[New techniques of mechanical ventilation: liquid ventilation and partial liquid ventilation].
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Humans↗
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Results for “Liquid Ventilation”
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Liquid ventilation.
Liquid ventilation (LV) is an exciting, up-and-coming technique presently under investigation for the treatment of acute respiratory distress syndrome (ARDS) and infantile respiratory distress syndrome (IRDS). Two different methods of LV, total liquid ventilation (TLV) and partial liquid ventilation (PLV), are described in this article using a liquid called perflubon. This type of therapy has been shown to positively affect the physiologic derangements seen in ARDS and IRDS cases, and may have additional benefits, including anti-inflammatory properties and synergistic characteristics with other known and experimental therapies.
Adult↗
Oxygen consumption and carbon dioxide production during liquid ventilation.
Liquid ventilation with perfluorocarbon (PFCV) has advantages over conventional gas ventilation (GV) in premature and lung-injured newborn animals. Indirect calorimetric measurement of both oxygen consumption (VO2) and carbon dioxide production (VCO2) during PFCV has not been previously performed. In addition, comparison to indirect calorimetric measurement of VO2 and VCO2 during GV has not been evaluated. Ten fasted normal cats weighing 2.6 to 3.9 kg were anesthetized with pentobarbital and pancuronium. Tracheostomy was performed. Gas exchange was measured across the native lung during GV and across the membrane lung of the liquid ventilator during PFCV. VO2 was measured using a modification of a previously described, indirect, closed-circuit, volumetric technique. VCO2 was analyzed by capnographic assay of the mixed-expired closed-circuit air. The VCO2/VO2 ratio (RQ) was calculated. There was no change in VO2, VCO2, or RQ during PFCV when compared with GV (VO2: GV = 5.7 +/- 0.3 mL/kg/min, PFCV = 5.6 +/- 0.5 mL/kg/min [P = NS]; VCO2: GV = 4.9 +/- 1.1 mL/kg/min, PFCV = 4.8 +/- 0.9 mL/kg/min [P = NS]; RQ: GV = 0.85 +/- 0.21, PFCV = 0.86 +/- 0.21 [P = NS]). During GV the PaO2 was higher than during PFCV (PaO2: GV = 335 +/- 70 mm Hg, PFCV = 267 +/- 83 mm Hg [P = .04]), as is expected because of the relative reduction in the inspiratory PiO2 of the perfluorocarbon during liquid ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Liquid ventilation.
Liquid breathing has been proposed as a means of improving gas exchange in infants with acute respiratory failure since the 1970s. In addition, there are potential clinical applications of perfluorochemical (PFC) liquids that span many specialties in medicine. The ability to lower surface tension directed the initial clinical focus on neonatal therapy in the treatment of premature lung disease. The first clinical trial of PFC ventilation was performed in neonates in 1989. Additional trials using LiquiVent (Alliance Pharmaceutical San Diego, CA), a medical grade PFC liquid, were initiated in 1993 in infants, children, and adults. These studies have concluded that liquid ventilation appeared to be safe, improve lung function, and recruit lung volume in patients from these populations. The results of such trials are encouraging, but randomized trials have yet to be completed. We await these pivotal trials, which will probably be completed in adult patients first, before this promising technique can be clinically available.
Clinical Trials as Topic↗
High-frequency oscillatory ventilation, partial liquid ventilation, or conventional mechanical ventilation in newborn piglets with saline lavage-induced acute lung injury. A comparison of gas-exchange efficacy and lung histomorphology.
It has been reported that, in diseased lungs, either partial liquid ventilation (PLV) or high-frequency oscillatory ventilation (HFOV) can improve oxygenation better and with less lung injury than conventional mechanical ventilation (CMV). This study was intended as a preclinical comparison between the effects of HFOV, PLV and CMV on gas exchange, lung mechanics and histology. Fifteen anesthetized newborn piglets, with respiratory insufficiency due to repeated saline lung lavage, were allocated to either a PLV, HFOV or CMV (n = 5 each) strategy, and treated for 4 h. Within 30 min of commencing therapy, PLV, HFOV, and CMV improved arterial PO2 (Pa,O2), alveoloarterial oxygen gradient (P(A-a),O2), oxygenation index (OI), venous admixture (va), and arterial PCO2 (Pa,CO2). After 4 h, oxygenation parameters (Pa,O2, P(A-a),O2, OI and venous admixture) were significantly better in the HFOV group than in the PLV group; the CMV group showed a higher Pa,O2 and lower OI than the PLV group. Gas exchange at the end of the experiment was not different from baseline in the HFOV and CMV groups. Lung histology and morphometry were performed after perfusion-fixation at endotracheal deflation pressure corresponding to mean airway pressure at the end of the experiment. Lung injury score and mean linear intercept were not different between the three treatment groups. We conclude that in this model, gas exchange improved significantly in all three ventilation strategies. Indices of oxygenation improved less during PLV. The saline lavage-induced acute lung injury model used as in this study, is less stable than previously thought. The final lung injury is not influenced by the ventilation strategy. We speculate that the impaired gas exchange during PLV is an expression of diffusion limitation and ventilation-perfusion mismatch in a recovering lung.
Animals↗
High-frequency oscillatory ventilation and partial liquid ventilation: liquid breathing to a different beat (frequency)
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Animals↗
Non-conventional respiratory support modalities applicable in the older child. High frequency ventilation and liquid ventilation.
HFV, LV, and several other novel therapies offer promise to adults and children that the mortality associated with respiratory failure may be affected. Although there are several forms of HFV, HFOV is presently gaining favor in the treatment of severe respiratory failure and has generally supplanted HFJV in pediatric critical care. HFOV has the advantage of having an active expiratory phase, which helps to minimize air trapping and better modulate mean lung volume. Ventilators with sufficient power to perform HFOV in adults are currently under investigation, although there is a growing experience in using current ventilators in larger patients. To date, however, demonstration of lowered mortality with HFOV is lacking although intermediate outcome indicators are improved. PLV also offers promise in the treatment of ARF through its drastic ability to improve oxygenation, ventilation, and compliance in many lung injury models. Human trials are presently underway, but the optimal delivery of this novel therapy still necessitates extensive investigation. TLV is likely even more removed from general clinical application given the necessity of developing a new generation of ventilators for the delivery of liquid tidal volumes. How these and other modalities may piece together to improve the condition of our patients who have respiratory failure remains to be seen, but certainly, present and future investigation will be intriguing for years to come.
Acute Disease↗
Optimizing liquid ventilation as a lung protection strategy for neonatal cardiopulmonary bypass: full functional residual capacity dosing is more effective than half functional residual capacity dosing.
OBJECTIVE: To evaluate and compare the protective effects of two different perflubron doses on hemodynamics and lung function in a neonatal animal model of cardiopulmonary bypass-induced lung injury. DESIGN: Prospective, randomized, controlled study. SETTING: Animal laboratory of the Department of Surgery, Duke University Medical Center. SUBJECTS: Twenty-one neonatal swine. INTERVENTIONS: One-wk-old swine (2.2-3.2 kg) were randomized to receive cardiopulmonary bypass with full functional residual capacity perflubron (n = 7), cardiopulmonary bypass with half functional residual capacity perflubron (n = 7), or cardiopulmonary bypass alone (n = 7). This last group served as control animals, receiving cardiopulmonary bypass with conventional ventilation. Liquid lung ventilation animals received perflubron via the endotracheal tube at either full functional residual capacity (16-20 mL/kg) or half functional residual capacity (10 mL/kg) before the initiation of cardiopulmonary bypass. Each animal was placed on nonpulsatile cardiopulmonary bypass and cooled to a nasopharyngeal temperature of 18 degrees C (64.4 degrees F). Low-flow cardiopulmonary bypass (35 mL/kg/min) was instituted for 90 mins. The blood flow rate was then returned to 100 mL/kg/min. The animals were warmed to 36 degrees C (96.8 degrees F) and separated from cardiopulmonary bypass. Data were obtained at 30, 60, and 90 mins after separation from cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: Cardiopulmonary bypass without liquid lung ventilation resulted in a significant decrease in cardiac output and oxygen delivery and a significant increase in pulmonary vascular resistance in the post-bypass period. Full functional residual capacity liquid lung ventilation administered before bypass resulted in no change in cardiac output and oxygen delivery after bypass. Full functional residual capacity liquid lung ventilation resulted in lower pulmonary vascular resistance after bypass compared with both control and half functional residual capacity liquid lung ventilation animals. CONCLUSIONS: These data suggest that liquid lung ventilation dosing at full functional residual capacity before bypass is more effective than half functional residual capacity in minimizing the lung injury associated with neonatal cardiopulmonary bypass. Full functional residual capacity dosing may optimize alveolar distention and lung volume, as well as improve oxygen delivery compared with half functional residual capacity dosing.
Analysis of Variance↗
A perfluorochemical loss/restoration (L/R) system for tidal liquid ventilation.
Tidal liquid ventilation is the transport of dissolved respiratory gases via volume exchange of perfluorochemical (PFC) liquid to and from the PFC-filled lung. All gas-liquid surface tension is eliminated, increasing compliance and providing lung protection due to lower inflation pressures. Tidal liquid ventilation is achieved by cycling fluid from a reservoir to and from the lung by a ventilator. Current approaches are microprocessor-based with feedback control. During inspiration, warmed oxygenated PFC liquid is pumped from a fluid reservoir/gas exchanger into the lung. PFC fluid is conserved by condensing (60-80% efficiency) vapor in the expired gas. A feedback-control system was developed to automatically replace PFC lost due to condenser inefficiency. This loss/restoration (L/R) system consists of a PFC-vapor thermal detector (+/- 2.5%), pneumatics, amplifiers, a gas flow detector (+/- 1%), a PFC pump (+/- 5%), and a controller. Gravimetric studies of perflubron loss from a flask due to evaporation were compared with experimental L/R results and found to be within +/- 1.4%. In addition, when L/R studies were conducted with a previously reported liquid ventilation system over a four-hour period, the L/R system maintained system perflubron volume to within +/- 1% of prime volume and 11.5% of replacement volume, and the difference between experimental PFC loss and that of the L/R system was 1.8 mL/hr. These studies suggest that the PFC L/R system may have significant economic (appropriate dosing for PFC loss) as well as physiologic (maintenance of PFC inventory in the lungs and liquid ventilator) impact on liquid ventilation procedures.
Calibration↗
Development of a time-cycled volume-controlled pressure-limited respirator and lung mechanics system for total liquid ventilation.
Total liquid ventilation can support gas exchange in animal models of lung injury. Clinical application awaits further technical improvements and performance verification. Our aim was to develop a liquid ventilator, able to deliver accurate tidal volumes, and a computerized system for measuring lung mechanics. The computer-assisted, piston-driven respirator controlled ventilatory parameters that were displayed and modified on a real-time basis. Pressure and temperature transducers along with a lineal displacement controller provided the necessary signals to calculate lung mechanics. Ten newborn lambs (<6 days old) with respiratory failure induced by lung lavage, were monitored using the system. Electromechanical, hydraulic, and data acquisition/analysis components of the ventilator were developed and tested in animals with respiratory failure. All pulmonary signals were collected synchronized in time, displayed in real-time, and archived on digital media. The total mean error (due to transducers, analog-to-digital conversion, amplifiers, etc.) was less than 5% compared with calibrated signals. Components (tubing, pistons, etc.) in contact with exchange fluids were developed so that they could be readily switched, a feature that will be important in clinical settings. Improvements in gas exchange and lung mechanics were observed during liquid ventilation, without impairment of cardiovascular profiles. The total liquid ventilator maintained accurate control of tidal volumes and the sequencing of inspiration/expiration. The computerized system demonstrated its ability to monitor in vivo lung mechanics, providing valuable data for early decision making.
Analysis of Variance↗
A comparison of surfactant delivery with conventional mechanical ventilation and partial liquid ventilation in meconium aspiration injury.
The objective of this study was to compare surfactant (SF) distribution and physiological effects after standard SF delivery during conventional mechanical ventilation (CMV) with that using partial liquid ventilation (PLV). A model of meconium aspiration syndrome (MAS) was developed using two groups of adult rats (n = 14). After meconium instillation of 2.5 ml kg(-1) (20% v/w), SF/CMV: (n = 7) CMV and SF/PLV: (n = 7) PLV, received 14C-labeled surfactant (4 ml kg(-1)) delivered intratracheally in four aliquots over 20 min in both groups. Sequential measurements of arterial blood chemistry and lung mechanics were performed in all animals. At the conclusion of experiments, lungs were inflated (30 cmH2O), dried, sectioned and evaluated for radioactivity in disintegrations per minute (DPM). Surfactant distribution was improved (P< 0.01) with PLV as compared to CMV with 48.8% of the pieces vs. 30.9% of the pieces receiving within 25% of the mean amount of surfactant, respectively. Further, regional distribution was also significantly more uniform with PLV than CMV: left vs right (P<0.01) lung and ventral vs. dorsal (P<0.01) regions. Finally, arterial PO2 and ventilation efficiency index were significantly (P<0.01) greater post-treatment in SF/PLV than SF/CMV. These data demonstrate surfactant delivery with PLV, as compared to CMV alone, to be an improved method of delivering surfactant in MAS and suggest the possible utility of SF/PLV combination therapy for its treatment of other etiologies of neonatal respiratory distress.
Analysis of Variance↗
Physiologic, biochemical, and histologic correlates associated with tidal liquid ventilation.
Tidal liquid ventilation (TLV) with perfluorochemical fluid (PFC) has been successfully used experimentally for up to 4 h. However, no studies of prolonged TLV have been reported. We hypothesized that full-term newborn lambs can safely and effectively be liquid-ventilated for up to 24 h. To test this hypothesis, 17 lambs were liquid-ventilated; 7 for 4 h, 5 for 12 h, and 5 for 24 h. Arterial blood samples were obtained for PFC uptake, lipid analysis, and blood gas measurements. Tissues were obtained for histologic and biochemical analysis. Arterial blood gas and mean arterial blood pressure were as follows (mean +/- SEM): pH 7.48 +/- 0.04; PaCO2 30.6 +/- 2.8; PaO2 424 +/- 17; mean arterial pressure 76 +/- 16 mm Hg. PFC blood levels increased rapidly to a mean of 5.2 +/- 3.9 microg/mL. PFC tissue levels increased significantly (p < 0.01) from 260 +/- 45 microg/g at 4 h to 400 +/- 140 microg/g at 12 h. There was no further increase in PFC tissue levels by 24 h (456 +/- 181 microg/g). There was a significant difference in PFC concentration as a function of tissue (p < 0.01). Furthermore, there was a significant correlation (r = 0.88; p < 0.01) between the amount of PFC and lipid in blood and tissue. Microscopic examination of the lungs demonstrated no evidence of barotrauma. These data demonstrate that prolonged TLV can be safe and efficacious for up to 24 h in full-term newborn lambs.
Animals↗
Pneumomediastinum: elucidation of the anatomic pathway by liquid ventilation.
Partial liquid ventilation is a new technique to improve oxygenation in patients with severe acute respiratory distress syndrome. In a patient with status asthmaticus and tension pneumothorax treated with subsequent liquid ventilation, radiopaque perfluorocarbon was identified along brochiovascular structures, in the mediastinum, and in the retroperitoneum. Perfluorocarbon outlined on CT and chest radiography the anatomic pathway by which spontaneous pneumomediastinum develops following alveolar rupture, as described earlier by histopathologic study in animals. This represents the radiopaque equivalent of radiolucent pneumomediastinum. Perfluorocarbon remained in the pulmonary interstitium on radiography 30 days after beginning liquid ventilation, without sequelae.
Adult↗
High-frequency oscillatory ventilation and partial liquid ventilation after acute lung injury in premature lambs with respiratory distress syndrome.
OBJECTIVE: Conventional mechanical ventilatory support (CV) contributes to lung injury in premature lambs with respiratory distress syndrome, a disease that is characterized by progressive deterioration of gas exchange and increased lung inflammation. Lung recruitment strategies, such as high-frequency oscillatory ventilation (HFOV) and partial liquid ventilation (PLV), improve gas exchange and attenuate lung inflammation when instituted immediately after birth. However, whether these recruitment strategies are effective as rescue treatment after established lung injury is unknown. To determine the separate and combined effects of HFOV and PLV when initiated after the establishment of acute lung injury in severe respiratory distress syndrome, we studied the effects of these strategies on gas exchange and histologic signs of acute lung injury in premature lambs. DESIGN: Animals were intubated, treated with surfactant and ventilated with 1.00 FIO2 for 4 hrs. After 2 hrs, animals were either continued on CV (controls) or treated with one of three strategies: HFOV; CV + PLV; or HFOV + PLV. The response to low-dose inhaled nitric oxide (5 ppm) was measured in each group at the end of the study. SETTING: An animal laboratory affiliated with University of Colorado School of Medicine. SUBJECTS: A total of 20 premature lambs at 115-118 days of gestation (term = 147 days). MEASUREMENTS AND MAIN RESULTS: In comparison with control animals, each of the rescue therapies improved PaO2 after 1 hr of treatment. The HFOV and HFOV + PLV groups had higher PaO2 than CV + PLV or CV alone (p < .05). Mean airway pressure (Paw) was lower in the PLV groups during CV or HFOV compared with their controls (p < .05). Inhaled NO improved PaO2 in all groups; however, the increase in PaO2 was greatest in the HFOV + PLV group (p < .05). Histologic examination and myeloperoxidase assay were not different between groups. CONCLUSION: We conclude that each lung recruitment strategy improved oxygenation in premature lambs with established lung injury.
Algorithms↗
Pressure- versus volume-cycled ventilation in liquid-ventilated neonatal piglet lungs.
BACKGROUND/PURPOSE: If the goal of partial liquid ventilation (PLV) with perfluorocarbons in the management of respiratory failure is to improve dynamic lung compliance (Cdyn) and pulmonary vascular resistance (PVR) while sustaining O2 delivery, the optimal ventilatory management is unclear. The authors asked if volume-cycled or pressure-limited ventilation had different effects on PVR, cardiac index (CI), and Cdyn in uninjured and injured neonatal piglet lungs. METHODS: Anesthetized piglets (6 to 8 kg) were ventilated after tracheostomy. Cdyn was measured by in-line Fleisch pneumotach/PC data acquisition terminal. Thermodilution instrumentation allowed determination of both CI and PVR. Volume-control or pressure-limited ventilation was established in uninjured or injured (surfactant deficiency induced by saline lavage at 18 mL/kg) animals. After a stable 30-minute baseline, animals were assigned randomly to one of four groups: group I (n = 9), uninjured animals plus volume-cycled ventilation (intermittent mandatory ventilation [IMV], 10 bpm; tidal volume [TV], 15 mL/kg, positive end-expiratory pressure [PEEP], 5 cm H2O; FIO2, 1.0; and PLV for 150 minutes); group II (n = 9), uninjured animals plus pressure-limited ventilation (IMV, 10 bpm; peak inspiratory pressure (PIP), 25 cm H2O, PEEP, 5 cm H2O, FIO2, 1.0; and PLV for 150 minutes); group III (n = 7), injured animals plus volume-cycled ventilation (IMV, 10 bpm; TV, 15 mL/kg; PEEP, 5 cm H2O; FIO2, 1.0 for 30 minutes, followed by saline injury for group IV (n = 7), injured animals plus pressure-limited ventilation (IMV, 10 bpm; PIP, 25 cm H2O; PEEP, 5 cm H2O; FIO2, 1.0 for 30 minutes, followed by saline injury, and PLV rescue). Comparison within and between groups was accomplished by repeated measures analysis of variance (ANOVA) with Tukey correction. RESULTS: There was no significant difference between volume-cycled or pressure-limited ventilation in healthy lungs; however, in the setting of lung injury, dynamic compliance was 1.44 +/- 0.15 after 180 minutes in the volume-cycled group and 0.91 +/- 0.10 in the pressure-limited group after the same interval (mL/cm H2O x kg +/- SEM). Similarly, PVR was 100 +/- 6 in the volume-cycled group and 145 +/- 12 in the pressure-limited group after 180 minutes of lung injury (mm Hg/L/kg x min +/- SEM). Cardiac index declined significantly in all groups independent of ventilatory mode. CONCLUSIONS: These results suggest that in the setting of lung injury, Cdyn and PVR improved significantly when volume-cycled, compared with pressure-limited ventilation was used. Although no difference existed between ventilatory modes in healthy lungs, pressure-limited ventilation, when combined with PLV in injured lungs, had adverse effects on lung compliance and pulmonary vascular resistance. Volume-cycled ventilation may optimize the ability of perfluorocarbon to recruit collapsed or atelectatic lung regions.
Analysis of Variance↗
Development and application of a simplified liquid ventilator.
OBJECTIVE: Perfluorocarbon liquid ventilation has been shown to have advantages over conventional gas ventilation in premature newborn and lung-injured animals. To simplify the process of liquid ventilation, we adapted an extra-corporeal life-support circuit as a time-cycled, volume-limited liquid ventilator. DESIGN: Laboratory study that involved sequential application of gas and liquid ventilation in normal cats and in lung-injured sheep. SETTING: A research laboratory at a university medical center. SUBJECTS: Eight normal cats weighing 2.7 to 3.8 kg (mean 3.1 +/- 0.5), and four lung-injured young sheep weighing 10.4 to 22.5 kg (mean 15.9 +/- 5.0). INTERVENTIONS: Normal cats were supported with traditional gas ventilation for 1 hr (respiratory rate 20 breaths/min, peak inspiratory pressure 12 cm H2O, positive end-expiratory pressure 4 cm H2O, and FIO2 1.0). The lungs were then filled with perfluorocarbon (30 mL/kg) and tidal volume liquid ventilation was instituted, utilizing a newly developed liquid ventilation device. Liquid ventilatory settings were 4 secs for inspiration time, 8 secs for expiration time, 5 breaths/min for respiratory rate, and 15 to 20 mL/kg for tidal volume. Liquid ventilation utilizing this device was also applied to sheep after induction of severe lung injury by right atrial injection of 0.07 mL/kg of oleic acid, followed by saline pulmonary lavage. Extracorporeal life support was instituted to provide a stable model of lung injury. For the first 30 mins of extracorporeal support, all animals were ventilated with gas. Animals were then ventilated with 15 mL/kg of perfluorocarbon over the ensuing 2.5 hrs. MEASUREMENTS AND MAIN RESULTS: In normal cats, mean PaO2 values after 1 hr of liquid or gas ventilation were 275 +/- 90 (SD) torr (36.7 +/- 10.4 kPa) in the liquid-ventilated animals and 332 +/- 78 torr (44.3 +/- 10.4 kPa) in the gas-ventilated animals (NS). Mean PaCO2 values were 40.5 +/- 5.7 torr (5.39 +/- 0.31 kPa) in the liquid-ventilated animals and 37.6 +/- 2.3 torr (5.01 +/- 0.31 kPa) in the gas-ventilated animals (NS). Mean arterial pH values were 7.35 +/- 0.07 in the liquid-ventilated animals and 7.34 +/- 0.04 in the gas-ventilated animals (NS). No significant changes in heart rate, mean arterial pressure, lung compliance, or right atrial venous oxygen saturation were observed during liquid ventilation when compared with gas ventilation. In the lung-injured sheep, an increase in physiologic shunt from 15 +/- 7% to 66 +/- 9% was observed with induction of lung injury during gas ventilation. Liquid ventilation resulted in a significant reduction in physiologic shunt to 31 +/- 10% (p < .001). In addition, the extracorporeal blood flow rate required to maintain the PaO2 in the 50 to 80 torr (6.7 to 10.7 kPa) range was substantially and significantly (p < .001) lower during liquid ventilation than during gas ventilation (liquid ventilation 15 +/- 5 vs. gas ventilation 87 +/- 15 mL/min/kg). CONCLUSIONS: Liquid ventilation can be performed successfully utilizing this simple adaptation of an extracorporeal life-support circuit. This modification to an existing extracorporeal circuit may allow other centers to apply this new investigational method of ventilation in the laboratory or clinical setting.
Animals↗
Liquid ventilation.
Partial liquid ventilation (PLV) developed considerably in the clinical and experimental fields during the past few years. In addition to improved oxygenation and lung mechanics by perfluorocarbon (PFC) administration, recent animal studies have tried to optimize PLV by evaluating the most appropriate ventilatory mode to use during PLV and by adjusting the best level of positive end-expiratory pressure (PEEP). Other pathophysiological aspects of acute lung injury that may be positively affected by liquid ventilation have been studied, including regional blood flow redistribution, reduction in ventilator-induced lung injury, and antiinflammatory properties of PFC. Although the precise dosing of PFC is debated, evidence from several experimental studies supports the use of smaller doses of PFC because larger doses increase the occurrence of baro- and volutrauma. In the clinical field, after promising data from preliminary studies, an international randomized controlled trial is on the verge of completion.
Fluorocarbons↗
High-frequency oscillatory ventilation with partial liquid ventilation in a model of acute respiratory failure.
OBJECTIVE: To determine whether there is an improvement in oxygenation when partial liquid ventilation and high-frequency oscillatory ventilation are combined in the treatment of acute lung injury, compared with high-frequency oscillatory ventilation alone. DESIGN: Controlled animal trial. SETTING: Research laboratory in a university setting. SUBJECTS: Ten 3-kg piglets. INTERVENTIONS: Anesthetized piglets underwent high-frequency oscillatory ventilation, with mean airway pressure of 20 cm H2O, before induction of acute lung injury with repeated saline lavage. When PaO2 values were < 100 torr (< 13.3 kPa), five animals were randomized to receive escalating doses (3, 15, and 30 mL/kg) of perflubron at 60-min intervals. The other five animals remained on high-frequency oscillatory ventilation only. Sham dosing was performed at 60-min intervals in these animals. Arterial blood gases were obtained in both groups at baseline, after injury, and after perflubron and sham doses. MEASUREMENTS AND MAIN RESULTS: Statistically significant improvements in oxygenation were demonstrated in animals that received 3 mL/kg of perflubron with high-frequency oscillatory ventilation compared with animals receiving high-frequency oscillatory ventilation alone (253 +/- 161 vs. 90 +/- 30 torr [33.65 +/- 21.46 vs. 12.0 +/- 4.0 kPa], p < .05). Improvements in oxygenation with additional administration of perflubron were not greater than the improvements seen in the high-frequency oscillatory ventilation-only group. PaCO2 and pH were similar in both groups at all times. No hemodynamic compromise occurred in either group of animals. CONCLUSIONS: The combination of low-dose perflubron with high-frequency oscillatory ventilation leads to more rapid improvement in arterial oxygenation than high-frequency oscillatory ventilation alone, in a piglet model of acute lung injury. Although the group receiving high-frequency oscillatory ventilation alone eventually achieved PaO2 values that were equivalent to the group receiving high-frequency ventilation and perflubron, the combination of perflubron with high-frequency oscillatory ventilation may permit effective oxygenation and ventilation at lower mean airway pressures by facilitating alveolar expansion and decreasing intrapulmonary shunt.
Analysis of Variance↗