-frequency jet ventilation–a review of its role in laryngology.

Arterial blood gas values were analyzed. The average duration of the application of ventilation was 27 minutes, and the longest duration was minutes. No complications due to the ventilation technique were observed. Laser surgery was performed in patients. Even in patients at high risk because of pulmonary or cardiac disease, this technique can be applied safely.

In patients with stenosis, the ventilation is applied from above the stenosis, reducing the risk of barotrauma. The SHFJV can be used for tracheobronchial stent insertion, and laser can be used without any additional protective measures. An endotracheal tube creates an obstruction for endoscopic examination and during surgery of the larynx and, especially, the trachea. Stenosis of the laryngotracheal area leads to respiratory insufficiency and makes laryngloogy intubation impossible.

Developing a ventilation technique that does not obstruct the visibility of the operating field but ensures the adequate ventilation of patients has been the declared goal. This was partly achieved when various forms of jet ventilation were introduced for surgical procedures of the laryngeal region. A further step in achieving adequate ventilation without limiting visibility is the superimposed high-frequency jet ventilation SHFJVwhich was developed in by Aloy et al. Of the patients, were female, were male, and 40 were children ranging from neonate to 14 years of age.

The body weight ranged from 2. The patients’ diagnoses are listed in Table 1. One hundred eighty-eight patients laryngoloby In all patients, electrocardiography, arterial oxygen saturation SaO 2 using a pulse oximeter, and arterial blood pressure using an arterial catheter venhilation monitored simultaneously each datum by an automated device Merlin, model ; Hewlett-Packard Co, Waltham, Mass.

The ventilation pressure was measured continuously at the tip of the jet laryngoscope, and arterial blood gas analysis was performed every 5 minutes. The applied oxygen concentration was monitored by an anesthesia monitoring system Datex Devision Instrumentarium Corp; Helsinki, Finland.

The fraction of inspired oxygen FIO 2 values are those adjusted at the respirator, but the actual FIO 2 concentrations are lower because of the Venturi effect.

Intravenous anesthesia was used in all patients because SHFJV using the jet laryngoscope is an open system. As premedication, all adult patients received oral diazepam 0. Sufentanil and vecuronium were given as needed. After 2 minutes, the jet laryngoscope was inserted using a protection for the teeth. The tubing for both jet streams and the pressure monitor were connected to the jet laryngoscope, and SHFJV was started. At the end of the surgical procedure and after the patient regained protective reflexes, the jet laryngoscope was removed.

Mask ventilation was administered until the laryngolofy emerged from anesthesia. Neuromuscular blockade was reversed by administering neostigmine methylsulfate and atropine sulfate. The low-frequency jet stream provides 8 to 20 breaths per minute and serves primarily to remove carbon dioxide. The high-frequency jet stream, which provides to breaths per minute, causes a delay of the expiration of gas and prevents the lungs from being totally exhausted at the end of respiration.

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Because of this gas dynamic property, it is possible to achieve larger tidal volumes 3 than with single-frequency jet ventilation techniques 5 and to build up a positive end-expiratory pressure in an open system. The jet laryngoscope C. Reiner Corp, Vienna, Austriaa diagram of which is shown in Figure 1is a conical endoscopy tube used by otorhinolaryngology surgeons for laryngeal procedures that has been modified by Aloy et al.

The 2 jet nozzles are placed apart, one beside the other toward the distal end of the jet laryngoscope. The low-frequency jet stream goes through the distal cannula, and the high-frequency jet stream passes through the proximal cannula, maximizing the air entrainment Venturi effect. As a result of the design of the angle of insertion of the cannulas, the entering gas streams do not hit the opposite wall of the jet laryngoscope but are directed toward the center of the distal end of the jet laryngoscope.

A third cannula for continuous measurement of the ventilation pressure is inserted at the tip of the jet laryngoscope. Distinctive connectors prevent incorrect line connections to the jet respirator. The jet laryngoscope is available in 3 sizes for adults and 2 sizes for children. The other Laryngojet; Acutronic Corp, Jona-Rapperswil, Switzerland has electromagnetic valves and is controlled by a microcomputer. Both jet ventilators are capable of providing 2 separate jet streams with 2 different frequencies simultaneously, and both have an integrated alarm system with an inspiratory peak pressure limit.

If the adjusted pressure limits are exceeded, the gas supply is cut off and an alarm sounds. Ventilation is resumed once the inspiratory peak pressure drops below the adjusted threshold and the alarm has been reset.

Both ventilators work with an oxygen-air mixture, and both have integrated manometers for displaying the inspiratory pressure. Intravenous anesthetic is given, and air and oxygen are used for ventilation. The FIO 2 usually ranges between 0.

Due to the Venturi effect, the oxygen concentration in the operating area is diluted by room air and does not reach critical concentrations. In patients, satisfactory ventilation and oxygenation were achieved, with optimal conditions for the surgeons. Laser surgery was performed in patients, of whom 28 were children.

Complications due to ventilation with SHFJV, such as barotrauma, were not observed in any of the patients. The measured FIO 2 values are presented in Figure 2. The SaO 2determined by pulse oximetry, was between Except in the 3 patients mentioned earlier, the SaO 2 was always more than The mean values of the PaO 2 were All patients were hemodynamically stable at all times mean arterial pressure between The inspiratory pressures measured at the tip of the jet laryngoscope were 5.

Among the patients in whom ventilation was given by SHFJV, procedures were performed using laser. No complications related to the ventilation technique occurred.

Because of the high gas flow, smoke is removed instantaneously from the operating area, and devices for smoke suctioning are not necessary.

In 12 patients with severe hypoxemia due to extensive laryngeal stenosis, intubation was considered impossible.

Superimposed High-Frequency Jet Ventilation for Laryngeal and Tracheal Surgery

The SHFJV was applied, and all 12 patients received adequate ventilation Figure 3 during the entire surgical procedure. Postoperatively, all patients had sufficient spontaneous respiration. For endoscopic procedures of the larynx and the trachea, different jet ventilation techniques can be applied. Subglottic jet techniques applied through the larynx 67 or percutaneously through the trachea 8 with thin catheters provide safe ventilation during endolaryngeal surgery, if no major narrowing of the glottic space exists.

If, however, the patient has laryngeal or tracheal stenosis or is a child with stenotic alterations, eg, papillomatosis, these techniques are associated with increased respiratory risks, and in these patients, even narrow-caliber endolaryngeal tubes and catheters present a handicap to the surgical technique. Compared with all forms of single-frequency jet ventilation, the simultaneous application of 2 jet streams with different frequencies in SHFJV presents entirely new possibilities.

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The SHFJV leads to better inflation of the lungs than the single-frequency ventilation techniques and to better filling of the lungs during expiration. Movements of the vocal cords due to the low-frequency jet stream are diminished to a great extent by the high-frequency jet stream, which prevents a complete closure of the vocal cords, and only a slight movement of the peripheral parts of the vocal cords is observed.

If no movement at all is required, the low-frequency jet stream can be shut off for a short time.

Figure larhngology shows the positioned jet laryngoscope during SHFJV and the free airway in a patient with squamous cell carcinoma of the right anterior vocal cord. A misplacement of the jet nozzles is not possible because the jet nozzles are integrated into the jet laryngoscope.

The net gas flow at the vocal cords is close to 0, and therefore, blood and tissue particles are not blown into the lungs or environment.

In several patients with papillomatosis, endoscopic examinations at monthly intervals were performed after surgery using SHFJV, and in all patients the trachea was normal. That the patients with papillomatosis received ventilation using SHFJV had the further advantage that tracheotomy, which is a major lryngology in patients with laryngeal papillomatosis, 10 was not necessary.

The third cannula at the tip of the jet laryngoscope enables continuous inspiratory pressure monitoring. Because the gas pressures are already low in the plane of the operating vemtilation and further decrease toward the trachea, no adverse hemodynamic effects are observed when using the SHFJV. As with all jet ventilation techniques, an entrainment of room air occurs due to the Venturi effect of the gas stream leaving the nozzle.

This further enhances the tidal volume but also results ventilatuon a decreased applied oxygen concentration, as noted by the adjusted FIO 2 at the respirator. Passing through the jet nozzles, the gas stream undergoes changes. This pressure drop and the placement of the jet nozzles in the ventilafion part of the endoscope ensure that no high pressures occur in the distal part of the endoscopy tube. Therefore, the risk of damage to laryngoloogy mucosa of the larynx or the trachea due to the jet streams is unlikely.

Although the pressures are low millibarthe possibility of barotrauma cannot be eliminated entirely, but none of our patients experienced barotrauma due to SHFJV with the jet laryngoscope.

High-frequency jet ventilation–a review of its role in laryngology.

In patients with laryngeal stenosis Cotton II and III4 respiration might be impaired to such a degree that even surgical procedures using local anesthesia might not be possible. Attempts to improve oxygenation in these patients by applying high-frequency jet ventilation have been made using small translaryngeal or transtracheal catheters.

The gas insufflation is distal from the stenosis, and therefore, the technique carries a high risk of barotrauma. This is even higher if the catheter is placed through the residual lumen of the stenosis—further decreasing the lumen—or if the surgeon blocks the lumen by manipulating the instruments. Aloy et al 11 demonstrated in 23 patients with laryngeal stenosis Cotton II and III that, with proper adjustment of the respirator and using long inspiration times and a high working pressure, it is possible to overcome the high inspiratory resistance and to provide adequate ventilation.

The SHFJV is superior to the single-frequency jet ventilation techniques for use in obese patients and patients with pulmonary diseases. The SHFJV has even been used in patients with disease states—such as chronic obstructive pulmonary disease, restrictive pulmonary disease, coronary artery disease, and extreme obesity—that were regarded as relative or even absolute contraindications to single-frequency jet ventilation.

Because of the development of pediatric jet laryngoscopes, SHFJV is also applicable for laryngeal procedures in children.

If the jet laryngoscope is inserted correctly, the carina can be seen.