Patent Application
20230358629
This invention relates to a door opening tracking system and method and, more particularly, to a system and method that utilizes at least one pressure sensor for automatically detecting and counting door openings in a predetermined area, such as an operating room of a hospital.
Understanding factors that lead to compromised air quality in hospital settings and improving surgical safety is an ongoing challenge of high importance. Operating room air quality is a major factor that can contribute to surgical site infections (SSI). A variety of risk factors affect the contamination level of the air in an operating room including types of medical procedures performed, occupancy levels and foot traffic. A number of controls have been designed and are being improved upon to help operating rooms maintain clean air including filtered air changes, laminar air flow, UV germicidal lamps, portable negative pressure units containing HEPA and carbon filters, and monitoring systems. Building design considerations also play a role including placing the operating theatre in an area that is progressively less contaminated relative to the reception area.
Additionally, operating rooms are typically under positive pressure as a preventive measure to inhibit the entrance of contaminants from less sterile areas to more sterile areas. An operating room under positive pressure has a higher barometric pressure than adjacent rooms and corridors, resulting in outward air flow from the operating room to the surrounding areas. Door opening events have been shown to affect the airflow patterns in the operating room setting. Door openings have been correlated with increased levels of contamination including increased numbers of colony forming units. A number of studies have assessed the number of door opening events that occur during surgery and have expressed concern with the high frequency of door opening events. Furthering our understanding of the effects of door opening on the operating room environment and exploring practical ways to monitor its occurrence will facilitate the implementation of enhanced safety practices in surgical environments and management of operating rooms.
A clinical study has shown that the total time that a door remains open during surgery affects the minimum room pressure recorded during the surgery, although pressure readings immediately before, after and during the exact time of door openings are unknown. One issue with this study is that pressure readings vary naturally throughout the day and minimum values can be a consequence of natural changes in pressure rather than door openings. Additionally, taking one minimum value per surgical procedure does not allow for the counting of door openings based on pressure changes. Devices can be attached to doors to detect openings; however, these methods can be difficult to implement and are subject to malfunction given that they are attached to or very near a large moving object.
What is needed, therefore, is a system and method that passively and automatically detects door openings and analyzes barometric pressure to facilitate reducing contamination and surgical site infections.
A passive and automatic system and method are shown that automatically detects and counts door openings. The system and method described herein involve analyzing barometric pressure data collected from a single pressure sensor stationed inside an enclosed room. In the preferred embodiment, a single pressure sensor placed in the corner of an operating room can signal door opening/closing events through detection of rapid reduction and recovery of barometric pressure. Predetermined mathematical methods and systems are applied to the data to rapidly transform the data and automatically detect and count door openings. Barometric pressure values are collected preferably each second, allowing for rapid and abrupt changes to be captured and reported.
In one embodiment, the sensor need not be placed at the door to capture the pressure drop nor does it require more than one device to process pressure differences between adjacent rooms, allowing for a high degree of ease in sensor integration into the operating room environment. Automated electronic capture and recording is applied to track door opening events. In another embodiment, the system and method quantitatively examines the pattern of pressure drop and rise each time an operating room door is opened and closed. As is known, barometric pressure fluctuates naturally throughout the day, and another embodiment of the systems and methods described herein distinguish pressure changes induced by door opening events from background changes in pressure. The loss of positive pressure upon opening an operating room door has important implications for air quality in operating rooms. Loss of positive pressure combined with the presence of a large air exchange zone (the open doorway) creates a path for contaminants to enter the room. The systems and methods described herein utilize an algorithm and an equation that facilitates identification of pressure changes associated with door opening and automatically counts the door openings. A single equation can be applied to a set of barometric pressure data to rapidly count door openings. The systems and methods described herein contribute to a wider effort of identifying, understanding and reducing adverse events in operating rooms in pursuit of improving surgical standards and enhancing patient safety.
Certain rooms in hospitals are slightly pressurized to prevent influx of contaminants when doors are opened. It is desired to know how often and how long such doors are opened, in order to assess the contamination which results. An object of the invention is to provide a non-contact detector for detecting and counting door-opening events and the duration of those events.
One object of the invention is to provide a passive method for automatically detecting and counting door opening events.
Another object of the invention is to passively and automatically detect and count door opening events using at least one sensor.
Still another object of the invention is to provide a passive system and method for automatically detecting and counting door opening events utilizing a single pressure sensor.
Yet another object of the invention is to provide a passive system and method for automatically detecting and counting door opening events utilizing at least one sensor that is not coupled to and/or is remote from the door.
Still another object of the invention is to provide a system and method that automatically and electronically captures, records and tracks door opening events and examines a pattern of pressure drops and rises associated with such events.
Another object of the invention is to provide a system and method that quantitatively examines a pattern of pressure drops and rises each time a door, for example a door in an operating room, opens or closes.
Yet another object of the invention is to provide a system and method that includes and utilizes a predetermined equation that facilitates identification of pressure changes associated with the door openings and closings and automatically counts the door openings and performs a response thereto.
Still another object of the invention is to provide a single equation that can be applied to a set of barometric pressure data to rapidly count a door opening event pressure data sensed from at least one sensor.
Another object of the invention is to provide a system and method that utilizes a single pressure sensor to generate pressure data and to determine a door opening event in response thereto.
Yet another object of the invention is to provide a system and method that utilizes a single pressure sensor that is situated remote from a door in a room, such as an operating room, and that utilizes an equation to distinguish pressure changes induced by door opening events from background changes in pressure unrelated to door opening events.
Another object of the invention is to provide an improved system and method for sensing door opening events and for taking action, such as increasing a pressure in the room, in response thereto in order to improve surgical standards, enhance patient and operating personnel safety and the like by facilitating reducing airborne contamination in the room.
In one form of the invention, a pressure sensor produces a record, which contains a sequence of measurements of barometric pressure in a pressurized room. An opening door produces a characteristic, though small, sequence of pressure pulses. The invention looks for the characteristic sequence in the data or record and when the sequence is found, the invention declares and identifies that a door has opened.
In one aspect, one embodiment of the invention comprises a method of detecting opening of a portal in a pressurized room, comprising measuring a sequence of barometric pressures at a fixed location within the room; and based solely upon pressures within the sequence, identifying a sub-sequence during which the portal had opened.
In another aspect, another embodiment of the invention comprises a method of detecting opening of a portal in a pressurized room, comprising generating a history of barometric pressures at a fixed location within the room; and using the history and no other data, ascertaining whether the portal had opened.
In yet another aspect, another embodiment of the invention comprises a method, comprising obtaining data on barometric pressure within a room over a span of time; ascertaining whether sections of the data meet predetermined criteria; and if so, issuing a signal indicating that a portal in the room has opened during the span of time.
In still another aspect, another embodiment of the invention comprises a system for a pressurized room in which (A) barometric pressure varies daily between a maximum Pmax and a minimum Pmin, and (B) opening a portal in the room causes a pressure disturbance Pd which is less than 10 percent of (Pmax - Pmin), comprising a recording system for producing a record of the barometric pressure within the room over a span of time, and an analyzing system for detecting a pressure pattern indicative of an open portal in a wall of the room and, in response, issuing a portal-open signal.
In another aspect, another embodiment of the invention comprises a method to track door openings comprising using a barometric pressure sensor; performing electronic data collection of pressure readings as a function of time; processing and analyzing the data to ascertain door opening events; applying an equation to transform the data to facilitate identification of door opening events; and applying a program to automatically count a number of door openings based on the transformed data.
In another aspect, another embodiment of the invention comprises a method for measuring changes in barometric pressure at a predetermined location after a door opens, the method comprising the steps of measuring barometric pressure at the location at different times, and if measured barometric pressures meet predetermined criteria, generating a signal indicating that the door has opened.
In another aspect, another embodiment of the invention comprises an apparatus for a room having a portal which opens and closes, comprising within the room, a non-moving pressure sensor at a fixed location, which produces a history of barometric pressure in the room, the history containing (1) an early interval, (2) a middle interval, and (3) a late interval; a processor which derives a figure-of-merit for each interval and, based on the figures-of-merit, concludes whether the portal has opened during one of the intervals.
In another aspect, another embodiment of the invention comprises a method of detecting opening of a portal in a pressurized room, comprising generating a history of barometric pressures at a fixed location within the room; identifying midpoint T11 of the history; deriving an indicator IN1 of amount of scatter of pressures occurring before the midpoint; deriving an indicator IN2 of amount of scatter of pressures occurring after the midpoint; computing pressure drop A immediately preceding T11; computing pressure drop D immediately following T11; computing a pressure drop B based on A and B; based on A, B, D, IN1, IN2, and a correction factor, issuing a signal indicating that the portal has been opened.
In another aspect, another embodiment of the invention comprises a method of detecting opening of a portal in a pressurized room, comprising obtaining a sequence of barometric pressure for a normally closed room; defining (1) early, (2) middle, and (3) late periods in the sequence; deducing amount of scatter in pressures of both the early and late periods; deducing trending in pressure in the middle period; and based on deductions of paragraphs (b) and (c), issuing a signal indicating that a portal to the room had opened while the sequence was taken.
In another aspect, another embodiment of the invention comprises a method of analyzing a sequence of barometric pressure data taken from a normally closed room, comprising dividing the sequence into (1) early, (2) middle, and (3) late periods; ascertaining early scatter in the early period, and late scatter in the late period; ascertaining a trend in the middle period; based on (i) early scatter, (ii) late scatter, and (iii) inflection weight, issuing a signal indicating that a portal to the room had opened while the sequence was being generated.
In another aspect, another embodiment of the invention comprises a method of detecting opening of a portal in a pressurized room, comprising obtaining a sequence of 21 pressure measurements, N1 through N21, each at a respective time T1 through T21, and all measured within the room at a fixed location remote from the portal; computing pressure drop A between times T10 and T11; computing pressure drop B between times T10 and T12; computing pressure drop D between times T11 and T12; computing standard deviation C of ten pressures T1 through T10; computing standard deviation E of ten pressures T12 through T21; computing SUM = A + B - C -D + E - 0.105; and if SUM is positive, issuing a signal indicating that the portal has been opened between T1 and T10.
In another aspect, another embodiment of the invention comprises a door opening tracking system for positive pressure rooms comprising a continuous barometric pressure sensor; an electronic data processing system comprising a noise reduction means; calculation of a temporally based data packet comprising a moving pressure data baseline and a discrete pressure event or spike, a spike threshold determination, and a data storage and retrieval means.
In another aspect, another embodiment of the invention comprises a method for identification of door openings in a positive pressure operating room comprising pressure sensing creating a continuous data stream; creating at least one data packet consisting of a set of pressure values over a predetermined period of time; entering the data packet into the data memory of a date processing device; and electronic reporting of the door openings.
This invention, including all embodiments shown and described herein, could be used alone or together and/or in combination with one or more of the features covered by one or more of the following list of features:
These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
In one embodiment, the barometric pressure sensor 16 is a micro electromechanical system (MEMs) based barometric pressure sensor. The barometric pressure sensor 16 comprises a sensor that detects atmospheric pressure that may use different sensing approaches, such as a piezo-resistive sensing approach, capacitance sensing approach, deposition sensing approach, a wire, a mechanical or other equivalent means to generate an electrical signal on a continuous basis that responds to the pressure changes in the room 18. In this case the wire and mechanical means were mechanisms of electrical signal transport or creation. For example, a piezo device can produce electricity upon undergoing mechanical deformation. As far as detection methods go, the sensor used in one embodiment is a MEMs sensor.
The barometric pressure sensor 16 is not in contact with either the door 14 or the door frame 14a but is remote from both. In one form of the invention, the barometric pressure sensor 16 is located in the maximum possible distance from the door 14, while still remaining within the room 18. In another form of the invention, the barometric pressure sensor 16 is located at least half that maximal distance from the door 14.
A schematic block 20 in
As mentioned, the barometric pressure sensor 16 does not have to be located at or near the door 14, but rather can be in the periphery of the room 18. The computation system and apparatus 20 is situated in the room 18 and may be incorporated on or into an air cleaning and disinfection device 30 or may be located remotely on a remote server 32. In that embodiment, the barometric pressure sensor 16 and/or the air cleaning and disinfection device 30 in the room 18 may comprise conventional wireless communication technology (not shown) that permits transmission to the remote server 32 in a manner that is conventionally known.
As alluded to earlier, it should be understood that an algorithm or equation 36 may be resident in the barometric pressure sensor 16 or stored in memory or storage 20b of the computation system and apparatus 20 so that the barometric pressure sensor 16 outputs sensed data directly thereto for processing. The algorithm or equation 36 is described in detail later herein and generally automatically counts door 14 opening events and then the number of output events which indicate door opening events derived in equation 36 described later herein. Alternatively, and in another embodiment, the barometric pressure sensor 16, the application of the algorithm or equation 36 and the computation system and apparatus 20 are situated in either the air cleaning and disinfection device 30 or a remote server 32.
The barometric pressure sensor 16 takes a sequence of pressure readings, such as that illustrated in
In a preferred embodiment, the system, method and apparatus 10 examines the sequence of pressure data and these are processed as described herein in order to ascertain patterns or sequences which indicate when the door 14 in
Initially, at time zero, the pressure P1 is above external ambient pressure in region 12 of
The plot in
In region 26, the door 14 is fully open and remains fully open for some period of time for illustration. It should be understood that the period may be short, as when the door 14 was opened by a person entering the room 18, who then immediately releases the door 14 or allows it to close after the person fully enters or exits the room 18 or door frame 14a. On the other hand, the period may be long, such as when two people enter or exit the room 18 through the door frame 14a with a gurney, bed or equivalent.
The data shows that the pressure drop is fast, but the pressure restores quickly. Thereafter, the door 14 closes in region 28. The pressure initially continues to decrease at the same rate as at the end of region 26 because the door 14 opening or aperture is the same at points 31 and 32 in the plot. Note that pressure drop or airflow rate decreases because the door 14 is closing, which interrupts or decreases airflow out of or into the room 18 so that the pressure becomes constant in region 30 after closure completes. The pressure P33 in region 30 is lower than pressure P1 because of the loss of air from the room 18. As the heating ventilation air conditioning (HVAC) or other means forces air into the room 18, the pressure will rise back to the predetermined level at P1. In theory, a pressure wave (not shown) can occur at the moment of complete closure of the door 14 because the complete closure causes an instantaneous deceleration of the air flowing through the door frame 14a, analogous to water hammer which occurs in a plumbing system when a water valve is closed. A similar comment applies to a possible pressure wave at the initial moment of opening.
As mentioned, there may be an agency pressurizing the room 18, such as an HVAC blower (not shown), which may attempt to restore pressure to the predetermined initial pressure P1. Alternatively, the agency may have been called into service at some point during the events of
The correspondence between the terms of the equation and the twenty-one (n1 - n21) illustrative pressures is indicated by the dashed arrows. It is to be noted that more or fewer pressure pairs or variable combinations, such as the variables (n10 -n11), (n1, ... n10), may be used. Some pressures, such as n10, appear more than once in equation 36, but a dashed arrow is drawn for only one appearance and ease of illustration. The Greek lower case sigma (σ indicates a standard deviation). That is, the expression “σ(n1 ... n10)” means “standard deviation of pressures n1 through n10”. For ease of understanding and type-setting, the expression “σ(n1 ... n10)” will be written “SIGMA(n1 ... n10)” in this description.
Referring back to the example in
It should be understood that the data generated by the barometric pressure sensor 16 is analyzed for a first predetermined amount of time before and a second predetermined amount of time after a specific time parameter in order to identity whether or not a door 14 opening event occurred within the timeframe of the time parameter. For example, the first and second predetermined amounts of time may be a few seconds or several seconds before and after or in one embodiment, it could be ten seconds before and/or ten seconds after the specific time parameter. The specific time parameter is the time in which a door 14 induced change in pressure is detected. In the equation and routine provided, it lasts for two seconds, but could be longer or shorter. It represents the time during the calculated difference between the pressure when the door 14 is closed and when it is open. Although the specific time parameter is two seconds, it could be longer or shorter, and it may change in response to various conditions, such as door size and type, door closing time, room pressure and the like, it is best to use the first two seconds.
Thereafter, the mean is subtracted from each pressure, as indicated in box or area 42, and each average or mean result is squared, as indicated in box 44. All squared values in block 44 are added together to produce 325.6 value as shown at the right side of
As mentioned earlier herein, the barometric pressure sensor 16 does not have to be located near the door 14 or, for example, activated or tripped by the door 14 opening. The barometric pressure sensor 16 does not have to be located on/or adjacent to or on the door 14, but rather can be located remote from it. In one embodiment, the barometric pressure sensor 16 is located in the room 18 and coupled to the computation system and apparatus 20 which is described in more detail later herein. Alternatively, it should be understood that the barometric pressure sensor 16 is situated in the air cleaning and disinfection device 30 which is situated in the room 18. The air cleaning and disinfection device 30 may be the ILLUVIA® system available from Aerobiotix, LLC located in Miamisburg, Ohio. The air cleaning and disinfection device 30 may be portable and moved to different areas of the room 18. It should also be understood that the computation system and apparatus 20 may also be separately located in the room 18, such as with the barometric pressure sensor 16, or be in or on the air cleaning and disinfection device 30. Alternatively, and as shown in
In one embodiment of the invention, the sensor 16 is a barometric sensor, such as LPS33W MEMS pressure sensor available from STMicroelectronics located in Geneva, Switzerland.
The computation system and apparatus 20 comprises a processor 20a and the memory or storage 20b. It should be understood that the algorithm or equation 36 may also be independent from the computation system and apparatus 20. It can be calculated using the collected data anywhere the data is located. It can be used manually via a spreadsheet on any computer, when the data is stored in a cloud database, sch as memory or storage 20b, it can be used there or it can be resident on the computation system and apparatus 20 and used there.
As described earlier herein, the barometric pressure sensor 16 senses the barometric pressure and data associated with that sensed event is stored in the computation system and apparatus 20 in the memory or storage 20b of the processor 20a. The algorithm represented by the equation 36 as shown in
The system, method and apparatus 10 generates a report for appropriate personnel, such as the operating room manager, to assess and determine if improvements or changes need to be made regarding door 14 operation, door 14 openings, room pressure and the like. Also, the information can be used to understand likely causes of surgical site infections.
Advantageously, the system, method and apparatus 10 provides and defines a tool to help understand the dynamics, safety and functionality of the operating room and where there is room for improvement. At a minimum, customers may be provided with regular reports comprising a variety of data including the number of door 14 openings based on the system, method and apparatus 10 described herein.
Several internal experiments were performed consisting of twenty (20) door 14 openings with the associated data shown in
The air cleaning and disinfection device 30 contains many sensors, one of which is the MEMS barometric pressure sensor 16. The air cleaning and disinfection device 30 collects data from all the sensors, and the system, method and apparatus 10 generates a Microsoft Excel® file of the data. It should be understood that the system, method and apparatus 10 may transfer the data to a remote server 32 or to the air cleaning and disinfection device 30 computation system and apparatus 20 and memory or storage 20b thereof for processing by computation system and apparatus 20.
The application of the algorithm and characteristics of the equation 36 will now be described.
As shown earlier, equation 36 is as follows and is represented in several of the figures.
Referring back to
On the other hand, if the bracketed term is positive, then that is taken or interpreted to indicate that a door 14 opening has occurred at some time between T1 and T10. It is noted that the door 14 opening, which is inferred by equation 36, occurred at a time in the past and is inferred based on the historical record of pressures shown in
In contrast, the pressure differentials A, B, and D (
The term labeled A, namely (n10 - n11), can be called the pressure drop preceding the midpoint T11.
The term labeled D, namely (n11 - n12), can be called the pressure drop succeeding the midpoint T11.
The term labeled B, namely (n10 - n12), can be called the pressure drop spanning the midpoint T11. It is the pressure drop between the times T10 and T12, which span T11.
The pressure drops labeled A and B are positive or have positive signs in equation 36 and are added to the other terms within the brackets. However, the pressure drop labeled D has a negative sign. That is, the pressure drop succeeding the midpoint T11 and labeled D tends to counter-act the pressure drop preceding the midpoint T11 and labeled A, as to their influences on the bracketed term in equation 36. It should be understood that pressure drop labeled D corrects for false positives.
Terms C and E are standard deviations. Term C can be called SIGMA(EARLY) because it is the standard deviation of the early pressures, namely, those occurring before time T11. Term E can be called SIGMA(LATE) because it is the standard deviation of the late pressures, namely, those occurring after time T11.
Standard deviation is one of many measures of the scatter of data.
The standard deviations in equation 36 in
FIRST. If the early pressures are widely scattered with a small mean, then SIGMA(EARLY) will be large, analogous to SD20 in
SECOND. If as in FIRST, the early pressures are widely scattered with a small mean, then SIGMA(EARLY) will be large, analogous to SD20 in
THIRD (OPPOSITE OF SECOND). If the early pressures are narrowly scattered with a large mean, then SIGMA(EARLY) will be small, analogous to SD5 in
Term F is a correction factor, which can be determined empirically. For example, the door 14 can be repeatedly closed, perhaps by a robot arm or automatic opener (not shown). Equation 36 is solved for each closure event, but with a different correction factor F. Eventually, a factor F will be found where the bracketed term in equation 36 goes positive. That factor is then used. The correction factor is determined by measuring known door 14 openings events and determining the value needed to generate a positive value that can be used to signify a door 14 opening without creating false positives. The same equation is used for all events. The correct correction factor is the smallest value that gives the highest percent accuracy. The inventors have found that in controlled settings 100% accuracy can be obtained. The inventors envision that the correction factor might change in different environments. Currently, the only way this could be done is by either collecting data from known openings or possibly by carefully analyzing field data, however, it is not always clear if a door 14 was opened when the data is messy, so collecting data from controlled settings is preferred in one illustrative embodiment.
For ease of understanding the embodiment, system and method being described, the operation of the systems and methods will be described relative to several examples and illustrations. This discussion will consider examples of progressively more complex pressure distributions of the type shown in
A primary aspect of equation 36 is as follows:
FIRST. If the bracketed quantity (that is the algebraic sum of terms A, B, C, D, E, and F) is negative, thus causing the square root to be imaginary, then it is concluded that door 14 in
SECOND. If the bracketed quantity is positive, thus causing the square root to be real, it is concluded that the door 14 in
THIRD. It is considered highly unlikely that the bracketed quantity will equal zero, so that case is not considered or can be considered indeterminate.
The following examples will facilitate understanding the embodiment being described.
Terms A, B, and D concern pressures n10, n11, and n12, which are all equal. Therefore, terms A, B, and D are zero.
Term C, the standard deviation for the ten pressures n1 - n10, and also called SIGMA(EARLY), is also zero: all pressures are the same. Term E, which is the standard deviation for the ten pressures n11 - n21 and also called SIGMA(LATE), is also zero because all pressures are the same.
The bracketed term in equation 36 will be negative 0.105, as indicated. It should be understood that the last term in one embodiment is 0.105, but this could vary and be selected based upon the environment. The term could vary between 0.1 and 0.12. It should be understood that the term and range can be different, such as 0.05 to 0.15, and it can possibly be broader. If an unusually high positive pressure is detected, then a larger adjustment might be required. Preferably, an experiment may be performed at several different positive pressures to determine if there may be a trend. It should be understood that the last term is computed based upon the specific parameters of the room 18 which can include, and are not limited to, the size of the room, a predetermined positive pressure in the room, the number of doors or windows in the room, ventilation level in the room and the like. These parameters all weigh into the computation of the last term. The square root of a negative number is imaginary. When the bracketed term is negative and an imaginary number is produced by equation 36, one form of the invention interprets that as indicating that door 14 has not opened during the period spanning from T1 to T10.
The constant pressure of
Term C, the standard deviation for the ten pressure readings taken from T1 through T10, has some value, indicated by arrow A1 in the bottom left part of
In
If the standard deviations for both pressure waves are the same, as indicated, then terms C and E cancel each other. Equation 36 takes the square root of negative 0.105 and produces an imaginary number. The invention declares that the door 14 remained closed between times T1 and T10.
Same facts as in EXAMPLE 3, but as shown in
The bracketed term becomes [-SIGMA(EARLY) + SIGMA(LATE) - 0.105]. This bracketed term is necessarily negative because, by stipulation, SIGMA(EARLY) is greater than SIGMA(LATE) and SIGMA(EARLY) is given a negative sign. Further, SIGMA(EARLY) is made further negative by the addition of negative 0.105 to it.
One embodiment of the invention declares that the door 14 remained closed between times T1 and T10.
Same facts as in Example 4, except that SIGMA(LATE) is now greater than SIGMA(EARLY) as illustrated in
A simplified explanation of the physics underlying the situation can be given in connection with
A mathematical fact is shown in
In
In general, if bell-wave BB is a narrow pressure pulse in time (i.e., SIGMA(EARLY) is “small”), followed by a shallow, wide pressure pulse BC (i.e., SIGMA(LATE) is “large”), then subtracting both [SIGMA(EARLY) and 0.105] from SIGMA(LATE) can produce a positive number. In this instance, one embodiment of the invention would declare that door 14 opened between times T1 and T10.
In
The value within the parentheses of term A will equal the value within the parentheses of term D (because both equal DELTAP), but term A will be negative (because n11 is greater than n10) and term D is assigned a negative sign.
So, the expression within brackets can be re-written as expression G, which is illustrated underneath the equation x(t) at the top of
If SD(EARLY) equals SD(LATE), then terms L and N in expression J in
However, if SD(LATE) is sufficiently large (i.e., the pressure distribution at times T12 - T21 is “short” and “wide,”) then term N in expression J can dominate, making the expression positive and result in a declaration of opening the door 14.
It should be understood that the term N is detected and recorded every second in one embodiment using the following equation to analyze a series of sequentially recorded data:
where nt is the barometric pressure at time, t, σ is the standard deviation of the specified range and x is a real number or an imaginary number (square root of a negative number) and indicates whether or not a door 14 opening event has occurred or has likely occurred within the time range of t to t + 1 s, and up to a range of t to t + 10 s. When x is a positive number, a door 14 opening event has occurred. When x is an imaginary number a door 14 opening did not occur or very likely did not occur. This equation could also be written as x(t) = √[(J - K) + (J - L) - σ(A ...J) - (K - L) + σ(L ... U) - 0.105] where A... U are the barometric pressure values at time t.
In one embodiment, the door 14 opening events are counted and based upon the output derived from the equation 36 including counting the number of data points in a data set where the outputs are greater than zero as derived from the equation.
In one embodiment, the number of data points in a data set where outputs are values greater than zero are derived and a value indicating a door 14 opening event.
If DELTAP is a negative blip, as in
On the other hand, if the negative blip (that is, DELTAP) is large, a door 14 opening will be declared.
The decision on whether to declare a door 14 opening will depend on the algebraic sign of expression H. If SIGMA(LATE) dominates, making the expression H positive, then the door 14 is declared to have opened.
The left side of each
In
In
In
The preceding discussion has considered processing of the data of the type shown in
During operation, the window of data values, which is labeled W1 in
Next, the window is shifted or moved to W3 in
Next, the window is shifted or moved to W4 in
Next, the window is shifted or moved to W5 in
Thus, it should be appreciated that the data processor 20a utilizes the equation 36 from memory or storage 20b and is adapted to apply it on a moving temporal baseline or moving frame substantially illustrated in
It should be understood that the system, method and apparatus 10 and processor 20a may provide amplification of the deviation events and/or data packets. The data is amplified by transformation into a positive spike. All values around the spike are zero if a door 14 is not opened. There may be other ways to amplify the data, such as squaring it, although this probably isn’t necessary. It should be understood that the computation system and apparatus 20 and processor 20a causes the data associated with the processed deviation events to be transformed into discrete data points representing door 14 openings. The equation 36 transforms the raw data into either errors or positive numbers. The Microsoft Excel® “COUNTIF” function then counts the number of instances of a positive number. When graphed, the deviations are transformed into spikes (see
In this manner, successive groups of 21 pressure measurements may be processed. Alternatively, the equation 36 may be elongated to consider more or fewer data points as desired. In short, the embodiments may be adapted to consider more or fewer data points.
1. Each term A, B and D in
2. It may not be necessary to compute term D in
3. It is to be understood that one embodiment of the invention eliminates any need for calibration based on variations on outdoor atmospheric pressure. For example,
Restated as a numerical example, the pressure pulse indicating the door 14 opening may be 10 percent of the swing from P50 to P60. Given that fact, the swing from P50 to P60 will be detected incorrectly as the pressure pulse caused by a door 14 opening. In contrast, the embodiments of the invention base its decisions solely on the pressure data recorded between T1 and T21.
4. A pressure sequence detected by barometric pressure sensor 16 (
Other signatures will be obtained for different events, such as a pair of nurses wheeling a gurney through the door 14 in order to enter the hospital operating room.
5. In one form of the invention, the sequence of pressures n1 through n21 in
6. Advantageously, the system, process and method described herein provide means and apparatus for transforming barometric pressure data into an output 62 that counts door 14 opening events. A report is generated that tells personnel, such as a doctor or the operating room manager, the number of door 14 openings within a surgical period. The operating room manager may then use the information to determine if improvement is needed regarding the number of times a door 14 is opened during surgery. The reports may include number of door 14 openings, CO2 level, particle counts, VOC level, etc. The number of door 14 openings is one factor that can contribute to increased surgical site infection using the reports and data can reduce contamination in the room 18, thereby resulting in decreased levels of patient infections.
7. In one embodiment, the system 10 isolates relatively large pressure changes deduced by door 14 openings and natural variations in barometric pressure so that door 14 opening events can be distinguished. The door 14 opening is determined by the large discrete changes in pressure. The large pressure changes are isolated from natural variations by analyzing the standard deviation as is done in equation 36. The inventors have currently not found a way to do a simple subtraction pressure at time T2 minus pressure at time T1. If there might be some situations where excessively high positive pressure is sensed for example, where a more simplified equation can be used such as simply subtracting data point two from data point 1. Equation 36 and the process or system 10 is designed to isolate large pressure changes from natural variations
8. It should be understood that the system, process and method 10 described herein may be applied to any enclosed space under positive pressure, not just the operating room 18. It could be another room in the medical facility or in a room in a non-medical facility. In short, it could be applied to any enclosed space having a door.
9. Advantageously, the system, process and method 10 transform pressure data, especially a set of pressure loss data associated with a door 14 opening event into a single point associated with that event. “Single point” means a spike (see
10. Advantageously, the system, process and method can record pressure data every second for a period of time, such as ten seconds, which could be longer or shorter if desired. Also, more or fewer pressure data readings may be taken.
11. The computation system and apparatus 20 may comprise a curve-flattening and/or noise reduction means or algorithm to remove variations from normal environmental and atmospheric changes in barometric pressure to provide a “de-noising” means or apparatus that may be applied to the data. This may be in the form of a filtration, averaging, wave transforming, de-noising algorithms or similar processes. This could be taking the derivative, the square root, the moving average, or the like. There are a variety of mathematical functions that someone skilled in the art might use. One thing that may be done with the data is averaging each point.
12. As mentioned earlier, once the door 14 openings are identified in the manner described herein, the packet associated with that door 14 opening is stored in memory 20b of the computation system and apparatus 20 which is either resident on the air cleaning and disinfection device 30 or on a remote server 32, for example, so that reporting and alarm can be associated with such door 14 opening. In this regard, either the remote server 32 or the air cleaning and disinfection device 30 may comprise an electronic reporting and alarm 34 which may be used to automatically or manually perform an action, such as turning on a blower of a HVAC unit to increase the pressure in the room 18. Primarily, one goal of these embodiments is to collect and report the data and use it to detect door 14 openings. Other activities could be performed by the system 10, such as energizing an alarm 34 or increasing the HVAC pressure in the room 18. It may not be practical in an operating room to increase the positive pressure because once the door 14 is open it may take a seemingly excessive amount of positive pressure to maintain positive pressure. In a preferred embodiment, the goal is to generate daily reports and track door 14 openings over time. This might help uncover surgical site infection risk factors. For example, it would be advantageous to know when calculated door 14 openings are above a certain threshold, the chance of surgical site infection increases significantly.
It should be appreciated that the system, method and apparatus 10 may also be used to determine deviations within sets of an upstream and/or downstream distant sets, creating a blended value of deviation s, via averaging via mean, median, mode, range or similar means. Using this method means using average values for the standard deviation that is determined by studying variations in barometric pressure with the door 14 closed and never opened. The analysis could also involve calculating the standard deviation every 10 seconds (or possibly some other amount of time). The standard deviations would then be averaged. The median and mode could also be calculated. It would then need to be determined through controlled experiments whether or not this approach is more useful than calculating the standard deviation as the frame moves in equation 36.
It should be understood that numerous substitutions and modifications can be undertaken without departing from the true spirit and scope of the present invention. What is desired to be secured by Letters Patent is the invention as defined in the following claims.
Advantageously, another embodiment of this invention, including all embodiments shown and described herein, could be used alone or together and/or in combination with one or more of the features covered by one or more of the claims set forth herein, including but not limited to one or more of the features or steps mentioned in the Summary of the Invention and the claims.
While the system, apparatus and method herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise system, apparatus and method, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.
The present application claims priority to provisional U.S. Application Serial No. 63/337,809 filed May 3, 2022, to which Applicant claims the benefit of the filing date of this provisional application, which is incorporated herein by reference and made a part hereof.
| Number | Date | Country | |
|---|---|---|---|
| 63337809 | May 2022 | US |
