Device and associated methods for simultaneous measurement of pulmonary ventilation and metabolic rate

1 . A system for simultaneous measurement of pulmonary ventilation and metabolic rate, comprising:

a dual-chamber plethysmograph device including:

a body defining a dual chamber configuration, including:

a first chamber configured to receive a body of a test subject with a head of the test subject extending outside the first chamber, and

a second chamber defining a size greater than the first chamber and surrounding at least a portion of the first chamber, the second chamber including gas outflow ports,

a pneumotach fluidly coupled to the first chamber that generates an airflow signal indicative of pulmonary ventilation of the test subject; and

a gas analyzer pump including O 2 and CO 2 sensors fluidly coupled to at least one of the gas outflow ports of the second chamber and configured to pull air through the dual-chamber plethysmograph and detect a rate of flow and concentrations of O 2 and CO 2 gas exiting the second chamber to measure a metabolic rate of the test subject.

2 . The system of claim 1 , further comprising a vest sized for a neonatal rodent including one or more electrodes for obtaining a measurement of EKG to obtain heart rate of the test subject, wherein lead wires from the electrodes pass through holes in at least one of the first chamber and the second chamber to an external amplifier.

3 . The system of claim 1 , further comprising a thermocouple probe attached to a control unit that maintains chamber temperature of the device by controlling a heat lamp.

4 . The system of claim 1 , wherein two ports of the pneumotach are attached to positive and negative ports of a pressure transducer.

5 . The system of claim 1 , wherein the gas analyzer is configured to pull air through the second chamber for open circuit measurement of metabolic rate.

6 . A device for simultaneous and improved measurement of pulmonary ventilation and metabolic rate, comprising:

a body defining a dual chamber configuration, including:

a first chamber configured for a head-out plethysmograph, and

a second chamber defining a size greater than the first chamber, the first chamber being disposed within the second chamber along a channel of the second chamber,

the second chamber including

at least one gas inflow port and at least one gas outflow port configured to permit a bias flow of gas through the second chamber,

a gas analyzer fluidly coupled to the at least one gas outflow port of the second chamber, the gas analyzer including O 2 and CO 2 sensors that determine a metabolic rate of a test subject from gas exiting the second chamber, and

at least one sensor associated with the first chamber and configured to generate a signal indicative of pulmonary ventilation of the test subject while the metabolic rate is determined from the gas analyzer.

7 . The device of claim 6 , further comprising:

a plurality of ports defined along the second chamber to accommodate connection to tubing for gas inflow and outflow.

8 . The device of claim 6 , further comprising:

a vest including one or more electrodes for obtaining a measurement of EKG to obtain heart rate of the test subject, the vest being configured to be worn by the test subject while the test subject is positioned within the first chamber.

9 . The device of claim 6 , wherein the body is configured to position the test subject such that a head of the test subject is positioned outside the first chamber but sealed from the environment by nature of the second chamber with exception of a predetermined bias flow of gas fed to the body.

10 . The device of claim 6 , wherein the body is configured for air to be pulled through the second chamber an O 2 and CO 2 analyzer for open circuit measurement of metabolic rate of the test subject.

11 . The device of claim 6 , wherein the body is configured to receive a Luer lock fitting in communication with tubing to interconnect the body with a pneumotachometer for pulmonary function testing.

12 . The device of claim 6 , further comprising one or more holes formed along the body to accommodate EKG wires and thermocouple.

13 . The device of claim 6 , further comprising an access slot formed into an open end of the second chamber that accommodates the first chamber to be inserted within the second chamber along the channel.

14 . The device of claim 6 , further comprising inflow and outflow ports defined along the body for feeding gas through the body.

15 . The device of claim 6 , further comprising one or more recording devices including a thermocouple probe attached to a control unit that maintains chamber temperature of the device by controlling a heat lamp.

16 . A method for improved measurement of pulmonary ventilation and metabolic rate, comprising:

positioning a test subject in a first chamber configured for a head-out plethysmograph so that a head of the test subject extends outside the first chamber;

positioning the first chamber within a channel defined by a second chamber to define a dual chamber configuration with the second chamber surrounding at least a portion of the first chamber;

flowing a bias gas through the second chamber between at least one gas inflow port and at least one gas outflow port of the second chamber;

measuring a respiratory signal associated with the first chamber to obtain a pulmonary ventilation parameter of the test subject; and

measuring O 2 and CO 2 concentrations of gas exiting the second chamber at the at least one gas outflow port with a gas analyzer and determining a metabolic rate of the test subject from the measured O 2 and CO 2 concentrations while the pulmonary ventilation parameter is measured.

17 . The method of claim 16 , further comprising:

forming an access slot along an open end of the second chamber to accommodate insertion of the first chamber within the channel of the second chamber.

18 . The method of claim 17 , further comprising positioning a lid along the open end of the second chamber adjacent the access slot to seal the first chamber within the channel of the second chamber.

19 . The method of claim 16 , further comprising forming a plurality of ports along the second chamber to accommodate connection to tubing for gas inflow and outflow.

20 . The method of claim 16 , further comprising providing a vest including a plurality of electrodes positioned along the vest for monitoring a heart rate of the test subject positioned within the second chamber.