BACKGROUND: The use of positive end expiratory pressure (PEEP) in patients with acute lung injury (ALI) improves arterial oxygenation by alleviating pulmonary shunting, helping the respiratory muscles to decrease the work of breathing, decreasing the rate of infiltrated and atelectatic tissues, and increasing functional residual capacity. In a rabbit model of saline lavage-induced ALI, we examined the effects of PEEP on gas exchange, hemodynamics, and oxygenation during high frequency jet ventilation (HFJV), and then compared these parameters with those during conventional mechanical ventilation (CMV). METHODS: Twelve rabbits underwent repeated saline lavage to create ALI. The animals were divided in 2 groups: 1) Group CMV (n = 6), and 2) Group HFJV (n = 6). In both groups, we applied 2 levels of PEEP (5 cmH2O and 10 cmH2O) and then measured the arterial blood gas, mixed venous blood gas, and hemodynamic parameters. RESULTS: With administration of PEEP of either 5 cmH2O or 10 cmH2O, the arterial oxygen content of both groups was increased, although without statistically significant differences between groups. On the contrary, the arterial carbon dioxide content was significantly decreased in the HFJV group, as compared with the CMV group, during the entire experiment. Furthermore, there was significant decreases in mean arterial pressures in both groups with a PEEP of 10 cmH2O. CONCLUSIONS: The application of PEEP in rabbits with ALI effectively improves oxygenation in either HFJV or CMV.
Acute Lung Injury ; Animals ; Arterial Pressure ; Carbon Dioxide ; Functional Residual Capacity ; Hemodynamics ; High-Frequency Jet Ventilation ; Humans ; Oxygen ; Positive-Pressure Respiration ; Rabbits ; Respiration, Artificial ; Respiratory Muscles ; Therapeutic Irrigation ; Work of Breathing

No abstract available.
Positive-Pressure Respiration* ; Respiration, Artificial ; Weaning*

No abstract available.
Positive-Pressure Respiration* ; Respiration, Artificial ; Weaning*

BACKGROUND: It is invasive and accompanies various risks to insert pulmonary artery catheter in order to measure mixed venous oxygen saturation (SvO2) that is associated with patients clinical course and prognosis. If there is relationship between central venous oxygen saturation (ScvO2) and mixed venous oxygen saturation, we can use the central venous oxygen saturation instead of mixed venous oxygen saturation to monitor and treat patients. METHODS: We inserted the Swan-Ganz catheter in 20 patients (male 8, female l2) scheduled for undergoing open heart surgery and accomplished the blood gas analysis of the radial arterial blood, central venous blood and mixed venous blood during postoperative respiratory care in intensive care unit at F1O2 1.0, 0.6 and 0.4 in order. RESULTS: There was no significant difference between central venous blood and mixed venous blood in respect to pH, PCO2, PO2. except the mixed venous blood pH at F1O2 0.6 that is greater than the central venous blood pH at F1O2 0.6. Central venous oxygen saturation and mixed venous saturation were not significantly different and showed the following close relationship: SvO2(%)=15.41+0.80XScvO2 (R=0.88, p<0.05). In respect to the difference according to the variation of F1O2, the SO2 and PO2 at F1O2. 1.0 were higher than the SO2 and PO2 at F1O2 0.6 and 0.4, but the differnce between F1O2 0.6 and 0.4 was not significant. CONCLUSIONS: We might conclude that central venous oxygen saturation might be replaced for the mixed venous oxygen saturation in respiratory care after open heart surgery in adults.
Adult ; Blood Gas Analysis ; Catheters ; Female ; Humans ; Hydrogen-Ion Concentration ; Intensive Care Units ; Intermittent Positive-Pressure Breathing ; Oxygen* ; Prognosis ; Pulmonary Artery ; Respiration, Artificial* ; Thoracic Surgery ; 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: Noninvasive ventilation has been used extensively for the treatment of patients with neuromuscular weakness or restrictive chest wall disorders complicated by hypoventilatory respiratory failure. Recently, noninvasive positive pressure ventilation has been used in patients with alveolar hypoventilation,chronic obstructive pulmonary disease(COPD),and adult respiratory distress syndrome. Sanders and Kern reported treatment of obstructive sleep apnea with a modification of the standard nasal CPAP device to deliver seperate inspiratory positive airway pressure(IPAP) and expiratory positive airway pressure(EPAP).Bi-level positive airway pressure (BiPAP) unlike nasal CPAP, the unit delivers a different pressure during inspiration from that during expiration The device is similar to the positive pressure ventilator or pressure support ventilation. METHOD AND PURPOSE: Bi-level positive airway pressure(BiPAP) system(Respironics, USA) was applied to seven patients with acute respiratory failure and three patients on conventional mechanical ventilation. RESULTS: 1) Two of three patients after extubation were successfully achieved weaning from conventional mechanical ventilation by the use of BiPAP ventilation with nasal mask. Five of seven patients with acute respiratory failure successfully recovered without use of conventional mechanical ventilation. 2) PaO2 lhour after BiPAP ventilation in acute respiratory failure patients significantly improved more than baseline values(p<0.01)). PaCO2 lhour after BiPAP ventilation in acute respiratory failure patients did not change significantly more than baseline values. CONCLUSION: Nasal mask BiPAP ventilation can be one of the possible alternatives of conventional mechanical ventilation in acute respiratory failure and supportive method for weaning from mechanical ventilation.
Humans ; Intermittent Positive-Pressure Ventilation* ; Masks ; Noninvasive Ventilation ; Positive-Pressure Respiration ; Respiration, Artificial ; Respiratory Distress Syndrome, Adult ; Respiratory Insufficiency ; Sleep Apnea, Obstructive ; Thoracic Wall ; Ventilation ; Ventilators, Mechanical ; Weaning

PURPOSE: Early surfactant therapy with either gentle ventilation, high-frequency ventilation or aggressive weaning of mechanical ventilation are principles for the treatment of respiratory distress syndrome(RDS). We studied to determine the accessibility of noninvasive nasal continuous positive airway pressure(CPAP) rather than mechanical ventilation by invasive intubation after early surfactant therapy. METHODS: The study group consisted of 14 infants who were born and diagnosed with moderate respiratory distress syndrome and received early surfactant therapy with nasal CPAP of PEEP 5-6 cm H2O within two hours after birth in the Fatima neonatal intensive care unit for two years from January 1999 to August 2001. The control group consisted of 15 infants who were diagnosed with the disease and could be weaned from mechanical ventilator within five days after birth during the same period. RESULTS: The characteristics, the severity of clinical symptoms and laboratory findings in the two groups at birth showed no significant difference. Neither did the interim analysis of laboratory data in two groups. Of 14 infants in the study group who received nasal CPAP after early surfactant therapy, only two infants showed weaning failure with this therapy. In the response cases, duration of CPAP was five days and mean airway pressure was 5.4+/-0.5 cm H2O. Two had the complication of CPAP with abdominal distension. Final complications and outcomes in the two groups showed no signifcant difference(p>0.05). CONCLUSION: The clinical courses in the two groups showed no significant difference. Therefore, we suggest that early surfactant therapy with noninvasive nasal CPAP is a simple and safe method rather than aggressive weaning after invasive mechanical ventilation in moderate respiratory distress syndrome.
Continuous Positive Airway Pressure* ; High-Frequency Ventilation ; Humans ; Infant ; Infant, Newborn ; Intensive Care, Neonatal ; Intubation ; Parturition ; Respiration, Artificial ; Ventilation ; Ventilators, Mechanical ; Weaning

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

OBJECTIVETo evaluate the effects of different interventional strategies, namely controlled high-concentration oxygen therapy, continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP) ventilation, on respiratory response and work of breathing (WOB) in canine models of early-stage acute lung injury (ALI).

METHODSAfter successful duplication of ALI models with oleic acid (diagnostic criteria: Pa(O2)/Fi(O2)high-concentration oxygen therapy (O2), CPAP, and BiPAP, respectively. The parameters of respiratory response and WOB were recorded continuously at the baseline, early-stage ALI, and 1-4 hours after treatment.

RESULTSBiPAP resulted in the most significant effects in reducing the respiratory rate (RR) and f/V(T) (P<0.001), followed by CPAP and O2 interventions (P<0.001). None of the 3 treatments showed obvious effects on V(E) (P>0.05), which maintained the level of early ALI/ARDS stage. BiPAP greatly improved V(T) and V(T)/Ti, showing better effects than CPAP and O2. No significant differences were noted among the 3 groups in T(I)/T(tot) (P>0.05). BiPAP showed superior effect to CPAP in lowering the peak transdiaphragmatic pressure (Pdi). CPAP and BiPAP both effectively counteracted intrinsic positive end expiratory pressure (PEEPi) (P<0.01), while O2 produced no obvious such effects (P>0.05). BiPAP showed the most evident effects, followed by CPAP, in reducing WOB, but oxygen therapy produced no obvious effects. CPAP (P<0.01) and BiPAP (P>0.05) both effectively reduced the proportion of ingredients in WOB related to PEEPi.

CONCLUSIONBiPAP and CPAP can produce favorable effects in relieving dyspnea, reducing WOB and improving respiratory response to control the deterioration of ARDS. BiPAP has more significant therapeutic effects than CPAP and oxygen therapy.

Acute Disease ; Animals ; Continuous Positive Airway Pressure ; Dogs ; Female ; Lung Diseases ; physiopathology ; therapy ; Male ; Oxygen Inhalation Therapy ; Positive-Pressure Respiration ; Respiration ; Respiration, Artificial ; methods ; Time Factors

The selection of either conventional mechanical ventilation or HFJV depends on the physical status of the patient,potential physioloic advantages and disadvantages, the requirements of the clinical situation and the capability of providing adequate oxygenation and ventilation. We have experienced that HFJV markedly improved the ventilatory status of a 52-year old male patient with severe respiratory failure due to flail chest and ruptured giant bulla refractory to conventional mechanical ventilatory support.
Anoxia* ; Flail Chest ; High-Frequency Jet Ventilation ; Humans ; Male ; Middle Aged ; Oxygen ; Respiration, Artificial* ; Respiratory Insufficiency ; Ventilation