Boxless measurement of thoracic gas volume
AssigneeMedical Graphics Corporation
InventorsMichael G. Snow, Steven D. James
Life of this patent
Estimating the term…
Abstract
A portable apparatus for measuring the thoracic lung volume of a patient without enclosing the patient in a sealed chamber, comprising first and second impedance belts, a flow meter, shutter and a microprocessor-based controller. The flow meter includes pressure transducers for measuring the change in volume and pressure as the patient respires therethrough. The change in thoracic cage volume of the patient's lungs is directly correlated with the change of impedance in the belts. The thoracic lung volume is then determined from a measured barometric pressure, the measured change in pressure and the measured volume change in the thoracic cage volume utilizing a correction factor to determine the thoracic cage volume.
Claims17
A portable apparatus for measuring a lung volume of a patient, said apparatus comprising:
- (a) detection means attached to a torso of the patient, for detecting a volume change in the lung volume of the patient during a respiratory cycle;
- (b) a flow meter including a mouthpiece having pressure transducers coupled thereto for sensing volume and pressure change during the respiratory cycle;
- and
- (c) a microprocessor-based controller electrically coupled to said detection means and said flow meter, said controller including calibration means for calibrating the apparatus and means for analyzing signals transmitted from said detection means and said flow meter and for calculating the lung volume of the patient from the analyzed signals, wherein a calibration of the apparatus depends upon a correlation between change in thoracic cage volume and change in volume sensed by the flow meter.
A portable apparatus for measuring a lung volume of a patient, said apparatus comprising:
- (a) detection means attached to a torso of the patient, for detecting a volume change in the lung volume of the patient during a respiratory cycle;
- (b) a flow meter including a mouthpiece having pressure transducers coupled thereto for sensing volume and pressure change during the respiratory cycle;
- (c) a shutter sealably coupled to an end of the mouthpiece;
- and
- (d) a microprocessor-based controller electrically coupled to said detection means and said flow meter, said controller including calibration means for calibrating the apparatus and means for analyzing signals transmitted from said detection means and said flow meter and for calculating the lung volume of the patient from the analyzed signals, wherein a calibration of the apparatus depends upon a correlation between change in thoracic cage volume and change in volume sensed by the flow meter.
A method of measuring the thoracic gas volume of a patient's lungs utilizing a noninvasive apparatus, said method comprising the steps of:
- (a) attaching a detection means to a torso of the patient, wherein said detection means detects a change in the lung volume of the patient;
- (b) measuring a change of thoracic cage volume during a patient's respiratory cycle;
- (c) determining the barometric pressure in an area near the patient;
- (d) measuring a change of pressure in a mouthpiece as the patient breathes through the mouthpiece;
- and
- (e) determining the thoracic gas volume from the measured change of thoracic cage volume, change of pressure in the mouthpiece and measured barometric pressure.
Dependencies are inferred from the claim text.