Failure of exhalation during ventilation with the Dräger Oxylog 2000 ventilator

We describe three cases in which there was failure of exhalation during mechanical ventilation with the Dräger Oxylog 2000 ventilator. Two potential mechanisms for this failure were identified, and were then experimentally reproduced on a test lung. First, a manufacturing fault in the silicone diaphragm in the ventilation valve was discovered. When a small hole in the diaphragm was incompletely perforated, a possible flap valve was formed, limiting exhalation. Second, failure of the one-way rubber disc valve to seat properly in its housing also prevented exhalation. These two previously unreported modes of ventilator failure have been identified. Careful checking of the ventilator circuit before each use is required.