High-frequency oscillatory ventilation is not superior to conventional mechanical ventilation in surfactant-treated rabbits with lung injury

Abstract

High-frequency oscillatory ventilation is not superior to conventional mechanical ventilation in surfactant-treated rabbits with lung injury. D. Gommer, A. Hartog, R. Schnabel, A. De Jaegere, B. Lachmann. #ERS Journals Ltd 1999. ABSTRACT: The aim of this study was to compare high-frequency oscillatory ventilation (HFOV) with conventional mechanical ventilation (CMV) with and without surfactant in the treatment of surfactant-deficient rabbits. A previously described saline lung lavage model of lung injury in adult rabbits was used. The efficacy of each therapy was assessed by evaluating gas exchange, lung deflation stability and lung histopathology.Arterial oxygenation did not improve in the CMV group without surfactant but increased rapidly to prelavage values in the other three study groups. During deflation stability, arterial oxygenation decreased to postlavage values in the group that received HFOV alone, but not in both surfactant-treated groups (HFOV and CMV). The HFOV group without surfactant showed more cellular infiltration and epithelial damage compared with both surfactant-treated groups. There was no difference in gas exchange, lung deflation stability and lung injury between HFOV and CMV after surfactant therapy.It is concluded that the use of surfactant therapy in combination with highfrequency oscillatory ventilation is not superior to conventional mechanical ventilation in improving gas exchange, lung deflation stability and in the prevention of lung injury, if lungs are kept expanded. In the first reported high-frequency oscillatory ventilation (HFOV) trial, a low distending airway pressure was used in order to minimize the risk of barotrauma [1]. However, experimental studies have shown that alveoli should be actively opened and that a relatively high airway pressure has to be used to stay above the closing pressure to avoid hypoxaemia and lung injury [2,3]. Results of recent pilot studies in neonates with respiratory distress syndrome (RDS) applying this high-lung volume strategy are encouraging [4±6].To date, very few studies have been published on the combined use of surfactant and HFOVin animals or humans [4, 6±9]. Those studies demonstrated that after surfactant therapy HFOV was superior to conventional mechanical ventilation (CMV) in improving pulmonary function and reducing lung injury [4, 6±9]. However, in those studies, HFOV was used in combination with the high-lung volume strategy whereas CMV was not. Recently, FROESE et al.[8] compared HFOV to CMV after surfactant therapy at low-and high-lung volume and confirmed that HFOV at high-lung volume was superior to the alternatives in improving gas exchange and lung mechanics in lunglavaged rabbits. Surprisingly, these authors were not able to maintain oxygenation above 46.7 kPa (350 mmHg), despite the high-lung volume strategy, after surfactant therapy with the use of CMV [8]. This finding is in contrast to earlier results of CMV with surfactant therapy in lung-lavaged rabbits in which oxygenation increased rapidly to prelavage values aft...

Mechanical Ventilation and Bronchopulmonary Dysplasia

“…HFOV used without the open lung strategy was relatively ineffective in reducing lung injury 73 and several animal studies have indicated that conventional ventilation, when used with the OLC, can achieve similar degrees of lung protection as HFOV, suggesting that optimizing lung volume, rather than frequency, is the key factor. [74][75][76] Clinical application of the OLC with conventional ventilation, however, may not be an easy task and has not been extensively evaluated in clinical trials. 77 Fig.…”

State of the art in conventional mechanical ventilation

“…By contrast, the importance of optimizing lung inflation has long been recognized by users of high-frequency ventilation, where the optimal lung volume strategy has become standard practice and is widely understood to be the key to its success. However, although there are a number of animal studies indicating that conventional ventilation with the OLC can achieve similar degrees of lung protection as high-frequency oscillatory ventilation (HFOV), suggesting that optimizing lung volume rather than frequency is the key factor, [32][33][34][35][36] the clinical application of the OLC with conventional ventilation has not been extensively evaluated in clinical trials. 37 Finally, it is important to understand that there is no single 'safe' PEEP level.…”

Interaction between Surfactant and Ventilatory Support in Newborns with Primary Surfactant Deficiency

“…Recent animal studies have come to different conclusions as to whether the combination of optimal lung volume strategy achieved by HFOV with surfactant is superior to the lungprotective strategy of CMV with higher PEEP and smaller tidal volumes, in terms of more uniform lung inflation, attenuation of the loss of pulmonary compliance, less pulmonary inflammation, and reduction of the conversion of large surfactant aggregates into smaller aggregate forms. Some of these studies favored HFOV [32][33][34], others showed equal effectiveness of CMV and HFOV as long as the open lung concept was satisfied [35][36][37][38].…”