No abstract available.
High-Frequency Ventilation*

Currently conventional modes of controlled mechanical ventilation, such as intermittent positive pressure ventilation (IPPV) and continuous positive pressure ventilation (CPPV), with high volumes and low rates are utilized for the rhythmic inflation of the lungs. Basically the functional characteristics of these systems have not changed since Bjork and Engstrom first reviewed them in 1955 (Bjork and Engstrom 1955; Sjostrand 1983). Impairment of cardiovascular function and increasing the incidence of barotrauma with high airway pressure were problems which have needed to be solved. Thus respiratory support using high rates and low tidal volumes of ventilation was given. High-frequency ventilation(HFV) is not totally new idea, prototypes of it are found in nature in humming birds, insects and newborn babies. Moreover, HFV was reported in 1915 by Handerson who said that an adequate gas exchange could take place with a tidal volume less than the anatomical deadspace. But since the introduction of HFV in 1967, the basic concept of respiratory physiology has changed (Sjostrand and Smith 1983). HFV has received much attention in the last 20 years, resulting in a considerable accumulation of information. Many experimental and clinical studies have detailed the potential advantages of HFV but indicate that much work needs to be done to define and clarify the clinical role of these techniques and suggest that the standardized, reliable equipment with safety systems be developed. The purpose of this review is not to offer definite information for further investigation, but simply to provide background information for a better understanding of the experimental and clinical results recently achieved by many other researchers. Limited foci are as follows: 1) Definition and classification of HFV. 2) Technical developments and considerations. 3) Physiologic aspects of HFV. 4) Clinical applications. 5) Comparative studies between IPPV and HFV. 6) Problems and looking ahead.
Comparative Study ; High-Frequency Jet Ventilation ; High-Frequency Ventilation*/classification ; Human ; Intermittent Positive-Pressure Ventilation

Currently conventional modes of controlled mechanical ventilation, such as intermittent positive pressure ventilation (IPPV) and continuous positive pressure ventilation (CPPV), with high volumes and low rates are utilized for the rhythmic inflation of the lungs. Basically the functional characteristics of these systems have not changed since Bjork and Engstrom first reviewed them in 1955 (Bjork and Engstrom 1955; Sjostrand 1983). Impairment of cardiovascular function and increasing the incidence of barotrauma with high airway pressure were problems which have needed to be solved. Thus respiratory support using high rates and low tidal volumes of ventilation was given. High-frequency ventilation(HFV) is not totally new idea, prototypes of it are found in nature in humming birds, insects and newborn babies. Moreover, HFV was reported in 1915 by Handerson who said that an adequate gas exchange could take place with a tidal volume less than the anatomical deadspace. But since the introduction of HFV in 1967, the basic concept of respiratory physiology has changed (Sjostrand and Smith 1983). HFV has received much attention in the last 20 years, resulting in a considerable accumulation of information. Many experimental and clinical studies have detailed the potential advantages of HFV but indicate that much work needs to be done to define and clarify the clinical role of these techniques and suggest that the standardized, reliable equipment with safety systems be developed. The purpose of this review is not to offer definite information for further investigation, but simply to provide background information for a better understanding of the experimental and clinical results recently achieved by many other researchers. Limited foci are as follows: 1) Definition and classification of HFV. 2) Technical developments and considerations. 3) Physiologic aspects of HFV. 4) Clinical applications. 5) Comparative studies between IPPV and HFV. 6) Problems and looking ahead.
Comparative Study ; High-Frequency Jet Ventilation ; High-Frequency Ventilation*/classification ; Human ; Intermittent Positive-Pressure Ventilation

High frequency ventilation has been used experimentally and clinically in a variety of situations. This report describes two cases in which high frequency jet ventilation was used to provide adequate ventilation during thoracic surgery. A solenoid valve controlled ventilator at rates of 100 breaths/min. with a double lumen tube provided adequate gas exchange for these patients with an open chest. The minimal lung movement during high frequency jet ventilation was found to provide excellent operating conditions without undue cardiovascular embarrassment. This case report demonstrates the use of high frequency jet ventilation in two adults undergoing operation ofr pulmonary lobectomy and biopay with segmental resection.
Adult ; High-Frequency Jet Ventilation ; High-Frequency Ventilation ; Humans ; Lung ; Thoracic Surgery* ; Thorax ; Ventilation* ; Ventilators, Mechanical

High frequency jet ventilation (HFJV) has advantage for laryngomicrosurgery that the transit of a small airway tube through the surgical field causes much less interference with surgery. We experienced a case of tension pneumothorax during high frequency jet ventilation. The possible cause of barotrauma in this case was obstruction of gas escape. It is recommened that meticulous care is taken to ensure and adequate pathway for expiration when HFJV is used.
Barotrauma ; High-Frequency Jet Ventilation ; Pneumothorax* ; United Nations ; Ventilation*

BACKGROUND: We examined the effects of varying inspiratory to expiratory (I : E) ratio on gas exchange and hemodynamics during high frequency partial liquid ventilation (HFPLV), a combination of high frequency ventilation (HFV) and partial liquid ventilation (PLV), in a rabbit model of acute lung injury. METHODS: Twelve rabbits treated with repeated saline lavage were divided into two groups. In the HFPL group (n = 6), 6 ml/kg of perfluorodecaline was administered through the endotracheal tube. Rabbits in this group and in the HFJ group (n = 6) were treated with high frequency jet ventilation (HFJV) at I : E ratios of 1 : 1, 1 : 2, and 1 : 3 for 15 minutes, and arterial blood gas, mixed venous blood gas and hemodynamic parameters were measured. RESULTS: We observed no significant respiratory and hemodynamic differences between the two groups. At an I : E ratio of 1 : 1, the PaO2 was significantly higher, and the shunt rate and PaCO2 were significantly lower in both groups, compared with I : E ratios of 1 : 2 and 1 : 3. Cardiac output at the 1 : 3 I : E ratio was significantly higher than at 1 : 1. CONCLUSIONS: These findings indicate that, in this model, a 1 : 1 I : E ratio was superior for oxygenation and ventilation than I : E ratios of 1 : 2 or 1 : 3, while having no detrimental effects on hemodynamics.
Acute Lung Injury ; Cardiac Output ; Hemodynamics ; High-Frequency Jet Ventilation ; High-Frequency Ventilation ; Liquid Ventilation ; Oxygen ; Rabbits ; Therapeutic Irrigation ; Ventilation

High frequency ventilation considerably reduces the risk of barotrauma due to low peak airway pressure compared to conventional mechanical ventilation. This risk, however, is also preaent with high frequency jet ventilation (HFJV) if excessive driving preasure are used and, above all if expiration is impeded. We investigated the effects of outflow resistance, which was varied by connecting different size of tube (ID 8.0, 7.5, 7.0, 6.5, 5.5, 5.0, 4.5, 4.0 mm), which was cut in 10 cm length, to the proximal site of endotracheal tube (ID 8.0 mm), which was inserted into the trachea of anesthetized dogs with a attached airway pressure monitoring catheter externally, in different driving pressure (2 kg/cm2, 1 kg/cm2) and frequency (100beats/min, 200beats/min) on the intra-airway preesure during HFJV. HFJV was performed with a catheter (diameter 2.5 mm) which was inaerted through endotracheal tube and located 1 cm proximal to the tip of endotracheal tube. Intra-airway pressure was acutely increased with the tube size of smaller than 5.5 mm in driving pressure 2 kg/cm2 and 5.0 mm in driving pressure 1 kg/cm2 compared to previous size of tube. 2 kg/cm2 of driving pressure showed significant higher airway pressure compared to 1 kg/cm in any size of tube. There was no difference in airway pressure by varing of frequency with same driving preasure. In summary, pulmonary barotrauma due to higher airway pressure may be occur if HFJV catheter occupied more than 25% of outflow tract area especially in higher driving pressure.
Airway Resistance ; Animals ; Barotrauma ; Catheters ; Dogs ; High-Frequency Jet Ventilation* ; High-Frequency Ventilation ; Respiration, Artificial ; Trachea ; Ventilation

BACKGROUND: In some cases of one-lung ventilation (OLV), hypoxemia may occur secondarily to the obligatory right to left transpulmonary shunt through the collapsed lung. We investigated the efficacy of high frequency jet ventilation (HFJV) to the non-dependent lung which rendered to be manually collapsed by surgeon and not to be reinflated, in improving systemic oxygenation and ventilation during OLV while ventilating the dependent lung with intermittent positive pressure ventilation. METHODS: Investigation was carried out on 20 ASA 2 or 3 patients who underwent thoracotomy in lateral decubitus position. The patients were randomly allocated into HFJV group (n = 11) or CPAP group (n = 9). In HFJV group, 20 minutes after OLV began, HFJV with driving pressure 1.0 bar, Ti 30%, and frequency 150 cycles/min, was applied to the non-dependent lung. In CPAP group, 5 cmH2O of CPAP was applied to the non-dependent lung without re-inflation. We compared the changes of PaO2, PaCO2, AaDO2 and pulmonary shunt, before and after HFJV or CPAP was applied to the non-dependent lung during OLV. RESULTS: AaDO2 and pulmonary shunt were decreased significantly and therefore, PaO2 was increased significantly when HFJV was applied to the non-dependent lung (P < 0.05, respectively). PaO2, AaDO2 and pulmonary shunt were not improved after 5 cmH2O of CPAP was applied to the non-dependent lung without re-inflation. In HFJV group, PaCO2 measured after HFJV was not decreased significantly compared with that before HFJV. CONCLUSIONS: HFJV to the non-dependent lung during OLV improved systemic oxygenation, even after the non-dependent lung collapsed completely but did not enhance CO2 elimination. 5 cmH2O of CPAP to the non-dependent lung, which was completely collapsed and not re-inflated, did not improve systemic oxygenation.
Anoxia ; High-Frequency Jet Ventilation* ; Humans ; Intermittent Positive-Pressure Ventilation ; Lung* ; One-Lung Ventilation* ; Oxygen* ; Thoracotomy ; Ventilation

High frequency ventilation (HFV) is a new ventilatory technique that uses very small tidal volume (less than the anatomic dead space) and high frequency, and classified 4 distinct types according to frequency and mode of gas delivery. The mechanism of gas transport of high frequency oscillation ventilation (HFOV) is somewhat different to other types of HFV. To evaluate the determinants of PaCO² in HFOV, a study was done with a HFOV on 9 cats, and the results are: 1) PaCO² was not correlated with frequency at the constant stroke volume (6 voltage) and bias flow (6 L/minutes). 2)PaCO² was correlated with stroke volume but not with bias flow under the constant frequency (15 Hz/min) and bias flow (3 to 6 L/min). From above results, the main determinant of PaCO² on artificial ventilation with HFOV was stroke volume, but further study between flow, the site of delivery to the airway and humidification of bias flow and CO² elimination is required in future research.
Animals ; Bias (Epidemiology) ; Cats* ; High-Frequency Ventilation* ; Stroke Volume ; Tidal Volume ; Ventilation

Neonates with severe respiratory distress syndrome who require high levels of assisted ventilation have a high mortality and morbidity rate. Morbidity is mainly composed of bronchopulmonary dysplasia which is a result of air leak syndrome(ALS), oxygen toxicity. Even with unsolved controversy, there is a possibility that high-frequency oscillatory ventilation would decrease the development or progression of ALS in infants with severe respiratory distress syndrome. ALS is defined as pulmonary interstitial emphysema or gross air leak such as pneumothorax. We experienced HFOV to be effective in the treatment of newborn infant with pneumothorax.
Bronchopulmonary Dysplasia ; Emphysema ; High-Frequency Ventilation ; Humans ; Infant ; Infant, Newborn ; Mortality ; Oxygen ; Pneumothorax ; Ventilation*