Superimposed High-frequency Jet Ventilation Research Articles

A new prototype of an electronic jet-ventilator and its humidification system.

BACKGROUND: Adequate humidification in long-term jet ventilation is a critical aspect in terms of clinical safety. AIM: To assess a prototype of an electronic jet-ventilator and its humidification system. METHODS: Forty patients with respiratory insufficiency were randomly allocated to one of four groups. The criterion for inclusion in this study was respiratory insufficiency exhibiting a Murray score above 2. The four groups of patients were ventilated with three different respirators and four different humidification systems. Patients in groups A and B received superimposed high-frequency jet ventilation (SHFJV) by an electronic jet-ventilator either with (group A) or without (group B) an additional humidification system. Patients in group C received high-frequency percussive ventilation (HFPV) by a pneumatic high-frequency respirator, using a hot water humidifier for warming and moistening the inspiration gas. Patients in group D received conventional mechanical ventilation using a standard intensive care unit respirator with a standard humidification system. SHFJV and HFPV were used for a period of 100 h (4days). RESULTS: A significantly low inspiration gas temperature was noted in patients in group B, initially (27.2 +/- 2.5 degrees C) and after 2 days (28.0 +/- 1.6 degrees C) (P < 0.05). The percentage of relative humidity of the inspiration gas in patients in group B was also initially significantly low (69.8 +/- 4.1%; P < 0.05) but rose to an average of 98 +/- 2.8% after 2 h. The average percentage across all four groups amounted to 98 +/- 0.4% after 2 h. Inflammation of the tracheal mucosa was found in patients in group B and the mucosal injury score (MIS) was significantly higher than in all the other groups. Patients in groups A, C and D showed no severe evidence of airway damage, exhibiting adequate values of relative humidity and temperature of the inspired gas. CONCLUSION: The problems of humidification associated with jet ventilation can be fully prevented by using this new jet-ventilator. These data were sustained by nondeteriorating MIS values at the end of the 4-day study period in groups A, C and D.

Therapeutic effects of superimposed high-frequency jet-ventilation (SHFJV) in oleic acid induced porcine lung injury

Therapeutic effects of superimposed high-frequency jet-ventilation (SHFJV) in oleic acid induced porcine lung injury

Therapeutic effects of superimposed high-frequency jetventilation (SHFJV) in oleic acid induced porcine lung injury

Therapeutic effects of superimposed high-frequency jetventilation (SHFJV) in oleic acid induced porcine lung injury

SHFJV. Jet-adapter for application of superimposed high-frequency jet ventilation (SHFJV) via a tube in intensive care: a new technique

Despite advances and technical developments in the area of intensive care medicine it has not been possible to lower the mortality of patients with pulmonary insufficiency. Therefore, alternative ventilation strategies have been developed and applied. One of these ventilation techniques is superimposed high-frequency jet ventilation (SHFJV). For optimal application of SHFJV we designed a special jet-adapter. This jet-adapter made of plastic consists of a T-piece and four central, small-bore cannulas and can be connected to any commercially available endotracheal tube. Therefore, it does not require reintubation with an endotracheal jet tube when beginning SHFJV. The simultaneous high-frequency and low-frequency jet ventilation is performed over two jet-nozzles that have been designed according to optimal flow dynamic measurements. Two further cannulas are used for continuous airway pressure monitoring and humidification of the applied gases. A pre-warmed and humidified bias flow with exactly defined oxygen concentration is led through the cross-part of the T-piece for gas entrainment. Additionally, the cross-part contains a port that can be opened for endotracheal suctioning or bronchoscopy and makes disconnection of the jet adapter from the endotracheal tube for either purpose unnecessary. The jet adapter can be used: (1) to apply SHFJV; (2) to measure airway pressures continuously; (3) to humidify and warm inspired gases; (4) to administer medications or add nitrous oxide by the inspiratory route, enabling combination with new therapeutic possibilities in the management of patients with severe ARDS.

Improved oxygenation with superimposed high frequency jet ventilation at resonant frequency

Superimposed high-frequency jet-ventilation (SHFJV) is a new form of a combined high frequency (HF) jet ventilation technique in treatment of ARDS. Since the HF jet-stream improves oxygenation partially due to enhancement of the intra-pulmonary gas mixture [1] the question arises which frequency would be the most effective. Animal models and in vitro experiments demonstrate that the best results may be achieved with frequencies close to the resonant frequency (RF) of the lungs [1,2]. In this study we tried to find RF using SHFJV.

Nitric oxide application during superimposed high-frequency jet-ventilation in patients with ARDS

Inhaled nitric oxide (NO) reduces pulmonary hypertension in severe ARDS and improves arterial oxygenation by redistributing blood flow to areas with a normal ventilation/perfusion ratio [1]. As high peak inspiratory pressure (PIP) may contribute to pulmonary damage ventilatory strategies like high-frequency (HF) ventilation search to minimize PIP. This study was designed to evaluate the combined benefits of superimposed high-frequency jet-ventilation (SHFJV), a new HF jet-ventilation technique, with addition of inhalational NO.

Flow pattern of respiratory gases in superimposed high-frequency jet ventilation (SHFJV) with the jet laryngoscope

High-frequency ventilation techniques have been applied for a number of years for laryngeal surgery in order to ventilate patients without endotracheal tubes or catheters. A further development of high-frequency jet ventilation (HFJV) is the technique of superimposed HFJV (SHFJV), which was achieved by combining low- and high-frequency jet streams. Although good clinical results were observed, which have been published in the past, the clinical details of development of SHFJV have not been previously published. METHODS. In order to understand and study the mechanism of superimposition of a high-frequency jet stream, extensive experiments on a lung simulator at defined measuring points, which represented the operating field in microlaryngeal surgery and the trachea, were conducted prior to the clinical application of SHFJV. RESULTS. The measurements demonstrated that superposition of the two jet streams led to greater velocity during inspiration, and therefore produced an increase in tidal volume and entrainment of inspiratory gas. This demonstrates that it is possible to apply a HFJV technique in patients even with an open system. During expiration, the velocity of the low-frequency gas stream is decreased by the opposing flow of the high-frequency jet stream, leading to the buildup of positive end-expiratory pressure. The pulsations of the high-frequency jet stream induce continuous alveolar ventilation. The positioning of the jet nozzles in the jet laryngoscopy has the result that the velocities are already decreased at the tip of the laryngoscope and decrease further with distance from the nozzles. This prevents possible damage to the laryngeal mucosa.

Tubeless superimposed high frequency jet ventilation in high grade laryngeal stenoses

Massive stenosis of the larynx may present a potentially life-threatening situation for the patient, requiring immediate measures to ensure a patient's airway. The aim of this prospective study was to evaluate potential benefits of Superimposed High Frequency Jet Ventilation (SHFJV) in patients requiring microlaryngeal surgery due to massive stenosis of the larynx. 23 patients (age range 1.5 to 90 years) with laryngeal stenosis grade 2 and 3 according to the Cotton scale were ventilated using SHFJV. The duration of the SHFJV was 12 to 116 minutes. SHFJV was performed using a Bronchotron Respirator via a jet-laryngoscope. Arterial blood gases demonstrated paO2 between 71 and 295 mmHg and paCO2 of 28 to 81 mmHg. The mean FiO2 applied was 61.75 +/- 19.26. The airway pressure was measured at the tip of the jet-laryngoscope and was between 6 and 15 mmHg, and PEEP was 1 to 5 mmHg. In 13 patients a CO2 laser was utilised during surgery. In all patients SHFJV was performed without problems. Since the ventilation is delivered above any possible stenosis the danger of barotrauma is minimised. The surgeon obtains optimal visibility of the larynx and is not obstructed in the surgical procedure. SHFJV enables both the surgeon and the anesthetist to perform their respective duties and therefore increases the safety of the patient in the management of such a difficult problem as massive stenosis of the larynx.

Anesthesia in acute respiratory tract obstructions caused by high degree laryngeal and tracheobronchial stenoses

Stenotic process of the laryngeal and/or tracheobronchial system may lead to dyspnoea which can become life threatening. The object of our study was to determine whether sufficient gas exchange can be ensured in patients with a massive stenosis of the respiratory tract applying the Superimposed High-Frequency-Jet-Ventilation (SHFJV) via the jet laryngoscope. Further, it was to be determined whether SHFJV can be applied for insertion of endoluminal stents into the tracheo-bronchial system. SHFJV was applied using the Bronchotron-ventilator (capable of generating simultaneous low frequency and high frequency jets) and the laryngoscope, basically a modified endoscopy tube permitting simultaneous application of two jet modes. SHFJV was performed in 14 patients (including 4 children) suffering from massive laryngeal stenosis and in further 12 patients with stenosis of the tracheo-bronchial system. In all patients total intravenous anaesthesia was performed. In the patients with laryngeal stenosis the average paO2 was 117.5 +/- 43 mmHg, and the mean paCO2 47.3 +/- 11.6 mmHg. In the patients with stenosis of the tracheo-bronchial system the mean paO2 was 125 +/- 77 mmHg and the average paCO2 53.3 +/- 18 mmHg. The SHFJV technique presents the possibility to ventilate the patients continuously for surgical procedures even with massive stenosis of the respiratory tract. The application of SHFJV via the jet laryngoscope not only enables the anaesthesist to ventilate this group of patients but also helps the surgeon and therefore results in more safety for the patient.