Patient monitoring alarm escalation system and method

[0001] This application is a continuation of U.S. application Ser. No. 11/241,513 filed Sep. 30, 2005, the disclosure of which is hereby incorporated by reference in its entirety.

[0002] 1. Field of the Invention

[0003] The present invention relates generally to alarm systems for patient physiological data monitoring instruments. In particular, the present invention relates to an alarm escalation system including mechanisms for indicating a level of criticality of alarms corresponding to physiological measurements and equipment status indicators of patient monitoring devices.

[0004] 2. Description of the Related Art

[0005] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0006] Patient monitors include medical devices that facilitate observation of patient physiological data. For example, a typical patient monitor detects and displays a patient's vital signs continually. This improves patient care by facilitating continuous supervision of a patient without continuous attendance by a human observer (e.g., a nurse or physician). Typically, patient monitors include alarm systems that provide audible and/or visual indications of certain predefined conditions. For example, some patient monitors include alarms that are triggered based on physiological conditions (e.g., high and low patient heart rate thresholds, arterial oxyhemoglobin saturation) or status indicators for the monitor itself (e.g., power loss). These alarms further facilitate supervision of patients and improve patient care by providing caregivers with warnings concerning certain monitored conditions. Generally, such alarms remain in an alarm state until acknowledged by a user. For example, an audible alarm for a patient's abnormal systolic condition may continue to sound until a user presses an acknowledge button that silences the alarm and indicates that the alarm has been recognized. Such audible alarms for patient monitors generally incorporate unchanging alarm tones or auditory effects. It is now recognized that such unchanging alarms tend to cause patient monitor users/operators (e.g., nurses, physicians, and caregivers) to become desensitized to ongoing and unacknowledged audible alarms.

[0012] One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0013] FIG. 1 is a perspective view of a patient monitor in accordance with an exemplary embodiment of the present invention. Specifically, the patient monitor illustrated by FIG. 1 is a multi-speaker pulse oximeter 10 having a first speaker 12 and a second speaker 14. The pulse oximeter 10 may be configured to provide an active audible alarm with at least two distinctive tones. These distinctive tones may be utilized to elevate annoyance when an alarm condition remains unacknowledged for a certain period of time, thus directing a user's attention to the unacknowledged alarm condition. For example, in one embodiment, a first tone from the first speaker 12 is sounded in response to an alarm condition, and a second tone from the second speaker 14 is sounded as a reminder tone. The reminder tone is sounded after the alarm condition has remained unacknowledged for a designated amount of time. In another embodiment, distinctive reminder tones are sounded alternatively from the respective speakers 12 and 14, thus creating increasing audio agitation (e.g., increasing volume, frequency, and/or dissonance) after a designated amount of time has passed without the alarm condition having been acknowledged by pressing an alarm silence button 16. Additionally, the elevation of audio agitation may be accelerated the longer an alarm remains unacknowledged. For example, after the audio agitation has been increased a first time, the amount of time until it is increased again may be reduced by half and so forth.

[0014] In some embodiments, spatial separation of the first speaker 12 and the second speaker 14 may be used to increase alarm awareness among caregivers and to ensure that all areas of a room are accessible to an alarm. For example, stereo characteristics and so forth may be utilized to get the attention of a caregiver that is desensitized to typical alarms. In a specific example, the spatial separation of the first speaker 12 and second speaker 14 may be used to create unique sounds and/or to improve sound projection to all areas of a room. Further, embodiments of the present invention may be engineered to ensure that the location of the alarm device emitting the alarm is apparent to the caregiver. For example, if multiple devices are in a room, certain sound effects may be utilized to direct a caregiver's attention to the specific device that is emitting an alarm.

[0015] Alarm conditions are designated on the pulse oximeter 10 using set points or by designating patterns of values (e.g., patterns in an SpO2 trend) that can be entered via adjustment buttons 18. For example, a user can input a certain set point (e.g., 103 degrees Fahrenheit, blood oxygen level of 97%) that creates an alarm condition when crossed by actual patient data (e.g., actual patient temperature, actual blood oxygen level), or when processed values or patterns of values are detected. The pulse oximeter 10 may detect alarm conditions using an alarm detection device that compares designated set points with actual patient data received from a sensor 20 via a cable connection port 22 that is configured to communicatively couple with the sensor 20. For example, in some embodiments, the alarm detection device employs SatSeconds™ by Nellcor™ to detect alarms and manage nuisance alarms. SatSeconds™ may include alarming based on an integral of time and depth of a desaturation event. The sensor 20 may be defined as an accessory used to collect and send patient data to the pulse oximeter 10. One end of the sensor 20 is typically coupled to a patient (e.g., to a patient's finger, toe, ear lobe, or forehead) and the other end couples either directly or indirectly (e.g., via a separate monitor cable) to the pulse oximeter 10. Exemplary sensors may include sensors available from Nellcor Puritan Bennett Incorporated. The sensor 20 in the illustrated embodiment couples with a patient's finger and is configured to collect patient physiological data by sensing a patient's pulse rate and percentage of oxygen in the arterial blood. Once collected, these measurements are sent to the pulse oximeter 10.

[0016] As set forth above, the pulse oximeter 10 illustrated by FIG. 1 includes dual speakers 12 and 14. The speakers 12 and 14 are configured to provide audible alarms based on certain detected conditions. For example, the speakers 12 and 14 may be utilized to produce audible alarms for detected conditions including: low battery, high or low oxygen saturation, high or low pulse rate, sensor disconnect, high patient temperature, high or low blood pressure, and so forth. While the embodiment illustrated by FIG. 1 includes a pair of speakers 12 and 14, other embodiments may include a single speaker, more than two speakers, or options relating to the provision of one or more speakers. Indeed, some embodiments include a monitor having connection points adapted to communicatively couple with a plurality of speakers. For example, a monitor in accordance with present embodiments may include one or more built-in speakers, expansion ports for coupling to one or more speakers, or both. Further, in some embodiments, remote speakers (e.g., pagers) may be utilized either with or without having speakers directly coupled to the pulse oximeter 10. It should be noted that in some embodiments, to utilize the connection points, external speakers are communicatively linked with the connection points and software on the oximeter 10 is updated to provide additional related functions.

[0017] Incorporating a plurality of speakers (e.g., speaker 12 and 14) with the pulse oximeter 10 provides versatility, redundancy, and reliability. For example, by emitting alarm tones and alarm reminder tones from multiple speakers, embodiments of the present invention can produce unique and recognizable alarm sounds that attract the attention of users by elevating annoyance levels of the alarm sounds. This versatility can increase the awareness of caregivers that may not respond quickly to standard alarms, resulting in improved response times and so forth. In a specific example, an alarm may sound from speaker 12 based on a blood pressure reading that passes a predefined alarm threshold. If this alarm is not acknowledged by, for example, pressing the alarm silence button 16, speaker 14 emits a secondary alarm having a different tone than the first alarm to further alert the caregiver of the alarm condition.

[0018] In addition to providing auditory versatility, having multiple speakers creates redundancy that improves reliability in the event of a speaker failure (e.g., a speaker being blocked and muffled by an object or a speaker with a faulty connection). Not all unacknowledged alarms will necessarily result from caregivers failing to hear or recognize the initial alarm. Indeed, an initial alarm may remain unacknowledged because a speaker assigned the task of emitting the initial alarm either failed to produce or failed to adequately emit the initial alarm tone. For example, if speaker 12 is configured to emit an initial alarm tone and speaker 14 is configured to emit a reminder alarm tone after the initial alarm is unacknowledged for a designated period, the reminder alarm tone provided by speaker 14 will serve as a back up alarm to alert the user of a pending alarm condition in the event speaker 12 fails to provide the initial alarm tone.

[0019] In another embodiment, both speakers 12 and 14 are essentially completely redundant. For example, in a completely redundant embodiment, all speakers (e.g., 12 and 14) are configured to emit the same alarm tones and alarm reminder tones based on the same measured conditions and unacknowledged alarms. If one speaker fails, at least one other speaker will have been redundantly assigned the same alarming task.

[0020] It should be noted that, in some embodiments, alarms are visually and/or haptically indicated in addition to being audibly indicated. Indeed, alarms may be indicated to alert any of a caregiver's senses (e.g., sight, touch, and hearing). These alternative sensory indications (e.g., alarm lights and vibrating pagers) are additional tools with which a user's attention can be directed to an alarm condition. For example, the pulse oximeter 10 includes a display 24, such as a liquid crystal display (LCD), that visibly displays alarm indications and other information. In one embodiment, the display 24 is configured to visually communicate patient physiological data (e.g., oxygen saturation percentage, pulse amplitude, pulse rate) and alarms in the form of numeric data, textual data, and/or graphical data (e.g., plethysmographic waveforms and/or alarm icons). The display 24 may also be configured to display equipment status indicators such as an on/off indication depending on whether a power button 26 in latched or unlatched, a power indication depending on whether a power cord 28 is receiving power, and/or other equipment status indicators. In one embodiment, the display 24 is used to visually confirm values entered while configuring aspects of the pulse oximeter 10 (e.g., providing set points for alarms via the adjustment buttons 18). It should also be noted that these extra indications provide supplemental redundancy.

[0021] FIG. 2 is a block diagram of a method 40 for providing patient monitor alarms in accordance with an exemplary embodiment of the present invention. The method 40 can be implemented with a single alarm indicator or multiple alarm indicators. For example, embodiments of the present invention may use speakers, pagers, visual indicators, and/or haptic devices to provide the referenced signals (e.g., audible tones). The method 40 begins at block 42 and proceeds to block 44, which is a decision block regarding whether an alarm condition has been detected. If an alarm condition has not been detected, the method returns to the start (block 42). If an alarm condition has been detected, an alarm signal is emitted by one or multiple alarm indicators (e.g., speaker 12) in block 46 and an alarm timer is initiated in block 48. The alarm signal may include a tone emitted from a speaker, a vibration emitted from a pager, a light emitted from a display and so forth.

[0022] After an alarm has been initiated (block 46), the method 40 begins determining whether the alarm condition still exists and/or whether the alarm signal has been acknowledged, as illustrated by blocks 50 and 52. Specifically, block 50 is a decision block regarding whether a user has provided confirmation that the alarm condition has been recognized or acknowledged. Such an indication of acknowledgement may be provided by, for example, depressing the alarm silence button 16. If the alarm condition has been acknowledged, the unexpired alarm timer is reset or canceled (block 54) and an alarm silence timer may be initiated (block 56). In the illustrated embodiment, the alarm silence timer is then monitored, as illustrated by block 58. When the alarm silence timer expires, block 58 directs the method 40 to start again at block 42. In some embodiments, the alarm silence timer is not utilized. For example, in some embodiments, once a specific alarm is acknowledged, the same alarm condition will not initiate the primary alarm again, thus eliminating potentially unnecessary alarms. In other words, in such embodiments, the same alarm condition will not cause repeated alarm signals to be periodically emitted after acknowledgement when the alarm silence timer expires.

[0023] Block 52 is a decision block regarding whether the alarm condition still exists after being initiated. If the alarm condition is no longer present (e.g., the patient's blood pressure returns to normal), the alarm signal is canceled in block 60, the alarm timer is reset or canceled in block 62, and the method 40 begins again at block 42. For example, in one embodiment, if a patient's temperature passes a set point and then returns to normal the alarm will cease regardless of whether the alarm has been acknowledged. If the alarm condition remains present and has not been acknowledged, the alarm signal is continually emitted, the alarm timer continues to run, and the method 40 proceeds to block 64. It should be noted that in some embodiments, the presence of the alarm condition is not required to maintain the alarm. In other words, the method 40 proceeds without determining whether the alarm condition persists (block 52). For example, in some embodiments, the alarm remains active until acknowledged regardless of whether the alarm condition ceases to exist. This may be desirable in situations that benefit from requiring a user to be made aware that an alarm event occurred.

[0024] Block 64 is a decision block regarding whether the alarm timer has expired. If the alarm timer has not expired, the method 40 loops back to block 50. If the alarm timer has expired, a secondary alarm signal is emitted (block 66). As discussed above, this secondary alarm not only serves to increase awareness but also provides redundancy. In one embodiment, the secondary alarm signal has properties different than the primary alarm. For example, where the primary alarm is an audible tone, the secondary alarm may be an audible tone that is emitted with a higher frequency and/or a higher volume. Additionally, if the alarm timer has expired, the alarm timer may be reset with different properties (block 68). For example, the alarm timer may be reset with a reduced period (e.g., half of the initial alarm timer period). In some embodiments, this procedure continues as each successive alarm timer expires, thus gradually increasing communicated urgency, distinguishing features (e.g., type of sound), and/or the annoyance level of the alarm. Further, it should be noted that in some embodiments, acknowledging the alarm by, for example, pushing the alarm silence button 16, acknowledges and silences all alarms (e.g., both primary and secondary alarms).

[0025] FIG. 3 is a pressure-time plot of a primary alarm signal and a secondary alarm signal in accordance with an exemplary embodiment of the present invention. While two signals are depicted in the illustrated embodiment, in some embodiments a plurality of signals may be utilized. Specifically, the plot 72 represents an audible signal or alarm emitted from the first speaker 12 as a primary alarm when an alarm condition is detected and unacknowledged. The plot 74 represents an audible signal or alarm emitted from the second speaker 14 as a secondary alarm when the primary alarm has remained unacknowledged for a predetermined amount of time. In some embodiments, a single speaker can be used to emit both alarms 72 and 74. It should be noted that while the illustrated alarms 72 and 74 have pulse waveforms, in other embodiments, the alarms 72 and 74 can have different waveforms (e.g., ramp wave, sine wave, triangle wave). Further, in some embodiments, the alarm signals are not audible but include other types of signals (e.g., vibrations from a pager). For example, in one embodiment, alarm signals are provided by a single or redundant set of vibratory transducers to provide further safety, versatility, and reliability.

[0026] As shown in FIG. 3, the secondary alarm 74 is silent during the initial alarm period and changes in frequency over time to increase annoyance, thus drawing attention to the unacknowledged alarm condition. In the illustrated embodiment, after the primary alarm 72 remains unacknowledged for a first amount of time 76, the secondary alarm 74 is initiated with a duty cycle that is interleaved with that of the primary alarm 72. After a second amount of time 78 (e.g., half of the primary time) beyond initiation of the secondary alarm 74, properties of the secondary alarm 74 are changed. Specifically, in the illustrated embodiment, the frequency of the alarm is increased, thus increasing annoyance. In other embodiments, different aspects of the primary and/or secondary alarms 72 and 74 are changed. For example, amplitude, duty cycle, frequency, and harmonic content can be manipulated over time to increase annoyance levels of all or some signals being emitted. In one embodiment, the alarms 72 and 74 begin sweeping through frequencies as the alarm condition remains unacknowledged. In the illustrated embodiment, the annoyance level is continually increased until it reaches a peak level or the alarm is acknowledged. For example, after a third amount of time 80 (e.g., half of the second time 78) beyond the second amount of time 78, the frequency of the secondary alarm 74 is changed again.

[0027] FIG. 4 is a block diagram of a monitoring system in accordance with an exemplary embodiment of the present invention. Specifically, FIG. 4 illustrates a monitoring system 90 including a plurality of patient monitors 92 networked to a central management station 94 (e.g., a personal computer), which is coupled with an audible alarm system 96 and an alarm paging system 98. The alarm paging system 98 includes a set of wireless and mobile pagers 100. This monitoring system 90 facilitates monitoring multiple patients in, for example, a hospital or clinic. It should be noted that in some embodiments, the audible alarm system 96 and the alarm paging system 98 are included in the monitors 92. Further, it should be noted that in the illustrated embodiment, the monitoring system 90 is networked with network cables. However, in some embodiments, wireless communication is utilized.

[0028] Each of the patient monitors 92 includes a sensing device 102 (e.g., temperature sensor, pulse sensor) for measuring patient physiological data. Additionally, each of the monitors 92 or the central management station 94 is configured to alarm based on predefined physiological data values or conditions relating to such values. For example, an alarm may be activated when a patient's temperature has been at a certain level for a predefined amount of time.

[0029] When alarm conditions are detected, the system 90 emits alarm signals from the audible alarm system 96 and/or the alarm paging system 98. Further, as discussed above, if the alarm is not acknowledged, the monitoring system 90 increases the alarm annoyance level. For example, in the illustrated embodiment, a primary alarm signal is sent to a first pager 100A. If this primary alarm is not acknowledged within a predefined amount of time, a second alarm is sent to a second pager 100B. If the second alarm remains unacknowledged for a predefined amount of time (e.g., half of the time allotted to acknowledge the primary alarm), a third alarm is sent to a third pager 100C and so forth. Additionally, the annoyance level of each pager alarm may be increased. For example, the pagers may beep or vibrate with a higher amplitude and/or frequency. Further, audible alarms from a speaker or speakers of the audible alarm system 96 may substitute or supplement the pager alarms. Indeed, the audible alarm system 96 may emit audible alarm tones with increasingly annoying characteristics, as discussed above with regard to FIG. 3.

[0030] While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.