The Science Journal of the American Association for Respiratory Care

2001 OPEN FORUM Abstracts

Venturi MaskSystem to Support Space Medical Operations

 TerrellM. Guess, George Beck BA, RRT WyleLaboratories Life Sciences Systems & Services, Houston, TX

Background: Whenthe space shuttle is not docked, use of the Soyuz transport/escape vehicle formedical deorbit to earth from the International Space Station (ISS) requiresa change in philosophy for medical emergencies from one of stabilize and transport,to stabilize and manage. The Soyuz is not capable of transporting an intubated/ventilatedcrew member therefore, on-orbit weaning and extubation along with a mechanismfor delivering variable FIO2 is required. Shuttle (STS) and InternationalSpace Station (ISS) medical kits do not contain a method for delivering adjustableconcentrations of O2 during medical contingencies. A standard air/O2blender is not feasible as the ISS has only compressed O2 and N2.In addition, there is no method or supporting equipment (weaning modes of ventilation,spirometer, etc) for weaning from mechanical ventilation. This study soughtto identify a Venturi mask system that could be used on STS and ISS for supplementalO2 and weaning via a T-Piece.

Method: Atrade study of Venturi mask vendors was done, 8 vendors were identified, 5 ofwhich, responded and supplied samples. All units were tested for delivered FIO2using a standard back-pressure compensated flowmeter (Ohmeda Model AHE, Columbia,MD) and the ISS flowmeter with a calibrated O2 analyzer (ServomexModel 571, Sussex, England). Units were evaluated for ease of use, number ofparts, range of concentrations and visibility of the markings.

Results: Allof the units delivered O2 accurately at the set concentration (maxFIO2 difference ±0.02) using the standard and ISS flowmeters andall supported use with a T-piece. The Salter model 8150 was found to have thefewest parts and was one of the easiest to read and therefore would supportuse by a non-physician crew medical officer in flight.

Conclusion: AVenturi system could be used to support low-dose O2 administrationand used with a T-piece for spontaneous breathing trials. Its use would enhancecurrent care capability, avoid inefficient O2 use and minimize therisk of O2 toxicity and fire. Stonehill and Peoples (1982) demonstratedthat Venturi devices maintain the set inspired O2 fraction over arange from sea level to 10,000 feet altitude the minimum nominal cabin pressurefor STS and ISS. While FIO2 will need to be adjusted to maintainan acceptable PIO2 at altitude, their work demonstrates predictableperformance of Venturi devices at altitude. This work was supported under contractto NASA, NAS9-97005.

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Background: Whenthe space shuttle is not docked, use of the Soyuz transport/escape vehicle formedical deorbit to earth from the International Space Station (ISS) requiresa change in philosophy for medical emergencies from one of stabilize and transport,to stabilize and manage. The Soyuz is not capable of transporting an intubated/ventilatedcrew member therefore, on-orbit weaning and extubation along with a mechanismfor delivering variable FIO2 is required. Shuttle (STS) and InternationalSpace Station (ISS) medical kits do not contain a method for delivering adjustableconcentrations of O2 during medical contingencies. A standard air/O2blender is not feasible as the ISS has only compressed O2 and N2.In addition, there is no method or supporting equipment (weaning modes of ventilation,spirometer, etc) for weaning from mechanical ventilation. This study soughtto identify a Venturi mask system that could be used on STS and ISS for supplementalO2 and weaning via a T-Piece.

Method: Atrade study of Venturi mask vendors was done, 8 vendors were identified, 5 ofwhich, responded and supplied samples. All units were tested for delivered FIO2using a standard back-pressure compensated flowmeter (Ohmeda Model AHE, Columbia,MD) and the ISS flowmeter with a calibrated O2 analyzer (ServomexModel 571, Sussex, England). Units were evaluated for ease of use, number ofparts, range of concentrations and visibility of the markings.

Results: Allof the units delivered O2 accurately at the set concentration (maxFIO2 difference ±0.02) using the standard and ISS flowmeters andall supported use with a T-piece. The Salter model 8150 was found to have thefewest parts and was one of the easiest to read and therefore would supportuse by a non-physician crew medical officer in flight.

Conclusion: AVenturi system could be used to support low-dose O2 administrationand used with a T-piece for spontaneous breathing trials. Its use would enhancecurrent care capability, avoid inefficient O2 use and minimize therisk of O2 toxicity and fire. Stonehill and Peoples (1982) demonstratedthat Venturi devices maintain the set inspired O2 fraction over arange from sea level to 10,000 feet altitude the minimum nominal cabin pressurefor STS and ISS. While FIO2 will need to be adjusted to maintainan acceptable PIO2 at altitude, their work demonstrates predictableperformance of Venturi devices at altitude. This work was supported under contractto NASA, NAS9-97005