Method and system for monitoring ventilations and compressions delivered to a patient

• US 20060015044A1
• Filed: 07/14/2005
• Published: 01/19/2006
• Est. Priority Date: 07/15/2004
• Status: Abandoned Application

• Current Assignee: Laerdal Medical AS (Laerdal Medical Corporation)
• Original Assignee: Laerdal Medical AS (Laerdal Medical Corporation)
• Inventors: Nysaether, Jon, Myklebust, Helge, Eilevstjonn, Joar, Stavland, Mette, Tellnes, Geir Inge
• Application Number:
  US11/180,912
• Publication Number:
  US 20060015044A1
• Time in Patent Office: Days
• US Class Current: 601/41
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured

Abstract

Method and system for monitoring the ventilation of a patient, especially during chest compressions, comprising the steps of: essentially continuously measuring the impedance in the patients chest using at least two electrodes coupled to the patients chest, said impedance measurements being performed by applying an alternating current or voltage to at least two of said electrodes and measuring the impedance between at least two of said electrodes, measuring chosen parameters affecting said impedance measurements, e.g. chest compressions, and analyzing the impedance measurements for detection and characterizing of impedance variations from ventilations, said analysis including the removal of the effects said chosen parameters.

Claims

1. Method for monitoring the ventilation of a patient, especially during chest compressions, comprising the steps of:

essentially continuously measuring the impedance in the patients chest using at least two electrodes coupled to the patients chest, said impedance measurements being performed by applying an alternating current or voltage to at least two of said electrodes and measuring the impedance between at least two of said electrodes,

measuring chosen parameters affecting said impedance measurements, e.g. chest compressions, and

analyzing the impedance measurements for detection and characterizing of impedance variations from ventilations, said analysis including the removal of the effects said chosen parameters.

2. Method according to claim 1, wherein said chosen parameters includes movements applied to the patients chest and calculating, said analysis including the generation of an adaptive filter from said measured chosen parameters for removing the effects on the impedance from said measured movements.

3. Method according to claim 2, wherein the calculations of the adaptive filter also comprising the measuring of a force applied to the chest.

4. Method according to claim 2, wherein the calculations of the adaptive filter also comprising the measuring of the acceleration applied to the chest at a certain point.

5. Method according to claim 2, wherein the movement of the patients chest and back is measured and difference in movement and thus to distinguish between general movements of the patient and movements applied to the chest, e.g. for CPR treatment.

6. Method according to claim 1 also comprising measuring the applied force on the chest and said analysis also comprises detecting peak minimum values of the applied force, so as to detect whether the pressure has been completely released from the chest.

7. Ventilation monitoring system for monitoring the ventilation of a patient, comprising:

at least two electrodes adapted to be positioned on a patients chest coupled to impedance measuring means for measuring the impedance in the patients chest, said impedance measurements being performed by applying an alternating current or voltage to said electrodes and measuring the impedance between them,

measuring means for measuring at least one chosen parameter affecting the measured impedance in a per se known way, and

a processing unit for providing a signal indicative of the ventilation of the patient from said impedance movement, said processing unit also being adapted to remove the effects of said measured chosen characteristics from said ventilation signal.

8. System according to claim 7 also comprising a movement sensor position on the patients chest for measuring the movement of the patients chest and coupled to said processing means for calculating and applying an adaptive filter to said measured impedance, said filter being adapted to remove the effects of the movements from said impedance signal.

9. System according to claim 8, also comprising a force sensor measuring the force applied to the chest, e.g. during CPR and coupled to said processing unit, said adaptive filter also including the signals from said force sensor.

10. System according to claim 8, also comprising an acceleration sensor measuring the acceleration applied to a certain point on the chest, e.g. during CPR, and coupled to said processing unit, said adaptive filter also including the signals from said acceleration sensor.

11. System according to claim 8, also comprising a second movement sensor coupled to said processing unit and positioned on the patients back for measuring the movements of the patient, said processing unit providing a difference signal indicative of the chest movement relative to the back, and thus the part of the movement affecting the impedance signal.

12. System according to claim 7 also comprising a force sensor coupled to said processing unit, said processing unit being adapted to monitor the minimum peak values of said force signal so as to whether the pressure has been completely released from the chest.

13. System for controlling CPR activity comprising sensors for measuring force and movement applied to the chest of a patient, comprising processing means for calculating compression depth from said applied movement, wherein said processing unit is provided with means for comparing the measured force and calculated compression depth with respective chosen values, and for providing or withholding feedback based in the measured values, e.g.by withholding feedback related to insufficient compression depths if the measured force exceeds the corresponding chosen value while said calculated compression depth is less than said chosen value.

14. System for controlling CPR activity comprising sensors for measuring force and movement applied to the chest of a patient, comprising processing means for calculating compression depth from said applied movement, also comprising a second movement arranged to follow the movement of the patients back, said processing means being adapted to calculate the difference in movement between the two sensors.