Method and apparatus for indicating the absence of a pulmonary embolism in a patient
First Claim
1. :
- A method for determining an embolic condition of a patient, said method comprising the steps of;
(a) measuring the amount of CO2 expired by the patient during the expiration of breathing gases by the patient;
(b) measuring the volume (V) of breathing gases expired during the expiration of breathing gases by the patient;
(c) determining a relationship between changes in the amount of expired CO2 and a change in breathing gas volume in an alveolar expiration phase of patient expiration;
(d) measuring an amount of CO2 in the lungs of the patient at the end of expiration;
(e) measuring the amount of CO2 in the blood of the patient;
(f) determining the difference between the amount of CO2 in the blood and the amount of CO2 in the lungs of the patient at the end of expiration; and
(g) establishing a relationship between the determination of step (f) and the determination of step (c) to produce a quantity for use in determining the embolic condition of the patient.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and apparatus for determining the presence or absence of a pulmonary embolism (PE) in a patient. The breathing gas CO2 partial pressure (PCO2) during the expiration of breathing gases by the patient, the end tidal (EtCO2), CO2 partial pressure, and the CO2 partial pressure (PaCO2) of the blood are measured. The volume (V) of breathing gases expired during the expiration of breathing gases by the patient is also measured and a relationship between changes in breathing gas CO2 partial pressure (PCO2) and changes in breathing gas volume (V) in an alveolar expiration phase of patient expiration is determined. The difference between the blood CO2 partial pressure (PaCO2) and the end expiration CO2 partial pressure is divided by the relationship between PCO2 and V produce a quantity which is compared to a threshold value. If the quantity is below the threshold value, the absence of a pulmonary embolism is indicated.
30 Citations
37 Claims
-
1. :
- A method for determining an embolic condition of a patient, said method comprising the steps of;
(a) measuring the amount of CO2 expired by the patient during the expiration of breathing gases by the patient;
(b) measuring the volume (V) of breathing gases expired during the expiration of breathing gases by the patient;
(c) determining a relationship between changes in the amount of expired CO2 and a change in breathing gas volume in an alveolar expiration phase of patient expiration;
(d) measuring an amount of CO2 in the lungs of the patient at the end of expiration;
(e) measuring the amount of CO2 in the blood of the patient;
(f) determining the difference between the amount of CO2 in the blood and the amount of CO2 in the lungs of the patient at the end of expiration; and
(g) establishing a relationship between the determination of step (f) and the determination of step (c) to produce a quantity for use in determining the embolic condition of the patient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
- A method for determining an embolic condition of a patient, said method comprising the steps of;
-
27. :
- A method for determining the presence or absence of a pulmonary embolism (PE) in a patient, said method comprising the steps of;
(a) measuring breathing gas CO2 partial pressure (PCO2) during the expiration of breathing gases by the patient;
(b) measuring the volume (V) of breathing gases expired during the expiration of breathing gases by the patient;
(c) determining the relationship between changes in breathing gas CO2 partial pressure (PCO2) and changes in breathing gas volume (V) in an alveolar expiration phase of patient expiration;
(d) measuring the CO2 partial pressure (EtCO2) of the breathing gases of the patient at the end of expiration;
(e) measuring the CO2 partial pressure in the blood of the patient (PaCO2);
(f) determining the difference between the blood CO2 partial pressure (PaCO2) and the end expiration CO2 partial pressure (EtCO2); and
(g) dividing the CO2 partial pressure difference determined in step (f) by the relationship determined in step (c) to produce a quantity;
(h) establishing a threshold value for the quantity produced in step (g);
(i) comparing the quantity produced in step (g) to the threshold value; and
(j) indicating the absence of a pulmonary embolism when the quantity produced in step (g) is below the threshold value.
- A method for determining the presence or absence of a pulmonary embolism (PE) in a patient, said method comprising the steps of;
-
28. :
- An apparatus for determining an embolic condition of a patient, said apparatus comprising;
(a) means for measuring the amount of CO2 expired by the patient during the expiration of breathing gases by the patient and the amount of CO2 in the lungs of the patient at the end of expiration;
(b) means for measuring the volume (V) of breathing gases expired during the expiration of breathing gases by the patient;
(c) means for determining a relationship between changes in the amount of expired CO2 and a change in breathing gas volume in an alveolar expiration phase of patient expiration;
(d) means measuring an amount of CO2 in the blood of the patient;
(e) means for determining the difference between the amount of CO2 in the blood and the amount of CO2 in the lungs of the patient at the end of expiration; and
(f) means for establishing a relationship between the determination by means (f) and the determination by means (c) to produce a quantity for use in determining the embolic condition of the patient. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36)
- An apparatus for determining an embolic condition of a patient, said apparatus comprising;
-
37. :
- An apparatus for determining the presence or absence of a pulmonary embolism (PE) in a patient, said apparatus comprising;
(a) means for measuring breathing gas CO2 partial pressure (PCO2 during the expiration of breathing gases by the patient and the CO2 partial pressure (EtCO2) of the breathing gases at the end of expiration;
(b) means for measuring the volume (V) of breathing gases expired during the expiration of breathing gases by the patient;
(c) means determining the relationship between changes in breathing gas CO2 partial pressure (PCO2) and changes in breathing gas volume (V) in an alveolar expiration phase of patient expiration;
(d) means for measuring the CO2 partial pressure in the blood of the patient (PaCO2);
(e) means for determining the difference between the blood CO2 partial pressure (PaCO2) and the end expiration CO2 partial pressure (EtCO2); and
(f) means for dividing the CO2 partial pressure difference determined in step (f) by the relationship determined by means (c) to produce a quantity;
(g) means for establishing a threshold value for the quantity produced by means (g);
(h) means for comparing the quantity produced by means (g) to the threshold value; and
(i) means for indicating the absence of a pulmonary embolism when the quantity produced by means (f) is below the threshold value.
- An apparatus for determining the presence or absence of a pulmonary embolism (PE) in a patient, said apparatus comprising;
Specification