Total liquid ventilation reduces oleic acid-induced lung injury in piglets / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pediatric patients are susceptible to lung injury that does not respond to traditional therapies. Total liquid ventilation has been developed as an alternative ventilatory strategy for severe lung injury. The aim of this study is to investigate the effect of total liquid ventilation on oleic acid (OA)-induced lung injury in piglets.</p><p><b>METHODS</b>Twelve Chinese immature piglets were induced acute lung injury by OA. Twelve piglets were randomly treated with conventional gas ventilation (control group) or total liquid ventilation (study group) for 240 minutes. Samples for blood gas analysis were collected before, and at 60-minute intervals after OA-induced lung injury. The degree of lung injury was quantified by histologic examination. The inflammatory cells and the levels of IL-1β, IL-6, IL-10 and TNF-α in plasma, tissue and bronchoalveolar lavage were analyzed.</p><p><b>RESULTS</b>Neutrophil and macrophage counts in bronchoalveolar lavage were significantly decreased in the study group (P < 0.05). The total lung injury score was also reduced in the study group (P < 0.05). The concentrations of IL-1β, IL-6, IL-10 and TNF-α in plasma, tissue and bronchoalveolar lavage were significantly reduced in the study group (P < 0.05).</p><p><b>CONCLUSIONS</b>Total liquid ventilation reduces biochemical and histologic OA-induced lung injury in piglets.</p>

Effect of partial liquid ventilation on lung function in oleic acid-induced lung injury model of piglets / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pediatric patients are susceptible to lung injury that does not respond to traditional therapies. Partial liquid ventilation (PLV) has been developed as an alternative ventilatory strategy for treating severe lung injury. The aim of this study is to investigate the effect of PLV on lung function in immature piglets.</p><p><b>METHODS</b>Acute lung injury was induced in 12 Chinese immature piglets by oleic acid (OA). The animals were randomly assigned to two groups (n = 6 each group): (1) conventional mechanical ventilation (MV) group and (2) PLV with FC-77 (10 ml/kg) group. Mean arterial blood pressure (MAP), mean pulmonary arterial pressure (MPAP), central venous pressure (CVP), left atrial pressure (LAP), systemic vascular resistance (SVR), pulmonary vascular resistance (PVR), cardiac output (CO), mean pressure of airway (Paw), dynamic lung compliance (Cydn), and arterial blood gases were measured during the observation period.</p><p><b>RESULTS</b>No piglet died in either group with severe lung injury. After four hours of ventilation, pH in the MV group gradually decreased to lower than 7.20, while in the PLV group, pH also gradually decreased but remained higher than 7.20 (P < 0.05). Partial pressure of oxygen in artery (PaO2) decreased in both groups, but with a significant difference between the PLV group and MV group (P < 0.05). Partial pressure of carbon dioxide in artery (PaCO2) increased in both groups, but with a significant difference between the PLV group and MV group (P < 0.05). Paw increased in both groups, but was not significantly different (P > 0.05). Cydn decreased in both groups, but without a significant difference (P > 0.05). At four hours, heart rate (HR) and MAP in both groups decreased. MPAP in both groups increased, and there was a significant difference between the two groups (P < 0.05). CVP was stable in both groups. At four hours, PVR and LAP were increased in both groups. CO was decreased in both groups (P < 0.05). SVR was stable during the observation time.</p><p><b>CONCLUSION</b>PLV did not improve outcome in changes of lung function.</p>

Partial liquid ventilation decreases tissue and serum tumor necrosis factor-α concentrations in acute lung injury model of immature piglet induced by oleic acid / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pediatric patients are susceptible to lung injury. Acute lung injury in children often results in high mortality. Partial liquid ventilation (PLV) has been shown to markedly improve oxygenation and reduce histologic evidence of injury in a number of lung injury models. This study was designed to examine the hypothesis that PLV would attenuate the production of local and systemic tumor necrosis factor (TNF)-α in an immature piglet model of acute lung injury induced by oleic acid (OA).</p><p><b>METHODS</b>Twelve Chinese immature piglets were induced acute lung injury by OA. The animals were randomly assigned to two groups of six animals, (1) conventional mechanical ventilation (MV) group and (2) PLV with 10 ml/kg FC-77 group.</p><p><b>RESULTS</b>Compared with MV group, the PLV group had better cardiopulmonary variables (P < 0.05). These variables included heart rate, mean blood pressure, blood pH, partial pressure of arterial oxygen (PaO2), PaO2/inspired O2 fraction (FiO2) and partial pressure of arterial carbon dioxide (PaCO2). PLV reduced TNF-α levels both in plasma and tissue compared with MV group (P < 0.05).</p><p><b>CONCLUSION</b>PLV provides protective effects against TNF-α response in OA-induced acute lung injury in immature piglets.</p>

Manteniendo la permeabilidad de la vía aérea / Keeping patent airways

Ya sea en el ambiente intrahospitalario o fuera de él, el mantener la permeabilidad de la vía aérea tiene un rol importante en el paciente en estado crítico. La evaluación inicial apropiada aplicando el MES (miro, escucho, siento) determinará clínicamente si existe falta de permeabilidad de la vía aérea o necesidad de ventilación asistida. Si no existe permeabilidad de la vía aérea se puede realizar la maniobra de frente-mentón, siempre y cuando no haya sospecha de lesión cervical, en cuyo caso se puede realizar la maniobra de tracción mandibular. Si el paciente requiriera ventilación manual luego de realizar la maniobra de frente-mentón o de la tracción mandibular, se puede utilizar el dispositivo bolsa-válvula-mascara, que es mucho más eficiente si se realiza con dos operadores. La intubación endotraqueal sigue siendo la medida más efectiva para asegurar una vía aérea permeable, pero se requiere experiencia para realizar dicho procedimiento. Una alternativa de fácil manejo es la colocación de una máscara laríngea o del “combitube” que se realizan a “ciegas”, es decir sin observación directa de la glotis.

Even in the hospital environment or outside it, to maintain the patency of the airway has an important role in the critically ill patient. Appropriate initial assessment using the LHF (look, hear, feel) will determine clinically if there is a lack of permeability of the airway or assisted ventilation need. If there is not patency of the airway, do perform the maneuver of the head tilt / chin lift, as long as there is no suspicion of cervical injury, in which case you can make the jaw thrust. If the patient requires manual ventilation after performing the maneuver of chin lift or jaw thrust, the bag-valve-mask device can be used, which is much more efficiently performed with two operators. Endotracheal intubation remains the most effective measure to ensure a patent airway, but it takes experience to perform the procedure. An easy alternative is the placement of a laryngeal mask or “combitube” in a “blind” manner; which is without direct observation of the glottis.

Recent advances in the management of congenital diaphragmatic hernia.

The management of congenital diaphragmatic hernia (CDH) is undergoing continual change and refinement, fuelled by recent advances in this field. Although many studies have documented the benefits of these recent advances but definite recommendations are lacking. Also, injudicious use of some of these strategies may be counterproductive, underscoring the importance of evidence based treatment strategy. This article discusses the utility of the recent advances in the management of CDH.

Effect of partial liquid ventilation on oleic acid-induced inflammatory responses in piglets / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pediatric patients are susceptible to lung injury. Acute lung injury (ALI) in children often results in a high mortality. Partial liquid ventilation (PLV) has been shown to markedly improve oxygenation and reduce histologic evidence of injury in a number of lung injury models. This study aimed to examine the hypothesis that PLV would attenuate the production of local and systemic cytokines in an immature piglet model of ALI induced by oleic acid (OA).</p><p><b>METHODS</b>Twelve Chinese immature piglets were induced to develop ALI by oleic acid. The animals were randomly assigned to two groups (n = 6): (1) conventional mechanical ventilation (MV) group and (2) PLV with FC-77 (10 ml/kg) group.</p><p><b>RESULTS</b>Compared with MV group, PLV group got better cardiopulmonary variables (P < 0.05). These variables included heart rate, mean blood pressure, blood pH, partial pressure of arterial oxygen (PaO2), PaO2/FiO2 and partial pressure of arterial carbon dioxide (PaCO2). Partial liquid ventilation reduced IL-1beta, IL-6, IL-10 and TNF-alpha both in plasma and tissue concentrations compared with MV group (P < 0.05).</p><p><b>CONCLUSIONS</b>Partial liquid ventilation provides protective effects against inflammatory responses in the lungs of oleic acid-induced immature piglets.</p>

The effects of inspiratory to expiratory ratio on ventilation and oxygenation during high frequency partial liquid ventilation in a rabbit model of acute lung injury / 대한마취과학회지

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.

Pathological change of partial liquid ventilation in a rabbit meconium aspiration lung injury model / 中华儿科杂志

<p><b>OBJECTIVE</b>To observe the pathological change of partial liquid ventilation (PLV) through establishing the rabbit model of acute lung injury (ALI) induced by meconium aspiration.</p><p><b>METHODS</b>Adult, healthy male or female New Zealand white rabbits were randomly allocated into six groups as follows: (1) control group, (2) conventional mechanical ventilation (CMV) group, (3) high-frequency oscillatory ventilation (HFOV) group, (4) CMV combined with PLV group, (5) HFOV combined with PLV group and (6) normal group. The animals were anesthetized with 1% pentobarbital and tracheotomy was performed and endotracheal tube was placed, 20% meconium fluid (3 ml/kg) was quickly injected into the lung through the endotracheal tube and arterial blood gas was analyzed 30 minutes later. ALI was indicated when P/F ratio (PaO2)/FiO(2)) was < or = 300 mm Hg (1 mm Hg = 0.133 kPa) and Cdyn Dynamic Compliance declined by more than 30% of the baseline. The animals were then randomly allocated into one of the 6 groups. In PLV groups (including CMV + PLV and HFOV + PLV) warmed (37 degrees C) and oxygenated perfluorocarbon was slowly instilled into the lungs of the rabbits through the endotracheal tube at a low-dose 3 ml/kg, then set 15-min positive pressure by sacculus proprius to guarantee perfluorocarbon to steadily diffuse in to the lungs. Six hours after ventilation the animals were sacrificed by using overdose of room air instillation via vein. The lungs were taken and fixed in 4% paraformaldehyde (PFA) and were stained with hematoxylin-eosin (HE). Pathological evaluations included inflammatory manifestation, edema and hemorrhage in both alveolar and interstitial area, damages of small airway (alveolar tube and alveolar bursa) and hyaline membrane formation. One way analysis of variance, Student Newman-Keuls (SNK) method and Kruskal-Wallis (K-W) test were used for comparisons.</p><p><b>RESULTS</b>With the exception of normal group 30 minutes after meconium injections blood gas analysis in different groups showed significant changes and PaO(2)/FiO(2) (< 300 mm Hg), Cdyn declined by more than 60% compared with baseline (P < 0.05). The pathological analysis showed that alveolar and interstitial inflammation, edema, alveolar and interstitial hemorrhage, and small airway damage existed in each group. The hyaline membrane formation was found in one of CMV + PLV group rabbits. The perfluorocarbon-treated animals (CMV + PLV and HFOV + PLV) showed significantly less injury in dependent lung and less damage of small airway (CMV + PLV or HFOV + PLV vs. CMV = 1.1 +/- 0.4 or 0.9 +/- 0.3 vs 2.6 +/- 0.5) compared with the animals of CMV group (P < 0.01). HFOV group (2.1 +/- 0.3) also had less alveolar and interstitial inflammation compared with CMV group (3.0 +/- 0) (P < 0.05), and there was less evidence of alveolar and interstitial edema in the animals treated with HFOV + PLV (1.0 +/- 0.7) compared with CMV (2.0 +/- 0.8) (P < 0.01). Treatment with perfluorocarbon did not result in significant difference in alveolar and interstitial hemorrhage. Compared with CMV and HFOV groups, the groups treated with PLV showed lower mortality of animals (21.4% and 14.3%).</p><p><b>CONCLUSIONS</b>PLV can alleviate the histological damage of acute lung injury induced by meconium aspiration and increased survival chance and therefore PLV would be a useful treatment for MAS. The effectiveness and safety of application of PLV should be evaluated in clinical studies.</p>

Ventilatory strategies and adjunctive therapy in ARDS.

Acute respiratory distress syndrome, a diagnosis based on physiologic and radiological criteria, occurs commonly in critical care setting. A major challenge in evaluating therapies that may improve survival in ARDS is that it is not a single disease entity but, rather, numerous different diseases that result in endothelial injury, where the most obvious manifestation is within the lung resulting in pulmonary oedema. It has been shown that poor ventilatory technique that is injurious to the lungs can propagate systemic inflammatory response and adversely affect the mortality. The current data suggest that high tidal volumes with high plateau pressures are deleterious and a strategy of ventilation with lower tidal volumes and lower plateau pressure is associated with lower mortality. There may be a role for recruitment manoeuvres as well. Other forms of respiratory support still require further research. The present understanding of optimal ventilatory management and other adjunctive therapies are reviewed.

O papel da ventilação líquida no tratamento da insuficiência respiratória aguda em crianças - uma revisão sistemática / The role of liquid ventilation in the treatment of acute respiratory failure in children - a systematic review

OBJETIVO: A ventilação líquida consiste no preenchimento total ou parcial dos pulmões por líquido (perfluorocarbono), eliminando a interface ar-líquido da membrana alveolar e reduzindo a tensão superficial em pulmões com deficiência de surfactante. Este trabalho tem como objetivo avaliar o papel da ventilação líquida no tratamento da insuficiência respiratória aguda em crianças. MÉTODOS: A técnica empregada foi uma revisão sistemática da literatura sobre ventilação líquida. O levantamento bibliográfico utilizou os bancos de dados MEDLINE, LILACS, COCHRANE LIBRARY e referências de artigos. Os termos utilizados para pesquisa foram: liquid ventilation, respiratory distress syndrome, meconium aspiration syndrome, congenital diaphragmatic hernia e acute respiratory distress syndrome. Foram procurados ensaios clínicos randômicos, estudos de coorte, caso-controle e série de casos. Os desfechos avaliados foram resposta sobre a oxigenação sangüínea, mecânica respiratória e a sobrevida dos pacientes. RESULTADOS: Foram selecionadas 284 publicações relacionadas à ventilação líquida durante o período de estudo. Destas, 22 (7,7 por cento) eram ensaios clínicos, e apenas seis referiam-se à utilização da ventilação líquida em crianças. Todas as seis publicações foram caracterizadas como série de casos e analisadas separadamente. CONCLUSÃO: A partir da análise dos estudos clínicos, pôde-se concluir que, pela falta de estudos clínicos randômicos e controlados, a ventilação líquida não pode ser recomendada como terapia para insuficiência respiratória aguda em pediatria.

Liquid ventilation.

Respiratory diseases are the commonest cause of morbidity and mortality in newborn babies. During the past few years several new modalities of treatment like surfactant have been introduced. One of them, and probably the most fascinating, is of liquid ventilation. Partial liquid ventilation, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using a conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. It shows further promise for lung lavaging procedures, pulmonary image enhancement, pulmonary administration of drugs and as a technique to increase functional residual capacity in lung hypoplasia syndromes. There are no long-term side effect reported.

O impacto de estratégias de ventilação mecânica que minimizam o atelectrauma em um modelo experimental de lesão pulmonar aguda / The impact of mechanical ventilation strategies that minimize atelectrauma in an experimental model of acute lung injury

OBJETIVO: Avaliar se estratégias ventilatórias que buscam a estabilização alveolar e a prevenção do atelectrauma estão associadas a desfechos fisiológicos mais favoráveis em um modelo experimental de lesão pulmonar aguda combinada. MÉTODOS: Trinta e nove coelhos foram instrumentados e ventilados com uma fração inspirada de oxigênio (FiO2) de 1,0. A lesão pulmonar foi induzida pela infusão venosa de lipopolissacarídeo de E. coli e por repetidas lavagens traqueais com solução salina. Os animais foram randomizados a receber ventilação mecânica convencional com volume corrente de 10 ml/kg, pressão expiratória final (PEEP) de 4 cm H2O; ventilação mecânica convencional com surfactante (Infasurf, 3 mg/kg, ET); ventilação líquida parcial (18 ml/kg de perflubron, ET); ou ventilação oscilatória de alta freqüência, com pressão média de via aérea de 14 cm H2O e freqüência de 10 Hz. Animais sadios submetidos a instrumentação e ventilação convencional serviram como controles. Os grupos ventilação mecânica convencional com surfactante, ventilação líquida parcial e controle foram ventilados com parâmetros idênticos ao grupo ventilação mecânica convencional. Os animais foram estudados por 4 horas, durante as quais gasometrias arteriais foram obtidas a cada 30 minutos. Após o sacrifício, os pulmões foram retirados para graduação de lesão através de um escore de dano histológico e dosagem de 4-hidroxi-nonenal, um marcador de peroxidação lipídica. RESULTADOS: A ventilação mecânica convencional resultou em hipoxemia e lesão pulmonar significativa. Animais tratados com ventilação líquida parcial, ventilação oscilatória de alta freqüência ou ventilação mecânica convencional com surfactante apresentaram oxigenação adequada, mas a ventilação mecânica convencional com surfactante resultou em escores de lesão pulmonar mais elevados e maior dano oxidativo. CONCLUSÕES: Estratégias que minimizam o atelectrauma (ventilação mecânica convencional e ventilação oscilatória de alta freqüência) estão associadas a oxigenação adequada e atenuação da lesão pulmonar. A reposição de surfactante melhora a oxigenação em comparação com a ventilação mecânica convencional, mas resulta em lesão pulmonar aumentada, presumivelmente porque o PEEP inadequadamente baixo foi insuficiente para estabilizar os alvéolos durante a expiração.

Prone Positioning Improves Oxygenation Without Adverse Hemodynamic Effects during Partial Liquid Ventilation in a Canine Model of Acute Lung Injury

BACKGROUND: Partial liquid ventilation (PLV) and prone positioning can improve the arterial oxygenation (PaO2) in acute lung injury (ALI). We evaluated the effect of prolonged prone positioning during partial liquid ventilation (PLV) in a canine model of acute lung injury. METHODS: Six mongrel dogs (weighing 17.4 +/- 0.7 kg each) were anesthetized, intubated and mechanically ventilated. After 1 hour of baseline stabilization, the dogs' lungs were instilled with 40 mL/kg perfluorocarbon (PFC). PLV was first performed in the supine position for 1 hour (S1), then in the prone position for 3 hours with hourly measurements (P1, P2, P3), and finally, PLV was performed with the animal turned back to the supine position for 1 hour (S2). RESULTS: After instillation of the PFC, the PaO2 significantly increased from 99.2 +/- 32.6 mmHg at baseline to 198.1 +/- 59.2 mmHg at S1 (p=0.001). When the dogs were turned to the prone position, the PaO2 further increased to 288.3 +/- 80.9 mmHg at P1 (p=0.008 vs. S1) : this increase was maintained for 3 hours, but the PaO2 decreased to 129.4 +/- 62.5 mmHg at S2 (p< 0.001 vs. P3). Similar changes were seen in the shunt fraction. There were no significant differences for the systemic hemodynamic parameters between the prone and supine positions. CONCLUSION: Prolonged prone positioning during PLV in an animal model of ALI appears to improve oxygenation without any hemodynamic compromise.

The Effect of High Frequency Jet Ventilation with Partial Liquid Ventilation in Saline Lavaged Lung Injury in the Rabbit / 대한마취과학회지

BACKGROUND: Morbidity and mortality rates from acute respiratory failure remain noteworthy despite advances in conventional ventilatory techniques and improvements in supportive care. Repeated, the large tidal volume breaths during positive pressure mechanical ventilation lead to destruction of alveoli and pulmonary capillaries. Moreover, the overdistention of terminal lung units is considered as an important mechanism of ventilator induced lung injury. High frequency ventilation (HFV) is a technique involving a small tidal volume, and a higher than physiologic respiratory rate. Partial liquid ventilation (PLV), also known as perfluorocarbon-associated gas exchange, is a new technique for respiratory support. This study was designed to compare conventional mechanical ventilation (CMV) and high frequency jet ventilation (HFJV), in combination with PLV. METHODS: Twenty rabbits were anesthetized with xylazine, ketamine and vecuronium. We studied rabbits with lung injury induced by saline lavage. Animal were randomized into one of two treatment groups. Ventilator parameters included the following; CMV: FIO2 of 1.0, respiratory rate 20-30 breaths/min, I/E ratio 1 : 1; HFJV: respiratory rate 2 Hz, driving pressure 2psi. Animals were briefly disconnected from the ventilator and lungs were lavaged with warmed saline. This procedure was repeated until PaO2 < 100 mmHg. After one hour, we initiated the instillation of perfluorodecalin via an endotracheal tube. Baseline measurements were performed at 60 mins after the induction of anesthesia and repeated again at hour after the induction of lung injury, which included 30 mins of stabilization. After PFD instillation, data were recorded. RESULTS: All animals developed hypoxemia after the lung injury, but oxygenation improved significantly after perfluorodecalin instillation. The PLV-HFJV group showed a high pH and a low PaCO2. Mean arterial pressure, cardiac index and systemic vascular resistance was differed significantly. Although there were no qualitative histological differences between lungs ventilated with HFJV on CMV, the lower lobes of all PLV-treated animals were damaged less than the upper lobes, but without statical significance. CONCLUSIONS: PLV-HFJV produced a more efficient gas exchange than PLV-CMV. No significant difference was observed in the pulmonary pathologies of the groups.

Effects of Perfluorocarbon Associated High Frequency Oscillatory Ventilation on Hemodynamics and Gas Exchange in the Newborn Piglets with Respiratory Distress

We sought to know whether there is a further improvement in gas exchange when partial liquid ventilation (PLV) is added to high-frequency oscillatory ventilation (HFOV) in a piglet model of saline lavage-induced acute lung injury. Seven 7-9 day-old newborn piglets of mixed strain were treated with repeated saline lavage to achieve a uniform degree of acute lung injury. Then, HFOV were applied to the subject. Four animals received two consecutive doses (15 mL/kg) of perfluorodecalin at 30-min interval (PFC+HFOV group). The other three animals remained on HFOV alone (HFOV-only group). Repetitive lung lavage led to a significant acute aggravation in both gas exchange and hemodynamic parameters. Subsequent application of HFOV produced a significant rapid recovery in both gas exchange and hemodynamic parameters to near baseline levels. During and after perfluorodecalin dosing, there were no significant changes in gas exchange or hemodynamic parameters over time in both groups, and no significant differences in gas exchange or hemodynamic parameters between groups. We concluded that the addition of 30 mL/kg of perfluorodecalin to HFOV showed no detrimental effect on hemodynamics, but did not produce a significant improvement in gas exchange over a three-hour period.

The Effects of Perfluorocarbon on Respiratory Mechanics and Pulmonary Gas Exchange with Methacholine-induced Bronchoconstriction in Cats / 대한마취과학회지

BACKGROUND: Perfluorocarbon (PFC) liquids have high oxygen carrying capacity and relatively low surface tension allowing them to spread evenly through the diseased lung, especially in the case of adult respiratory distress syndrome. But few studies have demonstrated the effects of PFC on a bronchoconstriction model. The aim of this study was to investigate the effects of PFC on pulmonary mechanics and gas exchange in methacholine-induced bronchoconstricted cats using a flow interruption technique. METHODS: Twenty male cats were divided into four groups; control group (group C, n = 5), PFC group (group P, PFC 5 ml/kg, n = 5), methacholine group (group M, 25 microgram/kg/min, n = 5), PFC and methacholine group (group MP, n = 5). Respiratory pressure using a flow interruption technique was measured immediately after stabilizing the heart rate and blood pressure 0, and 15, 30 and 60 min after the start of the intratracheal administration of PFC and/or methacholine infusion, depending on the group. Arterial blood gas analysis was done to compare arterial partial oxygen pressure among the groups at the time of measuring the pressure values. The pressure data was transferred to a personal computer and analyzed using ANADAT software program. Respiratory, airway and tissue viscoelastic pressure were calculated. Statistical analysis was done by ANOVA and statistical significance was defined as P <0.05. RESULTS: Group M and MP showed significantly increased airway pressures compared with group C (P <0.05), but there was no difference among the groups in terms of viscoelastic pressure. Arterial blood gas analysis showed that group P and MP had lower arterial partial oxygen pressures than group C (P <0.05). CONCLUSIONS: This study demonstrates that the intratracheal administration of PFC in a bronchoconstriction cat model increases airway pressure more than tissue viscoelastic pressure, and decreased arterial oxygen partial pressure. We conclude that the intratrachel administration of PFC is not to be recommended in bronchoconstrictive situations.

Combined Effect of Low-dose Nitric Oxide Gas Inhalation with Partial Liquid Ventilation on Hemodynamics, Pulmonary Function, and Gas Exchange in Acute Lung Injury of Newborn Piglets

We conducted a randomized animal study to determine whether there is a cumulative effect on hemodynamics, pulmonary function, and gas exchange when low dose nitric oxide (NO) is added to partial liquid ventilation (PLV) in acute lung injury. ighteen newborn piglets were saline-lavaged repeatedly, and randomly divided into two groups: PLV with perfluorocarbon group (n=8) and lavage only (control) group (n=10). Perfluorodecalin (30 mL/kg) was instilled into the endotracheal tube for 30 min, followed by 5-10 mL/kg/hr. Fifteen minutes after the completion of perfluorodecalin dosing, NO (10 ppm) was added to the inspiratory gas in an "on/off" manner. Perfluorodecalin instillation produced a significant improvement in gas exchange, pulmonary mechanics, shunt, and pulmonary arterial pressure (PAP). The addition of NO produced a further significant improvement in PaO2 and PAP. The "on/off" response to NO was seen apparently in PAP, PaO2, dynamic compliance, and shunt. All the variables in control group were remained at near the after-lavage levels without significant improvements until the end of the experiment. We concluded that NO might have a cumulative effect on gas exchange when combined with PLV, and this might be attributable to deceased PAP and V/Q mismatching.

Ventilação líquida: revisão da literatura / Liquid ventilation: literature review

Atualmente, novas alternativas de ventilação têm sido estudadas em quadros de insuficiência respiratória, com o objetivo de melhorar a oxigenação e minimizar a agressão ao parênquima pulmonar. A utilização de perfluorocarbonos líquidos administrados diretamente na via aérea vem sendo ostensivamente estudada em modelos de lesão pulmonar e em alguns ensaios clínicos, demonstrando bons resultados com relação à troca gasosa, mecânica ventilatória e propriedades antiinflamatórias. Os PFCs são substâncias que possuem baixa tensão superficial, alta densidade, são insolúveis em água, além de permitirem alta difusão de oxigênio e gás carbônico. Esses compostos atuam recrutando alvéolos colapsados, melhorando a oxigenação, protegendo a arquitetura pulmonar e atuando como carreadores de impurezas, limpando a superfície alveolar de resíduos da degradação celular. Neste artigo de revisão são apresentadas as diferentes modalidades ventilatórias com perfluorocarbonos e fornecidas informações sobre a utilização e o estado atual da ventilação líquida

The influence of high frequency partial liquid ventilation on the cardiopulmonary function in dogs with inhalation injury / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of high frequency partial liquid ventilation (HFJV) on the cardiopulmonary function in dogs with inhalation injury.</p><p><b>METHODS</b>Sixteen 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSION</b>Compared 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.</p>