Detection and classification of breathing patterns

1. A respiratory analysis system for monitoring a respiratory variable for a patient, the system comprising:

a sensor array for accommodating a patient to be in contact therewith, the array having a plurality of independent sensors for measuring respiratory movement at different locations on the patient to generate a set of independent respiratory movement signals; and a processor to receive and process said movement signals to derive a classification of individual breaths using, for each breath, at least one of a respective phase and an amplitude of each movement signal within the set for that breath, wherein the processor is operable to determine the period, and thus the frequency, of a breath from the set of signals, and for each sensor, to determine a vector defining at least one of the amplitude and the phase of the breath frequency component present in the signal, the set of vectors being the breath classification.

2. A system as claimed in claim 1 , further comprising a pre-processor to receive said movement signals, and to pre-process them by at least one of equalizing each movement signal and deconvolving spatially the movement signals, thereby isolating each signal from all others and pass said pre-processed signals to said processor.

3. A system as claimed in claim 1 , further including at least one of output and storage means for at least one of outputting and storing the respiratory variable.

4. A respiratory analysis system as claimed in claim 1 , wherein the processor is further operable diagnostically to compare said breath classifications between at least two breaths to detect altered breathing patterns.

5. A respiratory analysis system for monitoring a respiratory variable for a patient, the system comprising:

a sensor array for accommodating a patient to be in contact therewith, the array having a plurality of independent sensors for measuring respiratory movement at different locations on the patient to generate a set of independent respiratory movement signals; and a processor to receive and process said movement signals to derive a classification of individual breaths using, for each breath, at least one of a respective phase and an amplitude of each movement signal within the set for that breath; wherein the processor is further operable diagnostically to compare said breath classifications between at least two breaths to detect altered breathing patterns.

6. A respiratory analysis system as claimed in claim 5 , wherein the comparison is performed by a cross-correlation of at least one of the amplitude and the phase of the respective set of signals.

7. A respiratory analysis system as claimed in claim 5 , wherein the comparison is performed by a cross-correlation of the respective vectors of the breaths.

8. A respiratory analysis system as claimed in claim 7 , wherein the cross-correlation is performed by a scalar multiplication of and subsequent summation of corresponding pairs of sensor amplitude and/or phase vectors of the two breaths being compared.

9. A method for monitoring at least one respiratory variable for a patient, the method comprising:

measuring respiratory movement at different locations on a patient to generate a set of independent respiratory movement signals; and

processing said movement signals to derive a classification of individual breaths using, for each breath, at least one of a respective phase and an amplitude of each movement signal with the set for that breath,

whereby the processing comprises determining the period, and thus the frequency, of a breath from the set of signals, and deriving the breath classification from a vector defining at least one of the amplitude and the phase of the breath frequency component present in the signal.

10. A method as claimed in claim 9 , whereby said comparison comprises cross-correlating at least one of the amplitudes and the phases of the respective set of signals.

11. A method as claimed in claim 9 , further comprising comparing two said classifications to detect altered breathing patterns.

12. A method for monitoring at least one respiratory variable for a patient, the method comprising:

measuring respiratory movement at different locations on a patient to generate a set of independent respiratory movement signals;

processing said movement signals to derive a classification of individual breaths using, for each breath, at least one of a respective phase and an amplitude of each movement signal with the set for that breath; and

comparing two said classifications to detect altered breathing patterns.

13. A method as claimed in claim 12 , whereby said comparison comprises cross-correlating at least one of the amplitudes and the phases of the respective set of signals.

14. A method as claimed in claim 13 , whereby the cross-correlation comprises the scalar multiplication of and subsequent summation of corresponding pairs of at least one of sensor amplitude and phase vectors of the two breaths being compared.

15. A method for determining whether two breaths are similar comprising:

monitoring a plurality of independent patient movement signals;

identifying the portions of said signals which correspond to each breath;

for said portions, calculating the phase and amplitude of corresponding periodic functions;

determining a vector for each breath in accordance with said phases and amplitudes;

calculating a measure of the correlation between the vectors for the two breaths; and

if said measure is greater than a threshold, determining that the breaths are similar.

16. A method as claimed in claim 15 , wherein said correlation is the dot product of the two vectors.

17. A method as claimed in claim 16 , wherein said threshold is 0.9.

18. A method for determining whether two breaths are different comprising:

monitoring a plurality of independent patient movement signals;

identifying the portions of said signals which correspond to each breath;

for said portions, calculating the phase and amplitude of corresponding periodic functions;

determining a vector for each breath in accordance with said phases and amplitudes;

calculating a measure of the correlation between the vectors for the two breaths; and

if said measure is less than a threshold, determining that the breaths are different.

19. A method as claimed in claim 18 , wherein said correlation is the dot product of the two vectors.

20. A method as claimed in claim 19 , wherein said threshold is 0.6.