OBJECTIVETo investigate the influence of high frequency partial liquid ventilation (HFJV) on the cardiopulmonary function in dogs with inhalation injury.

METHODSSixteen mongrel dogs inflicted by hot steam inhalation were subjected to severe inhalation injury and were randomly divided into control (C) and treatment (T) groups. The dogs in both groups were all given HFJV. In addition, the dogs in T group were simultaneously supplied with perfluorocarbon liquid (3 ml/kg) into the lungs slowly via tracheal intubation for liquid ventilation. The blood gas analysis, pulmonary compliance, airway resistance and hemodynamic parameters were determined at 30, 60 and 90 minutes after ventilation.

RESULTSThe PaO(2) in T group increased progressively, which was significantly higher than the post-injury value at all time points (P < 0.05). While the PaO(2) in C group exhibited no difference to the post-injury value at all time points. The PaCO(2) in T group increased obviously and was higher than the post-injury value at 60 and 90 post-ventilation minutes (P < 0.05). Furthermore, the PaO(2) in all the time points in T group was a little higher than that in C group (P > 0.05) and PaCO(2) in T group was much higher than that in C group at 90 min after ventilation (P < 0.05). But there was no difference between the two groups in terms of dynamic/static pulmonary compliance and airway resistance as well as the hemodynamics.

CONCLUSIONCompared with simple HFJV, high frequency partial liquid ventilation seemed to be beneficial to the oxygenation after inhalation injury and to be no influence on the hemodynamics.

Airway Resistance ; Animals ; Blood Gas Analysis ; Burns, Inhalation ; physiopathology ; therapy ; Dogs ; Female ; High-Frequency Jet Ventilation ; Liquid Ventilation ; Lung Compliance ; Male ; Pulmonary Circulation ; Pulmonary Gas Exchange ; Respiration, Artificial ; methods ; Respiratory Function Tests ; Time Factors

OBJECTIVES: The effectiveness of the active humidification systems (AHS) in patients already weaned from mechanical ventilation and with an artificial airway has not been very well described. The objective of this study was to evaluate the performance of an AHS in chronically tracheostomized and spontaneously breathing patients. METHODS: Measurements were quantified at three levels of temperature (Tdegrees) of the AHS: level I, low; level II, middle; and level III, high and at different flow levels (20 to 60 L/minute). Statistical analysis of repeated measurements was performed using analysis of variance and significance was set at a P<0.05. RESULTS: While the lowest temperature setting (level I) did not condition gas to the minimum recommended values for any of the flows that were used, the medium temperature setting (level II) only conditioned gas with flows of 20 and 30 L/minute. Finally, at the highest temperature setting (level III), every flow reached the minimum absolute humidity (AH) recommended of 30 mg/L. CONCLUSION: According to our results, to obtain appropiate relative humidity, AH and Tdegrees of gas one should have a device that maintains water Tdegrees at least at 53degrees C for flows between 20 and 30 L/m, or at Tdegrees of 61degrees C at any flow rate.
Humans ; Humidity ; Oxygen Inhalation Therapy ; Patient Care ; Respiration ; Respiration, Artificial ; Respiratory Therapy ; Tracheostomy ; Ventilator Weaning ; Water

OBJECTIVE: To study the safety of two ventilator weaning strategies after high-frequency oscillatory ventilation (HFOV) for the treatment of neonatal respiratory distress syndrome (NRDS) in preterm infants. METHODS: A prospective randomized controlled trial was conducted for 101 preterm infants with NRDS, with a gestational age of ≤32 RESULTS: There was no significant difference in the failure rate of ventilator weaning within 72 hours (8% vs 14%, CONCLUSIONS For preterm infants with NRDS, the strategy of weaning directly from HFOV is safe and reliable and can reduce the duration of invasive mechanical ventilation, and therefore, it holds promise for clinical application.
High-Frequency Ventilation ; Humans ; Infant, Newborn ; Infant, Premature ; Prospective Studies ; Respiration, Artificial ; Respiratory Distress Syndrome, Newborn/therapy* ; Ventilator Weaning

PURPOSE: Repair of congenital diaphragmatic hernias (CDH) has changed from an urgent procedure to a delayed procedure during the last decade. Recently, several new therapeutic methods have been suggested, such as extracorporeal membrane oxygenation, high frequency oscillatory ventilation, partial liquid ventilation, nitric oxide (NO) inhalation, surfactant therapy, and fetal tracheal ligation. Despite recent approaches, CDH remains an unsolved problem with a mortality rate of 35% to 50%. We evaluated the clinical manifestations and the outcomes of newborns that had a Bochdalek hernia. METHODS: The charts of all neonates with a Bochdalek hernia who had been treated at the Division of Pediatric Surgery, Asan Medical Center, from May 1989 to December 1999 were reviewed (n=32). The following para meters were analyzed for survival; gestational age, birth weight, the presence of associated anomalies, the side of defect, the presence of a sac, the position of the stomach, the age at surgery, the availability of high frequency ventilation therapy, and the availability of NO inhalation therapy (1998-1999). RESULTS: Overall, 20 of the 32 newborns survived (62.5%). The average age at gestation was 269 days (range: 202 to 288 days). The average weight at birth was 2,800 gram (range: 856-4,000 grams). There were seven major anomalies. Six patients died without repair. The average age at repair was 39.8 hours (range: 0.5 to 168 hours). The defect was left sided in 23 cases (88.5%). Four had hernia sacs. The stomach had herniated into the chest in 7 of 26 cases. Since 1998, the survival rate has been 7/10 (70.0%). The significant prognostic factors were birth weight and the presence of major anomalies (p<0.05). CONCLUSION: Birth weight and the presence of major anomalies had a significant effect on survival. In neonates with CDH, and careful long-term follow up is required to evaluate strategies using high frequency ventilation and inhaled NO.
Birth Weight ; Chungcheongnam-do ; Extracorporeal Membrane Oxygenation ; Gestational Age ; Hernia* ; Hernia, Diaphragmatic ; High-Frequency Ventilation ; Humans ; Infant, Newborn* ; Inhalation ; Ligation ; Liquid Ventilation ; Mortality ; Nitric Oxide ; Parturition ; Pregnancy ; Respiratory Therapy ; Stomach ; Survival Rate ; Thorax ; 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

Combined Modality Therapy ; High-Frequency Ventilation ; Humans ; Liquid Ventilation ; Nitric Oxide ; therapeutic use ; Pulmonary Surfactants ; therapeutic use ; Respiration, Artificial ; Respiratory Insufficiency ; therapy

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

BACKGROUNDHigh-frequency oscillatory ventilation (HFOV) allows for small tidal volumes at mean airway pressures (mPaw) above that of conventional mechanical ventilation (CMV), but the effect of HFOV on hemodynamics, oxygen metabolism, and tissue perfusion in acute respiratory distress syndrome (ARDS) remains unclear. We investigated the effects of HFOV and CMV in sheep models with ARDS.

METHODSAfter inducing ARDS by repeated lavage, twelve adult sheep were randomly divided into a HFOV or CMV group. After stabilization, standard lung recruitments (40 cmH2O × 40 seconds) were performed. The optimal mPaw or positive end-expiratory pressure was obtained by lung recruitment and decremental positive end-expiratory pressure titration. The animals were then ventilated for 4 hours. The hemodynamics, tissue perfusion (superior mesenteric artery blood flow, pHi, and Pg-aCO2), oxygen metabolism and respiratory mechanics were examined at baseline before saline lavage, in the ARDS model, after model stabilization, and during hourly mechanical ventilation for up to 4 hours. A two-way repeated measures analysis of variance was applied to evaluate differences between the groups.

RESULTSThe titrated mPaw was higher and the tidal volumes lower in the HFOV group than the positive end-expiratory pressure in the CMV group. There was no significant difference in hemodynamic parameters between the HFOV and CMV groups. There was no difference in the mean alveolar pressure between the two groups. After lung recruitment, both groups showed an improvement in the oxygenation, oxygen delivery, and DO2. Lactate levels increased in both groups after inducing the ARDS model. Compared with the CMV group, the superior mesenteric artery blood flow and pHi were significantly higher in the HFOV group, but the Pg-aCO2 decreased in the HFOV group.

CONCLUSIONCompared with CMV, HFOV with optimal mPaw has no significant side effect on hemodynamics or oxygen metabolism, and increases gastric tissue blood perfusion.

Animals ; Disease Models, Animal ; Hemodynamics ; physiology ; High-Frequency Ventilation ; methods ; Male ; Oxygen ; metabolism ; Positive-Pressure Respiration ; methods ; Respiration, Artificial ; methods ; Respiratory Distress Syndrome, Adult ; metabolism ; therapy ; Sheep

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