The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

THERMODYNAMIC PROPERTIES OF STORED HELIUM-OXYGEN, OXYGEN AND HELIUM CYLINDERS IN EXTREME ENVIRONMENTALTEMPERATURES.



Steve T Polston, RRT, Norton Healthcare inc. Louisville, KY, Michelle Martin, University of Louisville School of Medicine, Kendra Sikes, EIT, Norton Healthcare inc. Louisville, KY, In K. Kim, MD, Assistant Professor, Pediatric Emergency Medicine, University of Louisville Health Sciences Center.

BACKGROUND:
Storing helium: oxygen (heliox) or oxygen H-cylinders outside due to storage restrictions exposes the gases to a wide range of ambient seasonal temperatures. Cold or hot gases administered to patients may exacerbate underlying respiratory diseases such as asthma and chronic lung diseases. For example, cold gas exposure may cause bronchoconstriction, rhinorrhea, or laryngospasm. Warm gas exposure may cause thermal injury. These clinical effects may be more significant with heliox because it has approximately 5.7 times higher thermal conductivity, 0.15 watt/meter/Kelvin (W/mK) relative to nitrogen (0.026 W/mK), oxygen (0.026 W/mK) , and room air (0.026 W/mK). If H-cylinders are stored outside, a protocol allowing for the gases to attain room temperature before administration to patients could prevent possible adverse clinical manifestations. This study investigates the amount of time needed to sufficiently allow cooled (-26ºC) and warmed gases (51ºC) in H-cylinders to equilibrate with room temperature.

METHOD:
Four steel H-cylinders of different gas mixtures: 70% Helium: 30% Oxygen (70:30 Heliox), 80% Helium: 20% Oxygen (80:20 Heliox), 100% Oxygen, and 100% Helium were placed overnight into a -26ºCelsius (C) freezer until the gases reached -26ºC. Then, they were placed into room temperature (on average 23ºC). The gas temperatures were measured approximately every 15 minutes until they were at room temperature. In a second experiment, the H-cylinders were placed in a 51ºC heat chamber until the gases reached 51ºC. They were then placed into room temperature. The gas temperatures were measured approximately every 15 minutes until they were at room temperature.

RESULTS:
One hundred percent oxygen, 100% helium, 70:30 Heliox and 80:20 Heliox mixtures warmed to room temperature by 180 minutes after being removed from the -26º C freezer. In contrast, 100% oxygen, 100% helium, 70:30 Heliox and 80:20 Heliox mixtures cooled from 51ºC to room temperature by 125 minutes.

CONCLUSION:
Immediately utilizing heliox or oxygen gases stored in external environments may introduce adverse temperatures to a patient's respiratory system. Heliox or oxygen H-cylinders at -26ºC should be placed in room temperature for approximately 180 minutes to assure equilibration to room temperature before administration to patients. Heliox or oxygen H-cylinders at 51ºC should be placed in room temperature for approximately 125 minutes to assure equilibration to room temperature before administration to patients.

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