Utilization of a model lung system to assess the effects of an inspiratoryimpedance threshold valve on the relationship between active decompressionand intra-thoracic pressure

Use of an inspiratory impedance valve has recently been shown to increase t he efficacy of standard and active compression-decompression cardiopulmonar y resuscitation. We evaluated the effects of a prototypic impedance valve o n the relationship between the active decompression and intra-thoracic pres sure using a mechanical model lung system. intermittent impedance to inspir atory flow of respiratory gases during the decompression phase of active co mpression-decompression cardiopulmonary resuscitation significantly decreas ed the intra-thoracic pressure, while the pressure was almost zero cm H2O d uring the cardiopulmonary resuscitation cycle when the impedance threshold valve was not functioning. Thus, this mechanical model will help in evaluat ing the valve as well as in optimizing its function by simulating various f orms of lung disease. (C) 1999 Elsevier Science Ireland Ltd. All rights res erved.