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Device for indicating the presence of carbon dioxide in a patient's exhaled air

  • US 5,468,451 A
  • Filed: 02/10/1994
  • Issued: 11/21/1995
  • Est. Priority Date: 06/29/1992
  • Status: Expired due to Term
First Claim
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1. A device for indicating presence of CO2 in a patient'"'"'s exhaled breath, comprising:

  • a CO2 detector including an indicator element which undergoes a reversible color change in response to exposure thereof to air containing CO2 in concentrations of a same order of magnitude as a CO2 concentration of the patient'"'"'s exhaled breath;

    a heat-moisture exchanger further comprising a housing which includes a first connecting port adapted to be connected to the trachea of a patient and a second connecting port adapted to be connected selectively to a ventilator and an anaesthesia machine and which has mounted in a flow-through passage extending between the connecting ports an exchanger element for the regenerative exchange of heat and moisture between firstly, air which flows through the flow through passage in one direction and, secondly, air which flows through the flow-through passage in an opposite direction;

    the indicator element being disposed in the flow-through passage away from and on the downstream side of the heat-moisture exchanger element in direction of flow of the patient'"'"'s breath and remote from the first connection port, said indicator element being viewable from outside the housing;

    the indicator element having a response time for colour changes responsive to CO2 which is sufficiently short to enable the indicator element to change color upon each breath.

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