1998 OPEN FORUM Abstracts
Mark J. Heulitt, MD
The use of positive pressure ventilation as an effective treatment of acute respiratory failure was first demonstrated 40 years ago during the poliomyelitis epidemic in Europe and Scandinavia. During this epidemic, patients received artificial airways and were manually ventilated for prolonged periods with gases delivered by a simple anesthetic circuit. This in turn ushered in an era of intensive care medicine and the development of the first positive pressure mechanical ventilators (PPV) by Engstrom in Scandinavia and Emerson in North America. Clinical demand for ventilatory support led to the development of these positive pressure ventilators, but not immediately to the discovery of the iatrogenic lung injury associated with it.
Since the introduction of the first ventilators, we have seen major technological advances in ventilator design. However, until recently, there has been no improvement in the survival of patients with respiratory failure for which they were designed to support. Application errors in the use of ventilators may be attributed to the mistaken concept that PPV should mimic normal physiology. Because of this, ventilator settings were chosen to achieve normocarbia with tidal volumes and respiratory rates appropriate for the normal lung.
In the past five years, there has been a rethinking of this approach in pediatric patients due to a growing body of evidence in the scientific literature suggesting that there may be a clinically significant lung injury secondary to mechanical ventilation. This lung injury appears to be directly related to inadequate levels of positive end-expiratory pressure (PEEP) and supraphysiologic tidal volumes. Thus, clinical practice has been modified to open the lung without causing overdistention.
In this lecture, I present the scientific literature as it relates to acute respiratory distress syndrome (ARDS) and ventilatory support. Even though the focus of this article is pediatric ARDS, available data is still limited so data from adult animal studies and clinical trials will be utilized. This discussion will also include non-conventional and adjunct therapies utilized for these patients such as High Frequency Ventilation, ECMO and PLV.
The 44th International Respiratory Congress Abstracts-On-Disk®, November 7 - 10, 1998, Atlanta, Georgia.