We compared systemic (aortic) blood flow and cerebral blood flow velocity in 30 patients randomly allocated to receive either propofol or sevoflurane anaesthesia. Cerebral blood flow velocity (CBFv) was measured in the middle cerebral artery using transcranial Doppler. Systemic blood flow velocity (SBFv) was measured in the aorta using transthoracic Doppler sonography at the level of the aortic valve. Bispectral index (BIS) was used to measure the depth of anaesthesia. Measurements were made in the awake patient and repeated during propofol or sevoflurane anaesthesia, with BIS measurements of 40-50. The effects of SBFv on CBFv were estimated by calculating the cerebral/systemic blood flow velocity-index (CsvI). A CsvI value of 100 indicating a 1 : 1 relationship between CBFv and SBFv. The results demonstrated that propofol anaesthesia produced a significantly greater reduction in CsvI than did sevoflurane anaesthesia [propofol: 60 (19); sevoflurane: 83 (16), p = 0.009, t-test]. This suggests a direct reduction in CBFv independent of SBFv during propofol anaesthesia. The greater reduction of CBFv occurring during propofol anaesthesia may be due to lower cerebral metabolic demand compared with sevoflurane anaesthesia at comparable depths of anaesthesia.

BACKGROUND AND OBJECTIVE:We studied the influence of systemic (aortic) blood flow velocity on changes of cerebral blood flow velocity under isoflurane or sevoflurane anaesthesia.METHODS:Forty patients (age: isoflurane 24-62 years; sevoflurane 24-61 years; ASA I-III) requiring general anaesthesia undergoing routine spinal surgery were randomly assigned to either group. Cerebral blood flow velocity was measured in the middle cerebral artery by transcranial Doppler sonography (depth: 50-60 mm). Systemic blood flow velocity was determined by transthoracic Doppler sonography at the aortic valve. Heart rate, arterial pressure, arterial oxygen saturation and body temperature were monitored. After standardized anaesthesia induction (propofol, remifentanil, vecuronium) sevoflurane or isoflurane were used as single agent anaesthetics. Cerebral blood flow velocity and systemic blood flow velocity were measured in the awake patient (baseline) and repeated 5 min after reaching a steady state of inspiratory and end-expiratory concentrations of 0.75, 1.00, and 1.25 mean alveolar concentrations of either anaesthetic. To calculate the influence of systemic blood flow velocity on cerebral blood flow velocity, we defined the cerebral-systemic blood flow velocity index (CSvI). CSvI of 100% indicates a 1:1 relationship of changes of cerebral blood flow velocity and systemic blood flow velocity.RESULTS:Isoflurane and sevoflurane reduced both cerebral blood flow velocity and systemic blood flow velocity. The CSvI decreased significantly at all three concentrations vs. 100% (isoflurane/sevoflurane: 0.75 MAC: 85 +/- 25%/81 +/- 23%, 1.0 MAC: 79 +/- 19%/74 +/- 16%, 1.25 MAC: 71 +/- 16%/79 +/- 21%; [mean +/- SD] P = 0.0001).CONCLUSIONS:The reduction of the CSvI vs. 100% indicates a direct reduction of cerebral blood flow velocity caused by isoflurane/sevoflurane, independently of systemic blood flow velocity.

s and Programme: European Society of Anaesthesiologists; 9th Annual Meeting with the Swedish Society of Anaesthesiology; Gothenburg, Sweden, 7-10 April 2001: Ambulatory Anaesthesia

European Society of Anaesthesiologists; 8th Annual Meeting with the Austrian International Congress; Vienna, Austria, 1-4 April 2000

Zusammenfassung Die 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.

UNLABELLED: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.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.

In a 35-year old male patient with laryngeal carcinoma an acute respiratory insufficiency with early hypoxaemia developed due to massive laryngeal stenosis. An endotracheal intubation was not possible since the available lumen was too small. Tracheotomy using local anaesthesia was not possible since spontaneous respiration with a Venturi mask applying 100% oxygen was not sufficient and the patient was becoming restless and agitated due to the hypoxaemia. Transcutaneous jet ventilation was considered to be too risky since the needle would have to pass highly vascularised tumour tissue and the detection of such a small rest lumen would have been quite difficult. Ventilating the patient using a percutaneous catheter would have been very risky as well since, due to the massive stenosis, a sufficient expiration would not be likely and therefore was considered to carry a high risk of barotrauma. The patient was ventilated under general anaesthesia via a specially designed endoscopy tube with integrated jet nozzles applying superimposed high frequency jet ventilation above the stenosis. Since it was possible to achieve sufficient ventilation during the inspection of the larynx the jet laryngoscope was left in place and the supporting apparatus was covered with sterile drapes. The tracheotomy was performed using the superimposed high frequency jet ventilation. Throughout the procedure oxygenation and ventilation were adequate. The laryngectomy performed several days later revealed a cauliflower type protrusion into the tracheal lumen and a 5 cm long stenosis of the larynx with a lumen of 3 mm.

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 (Or 3) had severe pulmonary insufficiency.Results. In Gr 1 and Gr2, SKFJV 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 paO(2) 140.1 vs. 109.9 mm Hg, P<0.05; mean FiO(2) 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.

OBJECTIVE:Patients with increased intracranial pressure or vasospasm after subarachnoidal haemorrhage with decreased cerebral perfusion present a special problem on developing respiratory insufficiency, since kinetic therapy or extracorporal life support are contraindicated. Superimposed High Frequency Jet Ventilation (SHFJV) has been shown to be of benefit in ventilating patients with pulmonary insufficiency. The aim of this study was to evaluate if SHFJV could be safely applied in patients with critical cerebral blood flow; if so, SHFJV might be beneficial when pulmonary insufficiency occurs concomitantly.METHODS:The study was performed in 14 patients (3 with pulmonary insufficiency) applying first moderate hyperventilation (paCO2 31 to 36 mmHg) followed by increased hyperventilation (paCO2 27 to 30 mmHg) with CMV and SHFJV and measuring intracranial pressure (ICP), cerebral perfusion pressure (CPP) and blood flow velocity (BFV) of the middle cerebral artery. BFV of the middle cerebral artery which correlates closely to the cerebral blood flow, was measured continuously with transcranial Doppler ultrasound.RESULTS:CMV: Increased hyperventilation leads to a statistically significant increase in paO2 (121.3 to 147.2 mmHg, p < 0.05), SaO2 (98.5% to 99.2%, p < 0.05) and decrease in BFV (systole 115.9 to 89.6 cm/s, diastole 44.6 to 31.8 cm/s, p < 0.05). Heart rate, mean arterial blood pressure, ICP and ventilation parameters did not show any statistically significant differences. SHFJV: During SHFJV the parameters demonstrated similar patterns as during CMV. However, none of the changes were statistically significant (paO2 111.9 to 125.9 mmHg, SaO2 97.9 to 98.8, BFV systole 106 to 95 cm/s, diastole 52.7 to 42.4 cm/s, n.s.). After calculating the mean BFV according to the Markwalder formula to a standard paCO2 of 40 mmHg CMV and SHFJV were compared to one another. No statistical difference was seen between the two different ventilation techniques.CONCLUSION:In patients with increased ICP, pulmonary complications such as pneumonia or ARDS are frequently observed. Since there are indications that SHFJV is of benefit in pulmonary insufficiency, the study was conducted to demonstrate that SHFJV can be safely applied in patients with increased ICP.

The 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, paO(2) was 69.4 mm Hg and the oxygen saturation 88.3% with a F1O2 of 1.0. Significant improvement was observed within 30 min after star ring SHFJV with inhaled NO (paO(2) 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.

The 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 F1O2 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.

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.

Surgery by three-dimensional (3D) endoscopy is being used routinely in abdominal surgery and, in special cases, in thoracic surgery; however, it has not been reported as being used in microlaryngeal surgery. Methods. We inserted a 3-D endoscope into a jet laryngoscope and studied the pressure properties at the tip of the laryngoscope as well as intrapulmonary pressures while applying superimposed high-frequency jet ventilation. The studies were conducted initially using a lung simulator, and then in seven patients undergoing microlaryngeal surgery. Results. Due to the rather large 3-D endoscope, the diameter of the jet laryngoscope was reduced by between 25.2% and 70.9%, depending on its size. The measurements on the lung simulator revealed that reduction of laryngoscope diameter leads to an increase in the following parameters: expiratory resistance, tidal volume, and peak inspiratory pressure. The mean FiO2 was 0.74±0.1; the mean paO2 was 169.2±80.4 mm Hg; and the mean paCO2 was 40.9±2.4 mm Hg. The mean airway pressure was 19±5.3 mm Hg prior to insertion of the endoscope and 12.3±6.9 mm Hg after insertion. The mean positive end-expiratory pressure values increased from 2±0.6 to 3.6±2.3 mm Hg. Reduction of the working pressure resulted in restoration of the initial inspiratory pressures and tidal volumes. Conclusions. In the clinical application of 3-D endoscopy via a jet laryngoscope, it was possible to achieve sufficient ventilation, inspection of the surgical field, and performance of the surgical procedure. A CO2 laser was used without changing the ventilation regime. Although technical alterations would be desirable for its application to microlaryngeal surgery, it is presently possible to safely use the 3-D endoscope via the jet laryngoscope for microlaryngeal surgery, presenting the surgeon with new possibilities in voice-improving microsurgery of the larynx.

The 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, paO 2 was 69.4 mm Hg and the oxygen saturation 88.3% with a F I O 2 of 1.0. Significant improvement was observed within 30 min after starting SHFJV with inhaled NO (paO 2 282.9 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.

Surgery by three-dimensional (3D) endoscopy is being used routinely in abdominal surgery and, in special cases, in thoracic surgery; however, it has not been reported as being used in microlaryngeal surgery. Methods. We inserted a 3-D endoscope into a jet laryngoscope and studied the pressure properties at the tip of the laryngoscope as well as intrapulmonary pressures while applying superimposed high-frequency jet ventilation. The studies were conducted initially using a lung simulator, and then in seven patients undergoing microlaryngeal surgery. Results. Due to the rather large 3-D endoscope, the diameter of the jet laryngoscope was reduced by between 25.2% and 70,9%, depending on its size. The measurements on the lung simulator revealed that reduction of laryngoscope diameter leads to an increase in the following parameters: expiratory resistance, tidal volume, and peak inspiratory pressure. The mean FiO 2 was 0.74 ± 0. 1; the mean paO 2 was 169.2 ± 80.4 mmHg; and the mean paCO 2 was 40.9 ± 2.4 mmHg. The mean airway pressure was 19 ± 5.3 mmHg prior to insertion of the endoscope and 12.3 ± 6.9 mmHg after insertion. The mean positive end-expiratory pressure values increased from 2 ± 0.6 to 3.6 ± 2.3 mmHg. Reduction of the working pressure resulted in restoration of the initial inspiratory pressures and tidal volumes. Conclusions. In the clinical application of 3-D endoscopy via a jet laryngoscope, it was possible to achieve sufficient ventilation, inspection of the surgical field, and performance of the surgical procedure. A CO 2 laser was used without changing the ventilation regime. Although technical alterations would be desirable for its application to microlaryngeal surgery, it is presently possible to safely use the 3-D endoscope via the jet laryngoscope for microlaryngeal surgery, presenting the surgeon with new possibilities in voice-improving microsurgery of the larynx

Surgery by three-dimensional (3D) endoscopy is being used routinely in abdominal surgery and, in special cases, in thoracic surgery; however, it has not been reported as being used in microlaryngeal surgery.Methods. We inserted a 3-D endoscope into a jet laryngoscope and studied the pressure properties at the tip of the laryngoscope as well as intrapulmonary pressures while applying superimposed high-frequency jet ventilation. The studies were conducted initially using a lung simulator, and then in seven patients undergoing microlaryngeal surgery.Results. Due to the rather large 3-D endoscope, the diameter of the jet laryngoscope was reduced by between 25.2% and 70.9%, depending on its size. The measurements on the lung simulator revealed that reduction of laryngoscope diameter leads to an increase in the following parameters: expiratory resistance, tidal volume, and peak inspiratory pressure. The mean FiO(2) was 0.74+/-0.1; the mean paO(2) was 169.2+/-80.4 mmHg; and the mean paCO(2) was 30.9+/-2.4 mmHg. The mean airway pressure was 19+/-5.3 mmHg prior to insertion of the endoscope and 12.3+/-6.9 mmHg The mean positive end-expiratory pressure values increased from 2+/-0.6 to 3.6+/-2.3 mmHg. Reduction of the working pressure resulted in restoration of the initial inspiratory pressures and tidal volumes.Conclusions. In the clinical application of 3-D endoscopy via a jet laryngoscope, it was possible to achieve sufficient ventilation, inspection of the surgical field, and performance of the surgical procedure. A CO2 laser was used without changing the ventilation regime. Although technical alterations would be desirable for its application to microlaryngeal surgery, it is presently possible to safely use the 3-D endoscope via the jet laryngoscope for microlaryngeal surgery, presenting the surgeon with new possibilities in voice-improving microsurgery of the larynx.

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.

In a 35-year old male patient with laryngeal carcinoma an acute respiratory insufficiency with early hyperaemia developed due to massive laryngeal stenosis. An endotracheal intubation was not possible since the available lumen was too small. Tracheotomy using local anaesthesia was not possible since spontaneous respiration with a Venturi mask applying 100% oxygen was not sufficient and the patient was becoming restless and agitated due to the hypoxaemia. Transcutaneous jet ventilation was considered to be too risky since the needle would have to pass highly vascularised tumour tissue and the detection of such a small rest lumen would have been quite difficult. Ventilating the patient using a percutaneous catheter would have been very risky as well since, due to the massive stenosis, a sufficient expiration would not be likely and therefore was considered to carry a high risk of barotrauma. The patient was ventilated under general anaesthesia via a specially designed endoscopy tube with integrated jet nozzles applying superimposed high frequency jet ventilation above the stenosis. Since it was possible to achieve sufficient ventilation during the inspection of the larynx the jet laryngoscope was left in place and the supporting apparatus was covered with sterile drapes. The tracheotomy was performed using the superimposed high frequency jet ventilation. Throughout the procedure oxygenation and ventilation were adequate. The laryngectomy performed several days later revealed a cauliflower type protrusion into the tracheal lumen and a 5 cm long stenosis of the larynx with a lumen of 3 mm.

In laser surgery of the larynx the surgeon and the anaesthesist have to compete for the limited space available. The surgeon requiring good visibility and an undisturbed operating area whereas the anesthetist has to ensure sufficient ventilation of the patient. Further, complications of anaesthesia and laser must be avoided. These requirements are met by using the jet-tube (jet-laryngoscope) with two integrated nozzles applying simultaneously low- and high-frequency jet-ventilation giving the surgeon total access to the area operated on, and at the same time enables safe ventilation of the patient. Of 334 operations with the tubeless ventilation technique 76 cases were laser surgical interventions. In 6 patients stenoses were enlarged. The average duration of the jet-ventilation was 25 +/- 10 minutes. The maximum duration of a laser surgical intervention was 140 minutes. The age distribution of the patients was 18 months to 82 years. In all patients pulmonary gas exchange was satisfactory. We believe that the advantage of the tubeless jet-ventilation is: optimal visibility and surgical freedom for the surgeon, no time limitation, even in very severe stenoses. Since no volatile anaesthetics or any type of endotracheal tube are applied there is no danger of interaction with the laser when using the SHFJV via the jet-laryngoscope. Application of the tubeless jet-ventilation technique is however limited if patients suffer from severe pulmonary obstruction; likewise highly obese patients and patients in whom massive bleeding occurs are not amenable to tubeless jet-ventilation.