Spirometer

Claim 2

A spirometer comprising a disposable flow tube having an opening through it for transmitting human breath, a transverse lateral channel opening into the flow tube, a lateral conduit having an opening through it communicating with the channel, means in the flow tube for aspirating gas flow from the atmosphere through the lateral conduit and channel, and into the flow tube in response to the transmission of breath through the flow tube, means for detecting the aspirated gas flow in the conduit when breath is transmitted through the flow tube, and means connected to the gas flow detecting means for measuring the flow of breath.

Claim 3

Apparatus according to claim 1 wherein the lateral conduit is releasably sealed to the flow tube.

Claim 4

Apparatus according to claim 1 wherein the means for aspirating gas flow comprises a constriction disposed within the flow tube to create a partial vacuum for withdrawing gas from the lateral conduit into the flow tube.

Claim 5

Apparatus according to claim 1 wherein the gas flow detecting means comprises temperature-sensitive transducer means having an output responsive to gas flow, and wherein the measuring means inclUdes means responsive to the transducer means output for producing an electrical output signal equivalent to the rate of gas flow through the lateral conduit.

Claim 6

Apparatus according to claim 4 wherein the measuring means includes means for recording the electrical output signal.

Claim 7

Apparatus according to claim 4 wherein the transducer comprises a circuit element adapted to develop variations in electrical conductivity in response to temperature changes induced by gas flow in the conduit.

Claim 8

Apparatus according to claim 4 wherein the means responsive to the transducer output comprises bridge means adapted to compensate for the variations in electrical conductivity developed by the transducer.

Claim 9

Apparatus according to claim 7 wherein the bridge means includes compensating means adapted to correct for changes in ambient temperature.

Claim 10

Apparatus according to claim 1 including a second transverse lateral channel opening into the flow tube for transmitting a steady flow of gas to the interior of the flow tube to bias the flow of breath through the flow tube.

Claim 11

Apparatus according to claim 1 in which the gas flow detecting means includes a body having an elongated narrow passage extending through it and opening to the atmosphere, the narrow passage being adapted for communication with the lateral conduit of the flow tube; and an elongated temperature-sensitive wire in the passage for detecting gas flow through the passage.

Claim 12

Apparatus according to claim 10 in which the narrow passage extends through the body and is open to the atmosphere at both ends, and in which the body includes a lateral channel transverse to the narrow passage and having one end opening into an intermediate portion of the narrow passage, the other end of the lateral channel opening into the lateral conduit.

Claim 13

Apparatus according to claim 10 in which the diameter of the narrow passage is about 0.04 inch, and the diameter of the temperature-sensitive wire is about 0.0005 inch.

Claim 14

Apparatus according to claim 10 including mounting means connected to each end of the wire for maintaining the wire continuously in tension in the narrow passage as the temperature of the wire changes.

Claim 15

Apparatus according to claim 13 in which the mounting means comprises a separate spring biased mounting member connected to each end of the wire, each mounting member being adapted to move so its point of connection to the wire moves along the axis of the wire as the wire expands and contracts in response to temperature changes.

Claim 16

For use in a spirometer having means for recording the flow of breath exhaled or inhaled by a patient, apparatus for producing and detecting gas flow which is proportional to the flow of breath produced by the patient, the apparatus comprising a disposable flow tube having an opening through it for transmitting human breath; a transverse lateral channel opening into the tube; a lateral conduit having an opening through it, with one end communicating with the channel and the other end open to the atmosphere; means in the flow tube for aspirating gas flow from the atmosphere through the conduit and the channel and into the flow tube in response to the transmission of breath through the flow tube; and sensing means for detecting the aspirated gas flow in the lateral conduit, whereby the flow of breath transmitted through the flow tube is measured when the recording means is connected with the sensing means.

Claim 17

For use in a spirometer having means for recording the flow of breath exhaled or inhaled by a patient, apparatus for producing and detecting gas flow which is proportional to the flow of breath produced by the patient, the apparatus comprising a disposable flow tube having an opening through it for transmitting human breath; a transverse lateral channel opening into the tube; a lateral conduit having an opening through it, with one end communicating with the channel and the other end open to the atmosphere; means in the flow tube for aspirating gas flow from the atmosphere through the conduit and the channel and into the flow tube in response to the transmission of breath through the flow tube; and sensing means for detecting the aspirated gas flow in the lateral conduit, whereby the flow of breath transmitted through the flow tube is measured when the recording means is connected with the sensing means.

Claim 18

Apparatus according to claim 15 wherein the lateral conduit is releasably sealed to the flow tube.

Claim 19

Apparatus according to claim 15 wherein the means for aspirating gas flow comprises a constriction disposed within the flow tube to create a partial vacuum for withdrawing gas from the lateral conduit through the channel into the flow tube.

Claim 20

Apparatus according to claim 15 including a second transverse lateral channel opening into the flow tube for transmitting a steady flow of gas to the interior of the flow tube to bias the floW of breath through the flow tube.

Claim 21

Apparatus according to claim 15 in which the lateral conduit includes a body having an elongated narrow passage extending through it and opening to the atmosphere, the passage being adapted for communication with the transverse lateral channel; and in which the sensing means includes an elongated temperature-sensitive wire in the narrow passage for detecting gas flow through the passage.

Claim 22

Apparatus according to claim 19 in which the narrow passage extending through the body is open to the atmosphere at both ends, and in which the body includes a lateral channel transverse to the narrow passage and having one end opening into an intermediate portion of the narrow passage, the other end of the lateral channel opening into the lateral channel of the flow tube.

Claim 23

Apparatus according to claim 19 in which the diameter of the narrow passage is about 0.04 inch, and the diameter of the temperature-sensitive wire is about 0.0005 inch.

Claim 24

Apparatus according to claim 19 including mounting means at each end of the wire for maintaining the wire in tension as the temperature of the wire changes.

Claim 25

Apparatus according to claim 22 in which the mounting means comprises a separate resilient mounting member connected to each end of the wire, each mounting member being adapted to move so its point of connection to the wire moves along the axis of the wire as the wire expands and contracts in response to temperature changes.