Method for determining whether respiratory gas is present in a gaseous sample
DCFirst Claim
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1. A method for determining whether a gaseous sample contains a predetermined concentration of carbon dioxide, comprising the step of:
- contacting the gaseous sample with a dry reagent detector comprising a carrier having an aqueous indicating composition applied thereto for providing an indication of the presence of the predetermined concentration of carbon dioxide in the sample within a diagnostically effective period of time when the carbon dioxide concentration in the sample is at least about 2% and providing said indication after about ten minutes when the carbon dioxide concentration in the sample is about 0.03%.
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Abstract
A method is disclosed for determining whether respiratory gas is present in a gaseous sample by which the sample is brought into contact with an indicator which yields an indication within a diagnostically effective period of time of the presence in the sample of carbon dioxide in concentration of at least 2% while an indication of the presence of carbon dioxide in a sample of ambient air would be delayed beyond a predetermined period of time. The method has particular utility in determining the correct placement of an endotracheal catheter in a patient or in the detection of apnea.
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Citations
25 Claims
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1. A method for determining whether a gaseous sample contains a predetermined concentration of carbon dioxide, comprising the step of:
contacting the gaseous sample with a dry reagent detector comprising a carrier having an aqueous indicating composition applied thereto for providing an indication of the presence of the predetermined concentration of carbon dioxide in the sample within a diagnostically effective period of time when the carbon dioxide concentration in the sample is at least about 2% and providing said indication after about ten minutes when the carbon dioxide concentration in the sample is about 0.03%. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- 18. A method for determining whether a gaseous sample contains a predetermined concentration of carbon dioxide, comprising contacting the gaseous sample with a detector comprising a carrier to which a dried non-volatile indicating element has been applied, said indicating element providing a first response within a diagnostically effective period of time when the carbon dioxide concentration in the sample is at least about 2% but not providing said first response for more than about ten minutes when the carbon dioxide concentration in the sample is on the order of 0.03%, and providing a second response within said diagnostically effective period of time when the ample is replaced with ambient air.
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21. A method of making a respiratory gas detector comprising the steps of:
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selecting an aqueous alkaline solution; combining the aqueous alkaline solution with a chromogenic pH-sensitive indicator to form a composition; correlating the nature and concentration of the composition to the nature and concentration of the pH-sensitive indicator so that the composition produces a predetermined response within a first predetermined period of time to the exposure thereof to carbon dioxide at a concentration of at least about 2% and produces a response for a second predetermined period of time longer than said first predetermined period of time when the composition is exposed only to concentrations of carbon dioxide of no more than about 0.03%; depositing the composition on a carrier and drying said carrier to form a dry reagent respiratory gas detector. - View Dependent Claims (22, 23, 24, 25)
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Specification