Infant ventilators should be tested under physiological load conditions before being used for infant care and periodically during use to verify that they are functioning as expected and according to criteria established by various standards agencies. There is no tester currently available that allows thorough testing of most types of infant ventilators in accordance with these criteria. The objective of this project is to develop such a tester, using as a technological basis the company's adult ventilator tester, already in production. The principal tasks to be accomplished are: developing an infant lung simulator similar to the existing adult lung simulator; interfacing the infant lung to the tester's electronics unit; re-programming the electronics unit; changing electronic and mechanical components as required; testing the unit in a hospital environment. The resulting infant ventilator tester will allow testing under dynamic conditions using an infant lung simulator with variable compliance and airway resistance. The user will be able to initiate automated tests and monitor volumes, pressures, and flows by touching pressure-sensitive pads in response to prompts on an LCD display that also provides waveform graphing and data display. A printer, analog output to a chart recorder, and RS232 interface will also be provided.