Patent Abstract:
The present invention includes a respiratory monitor that improves patient safety through the use of highly responsive monitors and displays highly visible to all clinical personnel even in the absence or failure of an alarm display. The display can be positioned so that clinicians do not have to look away from the patient to view the output of the respiratory monitor. The respiratory monitoring system alerts clinicians of potential problems while automatically taking steps to gather additional information and place an integrated drug delivery system in a safe state (e.g., step down or deactivation) in addition to providing a real-time visual indicator of respiratory rate and estimated tidal volume or respiratory effort and effect. Multiple thresholds that trigger corresponding indicators such as color-coded LEDs provide a quantized display of respiratory effort and effect while also providing a certain level of redundancy. The respiratory effort and effect can also be displayed by the intensity of the LEDs. Other arrays of LEDS provide graded levels of alarms.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 60/430,088, “Respiratory Monitoring Systems and Methods,” filed Dec. 2, 2002, which is hereby incorporated by reference. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         REFERENCE TO A “MICROFICHE APPENDIX” 
         [0003]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    1. Field of the Invention  
           [0005]    The present invention relates, in general, to respiratory monitoring and, more particularly, to respiratory monitoring associated with medical devices.  
           [0006]    2. Description of the Related Art  
           [0007]    Every year a significant number of patients suffer severe complications or death due to inadequate, improper or inaccurate respiratory monitoring. Unaided by sensors, it is difficult in some critical circumstances, for even the most highly trained clinician to ascertain whether a patient is moving sufficient air or gas for proper alveolar gas exchange. In an attempt to improve patient safety, a number of respiratory monitoring systems have been developed. However, such systems have not fully met the safety needs of patients, particularly in settings such as sedation and analgesia of the conscious and/or spontaneously breathing patient, as evidenced by continuing reports of negative patient episodes due to inadequate, improper or inaccurate respiratory monitoring.  
           [0008]    Capnometry systems have been used with some success in assessing the respiration of a patient by evaluating the partial pressure or percent concentration of exhaled carbon dioxide. When using these systems, carbon dioxide production is implicitly correlated to oxygen consumption via the respiratory quotient, which usually has a value of 0.8. Mainstream capnometers consist of a small infrared gas analysis bench that is mounted directly in the patient&#39;s respiratory path providing real-time information regarding the CO 2  level in the patient&#39;s respiration. However, the sampling cell used by mainstream capnometers is, in general, relatively bulky and heavy. The sample cell of a mainstream capnometer can be in the way when mounted in the respiratory path, e.g., in front of a patient&#39;s face. Sidestream capnometers have a pump that continuously aspirates gas samples from the patient&#39;s respiratory path, typically at a sampling flow rate of about 200 ml/min, via a sampling tube that carries the sample gas to a gas analysis bench. The finite transport time from the sampling site to the gas analysis bench introduces an undesirable time lag. When a patient stops breathing, the measured and displayed CO 2  level becomes a flat line at zero mm Hg because there are no exhalations containing CO 2 . Further, a patient&#39;s inhalation generally draws room air (0.003% CO 2 ) or gas having zero or negligible carbon dioxide concentration such that the inspired CO 2  is for all intents and purposes zero. Thus, it is difficult to instantly know during inspiration whether a patient is simply inhaling or has stopped breathing all together. The need has therefore arisen for a respiratory monitoring system that provides real-time, unambiguous and instantaneous information regarding a patient&#39;s respiratory status and phase of respiration.  
           [0009]    Many current respiratory monitoring systems require the use of a face mask, where the mask encapsulates the nose and mouth of a patient to create a sealed region. Different designs of such systems utilize different sensors such as temperature sensors, humidity sensors, and flow meters. Many patients may find face masks to be uncomfortable and anxiety inspiring. In addition, many procedures require oral access (e.g., esophogastroduodenoscopy and oral surgery) which makes sealing face masks inapplicable. Also, the continuous fresh gas flow from an anesthesia machine will dilute the CO 2  in the additional deadspace created by the facemask, resulting in artificially low CO 2  levels. On the other hand, existing respiratory monitoring systems without a sealed facemask may not provide respiratory data of sufficient clinical accuracy. The need has therefore arisen for a respiratory monitor that functions independently of a sealed face mask and monitors respiration with sufficient clinical accuracy.  
           [0010]    Existing respiratory monitors are generally integrated with alarm systems, where a clinician is alerted to the presence of respiratory compromise by visual and/or audio alarms. In an operating or procedure room environment, where there are multiple alarm sources and auditory and visual stimuli, it may take a while before the attending clinician is able to determine the cause of the alarm and take appropriate action to remedy the situation. In critical circumstances, rapid diagnosis and intervention can prevent morbid complications. The need has therefore arisen for a respiratory monitoring system that simultaneously alerts the attending clinician of a potential problem while automatically taking steps to gather additional information and placing other aspects of a drug delivery system into a safe state.  
           [0011]    Existing alarm algorithms or mechanisms generally alert the attending clinician in the event of an alarm condition. In the event of malfunction of the alarm mechanism itself, e.g., failure of the buzzer for an audible alarm or the LED (light emitting diode) for a visual alarm, an alarm will not be generated even though a critical patient condition is present. The lack of an alarm may lull the clinician into a false sense of security, rendering it even more difficult for the clinician to detect the critical patient condition and take timely corrective action. The need has therefore arisen for an alarm and monitoring system that provides real-time monitoring of respiration throughout the duration of a procedure, where a clinician may still be able to readily ascertain whether respiration has been compromised, even in the absence or failure of an alarm mechanism.  
           [0012]    False negative alarm conditions may occur with existing respiratory monitoring systems; that is, respiratory compromise may be present while no alarm is generated to alert the clinician of this condition. For example, existing alarms may be set to warn the clinician if a patient does not take a sufficient number of substantial breaths within a pre-determined time window. By taking shallow but frequent breaths, it may be possible for a patient to meet or exceed the fixed and individual alarm threshold for each monitored parameter such that no alarm is generated even though respiration is compromised. The need has therefore arisen for a respiratory monitoring system that provides anthropomorphic, hierarchic and graded alarms based on varying patient conditions, where, for example, one tier of alarms may be correlated to patient conditions that require increased watchfulness and a second tier of alarms may be correlated to more serious patient conditions that require deactivation of drug delivery. An anthropomorphic alarm paradigm is generally less rigid and more context sensitive because it attempts to emulate human behavior, mental processes and experience. The need has further arisen for a respiratory monitoring system that provides a real-time visual indicator of respiratory rate and estimated tidal volume.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention satisfies the above needs by providing a respiratory monitor that improves patient safety in the absence of a sealed face mask. The present invention further provides an integrated respiratory monitor with additional patient monitors and drug administration systems, where the integrated system automatically converts the system to a safe state in the event of a significant respiratory compromise. The present invention even further provides a respiratory monitoring system that operates in real time to allow for immediate responses to critical patient episodes. The present invention also provides a respiratory monitoring system that displays real-time information related to a patient&#39;s respiratory condition and uses anthropomorphic and safety-biased alarm and intervention paradigms to minimize distracting alarms and time and motion expenditure. The present invention further provides a respiratory monitor integral with an alarm and visual monitoring system that has a high degree of visibility, where a number of attending clinicians can easily monitor real-time information related to a patient&#39;s respiratory condition. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 illustrates a block diagram depicting one embodiment of a respiratory monitoring system for use with a sedation and analgesia system in accordance with the present invention;  
         [0015]    [0015]FIG. 2 illustrates a block diagram of a more detailed view of one embodiment of a respiratory monitoring system in accordance with the present invention;  
         [0016]    [0016]FIG. 3 illustrates one embodiment of a nasal interface in accordance with the present invention;  
         [0017]    [0017]FIG. 4 illustrates one embodiment of an ear mount in accordance with the present invention;  
         [0018]    [0018]FIG. 5 illustrates one embodiment of a support band in accordance with the present invention;  
         [0019]    [0019]FIG. 6 illustrates one embodiment of a method for pressure waveform analysis and segmentation depicting positive pressure thresholds and negative pressure thresholds in accordance with the present invention;  
         [0020]    [0020]FIG. 7 illustrates one embodiment of an LED display in accordance with the present invention;  
         [0021]    [0021]FIG. 8 illustrates one embodiment of a method for employing a respiratory monitoring system in accordance with the present invention; and  
         [0022]    [0022]FIG. 9 illustrates one embodiment of a method for employing a respiratory monitoring system having alarm conditions in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    [0023]FIG. 1 illustrates a block diagram depicting one embodiment of the present invention comprising a sedation and analgesia system  22  having user interface  12 , software controller  14 , peripherals  15 , power supply  16 , external communications  10 , respiratory monitoring  11 , O 2  delivery  9  with manual bypass  20  and scavenger  21 , patient interface  17 , and drug delivery  19 , where sedation and analgesia system  22  is operated by user  13  in order to provide sedation and/or analgesia to patient  18 . Several embodiments of sedation and analgesia system  22  are disclosed and enabled by U.S. patent application Ser. No. 09/324,759, filed Jun. 3, 1999 and incorporated herein by reference in its entirety. It is further contemplated that respiratory monitoring  11  be used in cooperation with sedation and analgesia systems, anesthesia systems and integrated patient monitoring systems, independently, or in other suitable capacities. Embodiments of patient interface  17  are disclosed and enabled by U.S. patent application Ser. No. 09/592,943, filed Jun. 12, 2001 and U.S. patent application Ser. No. 09/878,922 filed Jun. 13, 2001 which are incorporated herein by reference in their entirety.  
         [0024]    [0024]FIG. 2 illustrates a block diagram depicting a more detailed view of one embodiment of respiratory monitoring  11 , controller  14 , drug delivery  19 , and patient interface  17 . In one embodiment of the present invention, patient interface  17  comprises nasal cannula  30  and visual display  31 . Nasal cannula  30  may deliver oxygen to patient  18 , sample the partial pressure or percent concentration of carbon dioxide, and sample nasal pressure associated with inhalation and exhalation. Visual display  31  may be a series of light emitting diodes (LEDs) capable of visually displaying information related to patient respiration. The LEDs may be designed to be reusable with disposable covering lenses. The disposable covering lenses may be designed to amplify the intensity of the LEDs and may also be of shapes (such as arrows or arrowheads) that indicate the direction of gas flow during inhalation and exhalation.  
         [0025]    Respiratory monitoring  11  may comprise sensor  32 , analog digital input output (ADIO) device  29 , and computer programmable logic device (CPLD)  33 . Sensor  32  may be a pressure sensor, a humidity sensor, a thermistor, a flow meter, or any other suitable sensor for measuring respiration of patient  18 . In one embodiment of the present invention, sensor  32  is a Honeywell DC series differential pressure sensor capable of monitoring from +1 inch to −1 inch of water pressure. The present invention comprises a plurality a sensors that may be associated with individual nares, oral monitoring, both nasal and oral monitoring, intra-vascular monitoring, or other means of employing sensors commonly known in the art.  
         [0026]    Still referring to FIG. 2, respiratory monitoring  11  further comprises tubing  34  which interfaces with cannula  30  and sensor  32  in order to measure the pressure variations caused by respiration of patient  18 . Tubing  34  may be constructed of any suitable material for providing sensor  32  with accurate pressure measurements from cannula  30  such as, for example, polyvinyl tubing. The characteristics of tubing  34  such as internal diameter, wall thickness and length may be optimized for transmission of the pressure signal. Sensor  32  may output analog signals, where ADIO device  29  converts the analog signals to digital signals before they are transmitted to controller  14  via connection  36 . Controller  14  may process the digital signals into respiratory information. Digital signals relating to patient respiration may then be transmitted via connection  38  to CPLD  33 , where programming associated with CPLD  33  then controls visual display  31  via connection  39  based on the information contained in the digital signals. In some embodiments of the invention, any of controller  14 , ADIO  29 , CPLD  33 , and sensor  32  may be included or excluded in different combinations or permutations on a single integrated circuit.  
         [0027]    In one embodiment of the present invention, controller  14  may control drug delivery  19  based on data received from ADIO device  29 , where such data indicates a potentially dangerous patient episode. Controller  14  may be programmed to deactivate drug delivery  19  or reduce drug delivery rate associated with drug delivery  19  in the event of a negative patient episode, or reactivate drug delivery upon receipt of data indicating that patient  18  is no longer experiencing a potentially life-threatening event.  
         [0028]    [0028]FIG. 3 illustrates one embodiment of nasal interface  40  associated with cannula  30  (FIG. 2). In one embodiment of the present invention, nasal interface  40  comprises first nasal port  41 , second nasal port  42 , oxygen delivery port  44 , first nasal capnography port  48 , first pressure sensor port  43 , second nasal capnometry port  47 , second pressure sensor port  45 , oral capnometry port  49 , and oral port  46 . First nasal port  41  and second nasal port  42  may be designed for placement within or adjacent to the nares of patient  18 . An in-house or portable oxygen supply may be connected to oxygen delivery port  44 , such that oxygen may be delivered to patient  18  through first nasal port  41  and second nasal port  42  or a grid of ports.  
         [0029]    Embodiments of the present invention may comprise monitoring a single nare of patient  18 , monitoring multiple nares in the absence of an oral monitor, monitoring patient  18  orally in the absence of nasal monitors, or other suitable monitoring combinations. Oxygen delivery may be optional, orally delivered, nasally delivered, or delivered both orally and nasally. The present invention further comprises a plurality of oxygen delivery ports, where oxygen may be delivered to the nares and/or mouth. It is further consistent with the present invention to deliver a plurality of gases through nasal interface  40  such as, for example, nitrous oxide. A further embodiment of the present invention comprises monitoring a plurality of patient parameters such as, for example, inspired and/or expired oxygen and/or CO 2  concentration or partial pressure via nasal interface  40 .  
         [0030]    Still referring to FIG. 3, nasal interface  40  may be constructed from nylon, acrylonitrile butadiene styrene (ABS), acrylic, poly-carbonate, or any other suitable material for use in medical devices. It is further consistent with the present invention to monitor CO 2 , respiratory rate, respiratory volume, respiratory effort and other patient parameters in the absence of nasal interface  40 , where monitoring may be intracorporeal or extracorporeal. The present invention further comprises tubing (not shown) associated with the ports of nasal interface  40 , where the tubing may connect nasal interface  40  to a plurality of sensors, gas delivery systems, and/or other suitable peripherals. The tubing may be constructed out of nylon, polyvinyl, silicon, or other suitable materials commonly known in the art.  
         [0031]    [0031]FIG. 4 illustrates one embodiment of ear mount  54  of visual display  31  (FIG. 2). LEDs may be mounted on ear mount  54  which may be adapted for placement on the ear or ears of patient  18 . Ear mount  54  comprises stalk  50 , base  51 , support  52 , first interfacing surface  53 , and second interfacing surface  55 . First interfacing surface  53  may be partially or completely covered in a cushioning surface (not shown), where the cushioning surface is the surface that will come into direct contact with the ear of patient  18 . The cushioning surface may be constructed from foam, padded vinyl, or any other material suitable for providing patient comfort. In one embodiment of the present invention, second interfacing surface  55  interfaces with LED display  60  (described below with respect to FIG. 7).  
         [0032]    Stalk  50  may be detachably connectable to clasp  57  of support band  58  or permanently affixed to clasp  57  (described below with respect to FIG. 5). Clasp  57  may be a snap fit clasp or any other suitable clasp commonly known in the art. Stalk  50  may be adjustable and/or flexible and/or malleable to provide optimal patient comfort. Ear mount  54  may be constructed from ABS, polycarbonate, or any other suitable material commonly known in the art.  
         [0033]    [0033]FIG. 5 illustrates one embodiment of support band  59 , which comprises support member  58 , clasp  57 , and comfort band connector  56 . Support band  59  may be designed to be detachably removable from ear mount  54  (FIG. 4). Support band  59  may be a head band, where support band  59  is designed to fit snugly around the head of patient  18 . Support band  59  may be constructed from any suitable material commonly known in the art, however flexible materials such as, for example, poly-carbonate, silicon, or nylon are preferable. Positioning support band  59 , ear mount  54 , and LED display  60  (FIG. 7) in the cranial region of patient  18  provides user  13  with a display of high visibility. Support band  59  may be designed to carry a plurality of ear mounts  54  placed on each ear of patient  18 . Due to the significant number of procedures requiring patients to lie on their sides, the present invention comprises mounting ear mount  54  over one or both ears. Placing LED display  60  in the cranial region of patient  18  allows user  13  to visually monitor LED display  60  and the respiratory parameters of patient  18  visible to the naked eye simultaneously. The present invention further comprises adapting support band  59  to fit any portion of the body of patient  18 , adapting support band  59  for placement on existing medical equipment such as, for example, bed rails, and/or adapting support band  59  to fit on user  13 , such as, for example, in the form of a bracelet.  
         [0034]    LED display  60  may be utilized in the absence of ear mount  54  and/or support band  59 , where LED display  60  is positioned at any suitable location on the body of patient  18 , at any suitable location in the operating room, or at any suitable location on the body of user  13 . LED display  60  may be integrated with a bracelet, an adhesive for attachment to existing medical structures, or placed in a remote location for remote monitoring. One embodiment of LED display  60  is further disclosed in FIG. 7.  
         [0035]    [0035]FIG. 6 illustrates one embodiment of a method for pressure waveform analysis and segmentation in accordance with the present invention. Pressure waveform  75  comprises positive pressure region  76 , negative pressure region  77 , and zero pressure axis  78 . FIG. 6 illustrates one full tidal breath of patient  18 , where positive pressure region  76  correlates with exhalation and negative pressure region  77  correlates with inhalation. Pressure waveform  75  is at, or close to, the zero pressure axis  78  during the transition from exhalation to inhalation and inhalation to exhalation.  
         [0036]    The present invention comprises establishing a series of predetermined positive pressure thresholds  79 ,  80 ,  81 ,  82 ,  83 ,  84  and a series of predetermined negative pressure thresholds  85 ,  86 ,  87 ,  88 ,  89 ,  90 . As patient  18  inhales and exhales, controller  14  will ascertain which of the predetermined thresholds  79 ,  80 ,  81 ,  82 ,  83 ,  84 ,  85 ,  86 ,  87 ,  88 ,  89 ,  90  has been exceeded by the respiratory pressure waveform  75 . Information relative to magnitude of pressure change associated with inspiration and expiration will then be routed from controller  14  to LED display  60 , where specific LEDs associated with corresponding predetermined thresholds will illuminate. Exhalations and inhalations of a low magnitude will result in a minimal number of LEDs lighting, whereas exhalations and inhalations of a high magnitude will result in a greater number of LEDs lighting. By placing LED display  60  in a highly visible area, user  13  or other attending clinicians may visually monitor the respiratory condition of patient  18  in a semi-quantitative manner. Any suitable number of predetermined thresholds  79 ,  80 ,  81 ,  82 ,  83 ,  84 ,  85 ,  86 ,  87 ,  88 ,  89 ,  90  may be set at a plurality of pressure levels suitable for a particular patient  18  or application. The present invention further comprises associating positive pressure thresholds  79 ,  80 ,  81 ,  82 ,  83 ,  84  with LEDs  61 ,  62 ,  63 ,  64 ,  65 ,  66  (FIG. 7), where LEDs  61 ,  62 ,  63 ,  64 ,  65 ,  66  are of a particular color such as, for example, blue or gray. The present invention further comprises associating negative pressure thresholds  85 ,  86 ,  87 ,  88 ,  89 ,  90  where LEDs  68 ,  69 ,  70 ,  71 ,  72 ,  73  are of a particular color different from that associated with exhalation LEDs  67  such as, for example, green. Providing variable color for patient  18  inhalation and exhalation allows user  13  to ascertain at a glance whether patient  18  is inhaling or exhaling, and the pressure magnitude associated with the exhalation or inhalation.  
         [0037]    The present invention further comprises establishing alarm parameters within controller  14 , where if the inhalations or exhalations of patient  18  do not exceed predetermined pressure thresholds for a predetermined period of time, controller  14  may initiate an alarm condition. In the event of an alarm condition, controller  14  may be programmed to display evidence of the alarm or potentially dangerous patient episode via a series of LEDs  91 ,  92 ,  93  associated with LED display  60 . For example, first series of LEDs  91  may correlate to a warning condition, second series of LEDs  92  may correlate to a more significant warning condition, and third series of LEDs  93  may correlate to yet a more significant warning condition.  
         [0038]    [0038]FIG. 7 illustrates one embodiment of LED display  60  in accordance with the present invention comprising first exhalation LED  61 , second exhalation LED  62 , third exhalation LED  63 , fourth exhalation LED  64 , fifth exhalation LED  65 , and sixth exhalation LED  66 , collectively referred to as exhalation LEDs  67 . LED display  60  further comprises first inhalation LED  68 , second inhalation LED  69 , third inhalation LED  70 , fourth inhalation LED  71 , fifth inhalation LED  72 , and sixth inhalation LED  73 , collectively referred to as inhalation LEDs  74 . LED display  60  further comprises first series of LEDs  91 , second series of LEDs  92 , third series of LEDs  93 , and base  94 . In one embodiment of the present invention, base  94  is affixed to ear mount  54 , where LEDs associated with LED display  60  face away from patient  18 . However, it is contemplated that base  94  be constructed from flexible material or rigid material where base  94  may be placed in any suitable highly visible location.  
         [0039]    In one embodiment of the present invention, first exhalation LED  61  corresponds to positive pressure threshold  79 , where an exhalation that exceeds first positive pressure threshold  79  will result in first exhalation LED  61  lighting. Second exhalation LED  62  corresponds to second positive pressure threshold  80 , where an exhalation that exceeds second positive pressure threshold  80  will result in both first exhalation and second exhalation LEDs  61 ,  62  lighting. LEDs corresponding to predetermined thresholds will additively light in the above described fashion, where third exhalation LED  63  corresponds to third positive pressure threshold  81 , fourth exhalation LED  64  corresponds to fourth positive pressure threshold  82 , fifth exhalation LED  65  corresponds to fifth positive pressure threshold  83 , and sixth exhalation LED  66  corresponds to sixth positive pressure threshold  84 .  
         [0040]    The present invention further comprises providing inhalation LEDs  74  where first inhalation LED  68  corresponds to negative pressure threshold  85 , where an inhalation that exceeds first negative pressure threshold  85  will result in first inhalation LED  68  lighting. Second inhalation LED  69  corresponds to second negative pressure threshold  86 , where an inhalation that exceeds second negative pressure threshold  86  will result in both first inhalation and second inhalation LEDs  68 ,  69  lighting. LEDs corresponding to predetermined thresholds will additively light in the above described fashion, where third inhalation LED  70  corresponds to third negative pressure threshold  87 , fourth inhalation LED  71  corresponds to fourth negative pressure threshold  88 , fifth inhalation LED  72  corresponds to fifth negative pressure threshold  89 , and sixth inhalation LED  73  corresponds to sixth negative pressure threshold  90 .  
         [0041]    The thresholds  79 - 90  may be absolute or relative values. For example, for a pressure sensor where 0 output voltage represents zero or ambient pressure, each threshold may be fixed at a set voltage representing a given pressure level. With a bi-polar, linear pressure sensor where each inch of water pressure is 10 volts of output voltage and 0 V represents ambient (zero) pressure, a first threshold may be set at +0.1 V representing a pressure threshold of 0.01″ of water. However if the zero output voltage drifts on the pressure sensor (“zero drift”), the absolute voltage thresholds will no longer correspond to the desired pressure thresholds. Thus, a preferred embodiment uses relative pressure thresholds whereby the unique voltage corresponding to each threshold is re-adjusted to maintain the desired difference relative to the new output voltage at ambient pressure, in the event of zero drift. This method requires frequent zero calibration of the pressure sensor by exposing it intermittently and briefly to ambient pressure and recording the actual output voltage at zero or ambient pressure.  
         [0042]    LED display  60  further comprises first series of LEDs  91 , where first series of LEDs  91  may be associated with a first alarm condition; second series of LEDs  92 , where second series of LEDs  92  may be associated with a second alarm condition; and third series of LEDs  93 , where third series of LEDs  93  may be associated with a third alarm condition. First, second, and third series of LEDs  91 ,  92 ,  93  may employ any suitable number of LEDs such as, for example, four LEDs in each series, where the LEDs may be of any suitable color and may be programmed to blink, revolve, or indicate an alarm to user  13  by any other means commonly known in the art. The present invention further comprises employing one or a plurality of illumination devices in cooperation with or in place of LEDs associated with LED display  60  such as, for example, lamps or liquid crystal displays (LCDs). The LEDs associated with the present invention may be configured in a plurality of ways in accordance with the present invention such as, for example, a circular or sinusoidal pattern. Any suitable number of LEDs with corresponding pressure thresholds may be established in accordance with the present invention. Though sensor  32  is a pressure sensor in one embodiment of the present invention, it is contemplated that sensor  32  may be any suitable sensor such as, for example, a temperature sensor, where a waveform may be established corresponding to that sensor, where predetermined thresholds may be established based on the particular characteristics and unique properties of different sensors. It is further contemplated that exhalation LEDs  67  and/or inhalation LEDs  74  grow brighter as the magnitude of exhalation and/or inhalation pressure increases. In one embodiment of the present invention, the increased brightness is accomplished by pulse width modulation of the current or voltage waveform supplied to the LEDs associated with visual display  31 .  
         [0043]    Providing highly visible LEDs corresponding to the respiratory condition of patient  18  provides user  13  with easily viewable, semi-quantitative respiratory information. The present invention allows user  13  to quickly ascertain at a glance whether patient  18  is inhaling or exhaling, at what rate patient  18  is inhaling and exhaling, and the magnitude of inhalation and exhalation. LEDs associated with a critical patient episode may also be present, alerting attending clinicians in a highly visible manner of a potential problem. Integrating drug delivery  19  with respiratory monitoring  11  provides for the immediate deactivation or stepping down of drug delivery rate in the event of a negative patient episode, whereas it may have taken a while for a clinician to diagnose and respond to the alarm. The series  67  and  74  of LEDs (FIG. 7) provide a quantized visual indicator of the respiratory effect (pressure swings at the airway). In general, a respiratory monitor of effect (the result of a breath such as pressure swings at the airway or exhaled humidity) is more reliable than a monitor of respiratory effort (such as a transthoracic impedance plethysmography) because the latter is fooled when there is an effort but no effect such as in the case of a blocked airway.  
         [0044]    [0044]FIG. 8 illustrates one embodiment of method  100  for implementing respiratory monitoring  11  in accordance with the present invention. Method  100  comprises step  101  of attaching the patient interface, comprising fitting patient  18  with visual display  31  and nasal cannula  30 . Visual display  31  may be placed at any suitable position on patient  18 , on the user, in the operating room, or in a remote location. Nasal cannula  30  may be an integrated oxygen delivery and patient monitoring system, or may be any other suitable means of monitoring the respiratory condition of patient  18 . Once visual display  31  and nasal cannula  30  have been properly fitted, method  100  transitions to step  102  of monitoring the patient.  
         [0045]    Step  102  of monitoring the patient comprises, in one embodiment of the present invention, integrating respiratory monitoring  11  with patient interface  17 , where pressure variations caused by respiration pass from nasal cannula  30  to sensor  32 . Step  102  of monitoring the patient may further comprise a plurality of sensors  32 , such as thermistors, flow meters, humidity sensors, and/or other sensors commonly known in the art, in cooperation with, or in the absence of a pressure sensor. Signals related to respiratory pressure associated with inhalation and exhalation of patient  18  may be routed to controller  14 , where controller  14  is programmed to evaluate the data, output data related to respiratory condition and determine if a negative patient episode has occurred. Alarm conditions associated with respiratory monitoring  11  will be further discussed herein.  
         [0046]    Following step  102  of monitoring the patient, method  100  proceeds to query whether pressure evaluated by sensor  32  is a negative pressure or positive pressure, herein referred to as query  103 . Negative or sub-ambient pressure is associated with inhalation, whereas positive or supra-ambient pressure is associated with exhalation. Controller  14  comprises programming designed to interpret the signals from sensor  32  as corresponding to either positive or negative pressure. If controller  14  determines that patient  18  is generating negative pressure corresponding to an inhalation, method  100  transitions to query  104  to determine whether the negative pressure exceeds negative pressure threshold  85 .  
         [0047]    Query  104  comprises controller  14  evaluating signals from sensor  32  to determine if the negative pressure exceeds the predetermined threshold. The predetermined threshold may be set at any pressure suitable for patient  18  or the application at hand. If the negative pressure of inhalation of patient  18  does not exceed negative pressure threshold  85 , no LEDs will light on visual display  31 , and method  100  will transition to step  102  of monitoring the patient. In further embodiments of the present invention, as will be discussed herein, failing to exceed the predetermined thresholds may result in one or a plurality of alarm responses.  
         [0048]    If the negative pressure of the inhalation exceeds negative pressure threshold  85 , method  100  proceeds to step  105  of lighting the first negative pressure LED  68 . Following step  105  of lighting the first negative pressure LED, method  100  proceeds to query whether the negative pressure associated with the inhalation of patient  18  exceeds the second negative pressure threshold, herein referred to as query  106 .  
         [0049]    Query  106  comprises programming controller  14  with a second predetermined negative pressure threshold such as, for example, negative pressure threshold  86 . Controller  14  will then interpret signals from sensor  32  to determine if the negative pressure associated with exhalation exceeds the negative pressure threshold  86 . If the negative pressure does not exceed negative pressure threshold  86 , method  100  returns to step  102  of monitoring the patient.  
         [0050]    If the negative pressure exceeds negative pressure threshold  86 , method  100  proceeds to step  107  of lighting the second negative pressure LED  69 . In one embodiment of the present invention, negative pressure of sufficient magnitude to cross negative pressure threshold  86  results in both first inhalation LED  68  and second inhalation LED  69  being illuminated simultaneously. A further embodiment of the present invention comprises pulse width modulation (PWM) of the electrical supply delivered to an LED array. As a greater number of predetermined thresholds are crossed, the pulse width is increased resulting in brighter light intensity of the LEDs. For example, second inhalation LED  69  may have a longer pulse width than first inhalation LED  68 , resulting in second inhalation LED  69  having a brighter appearance than first inhalation LED  68 . Providing LEDs and multiple pulse width modulations may result in highly visually discernable levels of patient respiration.  
         [0051]    Following step  107  of lighting the second pressure LED, method  100  proceeds to query whether the negative pressure associated with patient inhalation exceeds negative pressure threshold  87 , herein referred to as query  108 . If the negative pressure does not exceed negative pressure threshold  87 , method  100  returns to step  102  of monitoring the patient. If the negative pressure exceeds negative pressure threshold  87 , method  100  proceeds to step  109  of lighting the third negative pressure LED  70 .  
         [0052]    Following step  109  of lighting the third pressure LED  70 , method  100  proceeds to query whether the negative pressure associated with inhalation exceeds negative pressure threshold  88 , herein referred to as query  110 . If the negative pressure does not exceed negative pressure threshold  88 , method  100  returns to step  102  of monitoring the patient. If the negative pressure exceeds negative pressure threshold  88 , method  100  proceeds to step  111  of lighting the fourth negative pressure LED  71 .  
         [0053]    Following step  111  of lighting the fourth negative pressure LED  71 , method  100  proceeds to query whether the negative pressure associated with inhalation exceeds negative pressure threshold  89 , herein referred to as query  112 . If the negative pressure does not exceed negative pressure threshold  89 , method  100  returns to step  102  of monitoring the patient. If the negative pressure exceeds negative pressure threshold  89 , method  100  proceeds to step  113  of lighting the fifth negative pressure LED  72 .  
         [0054]    Following step  113  of lighting the fifth pressure LED  72 , method  100  proceeds to query whether the negative pressure associated with inhalation exceeds negative pressure threshold  90 , herein referred to as query  114 . If the negative pressure does not exceed negative pressure threshold  90 , method  100  returns to step  102  of monitoring the patient. If the negative pressure exceeds negative pressure threshold  90 , method  100  proceeds to step  115  of lighting the sixth negative pressure LED  73 .  
         [0055]    The present invention further comprises lighting up all LEDs associated with crossed negative pressure thresholds simultaneously where, for example, if the sixth negative LED  73  is on, all of the LEDs associated with lesser negative thresholds are also illuminated.  
         [0056]    Returning to query  103 , if controller  14  determines patient  18  is generating positive or supra-ambient pressure corresponding to an exhalation, method  100  transitions to query  116  to determine whether the positive pressure exceeds positive pressure threshold  79 .  
         [0057]    Query  116  comprises controller  14  evaluating signals from sensor  32  to determine if the positive pressure exceeds predetermined threshold  79 . The predetermined threshold may be set at any pressure suitable for patient  18  or the application at hand. If the positive pressure of exhalation of patient  18  does not exceed positive pressure threshold  79 , no LEDs will light on visual display  31 , and method  100  will continue with step  102  of monitoring the patient. In further embodiments of the present invention, as will be discussed herein, failing to exceed the predetermined thresholds may result in one or a plurality of alarm responses.  
         [0058]    If the positive pressure of the exhalation of patient  18  exceeds positive pressure threshold  79 , method  100  proceeds to step  117  of lighting the first positive pressure LED  61 . Following step  117  of lighting the first positive pressure LED, method  100  proceeds to query whether the positive pressure associated with exhalation exceeds the second positive pressure threshold  80 , herein referred to as query  118 .  
         [0059]    Query  118  comprises controller  14  interpreting signals from sensor  32  to determine if the positive pressure associated with exhalation exceeds the positive pressure threshold  80 . If the positive pressure does not exceed positive pressure threshold  80 , method  100  returns to step  102  of monitoring the patient.  
         [0060]    If the positive pressure exceeds positive pressure threshold  80 , method  100  proceeds to step  119  of lighting the second positive pressure LED  62 . In one embodiment of the present invention, positive pressure of sufficient magnitude to cross positive pressure threshold  80  results in both first exhalation LED  61  and second exhalation LED  62  being illuminated simultaneously. A further embodiment of the present invention comprises pulse width modulations (PWM) of the electrical supply to an LED array. As a greater number of predetermined thresholds are crossed, the pulse width is increased, resulting in an increase in the light intensity of the LEDs. For example, second exhalation LED  62  may have a longer pulse width than first exhalation LED  61 , resulting in second exhalation LED  62  having a brighter appearance than first exhalation LED  61 . Providing LEDs and multiple pulse width modulations may result in highly visually discernable levels of respiration.  
         [0061]    Following step  119  of lighting the second pressure LED  62 , method  100  proceeds to query whether the positive pressure associated with exhalation exceeds positive pressure threshold  81 , herein referred to as query  120 . If the positive pressure does not exceed positive pressure threshold  81 , method  100  returns to step  102  of monitoring the patient. If the positive pressure exceeds positive pressure threshold  81 , method  100  proceeds to step  121  of lighting the third positive pressure LED  63 .  
         [0062]    Following step  121  of lighting the third positive pressure LED  63 , method  100  proceeds to query whether the positive pressure associated with exhalation exceeds positive pressure threshold  82 , herein referred to as query  122 . If the positive pressure does not exceed positive pressure threshold  82 , method  100  returns to step  102  of monitoring the patient. If the positive pressure exceeds positive pressure threshold  82 , method  100  proceeds to step  123  of lighting the fourth positive pressure LED  64 .  
         [0063]    Following step  123  of lighting the fourth positive pressure LED  64 , method  100  proceeds to query whether the positive pressure associated with exhalation exceeds positive pressure threshold  83 , herein referred to as query  124 . If the positive pressure does not exceed positive pressure threshold  83 , method  100  returns to step  102  of monitoring the patient. If the positive pressure exceeds positive pressure threshold  83 , method  100  proceeds to step  125  of lighting the fifth positive pressure LED  65 .  
         [0064]    Following step  125  of lighting the fifth positive pressure LED  65 , method  100  proceeds to query whether the positive pressure associated with exhalation exceeds positive pressure threshold  84 , herein referred to as query  126 . If the positive pressure does not exceed positive pressure threshold  84 , method  100  returns to step  102  of monitoring the patient. If the positive pressure exceeds positive pressure threshold  84 , method  100  proceeds to step  127  of lighting the sixth positive pressure LED  66 .  
         [0065]    The present invention further comprises lighting up all LEDs associated with crossed positive pressure thresholds simultaneously where, for example, if the LED  66  is on, all of the LEDs associated with lesser positive thresholds are also illuminated.  
         [0066]    [0066]FIG. 9 illustrates one embodiment of method  199  for employing respiratory monitoring  11  having alarm responses. Step  200  of establishing first alarm parameters, comprises establishing predetermined parameters such as, for example, minimum pressure thresholds, that are programmed into controller  14 . The predetermined parameters associated with step  200  comprise early warning parameters, where if a parameter or threshold is not met, it would indicate to user  13  that patient  18  needs to be carefully watched. Step  201  of establishing second alarm parameters, comprises establishing predetermined parameters associated with a moderately critical patient state. For example, thresholds established in step  201  may indicate a more critical patient situation than those established in step  200 . Step  202  of establishing third alarm parameters comprises establishing predetermined parameters associated with a severely critical patient state. For example, thresholds established in step  202  may indicate a more critical patient situation than those established in step  201  or  200 . It is in accordance with the present invention that a plurality of alarm responses be incorporated into method  199 , where thresholds are established by evaluating any suitable patient parameter such as, for example, respiratory rate or respiratory pressure.  
         [0067]    Method  199  further comprises step  203  of attaching the patient interface, consistent with step  101  (FIG. 8), and step  204  of monitoring the patient, consistent with step  102  (FIG. 8). While patient  18  is being monitored, method  199  queries whether data received by controller  14  is outside the established first alarm parameters, herein referred to as query  205 . If the signals received by controller  14  fall inside the parameters established in step  200 , method  199  will not activate first alarm condition  206  and will continue step  204  of monitoring the patient. If the signals received by controller  14  fall outside the parameters established in step  200 , method  199  will proceed to step  206  of generating a first alarm condition.  
         [0068]    The first alarm condition in step  206  comprises initiating a visual alarm via first series of LEDs  91  (FIG. 7) to user  13 . The first alarm condition in step  206  may cause first series of LEDs  91  to flash repeatedly, revolve, or alert user  13  in any other suitable manner. In one embodiment of the present invention, first series of LEDs  91  is a color, e.g., white, distinguishable from inhalation LEDs  74 , exhalation LEDs  67 , second series of LEDs  92 , and third series of LEDs  93 . First alarm condition in step  206  may further initiate an auditory signal or alarm. In the event that respiratory monitoring  11  is integrated with drug delivery  19 , as may be the case in sedation and analgesia systems or anesthesia delivery systems, the first alarm condition in step  206  may optionally initiate a step down or total deactivation of drug delivery rate associated with drug delivery  19 .  
         [0069]    The first alarm condition may generate a silent but visible alarm such as the white LED series lighting up to indicate that the anthropomorphic alarm algorithm has gone into a “hypervigilant” or attention mode. The alarm is silent so that it does not distract the user and because the conditions triggering the alarm are not serious enough to warrant distracting the user. However, to make sure that data is not being masked from the user, the white LEDs in series  91  light up as silent indicators. The first alarm condition may be triggered by the partial pressure of CO 2  averaged over e.g., 12 seconds, dropping below a threshold. In some instances, the first alarm condition may also be accompanied by a drug pause where administration of drugs is temporarily halted, especially if potent drugs are being administered.  
         [0070]    Following the first alarm condition in step  206 , method  199  will proceed to query whether data received by controller  14  is outside the parameters established in step  201 , herein referred to as query  207 . If the signals received by controller  14  fall within the parameters established in step  201 , method  199  will return to query  205 . If the signals received by controller  14  fall outside the parameters established in step  201 , method  199  will proceed to the second alarm condition in step  208 .  
         [0071]    The second alarm condition in step  208  comprises, in one embodiment of the present invention, initiating a visual alarm via second series of LEDs  92  (FIG. 7) to user  13 . The second alarm condition in step  208  may cause second series of LEDs  92  to flash repeatedly, revolve, or alert user  13  in any other suitable manner. In one embodiment of the present invention, second series of LEDs  92  is a color, e.g., orange, distinguishable from inhalation LEDs  74 , exhalation LEDs  67 , first series of LEDs  91 , and third series of LEDs  93 . The second alarm condition in step  208  may further initiate an auditory signal or alarm. In the event that respiratory monitoring  11  is integrated with drug delivery  19 , as may be the case in sedation and analgesia systems and anesthesia delivery systems, the second alarm condition in step  208  may initiate a step down or total deactivation of drug delivery rate associated with drug delivery  19 .  
         [0072]    The second alarm condition may be synchronized with the messages displayed on the main user interface of a sedation and analgesia or anesthesia delivery system. Thus the orange LEDs in series  92  would light up in synchrony with an orange caution alarm on the main user interface of the sedation and analgesia system. A second alarm condition may be caused for example by a low respiratory rate.  
         [0073]    Following the second alarm condition in step  208 , method  199  will proceed to query whether data received by controller  14  is outside the parameters established in step  202 , herein referred to as query  209 . If the signals received by controller  14  fall within the parameters established in step  202 , method  199  will return to query  207 . If the signals received by controller  14  fall outside the parameters established in step  202 , method  199  will proceed to the third alarm condition in step  210 .  
         [0074]    The third alarm condition in step  210  comprises, in one embodiment of the present invention, initiating a visual alarm via third series of LEDs  93  (FIG. 7) to user  13 . The third alarm condition in step  210  may cause third series of LEDs  93  to flash repeatedly, revolve, or alert user  13  in any other suitable manner. In one embodiment of the present invention, third series of LEDs  93  is a color, e.g., red, distinguishable from inhalation LEDs  74 , exhalation LEDs  67 , first series of LEDs  91 , and second series of LEDs  92 . The third alarm condition in step  210  may further initiate an auditory signal or alarm. In the event that respiratory monitoring  11  is integrated with drug delivery  19 , as may be the case in sedation and analgesia systems or anesthesia delivery systems, the third alarm condition in step  210  may initiate a step down or total deactivation of drug delivery rate associated with drug delivery  19 . The third alarm condition may light the red LEDs in series  93  in synchrony with a red warning alarm on the main user interface of the sedation and analgesia system.  
         [0075]    The present invention further comprises any suitable number of alarms or alarm condition steps, alerting user  13  in any suitable manner of a negative patient episode detected by controller  14 , alarm condition steps that deactivate a plurality of critical patient peripherals such as, for example, a blood pressure cuff, reflective coverings positionable over ear mount  54 , where light emitted from LEDs is magnified, and the use of method  100  in cooperation with method  199 , and the use of respiratory monitoring  11  in the presence or absence of integrated oxygen delivery, analgesic delivery, and/or patient monitoring.  
         [0076]    While exemplary embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous insubstantial variations, changes, and substitutions will now be apparent to those skilled in the art without departing from the scope of the invention disclosed herein by the Applicants. Accordingly, it is intended that the invention be limited only by the spirit and scope of the claims as they will be allowed.

Technology Classification (CPC): 0