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Hospital Patient Safety

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Cell Phones? Smart Phones? Wi-Fi?

. . . or Response Paging?

Hospital patient safety demands effective clinical alarm notification. While cellular and Wi-Fi systems can serve this purpose, they lack the necessary performance and reliability to do it safely. Furthermore, notifications from cell phones and tablet computers create distractions and disrupt workflow. A third option, response paging, utilizes dedicated high-power transmitters to deliver alarm notifications quickly and reliably, confirming who receives each message, who reads it, and who will respond. Response paging notifies personnel without the uncertainty associated with cellular and Wi-Fi based systems, thereby improving patient safety and reducing risk.


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Modern hospitals use wireless technologies to send clinical alarm notifications directly to responding personnel. Such notification system must also includes delivery and read confirmation.

In a hospital, life-critical situations occur hundreds of times every day. They are detected by bedside monitors, clinical personnel, family members, and patients themselves, and the resulting clinical alarms are directed to appropriate personnel as they happen. The personnel receiving these alarm notifications are charged with taking appropriate responsive action to resolve each one.

Historically, clinical alarm notification has been the purview of dedicated, one-way paging systems. While these systems are simple, fast, and extremely reliable, they cannot confirm message receipt by personnel. This limitation creates an intelligence gap (and associated risk) in patient care, forcing hospitals to consider newer technologies with response capabilities.

In this respect, Cellular and 802.11 Wi-Fi based solutions are alluring alternatives to dedicated paging systems, as potential “single-device” solutions, with rich response capabilities. However, these systems are consumer-grade technologies with serious limitations insofar as mission critical communications. Wi-Fi systems have endemic problems with areas of poor signal, interference, and node congestion, and cellular systems rely on distant infrastructure which may become unavailable due to storms, connectivity problems, or commercial traffic congestion. In addition to the problems of availability and performance, Wi-Fi and cellular user equipment create notorious sources of personnel distraction and workflow disruption. In reality, these solutions can create more patient safety risks than the older paging systems they might replace.

A third option, response paging, provides fast and reliable alarm notification, combining the speed and reliability of traditional paging systems with state-of-the-art response notification capabilities. Response paging delivers the performance, reliability, and ease-of-use needed for mission critical applications such as clinical alarm notification, without the compromises seen in cellular and Wi-Fi systems.



Cellular-based solutions are susceptible to coverage problems, limited battery life, and distant infrastructure issues, all of which delay critical messages in unpredictable ways.

Mission-critical communication systems are often measured by their availability, or the probability that the system will be ready when it is needed. While cellular and Wi-Fi networks have reasonable availability for a commercial product, particularly when measured over long periods of time, they do not have the level of instantaneous reliability usually associated with mission-critical messages such as clinical alarm notifications.

Cellular System Availability

Cell phones depend on switching centers, base stations, and the public switched telephone network, as well as other local and regional network components. Smart phones have these same dependencies, and also require additional components such as the Apple App Store™, Push Notification Services, the Internet, and e-mail. One server crash can prevent smart phone apps from operating correctly, and natural or man-made disasters can bring down local, regional, or national cell phone services in unpredictable ways and for unpredictable amounts of time. Thus, a cellular-based hospital messaging system is inherently susceptible to local or distant problems beyond the hospital's ability to control or repair. This is true even if the system uses dedicated hospital base stations because the underlying control systems invariably reside in remote data centers many miles away from the hospital.

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A cellular-based hospital messaging system is inherently susceptible to local or distant problems beyond the hospital's ability to control or repair.

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  • In 2004 and 2005, several hurricanes and tropical storms caused repeated cell phone outages in Florida, some lasting 3 weeks or more and severely disrupting critical communications for dozens of police, fire, and EMS services. 1
  • In August 2005, Hurricane Katrina knocked out cell service to every person, hospital, and public safety agency within a several thousand square mile footprint, with outages lasting into the following year. 2
  • In August 2011, Hurricane Irene destroyed 130 cell towers and left another 215 towers without power, leaving 12,000 people and dozens of hospitals without cell phone service for several days in several states. 3
  • In August 2011, a minor earthquake a struck Northern Virginia, causing a spike in call volume and social media that knocked out AT&T, T-Mobile, and Verizon Wireless networks in several states for several hours. 4
  • In October 2011, a hardware failure in a RIM server facility brought down the entire Blackberry network in several countries for three days. 5
  • In June 2012, a fast-moving weather storm (derecho) brought down cellular systems in Ohio, Kentucky, Indiana, Pennsylvania, Virginia, and West Virginia, disconnecting 9-1-1 call centers for several days. 6
  • In October 2012, hurricane Sandy knocked out cellular networks in several states and disrupted cell phone communications far beyond storm-affected areas. 7

Wi-Fi System Availability

While Wi-Fi systems may not always depend on external elements for proper operation, they nonetheless depend on a myriad of internal components — hundreds to thousands of Access Points (AP's), routers, servers, and applications, plus associated configuration, power, physical wires and cables. Should any one of pieces become unavailable ( e.g., momentarily down for maintenance, down because of hardware problems, etc.), critical messages are not delivered until a technician is able to troubleshoot and resolve the underlying problem.

Additionally, Wi-Fi systems operate using unlicensed, unprotected radio channels, which are susceptible to disruption by smart phones, Bluetooth headsets, microwave ovens, fluorescent bulbs, and even faulty light switches or outlet boxes. For routine use, these problems usually amount to an annoyance. Personnel may occasionally have to reposition their device or step out into the hall to view pharmacy orders or patient history. However, when it comes to alarm notification, these same problems are far more serious. In these cases, responding personnel become inadvertently disconnected without any indication as to what is happening, and alarm notifications are missed entirely. This causes unpredictable increases in response delay, compromising patient safety and increasing risk across the hospital enterprise.


Wi-Fi networks are complex systems with many components. Wi-Fi based solutions are susceptible to coverage problems, IT issues, and limited battery life, all of which delay critical messages in unpredictable ways.

Cellular/Wi-Fi Handset Availability

User equipment with dead batteries cannot receive or display alarm notifications, and both cellular and Wi-Fi devices have a significant limitation in terms of battery life. These devices have an initial battery life of one to two days when used for clinical alarms, and this life rapidly drops quickly over time with the number of battery recharge cycles. Within 6 months, many batteries will die mid-shift and create significant workflow disruptions. Additionally, if personnel are not immediately aware that a battery has died, they may miss alarm notifications altogether until they realize their situation. In the interval before the problem is corrected, delayed alarms put patient safety at risk and alarm escalations compound alarm fatigue to the covering personnel.

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Wi-Fi systems are susceptible to disruption by smart phones, Bluetooth headsets, microwave ovens, fluorescent bulbs, and even faulty light switches or outlet boxes.

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Performance of an alarm notification system is the time required to deliver any given message. Although average performance of cellular and Wi-Fi based notification systems is reasonably fast, unpredictable delays introduce a great deal of variability from message to message. This unpredictability increases worst-case delivery time of asynchronous events, which in turn impacts alarm notification and response times.

Cellular Performance

All cellular messaging applications rely on the short messaging service (SMS), either to deliver the message directly or to deliver notification that a message data is pending. Cellular systems usually deliver SMS messages to a recipient's phone in just a few seconds, or complete a group message in a minute or so. However, cellular companies do not publish SMS performance standards, and these service levels are not predictable. Studies have shown that as many as 9% of SMS messages are delayed more than five minutes, with 5.1% never being delivered at all. 8 Additionally, SMS messages are routed through remote Mobile Switching Centers and SMS Centers, which routinely queue emergency codes behind social media updates and bulk advertising loads. This creates unpredictable delays during periods of distant network congestion.

Wi-Fi Performance

Wi-Fi systems offer more control and dedicated bandwidth to hospitals, but Wi-Fi also involves unpredictable messaging delays for other reasons. For mobile users, AP-to-AP handoff itself represents a service interruption. Under ideal conditions, actual hardware-level handoff is typically very quick, a tenth of a second or less. However end-user applications often suffer 5-10 seconds of total interruption, as noise (SNR) and packet errors begin to increase prior to the handoff event. A message sent to a user moving between areas of a unit can be delayed substantially while waiting for the handoff process to run its course. Additionally, large Wi-Fi systems (such as those required to cover a hospital campus) inherently suffer from a fundamental flaw in coverage. As a practical matter, Wi-Fi has only three available RF channels to share among all access points, which is simply not enough for a complex system. In a mid-size hospital, even the most careful planning, will create a certain number of inevitable dead spots. These spots can be caused by low signal or co-channel interference, and their effects have far-reaching consequences. Dead spots cause packet loss and retransmission, which cascades into wildly fluctuating performance for all users sharing the affected access point, even those in good coverage. 9


Low-power Wi-Fi systems create areas of weak signal, while higher-power Wi-Fi systems create areas of co-channel interference. Both issues delay or interrupt critical messages.


An effective notification system must not only alert personnel when necessary, but must accomplish this with minimal distraction and workflow disruption. While smart phones and tablet computers have made healthcare-related data far more available to clinical personnel whenever and wherever they want it, these devices also engage users with a high level of focus and interaction. When used to deliver asynchronous, notifications, these devices contribute significantly to user distraction and workflow disruption.

The journal Risk Management and Healthcare Policy recently published a risk assessment from several US hospitals, which determined that “findings from existing work illustrate that smart phones are a significant source of distraction for decision-based activities such as driving, classroom learning, and work-related tasks. Similarly, in health care work settings, these devices pose a great risk.” 10

Another study associated each interruption to medical care workflow with a 12.1% increase in procedural failures and a 12.7% increase in clinical errors 13 , with disruptions caused by phone messaging having contributing contributed to documented fatalities. 11

One such fatality “involved a resident and intern who discussed the plan of care for a patient while rounding. An attending told the resident to stop warfarin until an echocardiogram of the heart could be taken. While the resident began submitting the orders on her smartphone, she received an SMS text about an upcoming party. The resident chose to respond to the text. The order for the patient was never completed, and the patient continued to receive warfarin for three days.” 12

The effects of smart phone distractions go well beyond patient health risks. Studies have shown a general decline in professional relationships due to overuse of text messaging and a decrease in verbal communication. In a study of perfusionists it was “reported that 55.6% of 439 perfusionists admitted that they used a cellular phone, and 49.2% agreed that they had sent text messages while performing a cardiopulmonary bypass. Some 7.3% of the perfusionists admitted that the cellular phone had a negative impact on their performance. And 33.7% said they had seen another perfusionist distracted by the cellular phone. Of those surveyed, 21% reported having accessed e-mail, 15.1% having used the Internet, and 3.1% having used social networking sites.” 13

The very act of receiving a clinical alert on a smart phone or tablet computer is inherently a disruptive event. The user must recognize the alert, distinguish the alerting app from other applications on the device, access the app, and interact with the device to read and respond to the message. The level of distraction is so severe that one study recommends banning smart phones entirely from hospital ICUs and CCUs. 14

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"The level of distraction is so severe that one study recommends banning smart phones entirely from hospital ICUs and CCUs."

"Gill PS, Kamath A, Gill TS. Distraction: an assessment of smartphone usage in health care work settings. Risk Management and Healthcare Policy, August 27, 2012: 111"

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Response paging systems use two synchronized radio channels: a high-power channel to send messages, and a medium-power channel to receive confirmation and responses. One antenna provides reliable coverage to an entire hospital complex.

Response Paging, an evolution of traditional, one-way paging, uses a dedicated, high power RF transmitter, and adds a second return channel for confirmation and response. Both channels employ digital modulation, and they are synchronized together to optimize battery life and performance.

Response pagers include an embedded digital receiver and transmitter, along with a user-friendly interface and a variety of alerting and reply options. When a message arrives, the user can read it and reply with a single button press. If the user is already busy with critical care, he or she can escalate the message without removing the pager from the holster or taking time to view it. Also, pager batteries typically last 2-3 weeks, with periodic recharging by cable or dock.

Compared to other communications systems, response paging makes considerably less bandwidth available for data communications; however it also has several important advantages.

Response Paging Availability

Like traditional paging, response paging is extremely reliable, with a history of operation even during extraordinary catastrophes, when other communications systems fail outright. During the 9/11 terrorists attacks, paging systems continued operating even after serious infrastructure damage and peak congestion had rendered cellular networks useless. 15 During hurricane Katrina and its aftermath, response paging continued operating properly, despite extensive wind damage, power loss, and flooding had disabled virtually every other communication system and service in the region. 16

There are several reasons for this. First, unlike cellular and Wi-Fi systems, a response paging system is completely self-contained with minimal external dependency. An entire hospital system typically fits in a single equipment rack with no external requirement except for power.

Second, response paging systems send messages directly to personnel and receive their responses directly. Instead of multiple access points or base stations, a response paging system typically covers an entire hospital complex, plus several miles of surrounding terrain, using one high power antenna. It operates using dedicated, protected, FCC-licensed channels, and it suffers none of the issues related AP-to-AP hand-off, weak signal, or co-channel interference. Moreover, the simplicity of this type of system permits affordable redundancy on all levels, providing additional protection against unforeseen circumstance.

Response paging is designed from the ground up for critical messaging and mobile users. It eliminates the reliability compromises seen with com-parable cellular and Wi-Fi alerting systems, and delivers alarm notifications to responding personnel with certainty.

Response Paging Performance

A response paging system avoids the unpredictable performance of cellular and Wi-Fi systems by working in a fundamentally different way. First, it processes group messages natively using confirmed data broadcast, delivering critical messages to one recipient or hundreds of recipients within 5 seconds. Other communications technologies must break group messages into a series of individual messages, with delivery performance depending on group size.

Secondly, it uses high power transmitters to communicate directly with mobile personnel, without any intervening routers or switches. Other systems use multiple antennas, or expensive distributed antenna systems, often creating a complex variety of RF coverage issues.

Finally, a response paging system uses deterministic, prioritized scheduling to send critical messages immediately regardless of lower priority traffic. While the unpredictable performance of Wi-Fi and cellular systems create uncertainty, a response paging system delivers notifications immediately and without surprises.


With Confirmed Data Broadcast, a response paging system alerts a response group of any size within 5 seconds, then tracks who receives, reads, and replies to the message.

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Response paging uses one high power antenna for reliable, uniform coverage. Users receive notifications anywhere within the hospital, and simple user equipment displays messages without disrupting workflow or distracting the recipient.

Distractions and Workflow

In contrast to highly interactive smart phones or Wi-Fi devices, pagers represent an entirely different paradigm: an alerting appliance. They require no attention until they receive an alert, at which point they make the message instantly prominent and viewable with prompts for clear and simple response action. If already delivering care and unable to respond, personnel can escalate a new message without even looking at the pager. There are no complex interfaces to distract the provider from their task at hand, no requirement of interaction, and no reason to even think about the pager unless it is delivering a critical message.

Pagers are fast and reliable, and they offer by far the simplest user experience available. Their batteries last for weeks between charges, minimizing any risk of low battery during a shift and greatly simplifying logistical support. They are also small and light enough to clip to a belt or pocket or hang as a pendant. Their simplicity and clarity helps reduce the overall burden on clinical staff and reduce the related level of mistakes and risk.

For critical messaging applications, the advantages easily outweigh the bandwidth limitation, creating a highly reliable and deterministic messaging solution well-suited for mission-critical hospital communications.

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During hurricane Katrina and its aftermath, response paging continued operating properly, despite extensive wind damage, power loss, and flooding that had disabled virtually every other communication system and service in the region.

Independent Panel Reviewing the Impact of Hurricane Katrina on Communications Networks. Report and Recommendations to the Federal Communications Commission, June 12, 2006

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Patient safety depends on effective alarm notification. When used for this purpose, cellular and Wi-Fi reliability and performance lengthen response times and make them unpredictable, and their complexity compounds the issue. In contrast, a response paging system offers fast and reliable alarm handling with a simple and consistent user experience. This ensures patient safety and reduces risk without compromise.

A response paging system is simple, fast, reliable, and cost-effective. It operates on dedicated, FCC-licensed channels, using high power transmitters, self-reliant control equipment, and simple-to-use pagers. Critical messages are delivered quickly to the correct personnel, who get the message at a glance without disruptive user interaction, spotty coverage, or reliance on external equipment. Messages are confirmed, escalated as necessary, and stored for long-term record keeping.

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With unmatched performance and reliability, flawless RF coverage, and a straightforward user experience, response paging is the best solution available for hospital alarm notification.

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Critical Response Systems (Norcross, GA) manufactures mission-critical communication systems, including the SPARKGAP response paging system. SPARKGAP delivers the benefits of response paging to hospitals, with additional enhancements to ensure five 9's availability, 5-second message delivery, HIPAA privacy encryption, and customizable dashboard reporting tools to quickly assess hospital alerting behaviors. For more information regarding response paging and hospital alarm notification, please contact:

Critical Response Systems, Inc.

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1 Florida Department of Transportation. Hurricane Response Evaluation and Recommendations, February 11, 2005, at 39.

2 Independent Panel Reviewing the Impact of Hurricane Katrina on Communications Networks. Report and Recommendations to the Federal Communications Commission, June 12, 2006.

3 Rosenthal B, Kang C, and Williams C. More than 1 million without power, phone service as Hurricane Irene advances, WASH POST, August 2, 2011.

4 Conneally T. Virginia earthquake overloads cell networks from North Carolina to New York, Twitter takes over,, October 2011.

5 Sharp A, Prodhan G. RIM scrambles to end global BlackBerry outage, Reuters, October 12, 2011.

6 Sullivan, P. After Storm, 9-1-1, Phone Service Remains Spotty, WASH. POST, Jul. 2, 2012.

7 Reardon, Marguerite. Hurricane Sandy Disrupts Wireless and Internet Services. CNET News. CBS Interactive, 30 Oct. 2012. Web. 30 Oct. 2012.

8 S Xiaoqiao Meng, Petros Zerfos, Vidyut Samanta, Starsky H. Y. Wong, and Songwu Lu, “Analysis of the Reliability of a Nationwide Short Message Service,” NEC Laboratories America/Deutsche Telekom Laboratories/UCLA Computer Science Department, p. 4,

9 Callisch D. Coping with Wi-Fi's biggest problem: interference. Network World August 2010. 24 October 2012

10 Gill PS, Kamath A, Gill TS. Distraction: an assessment of smartphone usage in health care work settings. Risk Management and Healthcare Policy, August 27, 2012: 105.

11 Westbrook JI, Woods A, Rob MI, Dunsmuir WTM, Day RO. Association of interruptions with an increased risk and severity of medication administration errors. Arch Intern Med.2010;170(8):683-690.

12 Halamka J. Order Interrupted by Text: Multitasking Mishap.

13 Gill PS, Kamath A, Gill TS. Distraction: an assessment of smartphone usage in health care work settings. Risk Management and Healthcare Policy, August 27, 2012: 108.

14 Gill PS, Kamath A, Gill TS. Distraction: an assessment of smartphone usage in health care work settings. Risk Management and Healthcare Policy, August 27, 2012: 111.

15 Arlington County, VA. After-action Report On the Response to the September 11 Terrorist Attack On the Pentagon. Arlington, Va.: The County, 2002, at p A-40.

16 Independent Panel Reviewing the Impact of Hurricane Katrina on Communications Networks. Report and Recommendations to the Federal Communications Commission, June 12, 2006, at p. 24.


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Document 11-094
Version 1.14

Critical Response Systems, Inc.
1670 Oakbrook Drive, Suite 370
Norcross, GA 30093-1849
Tel: 770-441-9559

Copyright © 2011-2013, Critical Response Systems, Inc. All Rights Reserved

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Hospital Patient Safety

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brad dye

With best regards,
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Newsletter Editor

Wireless Messaging News
Brad Dye, Editor
P.O. Box 266
Fairfield, IL 62837 USA


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