Partial body plethysmograph for measuring human respiratory system impedance

[54] PARTIAL BODY PLETHYSMOGRAPHY FOR MEASURING HUMAN RESPIRATORY SYSTEM IMPEDANCE

[75] Inventor: Andrew C. Jackson, Brookline, Mass.

[73] Assignee: Trustees of Boston University, Boston, Mass.

[21] Appl. No.: 202,660

[22] Filed: Feb. 28, 1994

[51] Int. CI.6 A61B 5/08

[52] U.S. CI 128/721; 128/716

[58] Field of Search 128/721, 713,

128/734, 720, 716, 693, 719, 633, 724, 686, 688, 719, 713, 720, 721, 729, 693; 600/21; 248/393, 229; 297/313

[56] References Cited

U.S. PATENT DOCUMENTS

4,448,454 5/1984 Scott 297/313

5,323,994 6/1994 Shiffington et al 248/229

OTHER PUBLICATIONS

"Respiratory Transfer Impedance between 8 And 348 Hz In Guinea Pigs Before And After Bronchial Challenge," Jamil F. Sobh, Boston University, 1993, 64 pages excluding Appendices.

"Design And Clinical Use Of A Partial Body Plethysmograph For Measuring Transfer Impedance In Humans," Frederic T. Arbogast, Boston University, 1993, 77 pages excluding Appendices A-C.

"Total Respiratory Input and Transfer Impedances in Humans", R. Peslin et al., American Physiological Society, 1985, pp. 492-501.

"Reliability of Parameter Estimates From Models Applied to Respiratory Impedance Data", Kenneth R. Lutchen et al., American Physiological Society, 1987. pp. 403-413. "Impact of Frequency Range and Input Impedance on Airway-Tissue Separation Implied From Transfer Impedance",

Kenneth R. Lutchen et al., American Physiological Society, 1993, pp. 1089-1099.

"Confidence Bounds on Respiratory Mechanical Properties Estimated from Transfer Versus Input Impedance in Human Versus Dogs", Kenneth R. Lutchen et al., IEEE Transactions on Biomedical Engineering, vol. 39, No. 6, Jun. 1992, pp. 644-651.

"Inability to Separate Airway from Tissue Properties by Use of Human Respiratory Input Impedance", Kenneth R. Lutchen et al., American Physiological Society, 1990, pp. 2403-2412.

"Respiratory Transfer Impedance and Derived Mechanical
Properties of Conscious Rats" E. Oostveen et al., American
Physiological Society, 1992, pp. 1598-1607.
"Mechanical Properties Of The Respiratory System: A Study
In Humans And Rats By Forced Oscillations," Cornelia
Maria Allegonda Oostveen, Sep. 1991, pp. 7-121, 123 and
125.

Primary Examiner—Angela D. Sykes
Assistant Examiner— Stephen Huang
Attorney, Agent, or Firm—Baker & Botts

[57] ABSTRACT

A partial body plethysmograph is provided to enable accurate modeling of a human's respiratory system for input frequencies of up to about 96 Hz using transfer impedance measurements. One preferred embodiment comprises a container for sealingly enclosing a portion of the subject's body, a pressure source for generating pressure signals over a predetermined frequency range, an air flow sensor for measuring the flow of air supplied to the subject, a pressure sensor for measuring the pressure applied to the cavity of the subject and a processor for controlling the pressure source, for storing the measured air flow and pressure and for determining the respiratory system impedance of the subject. An eight element model is used by the processor to inversely model the transfer impedance data and thereby determined characteristics of the respiratory system of the subject.

18 Claims, 7 Drawing Sheets