Method of detecting and predicting neurocardiogenic syncope

Abstract

A method of detecting an early onset of neurocardiogenic syncope in a patient uses respiratory functions as a predictor of the syncope. According to the method, at least one sample of baseline minute ventilation, tidal volume and respiratory rate of the patient is obtained. The detection unit is set to detect an increase in tidal volume and in minute ventilation over a predetermined respiratory period. The detecting unit also detects any rate of change in respiratory rate and sends a signal to a microprocessor to determine whether the increase in minute ventilation is a sole function of increased tidal volume. The impending syncope is diagnosed if variance in respiratory rate is less than 25% in relation to the sampled baseline during the predetermined period of time.

I claim: 
     
       1. A method of detecting an impending neurocardiogenic syncope in a patient, comprising the steps of:
 obtaining at least one sample of baseline minute ventilation, tidal volume and respiratory rate of the patient; 
 detecting an increase in tidal volume over a predetermined period of respiration; 
 detecting an increase in minute ventilation over said predetermined period of respiration; 
 detecting any change in respiratory rate over said predetermined period of respiration; 
 storing at least one data associated with the increase in minute ventilation; and 
 detecting impending syncope when 
 (a) the increase in minute ventilation is attributable to an increase in tidal volume; and 
 (b) the change in respiratory rate is less than 25% in relation to the at least one sampled baseline respiratory rate during the predetermined period of respiration, wherein the steps of detecting an increase in minute ventilation, detecting an increase in tidal volume, detecting any change in respiratory rate, and detecting impending syncope each occur, at least in part, in a microprocessor. 
 
     
     
       2. The method of  claim 1 , comprising a step of generating an alarm signal after the impending syncope is detected. 
     
     
       3. The method of  claim 1 , wherein the step of obtaining at least one sample of baseline minute ventilation, tidal volume, and respiratory rate of the patient is performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       4. The method of  claim 1 , wherein impending syncope is detected when the detected increase in tidal volume is more than a 75% increase from the baseline. 
     
     
       5. A non-transitory computer readable medium for storing instructions for performing the method of  claim 1  when executed. 
     
     
       6. A method of preventing neurocardiogenic syncope in operators of equipment, comprising the steps of:
 obtaining at least one sample of baseline minute ventilation, tidal volume and respiratory rate of the equipment operator; 
 detecting an increase in tidal volume over a predetermined period of respiration of said equipment operator; 
 detecting an increase in minute ventilation over said predetermined period of respiration of said equipment operator; 
 detecting any change in respiratory rate over said predetermined period of respiration of said equipment operator; 
 storing at least one data associated with the increase in minute ventilation; and 
 alerting the equipment operator of impending syncope when 
 (a) the increase in minute ventilation is attributable to an increase in tidal volume; and 
 (b) the change in respiratory rate is less than 25% in relation to the at least one sampled baseline respiratory rate during the predetermined period of respiration, wherein the steps of detecting an increase in minute ventilation, detecting an increase in tidal volume, and detecting any change in respiratory rate each occur, at least in part, in a microprocessor. 
 
     
     
       7. A method of preventing neurocardiogenic syncope in operators of equipment according to  claim 6  wherein the alert to the equipment operator comprises an audible alarm. 
     
     
       8. A method of preventing neurocardiogenic syncope in operators of equipment according to  claim 6  wherein the alert to the equipment operator comprises a vibratory alarm. 
     
     
       9. The method of  claim 6 , wherein the step of obtaining at least one sample of baseline minute ventilation, tidal volume, and respiratory rate of the equipment operator is performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       10. The method of  claim 6 , wherein the step of alerting the equipment operator of impending syncope is performed only when the detected increase in tidal volume is more than a 75% increase from the baseline. 
     
     
       11. A non-transitory computer readable medium for storing instructions for performing the method of  claim 6  when executed. 
     
     
       12. A method of detecting impending neurocardiogenic syncope in a patient, said method comprising:
 obtaining a sample baseline minute ventilation, tidal volume, and respiratory rate from the patient; 
 obtaining a second minute ventilation, tidal volume, and respiratory rate from the patient over a predetermined period of time; and 
 detecting impending syncope in the patient by 
 (a) detecting an increase in minute ventilation, attributable to an increase in tidal volume, between said second minute ventilation and said baseline minute ventilation; and 
 (b) detecting a change in respiratory rate between said second respiratory rate and said baseline respiratory rate of less than 25%, wherein the steps of detecting an increase in minute ventilation, detecting a change in respiratory rate, and detecting impending syncope each occur, at least in part, in a microprocessor. 
 
     
     
       13. The method of  claim 12 , comprising a step of storing at least one data associated with said increase in minute ventilation. 
     
     
       14. The method of  claim 12 , wherein the step of obtaining a sample baseline minute ventilation, tidal volume, and respiratory rate of the patient is performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       15. The method of  claim 12 , wherein the step of detecting impending syncope further comprises detecting if said second tidal volume is more than 75% above the baseline tidal volume. 
     
     
       16. A non-transitory computer readable medium for storing instructions for performing the method of  claim 12  when executed. 
     
     
       17. A method of detecting an impending syncope in a patient, comprising the steps of:
 obtaining at least one sample of baseline minute ventilation, tidal volume and respiratory rate of the patient;   detecting an increase in tidal volume over a predetermined period of respiration;   detecting an increase in minute ventilation over said predetermined period of respiration;   detecting any change in respiratory rate over said predetermined period of respiration;   storing at least one data associated with the increase in minute ventilation; and   detecting impending syncope when   (a) the increase in minute ventilation is attributable to an increase in tidal volume; and   (b) the change in respiratory rate is less than 25% in relation to the at least one sampled baseline respiratory rate during the predetermined period of respiration, wherein the steps of detecting an increase in minute ventilation, detecting an increase in tidal volume, detecting any change in respiratory rate, and detecting impending syncope each occur, at least in part, in a microprocessor.   
     
     
       18. The method of claim 17, comprising a step of generating an alarm signal after the impending syncope is detected. 
     
     
       19. The method of claim 17, wherein the step of obtaining at least one sample of baseline minute ventilation, tidal volume, and respiratory rate of the patient is performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       20. The method of claim 17, wherein impending syncope is detected when the detected increase in tidal volume is more than a 75% increase from the baseline. 
     
     
       21. A non-transitory computer readable medium for storing instructions for performing the method of claim 17 when executed. 
     
     
       22. A method of preventing loss of consciousness in operators of equipment, comprising the steps of:
 obtaining at least one sample of baseline minute ventilation, tidal volume and respiratory rate of the equipment operator;   detecting an increase in tidal volume over a predetermined period of respiration of said equipment operator;   detecting an increase in minute ventilation over said predetermined period of respiration of said equipment operator;   detecting any change in respiratory rate over said predetermined period of respiration of said equipment operator;   storing at least one data associated with the increase in minute ventilation; and   alerting the equipment operator of impending loss of consciousness when   (a) the increase in minute ventilation is attributable to an increase in tidal volume; and   (b) the change in respiratory rate is less than 25% in relation to the at least one sampled baseline respiratory rate during the predetermined period of respiration, wherein the steps of detecting an increase in minute ventilation, detecting an increase in tidal volume, and detecting any change in respiratory rate each occur, at least in part, in a microprocessor.   
     
     
       23. A method of preventing loss of consciousness in operators of equipment according to claim 22 wherein the alert to the equipment operator comprises an audible alarm. 
     
     
       24. A method of preventing loss of consciousness in operators of equipment according to claim 22 wherein the alert to the equipment operator comprises a vibratory alarm. 
     
     
       25. The method of claim 22, wherein the step of obtaining at least one sample of baseline minute ventilation, tidal volume, and respiratory rate of the equipment operator is performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       26. The method of claim 22, wherein the step of alerting the equipment operator of impending loss of consciousness is performed only when the detected increase in tidal volume is more than a 75% increase from the baseline. 
     
     
       27. A non-transitory computer readable medium for storing instructions for performing the method of claim 22 when executed. 
     
     
       28. A method of detecting impending syncope in a patient, said method comprising:
 obtaining a sample baseline minute ventilation, tidal volume, and respiratory rate from the patient;   obtaining a second minute ventilation, tidal volume, and respiratory rate from the patient over a predetermined period of time; and   detecting impending syncope in the patient by   (a) detecting an increase in minute ventilation, attributable to an increase in tidal volume, between said second minute ventilation and said baseline minute ventilation; and   (b) detecting a change in respiratory rate between said second respiratory rate and said baseline respiratory rate of less than 25%, wherein the steps of detecting an increase in minute ventilation, detecting a change in respiratory rate, and detecting impending syncope each occur, at least in part, in a microprocessor.   
     
     
       29. The method of claim 28, comprising a step of storing at least one data associated with said increase in minute ventilation. 
     
     
       30. The method of claim 28, wherein the step of obtaining a sample baseline minute ventilation, tidal volume, and respiratory rate of the patient is performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       31. The method of claim 28, wherein the step of detecting impending syncope further comprises detecting if said second tidal volume is more than 75% above the baseline tidal volume. 
     
     
       32. A non-transitory computer readable medium for storing instructions for performing the method of claim 28 when executed. 
     
     
       33. A method of detecting impending syncope in a patient having a minute ventilation comprised of tidal volume and respiratory rate, said method comprising:
 (a) detecting an increase in minute ventilation attributable to at least a 75 percent increase in tidal volume in the patient during a time period; and   (b) detecting a change in respiratory rate in the patient of less than 25% during said time period, and   (c) detecting impending syncope when conditions (a) and (b) are met;   
       wherein the steps of detecting an increase in minute ventilation, detecting a change in respiratory rate, and detecting impending syncope each occur, at least in part, in a microprocessor. 
     
     
       34. The method of claim 33, comprising a step of storing at least one data associated with said increase in minute ventilation. 
     
     
       35. The method of claim 33, wherein the steps of detecting an increase in minute ventilation and a change in respiratory rate of the patient are performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       36. A non-transitory computer readable medium for storing instructions for performing the method of claim 33 when executed. 
     
     
       37. A method of preventing loss of consciousness in a human subject having a minute ventilation comprised of tidal volume and respiratory rate, said method comprising:
 (a) detecting an increase in minute ventilation attributable to at least a 75 percent increase in tidal volume in the subject during a time period; and   (b) detecting a change in respiratory rate in the subject of less than 25% during said time period, and   (c) providing a signal to the subject configured to alert the subject of impending loss of consciousness when conditions (a) and (b) are met; wherein the steps of detecting an increase in minute ventilation, detecting a change in respiratory rate, and providing a signal to the subject each occur, at least in part, in a microprocessor.   
     
     
       38. The method of claim 37, comprising a step of storing at least one data associated with said increase in minute ventilation. 
     
     
       39. The method of claim 37, wherein the steps of detecting an increase in minute ventilation and a change in respiratory rate of the subject are performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       40. A non-transitory computer readable medium for storing instructions for performing the method of claim 37 when executed. 
     
     
       41. The method of claim 37, wherein the signal is selected from the group consisting of visual, auditory, vibratory signals and combinations thereof. 
     
     
       42. A method of cardiac pacing of a patient with a heart and a pacemaker operatively attached to the patient's heart, the patient having a minute ventilation comprised of tidal volume and respiratory rate wherein said method comprises:
 (a) detecting an increase in minute ventilation attributable to at least a 75 percent increase in tidal volume in the patient during a time period; and   (b) detecting a change in respiratory rate in the patient of less than 25% during said time period, and   (c) delivering pacing pulses to the patient's heart when conditions (a) and (b) apply; and   
       wherein the steps of detecting an increase in minute ventilation and detecting a change in respiratory rate, each occur, at least in part, in a microprocessor. 
     
     
       43. The method of claim 42, comprising a step of storing at least one data associated with said increase in minute ventilation. 
     
     
       44. The method of claim 42, wherein the steps of detecting an increase in minute ventilation and a change in respiratory rate of the subject are performed by measuring transthoracic impedance or directly by exhaled volumes. 
     
     
       45. A non-transitory computer readable medium for storing instructions for performing the method of claim 42 when executed.