Alexander Aloy

Tubeless combined high-frequency jet ventilation for laryngotracheal laser surgery in paediatric anaesthesia.

Background: High‐frequency jet ventilation (HFJV) is an alternative ventilatory approach in airway surgery and for facilitating gas exchange in patients with pulmonary insufficiency. We have developed a new technique of combined HFJV utilising two superimposed jet streams. In this study we describe the application of tubeless supralaryngeal HFJV during laryngotracheal laser surgery in infants and children.

Tubeless Laryngotracheal Surgery in Infants and Children via Jet Ventilation Laryngoscope

We present the first use of tubeless superimposed combined high‐ and low‐frequency jet ventilation (SHFJV) with a jet laryngoscope in laryngotracheal surgery in infants and children. Twenty‐eight patients underwent 53 operative procedures. The average age of the patients was 7.3 years. The most common diagnoses were laryngeal papillomatosis and subglottic stenosis. The duration of jet ventilation averaged 33 min. The gas exchange was sufficient in each case. The advantages of SHFJV in the surgery of the laryngotracheal area in infants and children are optimal view at the larynx and trachea, maximum space for the handling, application of the laser without risks, no time limitation, suitability for stenosis, and neither anesthetic nor surgical complications.

Near-fatal paradoxical gas embolism during gynecological laparoscopy

Laparoscopy is an established procedure of minimally invasive surgery. Although risks and complications during laparoscopy are rare, complications arise from hemorrhage or intestinal perforation, and hemodynamic compromise may result from extensive pneumoperitoneum. Massive gas embolism is a potentially life threatening complication (1–5). We report an incident of severe paradoxical CO2 embolism verified by an intraoperative transesophageal echocardiogram.

Strömungsverhalten des Atemgases bei superponierter Hochfrequenz-Jet-Ventilation (SHFJV) über das Jet-Laryngoskop

ZusammenfassungIn der laryngealen Chirurgie werden, um eine endotracheale Intubation zu vermeiden, schon seit Jahren routinemäßig hochfrequente Beatmungsformen eingesetzt. Wir haben in einer Weiterentwicklung dieser Beatmungstechnik eine hochfrequente mit einer normofrequenten Jet-Ventilation kombiniert und konnten mit dieser superponierten Hochfrequenz Jet-Ventilation (SHFJV) sehr gute klinische Ergebnisse erzielen. Ziel unserer Gasgeschwindigkeitsmessungen am Lungensimulator an definierten Meßstellen, die dem mikrolaryngealen Operationsgebiet und der Trachea entsprechen, war es, einen Hinweis auf den Wirkungsmechanismus der SHFJV zu erhalten. Es zeigte sich, daß die Superposition der beiden Jetgasströme in der Inspiration eine höhere Geschwindigkeit und dadurch eine Vergrößerung des Tidalvolumens und des Entrainments bewirkt. So ist eine Beatmung auch bei Vorliegen eines völlig offenen Systems möglich. In der Exspirationsphase wird die Geschwindigkeit des normofrequenten Gasstroms durch den entgegengerichteten hochfrequenten Gasstrom verringert und so ein positiver endexspiratorischer Druck aufgebaut. Die Pulsationen des hochfrequenten Strahls bewirken eine permanente Belüftung der Alveolen. Die Anordnung der Düsen im Jet-Laryngoskop führt dazu, daß bereits an der Rohrspitze keine hohen Strahlgeschwindigkeiten mehr vorliegen und diese mit zunehmender Entfernung von den Düsen weiter abnehmen. Dadurch werden Schäden an der Larynxschleimhaut vermieden.AbstractHigh-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.

Superimposed jet ventilation via a special jet laryngoscope for endoluminal stent insertion in the tracheobronchial tree

Zusammenfassung. Die endoluminale Schienung mittels Silikonstents ist ein Verfahren zur sofortigen Wiederherstellung der Atemwege bei stenosierenden Prozessen des Tracheobronchialsystems. Die bisher dafür angewendeten Beatmungstechniken sind schwierig und mit Risiken behaftet, zumal die Patienten aufgrund der respiratorischen Insuffizienz in schlechter Verfassung sind. Wir wollten untersuchen, ob die Superponierte Hochfrequenz Jet-Ventilation (SHFJV) über das Jet-Laryngoskop, das von uns speziell für mikrolaryngeale Eingriffe entwickelt wurde, eine Anwendung zur tracheo-bronchialen Stentimplantation finden kann. Bei 12 Patienten mit akuter respiratorischer Insuffizienz (ASA 3 bis 5) aufgrund von Stenosen im Tracheobronchialsystem wurde eine Stentinsertion über das Jet-Laryngoskop unter SHFJV durchgeführt. Nach 5 Minuten wurde ein signifikanter Anstieg des paO2 (von 79,7±15 auf 228,4±45 mm Hg) bei zufriedenstellender CO2-Elimination (paCO2 zwischen 31,5±7,5 und 53,1±14 mm Hg) beobachtet. Die höheren CO2-Werte korrelieren mit der unmittelbaren Stentinsertion. Der Einsatz einer kombinierten nieder- und hochfrequenten Jet-Ventilation über das Jet-Laryngoskop ermöglicht die Applikation ausreichender Tidalvolumina und eine sichere Beatmung ohne Tuben oder Katheter. Das Jet-Laryngoskop bietet freie Einsicht auf das Operationsgebiet und gewährleistet eine weitgehend kontinuierliche Beatmung. Die einzige Apnoephase während der unmittelbaren Stentinsertion ist bisher durch kein Beatmungsverfahren zu vermeiden. Wir glauben, daß die Anwendung der SHFJV über das Jet-Laryngoskop für die Stentinsertion im Tracheobronchialsystem Vorteile sowohl für Anästhesisten als auch Chirurgen bietet.Abstract.Background. Stenotic processes of the tracheobronchial system may lead to dyspnoea that can become lift-threatening. To restore sufficient function of the blocked airway, a silicone stent can be inserted. The anaesthesia techniques used for this intervention so far have been complicated. The object of this study was to determine whether the superimposed high-frequency jet ventilation (SHFJV) via the jet laryngoscope originally designed for microlaryngeal surgery can be utilised for endoluminal stent insertion. Methods. In 12 patients with acute respiratory insufficiency (ASA 3 – 5) due to stenosis of the tracheobronchial system, an endoluminal silicone stent was inserted through the jet laryngoscope while the patient was ventilated using SHFJV. Results. A significant rise in paO2 readings prior to the jet ventilation and subsequent measurements was observed. The CO2 elimination was good (average paCO2 31.5±7.5 – 53.1±14 mm Hg). Variably high paCO2 readings during stent insertion were related to the respective surgical phases. At the end of the surgical manipulation, all patients had sufficient spontaneous ventilation. Conclusions. First clinical applications of the jet laryngoscope combined with superimposed jet ventilation for stent insertion demonstrated satisfactory results. Not only were the patients ventilated throughout the procedure, but CO2 elimination was also satisfactory. Superimposed jet ventilation provides a sufficient tidal volume with low ventilation pressures, and therefore oxygenation and CO2 elimination are unproblematic. SHFJV enables the anaesthetist to ventilate the patient nearly continuously with minimal phases of apnoea. The only apnoea phases, as with any other method, occur during surgical manipulation while inserting the stent and thus blocking the airway. We believe that the jet laryngoscope with SHFJV presents a distinct advantage for both anaesthetist and surgeon when inserting stents in the tracheobronchial system.

High-frequency ventilation for management of respiratory complications after trauma and major orthopaedic surgery

Patients with severe pulmonary insufficiency after trauma or major orthopaedic surgery challenge intensive care medicine with special problems. Impaired respiratory function due to shock, aspiration of gastric contents, infection. bronchopleural fistulae and massive transfusion necessitates increased ventilatory support, especially in patients with pre-existing severe skeletal deformity of the spine presenting with markedly increased chest wall stifkess and/or a highly restrictive lung pattern. Severe thoracic distortion is correlated with considerable reduction of vital capacity to below 25% ofnormal at Cobb angles between 30 and 60%. In patients developing adult respiratory distress syndrome, conventional mechanical respirator therapy has been associated with ventilator-induced lung injury arising fiom overdistension and damage to the remaining functional alveolar units [l]. Morphological changes of alveolar compartments with increased lung sfiess in these patients have been shown to be dismbuted non-homogeneously over the lungs, resulting in different airfilling conditions within particular lung segments. The remaining functional alveoli with preserved normal elasticity are predisposed to volume and barotrauma when airway pressures increase to improve impeded gas exchange. In patients with bronchopled fistulae the &action of tidal volume lost will be proportional to the airway pressure and inversely proportional to the compliance of the lungs. Delivering large tidal volumes requires high inspiratoq pressures and prolonged impiratov time and otien becomes ineffective in paaenB with respiratory fiilure. Consequently. intentional hypoventilation, reduction of peak inspintory pressures and extracorporal CO, removal have been introduced to limit alveolar overdistention. Alternative ventilation strategies have been developed and used to minimise airway pressure, to improve oxygenation at the lowest attainable F,o,. and to reduce mortality. These respiratory modalities include forms of highfiequency (HF) vendation, such as highfiequency jet-vendation (HFJV) and high-frequency percussive ventilation (HFPV). Here we consider the theoretical and technical aspects. ofhighfrequency ventilation, new techca l developments and report our clinical experience with HFJV and HFPV in patients with pulmonary insufficiency afier trauma or major orthopaedic surgery.

Transesophageal echocardiographic assessment of right heart hemodynamics during high-frequency jet ventilation

STUDY OBJECTIVE To evaluate right ventricular dimensions and function by echocardiography in anesthetized patients during superimposed high-frequency jet ventilation (HFJV). DESIGN Prospective clinical study. SETTING University hospital operating room. PATIENTS 20 ASA physical status I patients undergoing elective minor otorhinolaryngological surgery, and undergoing conventional mechanical ventilation with subsequent superimposed HFJV. INTERVENTIONS Two-dimensional transesophageal echocardiography with a 5-MHz multiplane transducer to determine right ventricular dimensions and function from a mid-esophageal view. Insertion of a radial artery catheter for monitoring blood pressure and blood gases. MEASUREMENTS AND MAIN RESULTS Heart rate, mean arterial blood pressure, and right ventricular end-diastolic and end-systolic volumes determined by echocardiography, stroke volume, and ejection fraction. Measurements were performed after 10 minutes of conventional positive pressure ventilation (control) and after 10 minutes of subsequent superimposed HFJV at similar peak and positive end-expiratory airway pressures. Right ventricular systolic and diastolic volumes, stroke volume, and ejection fraction did not reveal statistical significant differences after transition to HFJV. Interventricular septum did not show any abnormalities in motion. In contrast, interatrial septum demonstrated momentary mid-systolic bows toward the left atrium in 9 of 17 patients (53%) during conventional ventilation, but in 15 of 17 patients (88%) during jet ventilation. Heart rate and mean arterial blood pressure remained unchanged, but arterial oxygen tension values were higher and arterial carbon dioxide tension values lower during HFJV. CONCLUSION Transesophageal echocardiographic evaluation of right heart hemodynamics did not show any significant difference after transition of ventilation to superimposed HFJV applying similar airway pressures. Furthermore, superimposed HFJV was safe and effective, it improved oxygenation, and it facilitated carbon dioxide elimination.

Superponierte Hochfrequenz Jetventilation (SHFJV) unter Verwendung von NO

ZusammenfassungDa trotz ständiger Fortschritte in der Intensivmedizin die Mortalität von Patienten mit ARDS immer noch über 50% liegt, kommen in der letzten Zeit verstärkt alternative Therapieverfahren zur Anwendung. Wir haben aus pathophysiologischen Überlegungen heraus versucht, zwei alternative Verfahren, nämlich die Beatmung mit NO und die superponierte Hochfrequenz Jetventilation (SHFJV) miteinander zu kombinieren. In experimentellen Untersuchungen am Lungensimulator wurde zunächst nachgewiesen, daß unter SHFJV bei allen Geräteeinstellungen eine exakte Zudosierung von NO in jeder gewünschten Konzentration unter Verwendung des „Pulmonox“ möglich ist. Bei einem Sollwert von 20 ppm NO lagen die tatsächlich gemessenen Werte zwischen 18 und 22 ppm. Anschließend wurde das kombinierte Therapieverfahren erstmals klinisch bei einem Patienten mit präfinalem ARDS als ultima ratio eingesetzt. Es kam zu einer deutlichen Verbesserung der Oxygenierung (paO2stieg bei gleicher FIO2von 1,0 von 69,4 mmHg unter konventioneller Beatmung nach 30 min SHFJV mit 20 ppm NO auf 289,9 mm Hg an, die periphere Sauerstoffsättigung stieg von 88,3 auf 99,5% an). Die hämodynamischen Parameter zeigten keine Unterschiede zwischen den beiden Beatmungsformen. Der Patient starb trotz Verbesserung der pulmonalen Situation an einem therapieresistenten hämodynamischen Versagen. Es bleibt in weiteren Studien abzuklären, ob der Erfolg dieser Beatmungsstrategie reproduzierbar ist, und ob die Oxygenierung bei Kombination von SHFJV und NO besser als bei getrenntem Einsatz der beiden Maßnahmen.AbstractThe mortality of patients with acute respiratory distress syndrome (ARDS) is still above 50% despite continuous progress in intensive care medicine. Recent therapy regimens such as the extra corporeal life support (ECLS), permissive hypercarbia, high-frequency ventilation techniques and inhaled nitric oxide (NO) are being applied. All of the above techniques are aimed at different parts of the problems caused by ARDS. This study was designed to evaluate the possible additive benefits of superimposed high-frequency jet ventilation (SHFJV) and inhaled NO. Methods. In experiments on a lung simulator it was demonstrated that it is possible to administer exact amounts of NO using a computer-controlled system with a feedback loop (Pulmonox) using the SHFJV. Applying the therapeutic reference point of 20 ppm of NO, the deviation was ±3 ppm at this setting. Case report. After successfully concluding our experiments, this combined therapy concept was applied in a patient with terminal ARDS. Under CMV, paO2 was 69.4 mm Hg and the oxygen saturation 88.3% with a FIO2 of 1.0. Significant improvement was observed within 30 min after starting SHFJV with inhaled NO (paO2 282.9 mm Hg; oxygen saturation 99.5%). There were no differences observed in hemodynamic parameters between CMV and SHFJV. Although the pulmonary status of the patient improved, the patient died due to therapy-resistant hemodynamic failure. Conclusion. It will take further studies to judge whether the success of this new ventilation strategy is reproducible and if the improvement of the oxygenation is more pronounced when adding inhaled NO to SHFJV than when each technique is applied separately.

SHFJV : Jet-Adapter zur Durchführung der Superponierten Hochfrequenz Jet-Ventilation (SHFJV) über einen Tubus in der Intensivmedizin : Eine technische Neuerung

ZusammenfassungDie superponierte Hochfrequenz Jet-Ventilation (SHFJV) wurde als alternative Beatmungstechnik bei Patienten mit Lungenversagen eingesetzt. Um diese Beatmungsform optimal applizieren zu können, wurde ein spezieller Jet-Adapter entwickelt. Methoden: Dieser Jet-Adapter aus Kunststoff besteht aus einem T-Stück mit vier Kunststoffkanülen und kann an jeden handelsüblichen Endotrachealtubus konnektiert werden. Eine Umintubation auf einen speziellen Jet-Tubus vor dem Beginn der SHFJV ist unnötig. Die simultane hoch- und niederfrequente Beatmung erfolgt über zwei Düsen. Zwei weitere Kanülen dienen der kontinuierlichen Messung des Beatmungsdrucks und der Befeuchtung des Atemgases. Über den Querschenkel des T-Stücks wird ein Atemgasquerstrom geleitet. Eine zusätzliche, verschließbare Öffnung im Querschenkel des T-Stücks ermöglicht das Einführen eines Absaugkatheters oder eines Bronchoskops, so daß keine Diskonnektion vom Respirator erforderlich ist. Ergebnisse: Mit dem Jet-Adapter kann 1. die SHFJV angewendet werden, 2. der Beatmungsdruck kontinuierlich gemessen werden, 3. die Befeuchtung und Erwärmung der Atemgase durchgeführt und 4. Medikamente appliziert oder NO zugeleitet werden Schlußfolgerung: Der Jet-Adapter gewährleistet mit der SHFJV eine suffiziente Beatmung, die mit anderen therapeutischen Möglichkeiten kombiniert werden kann.AbstractDespite advances and technical developments in the area of intensive care medicine is 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. Methods: 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. Conclusion: 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.

Endoluminale Schienung (Stenting) bei Stenosen des Tracheobronchialsystems

ZusammenfassungDie endoluminale Schienung mittels Silikonstents ermöglicht es, bei stenotischen Prozessen des tracheobronchialen Systems, eine rasche Wiederherstellung der Atemwege zu erreichen. Damit kann entweder Zeit für eine spätere operative Sanierung gewonnen oder, im Falle von operativ nicht lösbaren Situationen, eine palliative Lösung erreicht werden. Stents sind für alle anatomischen Bereiche, von unmittelbar subglottisch bis in die Lappenbronchien hin, einsetzbar. Der wesentliche Vorteil liegt in der Vermeidung eines Tracheostomas und der guten Gewebsverträglichkeit, die auch eine langfristige Anwendung erlaubt. Berichtet wird über die technischen Aspekte des tracheobronchialen Stentings und die damit erzieiten Resultate bei 38 Patienten.SummaryEndoluminal insertion of siliconstents into the tracheobronchial system enables immediate restoration of stenotic airways. The device can be used temporarily until later operative treatment or it can be used as a definitive solution for otherwise irreparable situations. Stents are available for all anatomical regions from the subglottic area down to the lobar bronchi. The main advantage is the avoidance of a tracheostoma together with the good tolerance of the silicon material by the bronchial mucosa, allowing long term application. We report about the technical aspects of stent insertion and our experience and results in 38 patients.