Device-Independent Witnesses of Entanglement Depth from Two-Body Correlators.

We consider the characterization of entanglement depth in a quantum many-body system from the device-independent perspective; that is, we aim at certifying how many particles are genuinely entangled without relying on assumptions on the system itself nor on the measurements performed. We obtain device-independent witnesses of entanglement depth (DIWEDs) using the Bell inequalities introduced in [J. Tura et al., Science 344, 1256 (2014)SCIEAS0036-807510.1126/science.1247715] and compute their k-producibility bounds. To this end, we exploit two complementary methods: first, a variational one, yielding a possibly optimal k-producible state; second, a certificate of optimality via a semidefinite program, based on a relaxation of the quantum marginal problem. Numerical results suggest a clear pattern on k-producible bounds for large system sizes, which we then tackle analytically in the thermodynamic limit. Contrary to existing DIWEDs, the ones we present here can be effectively measured by accessing only collective measurements and second moments thereof. These technical requirements are met in current experiments, which have already been performed in the context of detecting Bell correlations in quantum many-body systems of 5×10^{2}-5×10^{5} atoms.

Lowering bronchoaspiration rate in an acute stroke unit by means of a 2 volume/3 texture dysphagia screening test with pulsioximetry. / Reducción de la tasa de broncoaspiración con el test 2 volúmenes/3 texturas con pulsioximetría en una unidad de ictus.

INTRODUCTION: During acute stroke, 30% of all patients present dysphagia and 50% of that subgroup will experience bronchoaspiration. Our aim was to compare mortality and bronchoaspiration rates associated with the water test compared to those associated with a 2 volume/3 texture test controlled with pulse oximetry (2v/3t-P test) in our stroke unit. PATIENTS AND METHODS: Over a 5-year period, we performed a prospective analysis of all consecutive acute ischaemic stroke patients hospitalised in the Stroke Unit. Dysphagia was evaluated using the water test between 2008 and 2010 (group 0 or G0), and the 2v/3t-P test (group 1 or G1) between 2011 and 2012. We analysed demographic data, vascular risk factors, neurological deficit on the NIHSS, aetiological subtype according to TOAST criteria, clinical subtype according to the Oxfordshire classification, prevalence of dysphagia, percentage of patients with bronchoaspiration, and mortality. RESULTS: We examined 418 patients with acute stroke (G0=275, G1=143). There were significant differences between the 2 groups regarding the percentage of patients with TACI (17% in G0 vs. 29% in G1, P=.005) and median NIHSS score (4 points in G0 vs. 7 points in G1, P=.003). Since adopting the new swallowing test, we detected a non-significant increase in the percentage of dysphagia (22% in G0 vs. 25% in G1, P=.4), lower mortality (1.7% in G0 vs. 0.7% in G1, P=.3) and a significant decrease in the bronchoaspiration rate (6.2% in G0 vs. 2.1% in G1, P=.05). CONCLUSIONS: Compared to the water test used for dysphagia screening, the new 2v/3t-P test lowered bronchoaspiration rates in acute stroke patients.

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.

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.

Superimposed high-frequency jet ventilation for laryngeal and tracheal surgery.

OBJECTIVE: To describe our experience with superimposed high-frequency jet ventilation (SHFJV), which does not require any endotracheal tubes or catheters, for performing laryngeal and tracheal surgery. DESIGN: A case series of 500 patients. SETTING: A university medical center. PATIENTS: Four hundred sixty adult patients and 40 children in a consecutive sample who required laryngeal or tracheal surgery under SHFJV. INTERVENTIONS: The SHFJV uses 2 jet streams with different frequencies simultaneously and is applied using a jet laryngoscope. Ventilation was performed with an air-oxygen mixture, and intravenous agents were used for anesthesia. Arterial blood gas values were analyzed. MAIN OUTCOME MEASURES: Reported values of oxygenation and ventilation during the application of SHFJV and laryngotracheal surgery. RESULTS: In 497 patients, adequate oxygenation with a mean +/- SD PaO2 of 91.8 +/- 22.9 mm Hg and ventilation with a PaCO2 of 29.7 +/- 5.5 mm Hg were achieved using SHFJV. The average duration of the application of ventilation was 27 minutes, and the longest duration was 118 minutes. No complications due to the ventilation technique were observed. Laser surgery was performed in 150 patients. CONCLUSIONS: The use of SHFJV in combination with the jet laryngoscope provides patients with sufficient ventilation during laryngotracheal surgery. 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.

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.

Reducción de la tasa de broncoaspiración con el test 2 volúmenes/3 texturas con pulsioximetría en una unidad de ictus / Lowering bronchoaspiration rate in an acute stroke unit by means of a 2 volume/3 texture dysphagia screening test with pulsioximetry

Introducción: En la fase aguda del ictus el 30% de los pacientes presentan disfagia, y de ellos, el 50% experimentarán broncoaspiración. Nuestro objetivo fue evaluar los resultados de mortalidad y broncoaspiración del test del agua comparado con el test 2 volúmenes/3 texturas controlado con pulsioximetría (2v/3t-P) en una unidad de ictus. Pacientes y métodos: Durante 5 años se analizaron de forma prospectiva y consecutiva todos los pacientes con infarto cerebral en la Unidad de Ictus. Del año 2008 al 2010 se utilizó el test del agua (grupo 0 o G0), y del 2011 al 2012, el test 2v/3t-P (grupo 1 o G1). Se recogieron las siguientes variables: demográficas, factores de riesgo vascular, gravedad neurológica con la escala NIHSS, subtipo etiológico según criterios TOAST, subtipo clínico según la clasificación Oxfordshire, prevalencia de disfagia, broncoaspiración y exitus. Resultados: Se analizaron 418 pacientes con infarto cerebral agudo (G0 = 275, G1 = 143). Se detectaron diferencias significativas entre ambos grupos en el porcentaje de pacientes con TACI (17% en G0 vs. 29% en G1, p = 0,005) y en la mediana de NIHSS (4 puntos en G0 vs. 7 puntos en G1, p = 0,003). Con el test 2v/3t-P se detectó un aumento no significativo en el porcentaje de disfagia (22% en G0 vs. 25% en G1, p = 0,4), una menor tasa de mortalidad (1,7% en G0 vs. 0,7% en G1, p = 0,3) y una reducción significativa de broncoaspiración (6,2% en G0 vs. 2,1% en G1, p = 0,05). Conclusiones: El nuevo test 2v/3t-P, comparado con el test del agua, mejoró significativamente los resultados de broncoaspiración en los pacientes con infarto cerebral agudo

Introduction: During acute stroke, 30% of all patients present dysphagia and 50% of that subgroup will experience bronchoaspiration. Our aim was to compare mortality and bronchoaspiration rates associated with the water test compared to those associated with a 2 volume/3 texture test controlled with pulse oximetry (2v/3t-P test) in our stroke unit. Patients and methods. Over a 5-year period, we performed a prospective analysis of all consecutive acute ischaemic stroke patients hospitalised in the Stroke Unit. Dysphagia was evaluated using the water test between 2008 and 2010 (group 0 or G0), and the 2v/3t-P test (group 1 or G1) between 2011 and 2012. We analysed demographic data, vascular risk factors, neurological deficit on the NIHSS, aetiological subtype according to TOAST criteria, clinical subtype according to the Oxfordshire classification, prevalence of dysphagia, percentage of patients with bronchoaspiration, and mortality. Results: We examined 418 patients with acute stroke (G0 = 275, G1 = 143). There were significant differences between the 2 groups regarding the percentage of patients with TACI (17% in G0 vs. 29% in G1, P = .005) and median NIHSS score (4 points in G0 vs. 7 points in G1, P = .003). Since adopting the new swallowing test, we detected a non-significant increase in the percentage of dysphagia (22% in G0 vs. 25% in G1, P = .4), lower mortality (1.7% in G0 vs. 0.7% in G1, P = .3) and a significant decrease in the bronchoaspiration rate (6.2% in G0 vs. 2.1% in G1, P = .05). Conclusions: Compared to the water test used for dysphagia screening, the new 2v/3t-P test lowered bronchoaspiration rates in acute stroke patients

Superimposed high-frequency jet ventilation (SHFJV) for endoscopic laryngotracheal surgery in more than 1500 patients.

BACKGROUND: Superimposed high-frequency jet ventilation (SHFJV), which does not require any tracheal tubes or catheters, was developed specifically for use in laryngotracheal surgery. SHFJV uses two jet streams with different frequencies simultaneously and is applied in the supraglottic space using a jet laryngoscope and jet ventilator. METHODS: Between 1990 and 2004, SHFJV was studied in 1515 consecutive patients (including 158 children requiring laryngotracheal surgery) prospectively. Ventilation was performed with an air/oxygen mixture and anaesthesia was administered i.v. RESULTS: Adequate oxygenation and ventilation was achieved in 1512 patients. Arterial blood gas analyses (BGA) were performed between 1990 and 1994; thereafter BGA was only performed in patients with high-grade stenosis of the larynx/trachea or high-risk patients [n=623, mean Pa(O(2)) 133.8 (39.4) mm Hg and mean Pa(CO(2)) 42.3 (10.1) mm Hg]. There were no significant changes in Pa(O(2)) or Pa(CO(2)) during the entire period of SHFJV. No complications secondary to the ventilation technique were observed; in particular, no barotrauma occurred. Three patients required tracheal intubation. SHFJV was also successfully used for laser surgery (n=312). It proved to be a safe mode of ventilation without any complications such as airway fire, major haemorrhage, or aspiration of debris. CONCLUSION: SHFJV is an advanced ventilation mode playing a pivotal role in the (open) ventilatory support/ventilation of patients with laryngotracheal stenosis. It is particularly indicated in cases of severe stenosis and offers optimal conditions for laryngotracheal surgery, including laser surgery and stent implantation techniques.

Supraglottic combined frequency jet ventilation versus subglottic monofrequent jet ventilation in patients undergoing microlaryngeal surgery.

UNLABELLED: We compared the efficacy of gas exchange during supraglottic combined-frequency jet ventilation via a jet ventilation laryngoscope and during monofrequent jet ventilation via the Mon-Jet catheter (Xomed, Jacksonville, FL). Twenty-three anesthetized (propofol, fentanyl, vecuronium) patients undergoing microlaryngeal surgery were prospectively studied and randomly assigned to one of two groups. The patients' lungs were ventilated with combined-frequency jet ventilation (10 min, 15 and 600 breaths/min, inspiration/expiration time ratio = 1, driving pressure 750-1500 mm Hg), monofrequent (low-frequency group: 15 breaths/min; high-frequency group: 600 breaths/min) jet ventilation (20 min), and again combined-frequency jet ventilation (15 min). PaO(2), PaCO(2), and the inspiratory oxygen fraction (FIO(2)) were measured. Wilcoxon's signed rank test was applied. During monofrequent jet ventilation, PaCO(2) increased and the PaO(2)/FIO(2) decreased significantly (P < 0.05) as compared with combined-frequency jet ventilation (low-frequency group: PaCO(2) from 39.4 +/- 3.3 to 50. 8 +/- 8.0 mm Hg, PaO(2)/FIO(2) from 306 +/- 100 to 225 +/- 94 mm Hg; high-frequency group: PaCO(2) from 36.7 +/- 7.2 to 60.3 +/- 6.1 mm Hg, PaO(2)/FIO(2) from 429 +/- 87 to 190 +/- 51 mm Hg; mean +/- SD). After switching back to combined-frequency jet ventilation, PaCO(2) decreased and PaO(2)/FIO(2) increased to baseline levels. We conclude that gas exchange during microlaryngeal surgery can be more easily maintained with supraglottic combined-frequency jet ventilation than with subglottic monofrequent jet ventilation via the Mon-Jet catheter. IMPLICATIONS: This study demonstrates that the combination of high- and low-frequency supraglottic jet ventilation via a jet ventilation laryngoscope provides a better pulmonary gas exchange and allows more accurate airway pressure monitoring during microlaryngeal surgery than subglottic monofrequent jet ventilation via an endotracheal catheter.

Tubeless translaryngeal superimposed jet ventilation.

Microsurgical endoscopic interventions of the larynx offer an optimal approach to the surgeon by providing an unrestricted operative field. During such operations, ventilating the patient should in no way be impaired. For this reason we have developed a new type of tubeless jet ventilation which consists of both low-frequency and superimposed high-frequency jet ventilation. In addition, we have integrated two specifically sized jets into a Kleinsasser laryngoscope, placing them at different sites. This technique guarantees adequate ventilation with an oxygen-air blend. Due to the Venturi effect, air and tidal volumes are also enhanced when passing through the external open end of the laryngoscope. This type of tubeless jet ventilation was applied to more than 60 patients, using a prototype jet. Anesthesia consisted of a continuous intravenous administration of propofol, with sufentanil and vecuronium given as needed. Clinical results revealed optimal ventilation of all patients without hypercapnia or other complications. Operative conditions for the surgeon were also very satisfactory. Findings demonstrated that this type of tubeless jet ventilation is also particularly suited for laryngeal laser surgery, thus avoiding flammable tubes and noxious anesthetics.

High-frequency jet ventilation in European and North American institutions: developments and clinical practice.

Respiratory support with high-frequency jet ventilation has been advocated during airway surgery or to improve pulmonary mechanics and gas exchange in patients with bronchopleural fistulae or pulmonary insufficiency. Despite a large body of published evidence describing its benefits as an alternative ventilatory approach in anaesthesia and intensive care medicine, its application has not gained widespread acceptance and is restricted to specialized centres. To review the literature on high-frequency jet ventilation in European and North American institutions, we performed a search in a computerized database (MEDLINE) covering the period from 1990 until the present time, describing the use of high-frequency jet ventilation in over 7000 patients. Various modes to apply high-frequency jet ventilation during airway surgery have been established, but its value in intensive care is controversial. We report our experience with combined high-frequency jet ventilation and provide guidelines for its safe application.

Respiratory efficacy of subglottic low-frequency, subglottic combined-frequency, and supraglottic combined-frequency jet ventilation during microlaryngeal surgery.

UNLABELLED: We tested the respiratory efficacy of different jet ventilation techniques (subglottic low-frequency versus subglottic combined-frequency and subglottic combined-frequency versus supraglottic combined frequency) in patients undergoing microlaryngeal surgery. The PaCO(2) and the quotient of arterial oxygen tension (PaO(2)) over FIO(2) were measured. After anesthetic induction (propofol, remifentanil, vecuronium), an endotracheal Mon-Jet catheter (Xomed, Jacksonville, FL) for subglottic jet ventilation and a laryngoscope for supraglottic jet ventilation (Carl Reiner G.m.b.H., Vienna, Austria) were inserted. In Group 1 (n = 18), subglottic low-frequency (15 breaths/min), combined-frequency (600 and 15 breaths/min), and low-frequency jet ventilation was subsequently performed (15 min each). In Group 2 (n = 19), the sequence was supraglottic, subglottic, and supraglottic combined-frequency jet ventilation. The driving pressures were initially adjusted to achieve normocapnia and were not changed during the entire study period. The FIO(2) was measured endotracheally. The Wilcoxon's signed rank test was applied. In Group 1, PaCO(2) and PaO(2)/FIO(2) improved significantly after switching from subglottic low-frequency to subglottic combined-frequency jet ventilation (PaCO(2), from 46.6 +/-8.3 to 42.1+/-8.1 mm Hg; PaO(2)/FIO(2), from 311+/-144 to 361+/-141 mm Hg; P<0.05). In Group 2, PaCO(2) increased and PaO(2)/FIO(2) decreased significantly after switching from supraglottic to subglottic combined-frequency jet ventilation (PaCO(2), from 39.4+/-7.1 to 45.9+/-7.5 mm Hg; PaO(2)/FIO(2), from 415+/-114 to 351+/-129 mm Hg; P<0.05). We conclude that subglottic combined-frequency jet ventilation is less effective than supraglottic combined-frequency ventilation, but more effective than subglottic low-frequency jet ventilation. IMPLICATIONS: The combination of high and low respiratory frequencies (600 and 15 breaths/min) improves pulmonary gas exchange during subglottic jet ventilation via an endotracheal catheter. However, subglottic combined-frequency jet ventilation is less effective than supraglottic combined-frequency jet ventilation via a jet ventilation laryngoscope.

[Tube-free translaryngeal superposed jet ventilation]. / Tubuslose translaryngeale superponierte Jet-Ventilation.

Microsurgical operations on the larynx require sufficient space for the surgeon in order to achieve the best surgical result. After preliminary experimental studies we integrated two jets of a specific size into the Kleinsasser tube. Simultaneously, we developed a "superimposed jet-ventilation system", which consists of a low-frequency jet ventilation and superimposed high-frequency jet ventilation. Respiration was maintained with a mixture of oxygen and air, whereby an additional increase in air and volume via the Kleinsasser tube, which is open on the outside, can be sustained on account of the Venturi effect. We tested this tubeless translaryngeal superimposed jet-ventilation system in 48 patients. Anesthesia was carried out by continuous intravenous administration of Propofol and intermittent doses of Sufentanil and Vecuronium as required. The clinical results showed optimal ventilation without hypercapnia. The arterial pC0(2) levels were below 42 mmHg. The arterial p0(2) levels were above 120 mmHg with a FIO2 of 40%. No complications were observed with regard to respiration during any of the operations. The surgeon had optimal conditions to carry out the operation. Because of the absence of a plastic tube, inhalation anesthetics and nitrous oxide, laryngeal laser surgery is another field of application for which this form of tubeless jet ventilation is excellently suited. We tested it with 12 patients, and no complications due to laser anesthesia were observed. We consider this form of a tubeless superimposed translaryngeal jet ventilation to be a great improvement in microlaryngeal surgery.

[Function preserving surgical therapy of head-neck tumors with the CO2 laser]. / Die funktionserhaltende chirurgische Therapie von Kopf-Hals-Tumoren mit dem CO2-Laser.

The use of microscopically controlled laser surgery to treat tumors of the upper aerodigestive tract has as a function maintaining form of treatment gained significance. It is an alternative to conventional surgery, which often makes organ removal necessary. We report on our experience with 85 patients who underwent a laser surgical resection of malignomas of the upper aerodigestive tract. The aim of transoral laser surgery is a histologically confirmed radical tumor resection. Tumor resection can be individually adapted according to the tumor extent. An unnecessary resection of cartilage and muscles can be avoided. Provided the appropriate indication is given, laser surgery yields good oncologic and excellent functional results.

[Preliminary experiences with superimpoposed high-frequence jet ventilation in intensive care]. / Erste Erfahrungen mit der Superponierten Hochfrequenz-Jetventilation in der Intensivmedizin.

The study aimed to evaluate whether superimposed high-frequency jet ventilation (SHFJV) is a useful tool in intensive care medicine to ventilate patients with pulmonary insufficiency. METHODS. SHFJV is the simultaneous application of low- and high-frequency jet ventilation performed using a specially designed ventilator. SHFJV versus conventional mechanical ventilation (CMV) was were applied in three groups of patients. Group 1 (Gr 1) included patients without pulmonary insufficiency; group 2 (Gr 2) patients had moderate and those in group 3 (Gr 3) had severe pulmonary insufficiency. RESULTS. In Gr 1 and Gr 2, SHFJV was associated with a significant decrease in mean airway pressure (mPAW 12.9 vs. 13.3 mm Hg, P < 0.05). In Gr 3 oxygenation was significantly better with SHFJV (mean paO2 140.1 vs. 109.9 mm Hg, P < 0.05; mean FiO2 0.66 vs. 0.86, P < 0.05). Other parameters, such as maximum airway pressure (Pmax) and mean Paw, were significantly lower with SHFJV than CMV (mean Pmax 29.6 vs. 40.1 mm Hg, mean Paw 18 vs. 21.9 mm Hg, P < 0.05). Intrapulmonary shunt fractions showed a significant decrease with SHFJV (24.6 vs. 34.4, P < 0.05). CONCLUSIONS. Significant differences were observed primarily in Gr 3 patients, indicating that patients with severe pulmonary insufficiency may benefit from SHFJV. SHFJV may thus represent an alternative mode of ventilation in critically ill patients.

[Clinical experiences with the double jet technique superimposed HFJV (high frequency jet ventilation) during larygotracheal surgery]. / Klinische Erfahrungen mit der Doppel-Jet-Technik: Die Superponierte Hochfrequenz-Jet-Ventilation in der Larynxchirurgie.

OBJECTIVE: Single-frequency high-frequency jet ventilation (HFJV) is an established ventilatory technique during laryngotracheal surgery. This study describes the clinical use of combined HFJV, characterised by the simultaneous application of a low-frequent (LF) and a high-frequent (HF) jet stream. METHODS: Two jet streams with different pulsatile frequency (HF approx. 10 Hz, LF 10-30 bpm) and adjustable driving pressures were applied supraglottically by means of a special jet laryngoscope in patients undergoing elective laryngotracheal surgery during total intravenous anaesthesia. HFJV was performed using a pneumatic or electronic jet respirator connected to the central gas supply. RESULTS: 134 patients were submitted to tubeless HFJV applying the double-jet technique using the jet-laryngoscope. Duration of HFJV was < or = 30 min in 60 patients (45%), between 30 and 60 min in 49 patients (36%), and > or = 60 min in 25 patients (19%). Classification into 3 groups according to weight ((I < 65 kg, II = 65-84 kg, III > or = 85 kg) using driving pressures of 1.52 +/- 0.47 bar, 1.64 +/- 0.78 bar, and 1.69 +/- 0.67 bar for the HF jet and 1.78 +/- 0.54 bar, 1.90 +/- 0.48 bar, and 2.00 +/- 0.49 bar for the NF jet demonstrated differences in paO2 (156 +/- 45 [I] vs 126 +/- 34 [II] vs 96 +/- 18 [III] mm Hg) and paCO2 (42 +/- 9 und 44 +/- 8 vs 48 +/- 8 mm Hg) using comparable FjetO2 (0.6 +/- 0.2). Supraglottic pressures were 11.6 +/- 6.8, 11.5 +/- 7.0, und 12.6 +/- 7.1 cm H2O (I-III). No ventilator-related adverse events were observed. CONCLUSION: Tubeless supraglottic HFJV utilizing two jet streams with low and high frequency was effective in patients during laryngotracheal surgery. The application of two jet streams results in phasic changes of airway pressures between an inspiratory and expiratory pressure level, and facilitates application of enlarged tidal volumes. As demonstrated, oxigenation and ventilation is compromised by increased body weight. Superimposed HFJV (double-jet technique) enables the supraglottic ventilation of heavy patients and/or in the presence of airway stenoses during laryngotracheal surgery without need to use maximum driving pressures.

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. METHODS: Tubeless combined HFJV characterised by the simultaneous supralaryngeal application of a low-frequency (LF) and a high-frequency (HF) jet stream was evaluated in a clinical study in 10 children undergoing elective laryngotracheal CO2 laser surgery. Additionally, pressure and flow characteristics were determined with the use of a paediatric test lung. HFJV was applied by means of a modified Kleinsasser laryngoscope with integrated metal injectors. In addition to pulse oximetry, monitoring of ECG, heart rate and blood pressure, supraglottic airway pressure was measured and arterial blood gases were analysed. RESULTS: Tubeless combined HFJV was used in 10 infants and children (mean age 4.6 yr, range 2 months-10 years) undergoing 17 consecutive endoscopic procedures with CO2 laser microsurgery of the larynx or the trachea under general anaesthesia. The mean duration of supralaryngeal HFJV was 46 min (range 15-75 min). Mean driving pressures of the HF and the LF jet streams were 0.75 bar and 0.95 bar, respectively. Inspiratory oxygen ratios were in the range 0.4-1.0. HFJV resulted in mean PaO2 and PaCO2 values of 19.7 kPa and 6.1 kPa, respectively. No complications during HFJV were observed. In the test lung, combined HFJV applied with driving pressures of 0.7-1.0 bar and 0.9-1.2 bar for HF and LF jet ventilation, respectively, resulted in maximum peak and baseline distal airway pressures of 17.6 cm H2O and 5.4 cm H2O, respectively. CONCLUSION: The application of the combined double frequency HFJV was effective in maintaining gas exchange in the presence of laryngeal or tracheal stenoses. It provided good visibility of anatomical structures and offered space for surgical manipulation, avoiding the use of combustible material inside the larynx or trachea.